DICING METHOD FOR SiC WAFER AND DEVICE THEREFOR

Abstract

To provide a dicing method for an SiC wafer which eliminates the need of a focus adjustment of a laser beam, is capable of performing dicing with a vertical wafer cross section and a designed cutting width, prevents cracking of a wafer cutting part or expansion of BPD caused by a mechanical stress or a thermal stress during the dicing, also prevents burning of the wafer cross section and is also capable of reducing residual debris on a surface of the wafer, and to provide a device therefor.SOLUTION: Water guide laser processing for cutting an SiC wafer W by passing a laser beam R through a high-pressure water beam 12 and cutting the SiC wafer W while fully reflecting the laser beam on an inner wall of a water flow when dicing the SiC wafer W is adopted. Therefore, the need of a focus adjustment of the laser beam R is eliminated, and the dicing can be performed with a vertical wafer cross section and a designed cutting width. Further, cracking of a wafer cutting part or expansion of BPD caused by a mechanical stress or a thermal stress during the dicing is prevented; burning of the wafer cross section is prevented; and residual debris on a surface of the wafer may also be reduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a SiC wafer dicing method and apparatus for dicing (dividing) a SiC wafer to obtain SiC chips. [Background technology]

[0002] Single crystal SiC (silicon carbide) is a IV-IV group compound semiconductor with a covalent crystal composition ratio of Si:C = 1:1. Single crystal SiC has a short interatomic distance between Si and C of 0.189 nm and a high bond energy of about 4.5 eV, making it a material with high phonon energy and high thermal conductivity. As a semiconductor, the strong interatomic bond strength of Si-C realizes a wide band gap and high dielectric breakdown strength. As a result, SiC has superior voltage resistance and heat resistance compared to Si (silicon), and can reduce the power loss of devices to about one-tenth, so it has attracted attention as a material for power devices. However, because SiC is harder than Si, it was not possible to efficiently separate SiC wafers using dicing with a diamond blade.

[0003] In recent years, a technology to solve this problem has been developed, for example, laser dicing, which is described in Patent Document 1. This involves irradiating a SiC wafer with laser light in a gaseous environment, vaporizing the SiC at the irradiated area, and cutting the wafer to obtain SiC chips (SiC devices). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5413861 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] However, since the laser dicing of Patent Document 1 is a dry laser process, when irradiating the SiC wafer with a laser, it is necessary to adjust the focus of the conical laser focused by a focusing lens. Furthermore, with this conventional method, the laser light that passes through the focusing lens is conical. If this light is irradiated onto the cutting line of the SiC wafer to cut the wafer, the cut surface of the wafer (machined cross section) will be tapered, making it impossible to cut the SiC wafer vertically along the designed line.

[0006] Furthermore, because dry laser dicing uses high-energy laser light, the cut sections of the SiC wafers are susceptible to mechanical and thermal stress. As a result, cracks and other defects occur in the cut sections of the wafer, making the cut surfaces rough and causing burn-in. Furthermore, evaporated debris remains near the cut sections on the wafer surface.

[0007] Incidentally, SiC power devices are composed of an active area through which current flows, and an edge termination area that is a voltage-resistance maintaining area that takes into account defects that occur during dicing. Incidentally, this device can increase the amount of current passing per chip by reducing the ratio of the edge termination area to the entire chip.

[0008] In addition, SiC power devices can have poor long-term reliability in terms of withstand voltage, and one of the causes is known to be basal plane dislocations (BPDs), a bulk defect (crystal defect). In other words, because a large current flows through a power device in the thickness direction, the device is prone to becoming hot due to resistance heating caused by the current flow, and the thermal stress when the device returns to room temperature expands the BPDs in the edge termination region, causing stacking faults and increasing the resistance value, which may ultimately lead to chip destruction.

[0009] In conventional dry laser processing of SiC wafers, the high heat generated during dicing can cause BPDs to be introduced or expanded near the cut surface of the wafer. This can ultimately cause stacking faults in the edge termination regions of the resulting SiC power devices, further reducing the voltage resistance and long-term reliability of the power devices.

[0010] Therefore, as a result of intensive research, the inventors discovered that all of the above-mentioned problems could be solved by adopting water guide laser (hereinafter sometimes referred to as WGL) processing, in which laser light is passed through a high-pressure water flow and the laser light is totally reflected by the inner wall of the water flow to cut the SiC wafer, instead of the conventional dry laser processing, and thus completed this invention.

[0011] The present invention has been made in consideration of these problems, and aims to provide a SiC wafer dicing method and apparatus which, when dicing SiC wafers, does not require focus adjustment of laser light, enables dicing with a vertical wafer cut surface and the designed cutting width, prevents the occurrence of cracks in the wafer cut portion, expansion of BPD, and stacking faults caused by mechanical stress and thermal stress during dicing, prevents burning on the wafer cut surface, and reduces debris remaining on the wafer surface. [Means for solving the problem]

[0012] The invention described in claim 1 is a method for dicing a SiC wafer, in which laser light is irradiated onto a cutting line of the SiC wafer to dice the SiC wafer, characterized in that the laser light is passed through a high-pressure water beam that moves along the cutting line, thereby dicing the SiC wafer while totally reflecting the laser light on an inner wall of the high-pressure water beam.

[0013] Any type of SiC wafer can be used. For example, 3C-SiC, 2H-SiC, 4H-SiC, 6H-SiC, 15R-SiC, etc. can be used. However, in general, 4H-SiC is used because it has high electron mobility, band gap, and dielectric breakdown field strength, small anisotropy of electrical conduction, and relatively shallow donor and acceptor levels, which allows the production of high-quality wafers and the formation of good-quality epitaxial growth layers. The size (diameter) of the SiC wafer is not limited and may be, for example, 2 to 8 inches. The thickness of the SiC wafer is also arbitrary, and may be, for example, 300 μm to 350 μm (thickness at the time of dicing: 50 μm to 200 μm).

[0014] Here, the process of dicing a SiC wafer by passing a laser beam through a high-pressure water beam that moves along the cutting line and totally reflecting the laser beam on the inner wall of the high-pressure water beam is sometimes called water guide laser (WGL) processing. In water guide laser processing, for example, by passing a laser beam through a water flow of a high-pressure water beam (water jet) ejected from a jet nozzle with a diameter of several tens of microns, the laser beam is irradiated (collides) onto the cutting line of the SiC wafer while being totally reflected by the inner wall of the high-pressure water beam. At this time, the laser beam is absorbed by the irradiated part of the SiC wafer, and this irradiated part is instantly sublimated, and immediately thereafter, it is cooled by the water flow of the high-pressure water beam. At the same time, the debris (residue) generated from the wafer cutting part is washed and removed by the water pressure of the high-pressure water beam (water jet).

[0015] The laser light oscillator oscillates a pulse laser beam having a predetermined period synchronized with a clock signal for controlling the dicing process. Any type of laser can be used. For example, green lasers such as Nd:YAG lasers and semiconductor lasers can be used. Among these, green lasers with a wavelength of 532 nm, which are not easily absorbed by water, are preferred.

[0016] The conditions of the laser light, such as wavelength, repetition frequency, output, and pulse width, are each arbitrary as long as the SiC wafer can be cut by the laser light in the irradiated high-pressure water beam. The water pressure of the high-pressure water beam may be any value that allows cutting of the SiC wafer together with the irradiated laser light, and is, for example, 50 bar to 300 bar. The diameter of the jet nozzle from which the high-pressure water beam is irradiated (ejected) is arbitrary, for example, several tens of μm. The feed speed of the high pressure water beam is also arbitrary.

[0017] In the invention described in claim 2, the laser light has a wavelength of 300 nm to 1100 nm and a peak intensity of 0.3 GW / cm 2 ~1.5GW / cm 2 The SiC wafer dicing method according to claim 1, characterized in that the high-pressure water beam is irradiated from a jet nozzle having a nozzle diameter of 20 μm to 100 μm at 50 bar to 350 bar, and the feed speed of the high-pressure water beam scanned along the cutting line is 10 mm / sec to 100 mm / sec.

[0018] If the wavelength of the laser light is less than 300 nm, the absorption rate in water is high, so the power attenuation is large and processing is not possible. Also, if it exceeds 1100 nm, the absorption rate in water is high, so the power attenuation is large and processing is not possible. The preferable wavelength of the laser light is 400 nm to 700 nm. If it is within this range, the absorption rate in water is lower, so a more preferable effect of obtaining a stable water column can be obtained.

[0019] The peak intensity of the laser beam is 0.3 GW / cm 2 Below 1.5 GW / cm, SiC wafers cannot be diced. 2 If the intensity exceeds 0.5 GW / cm, the processing quality of the single crystal SiC will deteriorate. 2 ~1.0GW / cm 2Within this range, there are no restrictions on processability, the processing quality improves, and the SiC wafer can be cut at a highly productive processing speed. The peak intensity can be calculated from the processing conditions set during processing using the following formula.

[0020] E = p / (R × t × a) E: Peak intensity (GW / cm 2 ) p: Average power (W) R: Repetition frequency (kHz) t: Pulse width (ns) a: Base area of ​​the water column (cm 2 )

[0021] If the nozzle diameter of the jet nozzle is less than 20 μm, the water column (high pressure water beam) is unstable and the laser cannot be transmitted well. If it exceeds 100 μm, the peak intensity is low and the processing efficiency is poor. The preferable nozzle diameter of the jet nozzle is 20 μm to 80 μm. If it is within this range, a more preferable effect can be obtained in that a stable water column can be maintained while obtaining the minute processing width required for SiC dicing.

[0022] If the irradiation (ejection) pressure of the high-pressure water beam is less than 50 bar, the shape of the high-pressure water beam is unstable and the laser light is not sufficiently propagated. If it exceeds 350 bar, practical operation of the high-pressure water generating unit is difficult. The preferred output of the high-pressure beam is 100 bar to 300 bar. Within this range, a further advantageous effect is obtained in that the SiC wafer can be stably processed without being cracked by the high-pressure water.

[0023] If the (processing) feed rate of the high pressure water beam is less than 10 mm / sec, the high pressure water beam is initially guided to a recess formed on the cutting line of the SiC wafer, so that processing of the recess wall surface does not progress, and as a result, a shape in which holes with a diameter of about the high pressure water beam are intermittently arranged is obtained instead of a continuous groove. Furthermore, if it exceeds 100 mm / sec, the overlap rate is low, so that the processing accuracy deteriorates and the processing depth and processing progress rate are significantly reduced. The preferred feed rate of the high pressure water beam is 20 mm / sec to 100 mm / sec. Within this range, an overlap rate of 50% or more is ensured, thereby achieving a further advantageous effect of enabling high-speed and high-quality processing.

[0024]

number

[0025] Furthermore, the invention described in claim 3 is the method of dicing a SiC wafer described in claim 1 or claim 2, characterized in that the high-pressure water beam is irradiated obliquely onto the SiC wafer, and debris within the cutting groove of the SiC wafer that appears during dicing is cleaned and removed by the water pressure.

[0026] The inclination direction and inclination angle of the high pressure water beam with respect to the SiC wafer are not limited. For example, the angle at which the high pressure water beam is inclined in the opposite direction to the movement direction of the beam irradiation point (processing point) along the cutting line based on a plane perpendicular to the plane on which the cutting line of the SiC wafer is arranged may be 5° to 70°. If it is less than 5°, the water may be unevenly concentrated and stagnate on the SiC wafer (material). If it exceeds 70°, the high pressure water may be disturbed and sufficient energy may not be transmitted to the processing point.

[0027] Under these conditions, the preferred inclination angle of the high pressure water beam with respect to the SiC wafer is 10° to 60°. In this range, the water flows easily along the inclined surface, improving the cleaning effect of the wafer surface. In addition, in the dicing process with a steep inclination, the water column becomes elliptical, so the area becomes large, which suppresses the decrease in peak intensity and enables the process to be more efficient, which is a further preferred effect. The structure for obliquely irradiating (spraying, incident) the high pressure water beam to the surface (front or back surface) of the SiC wafer on which the cutting line is arranged is arbitrary. For example, the structure may be such that the high pressure water beam and laser light side is inclined, the structure may be such that the SiC wafer side is inclined, or both of these may be used.

[0028] Furthermore, the invention described in claim 4 is a SiC wafer dicing device comprising: a laser light oscillation unit that generates a laser light; a high-pressure water generation unit that generates a high-pressure water beam to be irradiated onto a cutting line of a SiC wafer; a moving unit that moves the SiC wafer and the high-pressure water beam relatively along the cutting line when dicing the SiC wafer; a focusing lens that focuses the laser light and passes it into the high-pressure water beam; and a water chamber into which the laser light from the laser light oscillation unit and the high-pressure water from the high-pressure water generation unit are respectively introduced, and the high-pressure water beam through which the laser light has passed is ejected from a jet nozzle communicating with the inside of this chamber, wherein the laser light is totally reflected by an inner wall of the high-pressure water beam and irradiated onto the cutting line of the SiC wafer via the jet nozzle, and the SiC wafer is diced by relatively moving the SiC wafer and the high-pressure water beam by the moving unit along the cutting line.

[0029] The type of laser light oscillator may be any type that can dice a SiC wafer. For example, a Nd:YAG laser oscillator, a fiber laser oscillator, etc. may be used. The type of the high-pressure water generating unit is not limited. For example, a piston pump or a plunger pump can be used.

[0030] The structure of the water chamber can be any as long as the laser light from the laser light oscillator and the high-pressure water from the high-pressure water generator can each be introduced into the chamber, and the high-pressure water beam through which the laser light has passed can be ejected from a jet nozzle connected to the inside of the chamber. The moving means may move only the SiC wafer, only the high-pressure water beam, or both of them. In short, it is only necessary to move the irradiation point (processing point) of the high-pressure water beam through the laser light on the cutting line of the SiC wafer during dicing.

[0031] The type of moving means is not limited. For example, an XY table that is movable in a horizontal plane, an XYZ table that is movable three-dimensionally, etc. can be used. The focusing lens may have any configuration as long as it can focus the laser light and pass it through the high-pressure water beam.

[0032] In the invention described in claim 5, the laser light has a wavelength of 300 nm to 1100 nm and a peak intensity of 0.3 GW / cm 2 ~1.5GW / cm 2 The SiC wafer dicing device according to claim 4, characterized in that the high-pressure water beam is irradiated from a jet nozzle having a nozzle diameter of 20 μm to 100 μm at 50 bar to 350 bar, and the feed speed of the high-pressure water beam scanned along the cutting line is 10 mm / sec to 100 mm / sec.

[0033] Furthermore, the invention described in claim 6 is a SiC wafer dicing device as described in claim 4 or claim 5, characterized in that it has a beam irradiation angle changing means for changing the irradiation angle of the high-pressure water beam with respect to the SiC wafer, and debris that appears in the cutting groove of the SiC wafer during dicing is removed by the water pressure of the high-pressure water beam whose irradiation angle has been changed by the beam irradiation angle changing means.

[0034] The type of beam irradiation angle changing means may be any as long as it can change the incident angle of the high-pressure water beam with respect to the cutting line of the SiC wafer. For example, a means for vertically rotating an XY table (XYZ table) on which the SiC wafer is placed using a θ table may be used. Alternatively, a means for integrally moving a water chamber with a jet nozzle and a focusing nozzle using a drive unit along an arc-shaped guide rail arranged in a vertical plane, or integrally rotating the water chamber and focusing nozzle using a drive unit around a horizontal shaft may be used. Effect of the Invention

[0035] According to the inventions of claims 1 and 4, when dicing SiC wafers, instead of conventional dry laser processing, water guided laser processing is adopted, in which laser light is passed through a high-pressure water flow and the laser light is totally reflected by the inner wall of the water flow while being irradiated onto the cutting line of the SiC wafer to cut it. This eliminates the need to adjust the focus of the laser light when dicing SiC wafers, enables the wafer to be cut vertically and with the designed cutting width, and prevents the occurrence of cracks in the wafer cut section and the expansion of BPD caused by mechanical and thermal stress on the wafer cut section during dicing. It also prevents burning on the wafer cut section and reduces debris remaining on the wafer surface.

[0036] In particular, according to the inventions described in claims 2 and 5, the wavelength is 300 nm to 1100 nm, and the peak intensity is 0.3 GW / cm 2 ~1.5GW / cm 2 The pulsed laser light is passed through a high-pressure water beam irradiated at 50 bar to 350 bar from a jet nozzle with a nozzle diameter of 20 μm to 100 μm, and the high-pressure water beam is scanned along the cutting line of the SiC wafer at a feed speed of 10 mm / sec to 100 mm / sec to dices it.

[0037] As a result, when dicing the SiC wafer, the thermal effect on the cut wafer portion can be further suppressed, and the occurrence of cracks and the expansion of BPD at the cut wafer portion due to the thermal effect can be further prevented. Furthermore, the burn-in of the cut wafer surface can be further prevented, and the residual debris on the wafer surface can be further reduced.

[0038] According to the inventions described in claims 3 and 6, the SiC wafer is diced while irradiating the high-pressure water beam obliquely to the cutting line. This makes it possible to smoothly blow away, clean and remove debris in the cutting groove of the SiC wafer that appears during dicing by the water pressure of the high-pressure water beam. [Brief description of the drawings]

[0039] [Figure 1] 1 is an overall perspective view of a dicing device for a SiC wafer according to a first embodiment of the present invention. [Diagram 2] FIG. 11 is a schematic overall side view of a dicing device for a SiC wafer according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, an embodiment of the present invention will be described in detail, taking as an example a method and an apparatus for dicing a SiC wafer for a power device. EXAMPLES

[0041] In FIG. 1, reference numeral 10 denotes a SiC wafer dicing device (hereinafter, sometimes simply referred to as a dicing device) according to a first embodiment of the present invention, which dices a SiC wafer W having a diameter of 4 inches and a thickness of 350 μm.

[0042] The dicing apparatus 10 includes a laser light oscillator 11 that generates multiple laser beams R, a high-pressure water generator 13 that generates a high-pressure water beam 12 that is irradiated onto a cutting line arranged on the surface of the SiC wafer W, an XY table (moving means) 14 on which the SiC wafer W is placed and which moves it within a horizontal plane, a focusing lens L that focuses the laser light R and passes it through the high-pressure water beam 12, a water chamber 15 that introduces the laser light R from the laser light oscillator 11 and the high-pressure water from the high-pressure water generator 13 into the chamber and passes the laser light R through the high-pressure water beam 12, and a control unit 16 that controls these electrical devices.

[0043] These components will now be described in detail. The laser light oscillator 11 is a picosecond pulse laser oscillator of the Nd:YAG laser type that oscillates laser light R (green laser) with a wavelength of 532 nm.

[0044] The high-pressure water generating unit 13 is a high-pressure pump for generating the high-pressure water beam 12 jetted from the jet nozzle at 150 bar. The XY table 14 is a moving platform on which the SiC wafer W is positioned on its upper surface, and which is moved in the X and Y directions by driving an X motor 17 and a Y motor 18.

[0045] The water chamber 15 is a disc-shaped casing into which the laser light R from the laser light oscillator 11 and the high-pressure water from the high-pressure water generator 13 are respectively introduced, and into which the high-pressure water beam 12 through which the laser light R has passed is ejected from the jet nozzle 19. A transparent optical window 20 for guiding the laser light R into the chamber is provided in the center of the upper plate of the water chamber 15. Meanwhile, a jet nozzle 19 having a nozzle diameter of 80 μm is provided in the center of the lower plate of the water chamber 15. In addition, a plurality of water inlets 21 for allowing high-pressure water from the high-pressure water generator 13 to flow into the chamber are provided on the peripheral plate of the water chamber 15. The control unit 16 has a built-in central processing unit (CPU) and controls the laser light oscillator 11, the high-pressure water generator 13, the X motor 17, and the Y motor 18.

[0046] Next, a method for dicing a SiC wafer W using a dicing apparatus 10 according to the first embodiment of the present invention will be described with reference to FIG. First, high-pressure water generated by the high-pressure water generator 13 is introduced into the chamber from the peripheral side surface of the water chamber 15 through each water inlet 21. Meanwhile, the laser light oscillator 11 emits a laser beam having a repetition frequency of 10 kHz, an output of 35 W, a pulse energy of 3.5 mJ, a pulse width of 200 nanoseconds, and a peak intensity of 0.51 GW / cm. 2 Laser light R having a wavelength of 532 nm oscillated at 1000 .mu.m is focused by a focusing lens L of the optical system, and then introduced into the water chamber 15 from the top surface thereof through an optical window 20.

[0047] At this time, the optical axis of the laser beam R coincides with the nozzle axis of the jet nozzle 19. Therefore, in the water chamber 15, the laser beam R passes through the water flow of the high-pressure water beam 12 (water jet) jetted from the jet nozzle 19 at 150 bar, and the laser beam R is totally reflected by the inner wall of the water flow of the high-pressure water beam 12, and is irradiated perpendicularly onto the cutting line of the SiC wafer W disposed directly below the jet nozzle 19.

[0048] The portion of the SiC wafer W irradiated with the laser light R is sublimated by absorbing the laser light R, and immediately thereafter, this sublimated portion is cooled by the water flow of the high-pressure water beam 12. At the same time, debris (residue) remaining in the cut portion of the SiC wafer W is removed (cleaned) by the water pressure of the high-pressure water beam 12. Thereafter, the SiC wafer W is diced while appropriately moving the XY table 14 by driving the X motor 17 and the Y motor 18 based on instructions from the control unit 16 so that the high-pressure water beam 12 scans the cutting line on the surface of the SiC wafer W a predetermined number of times at a feed speed of 16.7 mm / sec.

[0049] Thus, here, instead of conventional dry laser processing, water guided laser processing is adopted for dicing the SiC wafer W, in which laser light R is passed through a high-pressure water flow and the SiC wafer W is cut while the laser light R is totally reflected by the inner wall of the water flow.

[0050] As a result, when dicing the SiC wafer W, focus adjustment of the laser light R is not required, and the wafer cut surface can be vertically diced with the designed cutting width. It also prevents cracks, chipping, and BPD (basal plane dislocations) at the cut wafer caused by the heat effect on the cut wafer during dicing. It is particularly important to prevent the occurrence of BPDs, which can become killer defects that destroy devices if they expand into stacking faults due to repeated thermal stress at high and room temperatures associated with device operation and shutdown. Furthermore, it can prevent burn-in at the cut wafer surface and reduce debris remaining on the wafer surface.

[0051] In this way, by adopting water-guide laser processing as the dicing method for the SiC wafer W, the expansion of the BPD near the wafer cut portion due to heat during dicing is suppressed. As a result, the expansion of the BPD in the edge termination region of the manufactured SiC power device is also suppressed, thereby improving the long-term voltage resistance reliability of the power device.

[0052] In addition, the wavelength is 532 nm and the peak intensity is 0.51 GW / cm 2 The pulsed laser light R is passed through a water flow of a high-pressure water beam 12 irradiated at 150 bar from a jet nozzle 19 with a nozzle diameter of 80 μm, and the high-pressure water beam 12 is scanned along the cutting line of the SiC wafer W at a feed speed of 16.7 mm / sec to dic it.

[0053] As a result, the thermal effect on the cut wafer portion can be further suppressed during dicing of the SiC wafer W, and the occurrence of cracks and the expansion of BPD at the cut wafer portion due to the thermal effect can be further prevented. Also, burn-in of the cut wafer surface can be further prevented, and the amount of debris remaining on the wafer surface can be further reduced.

[0054] Second Embodiment Next, a method and apparatus for dicing a SiC wafer according to a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 2, a feature of the dicing apparatus 10A for a SiC wafer W in the second embodiment is that it has a beam irradiation angle changing means 22 for changing the incident angle of the high-pressure water beam 12 with respect to the cutting line of the SiC wafer W.

[0055] The beam irradiation angle changing means 22 includes a θ table 23 connected to the XY table 14, a θ1 motor 24 which rotates the θ table 23 vertically around a virtual X-axis (not shown), a θ2 motor 25 which rotates the θ table 23 vertically around a virtual Y-axis (not shown), and a wafer tilt angle control unit 26 which controls these θ1 and θ2 motors 24 and 25. During dicing, the θ1, θ2 motors 24, 25 are rotated to rotate the θ table 23 vertically in a predetermined direction around the virtual X-axis or virtual Y-axis based on a command from a wafer tilt angle control unit 26 corresponding to the moving direction of the SiC wafer W, thereby adjusting the tilt angle of the SiC wafer W based on the vertical plane to 10° to 60° in the opposite direction to the wafer moving direction. As a result, debris in the cut grooves of the SiC wafer W that appears during dicing can be smoothly cleaned and removed by the water pressure of the high-pressure water beam 12 that is ideally inclined toward the surface of the SiC wafer W.

[0056] As another beam irradiation angle changing means, for example, a mechanism for tilting the entire feed table on the work side may be used (not shown). The other configurations, operations, and effects can be inferred from the first embodiment, so a description thereof will be omitted. [Industrial Applicability]

[0057] The present invention is useful as a technique for dicing SiC wafers. [Explanation of symbols]

[0058] 10,10A SiC wafer dicing machine 11 Laser light oscillator 12 High Pressure Water Beam 13 High pressure water generator 14 XY table (means of transportation) 19 Jet Nozzle 22 Beam irradiation angle changing means L Condenser lens R laser light W SiC wafer

Claims

1. 1. A method for dicing a SiC wafer, comprising: irradiating a laser beam onto a cutting line of a SiC wafer to dice the SiC wafer, the method comprising: A method for dicing a SiC wafer, comprising the steps of: passing the laser light through a high-pressure water beam that is moved along the cutting line, thereby dicing the SiC wafer while totally reflecting the laser light on an inner wall of the high-pressure water beam.

2. The laser light has a wavelength of 300 nm to 1100 nm and a peak intensity of 0.3 GW / cm 2 ~1.5 GW / cm 2 With pulsed laser light, The high-pressure water beam is irradiated from a jet nozzle having a nozzle diameter of 20 μm to 100 μm at 50 bar to 350 bar, 2. The method for dicing a SiC wafer according to claim 1, wherein a feed speed of the high-pressure water beam scanned on the cutting line is 10 mm / sec to 100 mm / sec.

3. 3. The method for dicing a SiC wafer according to claim 1, wherein the high-pressure water beam is irradiated obliquely onto the SiC wafer, and debris in the cutting groove of the SiC wafer that is exposed during dicing is cleaned and removed by the water pressure.

4. A laser beam oscillator that generates a laser beam; A high-pressure water generating unit for generating a high-pressure water beam to be irradiated onto a cutting line of the SiC wafer; a moving means for relatively moving the SiC wafer and the high-pressure water beam along the cutting line when dicing the SiC wafer; a focusing lens for focusing the laser light into the high pressure water beam; a water chamber into which the laser light from the laser light oscillator and the high-pressure water from the high-pressure water generator are respectively introduced, and the high-pressure water beam through which the laser light has passed is ejected from a jet nozzle communicating with the inside of the chamber; a high-pressure water beam that is moved relative to the SiC wafer along the cutting line by the moving means while irradiating the laser light onto the cutting line of the SiC wafer through the jet nozzle while totally reflecting the laser light on an inner wall of the high-pressure water beam, thereby dicing the Si wafer.

5. The laser light has a wavelength of 300 nm to 1100 nm and a peak intensity of 0.3 GW / cm 2 ~1.5 GW / cm 2 With pulsed laser light, The high pressure water beam is irradiated from a jet nozzle having a nozzle diameter of 20 μm to 100 μm at 50 bar to 350 bar, 5. The SiC wafer dicing apparatus according to claim 4, wherein the feed speed of the high-pressure water beam scanned on the cutting line is 10 mm / sec to 100 mm / sec.

6. a beam irradiation angle changing means for changing an irradiation angle of the high-pressure water beam with respect to the SiC wafer; 6. The SiC wafer dicing device according to claim 4, wherein debris appearing in a cutting groove of the SiC wafer during dicing is removed by the water pressure of the high-pressure water beam whose irradiation angle has been changed by the beam irradiation angle changing means.

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