JP5030102B2

JP5030102B2 - Sheet manufacturing method and sheet manufacturing substrate

Info

Publication number: JP5030102B2
Application number: JP2007275088A
Authority: JP
Inventors: 浩司吉田
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2007-10-23
Filing date: 2007-10-23
Publication date: 2012-09-19
Anticipated expiration: 2027-10-23
Also published as: JP2009102193A

Description

本発明は、シート製造方法およびシート製造用基板に関する。詳しくは、シート厚さの分布を低減するシート製造方法に関する。 The present invention relates to a sheet manufacturing method and a sheet for manufacturing board. Specifically, the present invention relates to a sheet manufacturing method that reduces the distribution of sheet thickness.

従来のシリコンシート製造方法の１つとして、たとえば、特開２００１−２２３１７２号公報に開示される「シート製造方法、シート、シート製造装置および太陽電池」が挙げられる。 As one of conventional silicon sheet manufacturing methods, for example, “sheet manufacturing method, sheet, sheet manufacturing apparatus, and solar cell” disclosed in Japanese Patent Laid-Open No. 2001-223172 can be cited.

この製造方法によれば、原料の融液に冷却された凹凸構造を持つ基板を浸漬し、その基板表面上に板状シリコンシートを成長させるというものである。このときこの基板の凹部深さ、言い換えれば溝深さを面内で変更することにより、基板面内の冷却度合いを制御することにより、浸漬前の基板面内温度分布を制御し、作製された板状シリコンシートの厚さの分布を制御しようとするものである。 According to this manufacturing method, a cooled substrate having a concavo-convex structure is immersed in a raw material melt, and a plate-like silicon sheet is grown on the substrate surface. At this time, it was produced by controlling the temperature distribution in the substrate surface before immersion by controlling the degree of cooling in the substrate surface by changing the recess depth of the substrate, in other words, the groove depth in the surface. It is intended to control the thickness distribution of the plate-like silicon sheet.

また、特開２００２−９４０９８号公報に開示される「結晶薄板の製造方法および結晶薄板を用いた太陽電池」によれば、熱伝導率の異なる多層基体材料を用いることにより、基体表面温度を制御し、材料融液に基体を浸漬させたときの、基体表面に作製された薄板の厚さを制御しようというものである。
特開２００１−２２３１７２号公報特開２００２−９４０９８号公報 In addition, according to “Crystal Thin Plate Manufacturing Method and Solar Cell Using Crystal Thin Plate” disclosed in Japanese Patent Application Laid-Open No. 2002-94098, the substrate surface temperature is controlled by using multilayer base materials having different thermal conductivities. Then, when the substrate is immersed in the material melt, the thickness of the thin plate formed on the substrate surface is to be controlled.
JP 2001-223172 A JP 2002-94098 A

しかし、上記特許文献１および特許文献２に記載されているシートの厚さの分布の低減の方策は、何れも、基板を材料融液に浸漬する前に冷却し、基板溝部の形状、若しくは熱伝導率の異なる多層基体材料を用いることにより、浸漬前基板面内温度分布を制御し、結果的に作製されるシリコンシートの厚さの分布を低減しようとするものである。このような手段を用いてもシリコンシートの厚さの分布の低減は可能であるが、生産性という観点から鑑みると、シリコンシートの厚さの分布を低減するために、基板の冷却手段を必要とすることによる装置設備費およびランニングコストの上昇という課題がある。また、基板を冷却した場合、所望の基板面内の温度分布に達するまで、一定の所要時間を要することによる、生産性が低下し太陽電池のコストが上昇するといった課題がある。 However, all of the measures for reducing the thickness distribution of the sheet described in Patent Document 1 and Patent Document 2 described above are to cool the substrate before immersing it in the material melt, and to form the shape of the substrate groove or heat. By using multi-layer substrate materials having different conductivities, it is intended to control the temperature distribution in the substrate surface before immersion and to reduce the thickness distribution of the resulting silicon sheet. Although it is possible to reduce the thickness distribution of the silicon sheet using such means, from the viewpoint of productivity, a cooling means for the substrate is necessary to reduce the thickness distribution of the silicon sheet. There is a problem of an increase in equipment cost and running cost. Further, when the substrate is cooled, there is a problem that productivity is lowered and the cost of the solar cell is increased due to a certain time required until the temperature distribution in the desired substrate surface is reached.

また、基板の主面内の熱抵抗値の分布を制御することなく基板を融液に浸漬した場合、最初に浸漬される前端側の基板温度に比べて、基板温度よりも温度の高い融液からの熱伝導により、基板中央部または後端側の基板温度が高くなる。ここで、シートを構成する結晶の成長速度は、融液から基板への熱移動量に依存することが知られている。すなわち、基板温度が低い程、融液との温度差が大きくなる。かかる温度差が大きいと熱移動量も大きくなり、シートを構成する結晶の成長速度も大きくなる。同様に基板温度が高い程、融液との温度差が小さくなる。かかる温度差が小さいと熱移動量も小さくなり、シートを構成する結晶の成長速度も小さくなる。 In addition, when the substrate is immersed in the melt without controlling the distribution of the thermal resistance value in the main surface of the substrate, the melt having a temperature higher than the substrate temperature compared to the substrate temperature on the front end side to be immersed first. Due to heat conduction from the substrate, the substrate temperature at the center or rear end of the substrate increases. Here, it is known that the growth rate of the crystals constituting the sheet depends on the amount of heat transfer from the melt to the substrate. That is, the lower the substrate temperature, the greater the temperature difference from the melt. When this temperature difference is large, the amount of heat transfer increases, and the growth rate of the crystals constituting the sheet also increases. Similarly, the higher the substrate temperature, the smaller the temperature difference from the melt. When this temperature difference is small, the amount of heat transfer is also small, and the growth rate of the crystals constituting the sheet is also small.

上述の理由より、主面内の熱抵抗の分布が実質的に一様な基板を融液に浸漬させた場合、基板前端部上に成長したシートは、その基板中央部および基板後端部上に成長したシートに比べてより厚く成長する。このように主面内における厚さの分布の大きいシートから、太陽電池を作製するプロセスにおいて、電極の印刷をはじめ、さまざまな不良の原因となり、歩留りを低下させるという課題がある。 For the reasons described above, when a substrate having a substantially uniform distribution of thermal resistance in the main surface is immersed in the melt, the sheet grown on the front end of the substrate is on the center and back of the substrate. It grows thicker than a sheet that has grown. Thus, in the process of manufacturing a solar cell from a sheet having a large thickness distribution in the main surface, there is a problem of causing various defects including electrode printing and reducing the yield.

本発明は、金属材料および半導体材料のうち少なくともいずれかを一方を含有材料の融液から直接基板の主面上に作製されるシートの厚さの分布を低減することを目的とする。 An object of the present invention is to reduce the thickness distribution of a sheet produced directly on the main surface of a substrate from a melt of a material containing at least one of a metal material and a semiconductor material.

本発明は、一方の主面に複数の凸部を有する基板の主面を金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、この材料の固相を主面上で凸部を起点として成長させることにより、材料を主成分とするシートを得るシート製造方法であって、基板の融液への浸漬方向における基板前部の凸部の熱抵抗値が基板の浸漬方向における基板後部の凸部の熱抵抗値に比べて大きいことを特徴とするシート製造方法である。 In the present invention, a main surface of a substrate having a plurality of convex portions on one main surface is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and the solid phase of this material is A sheet manufacturing method for obtaining a sheet containing a material as a main component by growing a convex portion as a starting point, wherein the thermal resistance value of the convex portion at the front portion of the substrate in the direction of immersion in the melt of the substrate is It is a sheet manufacturing method characterized by being large compared with the thermal resistance value of the convex part of the substrate rear part in the dipping direction .

本発明にかかるシート製造方法において、基板の融液への浸漬方向において、基板前端部から基板中央部へ向かって凸部の熱抵抗値を徐々に小さくすることができる。 The sheet manufacturing method according to the present invention, in the immersion direction to melt the board, it is possible to gradually reduce the thermal resistance of the convex portion toward the substrate front end to the center of the substrate.

また、本発明にかかるシート製造方法において、凸部の熱抵抗値を変えることは、凸部の構成材料の熱伝導率または凸部の断面積を変えることにより行うことができる。また、基板の融液への浸漬方向において、基板前部の凸部の構成材料の熱伝導率を基板後部の凸部の構成材料の熱伝導率に比べて小さくすることができる。 In the sheet manufacturing method according to the present invention, the thermal resistance value of the convex portion can be changed by changing the thermal conductivity of the constituent material of the convex portion or the sectional area of the convex portion. Further, in the direction of immersion of the substrate in the melt, the thermal conductivity of the constituent material of the convex portion at the front portion of the substrate can be made smaller than the thermal conductivity of the constituent material of the convex portion at the rear portion of the substrate .

また、本発明は、一方の主面に複数の凸部を有し、主面を金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、主面上にこの材料を主成分とするシートを製造するためのシート製造用基板であって、基板の融液への浸漬方向における基板前部の凸部の熱抵抗値が基板の浸漬方向における基板後部の凸部の熱抵抗値に比べて大きいことを特徴とするシート製造用基板である。 Further, the present invention has a plurality of convex portions on one main surface, the main surface is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and this material is formed on the main surface. A sheet manufacturing substrate for manufacturing a sheet having a main component as a main component, wherein the thermal resistance value of the convex portion of the front portion of the substrate in the immersion direction of the substrate in the melt is the value of the convex portion of the rear portion of the substrate in the immersion direction of the substrate. The sheet manufacturing substrate is characterized by being larger than a thermal resistance value.

本発明によれば、金属材料および半導体材料のうち少なくともいずれかを一方を含有材料の融液から直接基板の主面上に作製されるシートの厚さの分布を低減することができる。かかるシートの厚さの分布が低減されることにより、必要最低の厚さに合わせてシート全体の厚さの分布を低減することが可能となる。また、シート全体の平均厚さを低減することにより、低コストで太陽電池を提供することが可能となる。 According to the present invention, it is possible to reduce the thickness distribution of a sheet produced directly on the main surface of a substrate from a melt of a material containing at least one of a metal material and a semiconductor material. By reducing the thickness distribution of the sheet, the thickness distribution of the entire sheet can be reduced in accordance with the minimum necessary thickness. Moreover, it becomes possible to provide a solar cell at low cost by reducing the average thickness of the whole sheet.

本発明にかかるシート製造方法は、図１〜図１２を参照して、一方の主面１００ｍに複数の凸部１００ｐを有する基板１００の主面１００ｍを金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液３０６に接触させ、材料の固相を主面１００ｍ上で凸部を起点として成長させることにより、前記材料を主成分とするシートを得るシート製造方法であって、基板１００の一部分の凸部１０１ｐ，１０２ｐ，１０６ｐの熱抵抗値が基板の他の部分の凸部１０４ｐ，１０７ｐ，１１４ｐ，１１７ｐの熱抵抗値に比べて大きいことを特徴とする。本発明は、基板の凸部１００ｐのうち一部分の凸部１０１ｐ，１０２ｐ，１０６ｐの熱抵抗値を他の部分の凸部１０４ｐ，１０７ｐ，１１４ｐ，１１７ｐの熱抵抗値に比べて大きくすることにより、基板１００の主面１００ｍ上に形成されるシートの厚さの分布を低減するものである。 In the sheet manufacturing method according to the present invention, referring to FIGS. 1 to 12, at least one of a metal material and a semiconductor material is used as a main surface 100 m of a substrate 100 having a plurality of convex portions 100 p on one main surface 100 m. A sheet manufacturing method for obtaining a sheet containing the material as a main component by bringing the solid phase of the material into contact with the melt 306 containing the material and growing the solid phase of the material on the main surface 100 m starting from the convex portion. The thermal resistance values of the convex portions 101p, 102p, and 106p in a portion of 100 are larger than the thermal resistance values of the convex portions 104p, 107p, 114p, and 117p in other portions of the substrate. The present invention increases the thermal resistance values of some of the convex portions 101p, 102p, and 106p of the convex portion 100p of the substrate as compared with the thermal resistance values of the convex portions 104p, 107p, 114p, and 117p of the other portions, The thickness distribution of the sheet formed on the main surface 100m of the substrate 100 is reduced.

上記一部分および他の部分がどの部分とするかは、基板のどの方向についてその基板上に形成されるシートの厚さの分布を低減するかによって異なり、特に制限はない。図１〜図４、図８および図９を参照して、基板１００の融液への浸漬方向Ｄにおけるシートの厚さの分布を低減するためには、一部分は基板の融液への浸漬方向における基板前部１０１，１０２であり、他の部分は浸漬方向における基板後部１０４，１１４であることが好ましい。また、図５〜図７、図１０および図１１を参照して、一部分は基板１００の融液への浸漬方向Ｄと垂直な方向における基板中部１０６であり、他の部分は垂直な方向における基板側部１０７，１１７であることが好ましい。以下、より具体的に説明する。 Which part is used as the part and the other part depends on which direction of the substrate the thickness distribution of the sheet formed on the substrate is reduced, and is not particularly limited. 1-4, FIG. 8, and FIG. 9, in order to reduce the thickness distribution of the sheet in the immersion direction D of the substrate 100 in the melt, a part of the substrate 100 is immersed in the melt. It is preferable that the substrate front portions 101 and 102 in FIG. 4 and the other portions are the substrate rear portions 104 and 114 in the immersion direction. 5 to 7, 10, and 11, a part is a substrate middle portion 106 in a direction perpendicular to the direction D of immersion in the melt of the substrate 100, and the other part is a substrate in the vertical direction. The side portions 107 and 117 are preferable. More specific description will be given below.

（実施形態１）
本発明にかかるシート製造方法の一実施形態は、図１〜図４を参照して、一方の主面１００ｍに複数の凸部１００ｐを有する基板１００の主面１００ｍを金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、材料の固相を主面上で凸部１００ｐを起点として成長させることにより、材料を主成分とするシートを得るシート製造方法であって、基板１００の融液への浸漬方向Ｄにおいて基板前部１０１（領域Ｆ）の凸部１０１ｐの熱抵抗値が基板後部１０４（領域Ｂ）の凸部１０４ｐの熱抵抗値に比べて大きいことを特徴とする。ここで、熱抵抗値とは熱抵抗の値をいい、熱抵抗とは単位時間当たりの発熱量当たりの温度上昇量をいい、単位は℃・Ｗ^-1である。 (Embodiment 1)
In one embodiment of the sheet manufacturing method according to the present invention, referring to FIGS. 1 to 4, a main surface 100 m of a substrate 100 having a plurality of convex portions 100 p on one main surface 100 m is made of a metal material and a semiconductor material. A sheet manufacturing method for obtaining a sheet containing a material as a main component by bringing the material into contact with a melt of a material containing at least one and growing a solid phase of the material on the main surface starting from the convex portion 100p. In the immersion direction D of the substrate 100 in the melt, the thermal resistance value of the convex portion 101p of the substrate front portion 101 (region F) is larger than the thermal resistance value of the convex portion 104p of the substrate rear portion 104 (region B). Features. Here, the thermal resistance value refers to the value of thermal resistance, and the thermal resistance refers to the amount of temperature rise per unit amount of heat generation, and the unit is ° C. · W ⁻¹ .

本実施形態のシート製造方法においては、たとえば図１を参照して、基板１００は、その一方の主面１００ｍに複数の凸部１００ｐを有し、その主面１００ｍを上記材料の融液に浸漬することにより、その材料の固相をその主面１００ｍ上で、各凸部１００ｐを起点として成長させて、その材料を主成分とするシートが得られる。ここで、基板１００の主面１００ｍに凸部１００ｐが無く単なる平面である場合、シートの結晶成長の核となる部分が非常に少なく、その結果、結晶サイズの大きなデンドライト結晶の成長が支配的なシートが形成される場合がある。かかるデンドライト結晶は、結晶の成長方向によって成長速度が大きく異なる。たとえば、シリコン結晶の成長速度は、（１１０）面に垂直な方向（［１１０］方向）については非常に高く、また（１１２）面に垂直な方向（［１１２］方向）については非常に低い。この様な成長であるため、作製されたシート面内でデンドライト結晶の（１１２）面同士の成長が重ならず、局所的に穴の開いたシートが形成されてしまい、通常の製品として使用するためには不都合となる。 In the sheet manufacturing method of the present embodiment, for example, referring to FIG. 1, a substrate 100 has a plurality of convex portions 100p on one main surface 100m, and the main surface 100m is immersed in a melt of the above material. By doing so, the solid phase of the material is grown on the main surface 100m from each convex portion 100p as a starting point, and a sheet containing the material as a main component is obtained. Here, when the main surface 100m of the substrate 100 is not a convex surface 100p and is a mere plane, there are very few core portions for crystal growth of the sheet, and as a result, the growth of dendritic crystals having a large crystal size is dominant. A sheet may be formed. Such dendrite crystals have greatly different growth rates depending on the crystal growth direction. For example, the growth rate of a silicon crystal is very high in the direction perpendicular to the (110) plane ([110] direction) and very low in the direction perpendicular to the (112) plane ([112] direction). Because of this growth, the growth of the (112) planes of the dendrite crystals does not overlap within the produced sheet surface, and a sheet with holes is locally formed, which is used as a normal product. This is inconvenient.

そこで、本実施形態に示されるように、基板の主面にシートの結晶成長の起点となる凸部１００ｐを設けることにより、結晶成長核の制御されたシートを形成することが可能となる。 Therefore, as shown in the present embodiment, by providing the main surface of the substrate with a convex portion 100p serving as a starting point for crystal growth of the sheet, a sheet with controlled crystal growth nuclei can be formed.

ここで、シートの原料となる材料（以下、シート材料ともいう）の融液からシートを形成するためには、基板１００の主面１００ｍの凸部１００ｐと接する融液部分を融点以下にする必要がある。具体的には、基板の主面の凸部１００ｐが高温の融液と接することにより、融液の熱が凸部１００ｐを通じて基板１００側に流れ、融点以下となることにより、基板表面の各凸部１００ｐの先端近傍が成長の起点となって複数の結晶が成長し、それらの結晶が繋がってシートが形成されることとなる。結晶の成長速度、すなわちシートの厚さは、主に融液の過冷却度に関係し、過冷却度が大きい程結晶の成長速度も大きいと推測される。ここで、過冷却度とは、液体が凝固点（すなわち、転移点）を過ぎて冷却されても固体化せず、液体の状態を保持する現象において、その液体の温度と凝固点との温度差をいう。 Here, in order to form a sheet from a melt of a material that is a raw material of the sheet (hereinafter also referred to as a sheet material), it is necessary to make the melt portion in contact with the convex portion 100p of the main surface 100m of the substrate 100 below the melting point. There is. Specifically, when the convex portion 100p on the main surface of the substrate is in contact with the high-temperature melt, the heat of the melt flows to the substrate 100 side through the convex portion 100p and becomes below the melting point, thereby causing each convexity on the substrate surface. A plurality of crystals grow from the vicinity of the tip of the portion 100p as a starting point of growth, and the crystals are connected to form a sheet. The crystal growth rate, that is, the sheet thickness, is mainly related to the degree of supercooling of the melt, and it is assumed that the crystal growth rate increases as the degree of supercooling increases. Here, the degree of supercooling refers to the temperature difference between the temperature of the liquid and the freezing point in a phenomenon in which the liquid does not solidify even if it is cooled past the freezing point (that is, the transition point) and maintains the liquid state. Say.

従来の基板のように、基板１００の全ての凸部１００ｐの熱抵抗値が実質的に等しい場合、基板前端部１０１ｅをシート材料の融液に浸漬したとき、その基板前端部１０１ｅは融液からの熱を受けて昇温し、次に、基板内の熱伝導により、基板後端部１０４ｅへ熱が移動することとなる。その結果、融液に浸漬する瞬間の基板温度は、基板前端部１０１ｅほど高く、基板後端部１０４ｅほど低くなる。融液から基板１００への熱の移動量は、融液と基板との温度差が大きいほど大きくなるため、基板前端部１０１ｅ側に位置する基板前部１０１での凸部１０１ｐにおける熱の移動量は、基板後端部１０４ｅ側に位置する基板後部１０４での凸部１０４ｐにおける熱の移動量に比べて大きくなる。結果、基板の主面上に形成されるシートは、基板前端部ほど厚く、基板後端部ほど板厚分布が薄くなる。 When the thermal resistance values of all the convex portions 100p of the substrate 100 are substantially equal as in the conventional substrate, when the front end portion 101e of the substrate is immersed in the melt of the sheet material, the front end portion 101e of the substrate is removed from the melt. Then, the temperature rises, and then heat is transferred to the rear end 104e of the substrate due to heat conduction in the substrate. As a result, the substrate temperature at the moment of immersion in the melt is higher at the substrate front end 101e and lower at the substrate rear end 104e. Since the amount of heat transfer from the melt to the substrate 100 increases as the temperature difference between the melt and the substrate increases, the amount of heat transfer in the convex portion 101p at the substrate front portion 101 located on the substrate front end portion 101e side. Is larger than the amount of heat transfer in the convex portion 104p at the substrate rear portion 104 located on the substrate rear end portion 104e side. As a result, the sheet formed on the main surface of the substrate is thicker at the front end portion of the substrate, and the plate thickness distribution is thinner at the rear end portion of the substrate.

そこで、本実施形態においては、図１および図２を参照して、基板前部１０１の凸部１０１ｐの裾部分を切削することにより、凸部１０１ｐの断面積を小さくすることが可能となる。かかる裾部分を切削した凸部（基板前部の凸部１０１ｐ）は裾部分を切削していない凸部（基板後部の凸部１０４ｐ）に比べて断面積が小さくなるため、熱容量も小さくなり、一定の伝熱量に対してより高温になる。高温となって融液との温度差が小さくなるほどその凸部の熱抵抗値は大きくなる。基板前部１０１の凸部１０１ｐの熱抵抗値を基板後部１０４の凸部１０４ｐの熱抵抗値に比べて大きくすることにより、基板前部１０１におけるシートの結晶成長を抑制することができ、基板前部１０１におけるシートの厚さを低減することができる。こうして、基板の主面上に形成されるシートの前部の厚さを低減することが可能となる。 Therefore, in the present embodiment, referring to FIG. 1 and FIG. 2, it is possible to reduce the cross-sectional area of the convex portion 101p by cutting the bottom portion of the convex portion 101p of the substrate front portion 101. Since the convex portion (the convex portion 101p at the front portion of the substrate) cut from the skirt portion has a smaller cross-sectional area than the convex portion (the convex portion 104p at the rear portion of the substrate) where the skirt portion is not cut, the heat capacity is also reduced. Higher temperature for a certain amount of heat transfer. The higher the temperature is, the smaller the temperature difference from the melt becomes, the greater the thermal resistance value of the convex portion. By making the thermal resistance value of the convex portion 101p of the substrate front portion 101 larger than the thermal resistance value of the convex portion 104p of the substrate rear portion 104, it is possible to suppress the crystal growth of the sheet in the substrate front portion 101, and The sheet thickness in the portion 101 can be reduced. Thus, the thickness of the front portion of the sheet formed on the main surface of the substrate can be reduced.

ここで、基板前部１０１の凸部１０１ｐの熱抵抗値を大きくする方法としては、特に制限はなく、図２に示すような凸部１０１ｐの裾部分を切削する方法の他、図３に示すような凸部１０１ｐの凸部形状そのものを鋭角化する方法がある。 Here, there is no restriction | limiting in particular as a method of enlarging the thermal resistance value of the convex part 101p of the board | substrate front part 101, It shows in FIG. 3 besides the method of cutting the skirt part of the convex part 101p as shown in FIG. There is a method of sharpening the convex shape of the convex portion 101p itself.

上記のように、図２および図３に示すような本実施形態の基板においては、基板前部１０１の一定部分が他の部分（基板後部１０４）に比べて凸部の熱抵抗値が大きい構造を有する。かかる構造を有する基板においては、基板前部の熱抵抗値の大きな凸部上で形成されたシートの厚さは、基板前部の熱抵抗値を制御していない基板の場合と比べて、シート前半部が薄くなっているため、シート全体の厚さ分布は低減している。しかし、厳密には基板前部１０１の熱抵抗値の大きな凸部１０１ｐ上で形成されたシートにおいても、基板前端部から基板中央部へかけシート厚さの分布の傾きが存在する。そこで、図４を参照して、基板１００の融液への浸漬方向において、基板前端部１０１ｅから基板中央部１０５ｃへ向かって凸部１０１ｐの熱抵抗値が徐々に小さくすることにより、基板前部１０１におけるシートの厚さ分布の傾きを抑制することができる。ここで、凸部１０１ｐの熱抵抗低値を徐々に変える方法は、特に制限はなく、図４に示すような凸部１０１ｐの凸部形状そのものを徐々に鋭角化する方法の他、凸部の裾部分の切削深さを徐々に変える方法（図示せず）がある。 As described above, in the substrate of this embodiment as shown in FIG. 2 and FIG. 3, the fixed portion of the substrate front portion 101 has a larger thermal resistance value of the convex portion than the other portion (substrate rear portion 104). Have In the substrate having such a structure, the thickness of the sheet formed on the convex portion having a large thermal resistance value at the front portion of the substrate is larger than that of the substrate in which the thermal resistance value at the front portion of the substrate is not controlled. Since the front half is thin, the thickness distribution of the entire sheet is reduced. However, strictly speaking, even in the sheet formed on the convex portion 101p having a large thermal resistance value of the substrate front portion 101, there is an inclination of the sheet thickness distribution from the substrate front end portion to the substrate center portion. Therefore, referring to FIG. 4, in the immersion direction of the substrate 100 in the melt, the thermal resistance value of the convex portion 101p gradually decreases from the substrate front end portion 101e toward the substrate center portion 105c, whereby the substrate front portion The inclination of the sheet thickness distribution at 101 can be suppressed. Here, the method of gradually changing the low thermal resistance value of the convex portion 101p is not particularly limited. In addition to the method of gradually sharpening the convex shape of the convex portion 101p as shown in FIG. There is a method (not shown) for gradually changing the cutting depth of the hem portion.

ここで、シートを形成するための材料は、シート形成が可能な金属材料および半導体材料のうち少なくともいずれか一方を含有するものあれば特に制限はなく、金属材料としてはチタン（Ｔｉ）、アルミニウム（Ａｌ）などが挙げられ、半導体材料としてはシリコン（Ｓｉ）、砒素化ガリウム（ＧａＡｓ）などが挙げられる。 Here, the material for forming the sheet is not particularly limited as long as it includes at least one of a metal material and a semiconductor material capable of forming a sheet. Examples of the metal material include titanium (Ti), aluminum ( Al) and the like, and examples of the semiconductor material include silicon (Si) and gallium arsenide (GaAs).

（実施形態２）
本発明にかかるシート製造方法の他の実施形態は、図５〜図７を参照して、一方の主面１００ｍに複数の凸部１００ｐを有する基板１００の主面１００ｍを金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、材料の固相を主面上で凸部１００ｐを起点として成長させることにより、材料を主成分とするシートを得るシート製造方法であって、基板１００の融液への浸漬方向Ｄと垂直な方向において基板中部１０６（領域Ｃ）の凸部１０６ｐの熱抵抗値が基板側部１０７（領域Ｓ）の凸部１０７ｐの熱抵抗値に比べて大きいことを特徴とする。なお、通常の場合、基板側部１０７は、基板中部１０６の両側に存在しており、両側の基板側部を意味する。 (Embodiment 2)
In another embodiment of the sheet manufacturing method according to the present invention, referring to FIGS. 5 to 7, the main surface 100 m of the substrate 100 having a plurality of convex portions 100 p on one main surface 100 m is made of a metal material and a semiconductor material. This is a sheet manufacturing method for obtaining a sheet containing a material as a main component by bringing it into contact with a melt of a material containing at least one of them and growing the solid phase of the material on the main surface starting from the convex portion 100p. Thus, the thermal resistance value of the convex portion 106p of the substrate middle portion 106 (region C) becomes the thermal resistance value of the convex portion 107p of the substrate side portion 107 (region S) in the direction perpendicular to the immersion direction D of the substrate 100 in the melt. It is characterized by being larger than that. In a normal case, the substrate side portion 107 exists on both sides of the substrate middle portion 106 and means the substrate side portions on both sides.

図１２を参照して、通常、坩堝３０１に保持されたシート材料の融液３０６は、坩堝３０１を通して加熱されるために、融液中央部３０６ｃに比べて坩堝３０１近傍の融液周辺部３０６ｒの融液温度は高くなる。坩堝サイズに比べて、融液３０６に浸漬してその主面上に結晶シートを形成する基板サイズが十分小さくないとき、言い換えれば、坩堝３０１の壁と基板側端１０７ｅとの距離が十分に取れない場合、従来の基板を用いると、基板側端１０７ｅ付近の基板側部１０７に形成されるシートは、基板中部１０６に形成されるシートに比べて結晶成長速度が遅くなる。すなわち基板中部１０６に形成されるシートの厚さに比べて、基板側部１０７で形成されるシートの厚さは薄くなる。 Referring to FIG. 12, the sheet material melt 306 held in the crucible 301 is usually heated through the crucible 301, so that the melt peripheral portion 306r near the crucible 301 is closer to the melt central portion 306c. The melt temperature increases. Compared to the crucible size, when the substrate size on which the crystal sheet is formed on the main surface by being immersed in the melt 306 is not sufficiently small, in other words, the distance between the wall of the crucible 301 and the substrate side end 107e is sufficiently large. If the conventional substrate is not used, the sheet formed on the substrate side portion 107 near the substrate side end 107e has a slower crystal growth rate than the sheet formed on the substrate middle portion 106. That is, the thickness of the sheet formed on the substrate side portion 107 is smaller than the thickness of the sheet formed on the substrate middle portion 106.

そこで、本発明では、図５および図６に示すように、基板側端部１０７ｅ付近に位置する基板側部１０７の凸部１０７ｐの断面積を基板中部１０６の凸部１０６ｐの断面積に比べて大きくすることにより、基板端部１０７の凸部１０７ｐの熱抵抗値に比べて基板中部１０６の凸部１０６ｐの熱抵抗値を大きくすることができる。この結果、基板端部および基板中部で同断面積の凸部を用いた従来の基板の主面上に形成されたシートに比べて、本実施形態の基板の主面上に形成されるシートは、基板端部上では比較的厚く、基板中央部上では比較的薄く形成される。すなわち、本実施形態の基板の主面上に形成されるシートは、シート全体でみると、基板側端部上のシート厚さと基板中央部上でのシートの厚さの差が小さくなり、シート厚さの分布が低減される。 Therefore, in the present invention, as shown in FIGS. 5 and 6, the sectional area of the convex portion 107p of the substrate side portion 107 located in the vicinity of the substrate side end portion 107e is compared with the sectional area of the convex portion 106p of the substrate middle portion 106. By increasing the thermal resistance value, the thermal resistance value of the convex portion 106p of the substrate middle portion 106 can be made larger than the thermal resistance value of the convex portion 107p of the substrate end portion 107. As a result, the sheet formed on the main surface of the substrate according to the present embodiment is compared with the sheet formed on the main surface of the conventional substrate using the convex portions having the same cross-sectional area at the substrate end and in the middle of the substrate. It is relatively thick on the substrate edge and relatively thin on the substrate center. That is, the sheet formed on the main surface of the substrate according to the present embodiment has a small difference between the sheet thickness on the substrate side end and the sheet thickness on the substrate center when the entire sheet is viewed. The thickness distribution is reduced.

ここで、基板中部１０６の凸部１０６ｐの熱抵抗値を大きくする方法としては、特に制限はなく、図６に示すような凸部１０１ｐの裾部分を切削する方法の他、凸部１０６ｐの凸部形状そのものを鋭角化する方法がある（図示せず）。 Here, the method for increasing the thermal resistance value of the convex portion 106p of the substrate middle portion 106 is not particularly limited. In addition to the method of cutting the bottom portion of the convex portion 101p as shown in FIG. There is a method of sharpening the part shape itself (not shown).

また、基板１００の融液への浸漬方向と垂直な方向において、基板中央部１０６ｃから基板側端部１０７ｅへ向かって凸部１０７ｐの熱抵抗値を徐々に小さくすることにより、基板の主面上に形成されるシートの厚さの分布の傾きを低減することが可能となる。 Further, in the direction perpendicular to the direction of immersion of the substrate 100 in the melt, the thermal resistance value of the convex portion 107p is gradually reduced from the substrate central portion 106c toward the substrate-side end portion 107e, so that It is possible to reduce the slope of the thickness distribution of the sheet formed on the sheet.

（実施形態３）
本発明にかかるシート製造方法のさらに他の実施形態は、図８および図９を参照して、実施形態１と同様に、一方の主面１００ｍに複数の凸部１００ｐを有する基板１００の主面１００ｍを金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、材料の固相を主面上で凸部１００ｐを起点として成長させることにより、材料を主成分とするシートを得るシート製造方法であって、基板１００の融液への浸漬方向Ｄにおいて基板前部１０２（領域Ｆ）の凸部１０２ｐの熱抵抗値が基板後部１１４（領域Ｂ）の凸部１１４ｐの熱抵抗値に比べて大きいことを特徴とする。 (Embodiment 3)
Still another embodiment of the sheet manufacturing method according to the present invention is the main surface of the substrate 100 having a plurality of convex portions 100p on one main surface 100m, as in the first embodiment, with reference to FIGS. 100 m is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and a solid phase of the material is grown on the main surface starting from the convex portion 100p, so that the material is a main component. In the sheet manufacturing method for obtaining a sheet, in the immersion direction D of the substrate 100 in the melt, the thermal resistance value of the convex portion 102p of the substrate front portion 102 (region F) is equal to that of the convex portion 114p of the substrate rear portion 114 (region B). It is characterized by being larger than the thermal resistance value.

ここで、基板後部の凸部に比べて基板前部の凸部の熱抵抗値を大きくする方法が、実施形態１においては基板前部１０１の凸部１０１ｐの裾部分を切削することまたは凸部を鋭角化する方法であるのに対して、本実施形態においては基板前部１０２の凸部１０２ｐの構成材料の熱伝導率を基板後部１１４の凸部１１４ｐの構成材料の熱伝導率に比べて小さくする方法である点で相違する。すなわち、本実施形態においては、熱伝導率の異なる材料を組み合わせることにより、基板前部１０２の凸部１０２ｐの熱抵抗値を基板後部１１４の凸部１１４ｐの熱抵抗値に比べて大きくして、基板１００の主面１００ｍ上に形成されるシートの厚さの分布を低減する。 Here, the method of increasing the thermal resistance value of the convex portion at the front portion of the substrate as compared with the convex portion at the rear portion of the substrate is the cutting of the bottom portion of the convex portion 101p of the front portion 101 of the substrate or the convex portion in the first embodiment. In this embodiment, the thermal conductivity of the constituent material of the convex portion 102p of the substrate front portion 102 is compared with the thermal conductivity of the constituent material of the convex portion 114p of the substrate rear portion 114. It is different in that it is a method of reducing the size. That is, in this embodiment, by combining materials having different thermal conductivities, the thermal resistance value of the convex portion 102p of the substrate front portion 102 is made larger than the thermal resistance value of the convex portion 114p of the substrate rear portion 114, The thickness distribution of the sheet formed on the main surface 100m of the substrate 100 is reduced.

たとえば、基板前部１０２の凸部１０２ｐの構成材料の熱伝導率κ₁とし基板後部１１４の凸部１１４ｐの構成材料の熱伝導率κ₂とするとき、κ₁＜κ₂となるような材料を用いると、基板前部における融液から基板側への熱移動量Ｑ₁と基板後部における融液から基板側への熱移動量Ｑ₂との関係はＱ₁＜Ｑ₂となる。このため、基板前部において、シートの結晶成長が抑制され、シートの厚さが低減する。この結果、基板の浸漬方向におけるシートの厚さの分布は低減する。また、本実施形態においては、基板前部の凸部の構成材料と基板後部の凸部の構成材料とを互いに熱伝導率の異なる材料を用いることにより、基板全体の凸部の形状を同一にでき、基板表面の凹凸加工が同一刃物で加工することが可能となり、基板の生産性が向上する。図８および図９においては、２種類の異なる熱伝導率を持つ材料の組み合わせで基板を構成しているが、３種類以上の異なる熱伝導率を持つ材料を組み合わせて基板を構成してもよい。 For example, when the thermal conductivity κ ₁ of the constituent material of the convex portion 102p of the substrate front portion 102 and the thermal conductivity κ ₂ of the constituent material of the convex portion 114p of the substrate rear portion 114 are given, κ ₁ <κ ₂ Is used, the relationship between the heat transfer amount Q ₁ from the melt at the front portion of the substrate to the substrate side and the heat transfer amount Q ₂ from the melt at the rear portion of the substrate to the substrate side is Q ₁ <Q ₂ . For this reason, in the front part of the substrate, the crystal growth of the sheet is suppressed, and the thickness of the sheet is reduced. As a result, the sheet thickness distribution in the substrate immersion direction is reduced. Further, in this embodiment, by using materials having different thermal conductivities for the constituent material of the convex part at the front part of the substrate and the constituent material of the convex part at the rear part of the substrate, the shape of the convex part of the entire substrate is made the same. In addition, it is possible to process the unevenness of the substrate surface with the same cutting tool, thereby improving the productivity of the substrate. 8 and 9, the substrate is composed of a combination of two types of materials having different thermal conductivities, but the substrate may be composed of a combination of three or more types of materials having different thermal conductivities. .

（実施形態４）
本発明にかかるシート製造方法のさらに他の実施形態は、図１０および図１１を参照して、実施形態２と同様に、一方の主面１００ｍに複数の凸部１００ｐを有する基板１００の主面１００ｍを金属材料および半導体材料のうち少なくともいずれか一方を含有する材料の融液に接触させ、材料の固相を主面上で凸部１００ｐを起点として成長させることにより、材料を主成分とするシートを得るシート製造方法であって、基板１００の融液への浸漬方向Ｄと垂直な方向において基板中部１０６（領域Ｃ）の凸部１０６ｐの熱抵抗値が基板側部１１７（領域Ｓ）の凸部１１７ｐの熱抵抗値に比べて大きいことを特徴とする。 (Embodiment 4)
Still another embodiment of the sheet manufacturing method according to the present invention is the main surface of the substrate 100 having a plurality of convex portions 100p on one main surface 100m, as in the second embodiment, with reference to FIGS. 100 m is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and a solid phase of the material is grown on the main surface starting from the convex portion 100p, so that the material is a main component. In the sheet manufacturing method for obtaining a sheet, the thermal resistance value of the convex portion 106p of the substrate middle portion 106 (region C) in the direction perpendicular to the immersion direction D of the substrate 100 in the melt is that of the substrate side portion 117 (region S). It is characterized by being larger than the thermal resistance value of the convex portion 117p.

ここで、基板後部の凸部に比べて基板前部の凸部の熱抵抗値を大きくする方法が、実施形態２においては基板中部１０６の凸部１０６ｐの裾部分を切削することまたは凸部１０６ｐを鋭角化する方法であるのに対して、本実施形態においては基板中部１０６の凸部１０６ｐの構成材料の熱伝導率を基板後部１１７の凸部１１７ｐの構成材料の熱伝導率に比べて小さくする方法である点で相違する。すなわち、本実施形態においては、熱伝導率の異なる材料を組み合わせることにより、基板中部１０６の凸部１０６ｐの熱抵抗値を基板側部１１７の凸部１１７ｐの熱抵抗値に比べて大きくして、基板１００の主面１００ｍ上に形成されるシートの厚さの分布を低減する。 Here, the method of increasing the thermal resistance value of the convex portion at the front portion of the substrate as compared with the convex portion at the rear portion of the substrate is to cut the skirt portion of the convex portion 106p of the central portion 106 of the substrate or the convex portion 106p. In this embodiment, the thermal conductivity of the constituent material of the convex portion 106p of the substrate middle portion 106 is smaller than the thermal conductivity of the constituent material of the convex portion 117p of the substrate rear portion 117. It is different in that it is a method to do. That is, in this embodiment, by combining materials having different thermal conductivities, the thermal resistance value of the convex portion 106p of the substrate middle portion 106 is made larger than the thermal resistance value of the convex portion 117p of the substrate side portion 117, The thickness distribution of the sheet formed on the main surface 100m of the substrate 100 is reduced.

たとえば、基板中部１０６の凸部１０６ｐの構成材料の熱伝導率κ₃とし基板後部１１７の凸部１１７ｐの構成材料の熱伝導率κ₄とするとき、κ₃＜κ₄となるような材料を用いると、基板中部における融液から基板側への熱移動量Ｑ₃と基板側部における融液から基板側への熱移動量Ｑ₄との関係はＱ₃＜Ｑ₄となる。このため、基板中部において、シートの結晶成長が抑制され、シートの厚さが低減する。この結果、基板の浸漬方向におけるシートの厚さの分布は低減する。また、本実施形態においては、基板中部の凸部の構成材料と基板側部の凸部の構成材料とを互いに熱伝導率の異なる材料を用いることにより、基板全体の凸部の形状を同一にでき、基板表面の凹凸加工が同一刃物で加工することが可能となり、基板の生産性が向上する。 For example, when the thermal conductivity kappa ₄ of the constituent material of the protrusions 117p of the substrate rear 117 and the thermal conductivity kappa ₃ of the material of the protrusion 106p of the substrate central 106, a material such that κ ₃ <κ ₄ When used, the relationship between the heat transfer amount Q ₃ from the melt in the middle of the substrate to the substrate side and the heat transfer amount Q ₄ from the melt to the substrate side in the substrate side portion is Q ₃ <Q ₄ . For this reason, in the central part of the substrate, the crystal growth of the sheet is suppressed, and the thickness of the sheet is reduced. As a result, the sheet thickness distribution in the substrate immersion direction is reduced. Further, in the present embodiment, by using materials having different thermal conductivities for the constituent material of the convex part in the middle part of the substrate and the constituent material of the convex part in the side part of the substrate, the shape of the convex part of the entire substrate is made the same. In addition, it is possible to process the unevenness of the substrate surface with the same cutting tool, thereby improving the productivity of the substrate.

（実施形態５）
本発明にかかる光電変換素子は、図１７を参照して、半導体材料を主成分として、実施形態１〜４の製造方法により得られたシリコンのシートを光電変換部に用いたことを特徴とする。具体的には、図１７を参照して、ｐ型シリコンシート１７１の一方の主面（受光面）およびその内側にｎ層１７２が形成され、ｎ層１７２上に反射防止膜としての窒化シリコン膜１７４が形成され、表面電極１７５がシリコン窒化膜１７４を貫通して、ｎ層１７２と接している。また、ｐ型シリコンシート１７１にｐ型シリコンシートの他方の主面（裏面）およびその内側にｐ⁺層１７３が形成され、ｐ⁺層１７３上に裏面電極１７６が形成されている。 (Embodiment 5)
With reference to FIG. 17, the photoelectric conversion element according to the present invention is characterized in that a semiconductor sheet is used as a main component and a silicon sheet obtained by the manufacturing method of Embodiments 1 to 4 is used for a photoelectric conversion unit. . Specifically, referring to FIG. 17, an n layer 172 is formed on one main surface (light receiving surface) of p-type silicon sheet 171 and on the inner side thereof, and a silicon nitride film as an antireflection film is formed on n layer 172. 174 is formed, and the surface electrode 175 penetrates the silicon nitride film 174 and is in contact with the n layer 172. A p ⁺ layer 173 is formed on the p-type silicon sheet 171 on the other main surface (back surface) of the p-type silicon sheet and on the inside thereof, and a back electrode 176 is formed on the p ⁺ layer 173.

シートとしてシリコンシートを製造する場合についての実施例を、図を用いて以下に具体的に説明する。 An example of manufacturing a silicon sheet as a sheet will be specifically described below with reference to the drawings.

（実施例１）
図１２を参照して、得られる結晶シートの比抵抗が２Ω・ｃｍになるようにボロン濃度を調整したシリコン原料を、高純度黒鉛製の坩堝３０１に入れ、その坩堝３０１を装置内に設置した。次に、チャンバ３０２内の真空引きを行い、その後Ａｒガスを導入し、８００ｈＰａを保ちつつ、常に１００Ｌ／ｍｉｎでチャンバ上部よりＡｒガスを導入したままにした。 Example 1
Referring to FIG. 12, a silicon raw material whose boron concentration was adjusted so that the specific resistance of the obtained crystal sheet was 2 Ω · cm was placed in crucible 301 made of high-purity graphite, and the crucible 301 was installed in the apparatus. . Next, the chamber 302 was evacuated, and then Ar gas was introduced. Ar gas was always introduced from the top of the chamber at 100 L / min while maintaining 800 hPa.

次に、坩堝３０１の周囲に配置されているシリコンを溶融するためのヒータ３０３の制御用熱電対の設定温度を１５００℃に設定し、完全にシリコンを溶融状態にして融液３０６とする。最初に仕込んだシリコンは、溶融することで嵩が低くなるために、追加でシリコンを投入することにより、シリコン融液面の高さを所定の高さにした。その後、制御温度を１４３０℃に設定し、３０分間保持し融液温度の安定化を図った。 Next, the set temperature of the thermocouple for controlling the heater 303 for melting the silicon disposed around the crucible 301 is set to 1500 ° C. to completely melt the silicon to obtain a melt 306. Since the initially charged silicon becomes low in volume when melted, additional silicon is added to bring the height of the silicon melt surface to a predetermined height. Thereafter, the control temperature was set to 1430 ° C. and held for 30 minutes to stabilize the melt temperature.

その後、浸漬装置３０４の先端にシートを成長させるための、黒鉛で形成された基板１００をセットした。このとき用いる基板１００の主面１００ｍには、図１に示すように、凸部１００ｐが形成されており、シリコンの融液３０６への浸漬方向Ｄにおいて基板前部１０１の凸部１０１ｐの熱抵抗値が、基板後部１０４の凸部１０４ｐの熱抵抗値に比べて大きなものであった。凸部１００ｐは四角錐で構成されており、その底部の一辺の長さは２ｍｍ、高さは０．５ｍｍであった。また、基板前部１０１の凸部１０１ｐの四角錐の裾部の切削深さは、基板の前後方向の２辺について、それぞれ０．３ｍｍ切削されており、切削されている凸部の範囲は基板前端部より６０ｍｍであった。基板１００の外寸は１５０ｍｍ×１５０ｍｍであり、基板１００の厚さは一方の主面の凸部の頂点から他方の主面までが２０ｍｍであった。 Thereafter, a substrate 100 made of graphite for growing a sheet was set on the tip of the dipping device 304. As shown in FIG. 1, a convex portion 100p is formed on the main surface 100m of the substrate 100 used at this time, and the thermal resistance of the convex portion 101p of the substrate front portion 101 in the immersion direction D of the silicon melt 306. The value was larger than the thermal resistance value of the convex portion 104p of the substrate rear portion 104. The convex part 100p was comprised by the square pyramid, the length of the one side of the bottom part was 2 mm, and the height was 0.5 mm. In addition, the cutting depth of the bottom of the quadrangular pyramid of the convex portion 101p of the substrate front portion 101 is cut by 0.3 mm for each of two sides in the front-rear direction of the substrate, and the range of the cut convex portion is the substrate. It was 60 mm from the front end. The outer dimension of the substrate 100 was 150 mm × 150 mm, and the thickness of the substrate 100 was 20 mm from the top of the convex portion of one main surface to the other main surface.

次に、上記基板１００を、浸漬深さ１０ｍｍでシリコンの融液３０６中へ浸漬し、基板の主面１００上にシート２００を成長させた。その後、基板１００をコンベア３０８にて副室３０９に搬送し、副室３０９と主室３１１を仕切るゲートバルブ３１０を閉じた後、副室３０９内をロータリーポンプで真空排気し、大気で置換後、副室３０９外へシート２００が形成された状態の基板１００を取り出す。基板１００上に形成されたシート２００は容易に剥離可能である。その後、レーザー切断装置を用いて、１２６ｍｍ×１２６ｍｍに切断した。 Next, the substrate 100 was immersed in a silicon melt 306 at an immersion depth of 10 mm, and a sheet 200 was grown on the main surface 100 of the substrate. Thereafter, the substrate 100 is conveyed to the sub chamber 309 by the conveyor 308, the gate valve 310 that partitions the sub chamber 309 and the main chamber 311 is closed, the inside of the sub chamber 309 is evacuated by a rotary pump, and replaced with the atmosphere. The substrate 100 with the sheet 200 formed outside the sub chamber 309 is taken out. The sheet 200 formed on the substrate 100 can be easily peeled off. Then, it cut | disconnected to 126 mm x 126 mm using the laser cutting device.

切断されたシートの厚さの分布を静電容量センサーにて測定し、シートの前端から浸漬方向に１０ｍｍ毎の平均の厚さの分布を図１３の実線で示す。また、従来の同一形状の凸部で形成された基板を用いた他は実施例１と同様にして作製されたシート（比較例１という、以下同じ）の厚さの分布を図１３の破線で示す。図１３を参照して、実施例１のシートは比較例１のシートに比べて、シートの前端部における最大厚さは約５０μｍ低減し、シート全体の平均厚さは約２０μｍ低減した。すなわち、実施例１のシートは比較例１のシートに比べてシート厚さの分布が低減した。 The thickness distribution of the cut sheet is measured by a capacitance sensor, and the average thickness distribution every 10 mm from the front end of the sheet in the immersion direction is shown by a solid line in FIG. Further, the thickness distribution of a sheet (referred to as Comparative Example 1 hereinafter) that is manufactured in the same manner as in Example 1 except that a conventional substrate formed with convex portions having the same shape is used is indicated by a broken line in FIG. Show. Referring to FIG. 13, the maximum thickness at the front end of the sheet of Example 1 was reduced by about 50 μm and the average thickness of the entire sheet was reduced by about 20 μm, compared to the sheet of Comparative Example 1. That is, the sheet thickness of the sheet of Example 1 was reduced compared to the sheet of Comparative Example 1.

次に、図１７を参照して、レーザー切断により得られた１２６ｍｍ×１２６ｍｍサイズのｐ型シリコンシートを用いて太陽電池の作製を行った。得られたｐ型シリコンシート１７１は、硝酸とフッ酸との混合溶液でエッチングを行い、その後、水酸化ナトリウム水溶液を用いてアルカリエッチングを行った。その後ＰＯＣｌ₃拡散によりｐ型シリコンシートの両側の主面およびその内側にｎ層１７２を形成した。次に、ｎ層１７２の形成の際に、固相シリコンのシート表面に形成されたＰＳＧ（リン−珪酸ガラス）膜をフッ酸で除去した後、太陽電池の受光面側になる一方の主面のｎ層１７２上にプラズマＣＶＤ法を用いてシリコン窒化膜１７４を形成した。次に、このシリコン窒化膜１７４上に、スクリーン印刷法により銀ペーストをグリッド状に形成し焼成することにより、シリコン窒化膜１７４を貫通してｎ層１７２と接触する表面電極１７５を形成した。次に、太陽電池の裏面側になる他方の主面およびその内側に形成されているｎ層を硝酸とフッ酸との混合溶液でエッチング除去し、ｐ型シリコンシート１７１の裏面を露出させた。次に、ｐ型シリコンシート１７１の裏面上にスクリーン印刷法を用いて、Ａｌペーストを印刷し焼成することにより、ｐ型シリコン１７１の裏面上に裏面電極１７６（裏面Ａｌ電極）を形成するとともに、ｐ型シリコンシート１７１にｐ型シリコンシートの裏面およびその内側にｐ⁺層１７３を同時に形成した。その後、半田コートを行い、太陽電池を作製した。 Next, referring to FIG. 17, a solar cell was manufactured using a 126 mm × 126 mm p-type silicon sheet obtained by laser cutting. The obtained p-type silicon sheet 171 was etched with a mixed solution of nitric acid and hydrofluoric acid, and then alkali-etched with an aqueous sodium hydroxide solution. Thereafter, n-layers 172 were formed on the principal surfaces on both sides of the p-type silicon sheet and inside thereof by POCl ₃ diffusion. Next, when the n-layer 172 is formed, the PSG (phosphorus-silicate glass) film formed on the surface of the solid-phase silicon sheet is removed with hydrofluoric acid, and then one main surface on the light-receiving surface side of the solar cell. A silicon nitride film 174 was formed on the n layer 172 by plasma CVD. Next, a surface paste 175 penetrating the silicon nitride film 174 and in contact with the n layer 172 was formed on the silicon nitride film 174 by forming and baking a silver paste in a grid shape by a screen printing method. Next, the other main surface which becomes the back surface side of the solar cell and the n layer formed on the inside thereof were removed by etching with a mixed solution of nitric acid and hydrofluoric acid to expose the back surface of the p-type silicon sheet 171. Next, an Al paste is printed and baked on the back surface of the p-type silicon sheet 171 using a screen printing method, thereby forming a back surface electrode 176 (back surface Al electrode) on the back surface of the p-type silicon 171. A p ⁺ layer 173 was simultaneously formed on the back surface and the inside of the p-type silicon sheet 171 on the p-type silicon sheet 171. Thereafter, solder coating was performed to produce a solar cell.

上記方法にて作製された太陽電池１００枚を、ＡＭ１．５（１００ｍＷ／ｃｍ²）の照射下にてセル特性の測定を行ったところ、平均開放電圧６１２ｍＶ、平均短絡電流３１．２ｍＡ／ｃｍ²、平均フィルファクター０．７４５、平均変換効率１４．２％と良好な結果が得られた。 When cell characteristics of 100 solar cells produced by the above method were measured under irradiation of AM 1.5 (100 mW / cm ² ), an average open circuit voltage of 612 mV and an average short circuit current of 31.2 mA / cm ^{2 were obtained.} Good results were obtained with an average fill factor of 0.745 and an average conversion efficiency of 14.2%.

（実施例２）
図４に示すような基板１００の浸漬方向に基板前端部１０１ｅから基板中央部１０５ｃにかけて、凸部１０１ｐの熱抵抗値を徐々に小さくした基板１００を用いたこと以外は、実施例１と同様にしてシートを作製した。実施例２で用いた基板は、具体的には基板中央部１０５ｃから基板後端部１０４ｅにかけての一定形状の凸部は一辺２ｍｍ、高さ０．５ｍｍの四角錐で構成されており、基板前端部１０１ｅから６０ｍｍ基板中央部１０５ｃに入った位置から、基板前端部１０１ｅにかけての基板前部１０１の凸部１０１ｐの四角錐は、浸漬方向に対して前後２辺が一凸部あたり０．０１５ｍｍづつ切削深さを大きくしていった。また、作製された１２６ｍｍ×１２６ｍｍのシートの厚さの分布を実施例１と同様にして測定し、シートの前端から浸漬方向に１０ｍｍ毎の平均の厚さの分布を図１４の実線で示す。また、従来の同一形状の凸部で形成された基板を用いた他は実施例２と同様にして作製されたシート（比較例２という、以下同じ）の厚さの分布を図１４の破線で示す。図１４を参照して、実施例２のシートは比較例２のシートに比べて、シートの前端部における最大厚さは約９０μｍ低減し、シート全体の平均厚さは約３４μｍ低減した。すなわち、実施例２のシートは比較例２のシートに比べてシート厚さの分布が大きく低減した。 (Example 2)
Except for using the substrate 100 in which the thermal resistance value of the convex portion 101p is gradually reduced from the substrate front end portion 101e to the substrate center portion 105c in the immersion direction of the substrate 100 as shown in FIG. A sheet was prepared. Specifically, the substrate used in Example 2 is formed of a quadrangular pyramid having a side of 2 mm and a height of 0.5 mm, and a convex portion having a fixed shape from the substrate center portion 105 c to the substrate rear end portion 104 e. As for the quadrangular pyramid of the convex part 101p of the front part 101 of the substrate from the position where it enters the central part 105c of the board 60mm from the part 101e, the front and rear sides of the convex part 101p are 0.015 mm per convex part with respect to the immersion direction. The cutting depth was increased. Further, the thickness distribution of the produced 126 mm × 126 mm sheet was measured in the same manner as in Example 1, and the average thickness distribution every 10 mm from the front end of the sheet in the immersion direction is shown by the solid line in FIG. Further, the thickness distribution of a sheet (referred to as Comparative Example 2, hereinafter the same) manufactured in the same manner as in Example 2 except that a conventional substrate formed of convex portions having the same shape is used is indicated by a broken line in FIG. Show. Referring to FIG. 14, the maximum thickness at the front end of the sheet of Example 2 was reduced by about 90 μm, and the average thickness of the entire sheet was reduced by about 34 μm, compared to the sheet of Comparative Example 2. That is, the sheet thickness distribution of the sheet of Example 2 was greatly reduced as compared with the sheet of Comparative Example 2.

（参考例３）
図５および図６に示すような基板１００の融液への浸漬方向と垂直な方向において基板中部１０６の凸部１０６ｐの熱抵抗値が基板端部１０７の凸部１０７ｐの熱抵抗値に比べて大きい基板１００を用いたこと以外は、実施例１と同様にしてシートを作製した。参考例３で用いた基板は、具体的には、基板の凸部は四角錐で構成されており、その底部の一辺の長さは２ｍｍ、高さは０．５ｍｍであった。また、基板中部の凸部の四角錐の裾部の切削深さは、浸漬方向に対して垂直な辺をそれぞれ０．３ｍｍづつ切削した。基板の外寸は２００ｍｍ×２００ｍｍ、基板の厚みは凸部頂点まで２０ｍｍであった。また切削された凸部１０６ｐの四角錐が占める範囲は、浸漬方向に対して、中央から左右５０ｍｍの範囲である。また、作製された結晶シートを１５５×１５５ｍｍに切断し、シートの厚さの分布を静電容量センサーにて測定し、浸漬方向と垂直な方向について１０ｍｍ毎の平均の厚さの分布を図１５の実線で示す。また、従来の同一形状の凸部で形成された基板を用いた他は参考例３と同様にして作製されたシート（比較例３という、以下同じ）の厚さの分布を図１５の破線で示す。図１５を参照して、参考例３のシートにおける最大厚さと最小厚さとの差は比較例３のシートに比べて約７０μｍ低減した。また、比較例３のシートの平均厚さが３９３μｍであったのに対し、参考例３のシートの平均厚さは３８０μｍに低減した。 ( Reference Example 3)
5 and 6, the thermal resistance value of the convex portion 106 p of the central portion 106 of the substrate 100 in the direction perpendicular to the immersion direction of the substrate 100 in the melt is larger than the thermal resistance value of the convex portion 107 p of the substrate end portion 107. A sheet was produced in the same manner as in Example 1 except that the large substrate 100 was used. Specifically, in the substrate used in Reference Example 3, the convex portion of the substrate was formed of a quadrangular pyramid, and the length of one side of the bottom portion was 2 mm and the height was 0.5 mm. Moreover, the cutting depth of the skirt part of the quadrangular pyramid of the convex part in the middle part of the substrate was cut by 0.3 mm at each side perpendicular to the immersion direction. The outer dimension of the substrate was 200 mm × 200 mm, and the thickness of the substrate was 20 mm up to the top of the convex portion. Further, the range occupied by the quadrangular pyramid of the cut projection 106p is a range of 50 mm from the center to the left and right with respect to the immersion direction. Further, the produced crystal sheet was cut into 155 × 155 mm, the thickness distribution of the sheet was measured with a capacitance sensor, and the average thickness distribution every 10 mm in the direction perpendicular to the dipping direction is shown in FIG. Indicated by the solid line. Further, the thickness distribution of a sheet (referred to as Comparative Example 3, hereinafter the same) manufactured in the same manner as in Reference Example 3 except that a conventional substrate formed of convex portions having the same shape is used is indicated by a broken line in FIG. Show. Referring to FIG. 15, the difference between the maximum thickness and the minimum thickness in the sheet of Reference Example 3 was reduced by about 70 μm compared to the sheet of Comparative Example 3. Further, the average thickness of the sheet of Comparative Example 3 was 393 μm, whereas the average thickness of the sheet of Reference Example 3 was reduced to 380 μm.

（実施例４）
図８および図９に示すような基板１００の融液への浸漬方向において基板前部１０２の凸部１０２ｐの構成材料の熱伝導率が基板後部１１４の凸部１１４ｐの構成材料の熱伝導率に比べて小さい基板１００を用いたこと以外は、実施例１と同様にしてシートを作製した。実施例４で用いた基板は、具体的には、基板外寸は１５０×１５０ｍｍで、基板前部１０２の領域Ｆは基板前端部１０２ｅから６０ｍｍの範囲であり、基板後部１１４の領域Ｂは９０ｍｍの範囲であった。また、基板前部１０２の凸部１０２ｐの構成材料の熱伝導率は１０４Ｗ・ｍ^-1・Ｋ^-1であり基板後部１１４の凸部１１４ｐの構成材料の熱伝導率は１３９Ｗ・ｍ^-1・Ｋ^-1であった。また、作製された１２６ｍｍ×１２６ｍｍのシートの厚さの分布を実施例１と同様にして測定し、シートの前端から浸漬方向に１０ｍｍ毎の平均の厚さの分布を図１６の実線で示す。また、従来の同一材料および同一形状の凸部で形成された基板を用いた他は実施例４と同様にして作製されたシート（比較例４という、以下同じ）の厚さの分布を図１６の破線で示す。図１６を参照して、実施例４のシートは比較例４のシートに比べて、シートの前端部における最大厚さは約７０μｍ低減し、シート全体の平均厚さは約１５μｍ低減した。すなわち、実施例４のシートは比較例４のシートに比べてシート厚さの分布が低減した。 Example 4
In the direction of immersion of the substrate 100 in the melt as shown in FIGS. 8 and 9, the thermal conductivity of the constituent material of the convex portion 102p of the substrate front portion 102 is changed to the thermal conductivity of the constituent material of the convex portion 114p of the substrate rear portion 114. A sheet was produced in the same manner as in Example 1 except that a smaller substrate 100 was used. Specifically, the substrate used in Example 4 has a substrate outer dimension of 150 × 150 mm, the region F of the substrate front portion 102 is in the range of 60 mm from the substrate front end portion 102e, and the region B of the substrate rear portion 114 is 90 mm. Range. The thermal conductivity of the constituent material of the convex portion 102p of the substrate front portion 102 is 104 W · m ⁻¹ · K ⁻¹ , and the thermal conductivity of the constituent material of the convex portion 114 p of the substrate rear portion 114 is 139 W · m ⁻¹ · K- ¹ . Further, the thickness distribution of the produced 126 mm × 126 mm sheet was measured in the same manner as in Example 1, and the average thickness distribution every 10 mm in the immersion direction from the front end of the sheet is shown by a solid line in FIG. Further, FIG. 16 shows the thickness distribution of a sheet (referred to as Comparative Example 4 hereinafter) manufactured in the same manner as in Example 4 except that a conventional substrate formed of the same material and convex portions of the same shape is used. This is indicated by a broken line. Referring to FIG. 16, the maximum thickness at the front end portion of the sheet of Example 4 was reduced by about 70 μm and the average thickness of the entire sheet was reduced by about 15 μm, compared to the sheet of Comparative Example 4. That is, the sheet of Example 4 has a reduced sheet thickness distribution compared to the sheet of Comparative Example 4.

今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記した説明でなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内のすべての変更が含まれることが意図される。 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.

本発明にかかるシート製造用基板の一例を示す概略斜視図である。It is a schematic perspective view which shows an example of the board | substrate for sheet | seat manufacture concerning this invention. 図１のＩＩにおける概略断面図である。It is a schematic sectional drawing in II of FIG. 本発明にかかるシート製造用基板の他の例を示す概略断面図である。It is a schematic sectional drawing which shows the other example of the board | substrate for sheet manufacture concerning this invention. 本発明にかかるシート製造用基板のさらに他の例を示す概略断面図である。It is a schematic sectional drawing which shows the further another example of the board | substrate for sheet | seat manufacture concerning this invention. 本発明にかかるシート製造用基板のさらに他の例を示す概略斜視図である。It is a schematic perspective view which shows the further another example of the board | substrate for sheet | seat manufacture concerning this invention. 図５のＶＩにおける概略断面図である。It is a schematic sectional drawing in VI of FIG. 本発明にかかるシート製造用基板のさらに他の例を示す概略断面図である。It is a schematic sectional drawing which shows the further another example of the board | substrate for sheet | seat manufacture concerning this invention. 本発明にかかるシート製造用基板のさらに他の例を示す概略斜視図である。It is a schematic perspective view which shows the further another example of the board | substrate for sheet | seat manufacture concerning this invention. 図８のＩＸにおける概略断面図である。It is a schematic sectional drawing in IX of FIG. 本発明にかかるシート製造用基板のさらに他の例を示す概略斜視図である。It is a schematic perspective view which shows the further another example of the board | substrate for sheet | seat manufacture concerning this invention. 図１０のＸＩにおける概略断面図である。It is a schematic sectional drawing in XI of FIG. 本発明で用いられるシート製造用の装置を示す概略断面図である。It is a schematic sectional drawing which shows the apparatus for sheet | seat manufacture used by this invention. 実施例１および比較例１で得られたシートの厚さの分布を示す図である。It is a figure which shows distribution of the thickness of the sheet | seat obtained in Example 1 and Comparative Example 1. FIG. 実施例２および比較例２で得られたシートの厚さの分布を示す図である。It is a figure which shows distribution of the thickness of the sheet | seat obtained in Example 2 and Comparative Example 2. FIG. 実施例３および比較例３で得られたシートの厚さの分布を示す図である。It is a figure which shows distribution of the thickness of the sheet | seat obtained in Example 3 and Comparative Example 3. FIG. 実施例４および比較例４で得られたシートの厚さの分布を示す図である。It is a figure which shows distribution of the thickness of the sheet | seat obtained in Example 4 and Comparative Example 4. FIG. 本発明にかかる光電変換素子の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the photoelectric conversion element concerning this invention.

Explanation of symbols

１００基板、１００ｍ主面、１００ｐ，１０１ｐ，１０２ｐ，１０４ｐ，１０６ｐ，１０７ｐ，１１４ｐ，１１７ｐ凸部、１０１，１０２基板前部、１０２ｅ基板前端部、１０４，１１４基板後部、１０４ｅ基板後端部、１０５ｃ，１０６ｃ基板中央部、１０６基板中部、１０７，１１７基板側部、１０７ｅ基板側端部、１７１ｐ型シリコンシート、１７２ｎ層、１７３ｐ⁺層、１７４窒化シリコン膜、１７５表面電極、１７６裏面電極、２００シート、３０２チャンバ、３０３ヒータ、３０４浸漬装置、３０６融液、３０８コンベア、３０９副室、３１０ゲートバルブ、３１１主室、Ｂ基板後部の領域、Ｃ基板中部の領域、Ｄ浸漬方向、Ｆ基板前部の領域、Ｓ基板側部の領域。 100 substrate, 100 m main surface, 100p, 101p, 102p, 104p, 106p, 107p, 114p, 117p convex portion, 101, 102 substrate front portion, 102e substrate front end portion, 104, 114 substrate rear portion, 104e substrate rear end portion, 105c , 106c Substrate center part, 106 Substrate middle part, 107,117 Substrate side part, 107e Substrate side end part, 171 p-type silicon sheet, 172 n layer, 173 p ⁺ layer, 174 silicon nitride film, 175 surface electrode, 176 back electrode , 200 sheets, 302 chamber, 303 heater, 304 dipping device, 306 melt, 308 conveyor, 309 sub chamber, 310 gate valve, 311 main chamber, B substrate rear region, C substrate middle region, D immersion direction, F The area at the front of the substrate, the area at the side of the S substrate.

Claims

The main surface of the substrate having a plurality of convex portions on one main surface is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and a solid phase of the material is placed on the main surface. A sheet manufacturing method for obtaining a sheet containing the material as a main component by growing the protrusion as a starting point,
The sheet is characterized in that the thermal resistance value of the convex part at the front part of the substrate in the immersion direction of the substrate in the melt is larger than the thermal resistance value of the convex part at the rear part of the substrate in the immersion direction of the substrate. Production method.

2. The sheet manufacturing method according to claim 1, wherein in the immersion direction of the substrate in the melt, the thermal resistance value of the convex portion gradually decreases from the front end portion of the substrate toward the central portion of the substrate.

The thermal resistance value of the convex portion is changed by changing a thermal conductivity of a constituent material of the convex portion or a cross-sectional area of the convex portion. Sheet manufacturing method.

The thermal conductivity of the constituent material of the convex part at the front part of the substrate is smaller than the thermal conductivity of the constituent material of the convex part at the rear part of the substrate in the immersion direction of the substrate in the melt. Item 2. The sheet manufacturing method according to Item 1.

One main surface has a plurality of convex portions, the main surface is brought into contact with a melt of a material containing at least one of a metal material and a semiconductor material, and the material is a main component on the main surface. A sheet manufacturing substrate for manufacturing a sheet to be manufactured,
The sheet is characterized in that the thermal resistance value of the convex part at the front part of the substrate in the immersion direction of the substrate in the melt is larger than the thermal resistance value of the convex part at the rear part of the substrate in the immersion direction of the substrate. Manufacturing substrate.