JP2005108889A - Method of manufacturing semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor substrate of high quality with high yield by optimizing the grain diameter of abrasive grains and density of a slurry used for slicing. <P>SOLUTION: In the semiconductor substrate manufacturing method, a semiconductor ingot is sliced into semiconductor substrates with a multi-wire saw device as the slurry composed of SiC abrasive grains and lapping oil is fed from a slurry feeder. The abrasive grains corresponding to NO.700 to NO. 1200 specified by JIS R 6001 are used for the slurry, and the density of the abrasive grains in the slurry is set to ≥1.3 g/cc to and ≤2.0 g/cc. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a method for manufacturing a semiconductor substrate in which a semiconductor ingot is sliced with a multi-wire saw device to form a semiconductor substrate for a solar cell.

  Conventionally, when a semiconductor substrate for a solar cell is formed of polycrystalline silicon or the like, for example, a polycrystalline silicon ingot is formed by a casting method, and the ingot is cut into a predetermined size to form a semiconductor ingot. Was sliced into a plurality of pieces with a multi-wire saw device.

  FIG. 1 is a diagram for explaining a semiconductor substrate forming apparatus and a slurry supply apparatus in the semiconductor forming apparatus for explaining a conventional technique and a method for manufacturing a semiconductor substrate according to the present invention.

  As shown in FIG. 1, the multi-wire saw apparatus used when slicing a semiconductor ingot fixes the semiconductor ingots 3a and 3b, and supplies slurry from several places above when slicing them. For example, a plurality of piano wire wires 6 are stretched at a predetermined interval on a main roller 5 made of urethane resin or the like (see, for example, Patent Document 1).

  That is, when slicing the semiconductor ingots 3a and 3b, slurry containing mixed abrasive grains is supplied from the slurry supply devices 2a, 2b and 2c, and a plurality of wires 6 stretched between two rollers 5 are rotated at high speed. However, the semiconductor ingots 3a and 3b are sliced by gradually lowering the plurality of semiconductor ingots 3a and 3b to the wire 6 portion.

In addition, the slurry supplied at this time is temporarily stored in the dip tank 8, and is continuously conveyed again to the slurry supply devices 2a, 2b, 2c through the slurry supply nozzles 1a, 1b, 1c, Sequentially supplied without interruption. At this time, the semiconductor ingots 3a, 3b are set, for example, in two rows of semiconductor ingots 3a, 3b between the main rollers 5 in the slice region, and slice a plurality of semiconductor ingots 3a, 3b at a time.
JP 7-106288 A

  However, in this conventional semiconductor substrate forming apparatus, when the semiconductor ingots 3a and 3b are sliced, for example, there are slurry supply devices 2a, 2b and 2c, respectively, between both ends of the semiconductor ingots 3a and 3b set in two rows. The slurry supplied to the slurry supply devices 2a, 2b, and 2c is composed of SiC abrasive grains and wrapping oil composed of mineral oil, surfactant, and dispersing agent. Due to the change in weight (hereinafter referred to as slurry density), the amount of abrasive grains in the slurry to one semiconductor ingot changes, resulting in wire rubbing traces and irregularities during cutting on the semiconductor substrate, resulting in poor surface conditions. There is a problem that the quality of the semiconductor substrate varies.

  Further, since the cutting load when slicing the ingots 3a and 3b is increased in both the insufficient density region and the excessive region of the slurry, the frictional heat generated during the cutting increases, and the slurry temperature rises greatly, so that a stable slurry temperature cannot be obtained. There was also.

  When the slurry temperature rises, when the main roller is made of urethane resin or the like, problems such as a decrease in durability and an increase in the degree of wear occur. Furthermore, since the viscosity of the slurry is reduced and the adhesiveness of the abrasive grains to the wire is reduced, the ingot's machinability is reduced, the wire is broken, and the surface state of the cut surface of the sliced wafer becomes poor. Occurs.

  The present invention has been made in view of such conventional problems, and by optimizing the particle size and slurry density of the abrasive grains used for slicing, a high-quality semiconductor substrate can be obtained at a high yield. An object is to provide a method of forming.

  In order to achieve the above object, in the method for manufacturing a semiconductor substrate according to claim 1 of the present invention, a semiconductor ingot is supplied with a multi-wire saw device while supplying slurry comprising SiC abrasive grains and wrapping oil from the slurry supply device. In the semiconductor substrate manufacturing method of slicing to form a semiconductor substrate, the slurry uses abrasive grains equivalent to 700 to 1200 in accordance with JIS standard R6001, and the abrasive grains in the slurry It is characterized by being used at a density of 1.3 g / cc or more and 2.0 g / cc or less.

  Further, the slurry uses abrasive grains of 700 or more and less than 900 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.3 g / cc or more and 1.8 g / cc or less. Should be.

  Further, the slurry uses abrasive grains of 900 to 1200 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.5 to 2.0 g / cc. There may be.

  According to the method for manufacturing a semiconductor substrate according to claim 1 of the present invention, a semiconductor substrate is sliced with a multi-wire saw device while supplying a slurry made of SiC abrasive grains and wrapping oil from a slurry supply device. In the method for producing a semiconductor substrate to be formed, abrasives equivalent to 700 or more and 1200 or less as defined in JIS standard R6001 are used for the slurry, and the density of the abrasive grains in the slurry is 1.3 g / It is used at cc or more and 2.0 g / cc or less.

  By doing in this way, the supply amount of the abrasive grains in the slurry to one semiconductor ingot is stabilized from the cutout portion to the cut end portion, and a semiconductor substrate having a good surface state can be stably formed.

  Moreover, while using abrasive grains of 700 or more and less than 900 as defined in JIS standard R6001, the density of the abrasive grains in the slurry is 1.3 g / cc or more and 1.8 g / cc or less. By doing so, the supply amount of abrasive grains in the slurry to one semiconductor ingot from the cut-out portion to the cut-out end portion can be stabilized, and a semiconductor substrate having a good surface state can be stably formed, and the slurry can be formed. Since it can be used repeatedly, productivity is improved. At this time, particularly by setting the density of the abrasive grains to 1.4 g / cc or more and 1.8 g / cc or less, a higher slice yield can be secured stably.

  Furthermore, the abrasive grains of 900 to 1200 as defined in JIS standard R6001 are used for the slurry, and the density of the abrasive grains in the slurry is 1.5 g / cc to 2.0 g / cc. By doing so, the supply amount of abrasive grains in the slurry to one semiconductor ingot from the cut-out part to the cut-off end part can be stabilized, and a semiconductor substrate having a good surface state can be stably formed, Since the particle size is small, the margin for slicing the ingot can be reduced. Further, the surface state of the semiconductor substrate that is cut out can be formed more smoothly than when abrasive grains having a large particle diameter are used, and variations in the thickness of the semiconductor substrate in the surface and in the ingot can be suppressed.

  Further, at this time, particularly by setting the density of the abrasive grains to 1.6 g / cc or more and 2.0 g / cc or less, a higher slice yield can be stably secured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 2 is a diagram for explaining the flow of slurry in the length direction of a semiconductor ingot of a semiconductor substrate forming apparatus for explaining a method for producing a semiconductor substrate according to the present invention, and FIG. 3 is a semiconductor according to the present invention. FIG. 4 is a graph showing a result of an example when slicing is performed by a substrate forming method, and is a graph for explaining a correlation between slurry density and slice yield; FIG. 4 is a method for forming a semiconductor substrate according to the present invention; It is a graph which shows the result of the other Example at the time of slicing, and is a graph for demonstrating the correlation of a slurry density and a slice yield.

  The basic structure of the semiconductor substrate forming apparatus according to the present invention is the same as that of the conventional apparatus shown in FIG. That is, slurry supply devices 2a, 2b and 2c are provided below the slurry supply nozzles 1a, 1b and 1c, and the semiconductor ingots 3a and 3b bonded to the slicing base 4 are provided between the slurry supply devices 2a, 2b and 2c. The semiconductor ingots 3a and 3b are arranged and sliced by the piano wire 6 between the plurality of main rollers 5 while being gradually lowered. In FIG. 1, reference numeral 7 denotes an end material entanglement preventing plate, and 8 denotes a dip tank. The slurry is composed of, for example, a mixture of abrasive grains and wrapping oil composed of mineral oil, a surfactant, and a dispersant. Also, a plate 7 is provided to prevent the end of the semiconductor substrate that may fall during slicing from entering the main roller, and a dip tank 8 is provided to receive the end of the semiconductor substrate that may fall. ing.

  The semiconductor ingots 3a and 3b are constituted by, for example, a polycrystalline silicon ingot formed by a casting method or the like cut into a predetermined dimension. An adhesive or the like is applied to one surface of the semiconductor ingots 3a and 3b and bonded to the base material 4 made of carbon or glass. Therefore, the semiconductor ingots 3a and 3b are sliced so as not to fall apart and are put into the next cleaning step.

  The piano wire 6 is composed of a piano wire having a diameter of about 140 to 180 μm, for example, and is arranged at a pitch of about 400 to 600 μm. This wire travels at a high speed of about 500 to 800 m / Min.

  Above the semiconductor ingots 3a and 3b, slurry supply nozzles 1a, 1b and 1c for supplying a slurry for slicing are provided, and slurry supply devices 2a, 2b and 2c are provided below the slurry supply nozzles 1a, 1b and 1c. Is provided.

  In the example shown in FIG. 1, two rows of semiconductor ingots 3a and 3b are installed, and slurry is supplied to the semiconductor ingots 3a and 3b installed in two rows even when the wire 6 travels in either the right direction or the left direction. Three slurry supply nozzles 1a, 1b, and 1c are provided so that the slurry can be supplied, and three slurry supply devices 2a, 2b, and 2c are further provided so that the slurry can be evenly supplied to the wires 6 stretched over a plurality of wires. Yes.

  In the present invention, in the method of manufacturing a semiconductor substrate in which a semiconductor substrate is formed by slicing a semiconductor ingot with a multi-wire saw device while supplying a slurry comprising SiC abrasive grains and wrapping oil from a slurry supply device, Abrasive grains corresponding to No. 700 or more and No. 1200 or less as defined in the standard R6001 are used, and the density of the abrasive grains in the slurry is 1.3 g / cc or more and 2.0 g / cc or less.

  By doing in this way, the supply amount of the abrasive grains in the slurry to one semiconductor ingot is stabilized from the cutout portion to the cut end portion, and a semiconductor substrate having a good surface state can be stably formed.

  The count of the abrasive grains is a count specified by JIS R6001 (grain size of abrasive for grinding wheel) revised on November 20, 1998, and is a test of JIS R6002 (test method for grain size of abrasive for grinding wheel). It is measured based on the method. JIS R6001 only describes Nos. 700, 800, 1000, and 1200, but based on the method of determining the JIS number, the same abrasive grains as those passed through a sieve having a mesh number of 700 to 1200 per parallel inch Becomes the abrasive grains used in the present invention.

  At this time, if the number of abrasive grains less than 700 is used, the abrasive grain size becomes large, so that scratches, steps, etc. are likely to occur on the surface of the semiconductor substrate. Wire consumption is promoted, leading to reduced machinability. Further, the cutting margin becomes large, so the productivity is lowered. Furthermore, when the slurry density is adjusted to the present invention, the number of abrasive grains contained in the slurry per unit amount is reduced, and the supply amount of abrasive grains in the slurry to one semiconductor ingot is stable from the cut-out portion to the end-of-cut portion. Without leading to a decrease in machinability.

  On the other hand, if the number of abrasive grains exceeding 1200 is used, the grain size is too fine and the abrasive grains adhering to the wire are clogged during cutting, and the cutting efficiency is lowered because the abrasive grains do not rotate efficiently. Further, when the slurry density is adjusted to the present invention, the number of abrasive grains contained in the slurry per unit amount increases, so that the heat exchange rate of the slurry during cutting is poor and the slurry temperature is likely to increase. If the main roller is made of urethane resin or the like when the slurry temperature rises, problems such as a decrease in durability of the main roller or an increase in the degree of wear occur. Furthermore, since the viscosity of the slurry is reduced and the adhesiveness of the abrasive grains to the wire is reduced, the ingot's machinability is reduced, the wire is broken, and the surface state of the cut surface of the sliced wafer becomes poor. Occurs.

  Moreover, when the mass density of the abrasive grains in the slurry is less than 1.3 g / cc, the abrasive grains are insufficient during the cutting, and the cutting ability such as the abrasive grains are not uniformly supplied from the start of the ingot to the end of the cutting. A problem occurs.

  Conversely, when the mass density of the abrasive grains in the slurry exceeds 2.0 g / cc, the heat exchange rate of the slurry during cutting is poor and the slurry temperature is likely to increase. If the main roller is made of urethane resin or the like when the slurry temperature rises, problems such as a decrease in durability of the main roller or an increase in the degree of wear occur. Furthermore, since the viscosity of the slurry is reduced and the adhesiveness of the abrasive grains to the wire is reduced, the ingot's machinability is reduced, the wire is broken, and the surface state of the cut surface of the sliced wafer becomes poor. Will occur.

  At this time, the slurry uses abrasive grains of 700 or more and less than 900 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.3 g / cc or more and 1.8 g / cc or less. You should have it.

  Abrasive grains are obtained by baking and solidifying quartz, tar, and salt, primary grinding with a ball mill, and secondary grinding with another ball mill or secondary grinding with a jet mill. The primary pulverization is coarse pulverization, and the secondary pulverization is main pulverization. Apply coarse pulverization, select the particle size by sieving, and then apply the main pulverization. The primary pulverization is simply pulverization of a large lump, and the secondary pulverization is to further reduce the size to a uniform size. In other words, the pulverization time is shortened to obtain abrasive grains with a large particle size, and the pulverization time is lengthened to obtain abrasive grains with a small particle size.

  Due to the manufacturing method of such abrasive grains, large abrasive grains having a particle size of 700 or more and less than 900 are less excessively pulverized, so that the acicular degree of the abrasive grains (absolute maximum length / diagonal width) is large on the surface. Since there are many irregularities, machinability is good. Further, the abrasive grains can be used repeatedly for a long time. As a result, the supply amount of abrasive grains in the slurry to one semiconductor ingot from the cut-out portion to the end-of-cut portion is stabilized, and a semiconductor substrate having a good surface state can be stably formed, and the slurry is repeatedly used. Productivity is improved.

  At this time, if the slurry density is less than 1.3 g / cc, there will be insufficient abrasive grains during cutting, and abrasive grains will not be supplied uniformly from the start of the ingot to the end of cutting, causing a problem of machinability. .

  Conversely, if it exceeds 1.8 g / cc, the heat exchange rate of the slurry during cutting is poor and the slurry temperature is likely to rise. If the main roller is made of urethane resin or the like when the slurry temperature rises, problems such as a decrease in durability of the main roller or an increase in the degree of wear occur. Furthermore, since the viscosity of the slurry is reduced and the adhesiveness of the abrasive grains to the wire is reduced, the ingot's machinability is reduced, the wire is broken, and the surface state of the cut surface of the sliced wafer becomes poor. Occurs.

  The slurry uses abrasive grains of 900 to 1200 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.5 g / cc to 2.0 g / cc. May be.

  By making the grain size of the abrasive grains from 900 to 1200, a semiconductor substrate in which the amount of abrasive grains in the slurry to the semiconductor ingot from the cut-out portion to the cut-out end portion is stable and the surface state is good Can be formed stably, and since the particle size is relatively small, the margin for slicing the ingot can be reduced. Further, the surface state of the semiconductor substrate that is cut out can be formed more smoothly than when abrasive grains having a large particle diameter are used, and variations in the thickness of the semiconductor substrate in the surface and in the ingot can be suppressed.

  At this time, if the slurry density is less than 1.5 g / cc, there will be a problem of machinability such that the abrasive grains are insufficient during cutting and the abrasive grains are not supplied uniformly from the start of the ingot to the end of cutting.

  Conversely, if it exceeds 2.0 g / cc, the heat exchange rate of the slurry during cutting is poor and the slurry temperature is likely to rise. If the main roller is made of urethane resin or the like when the slurry temperature rises, problems such as a decrease in durability of the main roller or an increase in the degree of wear occur. Furthermore, since the viscosity of the slurry is reduced and the adhesiveness of the abrasive grains to the wire is reduced, the ingot's machinability is reduced, the wire is broken, and the surface state of the cut surface of the sliced wafer becomes poor. Occurs.

Two semiconductor ingots of 150 mm square * L = 280 mm were set in the semiconductor substrate forming apparatus shown in FIG. 1, and a piano wire having a diameter of 180 μm was run at high speed and sliced continuously. Table 1 shows the results of examining the slurry temperature and the slice yield by changing the average particle size of the slurry at this time between 10 and 17 μm. The supply amount of the slurry at this time was 100 liters / min.

As can be seen from the table, regardless of the slurry density (in both 1.3 cc / g and 2.0 cc / g), high yield is achieved under conditions of 700 to 1200 as defined in JIS standard R6001. It turns out that it is obtained.

Next, using a No. 800 abrasive grain, changing the slurry density, two 150 mm square * L = 280 mm semiconductor ingots were set in the semiconductor substrate forming apparatus shown in FIG. 1, and a piano wire having a diameter of 180 μm Was run at high speed and sliced continuously. The relationship between the slurry density and the slice yield at this time is shown in FIG.

  As can be seen from FIG. 3, by making the slurry density 1.3 g / cc or more and 1.8 g / cc or less, a slice yield of 90% or more can be stably obtained. Further, as apparent from Table 2, a high yield of 97% or more could be stably ensured particularly by setting the slurry density to 1.4 g / cc or more and 1.8 g / cc or less.

Furthermore, using a 1000th abrasive grain, changing the slurry density, two 150 mm square * L = 280 mm semiconductor ingots were set in the semiconductor substrate forming apparatus shown in FIG. 1, and a piano wire having a diameter of 180 μm Was run at high speed and sliced continuously. The relationship between the slurry density and the slice yield at this time is shown in FIG.

  As can be seen from Table 3, by setting the slurry density to 1.5 g / cc or more and 2.0 g / cc or less, a slice yield of 90% or more can be stably obtained. Further, as clearly shown in Table 3, a high yield of 97% or more could be stably ensured particularly by setting the slurry density to 1.6 g / cc or more and 1.8 g / cc or less.

It is a figure for demonstrating the slurry supply apparatus in the formation apparatus of a semiconductor substrate, and a semiconductor formation apparatus for demonstrating the manufacturing method of the semiconductor substrate which concerns on a prior art and this invention. It is a figure for demonstrating the flow method of the slurry of the length direction of the semiconductor ingot of the semiconductor substrate formation apparatus for demonstrating the manufacturing method of the semiconductor substrate which concerns on this invention. It is a graph which shows the result of one Example when slicing with the manufacturing method of the semiconductor substrate which concerns on this invention, and is a graph for demonstrating the correlation of a slurry density and a slice yield. It is a graph which shows the result of the other Example when slicing with the manufacturing method of the semiconductor substrate which concerns on this invention, and is a graph for demonstrating the correlation of a slurry density and a slice yield.

Explanation of symbols

1a, 1b, 1c ... slurry supply nozzles 2a, 2b, 2c ... slurry supply devices 3a, 3b ... semiconductor ingot 4 ... slice base 5 ... main roller 6 ... wire 7 ... -End material entrainment prevention plate 8 ... Dip tank 9, 10 ... Slurry supply end (left and right)

Claims (3)

In a semiconductor substrate manufacturing method in which a semiconductor substrate is formed by slicing a semiconductor ingot with a multi-wire saw device while supplying a slurry made of SiC abrasive grains and wrapping oil from a slurry supply device, the slurry is specified by JIS standard R6001. The semiconductor is characterized in that the abrasive grains corresponding to 700 to 1200 are used, and the density of the abrasive grains in the slurry is 1.3 g / cc to 2.0 g / cc. A method for manufacturing a substrate. The slurry uses abrasive grains of 700 or more and less than 900 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.3 g / cc or more and 1.8 g / cc or less. The method of manufacturing a semiconductor substrate according to claim 1. The slurry uses abrasive grains of 900 to 1200 as defined in JIS standard R6001, and the density of the abrasive grains in the slurry is 1.5 g / cc to 2.0 g / cc. The method of manufacturing a semiconductor substrate according to claim 1.

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