Wafer cleavage separation device and cleavage separation method

Abstract

The present invention provides a wafer cleavage separation apparatus and a cleavage separation method capable of simply and surely manufacturing a high-quality semiconductor crystal wafer. 【Solution means】A cleavage separation apparatus for a SiC wafer, which is a semiconductor crystal wafer, is an apparatus that separates a wafer W in a slice shape along a cutting guide line G from a state where a cutting guide line G is formed on a planned cutting surface by scanning a condensing point where a laser beam having a transmissive wavelength is condensed on a SiC ingot Ig, which is a cylindrical semiconductor crystal ingot, and includes an ingot fixing portion 1, an attachment plate 2, and a tensile stress generation portion 3.

Description

Technical Field

[0001] The present invention relates to a wafer cleavage separation apparatus and a cleavage separation method for separating a wafer into slices along a cleavage guide line formed by scanning a condensing point where a laser beam having a wavelength permeable to a planned cleavage surface of a cylindrical semiconductor crystal ingot is condensed.

Background Art

[0002] Conventionally, as a cleavage separation apparatus for this type of semiconductor crystal wafer, a pulsed laser beam having a wavelength that penetrates a semiconductor crystal ingot is irradiated, and the condensing point of the laser beam is positioned at a predetermined depth position in the semiconductor crystal ingot. Then, a separation layer forming step of forming a separation layer in the semiconductor crystal ingot by relatively moving the semiconductor crystal ingot and the condensing point along a predetermined direction, and a separation step of separating a wafer from the semiconductor crystal ingot starting from the separation layer are provided. In the separation step, the entire end surface of the semiconductor crystal ingot is sucked and held by the holding surface of a suction head, and a wedge is driven into a plurality of positions along the circumferential direction of the semiconductor crystal ingot (not only at one position on the side surface) at the height position of the separation layer with respect to the side surface of the semiconductor crystal ingot.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in such a conventional method for cleaving and separating a semiconductor crystal wafer, as described in Patent Document 1 above, "The applicant has confirmed in experiments that when an external force is applied all at once, undesirable cracks occur." Even while following a complex procedure such as driving a plurality of wedges along the circumferential direction of the semiconductor crystal ingot, it is adjacent to undesirable cracks, and there is a desire to establish a method for performing cleavage separation simply and reliably.

[0005] In view of the above circumstances, an object of the present invention is to provide a wafer cleavage separation apparatus and a cleavage separation method capable of simply and reliably manufacturing a high-quality semiconductor crystal wafer.

Means for Solving the Problems

[0006] The wafer cleavage separation apparatus of the first invention is a wafer cleavage separation apparatus for separating a wafer in a slice shape along a cutting guideline formed by scanning a condensing point of a laser beam having a wavelength with permeability on a planned cutting surface of a cylindrical semiconductor crystal ingot, an ingot fixing portion for fixing the semiconductor crystal ingot, a pasting plate that covers the entire end face on the wafer side and pastes the end face, a tensile stress generating portion that generates a tensile stress in the pasting plate by applying a tensile load in a direction separating the central portion of the pasting plate from the semiconductor crystal ingot and is characterized by comprising.

[0007] According to the wafer cleavage separation device of the first invention, in a state where the entire end face on the wafer side is covered by the attachment plate and attached to the attachment plate, the tensile stress generating portion applies a tensile load in a direction to separate the central portion of the attachment plate from the semiconductor crystal ingot, thereby generating tensile stress in the attachment plate (at this stage, the attachment plate itself does not deform). Such tensile stress can act as a tensile stress to separate the wear from the central portion of the planned cutting surface through the end face on the wafer side attached to the attachment plate.

[0008] Therefore, without generating unfavorable cracks by promoting separation from the side surface of the semiconductor crystal ingot as in the prior art, cleavage separation can be performed simply and reliably.

[0009] Thus, according to the wafer cleavage separation device of the first invention, high-quality semiconductor crystal wafers can be manufactured simply and reliably.

[0010] The wafer cleavage separation device of the second invention is, in the first invention, the tensile stress generating portion a base plate attached to a part or all of the periphery of the attachment plate via a spacer, and a pulling bolt having one end connected to the central portion of the attachment plate through a through hole formed in the central portion of the base plate and is characterized by having.

[0011] According to the wafer cleavage separation device of the second invention, by configuring the tensile stress generating portion with a base plate attached to the periphery of the attachment plate via a spacer and a pulling bolt having one end connected to the central portion of the attachment plate through a through hole formed in the central portion of the base plate, a tensile load that pulls the central portion of the attachment plate in a direction to separate it from the semiconductor crystal ingot can be actually applied, and tensile stress can be generated in the attachment plate.

[0012] Thus, according to the wafer cleavage and separation device of the second invention, high-quality semiconductor crystal wafers can be simply and reliably actually manufactured.

[0013] The wafer cleavage and separation device of the third invention is as follows in the second invention. The spacer is attached to face the peripheries of the opposite sides, and the through hole and the pull bolt are provided to be aligned with the center of the base plate parallel to the opposite sides.

[0014] According to the wafer cleavage and separation device of the third invention, by aligning the pull bolt with the center of the base plate parallel to the spacer attached to face the peripheries of the opposite sides, the tensile stress of the attachment plate and the tensile stress at the planned cutting surface are configured to propagate from the alignment direction through the end face on the wafer side attached to the attachment plate.

[0015] Thereby, taking into account the propagation of the tensile stress, cleavage and separation can be performed more simply and reliably.

[0016] Thus, according to the wafer cleavage and separation device of the third invention, high-quality semiconductor crystal wafers can be manufactured more simply and reliably.

[0017] The wafer cleavage and separation device of the fourth invention is as follows in the third invention. The attachment plate is characterized in that continuous concave grooves are formed on the wafer side.

[0018] According to the wafer cleavage and separation device of the fourth invention, the attachment plate forms continuous concave grooves on the surface on the wafer side (the surface to which the end face on the wafer side of the semiconductor crystal ingot is attached), making it possible to easily separate the separated wafers from the attachment plate.

[0019] Thus, according to the wafer cleavage and separation device of the fourth invention, high-quality semiconductor crystal wafers can be simply and reliably manufactured while improving workability.

[0020] The wafer cleavage and separation device of the fifth invention, in the fourth invention, The concave groove is characterized in that it is continuously formed in the direction of the opposing spacers.

[0021] According to the wafer cleavage and separation device of the fifth invention, by continuously forming the concave groove in the direction of the opposing spacers, the bonding plate will not be curved and deformed by the tensile load, and a predetermined tensile load can be applied in the direction of separating the central portion of the bonding plate from the semiconductor crystal ingot, so that tensile stress can be generated in the bonding plate.

[0022] The wafer cleavage and separation method of the sixth invention is A wafer cleavage and separation method for separating a wafer in a slice shape along a cutting guideline formed by scanning a condensing point where a laser beam having a wavelength with permeability is condensed on a planned cutting surface of a cylindrical semiconductor crystal ingot, An ingot fixing step of fixing the semiconductor crystal ingot on which the cutting guideline is formed, An attaching step of attaching the entire end face on the wafer side to an attaching plate, A tensile stress generating step of generating tensile stress in the attaching plate by applying a tensile load in the direction of separating the central portion of the attaching plate from the semiconductor crystal ingot characterized by comprising.

[0023] According to the wafer cleavage and separation method of the sixth invention, with the entire end face on the wafer side attached to the attaching plate by the attaching plate, in the tensile stress generating step, by applying a tensile load in the direction of separating the central portion of the attaching plate from the semiconductor crystal ingot, (at this stage, the attaching plate itself does not deform) tensile stress is generated in the attaching plate. Such tensile stress can act as a tensile stress for separating the wear from the central portion of the planned cutting surface through the end face on the wafer side attached to the attaching plate.

[0024] Therefore, it is possible to perform cleavage separation simply and reliably without causing unfavorable cracks due to promoting separation from the side surface of a conventional semiconductor crystal ingot.

[0025] Thus, according to the wafer cleavage separation method of the sixth invention, a high-quality semiconductor crystal wafer can be manufactured simply and reliably.

[0026] The wafer cleavage separation method of the seventh invention is the same as that of the sixth invention, wherein the tensile stress generation step is characterized in that a tensile load is applied in a direction separating the entire radial direction including the central portion of the attachment plate from the semiconductor crystal ingot. According to the wafer cleavage separation method of the seventh invention, by applying a tensile load to the entire radial direction including the central portion of the attachment plate, the tensile stress of the attachment plate and the tensile stress at the planned cutting surface can be generated at the radial starting point through the end surface on the wafer side attached to the attachment plate.

[0027] Thereby, taking into account the propagation of the tensile stress, cleavage separation can be performed more simply and reliably.

[0028] Thus, according to the wafer cleavage separation method of the seventh invention, a high-quality semiconductor crystal wafer can be manufactured more simply and reliably.

[0029] The wafer cleavage separation method of the eighth invention is the same as that of the seventh invention, and is characterized by comprising an external force step of applying an external force to the end portion in the radial direction where the tensile load is applied.

[0030] According to the wafer cleavage separation method of the eighth invention, by applying an external force to the end portion in the radial direction where the tensile load is applied, a starting point serving as a trigger for separation is formed, and separation can be propagated in the radial direction in which the tensile stress acts from such a starting point of separation.

[0031] Accordingly, by utilizing the propagation of separation due to tensile stress, cleavage separation can be performed more simply and reliably.

[0032] Thus, according to the wafer cleavage separation method of the eighth invention, high-quality semiconductor crystal wafers can be manufactured more simply and reliably.

Brief Description of the Drawings

[0033]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Embodiments for Carrying Out the Invention

[0034] As shown in FIG. 1, in the present embodiment, a cleavage separation apparatus for a SiC wafer, which is a semiconductor crystal wafer, forms a cutting guide line G on a planned cutting surface by scanning a condensing point where a laser beam having a transmissive wavelength is condensed on a SiC ingot Ig, which is a cylindrical semiconductor crystal ingot, and then separates the wafer W in a slice shape along the cutting guide line G. The apparatus includes an ingot fixing portion 1, an attachment plate 2, and a tensile stress generating portion 3.

[0035] The ingot fixing portion 1 is configured to fix the SiC ingot Ig. Specifically, it is composed of a metallic plate 11 that attaches the end face of the SiC ingot Ig via a joining means such as an adhesive or a double-sided tape, and a base plate 12 integrally formed with the plate 11. Note that the ingot fixing portion 1 is not limited to the plate 11 and the base plate 12 as long as it is configured to fix the SiC ingot Ig, and existing ingot fixing means may be used.

[0036] The attachment plate 2 is an attachment plate that covers the entire end face on the wafer W side separated from the SiC ingot Ig and attaches the end face via a joining means such as an adhesive or a double-sided tape. Note that the attachment plate 2 is basically the same as the plate 11.

[0037] Here, it is preferable that at least the attachment plate 2 is formed with a concave groove 20 continuous with the end face side of the wafer W (similarly, it is preferable that a concave groove is also formed in the SiC ingot Ig of the plate 11).

[0038] The tensile stress generating portion 3 is a means for generating a tensile stress in the attachment plate 2 by applying a tensile load in a direction to separate the central portion of the attachment plate from the SiC ingot Ig.

[0039] Specifically, the tensile stress generating portion 3 includes a spacer 30 at a part or all of the periphery of the attachment plate 2, a base plate 31 attached via the spacer 30, and a pulling bolt 32 whose one end is connected to the central portion of the attachment plate 2 via a through hole formed in the central portion of the base plate 31.

[0040] Here, in this embodiment, one end of the pulling bolt 32 is screwed into the screw hole of the attachment plate 2 through the through hole, and by rotating the pulling bolt 32, a tensile load is applied to the attachment plate 2. Alternatively, a screw hole may be provided in the central portion of the base plate 31 (instead of the through hole), the pulling bolt 32 may be screwed in, and one end may be fixed to the central portion of the attachment plate 2, and by rotating the pulling bolt 32, a tensile load may be applied to the attachment plate 2.

[0041] The spacer 30 is preferably attached so as to face the peripheries of the opposing sides, and the pulling bolt 32 is provided aligned with the center of the base plate 12 parallel to the opposing sides of the spacer 30. Note that the spacer 30 may be, for example, a double-sided tape of a predetermined thickness or a film-like intervening material.

[0042] At this time, the concave groove 20 is preferably arranged so as to be continuous in the direction of the opposing spacer 30 (so as to reciprocate the opposing spacer 30).

[0043] The SiC wafer cleavage separation device configured as described above is used as an SiC wafer cleavage separation method as follows.

[0044] First, a cutting guide line G is formed by scanning a condensing point where a laser beam having a wavelength with permeability is condensed on the planned cutting surface of the SiC ingot Ig (cutting guide line forming step).

[0045] Next, the SiC ingot Ig on which the cutting guideline G is formed is fixed by attaching the end face on the side opposite to the wafer W to be separated to the plate 11 via a joining means (ingot fixing step).

[0046] Next, the end face of the SiC ingot Ig on the wafer W side is attached to the attachment plate 2. At this time, the adhesive is applied only to the convex portions of the concave grooves 20 formed in the attachment plate 2, and the end face of the SiC ingot Ig is attached to the surface on which the applied concave grooves 20 are formed.

[0047] Next, on the upper surface of the attachment plate 2 (the surface opposite to the attachment surface of the SiC ingot Ig), the spacers 30 are arranged facing each other at the edges of the opposing sides parallel to the alignment direction of the screw holes of the pull bolts 32 (the same as the 'radial direction' of the present invention).

[0048] Then, the base plate 12 is arranged on the attachment plate 2 on which the spacers 30 are arranged so that the spacers 30 facing the through holes of the pull bolts 32 are parallel.

[0049] At this time, the positions of the through holes of the base plate 12 and the screw holes of the attachment plate 2 coincide with each other in the vertical direction. A plurality of bolts 32 are inserted through the through holes of the base plate 12 and screwed into the screw holes of the attachment plate 2, and are rotated via a torque wrench or the like until a predetermined tightening torque is reached.

[0050] Thereby, as schematically shown by the arrow in FIG. 2A, a tensile stress is generated in the attachment plate 2 by applying a tensile load in a direction separating the central portion of the attachment plate 2 from the SiC ingot Ig (tensile load application step) (tensile stress generation step).

[0051] Such a tensile load acts on each part of the attachment plate 2 into which a plurality of aligned bolts 32 are screwed, as schematically shown in Fig. 2B, (in this state, the attachment plate 2 itself does not deform), and generates tensile stress around each screw hole of the attachment plate 2.

[0052] Then, as shown in Fig. 3A, when the plurality of pull bolts 32 are tightened to a predetermined tightening torque, the tensile stress generated in the attachment plate 2 as shown in Fig. 3B is accumulated (even in this state, the attachment plate 2 itself does not deform) from each screw hole toward the spacer 30.

[0053] In this state, as shown in Figs. 4A and 4B, an external force is applied to the radial end where the tensile load acts (for example, in addition to hitting with a hammer, impact such as inserting an impact needle into the cutting guideline G. External force step), and the attachment plate 2 is displaced from the tensile stress point of the pull bolt 32 on the side where the external force is applied, and this is sequentially propagated to the tensile stress points of the adjacent pull bolts 32, so that the attachment plate 2 is displaced from the external force application point also in the alignment direction of the pull bolts 32, and the wafer W is separated (wafer separation step).

[0054] In this way, by applying an external force to the end in the alignment direction (radial direction) where the tensile load acts, a starting point serving as a trigger for separation is formed, and separation can be propagated in the radial direction where tensile stress acts from such a starting point of separation. Thereby, cleavage separation can be performed more simply and reliably by utilizing the propagation of separation by tensile stress.

[0055] Furthermore, at this time, the deformation of the wafer W integrated with the attachment plate 2 is limited to the gap range between the base plate 31 defined by the thickness of the spacer 30. That is, since the attachment plate 2 comes into contact with the base plate 31 and the deformation stops, the bending deformation of the wafer W integrated with the attachment plate 2 is limited to the gap width, and breakage and cracking of the wafer can be prevented.

[0056] The above is the detail of the cleavage separation method of the SiC wafer of this embodiment. As described in detail above, the SiC ingot can be accurately separated into slice-shaped SiC wafers, and high-quality SiC wafers can be manufactured simply and reliably.

[0057] In addition, in the cleavage method of the SiC wafer of this embodiment, after the above-described series of processes, a chemical mechanical polishing (CMP) process or a wafer cleaning process may be performed as necessary.

[0058] Also, in this embodiment, the case of cleaving and separating the SiC wafer from the SiC ingot has been described as the cleavage separation apparatus and method for the semiconductor crystal wafer. However, the semiconductor crystal is not limited to SiC, and may be gallium arsenide, indium phosphide, silicon, or other compound semiconductors.

[0059] Also, in this embodiment, the case of applying an external force to the end portion in the alignment direction (radial direction) has been described. However, the separation propagation by tensile stress may be started without applying an external force by other external means or internal means. As other external means, sound waves (including ultrasonic waves) or thermo-optical means may be adopted, and as internal means, an increase in further tensile stress or the like may be used.

[0060] Furthermore, in this embodiment, the tensile stress generating portion 3 is constituted by the spacer 30, the base plate 31, and the pulling bolt 32. However, the present invention is not limited to this, and any means can be adopted as long as it is a means for applying a predetermined tensile load to the central portion of the attachment plate. Explanation of reference numerals

[0061] 1... ingot fixing portion, 2... attachment plate, 3... tensile stress generating portion, 11... plate, 20... concave groove, 30... spacer, 31... base plate, 32... pulling bolt, G... cutting guideline, Ig... SiC ingot (semiconductor crystal ingot), W... wafer.

Claims

1. A wafer cleavage separation apparatus for separating a wafer into slices along a cutting guideline formed by scanning a focal point of a laser beam having a wavelength that is transparent to a cutting surface of a cylindrical semiconductor crystal ingot, the apparatus comprising: an ingot fixing portion for fixing the semiconductor crystal ingot; an attachment plate for covering the entire end surface on the wafer side and attaching the end surface; a tensile stress generating section that generates a tensile stress in the attachment plate by applying a tensile load to the attachment plate in a direction that separates the attachment plate from the semiconductor crystal ingot; A cleavage separation apparatus comprising:

2. 2. The wafer cleavage and separation apparatus according to claim 1, The tensile stress generating portion is A base plate attached to a part or the whole of a periphery of the attachment plate via a spacer; a tension bolt having one end connected to the center of the attachment plate through a through hole formed in the center of the base plate; A wafer cleavage and separation apparatus comprising:

3. 3. The wafer cleavage and separation apparatus according to claim 2, a spacer attached to the periphery of each of the opposing sides, and the through hole and the pull bolt are aligned in parallel with the opposing sides at the center of the base plate, said spacer being attached to the periphery of each of the opposing sides,

4. 4. The wafer cleavage and separation apparatus according to claim 3, The wafer cleavage separation apparatus is characterized in that the attachment plate has a groove formed thereon that is continuous with the wafer side.

5. 5. The wafer cleavage and separation apparatus according to claim 4, 4. A wafer cleavage separation apparatus, comprising: a first spacer and a second spacer; a second spacer formed on the first spacer;

6. A method for cleaving a wafer, comprising: scanning a focal point of a laser beam having a wavelength that is transparent to a surface to be cut of a cylindrical semiconductor crystal ingot to separate the wafer into slices along a cutting guideline formed by the laser beam, the focal point being scanned along the cutting guideline; an ingot fixing step of fixing the semiconductor crystal ingot on which the cutting guide line is formed; a bonding step of bonding the entire end surface of the wafer side to a bonding plate; a tensile stress generating step of generating a tensile stress in the attachment plate by applying a tensile load to the attachment plate in a direction separating the center portion of the attachment plate from the semiconductor crystal ingot; A method for cleaving and separating a wafer, comprising:

7. 7. The method for cleaving a wafer according to claim 6, further comprising the steps of: The method for cleaving a wafer, wherein the tensile stress generating step applies a tensile load in a direction that separates the entire radial area of ​​the attachment plate, including the center portion, from the semiconductor crystal ingot.

8. 8. The method for cleaving a wafer according to claim 7, further comprising the steps of: A method for cleaving a wafer, comprising the step of applying an external force to the radial end portion to which the tensile load is applied.

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