Wafer production method

Abstract

To provide a novel generation method of a wafer.SOLUTION: A generation method of a wafer comprises: a peeling layer formation step 101 of positioning a light condensing point of a laser beam of a wavelength having transparency with respect to an ingot, to a depth corresponded to a thickness of the wafer generated from a front surface of the ingot, and irradiating the ingot with the laser beam, and forming a peeling layer for peeling the wafer; a peeling step 102 of peeling the wafer from the ingot by using the peeling layer as a start point after the peeling layer formation step 101 is executed; and a flatness step 103 of fusing and flattening a peeled surface of the wafer by supplying energy to the peeled surface of the wafer peeled from an ingot 1 after the execution of the peeling step 102.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wafer production method for producing wafers from an ingot. [Background technology]

[0002] There is a wafer production method in which a laser beam is irradiated to a predetermined depth in an ingot to form a separation layer, and the wafer is separated from the ingot starting from the separation layer to produce a wafer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-111143 Summary of the Invention [Problem to be solved by the invention]

[0004] In the wafer production method disclosed in Patent Document 1, unevenness is formed on the delaminated surface of the wafer after the wafer is delaminated, so a step of flattening the wafer is required. Also, in the wafer production method disclosed in Patent Document 1, unevenness is also formed on the delaminated surface of the ingot, so the surface to be irradiated with the laser beam to produce the next wafer needs to be flat, so a step of flattening the delaminated surface of the ingot is also required.

[0005] Conventionally, in the wafer production method shown in Patent Document 1, rough grinding and finish grinding are performed using a grinding wheel while processing water is supplied to the wafer and ingot after delamination, and then polishing is performed using a polishing pad as necessary to achieve flatness.

[0006] Therefore, the wafer production method disclosed in Patent Document 1 required a laser beam irradiation device, a grinding device for rough grinding and finish grinding, and a polishing device for polishing to produce wafers. Also, since the thickness greater than the height of the irregularities on the peeled surface is ground to flatten it, a large thickness is removed by grinding, which poses a problem of reducing the number of wafers produced from an ingot.

[0007] An object of the present invention is to provide a new method for producing wafers. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a wafer production method of the present invention includes a delamination layer forming step of positioning a focal point of a laser beam having a wavelength that is transparent to an ingot at a depth corresponding to the thickness of a wafer to be produced from the surface of the ingot and irradiating the ingot with the laser beam to form a delamination layer for delaminating the wafer; a delamination step of delaminating the wafer from the ingot using the delamination layer as a starting point after the delamination layer forming step; and a planarization step of supplying energy to a delamination surface of the wafer delaminated from the ingot to melt and planarize the delamination surface of the wafer after the delamination step. In the peeling layer forming step, the laser beam is irradiated while a laser beam application unit that irradiates the laser beam and the ingot are moved relatively in an X-axis direction parallel to the horizontal direction, and after the laser beam has been irradiated over the entire length of the ingot in the X-axis direction, an index feed is performed in which the laser beam application unit and the ingot are moved relatively a predetermined distance in a Y-axis direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, and the laser beam irradiation and the index feed are alternately repeated. In the flattening step, energy is irradiated while moving the energy irradiating means and the wafer relatively in the X-axis direction, and after the energy has been irradiated over the entire length of the wafer in the X-axis direction, an index feed is performed in which the energy irradiating means and the wafer are moved relatively a predetermined distance in the Y-axis direction, and the energy irradiation and the index feed are alternately repeated, and the predetermined movement distance in the flattening step is equal to or less than the predetermined movement distance in the peeling layer forming step. It is characterized by the following.

[0009] The wafer production method of the present invention includes a separation layer formation step of positioning a focal point of a laser beam having a wavelength that is transparent to an ingot at a depth corresponding to the thickness of a wafer to be produced from the surface of the ingot, irradiating the ingot with the laser beam, and forming a separation layer that separates the wafer; and after performing the separation layer formation step, Applying ultrasonic vibration to the ingot, The method is characterized by comprising a delamination step of delaminating the wafer from the ingot starting from the delamination layer, and an ingot flattening step after the delamination step of supplying energy to the delamination surface of the ingot and irradiating it with a laser beam to melt and flatten the delamination surface of the ingot. In the wafer production method, in the peeling layer forming step, the laser beam is irradiated while a laser beam application unit that irradiates the laser beam and the ingot are moved relatively in an X-axis direction parallel to the horizontal direction, and after the laser beam has been irradiated over the entire length of the ingot in the X-axis direction, an index feed is performed in which the laser beam application unit and the ingot are moved relatively a predetermined distance in a Y-axis direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, and the laser beam irradiation and the index feed are alternately repeated. In the ingot flattening step, energy is irradiated while moving an energy irradiating means and the ingot relatively in the X-axis direction, and after the energy has been irradiated over the entire length of the ingot in the X-axis direction, an index feed is performed in which the energy irradiating means and the ingot are moved relatively a predetermined distance in the Y-axis direction, and the energy irradiation and the index feed are alternately repeated, and the predetermined movement distance in the ingot flattening step may be equal to or shorter than the predetermined movement distance in the peeling layer forming step.

[0010] The present inventionWafer production method the method comprises a separation layer forming step of positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of the wafer to be produced from the surface of the ingot, and irradiating the ingot with the laser beam to form a separation layer for separating the wafer; a separation step of separating the wafer from the ingot from the separation layer after the separation layer forming step; and a planarization step of supplying energy to a separation surface of the wafer separated from the ingot after the separation step to melt and planarize the separation surface of the wafer, The ingot is produced by liquid phase growth. It is characterized by:

[0011] In the wafer production method, the energy may be a laser beam. [Effects of the Invention]

[0012] The present invention has an effect of providing a new method for producing wafers. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a side view of an ingot to be processed in the wafer production method according to the first embodiment. [Figure 2] FIG. 2 is a perspective view of a wafer produced from the ingot shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the flow of the wafer production method according to the first embodiment. [Figure 4] FIG. 4 is a perspective view schematically showing a separation layer forming step in the method for producing the wafer shown in FIG. [Figure 5] FIG. 5 is a side view schematically showing the separation layer forming step of the wafer production method shown in FIG. [Figure 6] FIG. 6 is a side view schematically showing a state in which ultrasonic vibration is applied to an ingot in the separation step of the wafer production method shown in FIG. [Figure 7] FIG. 7 is a side view schematically showing a state in which a wafer is separated from an ingot in the separation step of the wafer producing method shown in FIG. [Figure 8] FIG. 8 is a perspective view schematically showing the planarization step of the wafer production method shown in FIG. [Figure 9] FIG. 9 is a perspective view schematically showing the ingot flattening step of the wafer production method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Modes (embodiments) 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. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0015] [Embodiment 1] A wafer production method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a side view of an ingot to be processed in the wafer production method according to the first embodiment. Fig. 2 is a perspective view of a wafer produced from the ingot shown in Fig. 1. Fig. 3 is a flowchart showing the flow of the wafer production method according to the first embodiment.

[0016] (ingots and wafers) The wafer production method shown in Fig. 1 according to the first embodiment is a method for producing a wafer 10 shown in Fig. 2 from an ingot 1 shown in Fig. 1. The ingot 1 shown in Fig. 1, which is the processing target of the wafer production method according to the first embodiment, is manufactured by a liquid phase epitaxy method, and in the first embodiment, is made of Si (silicon) and is formed into a cylindrical shape as a whole. Note that in the present invention, the ingot 1 may be made of Ge (germanium) or GaAs (gallium arsenide).

[0017] 1, the ingot 1 has a circular first surface 2 (corresponding to the front surface), a circular second surface 3 (corresponding to the back surface) on the reverse side of the first surface 2, and a peripheral surface 4 that connects the outer edges of the first surface 2 and the second surface 3. The ingot 1 also has an orientation flat 5 on the peripheral surface 4 that indicates the crystal orientation of the ingot 1. The orientation flat 5 is a flat surface that forms a straight line when the ingot 1 is viewed from above.

[0018] The ingot 1 has its first surface 2 roughly ground and finish ground by a grinding device, and then polished by a polishing device to form a mirror surface on the first surface 2. A portion of the ingot 1 on the first surface 2 side is peeled off, and the peeled portion is produced into the wafer 10 shown in Fig. 2. For this reason, the wafer 10 is peeled off in order from the first surface 2 side of the ingot 1, reducing its thickness.

[0019] 2, a portion including the first surface 2 of the ingot 1 is separated as the wafer 10, and the separated surface 11 separated from the ingot 1 is subjected to rough grinding, finish grinding, polishing, etc. For this purpose, the wafer 10 has the first surface 2 and the separated surface 11. The separated surface 11 is the surface of the wafer 10 separated from the ingot 1. Devices are formed in regions of the wafer 10 that are partitioned in a grid pattern by a plurality of planned division lines formed in a grid pattern on the surface of the wafer 10.

[0020] The device may be, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), a MEMS (Micro Electro Mechanical Systems), or various types of memory (semiconductor memory device). Note that the same parts of the wafer 10 as those of the ingot 1 are denoted by the same reference numerals, and their explanations will be omitted.

[0021] (Wafer Production Method) The wafer production method according to the first embodiment is a method of producing a wafer 10 by separating a portion from an ingot 1 as a wafer 10 to be produced. As shown in FIG. 3 , the wafer production method according to the first embodiment includes a separation layer formation step 101, a separation step 102, a planarization step 103, and an ingot planarization step 104.

[0022] (Release layer formation step) Figure 4 is a perspective view schematically showing a separation layer forming step in the wafer production method shown in Figure 3. Figure 5 is a side view schematically showing the separation layer forming step in the wafer production method shown in Figure 3. The separation layer forming step 101 is a step in which a focal point 22 of a laser beam 21 (shown in Figure 4) having a wavelength that is transparent to the ingot 1 is positioned at a depth 23 (shown in Figure 5) that corresponds to the thickness 12 (shown in Figure 2) of the wafer 10 to be produced from the first surface 2 of the ingot 1, and the laser beam 21 is irradiated onto the ingot 1 to form a separation layer 24 that separates the wafer 10.

[0023] In the peeling layer forming step 101, the first laser beam application device 30 sucks and holds the second surface 3 of the ingot 1 on a flat holding surface 32 along the horizontal direction of the chuck table 31. In the peeling layer forming step 101, the first laser beam application device 30 positions a focal point 22 of a pulsed laser beam 21 having a wavelength that is transparent to the ingot 1 at a depth 23 that corresponds to the thickness 12 of the wafer 10 to be manufactured from the first surface 2 of the ingot 1, and applies the laser beam 21 while moving the laser beam application unit 33 and the chuck table 31 relatively in the X-axis direction that is parallel to the horizontal direction.

[0024] When the ingot 1 is irradiated with the laser beam 21, the laser beam 21 has a wavelength that is transparent to the ingot 1, so that a modified layer is formed along the X-axis direction at a position 23 from the first surface 2 inside the ingot 1, and cracks (not shown) extending from the modified layer in a direction corresponding to the crystal orientation are generated. In this way, when the ingot 1 is irradiated with the pulsed laser beam 21 having a wavelength that is transparent to the ingot 1, a peeling layer 24 is formed inside the ingot 1 that is approximately parallel to the first surface 2 of the ingot 1 and includes the modified layer and cracks extending from the modified layer in a direction corresponding to the crystal orientation.

[0025] The modified layer refers to a region where the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area, and examples thereof include a melt-treated region, a crack region, a dielectric breakdown region, a refractive index change region, and a region where these regions are mixed. The modified layer has lower mechanical strength, etc. than other parts of the ingot 1.

[0026] In the peeling layer forming step 101, the first laser beam application device 30 forms the peeling layer 24 over the entire length of the ingot 1 in the X-axis direction, and then moves the laser beam application unit 33 and the chuck table 31 relatively a predetermined movement distance 25 (shown in FIG. 4 ) along the horizontal direction and along the Y-axis direction perpendicular to the X-axis direction (hereinafter referred to as index feed). In the peeling layer forming step 101, after the index feed, the first laser beam application device 30 positions the focal point 22 of the laser beam 21 at the depth 23 described above, and irradiates the laser beam 21 while moving the laser beam application unit 33 and the chuck table 31 relatively in the X-axis direction, thereby forming the peeling layer 24.

[0027] In the peeling layer formation step 101, the first laser beam application device 30 alternates between applying the laser beam 21 while moving the laser beam application unit 33 and the chuck table 31 relatively along the X-axis direction and index feeding, repeating this process until the peeling layer 24 is formed over the entire area below the first surface 2 of the ingot 1, thereby forming the peeling layer 24 over the entire area below the first surface 2 of the ingot 1.

[0028] (peeling step) Fig. 6 is a side view schematically showing a state in which ultrasonic vibration is applied to an ingot in the delamination step of the wafer production method shown in Fig. 3. Fig. 7 is a side view schematically showing a state in which a wafer is delaminate from an ingot in the delamination step of the wafer production method shown in Fig. 3.

[0029] The delamination step 102 is a step of delaminating the wafer 10 from the ingot 1 starting from the delamination layer 24 after the delamination layer formation step 101 is performed. In the delamination step 102, the delamination device 40 holds the second surface 3 of the ingot 1, on which the delamination layer 24 has been formed, on a flat holding surface 42 along the horizontal direction of a holding table 41.

[0030] In the peeling step 102, the peeling device 40 positions the ultrasonic wave application unit 43 above the ingot 1 held on the holding table 41 and opposite to the first surface 2 of the ingot 1 at a distance. The ultrasonic wave application unit 43 includes an ultrasonic vibrator (not shown) that expands and contracts when AC power is applied to generate ultrasonic vibrations on an opposing surface 45 that faces the first surface 2 of the ingot 1.

[0031] In the peeling step 102, the peeling device 40 supplies a liquid 46 (e.g., pure water) from a liquid supply unit 44 between the first surface 2 of the ingot 1 and the facing surface 45 of the ultrasonic wave applying unit 43. In the peeling step 102, as shown in Fig. 6, the peeling device 40 applies AC power to the ultrasonic vibrator of the ultrasonic wave applying unit 43 for a predetermined time while immersing the facing surface 45 of the ultrasonic wave applying unit 43 in the liquid 46 on the first surface 2 of the ingot 1, thereby ultrasonically vibrating the facing surface 45.

[0032] In the peeling step 102, the peeling device 40 transmits the ultrasonic vibrations of the opposing surface 45 to the first surface 2 of the ingot 1 via the liquid 46, and applies ultrasonic waves to the first surface 2 of the ingot 1 held on the holding table 41. Then, ultrasonic waves from the ultrasonic application unit 43 stimulate the peeling layer 24, and the ingot 1 is divided starting from the peeling layer 24, thereby separating the wafers 10 to be produced from the ingot 1.

[0033] In the delamination step 102, the delamination device 40 applies AC power to the ultrasonic vibrator of the ultrasonic application unit 43 for a predetermined time to ultrasonically vibrate the opposing surface 45, thereby separating the wafer 10 to be produced from the ingot 1, and then stops applying AC power to the ultrasonic vibrator of the ultrasonic application unit 43 and stops the supply of the liquid 46 from the liquid supply part 44. In the delamination step 102, the delamination device 40 moves the ultrasonic application unit 43 and the liquid supply part 44 away from above the ingot 1 held on the holding table 41.

[0034] In the peeling step 102, the peeling device 40 brings the lower surface 48 of the disk-shaped peeling unit 47 into contact with the first side 2 of the ingot 1, and suction-holds the first side 2 of the ingot 1, i.e., the wafer 10, on the lower surface 48 of the peeling unit 47. In the peeling step 102, the peeling device 40 raises the peeling unit 47, as shown in FIG. 7 , and separates the wafer 10, which is suction-held on the lower surface 48, from the ingot 1.

[0035] (flattening step) Fig. 8 is a perspective view schematically showing the planarization step of the wafer production method shown in Fig. 3. The planarization step 103 is a step in which, after the delamination step 102, energy is supplied to the delamination surface 11 of the wafer 10 delaminate from the ingot 1 to melt and planarize the delamination surface 11 of the wafer 10.

[0036] In the planarizing step 103, the second laser beam application device 50 places the first side 2 of the wafer 10, which has been separated from the ingot 1 in the separating step 102, on a flat holding surface 52 along the horizontal direction of the chuck table 51, and suction-holds the first side 2 of the wafer 10 on the holding surface 52. In the planarizing step 103, the second laser beam application device 50 positions the focal point 27 of a pulsed laser beam 26 having a wavelength absorbable by the wafer 10, i.e., the ingot 1, on the separated surface 11 of the wafer 10, and irradiates the laser beam 26, which is energy, while moving the laser beam application unit 53 and the chuck table 51 relatively in the X-axis direction, which is parallel to the horizontal direction. Thus, in the first embodiment, the laser beam 26 is irradiated as energy in the planarizing step 103.

[0037] When the wafer 10 is irradiated with the laser beam 21, the laser beam 26 has a wavelength that is absorbed by the wafer 10, and therefore the surface layer of the delamination surface 11 of the wafer 10 melts and then recrystallizes, making the delamination surface 11 flatter than immediately after it was separated from the ingot 1. In the flattening step 103, the second laser beam application device 50 irradiates the wafer 10 with the laser beam 26 over the entire length in the X-axis direction, and then moves the laser beam application unit 53 and the chuck table 51 relatively by a predetermined movement distance 28 along the horizontal direction and along the Y-axis direction that is perpendicular to the X-axis direction (hereinafter referred to as index feed).

[0038] In the planarizing step 103, after index feeding, the second laser beam application device 50 positions the focal point 27 of the laser beam 26 on the peeled surface 11, and irradiates the laser beam 26 while moving the laser beam application unit 53 and the chuck table 51 relatively in the X-axis direction, thereby melting the surface layer of the peeled surface 11 of the wafer 10, recrystallizing it, and planarizing it. Note that the movement distance 28 in the planarizing step 103 is equal to or less than the movement distance 25 in the peeled layer forming step 101.

[0039] In the planarization step 103, the second laser beam application device 50 alternately repeats the irradiation of the laser beam 26 while moving the laser beam application unit 53 and the chuck table 51 relatively along the X-axis direction and index feeding, thereby melting the surface layer of the entire peeled surface 11, recrystallizing it, and flattening it. After the planarization step 103, the peeled surface 11 of the wafer 10 is finish-ground and polished with a grinding wheel according to the required flatness, and then devices are formed on the surface. If sufficient flatness can be achieved by the planarization step 103, the finish-grinding step may be omitted and only the polishing step may be performed.

[0040] (ingot flattening step) Fig. 9 is a perspective view schematically showing the ingot flattening step of the wafer production method shown in Fig. 3. The ingot flattening step 104 is a step in which, after the separation step 102, energy is supplied to the separation surface 6 (shown in Fig. 7) of the ingot 1 from which the wafer 10 has been separated, thereby melting and flattening the separation surface 6 of the ingot 1. The separation surface 6 is the surface from which the wafer 10 has been separated from the ingot 1.

[0041] In the ingot flattening step 104, the second side 3 of the ingot 1, from which the wafer 10 was separated in the separation step 102, is placed on the holding surface 52 of the chuck table 51, and the second laser beam application device 50 suction-holds the second side 3 of the ingot 1 on the holding surface 52. In the ingot flattening step 104, the second laser beam application device 50 positions the focal point 27 of the pulsed laser beam 26, which has a wavelength absorbable by the ingot 1, on the separated surface 6 of the ingot 1, and irradiates the laser beam 26, which is energy, while moving the laser beam application unit 53 and the chuck table 51 relatively in the X-axis direction. Thus, in the ingot flattening step 104 in the first embodiment, the laser beam 26 is irradiated as energy.

[0042] When the ingot 1 is irradiated with the laser beam 21, the laser beam 26 has a wavelength that is absorbed by the ingot 1, so that the surface layer of the delamination surface 6 of the ingot 1 melts and recrystallizes, making the delamination surface 6 flatter than immediately after the wafer 10 is delaminate. In the ingot flattening step 104, the second laser beam application device 50 irradiates the ingot 1 with the laser beam 26 over the entire length in the X-axis direction, and then moves the laser beam application unit 53 and the chuck table 51 relatively a predetermined movement distance 29 along the Y-axis direction (hereinafter referred to as index feed).

[0043] In the ingot flattening step 104, after index feeding, the second laser beam application device 50 positions the focal point 27 of the laser beam 26 on the peeled surface 6, and irradiates the laser beam 26 while moving the laser beam application unit 53 and the chuck table 51 relatively in the X-axis direction, thereby melting the surface layer of the peeled surface 6 of the ingot 1, recrystallizing it, and flattening it. Note that the movement distance 29 in the ingot flattening step 104 is equal to or less than the movement distance 25 in the peeled layer forming step 101.

[0044] In the ingot flattening step 104, the second laser beam application device 50 alternately repeats the irradiation of the laser beam 26 while moving the laser beam application unit 53 and the chuck table 51 relatively along the X-axis direction and index feeding, thereby melting the surface layer of the entire delamination surface 6, and then recrystallizing and flattening it. After the ingot flattening step 104, the delamination surface 6 of the ingot 1 is finish-ground and polished as necessary to form the first surface 2. Thereafter, the ingot 1 is again delaminate-separated from the first surface 2 side to form the wafer 10. In this way, the thickness of the ingot 1 is reduced as the wafer 10 is delaminate-separated, and a delamination layer 24 is formed until the predetermined thickness is reached, and a portion is delaminate-separated as the wafer 10.

[0045] As described above, in the wafer production method according to the first embodiment, in the planarization step 103, the laser beam 26 as energy is irradiated onto the delaminated surface 11 of the wafer 10 separated from the ingot 1, thereby planarizing the delaminated surface 11 of the wafer 10. For this reason, the wafer production method according to the first embodiment does not require rough grinding while supplying processing water to the wafer 10 separated from the ingot 1, and planarization can be achieved by irradiating the wafer with the laser beam 26, which does not require processing water.

[0046] As a result, the wafer production method according to the first embodiment has the effect of providing a new wafer production method. Also, the wafer production method according to the first embodiment has the effect of suppressing the thickness of the wafer 10 and the ingot 1 to be removed by melting and flattening in the flattening steps 103 and 104, compared to removing all the irregularities by grinding.

[0047] Furthermore, the wafer production method according to embodiment 1 does not require rough grinding while supplying processing water to the wafer 10 peeled from the ingot 1, and the peeled surface 11 is flattened, so that the amount of grinding of the wafer 10 can be reduced and the material yield of the wafer 10 can be improved.

[0048] In the wafer production method according to the first embodiment, in the ingot flattening step 104, the delaminated surface 6 of the ingot 1 from which the wafer 10 has been separated is irradiated with a laser beam 26 as energy to flatten the delaminated surface 6 of the ingot 1. For this reason, in the wafer production method according to the first embodiment, it is not necessary to perform rough grinding while supplying processing water to the ingot 1 from which the wafer 10 has been separated, and flattening is achieved by irradiating the ingot 1 with the laser beam 26, which does not require processing water.

[0049] Furthermore, the wafer production method according to embodiment 1 does not require rough grinding while supplying processing water to the ingot 1 from which the wafer 10 has been separated, and the separated surface 6 is flattened, thereby reducing the amount of grinding of the ingot 1 and improving the material yield of the ingot 1.

[0050] Furthermore, in the wafer production method according to embodiment 1, since the ingot 1 is manufactured by a liquid phase growth method, these peeled surfaces 6, 11 can be melted and flattened by irradiating them with a laser beam 26 in the flattening step 103 and the ingot flattening step 104.

[0051] The present invention is not limited to the above-described embodiment. In other words, various modifications can be made without departing from the gist of the present invention. In the first embodiment, the laser beam 26 is irradiated onto the peeled surfaces 6 and 11 as energy in the planarization step 103 and the ingot planarization step 104. However, in the present invention, an ion beam may be irradiated as energy, or an etching gas in plasma form may be irradiated as energy to plasma-etch the peeled surfaces 6 and 11.

[0052] In addition, the present invention may perform either the planarization step 103 or the ingot planarization step 104, and planarize only either the wafer 10 or the ingot 1 by one of the methods of the planarization step 103 and the ingot planarization step 104, or may perform both the planarization step 103 and the ingot planarization step 104, and planarize both the wafer 10 and the ingot 1 by the methods of the planarization step 103 and the ingot planarization step 104. [Explanation of symbols]

[0053] 1 ingot 2 First side (front) 6 Peeling surface 10 wafers 11 Peeling surface 12 Thickness 21 Laser beam 22 Focus point 23 Depth 24 Peeling layer 26 Laser beam (energy) 101 Peeling layer formation step 102 Peeling step 103 Flattening Step 104 Ingot Flattening Step

Claims

1. a separation layer forming step of positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of the wafer to be produced from the surface of the ingot and irradiating the ingot with the laser beam to form a separation layer that separates the wafer; After the separation layer forming step is performed, a separation step of separating the wafer from the ingot starting from the separation layer; a planarization step of supplying energy to the delaminated surface of the wafer delaminated from the ingot after the delamination step, thereby melting and planarizing the delaminated surface of the wafer; Equipped with In the peeling layer forming step, the laser beam is irradiated while a laser beam irradiation unit that irradiates the laser beam and the ingot are relatively moved in an X-axis direction parallel to the horizontal direction, and when the laser beam has been irradiated over the entire length of the ingot in the X-axis direction, the laser beam irradiation unit and the ingot are index-fed to move relatively a predetermined distance in a Y-axis direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, and the irradiation of the laser beam and the index-fed are alternately repeated. In the planarization step, energy is irradiated while the energy irradiating means and the wafer are moved relatively in the X-axis direction, and when the energy has been irradiated over the entire length of the wafer in the X-axis direction, the energy irradiating means and the wafer are indexed to move relatively a predetermined distance in the Y-axis direction, and the energy irradiation and the indexing are alternately repeated. The predetermined movement distance in the planarization step is equal to or less than the predetermined movement distance in the release layer formation step. A method for producing a wafer, characterized by the above.

2. a separation layer forming step of positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of the wafer to be produced from the surface of the ingot and irradiating the ingot with the laser beam to form a separation layer that separates the wafer; a delamination step of applying ultrasonic vibration to the ingot after the delamination layer formation step to delaminate the wafer from the ingot starting from the delamination layer; an ingot flattening step of supplying energy to the peeled surface of the ingot and irradiating it with a laser beam to melt and flatten the peeled surface of the ingot after the peeling step; A wafer production method comprising:

3. In the peeling layer forming step, the laser beam is irradiated while a laser beam irradiation unit that irradiates the laser beam and the ingot are moved relatively in an X-axis direction parallel to the horizontal direction, and when the laser beam has been irradiated over the entire length of the ingot in the X-axis direction, an index feed is performed to move the laser beam irradiation unit and the ingot relatively a predetermined distance in a Y-axis direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, and the irradiation of the laser beam and the index feed are repeated alternately, In the ingot flattening step, energy is irradiated while the energy irradiating means and the ingot are moved relatively in the X-axis direction, and when the energy has been irradiated over the entire length of the ingot in the X-axis direction, the energy irradiating means and the ingot are indexed to move relatively a predetermined distance in the Y-axis direction, and the energy irradiation and the indexed movement are alternately repeated. The predetermined movement distance in the ingot flattening step is equal to or less than the predetermined movement distance in the peeling layer forming step.

3. The method for producing a wafer according to claim 2, wherein:

4. a separation layer forming step of positioning a focal point of a laser beam having a wavelength that is transparent to the ingot at a depth corresponding to the thickness of the wafer to be produced from the surface of the ingot and irradiating the ingot with the laser beam to form a separation layer that separates the wafer; After the separation layer forming step is performed, a separation step of separating the wafer from the ingot starting from the separation layer; a planarization step of supplying energy to the delaminated surface of the wafer delaminated from the ingot after the delamination step, thereby melting and planarizing the delaminated surface of the wafer; Equipped with The method for producing a wafer is characterized in that the ingot is produced by a liquid phase growth method.

5. 3. The method for producing a wafer according to claim 1, wherein the energy is a laser beam.

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