A method of producing silicon multicrystalline

 

(57) Abstract:

The invention relates to semiconductor technology and may find application in industry for the production of a number of discrete semiconductor devices (for example, load cells, field-effect transistors, switches, sensors, small movements and other devices). The proposed method includes the composition of the plate-substrate and the plate-source oriented in the direction of 100 and are arranged with a gap between them of 10 to 40 μm and the misorientation angles of the planes perpendicular to their working surfaces, equal to 1 20°, the formation of the liquid in the gap zone, creating a temperature gradient and subsequent local recrystallization plate - source by scanning the laser beam to exit at the surface of the fragmented zone. Before scanning the laser beam near the surface of the plate - source-side input beam has a filter of IrTran representing a circular plate with a diameter equal to the diameter of the plate - source, effective filter surface equal to the area of a square inscribed in the circumference of the filter, are made through the cracks.

The invention relative to aamah for the manufacture of a number of discrete semiconductor devices (for example, load cells, field-effect transistors, switches, sensors, small movements, and others).

The closest technical solution of the invention is a method of obtaining multicrystalline silicon, comprising a composition of two silicon wafers with a specified gap between them, capillary retraction into the gap of the melt, the formation of a zone of melt and moving it to the temperature gradient through one of the plates to the exit to the surface.

In a known method of producing multicrystalline comprising heating the composition of the plate-substrate and the plate-source oriented in the direction <100> and arranged with a gap between them 10-40 μm and an angle of misorientation of the planes perpendicular to their working surfaces, equal 1-20aboutthe formation of the liquid zone in the gap, creating a temperature gradient and subsequent local recrystallization plate-source by scanning the laser beam to exit at the surface of the fragmented zone (set linear zones) before laser heating plate source near the surface have a filter of istrana (fluoride magnesium - MgF2), which is a round plate with a diameter of, recruiment filter, made through the cracks with the following geometrical parameters: width - h = 100-300 μm, length l = d/, the distance between them is b = 500-1000 μm, and the width of the gap (h) is related to the diameter of the laser beam D ratio h = k D, where k = 0,45-0,63.

The essence of the proposed method of obtaining multicrystalline consists in the following.

The plate-substrate representing a monocrystalline silicon wafer oriented in certain crystallographic directions, combined with single-crystal plate source so that the crystallographic directions of the substrate is <100> be deployed relatively directions <100> plane of the plate-source angle 1-20about; Liquid aluminum area formed by capillary retraction during isothermal aging composition: substrate-source with a capillary gap between the plates. Liquid zone produces a flat with a thickness in the range of 10-40 μm. The fragmentation of the flat zone is carried out by scanning a laser beam along a linear slits in the filter, oriented in the direction of the plate-source scan rate of 200-300 Hz. The need to use the filter absorbing radiation is in the distribution, i.e., on the peripheral regions of the beam energy density is much less than in the center of the beam. And this leads to uneven area to the heating area of the flat zone from which is formed a linear area, creating a migration pathway elements multicrystal. As a result of such heating parallel to the main line area formed by a set of micro-watersheds satellites, migrating through the plate-source and distorting forming region boundaries multicrystal, and subsequently impair their electrophysical properties. The filter containing the slit width h which is less than the diameter of the laser beam D by a specified amount, you can select only the part of the radiation, in which the intensity area of the beam is practically constant, and thereby to eliminate the conditions for mass education microzone satellites. When creating multicrystalline silicon is applied laser radiation in the infrared region with a wavelength of 1060 nm and the oscillation mode of THE00because in this area the silicon is transparent to radiation and all its energy is absorbed by the area. The choice of filter material - IrTran associated with work in this range of the spectrum.

IrTran at the wavelength of 1060 nm passes only 5-7% of the radiation. In addition the program areas of the laser beam with an almost uniform over the area of the radiation intensity with a diameter of 100-300 μm you must use the original laser beam with a diameter of about 200-600 μm.

The topology of the slots on the filter due to: firstly, the need to use the maximum square plate-source as the element base of multicrystal (hence the use of the area of a square inscribed in a circle coinciding with the diameter of the plate-source); secondly, the dimensions between the deformation boundaries multicrystal. The side of the square (a) inscribed in a circle of diameter d, is determined by the ratio a = d/. The length of the slits (l) is set equal to the side of the square (a). The thickness of the filter of IrTran ranged between 1.5-2 mm. However, given the physico-mechanical properties of the material of the filter is the optimal value of its thickness was 1.7 mm

Thus, after receiving the laser beam with a uniform area distribution of the energy of radiation and falling to the flat area is formed of a linear area that stands out from the flat and migrates through the temperature gradient from the plate-substrate through a plate-source to the surface of the latter.

Obtained recrystallized layer inherits the crystallographic properties of the substrate, which allows you to create items multicrystal. Series scopes multicrystal obtained by ora is a filter, with the appropriate topology cracks. After forming the desired number of regions multicrystal stop heating, the workpiece is cooled and the surface of the plate-source zashlifovyvajut post it metal-solvent, and from the opposite side of the composition zashlifovyvajut plate-substrate and remains flat area.

Thus, improving the uniformity of heating across the width of the formed linear zones is achieved by using the filter of IrTran having a linear slit, the topology of which corresponds to the topology generated multicrystal.

Improving the quality of the obtained structures is provided to improve the uniformity of heating that can virtually get rid of the microzone satellites and reduce 3-5 times the density of the inclusions of the second phase.

The temperature and time of process of formation of the flat zone of the solution-melt are typical when working with the system silicon-aluminum. To obtain a flat area can be used a method of introducing a metal-solvent from the end of the song.

The range of the numerical values of the coefficient (k) in the formula connecting the width of the slit in the filter (h) and the diameter of the laser beam (D) is selected on the basis of the former is 100) 60 mm in diameter oriented in the direction <100> and combine them, leaving between them a capillary gap of 10 μm. Put the composition in bigradient furnace, where the temperature of 900-1000aboutWith capillary retraction form liquid aluminum zone. Then the composition is set in a special cassette that contains the filter of istrana, the thickness of 1.76 mm Filter is a circular plate of diameter d = 60 mm In this plate is inscribed a square of side a = d/ = 43 mm = 43 .On the effective area of filter (h) mm2made a slit along one side of a square with a length of 43 mm, a width of 100 μm, located through 500 μm. The filter is oriented so that the direction <100>wafer-source coincided with the direction of the slits. After that, the cassette is placed in a vacuum chamber and a side plate of the source lead of the laser beam, the diameter of which is determined from the formula D = . In this case, h = 100 ám, k = 0.45 and D220 μm. Orient it exactly in the center of the first slit filter and scan with a frequency of 200 Hz along the linear slit oriented along the direction of <100> wafer-source to output a linear area on the surface. Then the laser beam is moved along the surface of the filter until the next slot, which is located from the previous 500 μm, and repeat the operations in the crystal with a diameter of 60 mm is formed 65 working elements forming multicrystal (because really involved area h mm2). Then zashlifovyvajut plate-substrate with the remnants of the flat zone, as well as those on the plate surface of the source metal-solvent and receive the actual multicrystal silicon.

P R I m m e R 2. As the plate-substrate take the silicon wafer with a diameter of 60 mm and a thickness of 300 μm. As the plate-source take the silicon wafer with the same diameter, but the thickness of 1000 μm. Prepare a portion of the aluminum 420 mg. Substrate is disposed on a plate-the source so that the angle between the directions <100> substrate and the source was 20about. The side have a portion of the aluminum. Put the composition in bigradient oven and maintained at a temperature of 1000aboutWith over 10 min, where the capillary is formed by drawing the liquid zone. Then, the resulting composition is placed in the cartridge, where is the filter of IrTran thickness of 1.7 mm, with a linear slit width of 200 μm and located through 800 μm from each other. Moreover, the direction of the slits coincide with the directions <100>wafer-source. Then the cartridge is placed in a vacuum chamber, to lectromagnetic the scanner scans the laser beam along the direction of <100> from the filter, to output liquid line area on the surface. The scanning frequency of 250 Hz. Then move the laser beam at a distance of 800 μm to the next slot on the filter, repeat the scan and get multicrystal containing 40 work items.

P R I m e R 3. The difference of this example from the previous is that the filter has a slit 300 microns, located over 1000 microns.

The filter diameter as the diameter of the compositions 76 mm Therefore, the effective area is h mm2. The diameter of the laser beam in this case D 476 μm (because k = 0,63). In this example, it turns out 41 work item multicrystal.

The use of mutual orientation of the silicon wafer (substrate and source), the filter of IrTran absorbing radiation in the IR range, and the laser radiation received multicrystal containing the required number of work items that can be used in the manufacture of load cells, field-effect transistors, switches, etc. Metallographic examination of the samples showed that the amount of multicrystal completely no large inclusions ( 5 μm) of the second phase, and the density of small inclusions (< 5 μm) reduced in 3-5 Cristallo SILICON, comprising heating the composition of the plate-substrate and the plate-source oriented in the direction <100> and arranged with a gap between them, forming in the gap of the liquid zone and the recrystallization of the plate-source by moving zone in the temperature gradient across the plate source to output on its surface, characterized in that sets the gap between the plates the size of 10-40 μm, and the misorientation angles of the planes perpendicular to the working surfaces of the plates 1-20oliquid zone is moved by the scanning laser beam before crystallization at the surface of the plate-source-side of the laser beam is placed round the plate filter of IrTran MgFr diameter equal to the diameter of the plate-source, and with an effective surface equal to the square inscribed in a circle of filter square, on this surface izgotovlivajut through slit a length and width equal to kD , of the interval 100-300 μm, with the distance between 500-1000 μm, where d is the diameter of the filter, D is the diameter of the laser beam, K= 0,46-0,63 - factor, taking into account the uniformity of the energy density by the area of the laser beam.

 

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