Wafer cleavage separation device and cleavage separation method

Abstract

The present invention provides a wafer cleavage separation device and a cleavage separation method that are capable of easily and surely manufacturing a high-quality semiconductor crystal wafer. Provided is a wafer cleavage separation device for an SiC wafer, which is a semiconductor crystal wafer, the device separating a wafer W in a slice shape along a cutting guideline G from a state in which the cutting guideline G is formed on a planned cutting surface by scanning an SiC ingot Ig, which is a cylindrical semiconductor crystal ingot, with a condensing point obtained by condensing a laser beam having a transmission wavelength. The cleavage separation device comprises an ingot fixing part 1, a sticking plate 2, and a tensile stress generation part 3.

Description

Wafer Cleavage Separation Device and Cleavage Separation Method

[0001] The present invention relates to a wafer cleavage separation device 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 that is transmissive to a cutting planned surface of a cylindrical semiconductor crystal ingot is condensed.

[0002] Conventionally, as a device for cleavage-separating this type of semiconductor crystal wafer, a pulsed laser beam having a wavelength that penetrates the 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. 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 the wafer from the semiconductor crystal ingot starting from the separation layer. In the separation step, the entire end face of the semiconductor crystal ingot is sucked and held by the holding surface of the 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 location on the side surface) at the height position of the separation layer with respect to the side surface of the semiconductor crystal ingot.

[0003] Japanese Patent Application Laid-Open No. 2023-181727

[0004] However, in such a conventional method for cleavage-separating a semiconductor crystal wafer, as described in the above Patent Document 1, "The applicant has confirmed in experiments that when an external force is applied all at once, undesirable cracks occur." Even while following a complicated 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 demand for establishing 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 device and a cleavage separation method that can simply and reliably manufacture high-quality semiconductor crystal wafers.

[0006] The wafer cleavage separation apparatus of the first invention is a wafer cleavage separation apparatus that separates a wafer into slices along a cutting guideline formed by scanning a focal point created by focusing a laser beam of a transparent wavelength onto the cutting surface of a cylindrical semiconductor crystal ingot, and is characterized by comprising: an ingot fixing part for fixing the semiconductor crystal ingot; a bonding plate that covers the entire end face of the wafer and adheres the end face to it; and a tensile stress generating part that generates tensile stress in the bonding plate by applying a tensile load in a direction that separates the central part of the bonding plate from the semiconductor crystal ingot.

[0007] According to the wafer cleavage and separation apparatus of the first invention, with the entire end face of the wafer side covered by the adhesive plate and the end face attached to the adhesive plate, a tensile load is applied by the tensile stress generating unit in a direction that separates the central part of the adhesive plate from the semiconductor crystal ingot, thereby generating tensile stress in the adhesive plate (the adhesive plate itself does not deform at this stage). This tensile stress can be applied as a tensile stress that separates the wafer from the central part of the cutting surface via the end face of the wafer side attached to the adhesive plate.

[0008] Therefore, cleavage separation can be performed simply and reliably without causing undesirable cracking that occurs when separation is promoted from the side of the semiconductor crystal ingot, as is the case with conventional methods.

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

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

[0011] According to the wafer cleavage separation apparatus of the second invention, the tensile stress generating section is configured with a base plate attached to the periphery of the bonding plate via a spacer, and a tension bolt whose one end is connected to the central part of the bonding plate through a through hole formed in the central part of the base plate. This allows a tensile load to be applied that pulls the central part of the bonding plate away from the semiconductor crystal ingot, thereby generating tensile stress in the bonding plate.

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

[0013] The wafer cleavage separation apparatus of the third invention is characterized in that, in the second invention, the spacer is attached opposite to the periphery of the opposing sides, and the through hole and the tension bolt are arranged in the center of the base plate parallel to the opposing sides.

[0014] According to the wafer cleavage and separation apparatus of the third invention, by aligning the tension bolts in the center of the base plate parallel to the spacers attached opposite to the periphery of the opposing edges, it is possible to configure the apparatus so that the tensile stress of the bonding plate and the tensile stress at the cutting surface via the wafer end face attached to the bonding plate propagate from the alignment direction.

[0015] This allows for simpler and more reliable cleavage separation by taking into account the propagation of tensile stress.

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

[0017] The wafer cleavage separation apparatus of the fourth invention is characterized in that, in the third invention, the adhesive plate has a continuous groove formed on the wafer side.

[0018] According to the wafer cleavage separation apparatus of the fourth invention, the adhesive plate has continuous grooves formed on the wafer-side surface (the surface to which the wafer-side end face of the semiconductor crystal ingot is attached), making it possible to easily separate the separated ware from the adhesive plate.

[0019] Thus, the wafer cleavage separation apparatus of the fourth invention makes it possible to easily and reliably manufacture high-quality semiconductor crystal wafers while improving work efficiency.

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

[0021] According to the wafer cleavage separation apparatus of the fifth invention, the grooves are formed continuously in the direction of the opposing spacers, so that the bonding plate does not bend or deform due to the tensile load, and a predetermined tensile load can be applied in a direction that separates the central part of the bonding plate from the semiconductor crystal ingot, thereby generating tensile stress in the bonding plate.

[0022] The sixth invention is a wafer cleavage separation method, which separates a wafer into slices along a cutting guideline formed by scanning a focal point created by focusing a laser beam of a transparent wavelength onto the cutting surface of a cylindrical semiconductor crystal ingot, and is characterized by comprising: an ingot fixing step of fixing the semiconductor crystal ingot on which the cutting guideline has been formed; a bonding step of bonding the entire end face of the wafer to a bonding plate; and a tensile stress generation step of generating tensile stress in the bonding plate by applying a tensile load in a direction that separates the central part of the bonding plate from the semiconductor crystal ingot.

[0023] According to the wafer cleavage separation method of the sixth invention, with the entire end face of the wafer attached to the attachment plate by the attachment plate, a tensile load is applied in the direction that separates the central part of the attachment plate from the semiconductor crystal ingot during the tensile stress generation step, thereby generating tensile stress in the attachment plate (the attachment plate itself does not deform at this stage). This tensile stress can be applied as a tensile stress that separates the wafer from the central part of the cutting surface via the end face of the wafer attached to the attachment plate.

[0024] Therefore, cleavage separation can be performed simply and reliably without causing undesirable cracking that occurs when separation is promoted from the side of the semiconductor crystal ingot, as is the case with conventional methods.

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

[0026] The wafer cleavage separation method of the seventh invention is characterized in that, in the sixth invention, the tensile stress generation step is performed by applying a tensile load in a direction that separates the entire radial direction, including the central part of the bonding 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 part of the bonding plate, it is possible to configure the device so that tensile stress in the bonding plate and tensile stress at the cutting surface via the wafer end face attached to the bonding plate are generated at a radial starting point.

[0027] This allows for simpler and more reliable cleavage separation by taking into account the propagation of tensile stress.

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

[0029] The wafer cleavage separation method of the eighth invention is characterized in that, in the seventh invention, it comprises an external force step of applying an external force to the radial end to which the tensile load is applied.

[0030] According to the wafer cleavage separation method of the 8th invention, by applying an external force to the radial end to which a tensile load is applied, a starting point that triggers separation can be formed, and the separation can be propagated from this starting point in the radial direction to which tensile stress is applied.

[0031] This allows for simpler and more reliable cleavage separation by utilizing the propagation of separation due to tensile stress.

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

[0033] An explanatory diagram of the SiC wafer (semiconductor crystal wafer) cleavage separation apparatus of this embodiment, viewed from the side. An explanatory diagram of the SiC wafer (semiconductor crystal wafer) cleavage separation apparatus of this embodiment, viewed from above. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1A. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1B. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1A. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1B. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1A. An explanatory diagram showing the details of the SiC wafer (semiconductor crystal wafer) cleavage separation method of this embodiment, corresponding to Figure 1B.

[0034] As shown in Figure 1, in this embodiment, the SiC wafer cleavage separation apparatus is a apparatus that separates a wafer W in slice form along a cutting guideline G formed on the cutting surface by scanning a focal point created by focusing a laser beam of a transparent wavelength onto a cylindrical semiconductor crystal ingot Ig, and comprises an ingot fixing part 1, a bonding plate 2, and a tensile stress generating part 3.

[0035] The ingot fixing section 1 is configured to fix the SiC ingot Ig, and specifically consists of a metallic plate 11 to which the end face of the SiC ingot Ig is attached via bonding means such as adhesive or double-sided tape, and a base plate 12 which is integrally formed with the plate 11. Note that the ingot fixing section 1 is not limited to the plate 11 and base plate 12, but may be any existing ingot fixing means as long as it is configured to fix the SiC ingot Ig.

[0036] The attachment plate 2 covers the entire end face on the wafer W side that separates from the SiC ingot Ig, and is attached to the end face via bonding means such as adhesive or double-sided tape. Note that the attachment plate 2 is basically identical to plate 11.

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

[0038] The tensile stress generating unit 3 is a means for generating tensile stress in the adhesive plate 2 by applying a tensile load in a direction that separates the central part of the adhesive plate from the SiC ingot Ig.

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

[0040] In this embodiment, the tension bolt 32 is applied to the adhesive plate 2 by rotating it, with one end screwed into a threaded hole in the adhesive plate 2 through a through hole. Alternatively, a threaded hole (instead of a through hole) may be provided in the center of the base plate 31, the tension bolt 32 may be screwed into it, and one end fixed to the center of the adhesive plate 2, thereby applying a tensile load to the adhesive plate 2 by rotating the tension bolt 32.

[0041] The spacer 30 is preferably attached facing the peripheries of the opposing sides, and the tension 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, not only a double-sided tape with a predetermined thickness but also a film-like intervening material or the like.

[0042] At this time, the concave grooves 20 are 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 apparatus configured as described above is used as the following 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 guide line 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 bonding means (ingot fixing step).

[0046] Next, the end face on the wafer W side of the SiC ingot Ig is attached to the attaching plate 2. At this time, an adhesive is applied only to the convex portions of the concave grooves 20 formed in the attaching 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 attaching plate 2 (the surface opposite to the attaching surface of the SiC ingot Ig), the spacer 30 is arranged facing the edges of the opposing sides parallel to the alignment direction of the screw holes of the tension bolt 32 (the same as the 'radial direction' of the present invention).

[0048] Then, the base plate 12 is arranged on the attaching plate 2 on which the spacer 30 is arranged so that the spacer 30 facing the through holes of the tension bolt 32 is parallel.

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

[0050] As a result, as schematically shown by the arrows in Figure 2A, a tensile load is applied in a direction that separates the central part of the adhesive plate 2 from the SiC ingot Ig (tensile load application step), thereby generating tensile stress in the adhesive plate 2 (tensile stress generation step).

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

[0052] Then, as shown in Figure 3A, when the multiple tension bolts 32 are tightened to a predetermined tightening torque, the tensile stress generated in the adhesive plate 2 (even in this state, the adhesive plate 2 itself does not deform) accumulates from each screw hole toward the spacer 30, as shown in Figure 3B.

[0053] In this state, as shown in Figures 4A and 4B, by applying an external force to the radial end on which the tensile load is applied (for example, striking with a hammer, or inserting an impact needle into the cutting guideline G and applying an impact; external force step), the adhesive plate 2 is displaced from the tensile stress point of the pull bolt 32 on the side on which the external force was applied. This displacement then propagates sequentially to the tensile stress points of the adjacent pull bolts 32, causing the adhesive plate 2 to displace in the alignment direction of the pull bolts 32 from the point of application of the external force, thereby separating the wafer W (wafer separation step).

[0054] In this way, by applying an external force to the end in the aligned direction (radial direction) where a tensile load is applied, a starting point that triggers separation is formed, and the separation can be propagated radially from this starting point where tensile stress is acting. This allows for simpler and more reliable cleavage separation by utilizing the propagation of separation due to tensile stress.

[0055] Furthermore, at this time, the deformation of the wafer W, which is integrated with the bonding plate 2, is limited to the gap between it and the base plate 31, which is defined by the thickness of the spacer 30. In other words, since the deformation of the bonding plate 2 stops when it comes into contact with the base plate 31, the bending deformation of the wafer W, which is integrated with the bonding plate 2, is limited to the gap width, thus preventing the wafer from breaking or cracking.

[0056] The above describes the details of the SiC wafer cleavage separation method of this embodiment. As explained in detail above, SiC ingots can be separated into slice-shaped SiC wafers with high precision, and high-quality SiC wafers can be manufactured simply and reliably.

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

[0058] Furthermore, although this embodiment describes a cleavage separation apparatus and method for semiconductor crystal wafers, specifically the case of cleavage separation of a SiC wafer from a SiC ingot, the semiconductor crystal is not limited to SiC and may be gallium hygroscopicum, indium phosphate, silicon, or other compound semiconductors.

[0059] Furthermore, although this embodiment describes the case in which an external force is applied to the ends in the alignment direction (radial direction), the propagation of separation due to tensile stress may be initiated by other external or internal means without applying an external force. Other external means may include sound waves (including ultrasonic waves) or thermo-optical means, and internal means may include further increases in tensile stress.

[0060] Furthermore, in this embodiment, the tensile stress generating section 3 is composed of a spacer 30, a base plate 31, and a tension bolt 32, but it is not limited to this, and any means can be used as long as a predetermined tensile load is applied to the central part of the adhesive plate. Explanation of symbols

[0061] 1...Ingot fixing part, 2...Attachment plate, 3...Tensile stress generation part, 11...Plate, 20...Recessed groove, 30...Spacer, 31...Base plate, 32...Tension 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 created by focusing a laser beam of a transparent wavelength onto the cutting surface of a cylindrical semiconductor crystal ingot, the apparatus comprising: an ingot fixing part for fixing the semiconductor crystal ingot; a bonding plate that covers the entire end face of the wafer and adheres the end face to it; and a tensile stress generating part that generates tensile stress in the bonding plate by applying a tensile load in a direction that separates the central part of the bonding plate from the semiconductor crystal ingot.

2. A wafer cleavage separation apparatus according to claim 1, wherein the tensile stress generating portion comprises a base plate attached to a part or all of the periphery of the bonding plate via a spacer, and a tension bolt having one end connected to the central part of the bonding plate via a through hole formed in the central part of the base plate.

3. A wafer cleavage separation apparatus according to claim 2, characterized in that the spacer is attached opposite to the periphery of opposite sides, and the through hole and the tension bolt are arranged in the center of the base plate parallel to the opposite sides.

4. A wafer cleavage separation apparatus according to claim 3, characterized in that the adhesive plate has a continuous groove formed on the wafer side.

5. A wafer cleavage separation apparatus according to claim 4, characterized in that the grooves are formed continuously in the direction of the opposing spacers.

6. A wafer cleavage separation method comprising: a wafer fixing step of fixing the semiconductor crystal ingot on which the cutting guideline is formed by scanning a focal point created by focusing a laser beam of a transparent wavelength onto the cutting surface of a cylindrical semiconductor crystal ingot, the method comprising: an ingot fixing step of fixing the semiconductor crystal ingot on which the cutting guideline is formed; a bonding step of bonding the entire end face of the wafer to a bonding plate; and a tensile stress generation step of generating tensile stress in the bonding plate by applying a tensile load in a direction that separates the central part of the bonding plate from the semiconductor crystal ingot.

7. A wafer cleavage separation method according to claim 6, characterized in that the tensile stress generation step involves applying a tensile load in a direction that separates the entire radial direction, including the central portion of the bonding plate, from the semiconductor crystal ingot.

8. A wafer cleavage separation method according to claim 7, characterized by comprising an external force step of applying an external force to the radial end to which the tensile load is applied.

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