Method of semiconductor wafer manufacture, semiconductor wafer for solar plants, and etching solution

FIELD: electrical engineering.

SUBSTANCE: semiconductor wafer intended for application in solar plants, in which uniform and fine structure of irregularities in the form of pyramid is provided evenly within the limits of its surface, and etching solution for generation of semiconductor wafer that has uniform and fine structure of irregularities. Semiconductor is etched with application of alkaline etching solution, which contains at least one type selected from the group that consists of carbonic acids, which have carbon number of 1-12 and have at least one carboxyl group in molecule, and their salts, so that in this manner structure of irregularities is formed on the surface of semiconductor surface.

EFFECT: safe and efficient method for manufacture of semiconductor wafer, which has perfect efficiency of photoelectric conversion, in which fine structure of irregularities suitable for application in solar element may be uniformly shaped with required size on the surface of semiconductor wafer.

12 cl, 16 dwg, 10 tbl

 

The technical field to which the invention relates.

The present invention relates to a method of manufacturing a semiconductor substrate having an uneven structure, which is used for a solar cell, or the like, to a semiconductor substrate for use in solar installations and solution for etching used in this way.

Prior art

Recently, to improve the efficiency of solar cells uses a method that includes forming an uneven structure on the surface of the substrate for efficient transmission of incident light from the surface into the substrate. As a way homogeneous formation of a fine uneven structure on the surface of the substrate in the non-patent document Progress in Photovoltaics: Research and Applications, Vol.4, 435-438 (1996) described a method that includes executing processing, consisting in anisotropic etching using a mixed aqueous solution of sodium hydroxide and isopropyl alcohol for processing the surface of a monocrystalline silicon substrate having a (100) plane on the surface, for forming irregularities in the shape of a pyramid (rectangular pyramids), consisting of (111) plane. However, application of this method due to problems associated with the need for treatment of contaminated waste water, C is the shields of the working environment and safety, in connection with the use of isopropyl alcohol. In addition, the shape and size of the roughness obtained is heterogeneous, so it is difficult to form a uniform thin irregularities located in the plane.

As a solution for etching in the patent document JP 11-233484 As described alkaline aqueous solution containing a surfactant, and in the patent document JP 2002-57139 As described alkaline aqueous solution containing a surfactant, which contains octanoic acid or dolezelova acid as a main component.

Disclosure of the invention

The problem addressed by the invention

The purpose of the present invention is to create a safe and inexpensive method of manufacturing a semiconductor substrate having an excellent photoelectric conversion efficiency, which may uniformly to form a fine uneven structure with a desired size, preferably to a solar cell on the surface of the semiconductor substrate; and a semiconductor substrate for use in solar installations has a uniform and fine uneven structure in the form of pyramids in the plane; and solution for etching, intended for forming a semiconductor substrate having a uniform and fine uneven structure.

For the stijene the above objective, the method of manufacturing a semiconductor substrate in accordance with the present invention differs that includes etching a semiconductor substrate of alkaline etching solution containing at least one type selected from the group consisting of carboxylic acids having a carbon number of 12 or less and having at least one carboxyl group in one molecule, and their salts, in order thus to form an uneven structure on the surface of the semiconductor substrate.

The carboxylic acid preferably represents one of the two or more types selected from the group consisting of acetic acid, propionic acid, butane acid, pentanol acid, hexanoic acid, heptane acid, octanoic acid, nonnovel acid, decanoas acid, undecanoic acid, dodecanol acid, acrylic acid, oxalic acid and citric acid.

In addition, the carbon number of the carboxylic acid is preferably 7 or less. The concentration of carboxylic acid in the etching solution is preferably from 0.05 to 5 mol/L.

By selecting a given one of the two or more types of carboxylic acid as the carboxylic acid in the pickling solution, you can adjust the size of the protrusions on the uneven structure formed on a surface of a semiconductor substrate.

A semiconductor substrate for use in solar have is the sense of in accordance with the present invention has an uneven structure on the surface, obtained using the method in accordance with the present invention.

In addition, it is preferable that the semiconductor substrate for use in solar installations, in accordance with the present invention had a uniform and fine uneven structure in the form of pyramids on the surface of the semiconductor substrate, and to a maximum length dimension of the bottom surface of the uneven patterns ranged from 1 to 20 μm. In the present invention, the maximum side length indicates the average value of the length of one side of the lower surface 10 of the uneven structures sequentially selected in descending order of sizes form an uneven structure on the surface unit 266 mcm ×200 microns.

The semiconductor substrate preferably is a thin substrate of monocrystalline silicon.

The etching solution in accordance with the present invention, is designed for uniform formation of the fine uneven structure in the form of pyramids on the surface of a semiconductor substrate, which is an aqueous solution containing alkali and carboxylic acid carbon number of 12 or less, having at least one carboxyl group in one molecule.

Etching solution preferably who meet the composition, in which the alkali is from 3 to 50 wt.%, carboxylic acid is from 0.05 to 5 mol/l, and the balance of the solution is water.

In addition, the carboxylic acid is preferably a one or two or more types selected from the group consisting of acetic acid, propionic acid, butane acid, pentanol acid, hexanoic acid, heptane acid, octanoic acid, nonnovel acid, decanoas acid, undecanoic acid, dodecanol acid, acrylic acid, oxalic acid and citric acid. The carbon number of the carboxylic acid is preferably 7 or less.

In accordance with the method of manufacturing a semiconductor substrate and etching solution in accordance with the present invention, a semiconductor substrate, which has excellent photoelectric conversion efficiency and has a small homogeneous uneven structure with a desired size, which is preferable for a solar cell can be safely manufactured at low cost. A semiconductor substrate for use in solar installations, in accordance with the present invention, has a uniform and fine structure of irregularities, which is preferred for solar cell and the like, and as a result, using such a semiconductor is if the substrate, can be effectively obtained solar cell having excellent photoelectric conversion.

Brief description of drawings

Figure 1 shows the image results in the form of electron micrographs of example 1, in which part (a) shows the image with magnification of 500, and in part (b) shows the image with magnification of 1000.

Figure 2 shows the image results in the form of electron micrographs in example 2, in which part (a) shows the image with magnification of 500, and in part (b) shows the image with magnification of 1000.

3 shows the image results in the form of electron micrographs in example 3, in which part (a) shows the image with magnification of 500, and in part (b) shows the image with magnification of 1000.

4 shows the image results in the form of electron micrographs in example 4, in which part (a) shows the image with magnification of 500, and in part (b) shows the image with magnification of 1000.

Figure 5 presents the image results in the form of electron micrographs for comparative example 1, in which part (a) shows the image with magnification of 500, and in part (b) shows the image with magnification of 1000.

Figure 6 presents the image results in the form of electron micrographs in example 5, in which part (a) shows the image is agenia with increasing 500, in part (b) shows the image with magnification of 1000.

Figure 7 presents the image results in the form of electron micrographs in example 6, in which part (a) presents the image with a magnification of 500, and in part (b) presents the image with a magnification of 1000.

On Fig shows the image results in the form of electron micrographs in example 7, in which part (a) presents the image with a magnification of 500, and in part (b) presents the image with a magnification of 1000.

Figure 9 shows an example image, which was obtained excellent standard evaluation on the surface of the substrate after the etching processing according to example 8.

Figure 10 shows an example image, which was obtained a satisfactory standard of valuation on the surface of the substrate after the etching processing according to example 8.

Figure 11 shows the example image, which was obtained acceptable standard on the substrate surface after processing by etching in example 8.

On Fig presents an image of the sample that was obtained unsuccessful valuation standard on the substrate surface after processing by etching in example 8.

On Fig presents the image results in the form of electron micrographs in example 15.

On Fig presents the image results in the form of electron micrographs in example 16.

On Fig presents the image results in the form of electron micrographs in example 17.

On Fig presents the image results in the form of electron micrographs in example 18.

Detailed description of the invention

In accordance with the method of manufacturing a semiconductor substrate, in accordance with the present invention, an alkaline solution containing at least one type selected from the group consisting of carboxylic acids having a carbon number of 12 or less and having at least one carboxyl group in one molecule, and their salts, is used as an etching solution, and the semiconductor substrate is soaked in an etching solution to perform on the surface of the substrate anisotropic etching, resulting in the surface of the substrate is formed of a homogeneous and fine uneven structure.

As the above carboxylic acids can be widely used well-known organic compounds, each of which has a carbon number of 12 or less and has at least one carboxyl group in one molecule. Although the number of carboxyl groups, in particular, not focused, preferably it is from 1 to 3. That is, it is preferable to use monocarboxylic acids, dicarboxylic acids and tricarboxylic acids. Carbon Chi is lo carboxylic acid is 1 or more, preferably 2 or more and more preferably 4 or more and 12 or less, preferably 10 or less and more preferably 7 or less. As the above carboxylic acids, although there may be any carboxylic acids with chain molecular structure and cyclic carboxylic acids, preferably carboxylic acids with chain molecular structure, in particular it is preferable to use carboxylic acids with chain structure of molecules with carbon number from 2 to 7.

Examples of carboxylic acids with chain molecular structure include: monocarboxylic chain saturated acids (saturated fatty acids), such as formic acid, acetic acid, propanoic acid, butane acid, pentane acid, hexanoic acid, hechanova acid, octanoic acid, novanova acid, cekanova acid, undecanoate acid, dodekanisa acid and their isomers; saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, Emelyanova acid and their isomers; saturated aliphatic tricarboxylic acids such as propanetricarboxylate acid and MELANTRICHOVA acid; unsaturated fatty acids such as acrylic acid, butenova acid, pontenova to the slot, hexenoic acid, geptanona acid, pentadienoic acid, hexadienoic acid, heptadiene acid and atsetilendikarbonovoi acid; aliphatic unsaturated dicarboxylic acids such as potentionaly acid, intentionaly acid, hexandione acid, hexandione acid and acetylenedicarbonic acid; and unsaturated aliphatic tricarboxylic acids such as konitova acid.

Examples of cyclic carboxylic acids include: alicyclic carboxylic acids, such as cyclopropanecarbonyl acid, cyclobutanecarbonyl acid, cyclopentanecarbonyl acid, cyclohexanecarbonyl acid, cyclopropanecarbonyl acid, cyclobutanecarbonyl acid, cyclopentanecarbonyl acid, cyclopropanecarbonyl acid and cyclobutanecarbonyl acid; and aromatic carboxylic acids such as benzoic acid, phthalic acid and benzotriazole acid.

In addition, it is also possible to use organic compounds containing a carboxyl group, each of which has a different functional group other than the carboxyl group. Examples include hydroxycarboxylic acids such as glycolic acid, lactic acid, hydrography acid, oxibutinina acid, glyceric acid, castronova acid, malic acid, tartaric acid, citric acid, salicylic acid and gluconic acid; metacarbonate acids such as pyruvic acid, acetoacetic acid, propionyloxy acid and levonova acid; and alkoxycarbonyl acid, such as methoxycarbonyl acid and toxicsuse acid.

Preferred examples of such carboxylic acids include acetic acid, propionic acid, butane acid, pentane acid, hexanoic acid, heptane acid, octanoic acid, nonanoyl acid, dekanovu acid, undecanoyl acid, dodekanisou acid, acrylic acid, oxalic acid and citric acid.

As the carboxylic acid in the etching solution, it is preferable to use a carboxylic acid containing at least one carboxylic acid having a carbon number of 4-7, as a main component, and if required, it is preferable to add a carboxylic acid having a carbon number of 3 or less, or carboxylic acid having a carbon number of 8 or more.

The concentration of carboxylic acid in the etching solution is preferably from 0.05 to 5 mol/l, more preferably from 0.2 to 2 mol/L.

In the production process, in accordance with the present invention, in the selection of the specified carboxylic acids can is about to resize the form uneven patterns on the surface of the semiconductor substrate. In particular, through the use of etching solution composed of a mixture of a variety of carboxylic acids having different carbon numbers, you can adjust the amount of protrusion in the shape of a pyramid uneven patterns on the surface of the substrate. When the carbon number of the added carboxylic acid is small, the size of the unequal patterns becomes smaller. For the homogeneous formation of small bumps is preferable to add the carboxylic acid contains one or two or more types of aliphatic carboxylic acids with a carbon number of 4-7, as main components, and if required, other carboxylic acids.

As the above alkaline solution used is an aqueous solution in which the dissolved alkali. As the alkali can be any organic alkali and inorganic alkali. As organic bases, for example, it is preferable to use Quaternary ammonium salt, such as a hydroxide of tetraethylammonium and ammonia. As the inorganic alkali is preferable to use a hydroxide of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide and calcium hydroxide, with sodium hydroxide or potassium hydroxide are particularly preferred. Such alkali can use the CTD is Ino or in combination of, at least two types. The concentration of alkali in the etching solution is preferably 3-50 wt.%, more preferably 5-20 wt.% and even more preferably 8-15 wt.%.

As mentioned above a semiconductor substrate, although it is preferable to use a substrate of monocrystalline silicon, it is also possible to use a single crystal semiconductor substrate, which uses a semiconductor compound such as germanium and gallium arsenide.

In the method, in accordance with the present invention, the etching process is not limited specifically. The semiconductor substrate is soaked or the like within a predetermined period of time, using the etching solution, heated to maintain the desired temperature, resulting in the surface of the semiconductor substrate is formed of a homogeneous and fine uneven structure. Although the temperature of the etching solution is not limited specifically, it is preferable to use the range from 70 to 98°C. Although the time of etching is not limited specifically, it is preferable to use from 15 to 30 minutes.

In accordance with the method of manufacturing a semiconductor substrate in accordance with the present invention receive a semiconductor substrate with a homogeneous unequal structure in the shape of a pyramid, in which the maximum is the length of the bottom surface is equal to from 1 to 20 μm, the upper limit of its value is preferably 10 μm, more preferably 5 μm, and the angle of the vertex in the vertical section is 110°. In addition, in accordance with the present invention, can be obtained with low cost semiconductor substrate with a low reflectivity.

Information confirming the possibility of carrying out the invention

Examples

Below the present invention will be described more specifically by examples. However, it should be understood that these examples are presented for illustrative purposes and should not be interpreted as limiting.

Example 1

Using the etching solution in which 30 g/l (approximately 0.26 mol/l) hexanoic acid was added to 12.5 wt.% an aqueous solution of KOH as an etching solution, soaked a substrate of single crystal silicon having a (100) plane surface at 90°within 30 minutes. After that, the surface of the processed substrate was observed using e-microsemi. Figure 1 shows the results obtained in the form of electron micrographs. Figure 1(a) presents the case of increase of 500, and figure 1(b) presents the case of increase of 1000. In addition, the uneven structure on the unit square with dimensions of 265 μm to 200 μm chose 10 uneven structures sequentially in descending order of the size of the form is, and he measured the length of a side on the bottom surface of each of the pyramidal structures. The result was the average length of a side, that is, the maximum length of the bottom surface was 9.1 μm. Table 1 presents the results of examples 1-4 and comparative example 1.

Example 2

The experiment was performed in the same manner as in example 1, except that the used etching solution, in which instead of hexanoic acid used 30 g/l (approximately 0.23 mol/l) heptane acid. Figure 2 shows the results obtained in the form of electron micrographs. In addition, the maximum length of the bottom surface of the uneven structure was 11.0 μm.

Example 3

The experiment was conducted in the same manner as in example 1, except that the used etching solution, in which instead of hexanoic acid used 30 g/l (approximately 0.21 mol/l) octanoic acid. Figure 3 shows the results obtained in the form of electron micrographs. In addition, the maximum length of the bottom surface of the uneven structure amounted to 21.1 μm.

Example 4

The experiment was conducted in the same manner as in example 1, except that the used etching solution, in which instead of hexanoic acid were added to 30 g/l (about 0,19 mol/l) nonanalog is islote. Figure 4 shows the results obtained in the form of electron micrographs. In addition, the maximum length of the bottom surface of the uneven structure was 32,1 microns.

Comparative example 1

The experiment was performed in the same manner as in example 1 except that the used etching solution, in which instead of hexanoic acid was added isopropyl alcohol (IPA, IPS) so that the solution contained 10 wt.%. The IPS. Figure 5 shows the results obtained in the form of electron micrographs. In addition, the maximum length of the bottom surface of the uneven structure amounted to $ 24.8 microns.

Table 1
The composition of the etching solutionThe roughness of the substrate
Carboxylic acidThe concentration of CONThe maximum length of a side on the bottom surfaceUniformity
Example 1Hexanoic acid12,5%9,1 mcmUniform
Example 2Heptane acid12,5%of 11.0 μmUniform
Example 3Octanoic acid125% 21,1 mcmUniform
Example 4Novanova acid12,5%32,1 mcmUniform
Comparative Example 1IPS12,5%24,8 mcmHeterogeneous

As shown in figure 1-4 and in table 1, in examples 1-4, in which the used etching solution in accordance with the present invention, was formed structure irregularities having a uniform and small protrusions in the form of pyramids, evenly spaced over the entire surface of the substrate. In addition, the size of the protrusions in the shape of pyramids is changed in accordance with the carbon number of the aliphatic carboxylic acid contained in the solution. In addition, the measurement result of the degree of reflection at the wavelength of 800 nm substrates obtained in examples 1-4, received on average reflectivity of 7-8%. Thus, there were obtained extremely good results.

On the other hand, as shown in figure 5 and in table 1, as for the etching solution, which was added isopropanol, there was obtained the uneven size of the protrusions in the shape of pyramids, and watched a certain number superimposed on each pyramidal forms.

Example 5

Using the etching solution, in which the aqueous solution of 12.5 wt%. KOHN was added heptane acid and nonnovel acid as the etching solution, an experiment was conducted in the same manner as in example 1. The number of added hexanoic acid and nonnovel acid was 60 g/l and 30 g/l, respectively. Figure 6 presents the results obtained in the form of electron micrographs. Table 2 shows the results for examples 5-7.

Example 6

An experiment was conducted in the same manner as in example 5, except that the amount added heptane acid and nonnovel acid was changed to 30 g/l, respectively. 7 shows the results obtained in the form of electron micrographs.

Example 7

An experiment was conducted in the same manner as in example 5, except that the amount added heptane acid and nonnovel acid was changed to 30 g/l and 60 g/l, respectively. On Fig shows the results obtained in the form of electron micrographs.

Uniformity
Table 2
The composition of the etching solutionThe roughness of the substrate
Carboxylic acid [Proportion by mass]The concentration of CONThe maximum length of a side on the bottom surface
Example 5Heptane acid+novanova acid [2:1]12,5%of 11.5 micronsUniform
Example 6Heptane acid+novanova acid [1:1]12,5%15,0 µmUniform
Example 7Heptane acid+novanova acid [1:2]12,5%21,1 mcmUniform

As shown in Fig.6-8 and in table 2, through the use of etching solution with lots of aliphatic carboxylic acids, with an admixture, it is possible to easily adjust the size of the protrusions in the shape of a pyramid structure irregularities on the substrate surface.

Example 8

First, as shown in table 3, were prepared etching solution containing an alkali and an aliphatic carboxylic acid, using water as the balance. Using 6 l pickling solution at a liquid temperature of from 80 to 85°, dunk a substrate of monocrystalline silicon having a (100) plane on the surface for 30 minutes, and then the surface of the processed substrate was visually observed.

Table 3 presents the results of visual observations. In table 3 substrate with a pyramid-shaped small heterogeneous structures, the create is on the surface, evaluated by classifying into three stages (uniformity: excellent>satisfactory>acceptable) to assess the heterogeneity of irregularities. Substrate without the fine uneven structures of a pyramidal shape formed on the surface was determined as a failure. On Fig.9-12 shows pictures representing examples of surfaces of substrates with an excellent, satisfactory, acceptable and bad evaluation.

Table 3
Example 8
Carboxylic acid

Lye
Hexanoic acid (mol/l)
0,430,360,290,220,140,070,06
CON 6 wt.%ExcellentExcellentSatisfactoryAcceptableFailedFailedFailed
The STAKE of 12.5 wt.%AcceptableExcellentExcellentSatisfactoryAcceptableFailedFailed
CON 25 wt.%AcceptableSatisfactorySatisfy your high is satisfactory AcceptableAcceptableAcceptableFailed
CON 50 wt.%FailedAcceptableSatisfactorySatisfactoryAcceptableAcceptableAcceptable

Example 9

The experiment was conducted in the same manner as in example 8, except that the etching solution used etching solution having the composition shown in table 4. The results are shown in table 4.

Table 4
Example 9
Carboxylic acid

Lye
Heptane acid (mol/l)
0,380,320,260,190,13
CON 6 wt.%FailedFailedAcceptableAcceptableSatisfactory
The STAKE of 12.5 wt.%SatisfactoryExcellentExcellentSatisfactoryFailed
CON 25 wt.%SatisfactoryExcellent/td> ExcellentSatisfactorySatisfactory
CON 50 wt.%ExcellentExcellentSatisfactorySatisfactorySatisfactory

Example 10

The experiment was conducted as in example 8, except that the etching solution used solution having the composition shown in table 5. The results are presented in table 5.

td align="center"> Failed
Table 5
Example 10
Carboxylic acid

Lye
Octanoic acid (mol/l)
0,350,290,230,170,120,060,050,03
CON 6 wt.%ExcellentSatisfactorySatisfactoryFailedFailed.FailedFailedFailed
The STAKE of 12.5 wt.%ExcellentExcellentSatisfactorySatisfactoryAcceptableAcceptableFailed
CON 25 wt.%ExcellentExcellentSatisfactorySatisfactoryAcceptableAcceptableAcceptableFailed
CON 50 wt.%ExcellentExcellentSatisfactorySatisfactoryAcceptableAcceptableAcceptableAcceptable

Example 11

The experiment was conducted in the same manner as in example 8, except that the etching solution used etching solution having the composition shown in table 6. The results are shown in table 6.

Failed
Table 6
Example 11
Carboxylic acid

Lye
Novanova acid (mol/l)
0,320,260,210,160,110,050,04
CON 6 wt.%AcceptableAcceptableFailedFailedFailedFailed
The STAKE of 12.5 wt.%ExcellentExcellentExcellentFailedFailedFailedFailed
CON 25 wt.%ExcellentExcellentExcellentSatisfactorySatisfactoryFailedFailed
CON 50 wt.%ExcellentExcellentExcellentExcellentSatisfactorySatisfactorySatisfactory

Example 12

The experiment was conducted in the same manner as in example 8, except that the etching solution used etching solution having the composition shown in table 7. The results are shown in table 7.

Table 7
Example 12
Carboxylic acid

Lye
Cekanova acid (mol/l)
0,290,240,190,150,100,050,04
CON 6 wt.%Failed FailedAcceptableAcceptableFailedFailedFailed
The STAKE of 12.5 wt.%AcceptableAcceptableAcceptableAcceptableAcceptableAcceptableAcceptable
CON 25 wt.%AcceptableSatisfactorySatisfactoryAcceptableAcceptableAcceptableAcceptable
CON 50 wt.%AcceptableSatisfactoryExcellentSatisfactorySatisfactoryAcceptableAcceptable

Example 13

The experiment was conducted in the same manner as in example 8, except that the etching solution used etching solution having the composition shown in table 8. The results are shown in table 8.

0,05
Table 8
Example 13
Carboxylic acid

Lye
Undecanoate acid (mol/l)
0,090,04
CON 25 wt.%FailedAcceptableAcceptable
CON 50 wt.%AcceptableAcceptableAcceptable

Example 14

The experiment was conducted in the same manner as in example 8, except that the etching solution used etching solution having the composition shown in table 9. The results are presented in table 9.

Table 9
Example 14
Carboxylic acid

Lye
Dodekanisa acid (mol/l)
0,080,040,03
CON 25 wt.%FailedAcceptableAcceptable
CON 50 wt.%AcceptableAcceptableAcceptable

Example 15

Using 6 l of an aqueous KOH solution (6 wt%), containing 200 g (approximately 0.55 mol/l) acetic acid as an etching solution, a substrate of monocrystalline silicon (weight: 7.68 in) thickness: 222 μm)having the (100) plane on the surface, soaked at a temperature of from 90 to 95°within 30 m of the nut, in the result, there was obtained a substrate (weight: 5,47 g, thickness: 171 μm)having fine irregularities on the surface. The surface-treated substrate was observed using e-microsemi. On Fig presents the results obtained with the help of electron micrographs (magnification: 1000, 3 phases). The maximum length of the bottom surface of the uneven structure on the surface of the obtained substrate was 15,0 µm. Table 10 shows the results of examples 15-18.

Example 16

Using 6 l of an aqueous KOH solution (6 wt%), containing 200 g (about 0,17 mol/l) citric acid as an etching solution, a substrate of monocrystalline silicon (weight: 7,80 g, thickness: 227 μm)having plane (100) surface, soaked at a temperature of from 90 to 95°C for 20 minutes, the result was obtained substrate (weight: 6,44 g, width: 193 μm)having fine irregularities on the surface. On Fig shows the results obtained with the help of electron micrographs (magnification: 1000, 3 phases). The maximum length of the bottom surface of the uneven structure on the surface of the obtained substrate was 10.0 μm.

Example 17

Using 6 l of an aqueous KOH solution (6 wt%), containing 300 grams (approximately 0.69 mol/l) acrylic acid as the etching solution, a substrate of monocrystalline what about the silicon (SLOT 5, weight: 9,66 g, width: 279 microns and SLOT 20, weight: 9,66 g, thickness: 283 μm), each of which had a (100) plane on the surface, soaked at a temperature of from 90 to 95°C for 30 minutes, resulting in the obtained substrate (SLOT 5, weight: 7,56 g, thickness: 239 μm and SLOT 20, weight: 7,53 g, thickness: 232 μm), each having small unevenness on the surface. On Fig shows the results obtained with the help of electron micrographs (magnification: 1000). The maximum length of a side of the lower surfaces of the uneven structures on the surface of the obtained substrate was 17.0 μm.

Example 18

Using 6 l of an aqueous KOH solution (6 wt%), containing 200 g (about 0,37 mol/l) of oxalic acid as an etching solution, a substrate of monocrystalline silicon (SLOT 5, weight: 9.60 g, thickness: 289 μm, and SLOT 20, weight: 9,65 g, width: 285 μm), each having a (100) plane on the surface, soaked at a temperature of from 90 to 95°C for 30 minutes, resulting in the obtained substrate (SLOT 5, weight: 7,60 g, thickness: 239 μm and SLOT 20, weight: 7,60 g, width: 244 μm), each of which had minor irregularities on the surface. On Fig shows the results obtained with the help of electron micrographs (magnification: 1000, 3 phases). The maximum length of a side of the lower surfaces of the uneven structures on the surface of the obtained substrate was 15,0 ám.

Table 10
The composition of the etching solutionThe heterogeneity of the substrate
Carboxylic acidThe concentration of CONThe maximum length of the sides on the bottom surfaceUniformity
Example 15Acetic acid6%15,0 µmUniform
Example 16Citric acid6%10,0 µmUniform
Example 17Acrylic acid6%17,0 mcmUniform
Example 18Oxalic acid6%15,0 µmUniform

1. Method of manufacturing a semiconductor substrate, which consists in etching a semiconductor substrate of alkaline etching solution containing at least one type of carboxylic acid having a carbon number of 1-12, and having at least one carboxyl group in one molecule, and their salts for the formation of irregularities on the surface of the semiconductor substrate.

2. The method according to claim 1, characterized in that the carboxylic acid is a on the in, or two or more types selected from the group consisting of acetic acid, propionic acid, butane acid, pentanol acid, hexanoic acid, heptane acid, octanoic acid, nonnovel acid, decanoas acid, undecanoic acid, dodecanol acid, acrylic acid, oxalic acid and citric acid.

3. The method according to claim 1, characterized in that the carboxylic acid has a carbon number of 7 or less.

4. The method according to claim 1, wherein the etching solution contains carboxylic acid in a concentration of from 0.05 to 5 mol/L.

5. The method according to claim 1, characterized in that it further carry out the selection of a given one, or two or more types of carboxylic acid as the carboxylic acid used in the pickling solution to regulate the sizes of the protrusions in the shape of a pyramid structure irregularities formed on the surface of the semiconductor substrate.

6. The semiconductor substrate used in solar installations containing structure irregularities on its surface, obtained by the method according to claims 1-5.

7. The semiconductor substrate according to claim 6, further containing a homogeneous and fine structure of the irregularities in the shape of a pyramid on its surface, in which the structure of the bump has a bottom surface having a maximum length of side 1 to 20 MK is.

8. The semiconductor substrate according to claim 6 or 7, which is a thin substrate of monocrystalline silicon.

9. Etching solution for uniform formation of a fine structure irregularities in the shape of a pyramid on the surface of a semiconductor substrate, which is an aqueous solution containing alkali and carboxylic acid having a carbon number of 12 or less and at least one carboxyl group in one molecule.

10. The etching solution according to claim 9, which contains at to 50 wt.% alkali, from 0.05 to 5 mol/l carboxylic acid and the rest is water.

11. The etching solution according to claim 9 or 10, in which the carboxylic acid is one or two or more types of acid selected from the group consisting of acetic acid, propionic acid, butane acid, pentanol acid, hexanoic acid, heptane acid, octanoic acid, nonnovel acid, decanoas acid, undecanoic acid, dodecanol acid, acrylic acid, oxalic acid and citric acid.

12. The etching solution according to claim 9, in which the carboxylic acid has a carbon number of 7 or less.



 

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27 cl, 21 dwg

FIELD: technological processes.

SUBSTANCE: invention concerns selective membrane production for molecular gas mix filtering and can be applied in compact fuel cells. Method of gas-permeable membrane production includes vacuum sputtering of a metal displaying chemical stability in concentrated hydrogen fluoride solutions in anode polarisation conditions onto monocrystalline silicon plate in closed pattern, and further double-side electrochemical etching of the plate area limited by the mentioned closed pattern. Etching process is performed until its spontaneous cease determined by break of time function curve of anode current on the plate surface not covered by sputtered metal.

EFFECT: increased thickness homogeneity of solid monocrystalline filtering silicon layer, improved membrane durability at higher gas permeability.

31 cl, 9 dwg, 2 ex

FIELD: physics.

SUBSTANCE: invention is related to the field of manufacture of micromechanical devices, namely to methods of formation of scanning probe microscope probes, in particular, cantilevers consisting of console and needle. In method of cantilever manufacture that includes formation of KDB on top surface of single-crystal silicic wafer with orientation (100) of cantilever needle by method of local anisotropic etching of silicon, formation of p-n transition on top side of wafer, local electrochemical etching of wafer from the back side to p-n transition with creation of silicic membrane, formation of cantilever console from the saidmembrane by means of local anisotropic etching of membrane from both sides of plate with application of mask that protects needle and top part of console, needle of cantilever is formed prior to formation of p-n transition. Depth of n-layer amounts to doubled thickness of console, and mask for local anisotropic etching of membrane is received by method of lift-off lithography with application of bottom "sacrificial" layer and top masking layer from chemically low-activity metal.

EFFECT: obtaining of cantilever with reproduced geometric parameters of console and higher resolution of needle.

3 cl, 15 dwg

FIELD: physics; electricity.

SUBSTANCE: etching system contains plasma-generating facilities for plasma generating in vacuum chamber, high-frequency displacement voltage source, supplying high-frequency displacement voltage to electrode-substrate, floating electrode opposite to electrode-substrate in vacuum chamber and supported in floating condition by electric potential, solid material placed on the side of the floating electrode directed to electrode-substrate to form film layer protecting from etching, and control unit for periodic supply of high-frequency voltage to floating electrode. Etching method includes repetition, in specified sequence, of substrate etching stage by means of etching gas supplied to vacuum chamber, and film layer formation stage protecting substrate from etching by sputtering of solid material opposite to substrate.

EFFECT: high etching selectivity when using mask as well as production of anisotropic profile and great etching depth.

22 cl, 7 dwg

FIELD: chemistry.

SUBSTANCE: invention pertains to compositions used for treating surfaces and the method of treating the surface of a substrate, using such a composition. The essence of the invention is that, the cleaning solution contains water, hydrogen peroxide, an alkaline compound and 2,2-bis-(hydroxyethyl)-(iminotris)-(hydroxymethyl)methane as a chelating additive. The alkaline compound is preferably chosen from a group containing an organic base, ammonia, ammonium hydroxide, tetramethylammonium hydroxide, and most preferably from a group containing ammonia and ammonium hydroxide. Content of the chelating additive is 1000-3000 ppm. The cleaning solutions are used for the process of treating the surface, including cleaning, etching, polishing, and film-formation, for cleaning substrates, made from semiconductor, metal, glass, ceramic, plastic, magnetic material, and superconductors. The method involves treatment of semiconductor substrate(s) using a cleaning solution and drying the given semiconductor substrate(s) after washing in water.

EFFECT: increased stability of the solution at high temperature and increased degree of purification of surfaces.

3 cl, 2 tbl, 15 dwg, 3 ex

FIELD: methods for manufacture of semi-conductor instruments and microcircuit chips.

SUBSTANCE: method and system are suggested for treatment of base plates for treatment of semi-conductor instruments with creation of liquid meniscus that is shifted from the first surface to the parallel second one, which is installed nearby. System and method suggested in invention may also be used for meniscus shift along base plate edge.

EFFECT: invention provides efficient cleaning and drying of surfaces and edges of semi-conductor plates, with simultaneous reduction of quantity of water or washing liquid drops that are accumulated on plate surface, which leave dirty traces on plate surface and edge after evaporation.

20 cl, 20 dwg

FIELD: electric engineering.

SUBSTANCE: invention relates to electric engineering equipment and may be used for application of coatings by electrochemical process. The device for one-side treatment of semiconductor plates comprises a galvanic bath with anode and a substrate holder with a set of electrode conducting contacts and support posts whereto a semiconductor plate is pressed. The device incorporates additionally a horizontal support frame with an angular flange and three needle-type stops with ring-like marks, the substrate holder being provided with a guiding angular recess and mounted on the support frame flange. Also, the device comprises the current source control unit and a system of forced mixing of electrolyte made up of a magnetic mixer with a shielding plate.

EFFECT: increased quality of galvanic treatment of semiconductor plates, simpler design of the device.

5 dwg

FIELD: semiconductor engineering; chemical treatment of single-crystalline silicon wafer surfaces chemically resistant to open air and suited to growing epitaxial semiconductor films.

SUBSTANCE: proposed method for treatment of single-crystalline silicon wafer surface positioned on Si(100) or Si(111) plane includes cleaning of mentioned surface followed by passivation with hydrogen atoms. Silicon surface is first cleaned twice by means of boiling trichloroethylene solution for 10-20 minutes involving washing with deionized water and then with ammonium-peroxide aqueous solution of following composition: 5 volumes of H2O, 1 volume of 30% H2O2, 1 volume of 25% NH4OH at 75-82 °C or with salt-peroxide aqueous solution of following composition: 6 volumes of H2O, 1 volume of 30% H2O2, 1 volume of 37% HCl at 75-82 °C, followed by three 5- or 10-minute steps of washing with deionized water; passivation with hydrogen atoms is conducted by treatment first with 5-10 mass percent HF solution and then with aqueous solution of NH4OH and NH4F mixture at pH = 7.6-7.7 for 40-60 s followed by washing with deionized water and drying out under normal conditions.

EFFECT: ability of producing wafers capable of retaining their serviceability for long time in storage and in transit, in open air, without oxidizing their surfaces.

1 cl, 3 dwg

FIELD: semiconductor device manufacture; pre-heat cleaning of silicon substrate surfaces from organic and mechanical contaminants.

SUBSTANCE: proposed method for cleaning silicon substrates includes their double-stage treatment in two baths filled with two solutions: first bath is filled with solution of sulfuric acid H2SO4 and hydrogen peroxide H2O2 in H2SO4 : H2O2 = 10 : 1 proportion at temperature T = 125 °C; other bath is filled with solution of aqueous ammonia NH4OH, hydrogen peroxide H2O2, and deionized water H2O in proportion of NH4OH : H2O2, : H2O at temperature T = 65 °C. Resulting amount of dust particles is not over three.

EFFECT: ability of removing all organic and mechanical contaminants and impurities from silicon substrate surface, reduced substrate treatment time.

1 cl

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluorocyclobutane. Method is carried out by interaction of crude octafluorocyclobutane containing impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that is able to eliminate indicated impurities up to the content less 0.0001 wt.-% from the mentioned crude octafluorocyclobutane. Impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurity represents at least one fluorocarbon taken among the group consisting of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,2,2,2-tetrafluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, hexafluoropropene and 1H-heptafluoropropane. Adsorbent represents at least one of representatives taken among the group including activated carbon, carbon molecular sieves and activated coal. Crude octafluorocyclobutane interacts with the mentioned impurity-decomposing agent at temperature from 250oC to 380oC. Invention proposes gas, etching gas and purifying gas including octafluorocyclobutane with purity degree 99.9999 wt.-% and above and comprising fluorocarbon impurity in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluorocyclobutane.

EFFECT: improved purifying method.

26 cl, 13 tbl, 10 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluoropropane. Method is carried out by interaction of crude octafluoropropane comprising impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that are able to remove indicated impurities up to the content less 0.0001 wt.-% from indicated crude octafluoropropane. The impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurities represent at least one compound taken among the group consisting of chloropentafluoroethane, hexafluoropropene, chlorotrifluoromethane, dichlorodifluoromethane and chlorodifluoromethane. Adsorbent represents at least one substance taken among the group consisting of activated coal, molecular sieves and carbon molecular sieves. Crude octafluoropropane comprises indicated impurities in the amount from 10 to 10 000 mole fr. by mass. Invention proposes gas, etching gas and purifying gas comprising octafluoropropane with purity degree 99.9999 wt.-% and above and containing chlorine compound in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluoropropane.

EFFECT: improved purifying method.

13 cl, 11 tbl, 12 ex

FIELD: polymer materials.

SUBSTANCE: method of applying high-resolution image of functional layers, e.g. for applying lithographic mask or other functional layers, comprises polymerization of monomers from vapor phase under action of finely focused electron beam with energy 1 to 1000 keV followed by injection of monomer vapors at pressure from 10-4 to 10 torr. Electron beam is introduced into working chamber through a small opening in membrane, which enables avoiding scattering of electrons on membrane and, at the same time, maintaining monomer vapor pressure in working chamber high enough to ensure acceptable growth time for thickness (height) of image line. Preferred image applying conditions are the following: electron energy in electron beam 10 to 500 keV and monomer vapor pressure 0.001 to 10 torr. For electron beam diameter 50 nm, image width 100-150 nm can be obtained. When improving electron beam focusing, accessible electron beam diameter may be further diminished.

EFFECT: enabled high-resolution image of functional layers directly from monomer in single-step "dry" process without using any solvents.

2 cl, 2 dwg, 8 ex

FIELD: semiconductor microelectronics; high-degree surface cleaning technologies.

SUBSTANCE: proposed method can be used in resource and energy conservation environmentally friendly and safe technology for integrated circuit manufacture, removal of positive photoresist from wafer surface, electrochemical etching of silicon, and degreasing of surfaces. Si surface is cleaned by detergent NH4HF2 of 0.1 - 4 M concentration activated by ozone at anode current density of 1 - 2 kA/m2, and waste solution is cleaned and activated by sequentially passing it through electrolyzer cathode and anode chamber.

EFFECT: enhanced quality and effectiveness of photoresist removal from semiconductor surface.

2 cl, 2 dwg

FIELD: plasma-chemical treatment of wafers and integrated circuit manufacture.

SUBSTANCE: proposed device that can be used in photolithography for photoresist removal and radical etching of various semiconductor layers in integrated circuit manufacturing processes has activation chamber made in the form of insulating pipe with working gas admission branch; inductor made in the form of inductance coil wound on part of pipe outer surface length and connected to high-frequency generator; reaction chamber with gas evacuating pipe, shielding screens disposed at pipe base, and temperature-stabilized substrate holder mounted in chamber base. In addition device is provided with grounded shield made in the form of conducting nonmagnetic cylinder that has at least one notch along its generating line and is installed between inductor and pipe; shielding screens of device are made in the form of set of thin metal plates arranged in parallel at desired angle to substrate holder within cylindrical holder whose inner diameter is greater than maximal diameter of wafers being treated. Tilting angle, quantity, and parameters of wafers are chosen considering the transparency of gas flow screen and ability of each wafer to overlap another one maximum half its area. In addition substrate holder is spaced maximum four and minimum 0.6 of pipe inner diameter from last turn of inductance coil; coil turn number is chosen to ensure excitation of intensive discharge in vicinity of inductor depending on generator output voltage and on inner diameter of pipe using the following equation:

where n is inductance coil turn number; U is generator output voltage, V; Dp is inner diameter of pipe, mm.

EFFECT: enhanced speed and quality of wafer treatment; reduced cost due to reduced gas and power requirement for wafer treatment.

1 cl, 6 dwg, 1 tbl

FIELD: microelectronics.

SUBSTANCE: proposed method that can be used for photolytic etching of wafers in the course of manufacture of very large-scale integrated circuit includes etching of SiO2 surface in sulfur hexafluoride under action of vacuum ultraviolet emission of deuterium-vapor lamp. Argon is introduced in addition into etching gas.

EFFECT: enhanced selectivity of silicon dioxide etching with respect to monocrystalline and polycrystalline silicon.

3 cl, 1 tbl

FIELD: process equipment for manufacturing semiconductor devices.

SUBSTANCE: plasma treatment chamber 200 affording improvement in procedures of pressure control above semiconductor wafer 206 is, essentially, vacuum chamber 212, 214, 216 communicating with plasma exciting and holding device. Part of this device is etching-gas source 250 and outlet channel 260. Boundaries of area above semiconductor wafer are controlled by limiting ring. Pressure above semiconductor wafer depends on pressure drop within limiting ring. The latter is part of above-the-wafer pressure controller that provides for controlling more than 100% of pressure control area above semiconductor wafer. Such pressure controller can be made in the form of three adjustable limiting rings 230, 232, 234 and limiting unit 236 on holder 240 that can be used to control pressure above semiconductor wafer.

EFFECT: enhanced reliability of pressure control procedure.

15 cl, 13 dwg

FIELD: manufacture of microelectronic and nanoelectronic devices.

SUBSTANCE: selective etchant of AlAs and AlGaAs layers relative to GaAs has iodine I2 and organic solvent wherein iodine I2 is dissolved, proportion of mentioned components being as follows, mass percent: iodine, 0.1 - 4; organic solvent, 96 - 99.9. Isopropyl alcohol or acetone can be used as organic solvent. Enhanced selectivity of etching AlAs and AlGaAs layers including those with low Al content (below 40%), as well as their high selectivity relative to InAs and InGaAs are attained at room temperature.

EFFECT: ability of using proposed etchant in nanotechnology for separating upper layers in the order of several single layers.

2 cl

FIELD: engineering of semiconductor devices.

SUBSTANCE: invention concerns method and device for etching dielectric, removing etching mask and cleaning etching chamber. In etching chamber 40 semiconductor plate 56 is positioned. Dielectric 58 made on semiconductor plate is subjected to etching, using local plasma, produced by special device for producing local plasma during etching process. Mask for etching 60 is removed by means of plasma from autonomous source 54, generated in device for producing plasma from autonomous source connected to etching chamber. Etching chamber after removal of semiconductor plate is subjected to cleaning, using either local plasma, or plasma from autonomous source. To achieve higher level of cleaning, it is possible to utilize a heater, providing heating for chamber wall.

EFFECT: increased efficiency.

2 cl, 4 dwg

FIELD: technology for producing semi-penetrable membranes for molecular filtration of gas flows and for division of reaction spaces in chemical reactors.

SUBSTANCE: method for producing gas-penetrable membrane includes two-sided electro-chemical etching of monocrystalline plate made of composition AIIIBV of n conductivity type or of semiconductor AIV with width of forbidden zone E≥1,0 electron volts and alloying level 1017-1020 1/cm3. Modes of aforementioned etching are set, providing for generation of simultaneously porous layers, while etching process is performed until moment of spontaneous stopping of electro-chemical process and generation of solid separating layer of stationary thickness on given part of plate area, determined using sharp bend on the curve of temporal dependence of anode current.

EFFECT: gas membrane, produced in accordance to method, has increased penetrability for molecules of light gases and increased selectivity characteristics at room temperature.

2 cl, 3 dwg, 3 ex

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