JP2021170607A - Separation device - Google Patents

Abstract

To provide a separation device that can effectively separate a wafer from an ingot with a separation layer formed, while suppressing increase of the size of the device.SOLUTION: A separation device 70 includes: a high-density ultrasonic wave oscillation unit 81 having an end surface 812, for providing an ultrasonic wave densely in a center part 26 of an SiC ingot 1; a low-density ultrasonic wave oscillation unit 82 having an end surface 822, for providing an ultrasonic wave less densely in an outer periphery part 27 and forming a separation part from a part separation part to the entire surface of a wafer 20; and an ultrasonic wave provision unit 74 including a holding member 83 for holding the high-density ultrasonic wave oscillation unit 81 and the low-density ultrasonic wave oscillation unit 82; an ingot holding table 71; and a liquid supply unit 73 for supplying liquid. The ultrasonic wave provision unit 74 has the end surfaces 812 and 822 in one plane, and the holding member 83 holds parts 815 and 825 where the oscillation of an ultrasonic wave is smaller than in the end surfaces 812 and 822.SELECTED DRAWING: Figure 6

Description

The present invention relates to a peeling device.

A semiconductor wafer is generally generated by slicing an ingot with a wire saw, and the front and back surfaces of the sliced wafer are polished to a mirror surface (see, for example, Patent Document 1). However, if a single crystal SiC (silicon carbide) ingot is cut with a wire saw and the front and back surfaces are polished to generate a wafer, most of the single crystal SiC ingot is discarded, which is uneconomical. In particular, the single crystal SiC ingot has high hardness, is difficult to cut with a wire saw, and requires a considerable amount of time, resulting in poor productivity, and the high unit price of the SiC ingot makes it possible to efficiently generate a wafer. Especially has a problem.

In order to solve this problem, a technique of irradiating a single crystal SiC ingot by positioning a condensing point of a laser beam that is transparent to the single crystal SiC inside the single crystal SiC wafer to form a release layer on the planned cutting surface, and a release layer. A technique for peeling a wafer from a peeling layer formed by applying ultrasonic waves to a single crystal SiC ingot on which the wafer is formed has been proposed (see, for example, Patent Documents 2 and 3).

Japanese Unexamined Patent Publication No. 2000-094221 Japanese Unexamined Patent Publication No. 2016-111143 Japanese Patent Application No. 2018-218399

According to the techniques described in Patent Documents 2 and 3 described above, the ratio of discarded single crystal SiC ingots is lower than that in the case of cutting a single crystal SiC ingot with a wire saw to generate a wafer. Therefore, it has a certain effect on the problem of being uneconomical.

However, in order to separate the wafer from the release layer formed on the single crystal SiC ingot, it is necessary to prepare a high-density ultrasonic wave generating means and a low-density ultrasonic wave generating means, which causes a problem that the device size becomes large. was there. Therefore, we made a unit that integrates these, but in the general method of attaching a plurality of ultrasonic wave generating means to the inside of a metal plate or box and propagating vibration through these, an ultrasonic vibrator is used. It has become clear that the adhesive surface between the plate (or the box) and the plate (or box) is peeled off, which causes a new problem that ultrasonic waves cannot be efficiently transmitted and the wafer cannot be efficiently peeled off from the ingot.

The present invention has been made in view of the above facts, and an object of the present invention is a peeling device capable of efficiently peeling a wafer from an ingot on which a peeling layer is formed while suppressing an increase in the size of the device. The purpose is to provide.

In order to solve the above-mentioned problems and achieve the object, the peeling device of the present invention positions the focusing point of the laser beam having a transmissive wavelength at a depth corresponding to the thickness of the wafer to be generated. It is a peeling device that peels off the waha to be generated from the ingot that has formed the peeling layer by irradiating with. It has a high-density ultrasonic oscillation unit that forms a partially peeled part where the part of the region is peeled off by applying ultrasonic waves at a density, and an end face that faces the wafer to be generated, and is more than the part of the region. A low-density ultrasonic oscillation unit that forms a peeling portion over the entire surface of the wafer to be generated from the partial peeling portion by applying ultrasonic waves to a wide area at a low density, the high-density ultrasonic oscillation unit, and the low density. An ultrasonic applying unit including a holding member that integrally holds an ultrasonic oscillation unit, an ingot holding table that holds an ingot with the waiha to be generated facing up, a waiha to be generated, and the ultrasonic applying unit. The ultrasonic wave applying unit has a liquid supply unit that supplies liquid between the two, and the end face of the high-density ultrasonic oscillation unit and the end face of the low-density ultrasonic oscillation unit are flush with each other. The holding member is characterized in that the holding member holds a portion in which the ultrasonic vibration amplitude of the high-density ultrasonic oscillation unit and the low-density ultrasonic oscillation unit is smaller than that of the end face.

In the peeling device, the length from the portion where the amplitude of the ultrasonic vibration held by the holding member in the high-density ultrasonic oscillation unit is smaller than that of the end face to the end face facing the wafer to be generated. In the low-density ultrasonic oscillation unit, the amplitude of the ultrasonic vibration held by the holding member is equal to the length from the portion smaller than the end face to the end face facing the waiha to be generated. It may be configured.

In the peeling device, the high-density ultrasonic oscillation unit has a reduced diameter portion whose diameter is gradually reduced from a portion where the amplitude of the ultrasonic vibration is smaller than that of the end face toward the end face facing the wafer to be generated. You may have.

In the peeling device, the portion where the amplitude of the ultrasonic vibration is smaller than that of the end face may be a node portion.

The present invention has an effect that the wafer can be efficiently peeled from the ingot on which the peeling layer is formed while suppressing the increase in the size of the device.

FIG. 1 is a plan view of a SiC ingot to be processed by the peeling device according to the first embodiment. FIG. 2 is a side view of the SiC ingot shown in FIG. FIG. 3 is a perspective view of a wafer manufactured by the peeling device according to the first embodiment. FIG. 4 is a plan view showing a state in which a release layer is formed on the SiC ingot shown in FIG. FIG. 5 is a cross-sectional view taken along the line VV in FIG. FIG. 6 is a side view showing a configuration example of the peeling device according to the first embodiment. FIG. 7 is a plan view of the ultrasonic wave applying unit of the peeling device shown in FIG. 1 as viewed from below. FIG. 8 is a side view schematically showing a state in which the high-density ultrasonic oscillation unit of the peeling device according to the first embodiment applies ultrasonic waves to the central portion of the first surface of the SiC ingot. FIG. 9 is a side view schematically showing a state in which the low-density ultrasonic oscillation unit of the peeling device according to the first embodiment applies ultrasonic waves to the outer peripheral portion of the first surface of the SiC ingot. FIG. 10 is a side view schematically showing an ultrasonic wave applying unit of the peeling device according to the first modification of the first embodiment. FIG. 11 is a side view schematically showing an ultrasonic wave applying unit of the peeling device according to the second modification of the first embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
The peeling device according to the first embodiment of the present invention will be described with reference to the drawings. First, a SiC ingot, which is an ingot to be processed by the peeling apparatus according to the first embodiment, will be described. FIG. 1 is a plan view of a SiC ingot to be processed by the peeling device according to the first embodiment. FIG. 2 is a side view of the SiC ingot shown in FIG. FIG. 3 is a perspective view of a wafer manufactured by the peeling device according to the first embodiment. FIG. 4 is a plan view showing a state in which a release layer is formed on the SiC ingot shown in FIG. FIG. 5 is a cross-sectional view taken along the line VV in FIG.

(SiC ingot)
In the first embodiment, the SiC ingot 1 shown in FIGS. 1 and 2 is made of SiC (silicon carbide) and is formed in a columnar shape as a whole. In the first embodiment, the SiC ingot 1 is a hexagonal single crystal SiC ingot.

As shown in FIGS. 1 and 2, the SiC ingot 1 has a first surface 2 which is a circular end surface, a circular second surface 3 on the back surface side of the first surface 2, and an outer edge of the first surface 2. It has a peripheral surface 4 connected to the outer edge of the second surface 3. Further, the SiC ingot 1 has a first orientation flat 5 showing a crystal orientation on the peripheral surface 4 and a second orientation flat 6 orthogonal to the first orientation flat 5. The length 51 of the first orientation flat 5 is longer than the length 61 of the second orientation flat 6.

Further, the SiC ingot 1 has a c-axis 9 inclined by an off-angle α in the inclination direction 8 toward the second orientation flat 6 with respect to the perpendicular line 7 of the first surface 2, and a c-plane 10 orthogonal to the c-axis 9. There is. The c-plane 10 is inclined by an off angle α with respect to the first surface 2 of the SiC ingot 1. The inclination direction 8 of the c-axis 9 from the perpendicular line 7 is orthogonal to the extension direction of the second orientation flat 6 and parallel to the first orientation flat 5. The c-plane 10 is set in the SiC ingot 1 innumerably at the molecular level of the SiC ingot 1. In the first embodiment, the off angle α is set to 1 °, 4 ° or 6 °, but in the present invention, the off angle α is freely set in the range of, for example, 1 ° to 6 °, and the SiC ingot 1 Can be manufactured.

Further, in the SiC ingot 1, the first surface 2 is ground by a grinding device and then polished by a polishing device, so that the first surface 2 is formed into a mirror surface.

The wafer 20 shown in FIG. 3 is manufactured by peeling a part of the SiC ingot 1 and grinding, polishing, or the like on the surface 21 peeled from the SiC ingot 1. After the wafer 20 is peeled from the SiC ingot 1, a device is formed on the surface of the wafer 20. In the first embodiment, the device is a MOSFET (Metal-oxide-semiconductor Field-effect Transistor), MEMS (Micro Electro Mechanical Systems) or SBD (Schottky Barrier Diode), but in the present invention, the device is a MOSFET, MEMS and Not limited to SBD. The same parts as the SiC ingot 1 of the wafer 20 are designated by the same reference numerals, and the description thereof will be omitted.

In the SiC ingot 1 shown in FIGS. 1 and 2, after the release layer 23 shown in FIGS. 4 and 5 is formed, the wafer 20 to be generated is peeled off from the release layer 23 as a starting point. The release layer 23 sets the focusing point 32 (shown in FIG. 5) of the pulsed laser beam 31 (shown in FIG. 5) having a wavelength transparent to the SiC wafer 1 from the first surface 2 of the SiC wafer 1. A pulsed laser beam 31 along the second orientation flat 6 positioned at a desired depth 35 (shown in FIG. 5), which is a depth corresponding to the thickness 22 (shown in FIG. 3) of the wafer 20 to be generated. Is irradiated to form inside the SiC wafer 1.

When the SiC ingot 1 is irradiated with a pulsed laser beam 31 having a wavelength that is transparent to the SiC ingot 1, as shown in FIG. 5, the SiC is Si (silicon) due to the irradiation of the pulsed laser beam 31. ) And C (carbon), and the pulsed laser beam 31 to be irradiated next is absorbed by the previously formed C, and the modified portion 24 in which SiC is continuously separated into Si and C is formed. Along with being formed inside the SiC ingot 1 along the X-axis direction, a crack 25 extending from the modified portion 24 along the c-plane 10 is generated. In this way, when the SiC ingot 1 is irradiated with the pulsed laser beam 31 having a wavelength that is transparent to the SiC ingot 1, the SiC ingot 1 is formed along the modification section 24 and the modification section 24 along the c-plane 10. The release layer 23 including the crack 25 is formed.

When the SiC ingot 1 is irradiated with the laser beam 31 over the entire length in the direction parallel to the second orientation flat 6, the SiC ingot 1 and the laser beam irradiation unit (not shown) that irradiates the laser beam 31 are combined with the first orientation flat. Index feed is performed relatively along 5. Again, in the SiC ingot 1, the focusing point 32 is positioned at a desired depth from the first surface 2, and the pulsed laser beam 31 is irradiated along the second orientation flat 6, and the peeling layer 23 is formed inside. It is formed. The SiC ingot 1 repeats the operation of irradiating the laser beam 31 along the second orientation flat 6 and the operation of the laser beam irradiation unit being relatively indexed along the first orientation flat 5.

As a result, the SiC ingot 1 is provided with the modified portion 24 in which the SiC is separated into Si and C at a desired depth 35 corresponding to the thickness 22 of the wafer 20 from the first surface 2 for each movement distance of the index feed. A release layer 23 having a lower strength than other portions including the crack 25 is formed. In the SiC ingot 1, a release layer 23 is formed at a desired depth of 35 from the first surface 2 over the entire length in the direction parallel to the first orientation flat 5 for each movement distance of index feed.

(Peeling device)
Next, the peeling device will be described. FIG. 6 is a side view showing a configuration example of the peeling device according to the first embodiment. FIG. 7 is a plan view of the ultrasonic wave applying unit of the peeling device shown in FIG. 1 as viewed from below. The peeling device 70 according to the first embodiment is a device for peeling the wafer 20 to be generated shown in FIG. 4 from the SiC ingot 1 on which the peeling layer 23 is formed.

As shown in FIG. 6, the peeling device 70 includes an ingot holding table 71, a liquid supply unit 73, an ultrasonic wave applying unit 74, and a control unit 100.

The ingot holding table 71 holds the SiC ingot 1 with the wafer 20 to be generated facing up. The ingot holding table 71 has a holding surface 72 whose upper surface is parallel to the horizontal direction, and a second surface 3 of the SiC ingot 1 is placed on the holding surface 72, and the first surface 2 is directed upward to perform SiC. Hold ingot 1.

The liquid supply unit 73 supplies the liquid 75 (shown in FIGS. 8 and 9) between the wafer 20 to be generated and the ultrasonic wave applying unit 74. The liquid supply unit 73 is a pipe that supplies the liquid 75 supplied from the liquid supply source from the lower end. In the first embodiment, the liquid 75 is placed on the first surface 2 of the SiC ingot 1 held by the ingot holding table 71. To supply. Further, in the first embodiment, the liquid supply unit 73 is provided so as to be able to move up and down by an elevating mechanism (not shown).

The ultrasonic wave applying unit 74 applies ultrasonic waves 814,824 (shown in FIGS. 8 and 9) to the SiC ingot 1 held on the ingot holding table 71. As shown in FIGS. 6 and 7, the ultrasonic wave applying unit 74 includes a high-density ultrasonic oscillation unit 81, a low-density ultrasonic oscillation unit 82, and a holding member 83. The high-density ultrasonic oscillation unit 81 and the low-density ultrasonic oscillation unit 82 are formed in a direction orthogonal to the first surface 2, the holding surface 72, and the first surface 2 of the SiC ingot 1 held on the ingot holding table 71. Face to face.

In the first embodiment, one high-density ultrasonic oscillation unit 81 is provided as shown in FIG. The high-density ultrasonic oscillation unit 81 includes an ultrasonic vibrator 811 and a horn 813 having an end face 812 facing the wafer 20 to be generated, and a part region of the SiC ingot 1 including the wafer 20 to be generated. The ultrasonic wave 814 is applied to the central portion 26 of the first surface 2 at a high density. The density of the ultrasonic wave 814 in the present invention indicates the energy density of the ultrasonic wave 814 at a position separated from the end face 812 of the horn 813 by a predetermined distance.

In the first embodiment, the high-density ultrasonic oscillation unit 81 faces the central portion 26, which is a part region of the first surface 2 of the SiC ingot 1 held on the ingot holding table 71, along the direction orthogonal to the above-mentioned direction. However, in the present invention, the high-density ultrasonic oscillation unit 81 faces is not limited to the central portion 26 of the first surface 2 of the SiC ingot 1.

The ultrasonic vibrator 811 is composed of, for example, a well-known piezo element, and when power is applied from a power source (not shown), the above-mentioned orthogonality has an amplitude of several μm to several tens of μm at a frequency of 20 kHz or more and several GHz or less. It vibrates along the direction of vibration (hereinafter referred to as ultrasonic vibration). In the first embodiment, the ultrasonic vibrator 811 is a bolt-tightened Langevin type vibrator. The horn 813 is fixed to the end surface of the ultrasonic vibrator 811 near the holding surface 72 by sandwiching the holding member 83 from above and below the opening formed in the holding member 83 and tightening the bolts. The end surface 812 faces the central portion 26, which is a partial region of the first surface 2 of the SiC ingot 1 held on the ingot holding table 71, along the above-mentioned orthogonal direction.

In the first embodiment, the horn 813 is formed in a columnar shape, and the outer diameter is gradually increased toward the end face 812. Although the horn 813 is formed in a columnar shape, the present invention is not limited to this, and the horn 813 may be formed in a quadrangular prism or a polygonal prism.

In the high-density ultrasonic oscillation unit 81, the end surface 812 of the horn 813 is immersed in the liquid 75 supplied on the first surface 2 of the SiC ingot 1 held by the liquid supply unit 73 on the ingot holding table 71, and the ultrasonic waves are generated. The vibrator 811 ultrasonically vibrates to vibrate the end surface 812 of the horn 813, and ultrasonically vibrates the central portion 26 of the first surface 2 of the SiC ingot 1 via the liquid 75 (hereinafter, ultrasonic wave 814). Is given). Further, in the first embodiment, the high-density ultrasonic oscillation unit 81 applies, for example, ultrasonic waves 814 having a frequency of 100 kHz or more and 200 kHz or less to the SiC ingot 1.

A plurality of low-density ultrasonic oscillation units 82 are provided around the high-density ultrasonic oscillation unit 81. In the first embodiment, four low-density ultrasonic oscillation units 82 are provided around the high-density ultrasonic oscillation unit 81, as shown in FIG. 7. The low-density ultrasonic oscillation unit 82 includes an ultrasonic vibrator 821 and a horn 823 having an end face 822 facing the wafer 20 to be generated, and a part region of the SiC ingot 1 including the wafer 20 to be generated. The ultrasonic wave 824 is applied to the outer peripheral portion 27 of the first surface 2 having a larger area than the central portion 26 of the first surface 2 at a lower density than that of the high-density ultrasonic oscillation unit 81. As described above, the high-density ultrasonic oscillation unit 81 and the low-density ultrasonic oscillation unit 82 have different positions for applying ultrasonic waves to the first surface 2 of the SiC ingot 1.

In the first embodiment, the low-density ultrasonic oscillation unit 82 faces the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1 held on the ingot holding table 71 along the above-mentioned orthogonal direction, but in the present invention. The low-density ultrasonic oscillation unit 82 faces the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1.

The ultrasonic vibrator 821 is composed of, for example, a well-known piezo element, and when power is applied from a power source (not shown), the above-mentioned orthogonality has an amplitude of several μm to several tens of μm at a frequency of 20 kHz or more and several GHz or less. It vibrates along the direction of vibration (hereinafter referred to as ultrasonic vibration). In the first embodiment, the ultrasonic vibrator 821 is a bolt-tightened Langevin type vibrator. The end surface 822 of the horn 823 faces the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1 held on the ingot holding table 71 along the above-mentioned orthogonal direction.

In the first embodiment, the horn 823 is formed in a columnar shape, and the outer diameter is gradually increased toward the end face 822. Although the horn 823 is formed in a columnar shape, the present invention is not limited to this, and the horn 823 may be formed in a quadrangular prism or a polygonal prism. Further, in the first embodiment, the area of the end face 822 of the horn 823 of the low-density ultrasonic oscillation unit 82 is larger than the area of the end face 812 of the horn 813 of the high-density ultrasonic oscillation unit 81.

In the low-density ultrasonic oscillation unit 82, the end surface 822 of the horn 823 is immersed in the liquid 75 supplied on the first surface 2 of the SiC ingot 1 held by the liquid supply unit 73 on the ingot holding table 71, and the ultrasonic waves are generated. The vibrator 821 vibrates ultrasonically to vibrate the end surface 822 of the horn 823, and applies ultrasonic waves 824 to the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1 via the liquid 75. Further, in the first embodiment, the low-density ultrasonic oscillation unit 82 applies ultrasonic waves 824 having a frequency lower than that of the high-density ultrasonic oscillation unit 81 to the SiC ingot 1. In the first embodiment, the low-density ultrasonic oscillation unit 82 applies ultrasonic waves 824 having a frequency of, for example, 20 kHz or more and 50 kHz or less, preferably 20 kHz or more and 36 kHz or less, to the SiC ingot 1.

In the first embodiment, the area of the end face 822 of the horn 823 of the low-density ultrasonic oscillation unit 82 is larger than the area of the end face 812 of the horn 813 of the high-density ultrasonic oscillation unit 81, so that the low-density ultrasonic oscillation unit The density of the ultrasonic wave 824 applied by the 82 to the first surface 2 of the SiC ingot 1 is lower than the density of the ultrasonic wave 814 applied to the first surface 2 of the SiC ingot 1 by the high-density ultrasonic oscillation unit 81. .. Further, in the first embodiment, the area of the end face 822 of the horn 823 of the low-density ultrasonic oscillation unit 82 is larger than the area of the end face 812 of the horn 813 of the high-density ultrasonic oscillation unit 81, and the area of the low-density ultrasonic oscillation unit 82 is larger. Is provided around the high-density ultrasonic oscillation unit 81, so that the area on the first surface 2 where the low-density ultrasonic oscillation unit 82 applies the ultrasonic waves 824 is the area on the first surface 2 of the high-density ultrasonic oscillation unit 81. It is larger than the area on the first surface 2 to which the ultrasonic wave 814 is applied.

Further, in the first embodiment, in the ultrasonic wave applying unit 74, the end face 812 of the horn 813 of the high-density ultrasonic oscillation unit 81 and the end face 822 of the horn 823 of the low-density ultrasonic oscillation unit 82 are arranged on the same plane. , The end face 812 and the end face 822 are formed flush with each other.

The holding member 83 integrally holds the high-density ultrasonic oscillation unit 81 and the plurality of low-density ultrasonic oscillation units 82. In the first embodiment, the holding member 83 is formed in a flat plate shape parallel to the holding surface 72, and the amplitude of the ultrasonic vibration of the high-density ultrasonic oscillation unit 81 is smaller than that of the end surface 812. The amplitude of the ultrasonic vibration of the oscillation unit 82 is fixed to the portion 825 that is smaller than the end face 822, and the amplitude of the ultrasonic vibration of the high-density ultrasonic oscillation unit 81 and the low-density ultrasonic oscillation unit 82 is the end face 812,822. The amplitude of the ultrasonic vibration, which is a small portion as compared with that of the end face, holds the portions 815 and 825, which are small as compared with the end face. The portions 815 and 825 in which the amplitude of the ultrasonic vibration is smaller than that of the end faces 812 and 822 are the node portions in which the amplitude of the ultrasonic vibration is the smallest among the high-density ultrasonic oscillation unit 81 and the low-density ultrasonic oscillation unit 82. Will be included. In the first embodiment, the portions 815 and 825 having a smaller amplitude of ultrasonic vibration than the end faces 812 and 822 are node portions, but the present invention is not limited to the node portions.

Further, in the first embodiment, since the holding member 83 is formed in a flat plate shape parallel to the holding surface 72 in the ultrasonic wave applying unit 74, the ultrasonic waves held by the holding member 83 in the high-density ultrasonic oscillation unit 81. The length 816 from the portion 815 whose vibration amplitude is smaller than that of the end face 812 to the end face 812 facing the wafer 20 to be generated, and the ultrasonic vibration held by the holding member 83 in the low-density ultrasonic oscillation unit 82. The length 826 from the portion 825 whose amplitude is smaller than that of the end face 822 to the end face 822 facing the waiha 20 to be generated is configured to be equal. Further, in the first embodiment, the ultrasonic wave applying unit 74 is provided so as to be able to move up and down by an elevating mechanism (not shown). In the first embodiment, the liquid supply unit 73 and the ultrasonic wave applying unit 74 move up and down between the position where the ultrasonic waves 814 and 824 can be applied to the SiC ingot 1 by the elevating mechanism and the retracted position.

The control unit 100 controls the above-mentioned components of the peeling device 70 to cause the peeling device 70 to perform a machining operation on the SiC ingot 1. The control unit 100 is an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and input / output. It is a computer having an interface device. The arithmetic processing unit of the control unit 100 executes arithmetic processing according to a computer program stored in the storage device, and sends a control signal for controlling the peeling device 70 to the peeling device 70 via the input / output interface device. Output to the specified components.

The control unit 100 is connected to a display unit (not shown) composed of a liquid crystal display device for displaying the state of machining operation, an image, etc., and an input unit (not shown) used by an operator to register machining content information and the like. There is. The input unit is composed of at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

Next, the processing operation of the peeling device 70 according to the first embodiment will be described with reference to the drawings. FIG. 8 is a side view schematically showing a state in which the high-density ultrasonic oscillation unit of the peeling device according to the first embodiment applies ultrasonic waves to the central portion of the first surface of the SiC ingot. FIG. 9 is a side view schematically showing a state in which the low-density ultrasonic oscillation unit of the peeling device according to the first embodiment applies ultrasonic waves to the outer peripheral portion of the first surface of the SiC ingot.

In the peeling device 70 according to the first embodiment, the second surface 3 of the SiC ingot 1 in which the peeling layer 23 is formed is placed on the holding surface 72 of the ingot holding table 71, and the processing content information is controlled via the input unit. 100 receives and stores it in the storage device, and when the control unit 100 receives a machining start instruction from the operator, the machining operation is started.

In the processing operation, the peeling device 70 lowered the liquid supply unit 73 and brought it closer to the first surface 2 of the SiC ingot 1 held on the ingot holding table 71, and was held by the liquid supply unit 73 on the ingot holding table 71. The liquid 75 is supplied to the first surface 2 of the SiC ingot 1. The peeling device 70 lowers the ultrasonic wave applying unit 74 and brings it closer to the first surface 2 of the SiC ingot 1 held on the ingot holding table 71, and brings the end surface 812 of the high-density ultrasonic wave oscillation unit 81 of the ultrasonic wave applying unit 74. And the end face 822 of the low-density ultrasonic oscillation unit 82 is immersed in the liquid 75 on the first surface 2 of the SiC ingot 1.

As shown in FIG. 8, the peeling device 70 applies power to the ultrasonic transducer 811 of the high-density ultrasonic oscillation unit 81 for a predetermined time, and the high-density ultrasonic oscillation unit 81 uses the first surface 2 of the SiC ingot 1. Ultrasonic 814 is applied to the central portion 26 of the above. Then, the ultrasonic wave 814 from the high-density ultrasonic oscillation unit 81 is intensively irradiated to the central portion 26 of the first surface 2, stimulates the central portion 26 of the peeling layer 23, and is applied to the central portion 26 of the peeling layer 23. A partially peeled portion 28 that has been peeled off is formed starting from the peeling layer 23. In this way, the high-density ultrasonic oscillation unit 81 applies ultrasonic waves 814 at a high density to the central portion 26 of the first surface 2 of the SiC ingot 1, so that the central portion 26 of the release layer 23 is peeled off. To form.

As shown in FIG. 9, the peeling device 70 stops the application of power to the ultrasonic vibrator 811 of the high-density ultrasonic oscillation unit 81, and stops the application of power to the ultrasonic transducer 821 of the low-density ultrasonic oscillation unit 82 for a predetermined time. A power is applied to apply ultrasonic waves 824 to the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1 by the low-density ultrasonic oscillation unit 82. Then, the ultrasonic wave 824 from the low-density ultrasonic wave oscillation unit 82, which has a lower density than the ultrasonic wave 814 from the high-density ultrasonic wave oscillation unit 81, irradiates the outer peripheral portion 27 of the first surface 2 as a whole, and the release layer 23 The entire outer peripheral portion 27 of the above is stimulated, and the crack 25 extends from the partially peeled portion 28 as a starting point to form the peeled portion 29 over the entire surface of the wafer 20 to be generated from the partially peeled portion 28.

In this way, the low-density ultrasonic oscillation unit 82 applies ultrasonic waves 824 to the outer peripheral portion 27 of the first surface 2 of the SiC ingot 1 at a lower density than that of the high-density ultrasonic oscillation unit 81, so that the partial peeling portion 28 can be used. A peeling portion 29 is formed over the entire surface of the wafer 20 to be generated. The peeling device 70 divides the SiC ingot 1 from the peeling layer 23 as a starting point, separates the wafer 20 to be generated on the first surface 2 side from the SiC ingot 1, and ends the processing operation.

The wafer 20 to be generated separated from the SiC ingot 1 is adsorbed by a suction mechanism (not shown) and peeled from the SiC ingot 1, and the surface 21 peeled from the SiC ingot 1 is subjected to grinding, polishing, or the like.

As described above, in the peeling device 70 according to the first embodiment, the holding member 83 has a portion 815,825 in which the amplitude of the ultrasonic vibration of the plurality of ultrasonic oscillation units 81, 82 is smaller than that of the end faces 812,822. Since it is held, it is possible to suppress the adhesive peeling between the end faces of the horns 815 and 823 and the metal plate or box, and the holding member 83 can hold a plurality of ultrasonic oscillation units 81 and 82, and each of the ultrasonic oscillation units 81 and 82 can be held. Ultrasonic waves 814 and 824 can be efficiently applied to the SiC ingot 1 from the sound wave oscillation units 81 and 82. Further, in the peeling device 70 according to the first embodiment, the holding member 83 holds the portions 815 and 825 in which the amplitude of the ultrasonic vibration of the plurality of ultrasonic oscillation units 81 and 82 is smaller than that of the end faces 812 and 822. A plurality of ultrasonic oscillation units 81 and 82 can be held by one holding member 83, and an increase in the size of the device can be suppressed. As a result, the peeling device 70 has an effect that the wafer 20 can be efficiently peeled from the SiC ingot 1 on which the peeling layer 23 is formed, while suppressing the increase in the size of the device.

[Modification example]
A peeling device according to a modified example of the embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a side view schematically showing an ultrasonic wave applying unit of the peeling device according to the first modification of the first embodiment. FIG. 11 is a side view schematically showing an ultrasonic wave applying unit of the peeling device according to the second modification of the first embodiment. In FIGS. 10 and 11, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The ultrasonic wave applying unit 74-1 of the peeling device according to the first modification shown in FIG. 10 is configured such that the length 816 is longer than the length 827 and the holding member 83 is bent when viewed from the side. , The same as the first embodiment. In the ultrasonic wave applying unit 74-2 of the peeling device according to the modification 2 shown in FIG. 11, the horn 813 of the high-density ultrasonic oscillation unit 81 generates the ultrasonic wave vibration from the portion 815 whose amplitude is smaller than that of the end face 812. It is the same as the first embodiment except that the diameter-reduced portion 817 that gradually reduces the diameter toward the end face 812 facing the power weight 20 is provided. The reduced diameter portion 817 gradually reduces the outer diameter of the horn 813 from the portion 815 where the amplitude of the ultrasonic vibration is smaller than that of the end face 812 toward the end face 812.

In the peeling device 70 according to the first modification and the second modification, the holding member 83 holds the portions 815 and 825 in which the amplitude of the ultrasonic vibration of the plurality of ultrasonic oscillation units 81 and 82 is smaller than that of the end faces 812 and 822. Therefore, it is possible to suppress the adhesive peeling between the end faces of the horns 815 and 823 and the metal plate or box, and the peeling layer 23 is formed while suppressing the enlargement of the device size as in the first embodiment. The effect is that the waiha 20 can be efficiently peeled off from the SiC ingot 1.

Further, in the peeling device 70 according to the second modification, it is generally difficult to obtain a beautiful vibration mode (becomes a twisted vibration mode) when the horn 813 is ultrasonically vibrated at a high frequency, but the diameter of the horn 813 is reduced. Since the portion 817 is provided and the shape is tapered, the power can be concentrated and the amplitude of the ultrasonic vibration on the end face 812 can be made uniform, so that the high-density ultrasonic oscillation unit 81 can be used more efficiently. Ultrasonic wave 814 can be applied to 20.

The present invention is not limited to the above embodiment. That is, it can be modified in various ways without departing from the gist of the present invention. In the peeling device 70 of the present invention, the ingot holding table 71 may be configured to be rotatable, or the ultrasonic wave applying unit 74 may be configured to be rotatable / oscillating. Further, the peeling device 70 may include a peeling unit that adsorbs, peels, and conveys the wafer 20 after applying ultrasonic waves 814 and 824, and includes a peeling detection mechanism that detects the peeling of the wafer 20 from the SiC ingot 1. You may prepare. Further, in the present invention, the number of ultrasonic oscillation units 81 and 82 is not limited to those described in the embodiments and the like.

1 SiC ingot (ingot)
20 Wafer 22 Thickness 23 Peeling layer 26 Central part (partial area)
27 Outer circumference (wide area)
28 Partial peeling part 29 Peeling part 31 Laser beam 32 Condensing point 35 Depth 70 Peeling device 71 Ingot holding table 73 Liquid supply unit 74 Ultrasonic wave application unit 75 Liquid 81 High-density ultrasonic oscillation unit 82 Low-density ultrasonic oscillation unit 83 Holding member 812 End face 814 Ultrasonic wave 815 Part where the amplitude of ultrasonic vibration is smaller than that of the end face (node part)
816 Length 817 Reduced diameter part 822 End face 824 Ultrasonic wave 825 Part where the amplitude of ultrasonic vibration is smaller than that of the end face (node part)
826 length

Claims (4)

A peeling device that separates the wafer to be generated from the ingot that forms the separation layer by irradiating the laser beam at a depth corresponding to the thickness of the wafer to generate the focusing point of the laser beam with a transmissive wavelength. There,
A height that has an end face facing the wafer to be generated and forms a partially peeled portion where the part of the ingot containing the wafer to be generated is separated by applying ultrasonic waves at high density to a part of the ingot. Density ultrasonic oscillation unit and
It has an end face facing the wafer to be generated, and by applying ultrasonic waves at a low density to an area wider than the partial area, a peeled portion over the entire surface of the wafer to be generated is formed from the partially peeled portion. Low-density ultrasonic oscillation unit and
An ultrasonic wave imparting unit including a holding member that integrally holds the high-density ultrasonic wave oscillation unit and the low-density ultrasonic wave oscillation unit, and
An ingot holding table that holds the ingot with the wafer to be generated facing up,
A liquid supply unit that supplies a liquid between the wafer to be generated and the ultrasonic wave application unit, and
Have,
The ultrasonic wave applying unit is configured such that the end face of the high-density ultrasonic oscillation unit and the end face of the low-density ultrasonic oscillation unit are flush with each other, and the holding member is the high-density ultrasonic oscillation unit and the high-density ultrasonic oscillation unit. A peeling device characterized in that the ultrasonic vibration amplitude of a low-density ultrasonic oscillation unit holds a portion smaller than that of the end face. The length from the portion where the amplitude of the ultrasonic vibration held by the holding member in the high-density ultrasonic oscillation unit is smaller than that of the end face to the end face facing the wafer to be generated.
The length from the portion where the amplitude of the ultrasonic vibration held by the holding member in the low-density ultrasonic oscillation unit is smaller than that of the end face to the end face facing the wafer to be generated.
The peeling device according to claim 1, wherein the peeling devices are configured to be equal to each other. The high-density ultrasonic oscillation unit is characterized by having a reduced diameter portion in which the amplitude of the ultrasonic vibration is gradually reduced from a portion having a smaller amplitude than the end face toward the end face facing the wafer to be generated. The peeling device according to claim 1 or 2. The peeling device according to any one of claims 1 to 3, wherein the portion where the amplitude of the ultrasonic vibration is smaller than that of the end face is a node portion.

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