JP5213037B2 - Semiconductor manufacturing method and semiconductor manufacturing apparatus - Google Patents

Description

  The present invention relates to a semiconductor manufacturing base plate and a semiconductor manufacturing method.

  Conventionally, polycrystalline silicon has been manufactured by pouring a silicon melt into a mold and gradually cooling it, and slicing the obtained polycrystalline ingot. Therefore, the loss of silicon due to slicing and the cost for slicing have been problems.

  Patent Document 1 proposes a method that does not require slicing and enables mass production of a polycrystalline silicon wafer at low cost. This method is a method for producing a silicon sheet for a solar cell directly from a silicon melt, wherein a substrate having an uneven portion is cooled, and the surface of the cooled uneven portion of the substrate is brought into contact with the silicon melt. A silicon sheet is obtained by preferentially generating and growing crystal nuclei at the tip of a convex part of a substrate having a concavo-convex part, and growing by connecting crystals grown from adjacent tip parts. is there.

  The method described in Patent Document 2 is a method of manufacturing a solid phase sheet of silicon by bringing a substrate having a growth surface into contact with a silicon melt and growing silicon on the substrate. By the peripheral groove, the peripheral portion located outside the peripheral groove and the solidified growth surface of the solid-phase sheet are obtained in a state separated from each other, In the product sheet formed on the inner side, a sheet having a uniform thickness can be obtained.

The method described in Patent Document 3 is a plate-like silicon in which a substrate is immersed in a silicon melt and crystal is grown on the immersion surface of the substrate. A plane, and at least one other plane that is continuous and crystal-grown on the side surface of the substrate, etc., and the normal vector of the other plane is antiparallel or obtuse with the normal vector of the first plane, The first surface and other surfaces are formed with engaging portions between the substrate and the plate-like silicon to prevent the plate-like silicon from dropping from the substrate when the plate-like silicon is manufactured.
JP 2001-223172 A JP 2002-0237465 A International Publication No. 04/016836 Pamphlet

  When the substrate was immersed in a silicon melt and the plate-like silicon grown on the substrate was taken out of the chamber, there was plate-like silicon whose front side in the immersion direction was cracked. Further, the larger the size of the substrate, the easier it was to break. When it is cracked, it may not be possible to cut into a predetermined size for a silicon substrate for a solar cell, which leads to a decrease in yield, and therefore reduction of the crack has been desired. Moreover, if the warpage of the plate-like silicon cut out to a predetermined size is large, the solar cell manufacturing process becomes difficult, and thus reduction of the warpage has been desired.

  The present invention provides a plate-like semiconductor with reduced cracks and warpage.

  The present invention relates to a semiconductor manufacturing base plate for use in a semiconductor manufacturing method in which a base plate having a growth surface is immersed in a semiconductor melt and a semiconductor is grown on the base plate. The surface has a groove extending from the front part in the immersion direction to the rear part.

  In the base plate for manufacturing a semiconductor according to the present invention, the groove is preferably substantially parallel to the immersion direction.

The base plate for semiconductor production according to the present invention preferably has two or more grooves.
The present invention provides a semiconductor manufacturing method in which a base plate having a growth surface is immersed in a semiconductor melt and a semiconductor is grown on the base plate, and the base plate for semiconductor manufacturing is used as the base plate. To do.

  The plate-like semiconductor according to the present invention is manufactured using the semiconductor manufacturing method.

  The present invention further relates to a solar battery cell produced by cutting off the slit portion of the plate-like semiconductor.

  According to the present invention, it is possible to reduce cracks that occur during the process of manufacturing a plate-like semiconductor. Further, the warpage of the plate-like semiconductor can be reduced.

<Base plate and semiconductor for semiconductor production>
A base plate for semiconductor production (hereinafter also referred to as a base plate) of the present invention will be described with reference to FIG. FIG. 1A is a base plate for manufacturing the plate-shaped semiconductor of FIG. In the base plate, the main surface S1 has a crystal growth surface, and a groove that is continuous from the side surface of the immersion direction is formed on the crystal growth surface. FIG. 1B is a cross-sectional view of the base plate taken along the alternate long and short dash line X1a passing through the groove of FIG.

  FIG. 2A is a schematic perspective view of a plate-like semiconductor produced by immersing the base plate in a semiconductor melt, and S2 is a main surface of the plate-like semiconductor. FIG. 2B is a cross-sectional view of the plate-like semiconductor when cut by a dashed line X2a passing through the slit of FIG. A slit of the plate-like semiconductor is formed at the groove portion of the base plate for semiconductor manufacture. As shown in FIG. 2, the warpage of the plate-shaped semiconductor is reduced by manufacturing the plate-shaped semiconductor in which the front portion of the plate-shaped semiconductor in the traveling direction of the base plate is divided.

  The reason why the warpage of the plate-like semiconductor according to the present invention is reduced is presumed to be that the residual stress concentrated on the front portion in the traveling direction of the plate-like semiconductor is divided by the slits.

  The reason why the residual stress concentrates on the front portion in the traveling direction of the plate-like semiconductor is considered to be because the plate thickness of the front portion in the traveling direction of the plate-like semiconductor becomes thicker than other portions.

  As one of the reasons for increasing the plate thickness, since the semiconductor melt enters the semiconductor melt from the front part in the advancing direction of the base plate for semiconductor manufacture, the bottom part for semiconductor manufacture when the front part in the advancing direction is immersed compared to the rear part in the immersion direction It is conceivable that the temperature of the ground plane is low and the growth rate of the plate-like semiconductor is high.

  In addition, when the base plate is pulled up from the semiconductor melt, the plate-shaped semiconductor is pulled up from the semiconductor melt while the semiconductor melt is attached to the plate-shaped semiconductor. The amount of the semiconductor melt pulled up while adhering to the plate-like semiconductor is larger than that of the semiconductor. It is considered that the greater the amount of melt that is pulled up, the greater the effect of solidification shrinkage and the greater the residual stress. In addition, when the melt on the crystallized plate is solidified after coming out of the melt in the crucible, the melt is rapidly solidified and causes strain, so it comes out of the melt in the crucible. It is considered that as the amount of solidification later increases, the surface temperature at the time of solidification decreases and the strain increases and the residual stress increases.

  Based on these assumptions, in the method for producing a plate-like semiconductor in which a base plate for semiconductor production is immersed in a semiconductor melt, the front side in the immersion direction in the plane of the plate-like semiconductor is divided by a slit, so that the size of the portion where residual stress occurs It can be considered that warping can be reduced and cracking can be prevented by dividing the residual stress. This is because the residual stress greatly depends on the size, as warpage and cracking did not become a problem when the size of the base plate for semiconductor fabrication is small.

  The number of grooves in FIG. 1 is not necessarily one. On the contrary, since the residual stress of the manufactured plate-like semiconductor is reduced by the plurality, it is preferable that the number of grooves is two or more. Further, it is desirable that the positions of the grooves are equally spaced. Further, as the length of the groove in FIG. 1 is longer, the residual stress of the plate-like semiconductor is reduced and the warpage is also reduced. However, when the length of the groove is increased, the length of the slit of the plate-like semiconductor is also increased. Therefore, in the case of a continuous product, the area that can be used as the product is reduced. Therefore, it is preferable to determine the length of the groove from the stress relaxation and the reduction of warpage due to the slit and the area available as a product.

  It is preferable that the groove | channel of FIG. 1 is connected from the side surface ahead of the immersion direction. This is because the stress relaxation of the growing plate-like semiconductor becomes larger.

  The grooves in FIG. 1 are preferably parallel to the immersion direction. This is because if the groove has a large angle with respect to the immersion direction, the semiconductor melt accumulates around the groove and causes a defect.

  The groove width W1 is preferably 0.5 mm or more and 5 mm or less. This is because if the width of the groove is 0.5 mm or less, the plate-shaped semiconductor cannot be divided by the plate-shaped semiconductor grown from both sides of the groove. In addition, when the thickness is 5 mm or more, the semiconductor melt enters the groove and the plate-shaped semiconductor cannot be divided. Further, the depth D1 of the groove is desirably 1 mm or more. This is because if the groove depth is 1 mm or less, the semiconductor melt enters the groove portion, and the plate-like semiconductor cannot be divided. In addition, the residual stress of the obtained plate-shaped semiconductor becomes smaller when the number of grooves is larger. However, if the distance between the grooves is less than 1 mm, there is a problem in the durability of the base plate. Therefore, the distance between the grooves should be 1 mm or more. is necessary.

  Next, the side surface on the front side in the immersion direction of the base plate for semiconductor production will be described. 3, 5, and 6 are schematic perspective views of the base plate for semiconductor manufacturing according to the present invention. The side surface preferably has the shape described in Patent Document 3 so that the plate-shaped semiconductor does not fall when the grown plate-shaped semiconductor is pulled up from the semiconductor melt, and according to the present invention, more preferably, It is preferable that the side surface F3 also has a groove for dividing the plate-like semiconductor.

  FIG. 4A is a view of the main surface of a plate-like semiconductor obtained by immersing the base plate for manufacturing semiconductor shown in FIG. 3 in a semiconductor melt. FIG. 4B shows the state in which the semiconductor manufacturing base plate of FIG. 3 is immersed in a semiconductor melt, and the state where the plate-like semiconductor has grown on the semiconductor manufacturing base plate is cut at the position of the dotted line X3a in FIG. It is sectional drawing of a plate-shaped semiconductor and a base plate for semiconductor manufacture. 4C is a cross-sectional view of the semiconductor manufacturing base plate of FIG. 3 immersed in a semiconductor melt and the grown plate semiconductor cut at the position of the dotted line Y3a in FIG. The warpage is reduced by using a plate-shaped semiconductor in which the front portion of the plate-shaped semiconductor shown in FIG. More preferably, it is also preferable that the plate-like semiconductor that grows on the side surface portion in front of the immersion direction that is continuous with the main surface of the plate-like semiconductor is also divided by the slits. The reason why the residual stress is concentrated on the front part of the traveling direction of the plate-like semiconductor is not limited to the reason described with reference to FIGS. Since the plate-like semiconductor having the front surface in the direction has a three-dimensional structure, it is considered that the residual stress at the front portion in the traveling direction of the plate-like semiconductor further increases. Further, in FIG. 3, there is a groove V3 for separating the peripheral plate-shaped semiconductor from the peripheral portion, but this makes it possible to separate the main surface and the side surface portion of the grown plate-shaped semiconductor, and the peripheral portion is thermally contracted. The crack by doing can be prevented.

  For comparison, a conventional plate semiconductor will be described. FIG. 7 is a schematic perspective view of a conventional plate semiconductor, and FIG. 8A is a diagram in which the semiconductor manufacturing base plate of FIG. 7 is immersed in a semiconductor melt, and the plate semiconductor is grown on the semiconductor manufacturing base plate. FIG. 8 is a cross-sectional view of a plate-like semiconductor and a base plate for semiconductor manufacture when the state is cut at a position of a dotted line X7a in FIG. FIG. 8B is a cross-sectional view when the base plate for semiconductor manufacture of FIG. 7 is immersed in a semiconductor melt and the grown plate-shaped semiconductor is cut at the position of the dotted line Y7a in FIG.

  Next, the main surface of the base plate for semiconductor manufacturing will be described. It is preferable that at least fine irregularities are formed on the plate-like semiconductor growth surface of the base plate for semiconductor manufacture in FIGS. 1, 3, 5, 6, and 7. This is because it is possible to stabilize the shape of the obtained plate-shaped semiconductor by providing regular irregularities on the surface of the base plate so that semiconductor crystal nuclei are likely to be generated in advance. It is. Crystals grown from adjacent convex portions are connected to form a plate-like semiconductor. The distance between the convex portions is preferably 0.2 mm or more and 3 mm or less. It is because the crystal grain of the obtained plate-shaped semiconductor will become small as it is less than 0.2 mm, and the characteristic as a semiconductor will worsen. On the other hand, when the thickness is larger than 3 mm, when an attempt is made to produce a plate-like semiconductor without a through hole, the thickness of the averaged plate of the plate-like semiconductor becomes very thick, and the material is wasted. Further, the tip angle of the convex portion is preferably 90 ° to 170 °. If the tip angle is less than 90 °, the semiconductor melt can easily enter the recess, and the resulting plate-like semiconductor has large irregularities. If the tip angle is greater than 170 °, crystal nuclei are also formed in the convex peripheral portion.

<Plate semiconductor manufacturing equipment>
An apparatus for manufacturing a plate-like semiconductor will be described. The apparatus for obtaining a plate-like semiconductor of the present invention is particularly effective when the apparatus shown in FIG. 9 is used. However, the apparatus for realizing the present invention is not limited to this. FIG. 9 shows a schematic cross-sectional view in the production apparatus for producing the plate-like semiconductor of the present invention.

  The plate-like semiconductor manufacturing apparatus shown in FIG. 9 includes a semiconductor manufacturing base plate C (hereinafter also referred to as base plate C), a crucible 111, a heater 112, a raw material melt 113, a crucible base 114, a heat insulating material 115, and a crucible lifting / lowering. A table 116, a shaft 117 fixed to the base plate, and a fixing base 118 for holding the base plate are provided, and the plate-like semiconductor S is formed on the base plate C.

  As shown in FIG. 9, the base plate C below the raw material melt temperature is immersed in the raw material melt 113 in the crucible 111 from the left side in the figure. At this time, the raw material melt 113 is held above the melting point by the heater 112. In order to stably obtain the plate-like semiconductor S, it is necessary to have an apparatus configuration capable of strictly controlling the melt temperature, the atmospheric temperature in the chamber, and the temperature of the base plate C.

  The base plate C is preferably provided with a structure in which temperature control can be easily controlled. The material of the base plate is not particularly limited, but is preferably a material with good thermal conductivity or a material with excellent heat resistance. For example, high-purity graphite, silicon carbide, quartz, boron nitride, alumina, zirconium oxide, aluminum nitride, metal, or the like can be used, but an optimal material may be selected according to the purpose. High-purity graphite is more preferable because it is a relatively inexpensive material that is rich in workability. The material of the base plate can be appropriately selected in consideration of various characteristics such as industrial inexpensiveness and base plate quality of the obtained plate-shaped semiconductor. Further, when a metal is used for the base plate, there is no particular problem as long as the metal is used at a temperature below the melting point of the base plate, such as constantly cooling, and does not significantly affect the properties of the obtained plate-like semiconductor.

  In order to facilitate temperature control, it is convenient to use a fixing base 118 for holding a copper base plate. The fixed base 118 refers to a portion connecting the shaft 117 and the base plate C. The fixing base 118 and the base plate C may be connected to a cooling means. This is because it is easier to adjust the temperature of the base plate C by being connected to the cooling mechanism. Further, a heating mechanism for heating the base plate C may be provided. That is, the base plate C may include a cooling mechanism and a heating mechanism. When the base plate enters the raw material melt, the plate-like semiconductor S grows on the surface of the base plate. Thereafter, the base plate escapes from the raw material melt, but the base plate side receives heat from the raw material melt, and the temperature of the base plate tends to increase. However, if the same base plate is subsequently immersed in the raw material melt at the same temperature, a cooling mechanism for lowering the temperature of the base plate is required. That is, it is preferable that the base plate once escaped from the raw material melt is cooled by the cooling mechanism and then the temperature of the growth base plate is controlled using the heating mechanism before being immersed in the raw material melt. The heating mechanism may be a high frequency induction heating method, a resistance heating method, or a lamp heating method.

  Thus, by using a cooling mechanism and a heating mechanism in combination with the base plate, the stability of the plate-like semiconductor is significantly increased.

  Along with the temperature control of the base plate, temperature control of the raw material melt is important. If the temperature of the melt is set near the melting point, the melt surface may be higher than the melting point because the molten metal surface of the raw material melt may solidify due to the base plate coming into contact with the melt. Is preferred. This can be strictly controlled using a plurality of thermocouples or a radiation thermometer.

  To strictly control the melt temperature, it is preferable to immerse the thermocouple in the melt directly. However, impurities from the thermocouple protection tube etc. may be mixed into the melt. It is necessary to make the structure prevent. The control method is preferably such that the temperature can be controlled indirectly by inserting a thermocouple into a crucible or the like, or the temperature of the silicon melt can be measured with a radiation thermometer.

  The crucible 111 containing the melt is installed on the heat insulating material 115 via the crucible base 114. This is used to keep the melt temperature uniform and to suppress heat removal from the crucible bottom to a minimum. On the heat insulating material 115, a crucible base 114 is installed, a crucible lift base 116 is connected, and a lift mechanism is provided. This is because the plate-like semiconductor grows on the base plate C, so that the base plate C is always moved up and down so as to be immersed at the same depth from the molten metal surface of the raw material melt. The method of enabling immersion at the same depth from the hot water surface is not limited to this. A method of keeping the molten metal surface position constant, that is, a method of replenishing the raw material taken out as a plate-like semiconductor is also applicable. For this, it is possible to use a method of melting raw material polycrystals (lumps), charging them sequentially in the melt, or sequentially charging powders. However, it is preferable not to disturb the melt surface as much as possible. If the melt surface is disturbed, the wave shape generated at that time is reflected on the melt surface side of the obtained plate semiconductor, which may impair the uniformity of the resulting plate semiconductor and impair quality stability. Because there is.

Next, another plate-like semiconductor manufacturing apparatus will be described with reference to FIG.
In FIG. 10, there is a fixed base 128 having an opening 133 of the heat shielding plate 132 on the crucible 121 attached to the crucible lifting table 126 and the crucible holding parts 124, 125, and capable of moving the opening 133. A base plate C for semiconductor manufacturing is connected to a fixed leg 127, and the fixed leg 127 is connected to a cooler 129. Further, the cooler 129 is connected to an arm 131 having a joint portion 130 whose angle can be changed. However, this figure does not show an apparatus such as a means for moving an arm or a joint or a chamber that can be evacuated. In this apparatus, a heat shielding plate 132 is opened on the crucible 121, and the base plate C is configured to draw an arbitrary trajectory. Crystals grow on the base plate C, and a plate-like semiconductor S is formed. At this time, it is possible to control the thickness of the formed plate-like semiconductor by controlling the temperature of the base plate C, the temperature of the semiconductor melt 123, and the like. In this apparatus, the arm 131 has the joint portion 130 so that the base plate C moves. However, the arm 131 may move together. Thus, by providing a mechanism for moving the entire arm, the substrate C can be immersed at the same depth from the molten metal surface of the semiconductor melt.

<Manufacturing method of plate semiconductor>
A method for manufacturing a plate-like semiconductor when the base plate of the present invention is used in the plate-like semiconductor manufacturing apparatus shown in FIG. 9 will be described. In particular, here, a case where silicon is used as a raw material will be described.

  First, a high-purity graphite crucible 111 is filled with a silicon lump (raw material) whose boron concentration is adjusted so that the specific resistance of the obtained plate-like silicon is 0.5 to 5 Ω · cm. The crucible is installed in an apparatus as shown in FIG. Next, the inside of the chamber is evacuated to reduce the inside of the chamber to a predetermined pressure. Thereafter, Ar gas is introduced into the chamber, and Ar gas is kept flowing from the upper part of the chamber at a flow rate of 10 L / min. The reason why the gas is constantly flowed in this way is to obtain a clean silicon surface.

  Next, the temperature of the silicon melting heater 112 is set to 1500 ° C., and the silicon lump in the crucible 111 is completely melted. At this time, since the silicon raw material melts and the liquid level becomes low, silicon powder is newly added so that the molten metal surface of the silicon melt is positioned 1 cm below the upper surface of the crucible 111. The silicon melting heater is preferably heated to about 1300 ° C. at a rate of 5 to 50 ° C./min, and then raised to a predetermined temperature, instead of raising the temperature to 1500 ° C. at a time. This is because when the temperature is rapidly increased, thermal stress is concentrated on the corners of the crucible, leading to breakage of the crucible.

  Thereafter, after confirming that the silicon is completely melted, the heater temperature is set to 1425 ° C. and held for 30 minutes to stabilize the melt temperature. Next, the crucible 111 is moved to a predetermined position using the crucible lifting table 116. The heater temperature at this time is preferably 1400 ° C. or higher and 1500 ° C. or lower. This is because, since the melting point of silicon is around 1410 ° C., when the temperature is set to 1400 ° C. or lower, the molten metal surface gradually hardens from the crucible wall. On the other hand, when the temperature is set to 1500 ° C. or higher, the growth rate of the obtained plate-like silicon is slow, and the productivity is deteriorated.

  Next, the silicon plate is grown, and the base plate as shown in FIG. 3 is advanced from the left side to the right side in FIG. At this time, the surface of the base plate, for example, the main surface S3 side, which is the growth surface in FIG. 3, is brought into contact with the silicon melt, and the base plate is moved so that the front portion F3 of the base plate is on the traveling direction side. In this way, the surface of the base plate is in contact with the silicon melt, so that the plate-like silicon is formed on the main surface S3 side. The trajectory for growing the plate-like silicon on the base plate is not particularly limited. For example, it is preferable to have a structure that can realize an arbitrary trajectory such as a circular trajectory, an elliptical trajectory, or a combination trajectory thereof.

  In FIG. 3, the shape of the traveling direction portion F of the base plate C is not particularly limited, but it is preferable that the silicon plate grown on the main surface S3 does not fall.

  The surface temperature of the base plate C when entering the silicon melt needs to be equal to or lower than the freezing point of the silicon melt. More preferably, it is 1100 degrees C or less. This is not preferable when the temperature of the base plate C is 1100 ° C. or higher because the growth rate of the plate-like silicon is slowed and the productivity is deteriorated. Since the base plate C has both a cooling mechanism and a heating mechanism, the temperature can be adjusted, so that not only the productivity is improved, but also the yield of the product is improved, and further, the quality can be stabilized. .

  In addition, as a method for controlling the surface temperature of the base plate C with good reproducibility, the base plate is attached to the fixed base at a position where the radiant heat from the silicon melt does not reach or has little influence, and immediately thereafter. By adopting a method of entering the silicon melt, an apparatus configuration that does not control the temperature of the base plate is possible.

  Here, although the manufacturing method of plate-like silicon has been described, as described above, by appropriately changing the material and shape of the base plate used for growth, metal, group IV (group IV-IV) ) It can be easily used for the production of plate-like semiconductors such as semiconductors, III-V semiconductors and II-VI semiconductors.

  Further, here, since the explanation is made using the manufacturing apparatus shown in FIG. 9, the plate-like silicon grows under the base plate C. However, it is also possible to produce plate-like silicon on the upper side of the base plate C by turning the base plate upside down with an apparatus configuration different from that in FIG.

  Next, the plate-shaped semiconductor manufacturing method according to the present invention will be described using the plate-shaped semiconductor manufacturing apparatus shown in FIG. Here, an example of a method for producing a plate-like semiconductor using the plate-like semiconductor production apparatus of FIG. 10 is shown, but the present invention is characterized in that the substrate is brought into contact with the melt regardless of the production apparatus. Further, the present invention is not limited to the material of the substrate and the material of the crucible.

  A silicon raw material in which the boron concentration is adjusted so that the specific resistance of the obtained silicon plate is 1 Ω · cm is filled in a quartz crucible 121 protected by a high-purity carbon crucible, and an apparatus as shown in FIG. Install in. Thereafter, exhaust is performed using a rotary pump until the pressure in the main chamber becomes 300 Pa, and then further exhaust is performed using a mechanical booster pump until 6 Pa.

  Next, the temperature of the crucible is raised to 500 ° C. at a rate of 4 ° C./min using an inverter with a frequency of 4 kHz and an electric power of 80 kW in the heater 122 for heating the crucible. Moisture contained in the carbon crucible is removed by holding for 90 minutes while maintaining the pressure in the main chamber at 6 Pa and the crucible temperature at 500 ° C. Also, the purpose of not raising the temperature at once is to prevent the crucible from being damaged due to thermal stress concentrated on the corners of the crucible.

  After such baking, the output of the inverter is once stopped and the heating of the crucible is stopped. In this state, Ar gas is filled until the pressure in the main body chamber reaches 800 hPa. When the inside of the main body chamber reaches 800 hPa, the crucible is heated again at a temperature increase rate of 10 ° C./min, and the temperature is increased until the crucible temperature reaches 1550 ° C. By stabilizing the crucible temperature at 1550 ° C., the silicon lump in the crucible eventually melts and becomes a silicon melt. After confirming that the silicon lump is completely dissolved, additional silicon lump or silicon powder is added so that the height of the silicon melt surface is 15 mm below the upper end of the crucible. After confirming that all of the added silicon lump has been melted, the set temperature of the crucible is lowered to 1425 ° C., and this state is maintained for 30 minutes to stabilize the temperature of the silicon melt.

  Next, the plate-like silicon is grown on the base plate C, and the growth surface of the base plate is moved so as to contact the silicon melt. Thus, the plate-like silicon S grows on the surface of the base plate when the growth surface of the base plate contacts the silicon melt. The orbit for producing the plate-like silicon S on the base plate C may be a circular or elliptical orbit. In particular, the yield of the obtained plate-like silicon S can be improved by adopting the device structure as shown in FIG. 10 that can realize an arbitrary trajectory.

  As shown in FIG. 10, the base plate C and the silicon plate S may be peeled off in the chamber or may be carried out of the chamber. In particular, if the production rate is to be increased, it is preferable to peel off the base plate C in the chamber and carry out only the silicon plate S outside the chamber. By doing so, not only the base plate C is not carried out of the chamber, but also the consumption of Ar gas can be greatly reduced, and cheaper plate-like silicon can be provided. It becomes.

<Solar cell manufacturing method>
For example, as shown in FIG. 4 (A), the produced plate-like semiconductor has a plate-like semiconductor that grows on a slit portion and a side portion in front of the immersion direction that is continuous with the main surface of the plate-like semiconductor. When used for battery cells, conventional solar cell manufacturing processes cannot be applied. Therefore, it is necessary to cut the manufactured plate semiconductor into wafers.

  FIG. 11 is a view in which the slit portion of the plate-like semiconductor is cut. At this time, cutting can be performed in a short time by using a laser. Moreover, since a solar cell characteristic will fall when the slit part which does not contribute to electric power generation is included, a high output can be obtained within the same area by cut | disconnecting.

  Hereafter, the process of producing a photovoltaic cell using the wafer obtained by cutting off the slit part of a plate-shaped semiconductor is demonstrated using FIG.

  (A) The wafer 30 obtained by cutting off the slit portion of the plate-like semiconductor is cleaned using an alkaline etching solution such as an aqueous sodium hydroxide solution.

  (B) An n-type impurity containing a phosphorus (P) -based compound is applied to the surface of the wafer 30 serving as a light receiving surface, and the n-type diffusion layer 32 is formed by thermal diffusion.

  (C) A SiN film is formed on the light receiving surface of the wafer 30 as a reflection preventing film 33 by a plasma CVD method.

  (D) An aluminum paste is printed on the back surface of the wafer 30 by a screen printing method, dried, baked, and aluminum as an impurity is diffused to form a BSF layer (not shown) made of a P + layer. An opening 34a for forming the back collector electrode 36 is formed in advance.

  (E) A silver paste is printed on the surface of the wafer 30 by a screen printing method to form the light receiving surface electrode 35.

  (F) A silver paste is printed on the opening 34 (a) of the back surface collecting electrode 34 by a screen printing method, dried, and then fired to form a back surface wiring electrode 36.

  (G) Solder dipping is performed, and the surface electrodes of the light receiving surface electrode 35 and the back surface wiring electrode 36 are covered with the solder layer 37 to complete the solar battery cell 40.

  The wafer obtained by cutting the plate-like semiconductor of the present invention is reduced in warpage by forming a slit portion, so that the number of wafers that can be cleaned at one time in batch processing is less than that without a slit portion. Increases productivity, such as In addition, handling of the wafer becomes easy and productivity is improved.

<Examples 1-3, Comparative Example 1>
(Production of silicon plate)
A silicon raw material whose boron concentration was adjusted so that the specific resistance was 2 Ω · cm was placed in a quartz crucible protected by a high-purity carbon crucible and fixed in an apparatus as shown in FIG.

First, the inside of the chamber was evacuated to about 10 ⁻⁵ torr and replaced with Ar gas to normal pressure, and then Ar gas was allowed to flow at 10 L / min. Next, the silicon raw material is melted by a heater. The temperature of the silicon melting heater is increased to 1500 ° C. at a temperature increase rate of 10 ° C./min, and after confirming that the silicon raw material is completely dissolved, the crucible temperature is set to 1425. The temperature was maintained at 0 ° C. for stabilization. The temperature of the main surface S3, which is the growth surface of the base plate in FIG. 3, was controlled to 200 ° C., and the growth surface was immersed so as to pass a portion 8 mm below the molten metal surface, thereby growing plate-like silicon.

  The growth surface of the base plate used was 180 mm in length, 160 mm in width, and the thickness of the base plate was 30 mm. The lengths of the grooves were set to 10 mm, 20 mm, and 30 mm, respectively. The width W3 of the groove was 3 mm, and the depth D3 was 10 mm. The number of grooves was set to be 5 and equally spaced. The case where the base plate of FIG. 8 was used and a base plate without a groove was used as Comparative Example 1.

  Next, in the grown plate-like silicon, the undivided portion of the portion grown from the growth surface of the base plate was cut into a 140 mm square with a laser, and the amount of warpage of the unbroken plate-like silicon after cutting was measured. .

Then, the solar cell was produced through the process of the solar cell. In order to clean the obtained plate-like silicon, alkali etching with sodium hydroxide was performed, and then an n ⁺ layer was formed on the p-type base plate by POCl ₃ diffusion. After removing the PSG film formed on the plate-like silicon surface with hydrofluoric acid, a silicon nitride film was formed on the n ⁺ layer on the light-receiving surface side of the solar cell using plasma CVD. Next, the n ⁺ layer formed on the back surface side of the solar cell is etched away with a mixed solution of nitric acid and hydrofluoric acid to expose the p base plate, and the back electrode and p ⁺ layer are formed thereon. Formed simultaneously. Next, an electrode on the light receiving surface side was formed by using a screen printing method. Thereafter, solder dipping was performed to produce a solar cell. Under irradiation of AM 1.5 and 100 mW / cm ² , the solar cell was evaluated according to “Crystalline Solar Cell Output Measurement Method (JIS C 8913 (1988))”.

  Table 1 shows the results when immersed 100 times in each condition. Here, the number of 140 mm square plate-like silicon is the number of sheets excluding the plate silicon that could not secure a 140 mm square size due to cracking. As can be seen from the table, by inserting the groove of the present invention, there are few cracks, and it can be seen that there are many sheets that can secure a 140 mm square size when taken out of the chamber. Moreover, it turns out that this effect is so large that the length of a groove | channel is long. It can also be seen that the amount of warpage is reduced by inserting the groove of the present invention in warping after cutting into 140 mm square. The silicon plate manufacturing process with a small amount of warpage was easy.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the base plate for semiconductor manufacture of this invention. It is a figure which shows the plate-shaped semiconductor produced using the base plate for semiconductor manufacture of FIG. It is a figure which shows the base plate for semiconductor manufacture of this invention. It is a figure which shows the plate-shaped semiconductor produced using the base plate for semiconductor manufacture of FIG. It is a figure which shows the base plate for semiconductor manufacture of this invention. It is a figure which shows the base plate for semiconductor manufacture of this invention. It is a figure which shows the conventional base plate for semiconductor manufacture. It is a figure which shows the plate-shaped semiconductor produced using the base plate for semiconductor manufacture of FIG. It is a schematic sectional drawing which shows an example of the manufacturing apparatus for manufacturing the plate-shaped semiconductor of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus for manufacturing the plate-shaped semiconductor of this invention. It is a schematic diagram which shows the manufacturing process of the photovoltaic cell of this invention. It is a schematic diagram which shows the manufacturing process of the photovoltaic cell of this invention.

Explanation of symbols

  30 Wafer, 32 n-type diffusion layer, 33 Antireflection film, 34 Back surface collecting electrode, 35 Light receiving surface electrode, 36 Back surface wiring electrode, 37 Solder layer, 40 Solar cell, 111, 121 Crucible, 112, 122 Heater, 113 Raw material melt, 114 crucible base, 115 heat insulating material, 116, 126 crucible lifting base, 117 shaft, 118, 128 fixing base, 123 semiconductor melt, 124, 125 crucible holding part, 127 fixing leg, 129 cooler, 130 Joint part, 131 arm, 132 heat shielding plate, 133 opening, F1, F3 side surface in front of immersion direction of base plate for semiconductor manufacturing, S2, S4, S8 main surface of plate semiconductor, S1, S3, S7 semiconductor manufacturing Main surface of base plate for substrate, width of W1, W3 groove, depth of D1, D3 groove, groove separating V3, V7 and main surface, C base plate for semiconductor manufacturing S plate-like semiconductor.

Claims (4)

A base plate having a crystal growth surface is immersed in the semiconductor melt, Oite method of manufacturing a semiconductor of growing semiconductor on said base plate,
The base plate has a groove in which the crystal growth surface extends from the front part to the rear part in the immersion direction.
Semiconductor manufacturing method. The method for manufacturing a semiconductor according to claim 1, wherein the groove is substantially parallel to a dipping direction. The semiconductor manufacturing method according to claim 1, wherein there are two or more grooves. A semiconductor manufacturing apparatus comprising a crucible containing a semiconductor melt and a base plate having a crystal growth surface,
The base plate is immersed in the semiconductor melt to grow a semiconductor on the base plate,
The base plate has a groove in which the crystal growth surface extends from the front part to the rear part in the immersion direction.
Semiconductor manufacturing equipment.

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