Wafer producing method

Abstract

To provide a method for producing a wafer by which an error can be easily noticed before actual processing is carried out even when the diameter of the wafer to be produced is erroneously input to a laser processing apparatus for irradiating an ingot with a laser beam.SOLUTION: The method includes a preparing step of preparing the laser processing apparatus 1, a height measuring step of measuring the height of the ingot 10, a weight measuring step of measuring the weight of the ingot 10, a diameter inputting step of inputting the diameter of the wafer to be produced, a weight calculating step of calculating the weight of the ingot from the specific gravity of the ingot, and a checking step of checking whether the weight measured in the weight measuring step and the weight calculated in the weight calculating step match each other. When the weights do not match in the checking step, the diameter of the ingot 10 is checked or the diameter input in the diameter input step is checked.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing wafers by slicing an ingot. [Background technology]

[0002] Wafers with multiple devices such as ICs and LSIs formed on their surface along planned dividing lines are then divided into individual device chips using a dicing machine or similar device, and are used in electrical equipment such as mobile phones and personal computers.

[0003] A typical wafer is produced by thinly slicing a silicon (Si) ingot and then going through processes such as beveling, grinding, etching, heat treatment, and polishing to produce a bare wafer. Devices are then formed through processes such as photoresist coating, exposure and development, and etching.

[0004] Furthermore, silicon carbide (SiC) wafers are used for power semiconductors, LEDs, etc., and the present applicant has proposed a technique for thinly slicing SiC ingots (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-111143 [Patent Document 2] Japanese Patent Application Publication No. 2019-106458 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned conventional technology is a technology in which a laser beam having a wavelength that is transparent to SiC is focused at a depth from the end face of an ingot that corresponds to the thickness of the wafer to be produced, and a peeling layer consisting of a modified layer and cracks is formed inside, thereby peeling off a wafer from the ingot.

[0007] However, the range of irradiation with the laser beam depends on the diameter of the ingot, and if the diameter of the wafer to be produced is input incorrectly into the laser processing device that irradiates the laser beam, the laser beam will only irradiate the inner region of the ingot, not reaching the outer periphery, which can cause problems such as not being able to properly produce wafers from the ingot, or the laser beam being irradiated outside the ingot, which can be dangerous. Such problems can occur not only when the diameter of the wafer to be produced is input incorrectly, but also when an ingot with a diameter different from the desired ingot is mistakenly loaded and held.

[0008] The present invention has been made in consideration of the above facts, and its main technical object is to provide a wafer production method that makes it easy to notice errors before actual processing is carried out, even if the diameter of the wafer to be produced is input incorrectly into a laser processing device that irradiates an ingot with a laser beam, or even if an ingot with a diameter different from that of the desired ingot is mistakenly loaded and held. [Means for solving the problem]

[0009] In order to solve the above-mentioned main technical problem, according to the present invention, a wafer production method for producing wafers by slicing an ingot includes a preparation step of preparing a laser processing device that irradiates the ingot with a laser beam focused at a depth corresponding to the thickness of the wafer to be produced from the end face of the ingot, thereby forming a peeled layer consisting of a modified layer and cracks inside the ingot; a height measurement step of measuring the height of the ingot; a weight measurement step of measuring the actual weight of the ingot; and a diameter input step of inputting the diameter of the wafer to be produced into the laser processing device. The wafer production method includes a weight calculation step of calculating the weight of the ingot from the height measured in the height measurement step, the diameter input in the diameter input step, and the specific gravity of the ingot, a confirmation step of confirming whether the weight measured in the weight measurement step and the weight calculated in the weight calculation step match, and if the weights match in the confirmation step, proceeding to a wafer production step of slicing the ingot to produce wafers, and if the weights do not match in the confirmation step, confirming the diameter of the ingot or confirming the diameter input in the diameter input step.

[0010] In addition to the diameter input step, it is preferable to include a material input step of inputting the material of the ingot, and if the weights match in the confirmation step, proceed to a wafer production step of slicing the ingot to produce wafers, and if the weights do not match in the confirmation step, confirm the material of the ingot in addition to the diameter of the ingot. The material of the ingot input in the material input step is preferably at least one of silicon carbide, silicon, gallium nitride, lithium tantalate, lithium niobate, diamond, and gallium oxide. [Effects of the Invention]

[0011] The wafer production method of the present invention includes a preparation step of preparing a laser processing device that positions the focal point of a laser beam at a depth corresponding to the thickness of a wafer to be produced from an end face of an ingot and irradiates the laser beam to form a peeling layer consisting of a modified layer and cracks inside the ingot; a height measurement step of measuring the height of the ingot; a weight measurement step of measuring the actual weight of the ingot; a diameter input step of inputting the diameter of the wafer to be produced into the laser processing device; a weight calculation step of calculating the weight of the ingot from the height measured in the height measurement step, the diameter input in the diameter input step, and the specific gravity of the ingot; a confirmation step of confirming whether the weight measured in the weight measurement step and the weight calculated in the weight calculation step match; and the confirmation step. If the weights match in this step, the process moves to the wafer production step in which the ingot is sliced ​​to produce wafers.If the weights do not match in the confirmation step, the diameter of the ingot is confirmed, or the diameter inputted in the diameter input step is confirmed.Therefore, even if the diameter of the wafer to be produced is inputted incorrectly to the laser processing device in the diameter input step, or even if an ingot of incorrect dimensions is placed on the holding table, the confirmation step makes it possible to notice the error in advance, thereby avoiding, for example, problems such as the laser beam not reaching the outer periphery of the ingot and irradiating only the inside, making it impossible to produce wafers from the ingot, and problems such as the laser beam being irradiated only to the outside of the ingot, which is dangerous. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is an overall perspective view of the laser processing device prepared in the preparation step. [Figure 2] FIG. 10 is a perspective view showing an embodiment of a height measurement step. [Figure 3] FIG. 10 is a perspective view showing an embodiment of a weighing process. [Figure 4] FIG. 4 is a conceptual diagram of a data table stored in a control means. [Figure 5] FIG. 1A is a perspective view showing an embodiment of a separation layer forming step in a wafer production process, and FIG. 1B is a side view showing an aspect in which a separation layer is formed by the separation layer forming step shown in FIG. [Figure 6]FIG. 10 is a perspective view showing an embodiment of a peeling step in a wafer production process. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a wafer production method according to the present invention will be described in detail with reference to the accompanying drawings.

[0014] Fig. 1 shows an overall perspective view of a laser processing apparatus 1 suitable for carrying out the wafer production method of this embodiment. The laser processing apparatus 1 is a laser processing apparatus that irradiates an ingot 10 as shown in Fig. 1 with a focused point of a laser beam positioned at a depth corresponding to the thickness of the wafer to be produced from the end face of the ingot 10, thereby forming a peeled layer consisting of a modified layer and cracks inside the ingot 10, and includes at least a holding means 3 that holds the ingot 10 and a laser irradiation means 6 that irradiates the ingot 10 held by the holding means 3 with a laser beam of a wavelength that is transparent to the ingot 10.

[0015] The laser processing apparatus 1 includes a base 2 on which a holding means 3 and a laser irradiation means 6 are mounted, a moving means 4 for moving the holding means 3 in the X-axis direction and the Y-axis direction perpendicular to the X-axis direction, an alignment means 7 for measuring the height of an ingot 10 held by the holding means 3 and detecting the processing position to be irradiated with the laser beam, a wafer peeling means 8, a display means 9, and a control means 100 for controlling each operating part. The display means 9 has a touch panel function and displays the processing status and laser processing conditions, etc., and also allows the operator to input the laser processing conditions.

[0016] As shown in FIG. 1, the holding means 3 includes a rectangular X-axis direction movable plate 31 mounted on the base 2 so as to be freely movable in the X-axis direction, a rectangular Y-axis direction movable plate 32 mounted on the X-axis direction movable plate 31 so as to be freely movable in the Y-axis direction, and a holding table 33 arranged on the Y-axis direction movable plate 32, configured to be rotatable by having a pulse motor inside, and having a flat holding surface 33a.

[0017] The moving means 4 includes an X-axis moving means 41 that moves the holding table 33 in the X-axis direction, and a Y-axis moving means 42 that moves the holding table 33 in the Y-axis direction. The X-axis moving means 41 converts the rotational motion of a motor 43 into linear motion via a ball screw 44, the end of which is supported by a bearing block 44a, and transmits the linear motion to the X-axis movable plate 31. The X-axis movable plate 31 is moved in the X-axis direction along a pair of guide rails 2a, 2a that are arranged on the base 2 along the X-axis direction. The Y-axis moving means 42 converts the rotational motion of the motor 45 into linear motion via a ball screw 46 and transmits the linear motion to the Y-axis movable plate 32, and moves the Y-axis movable plate 32 in the Y-axis direction along a pair of guide rails 35, 35 that are arranged on the X-axis movable plate 31 along the Y-axis direction.

[0018] The laser processing device 1 is provided with a frame 5 consisting of a vertical wall 5a erected on the side of the X-axis moving means 41 and the Y-axis moving means 42 on the base 2 and a horizontal wall 5b extending horizontally from the upper end of the vertical wall 5a. Inside the horizontal wall 5b of the frame 5, an optical system constituting the above-mentioned laser irradiation means 6 and part of the alignment means 7 are housed.

[0019] The wafer peeling means 8 of this embodiment is disposed on the stationary base 2 and installed near the end (on the bearing block 44a side) of the guide rails 2a. The wafer peeling means 8 includes a peeling unit case 81, a peeling unit arm 82 partially housed within the peeling unit case 81 and supported so as to be movable up and down in the Z-axis direction (vertical direction), a peeling pulse motor 83 disposed at the tip of the peeling unit arm 82, and a suction means 84 rotatably supported by the peeling pulse motor 83 below the peeling pulse motor 83 and having a plurality of suction holes on its underside. The peeling unit case 81 includes a Z-axis moving means (not shown) for controlling the movement of the peeling unit arm 82 in the Z-axis direction. The peeling unit case 81 is also provided with a Z-axis position detecting means (not shown) for detecting the position of the peeling unit arm 82 in the Z-axis direction, and a position signal from the detecting means 82 is sent to the control means 100.

[0020] The control means 100 is configured by a computer and includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program, etc., a readable / writable random access memory (RAM) that temporarily stores detected values, calculation results, etc., and an input interface and an output interface (details not shown in the drawings). In addition to the laser irradiation means 6, the control means 100 is connected to alignment means 7, X-axis movement means 41, Y-axis movement means 42, wafer peeling means 8, display means 9, etc. Also, the memory (ROM) of the control means 100 stores a data table 110 (see FIG. 4) that records, for each ingot diameter, the weight corresponding to a predetermined height (e.g., 10 mm) depending on the shape and material of the ingot, as described below.

[0021] The illustrated ingot 10 is formed into a generally cylindrical shape overall. The ingot 10 has a generally circular first end face 12a (upper face), a second end face 12b (lower face) opposite the first end face 12a and placed on the holding surface 33a of the holding table 33, and a peripheral surface 13 located between the first end face 12a and the second end face 12b. Furthermore, rectangular first and second orientation flats 14 and 15 indicating the crystal orientation are formed on the peripheral surface 13 of the ingot 10 (see also FIG. 2 ). The length of the second orientation flat 15 is set shorter than the length of the first orientation flat 14, thereby enabling the front and back faces and the crystal orientation of the ingot 10 to be reliably identified. The data table 110 described above records the weight calculated based on the shape of the ingot on which the first orientation flat 14 and the second orientation flat 15 are formed and the specific gravity of the material forming the ingot.

[0022] The laser irradiation means 6 includes an oscillator (not shown) that emits a laser beam, and a condenser 61 that irradiates the laser beam by positioning the focal point of the laser beam emitted by the oscillator at a depth corresponding to the thickness of the wafer to be produced from the end face (first end face 12a in this embodiment) of the ingot 10 held on the holding table 33.

[0023] The laser processing apparatus 1 suitable for the wafer production method of this embodiment has roughly the configuration as described above, and the wafer production method of this embodiment using the above laser processing apparatus 1 will be described below.

[0024] (preparation process) In carrying out the wafer production method of this embodiment, first, a laser processing apparatus 1 as described above is prepared, which is capable of irradiating an ingot with a laser beam focused at a depth corresponding to the thickness of the wafer to be produced, thereby forming a delamination layer consisting of a modified layer and cracks inside. Note that the laser processing apparatus 1 prepared in this preparation step is not limited to the above-described form. For example, the wafer delamination means 8 may not be provided in the laser processing apparatus 1 shown in FIG. 1, and the wafer delamination means 8 may be prepared separately from the laser processing apparatus 1.

[0025] (Height measurement process) Next, a height measurement step is performed to measure the height of the ingot. First, an ingot 10 having a predetermined thickness sufficient to produce multiple wafers is prepared. As shown in FIG. 2, the second end face 12b (bottom face) of the ingot 10 is placed on the holding table 33 of the laser processing apparatus 1. The holding table 33 is, for example, an electrostatic chuck. The holding table 33 has an electrode embedded therein, which is disposed parallel to the holding surface 33a and connected to a matching box (not shown) and a bias high-frequency power supply. When a voltage is applied to the electrode from the bias high-frequency power supply via the matching box, a dielectric polarization phenomenon occurs between the holding surface 33a and the ingot 10 placed on the holding surface 33a. The ingot 10 is attracted to and held on the holding surface 33a by an electrostatic attraction force generated by the polarization of the electric charge. Once the ingot 10 has been held on the holding table 33 in this manner, the moving means 4 is operated to move the holding table 33 to below the alignment means 7, and the alignment means 7 measures the height of the first end face 12a of the ingot 10 relative to the holding surface 33a of the holding table 33 (for example, it is assumed that the measurement is 50 mm). Information regarding the height of the ingot 10 measured by the alignment means 7 is transmitted to the control means 100 and stored in an appropriate memory.

[0026] (Weight measurement process) The actual weight of the ingot 10 held on the holding table 33 is also measured. As shown in Fig. 3, a load meter 34 is provided on the holding table 33, and is configured to be able to precisely measure the actual weight of an object placed on the holding table 33. This allows the actual weight of the ingot 10 to be measured (e.g., 3901.2 g), transmitted to the control means 100, and stored in an appropriate memory.

[0027] (Diameter input process) Furthermore, when carrying out the wafer production method of this embodiment, the operator inputs the diameter of the wafer to be produced from the ingot 10. The input is made from the display means 9 or a separate input means (such as a keyboard), and is transmitted to the control means 100 and stored in an appropriate memory. The wafer diameter is, for example, a diameter D that passes through the center O of the wafer W to be produced and is defined by the outer periphery on which the first orientation flat 14 and the second orientation flat 15 are not formed, as shown in FIG.

[0028] The above-described height measurement step, weight measurement step, and diameter input step are not limited to being performed in the order described above. The diameter input step may be performed before the above-described height measurement step and weight measurement step, or the above-described height measurement step and weight measurement step may be performed simultaneously, or the weight measurement step may be performed before the above-described height measurement step.

[0029] (Weight calculation process) The control means 100 calculates the weight of the ingot, assuming that the correct ingot has been selected, based on the height measured in the height measurement step, the diameter input in the diameter input step, and the specific gravity of the ingot material from which the desired wafer will be produced. The ingot 10 of this embodiment has a first orientation flat 14 and a second orientation flat 15 and is not a perfect cylinder. The weight is calculated based on information in a data table 110 shown in FIG. 4, more specifically, on information in the data table 110 in which weights for a specified height (e.g., 10 mm) and a specified diameter for each material with a different specific gravity are pre-recorded. Note that the weight data in the data table 110 shown in FIG. 4 is shown provisionally for the sake of convenience, and the actual weight is not limited to this information.

[0030] 4 records the materials of the ingots used to produce the wafers on which the first orientation flat 14 and the second orientation flat 15 are formed, the specific gravity of each material, and the weight (g) of the ingot when the diameter of the ingot is 100 mm, 150 mm, 200 mm, or 300 mm, which corresponds to the diameter of the wafer obtained by slicing. For example, when the material is silicon carbide (SiC), the specific gravity is 3.22, and the weight of the ingot when the diameter is 100 mm is 240.2 g, the weight when the diameter is 150 mm is 540.3 g, the weight when the diameter is 200 mm is 960.5 g, and the weight when the diameter is 300 mm is 2161.2 g (the weights of ingots made of other materials are as shown in the figure, and detailed description thereof will be omitted).

[0031] Here, the operator assumes that the wafers to be produced will be made of SiC and inputs to the control means 100 that the diameter of the wafers to be produced will be 100 mm. As described above, the height of the ingot 10 measured in the height measurement step is 50 mm, and the control means 100 calculates, based on the information in the data table 110 described above, that the weight of the ingot 10 if it were SiC would be 240.2 g × 5 = 1201.0 g, and stores this in an appropriate memory of the control means 100.

[0032] (Confirmation process) The control means 100 checks whether the weight (3901.2 g) measured in the weight measurement step matches the weight (1201.0 g) calculated in the weight calculation step. In this embodiment, to notify the operator that the weight (3901.2 g) measured in the weight measurement step does not match the weight (1201.0 g) calculated in the weight calculation step, a message prompting the operator to check the discrepancy is displayed on the display means 9 of the laser processing apparatus 1. In this case, in addition to displaying the message on the display means 9, a buzzer or the like may be used to alert the operator. This prompts the operator to check the actual diameter of the ingot 10 placed on the holding table 33 or to check whether the diameter of the wafer to be produced that the operator input in the diameter input step is correct. If the diameter input in the diameter input step is incorrect, the error is corrected. If the ingot 10 placed on the holding table 33 is incorrect, the ingot placed on the holding table 33 is replaced with the correct ingot.

[0033] If the weight measured in the weight measurement process and the weight calculated in the weight calculation process match (including cases where there is only a small difference that determines that the correct ingot is placed), the process proceeds to the wafer production process, which will be described later, in which the ingot 10 is sliced ​​to produce wafers W.

[0034] (Material input process) If multiple materials are expected for the ingot to be processed by the laser processing apparatus 1, a material input process for inputting the material of the ingot from which the desired wafer will be produced may be performed before or after the diameter input process, as necessary, before the confirmation process. The ingot material input here is transmitted to the control means 100 and stored in an appropriate memory. In the above embodiment, since a SiC wafer is produced, the operator uses the display means 9 or an appropriate input means to input, for example, that the ingot material is SiC. The ingot from which the wafer W will be produced may be selected from, for example, silicon carbide (SiC), silicon (Si), gallium nitride (GaN), lithium tantalate (LT), lithium niobate (LN), diamond (C), or gallium oxide (Ga2O3).

[0035] As described above, by inputting the material through the material input process, the material of the ingot from which the desired wafer W is produced can be more clearly identified in the control means 100, making it possible to more reliably calculate the weight of the ingot and to accommodate the production of wafers made of a variety of materials.

[0036] As described above, in the diameter input process, it is input that the diameter of the ingot required to produce the desired wafer is 100 mm, and in the material input process, it is input that the material of the ingot to produce the desired wafer is SiC.As a result, the weight of the ingot 10 estimated based on the height measured in the height measurement process is calculated to be 1201.0 g, while the actually measured weight of the ingot 10 is 3901.2 g.Since the weights do not match in the confirmation process, the operator can follow the prompts displayed on the display means 9 to confirm whether the diameter he or she input is correct, confirm the diameter of the ingot placed on the holding table 33, and further confirm the material of the ingot 10.

[0037] Based on the actual height and weight of the ingot 10 measured in the height measurement step and weight measurement step, the weight per 10 mm of the ingot 10 placed on the holding table 33 is confirmed to be 780.24 g. Using the data table 110, a search can be performed to find an approximate value (e.g., a value within a ±1% error range) that is identical to or similar to the weight of 780.24 g confirmed in the weight measurement step, thereby estimating the material and diameter of the detected value. That is, without confirming the actual diameter of the ingot 10 placed on the holding table 33, it can be estimated that the ingot 10 placed on the holding table 33 is made of lithium niobate (LN) and has a diameter of 150 mm. Therefore, the material and diameter estimated by the control unit 100 can be displayed on the display unit 9, for example. The operator can refer to this information and actually confirm the diameter and material of the ingot 10 placed on the holding table 33. The above-mentioned determination of identity can be performed by a control program configured in the control means 100, but may also be determined by an operator. Furthermore, when two or more similar values ​​are detected in the above-mentioned determination of identity, it is preferable to display all of the materials and diameters estimated based on the similar values.

[0038] In the above-mentioned confirmation step, if the actual weight of the ingot 10 measured in the above-mentioned weight measurement step matches the weight of the ingot calculated in the above-mentioned weight calculation step for producing the desired wafer W, the process proceeds to a wafer production step in which the ingot 10 is sliced ​​to produce wafers W. Note that the wafer production step described below is for the case in which the ingot 10 is SiC, and includes a separation layer formation step and a separation step.

[0039] (Wafer production process: peeling layer formation step) When carrying out the wafer production process, first, based on an image of the ingot 10 captured by the alignment means 7, the movement means 4 is operated to move and rotate the holding table 33, thereby adjusting the orientation of the ingot 10 to a predetermined orientation and adjusting the positions of the ingot 10 and the collector 61 in the XY plane. When adjusting the orientation of the ingot 10 to a predetermined orientation, as shown in Figure 5(a), the first orientation flat 14 is aligned with the Y-axis direction and the second orientation flat 15 is aligned with the X-axis direction.

[0040] Next, the condenser 61 is raised and lowered by a condenser position adjustment means (not shown) to position the condenser at a depth from the first end face 12a that corresponds to the thickness of the wafer to be produced. In this embodiment, the depth is set to, for example, 500 μm from the first end face 12a. Next, the X-axis movement means 41 of the movement means 4 is operated to feed the ingot 10 in the X-axis direction shown in the figure, while irradiating the ingot 10 from the condenser 61 with a pulsed laser beam LB having a wavelength that is transparent to SiC. At this time, at the condenser position, the SiC is separated into Si (silicon) and C (carbon) by the irradiation of the laser beam LB. The next irradiated laser beam LB is absorbed by the previously formed C, forming a modified layer 20 in which the SiC is separated into Si and C in a chain reaction. Cracks (not shown) extend from the modified layer 20 to both sides of the modified layer 20. As a result, a strip-shaped peeled strip (not shown) having a certain width extending in the X-axis direction is formed by the modified layer 20 and the cracks.

[0041] After the separation band is formed, the Y-axis moving means 42 of the moving means 4 is operated to index and feed the focal point of the laser beam LB in the Y-axis direction by a predetermined index amount (250 μm in this embodiment) so as to arrange the separation bands in parallel in the Y-axis direction. After performing the indexing in this manner, a new separation band is formed by forming the modified layer 20 in a position adjacent to the previously formed separation band according to the procedure described above. By performing the separation band formation and indexing in this manner over the entire surface of the ingot 10, a separation layer 20a consisting of multiple adjacent separation bands is formed, as shown in FIG. 5(b).

[0042] The laser processing conditions when carrying out the above-mentioned peeling layer forming step are set, for example, as follows. Wavelength: 1064nm Repetition frequency: 100kHz Pulse width: 10ns Average power: 4W Condenser lens numerical aperture (NA): 0.7 Spot size: 6.7 μm Processing feed rate: 100mm / s Peeling layer position (depth): 500 μm Index amount: 250 μm

[0043] (Wafer production process: peeling step) When performing the delamination step, first, the moving means 4 is operated to position the holding table 33 below the suction means 84 of the wafer delamination means 8. Next, the delamination unit arm 82 is lowered by the Z-axis moving means (not shown), and the lower surface of the suction means 84 is brought into close contact with the ingot 10 and adsorbed, as shown in FIG. 6 . Next, the ultrasonic vibration applying means (not shown) is operated to apply ultrasonic vibration to the lower surface of the suction means 84, and the delamination pulse motor 83 repeatedly rotates the suction means 84 in clockwise and counterclockwise directions. This allows the wafer W, as shown on the left side of the figure, to be delaminated from the delamination layer 20a formed on the ingot 10 as a starting point. After the wafer W is delaminated from the ingot 10 as shown in the figure, the upper surface of the ingot 10 (the new first end face 12a) is polished, and then the above-mentioned delamination layer forming step and delamination step are repeated to form multiple wafers W. The wafer W separated from the ingot 10 also has its separated surface polished as necessary to make it possible to form a device on one surface.

[0044] According to the above-described embodiment, even if the diameter of the wafer to be produced is input incorrectly into the laser processing apparatus 1 in the diameter input process, or even if an ingot 10 of incorrect dimensions is placed on the holding table 33, the error can be detected in advance by the confirmation process, thereby avoiding problems such as the laser beam not reaching the outer periphery of the ingot but irradiating the inside, making it impossible to produce a wafer from the ingot, and the laser beam being irradiated to the outside of the ingot, which is dangerous.

[0045] Furthermore, by inputting the ingot material in the material input step in addition to the diameter input step, errors can be more reliably detected in the confirmation step. In other words, it becomes possible to appropriately set processing conditions such as laser beam output, spot spacing, and index amount according to the ingot material. [Explanation of symbols]

[0046] 1: Laser processing equipment 2: Base 3: Holding means 31:X-axis movable plate 32: Y-axis direction movable plate 33: Holding table 33a: Holding surface 4. Transportation 41:X-axis movement means 42: Y-axis movement means 5:Frame body 5b:Horizontal wall part 6: Laser irradiation means 61: Concentrator 7: Alignment method 8: Wafer peeling means 82: Peeling unit arm 83: Pulse motor for peeling 84: Adsorption means 9:Display means 10: Ingot 12a: First end face 12b: second end face 13: Peripheral surface 14: First Orientation Flat 15: Second Orientation Flat 20: Modified layer 20a: peeling layer 100: Control means 110: Data Table W: Wafer

Claims

1. A wafer production method for slicing an ingot to produce wafers, comprising: a preparation step of preparing a laser processing device that positions a focal point of a laser beam at a depth corresponding to the thickness of a wafer to be produced from an end face of the ingot and irradiates the laser beam to form a modified layer and a peeled layer consisting of cracks inside; a height measurement step of measuring the height of the ingot; a weighing step of measuring the actual weight of the ingot; a diameter input step of inputting the diameter of a wafer to be produced into the laser processing apparatus; a weight calculation step of calculating a weight of the ingot from the height measured in the height measurement step, the diameter input in the diameter input step, and the specific gravity of the ingot; a confirmation step of confirming whether the weight measured in the weight measurement step matches the weight calculated in the weight calculation step; If the weights match in the confirmation step, the process proceeds to a wafer production step in which the ingot is sliced ​​to produce wafers; If the weight does not match in the confirmation step, the diameter of the ingot is confirmed, or the diameter inputted in the diameter input step is confirmed.

2. In addition to the diameter input step, a material input step of inputting the material of the ingot is provided, If the weights match in the confirmation step, the process proceeds to a wafer production step in which the ingot is sliced ​​to produce wafers; 2. The wafer production method according to claim 1, wherein if the weights do not match in the confirmation step, the material of the ingot is confirmed in addition to the diameter of the ingot.

3. 3. The wafer production method according to claim 2, wherein the material of the ingot input in the material input step is at least one of silicon carbide, silicon, gallium nitride, lithium tantalate, lithium niobate, diamond, and gallium oxide.

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