Method for cleaning silicon substrate surfaces

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

 

The invention relates to the technology of manufacturing semiconductor devices and IP, in particular to the cleaning of the surface of the silicon substrate from the organic and mechanical impurities before thermal operations.

Known methods of cleaning the surface of a silicon substrate, the essence of which consists in the complete removal of organic and mechanical impurities from the surface of the silicon substrate [1, 2].

The disadvantages of the method of surface cleaning of silicon wafers are insufficient removal of various impurities, contaminants from the surface of the silicon substrate and the duration of the process.

A known method of cleaning the surface of a silicon substrate, the essence of which is that the chemical treatment is carried out in a hot solution of peroxide-ammonia solution at room temperature (75-80° (C), hydrogen peroxide (H2About2and Aqua ammonia (NH4OH) [3].

The main disadvantages of this method are the lack of removal of different kinds of pollution (more than 10 pieces of dust), the duration of the process - more than 20 minutes.

The aim of the invention is the complete removal of organic and mechanical impurities, impurities from the surface of the silicon substrate and reducing the time of processing wafers.

The control surface is carried out under a focused beam of light on ICIE dust.

This objective is achieved in that the method of cleaning a silicon substrate includes the two-stage processing in two baths with different solutions:

1. The first bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2About2in the following proportion:

H2SO4:H2About2=10:1 at a temperature of T=125°C;

2. The second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water (H2O) in the ratio of:

NH4OH:H2About2:H2O=1:4:20 at a temperature of T=65°C.

The essence of the method lies in the fact that on the surface of the silicon substrates is the complete removal of organic and mechanical impurities. In the 1st tub removes the most serious grease, in the 2nd bath is removed remaining dissolved in the first treatment plots fat cover.

The proposed method differs from the known fact that the treatment in the acid (H2SO4allows you to remove the adsorbed metal ions and dissolve the oxide film on the semiconductor surface, and perhydrol decomposes with evolution of atomic oxygen: H2O2=N2O+O, and where atomic oxygen oxidize both organic and inorganic contamination. loci accelerates the reaction of decomposition of perhydrol, and also binds to soluble complex compounds.

Summary of the invention the following examples.

Example 1. The process carried out at the facility chemical processing (Lada-1) when the ratio of the components:

the first bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2in the following proportion:

H2SO4:H2O2=8:1, at a temperature of T=125°C

the second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water (H2O) in the ratio of:

NH4OH:H2O2:H2O=1:2:20, at a temperature of T=65°C.

The number of dust particles is 5 pieces.

Example 2. The method is carried out analogously to example 1. The process is carried out at a ratio of components:

the first bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2in the following proportion:

H2SO4:H2O2=9:1 at a temperature of T=125°C,

the second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water (H2O) in the ratio of:

NH4OH:H2O2:H2O=1:3:20 at a temperature of T=65°C.

The number of specks is not b is more 4 pieces.

Example 3. The method is carried out analogously to example 1. The process is carried out at a ratio of components:

the first bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2in the following proportion:

H2SO4:H2O2=8:1, at a temperature of T=125°C,

the second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water (H2O) in the ratio of:

NH4OH:H2About2:H2O=1:2:20, at a temperature of T=65°C.

The number of dust particles is 3 pieces.

As follows from the results of the experiments, one of the most effective solutions for cleaning the surface of silicon substrates is the solution consisting of the following components:

the first bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2in the following proportion:

H2SO4:H2O2=8:1, at a temperature of T=125°C,

the second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water (H2O) in the ratio of:

NH4OH:H2About2:H2O=1:2:20, at a temperature of T=65°C.

Thus, the proposed method is compared with the prototype allows you to clear the flints the first substrate with a purity of not more than 3 pieces and reduce the time of cleaning the surface of silicon wafers.

Literature

1. Production technology of semiconductor devices and integrated circuits. / Edited Aigumov, Win - M.: Higher school", 1986, - s.

2. Technology and design of integrated circuits, microprocessors and microassemblies. / Edited Loukolela. - M.: Radio and communication, 1989, - s.400.

3. Processing of semiconductor materials / edited by Vpopovska, Bailarina. - M, - .183.

The method of cleaning the surface of a silicon substrate, comprising cleaning the surface of a silicon substrate from contamination before thermal operations carried out in two stages, wherein the two-stage treatment is carried out in two different baths: 1 bath contains a solution consisting of sulfuric acid (H2SO4) and hydrogen peroxide (H2About2) in the ratio of components of H2SO4:H2O2=10:1, processing is carried out at a temperature of T=125°and in the second bath contains a solution consisting of aqueous ammonia (NH4OH), hydrogen peroxide (H2About2) and deionized water (H2O) in the ratio of components NH4OH:H2O3:H2O=1:4:20, processing is carried out at a temperature of T=65°C, control of surface roughness of the silicon substrate is performed under a focused beam, where the number of dust particles is not more than three pieces.



 

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