JP2011249523A - Wafer manufacturing method and wafer manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer manufacturing method and a wafer manufacturing apparatus which can restrain such defect occurrence of a wafer as chipping, breakage, and cracking.SOLUTION: Flat four side faces 1a of multiple ingots 1 formed as square poles are bonded together without any gap by an adhesive 3 so that an intermediate plate member 2 is sandwiched therebetween in order to form an ingot connected body B. The ingot connected body B and a cutter S are moved in the direction relatively crossing the longitudinal direction of the ingot 1 to slice the whole ingot connected body B so that wafers W which are cut out from the ingot 1 as multiple coupling pieces B1 and an intermediate piece M which is cut out from the intermediate plate member 2 are cut out as being bonded together. Therefore, vibration from the cutter S does not easily get delivered to the corners and edges of each wafer W, and after that adhesive strength of the adhesive 3 in the coupling pieces B1 is reduced in order to separate the wafers W and the intermediate piece M.

Description

The present invention relates to a wafer manufacturing method used for, for example, a solar cell, and a wafer manufacturing apparatus used directly for carrying out the method.
Specifically, the present invention relates to a wafer manufacturing method and a wafer manufacturing apparatus for slicing a square columnar ingot into a plurality of wafers using a cutting machine.

  Conventionally, as this type of wafer manufacturing method and wafer manufacturing apparatus, a polycrystalline silicon ingot is cut into a rectangular parallelepiped semiconductor block with a band saw type cutting machine or the like, and this semiconductor block is bonded to one surface of a slice base with an adhesive or the like. A plurality of semiconductor blocks are arranged so as to be opposed to the wires of the wire saw device, and these semiconductor blocks are gradually lowered and pressed against the wires, whereby each semiconductor block is simultaneously cut to obtain a plurality of semiconductor wafers. (For example, refer to Patent Document 1).

JP 2006-278701 A (FIG. 4)

  However, in such a conventional wafer manufacturing method and wafer manufacturing apparatus, a rectangular parallelepiped ingot is individually sliced with a wire saw to a thickness of, for example, 300 μm or less. There is a problem that chipping, cracking, chipping, and the like are likely to occur at the corners and ends, and the yield decreases accordingly.

  An object of the present invention is to cope with such problems, to suppress the occurrence of defects such as chipping, cracking and chipping of a wafer, and the occurrence of defects such as chipping, cracking and chipping during wafer separation. The purpose is to further suppress the occurrence of defects such as chipping, cracking, and chipping during wafer separation while the wafers are easily separated from each other.

  In order to achieve such an object, the wafer manufacturing method according to the present invention includes a gap between four flat side surfaces of a plurality of ingots formed in a quadrangular prism shape with an adhesive so that an intermediate plate is sandwiched between them. The ingot bonding step for forming an ingot connection body, and slicing the entire ingot connection body by moving the ingot connection body and the cutting machine relative to each other in a direction crossing the longitudinal direction of the ingot. And slicing the plurality of connecting pieces, and wafer separation for separating the wafer cut from the ingot and the intermediate piece cut from the intermediate plate by reducing the adhesive force of the adhesive in the connecting pieces. And a process.

  In addition to the above-described features, the surface of the intermediate plate is formed such that the surface roughness is smaller than the surface roughness of the side surface of the ingot.

  Further, in addition to the above-described features, the intermediate plate is made of a material having a coefficient of thermal expansion different from that of the ingot, and the adhesive whose adhesive strength is reduced by a temperature change is used.

  In addition, a wafer manufacturing apparatus according to the present invention includes a plurality of ingots that are formed in a quadrangular prism shape and have four flat side surfaces, an intermediate plate member that is sandwiched between the side surfaces of the ingot, and a plurality of the ingots. In the direction crossing the longitudinal direction of the ingot relative to the ingot connecting body, the adhesive forming the ingot connecting body by connecting the side surfaces and the surfaces of the plurality of intermediate plate members without gaps. A cutting machine that is provided so as to move and slices the entire ingot connecting body to cut out a plurality of connecting pieces, the cutting machine serving as the connecting pieces, a wafer cut out from the ingot, and the intermediate plate member The intermediate piece cut out from is cut out in a state of being bonded to each other with the adhesive.

  Further, in addition to the above-described features, the intermediate plate is made of a material that is substantially the same as or close to the hardness of the ingot.

In the wafer manufacturing method according to the present invention having the above-described features, the flat four side surfaces of a plurality of ingots formed in a quadrangular prism shape are bonded to each other with an adhesive so that an intermediate plate is sandwiched therebetween. The ingot connecting body is formed, and the ingot connecting body and the cutting machine are moved relative to each other in a direction crossing the longitudinal direction of the ingot, and the entire ingot connecting body is sliced to form a plurality of connecting pieces from the ingot. Since the wafer to be cut and the intermediate piece cut from the intermediate plate are cut out in a state of being bonded to each other, vibration from the cutting machine is difficult to be transmitted to the corners and ends of each wafer, and then the adhesive is bonded to the connecting piece. By reducing the force, the wafer and the intermediate piece are separated, so the occurrence of defects such as chipping, cracking and chipping of the wafer is suppressed. Door can be.
As a result, high-quality wafers free from defects such as chipping, cracking, and chipping can be obtained in a large amount at a lower cost than conventional wafer manufacturing methods in which rectangular parallelepiped ingots are individually sliced, and yield can be improved. it can. Thereby, it is extremely suitable for the production of solar cell elements that require high quality and low cost.

Further, when the surface of the intermediate plate is formed so that the respective surface roughness is smaller than the surface roughness of the side surface of the ingot, the intermediate plate material has an adhesive strength higher than the adhesive strength between the side surface of the ingot and the adhesive. Because the adhesive strength between the surface and the adhesive is low, when separating the sliced wafer and the intermediate piece, the adhesive peels off from the surface of the intermediate piece, and no excessive force is applied to the corners and edges of each wafer. Therefore, it is possible to suppress the occurrence of defects such as chipping, cracking and chipping during wafer separation.
As a result, the productivity is excellent and the yield can be further improved.

Furthermore, when the intermediate plate material is made of a material having a coefficient of thermal expansion different from that of the ingot, and the adhesive is one whose adhesive strength decreases due to a temperature change, the sliced connecting piece is changed in temperature. The adhesive strength of the adhesive decreases, and at the same time, the wafer and the intermediate piece are smoothly peeled off due to the deformation due to the difference in thermal expansion coefficient between the wafer and the intermediate piece due to the temperature change. It is possible to further suppress the occurrence of defects such as chipping, cracking and chipping during separation.
As a result, the productivity is excellent and the yield can be further improved.
Further, when a glass intermediate plate is used for the silicon ingot, the intermediate plate can be manufactured at a low cost, so that the cutting cost can be reduced.

In addition, the wafer manufacturing apparatus according to the present invention is configured such that a plurality of flat side surfaces of a plurality of ingots formed in a quadrangular prism shape are bonded to each other with an adhesive so that an intermediate plate is sandwiched between them, and an ingot connection is made. The wafer is cut out from the ingot as a plurality of connecting pieces by slicing the whole ingot connecting body by moving the ingot connecting body and the cutting machine relatively in a direction intersecting the longitudinal direction of the ingot. And the intermediate piece cut out from the intermediate plate are cut out in a state where they are adhered to each other, so that vibrations from the cutting machine are difficult to be transmitted to the corners and edges of each wafer. The occurrence of defects such as can be suppressed.
As a result, high-quality wafers free from defects such as chipping, cracking, and chipping can be obtained in a large amount at a lower cost than conventional wafer manufacturing apparatuses that individually slice rectangular parallelepiped ingots, and yield can be improved. it can. Thereby, it is extremely suitable for the production of solar cell elements that require high quality and low cost.

Furthermore, when the intermediate plate material is made of a material that is approximately the same as or close to the hardness of the ingot, when slicing the ingot, the intermediate plate material, and the adhesive with a cutting machine, the cutting resistance of the ingot and the intermediate plate material is small. It is possible to further suppress the occurrence of defects such as wafer chipping, cracking and chipping during slicing.
As a result, the productivity is excellent and the yield can be further improved.
Further, when a glass intermediate plate is used for the silicon ingot, the intermediate plate can be manufactured at a low cost, so that the cutting cost can be reduced.

It is explanatory drawing which shows an ingot adhesion process in the wafer manufacturing method which concerns on embodiment of this invention, and has shown in order of process to (a)-(i). It is a perspective view which shows the whole structure of a slice process and a wafer manufacturing apparatus. It is explanatory drawing which shows a wafer separation process, (a) shows before wafer separation, (b) has shown after wafer separation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the wafer manufacturing method according to the embodiment of the present invention, as shown in FIGS. 1 to 3, four flat side surfaces 1 a of a plurality of ingots 1 formed in a quadrangular prism shape are arranged with an intermediate plate 2 between them. The ingot bonding step for forming the ingot connecting body B by adhering without any gap with the adhesive 3 so as to be sandwiched, and the ingot connecting body B and the cutting machine S are moved relative to each other in a direction crossing the longitudinal direction of the ingot 1. Thus, the slicing step of slicing the entire ingot connector B together to cut out a plurality of connecting pieces B1, and the wafer W cut out from the ingot 1 by reducing the adhesive force of the adhesive 3 in the connecting pieces B1 And a wafer separation step for separating the intermediate piece M from the intermediate plate 2.

  As shown in FIG. 2, a wafer manufacturing apparatus A that is directly used for carrying out such a wafer manufacturing method includes a plurality of ingots 1 that are formed in a quadrangular prism shape and have four flat side surfaces 1a, and a side surface 1a of the ingot 1. The intermediate plate member 2 provided so as to be sandwiched between them, the side surface 1a of the plurality of ingots 1 and the surface 2a of the plurality of intermediate plate members 2 are connected so as to be joined to each other without a gap, thereby forming an ingot connector B The cutting machine which is provided so that it may move to the direction which cross | intersects the longitudinal direction of the ingot 1 with the agent 3 and the ingot coupling body B, slices the whole ingot coupling body B together, and cuts out several coupling piece B1 S.

The ingot 1 is formed in a quadrangular prism shape with a material suitable for manufacturing, for example, a solar cell, such as single crystal silicon, polycrystalline silicon, microcrystalline silicon, amorphous silicon, and other materials, and four flats on the outer periphery thereof. The side surfaces 1a are arranged and formed in parallel.
In the ingot bonding step, as shown in FIGS. 1A to 1I, for example, the side surfaces 1a of the ingots 1 are joined to the side surfaces 1a of the adjacent ingots 1 without gaps. The horizontal direction (X direction) and the vertical direction (Y direction) are arranged so that their longitudinal directions (axial directions) are parallel to each other, and are stacked in multiple layers.

The intermediate plate member 2 is preferably made of a material that is approximately the same as or close to the hardness of the ingot 1.
Further, the intermediate plate member 2 is formed such that both the front and back surfaces 2a thereof are smoothly formed with a surface roughness smaller than the surface roughness of the side surface 1a of the ingot 1, whereby the surface 2a of the intermediate plate member 2 and an adhesive 3 to be described later are formed. The adhesive strength is preferably lower than the adhesive strength between the side surface 1 a of the ingot 1 and the adhesive 3.
The intermediate plate 2 is formed of a material having a coefficient of thermal expansion different from that of the ingot 1 and is subjected to temperature change (heating or cooling) in a state where the ingot 1 and the intermediate plate 2 are bonded to each other. It is preferable that the peeling force be generated between the two due to the difference in deformation amount of the plate member 2.
As a specific example of the intermediate plate member 2, when the ingot 1 is formed of silicon, it is preferable to use a glass plate, particularly blue plate glass that can be easily distinguished from silicon, as the intermediate plate member 2.

It is preferable that the adhesive 3 has a certain degree of adhesive strength at the time of slicing by the cutting machine S to be described later, and is softened by a temperature change (heating or cooling) after slicing to reduce the adhesive force.
As a specific example, an epoxy resin two-component mixed adhesive or other adhesive is used, and a plurality of ingots 1 arranged in the horizontal direction and the vertical direction are sandwiched between the side surface 1a and the side surface 1a. By bonding the front and back surfaces 2a of the plate 2 to each other, the plurality of ingots 1 are connected in a single block to form the ingot connector B.

A fixing plate 4 for preventing the cutting start portion from being broken by the cutting machine S is bonded to one end surface of the ingot connector B facing the cutting machine S, which will be described later, with an adhesive 3, and the cutting end portion is connected to the other end surface. It is preferable that a backing plate (slice base) 5 for preventing loss of the adhesive is bonded with the adhesive 3 and the ingot connector B is sandwiched between the fixing plate 4 and the backing plate 5.
The fixing plate 4 and the contact plate 5 are also preferably formed of, for example, a glass plate, like the intermediate plate 3.
Furthermore, at least in the contact plate 5, the adhesive surface 5a facing the end surface of the ingot connector B is roughened by, for example, sandblasting to increase its surface roughness, thereby increasing the intermediate plate material 2 and It is preferable that the adhesive strength is higher than the adhesive strength to make it difficult to peel off.

For example, as shown in FIG. 2, the cutting machine S moves in the width direction intersecting with the longitudinal direction (axial direction) of the ingot 1 relative to the ingot connected body B in the slicing process. That is, it is a slicing machine that slices the ingot 1, the intermediate plate 2 and the adhesive 3 together.
A plurality of connecting pieces B1 are cut out by slicing the whole ingot connecting body B together by the cutting machine S, and these connecting pieces B1 are cut out from the plurality of wafers W cut out from each ingot 1 and the intermediate plate material 2. A plurality of intermediate pieces M are bonded with an adhesive 3.
As a specific example of the cutting machine S, a multi-wire saw, a multi-band saw, an inner peripheral cutting machine or the like is used.
It is preferable to use a multi-wire saw so that a large number of thin wafers can be cut out from each ingot 1.

  In the wafer separation process, for example, as shown in FIGS. 3A and 3B, the connecting piece B1 sliced by the cutting machine S is subjected to temperature change (heating or cooling), so that the adhesive 3 is softened and has an adhesive force. And a peeling force is generated between each wafer W made of a material having a different coefficient of thermal expansion and each intermediate piece M, so that each of the intermediate pieces M having a lower adhesive strength than each wafer W and the adhesive 3 It is preferable to separate from between the surface and the adhesive 3.

Moreover, it is preferable that an adhesive peeling process is included as a post process of a wafer separation process as needed.
The adhesive stripping step is a step of stripping and removing the adhesive 3 remaining on the outer periphery of each wafer W after each wafer W and each intermediate piece M are separated. As a specific example, For example, treatment using high-temperature water or other chemical treatment can be considered.

  According to such a wafer manufacturing method and wafer manufacturing apparatus A, when the wafer W is cut out from the ingot connector B, the corners and ends of each wafer W are sliced together with the intermediate piece M adhered thereto. Therefore, the vibration from the cutting machine S is hardly transmitted to the corners and ends of each wafer W, thereby suppressing the occurrence of defects such as chipping, cracking and chipping of the wafer W during slicing.

In particular, when the intermediate plate 2 is made of a material that is substantially the same as or close to the hardness of the ingot 1, when the ingot 1, the intermediate plate 2, and the adhesive 3 are sliced together by the cutting machine S, the ingot 1 and the intermediate plate 2 are cut. Resistance is small.
Thereby, it is possible to further suppress the occurrence of defects such as chipping, cracking and chipping of the wafer W during slicing.

Further, between the side surfaces 1a of the adjacent ingots 1, an intermediate plate 2 formed of a material having a surface roughness smaller than the surface roughness of the side surface 1a of the ingot 1 and having a coefficient of thermal expansion different from that of the ingot 1 is bonded. Adhering with the agent 3 facilitates the separation of the wafers W for the following reasons, and can suppress the occurrence of defects such as chipping, cracking and chipping of the wafers W during the separation.
That is, when the side surfaces 1a of the ingots 1 are directly bonded to each other only with the adhesive 3 without sandwiching the intermediate plate material 2, the adhesive strength between the side surface 1a of each ingot 1 and the adhesive 3 is increased, so that the slices were sliced. When the wafers W are separated from each other, an excessive force is applied to the corners and ends of the wafers W, and chipping, cracking, and chipping are likely to occur.
On the other hand, in the embodiment of the present invention, since the adhesive strength between the surface 2a of each intermediate plate 2 and the adhesive 3 is lower than the adhesive strength between the side surface 1a of each ingot 1 and the adhesive 3, the sliced wafer When the W and the intermediate piece M are separated, the adhesive 3 is peeled off from the surface 2a of the intermediate piece M, and the wafer W can be separated without applying excessive force to the corners and ends of each wafer W. Separation of each other is easy, and the occurrence of defects such as chipping, cracking and chipping of the wafer W during separation can be suppressed.
Next, an embodiment of the present invention will be described with reference to the drawings.

  In this embodiment, as shown in FIGS. 1, 2 and 3A and 3B, the fixing plate 4 and the contact plate 5 are bonded to both ends of the ingot connecting body B in the ingot bonding process, and the cutting process is performed in the slicing process. As the machine S, the multi-wire saw and the ingot connecting body B are relatively moved so that the entire ingot connecting body B is sliced together, and the wafer W and the intermediate piece M are bonded with the adhesive 3. The piece B1 is cut out, and in the wafer separation step, the connecting piece B1 is immersed in the fluid F in the liquid tank C and heated.

In the example shown in FIGS. 1 (a) to (i), the ingots 1 are first aligned in the horizontal direction on the adhesive surface 5 a of the backing plate 5, and the short intermediate plate 2 is sandwiched between them, and then A plurality of rows are arranged so as to sandwich the long intermediate plate 2 in the vertical direction.
In the illustrated example, four rows of ingots 1 are arranged in the horizontal direction and the vertical direction, respectively.
Although not shown as another example, the ingots 1 can be arranged in three or less rows or five or more rows in the horizontal direction and the vertical direction, or in different rows in the horizontal direction and the vertical direction.

In the example shown in FIG. 2, slicing is started from the fixed plate 4 side by moving the ingot connector B up and down with respect to the wire S <b> 1 of the multi-wire saw serving as the cutting machine S, and then the adhesive plate 5 is bonded. Control is performed so as to end the slicing of the ingot connector B when it is partially cut across the surface 5a.
Furthermore, after slicing the ingot connector B with the multi-wire saw serving as the cutting machine S, all the sliced connecting pieces B1 are removed by peeling off the backing plate 5 from the sliced ingot connector B. To be separated.
Further, although not shown as another example, it is possible to move the wire S1 of the multi-wire saw serving as the cutting machine S up and down with respect to the ingot connector B.

In the example shown in FIGS. 3A and 3B, as shown in FIG. 3A, the sliced connecting piece B1 is used as the fluid F stored in the liquid tank C, for example, high-temperature water at a predetermined temperature. When the connecting piece B1 is heated to a predetermined temperature, the adhesive 3 interposed between each wafer W and each intermediate piece M is softened and the adhesive strength is lowered, thereby reducing the bonding strength shown in FIG. As shown in (b), each wafer W and each intermediate piece M are separated.
Although not shown as another example, it is possible to reduce the adhesive strength of the adhesive 3 by heating the connecting piece B1 with the fluid F stored in the liquid tank C.

According to the wafer manufacturing method and the wafer manufacturing apparatus A according to the embodiment of the present invention, the adhesive strength of the adhesive 3 can be obtained simply by immersing the sliced connecting piece B1 in the fluid F in the liquid tank C and heating it. At the same time, the wafer W and the intermediate piece M are smoothly peeled off due to the deformation due to the difference in thermal expansion coefficient between the wafer W and the intermediate piece M due to the temperature change.
Thereby, separation of the wafers W can be further facilitated, and the occurrence of defects such as chipping, cracking, and chipping during the separation of the wafers can be further suppressed.

Further, since the fixing plate 5 is sliced at the beginning of the cutting of the ingot connector B by the cutting machine S, the cutting resistance and the cutting position are stabilized and each ingot 1 is cut smoothly.
Thereby, there is an advantage that warpage and thickness variation of each cut out wafer W can be prevented.

Furthermore, when the intermediate plate member 2 is used in which both the front and back surfaces 2a are smoother than the surface roughness of the side surface 1a of the ingot 1, the surface of each intermediate piece M in the wafer separation step is used. Although the adhesive 3 is peeled off from 2a, the adhesive 3 may continue to adhere to the outer periphery of each wafer W and remain.
In this case, in the adhesive peeling process that is a subsequent process of the wafer separation process, the adhesive 3 that remains attached to the outer periphery of each wafer W is peeled off and removed by high-temperature water or chemical treatment.

In the previous embodiment, the multi-wire saw was relatively moved as the ingot connector B with the fixed plate 4 and the backing plate 5 bonded to both ends and the cutting machine S, but the present invention is not limited to this. Either one or both of the fixing plate 4 and the contact plate 5 may not be bonded to the connector B, and a multi-band saw, an inner peripheral blade type cutting machine, or the like may be used as the cutting machine S.
Furthermore, although connecting piece B1 was immersed and heated in the fluid F in the liquid tank C, it is not limited to this, You may reduce the adhesive strength of the adhesive agent 3 by another method.

DESCRIPTION OF SYMBOLS 1 Ingot 1a Side surface 2 Intermediate board 2a Surface 3 Adhesive B Ingot connection body B1 Connection piece M Intermediate piece S Cutting machine W Wafer

Claims (5)

Adhering the flat four side surfaces (1a) of a plurality of ingots (1) formed in a quadrangular prism shape with an adhesive (3) so that the intermediate plate (2) is sandwiched between them, An ingot bonding step for forming an ingot connector (B);
The ingot connector (B) and the cutting machine (S) are relatively moved in a direction intersecting the longitudinal direction of the ingot (1), thereby slicing the entire ingot connector (B). A slicing step of cutting out the connecting piece (B1);
By reducing the adhesive force of the adhesive (3) in the connecting piece (B1), the wafer (W) cut out from the ingot (1) and the intermediate piece (M) cut out from the intermediate plate (2) And a wafer separation process for separating the wafer.   The surface (2a) of the intermediate plate (2) is formed so that each surface roughness is smaller than the surface roughness of the side surface (1a) of the ingot (1). Wafer manufacturing method.   The intermediate plate (2) is made of a material having a coefficient of thermal expansion different from that of the ingot (1), and the adhesive (3) is used whose adhesive strength decreases with temperature change. Or the wafer manufacturing method of 2. A plurality of ingots (1) formed in a quadrangular prism shape and having four flat side surfaces (1a), and an intermediate plate (2) provided so as to be sandwiched between the side surfaces (1a) of the ingot (1); ,
Adhesive that connects the side surfaces (1a) of the plurality of ingots (1) and the surfaces (2a) of the plurality of intermediate plate members (2) so as to be joined to each other without gaps to form an ingot connector (B). (3) and
It is provided so as to move in a direction crossing the longitudinal direction of the ingot (1) relative to the ingot connector (B), and the entire ingot connector (B) is sliced to form a plurality of connecting pieces (B1 A cutting machine (S) for cutting out
In the cutting machine (S), a wafer (W) cut out from the ingot (1) and an intermediate piece (M) cut out from the intermediate plate (3) are used as the connecting piece (B1). 3. A wafer manufacturing apparatus, wherein the wafer is cut out in a state of being bonded to each other in 3).   The wafer manufacturing apparatus according to claim 4, wherein the intermediate plate (2) is made of a material that is substantially the same as or close to the hardness of the ingot (1).

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