Processing method, processing apparatus, and substrate manufacturing method

Abstract

The present invention provides a processing method and apparatus capable of flattening a workpiece doped with impurities to a uniform thickness. [Solution] The processing method comprises an impurity concentration acquisition step S10 in which data on the impurity concentration of the workpiece is acquired, and a flattening step (grinding step S40, polishing step S50) in which one surface of the workpiece held on the holding table 51 is ground or polished in a flattening processing unit to flatten it. The flattening step flattens one surface of the workpiece based on the data acquired in the impurity concentration acquisition step S10.

Description

Technical Field

[0001] The present invention relates to a processing method and a processing apparatus.

Background Art

[0002] In the manufacturing process of a semiconductor wafer, after being ground to a predetermined thickness, the surface is polished. Regarding such polishing, for example, Patent Document 1 discloses a technique of changing the shape of a polishing pad in the radial direction according to the thickness distribution in the radial direction of the wafer in order to equalize the thickness of the wafer after polishing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the SiC single crystal, impurities such as nitrogen are generally doped in the growth process to impart conductivity. When polishing a workpiece doped with impurities, the polishing rate changes according to the impurity concentration, so that the workpiece may not be flattened to an even thickness in the polishing process.

[0005] The present invention provides a processing method and a processing apparatus capable of flattening a workpiece doped with impurities to an even thickness.

Means for Solving the Problems

[0006] The present invention is an impurity concentration acquisition step of acquiring data regarding the impurity concentration of a workpiece, and a flattening step of grinding or polishing one surface of the workpiece held on a holding table with a flattening processing unit to flatten it, and is a processing method comprising: The planarization step planarizes one surface of the workpiece based on the data obtained in the impurity concentration acquisition step.

[0007] Furthermore, the present invention is A processing apparatus for processing one side of a workpiece held on a holding table, A spindle that extends in a predetermined direction and is rotatably mounted, A mount fixed to the tip of the spindle, The system includes a flattening section fixed to the mount, which grinds or polishes one surface of the workpiece to make it flat, Based on data relating to the impurity concentration of the workpiece, the processing apparatus flattens one surface of the workpiece in the flattening section. [Effects of the Invention]

[0008] According to the present invention, since one surface of the workpiece is flattened based on data regarding impurity concentration, variations in the thickness of the workpiece can be reduced, and as a result, the workpiece can be flattened to a uniform thickness. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of ingot 1 and wafer 2, which has been peeled off from ingot 1. [Figure 2] Figure 2 is a front view of ingot 1 (wafer 2), showing an example of the distribution of impurity concentrations in ingot 1 (wafer 2). [Figure 3] Figure 3 is a flowchart of the processing method according to the first embodiment. [Figure 4] Figure 4 schematically shows a resistance meter 11 capable of performing the impurity concentration acquisition step S10. [Figure 5] Figure 5 is a schematic diagram showing a detection device 20 capable of performing the impurity concentration acquisition step S10. [Figure 6] Figure 6 is a schematic diagram of the laser beam irradiation mechanism 30 that performs the peeling initiation step S20. [Figure 7] FIG. 7 is a view showing a state in which a laser beam is irradiated from the surface 1a of the ingot 1 by the laser beam irradiation mechanism 30. [Figure 8] FIG. 8 is a schematic view (part 1) of the peeling device 40 that performs the peeling step S30. [Figure 9] FIG. 9 is a schematic view (part 2) of the peeling device 40 that performs the peeling step S30. [Figure 10] FIG. 10 shows a modification example of the ultrasonic oscillation unit 42 of the peeling device 40. [Figure 11] FIG. 11 is a perspective view of the grinding device 50 that performs the grinding step S4 @ 0. [Figure 12] FIG. 12 is a schematic configuration diagram showing the configuration of the polishing device 60 that performs the polishing step S50. [Figure 13] FIG. 13 is a flowchart of the processing method of the second embodiment. [Figure 14] FIG. 14 is a schematic configuration diagram showing the configuration of the dressing mechanism 80 that performs the shaping step S45. [Figure 15] FIG. 15 is a schematic view showing an example of the shaped polishing pad 64. [Figure 16] FIG. 16 is a schematic view showing another example of the shaped polishing pad 64.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, each embodiment of the processing method and processing device of the present invention will be described based on the accompanying drawings.

[0011] FIG. 1 is a schematic view of an ingot 1 and a wafer 2 peeled off from the ingot 1. The ingot 1 is, for example, a Si single crystal ingot or a SiC single crystal ingot. The ingot 1 is formed in a columnar shape, and a wafer 2, which is a disc-shaped substrate, is manufactured by peeling off the wafer 2 from the surface 1a of the ingot 1. In FIG. 1, reference numeral 2a denotes the peeling surface 2a of the wafer 2 peeled off from the surface 1a of the ingot 1, and reference numeral 1b denotes the back surface 1b, which is the surface on the opposite side of the surface 1a in the thickness direction of the ingot 1.

[0012] The ingot 1 is doped with impurities in order to impart conductivity during its growth process. For example, taking the case of a SiC single crystal ingot as an example, nitrogen is doped as an impurity. Although the amount of impurities doped into the ingot 1 is controlled, there are variations in the impurity concentration for each individual ingot 1. That is, the average value of the impurity concentration is different for each ingot 1.

[0013] In addition, the impurities are not uniformly doped within the ingot 1, and there is a distribution of impurity concentration. Since the distribution of the impurity concentration also varies depending on the position in the thickness direction of the ingot 1, for a plurality of wafers 2 peeled off from the ingot 1, the average value of the impurity concentration is different for each, and the distribution of the impurity concentration is also different for each.

[0014] Specifically explaining the distribution of the impurity concentration in the ingot 1, in the ingot 1, a facet region F, which is a region flat at the atomic level, is locally formed during the growth process of the single crystal. The facet region F is formed in a columnar shape from the surface 1a to the back surface 1b of the ingot 1. Since impurities are more likely to be incorporated into the facet region F than other parts (also referred to as non-facet regions), the impurity concentration in the facet region F is higher than the impurity concentration in the non-facet regions.

[0015] Figure 2 is a front view of ingot 1 (wafer 2), showing an example of the distribution of impurity concentration in ingot 1 (wafer 2). The shaded area represents facet region F. In one example shown in Figure 2(a), facet region F is formed near the outer left edge of ingot 1 (wafer 2) in the figure, while the other areas are non-facet regions. In another example shown in Figure 2(b), facet region F is formed in the central part of ingot 1 (wafer 2), while the other areas are non-facet regions.

[0016] [First Embodiment] First, a first embodiment of the processing method of the present invention will be described.

[0017] Figure 3 is a flowchart of the processing method of the first embodiment. The processing method of the first embodiment includes an impurity concentration acquisition step S10 for acquiring data on the impurity concentration of the ingot 1, a peeling initiation point formation step S20 for forming a peeling initiation point 4 (see Figure 6) on the ingot 1, a peeling step S30 for peeling the wafer 2 from the ingot 1, a grinding step S40 for grinding the peeled surface 2a of the peeled wafer 2, and a polishing step S50 for polishing the peeled surface 2a of the ground wafer 2. The grinding step S40 and the polishing step S50 are also sometimes called planarization steps. The ingot 1 and wafer 2 are the objects of processing in this processing method and are also sometimes called "workpieces".

[0018] (Step to obtain impurity concentration) The impurity concentration acquisition step S10 acquires data regarding the impurity concentration of ingot 1. This data includes, for example, the average value of the impurity concentration and / or the distribution of the impurity concentration. Since wafer 2 is separated from ingot 1, it can also be said that the impurity concentration acquisition step S10 acquires data regarding the impurity concentration of wafer 2.

[0019] Specifically, in the impurity concentration acquisition step S10, the electrical resistance value of the surface 1a of the ingot 1 is measured, and data regarding the impurity concentration is acquired based on the electrical resistance value.

[0020] Figure 4 schematically shows a resistance meter 11 capable of performing the impurity concentration acquisition step S10. The resistance meter 11 measures the electrical resistance of the surface 1a of the ingot 1. The resistance meter 11 may be either non-contact or contact type. The electrical resistance measured by the resistance meter 11 may be electrical resistance or electrical resistivity.

[0021] In the impurity concentration acquisition step S10, the resistance meter 11 is positioned facing the surface 1a of the ingot 1 and measures the electrical resistance. The resistance meter 11 may be provided to be able to move up and down by a lifting mechanism, or it may be provided to be able to move in a direction parallel to the surface 1a (horizontal direction). The resistance meter 11 transmits a signal including the measured electrical resistance to the control device 12.

[0022] The control device 12 includes a processor that performs calculations according to a program, and memory such as ROM (Read Only Memory) and RAM (Random Access Memory). Based on the received signal including the electrical resistance value, the control device 12 calculates or refers to a pre-created map to acquire data on impurity concentration.

[0023] Another example of the impurity concentration acquisition step S10 is to irradiate the surface 1a of the ingot 1 with excitation light of a predetermined wavelength and acquire data on the impurity concentration based on a predetermined detection result of fluorescence produced by the excitation light. As will be described in detail later, the predetermined detection result may be, for example, the number of photons of the fluorescence in the infrared region wavelength or the fluorescence brightness.

[0024] Figure 5 is a schematic diagram showing a detection device 20 capable of performing the impurity concentration acquisition step S10. The detection device 20 comprises a disc-shaped holding table 21 for holding the ingot 1, a detection unit 22 provided above the holding table 21, and a control device 29.

[0025] The holding table 21 holds the ingot 1, which is placed on the holding surface 21a, by suction using a suction source (not shown). The holding table 21 is rotatable about a central axis extending in a direction perpendicular to the holding surface 21a (vertical direction) by a spindle and motor, etc. The holding table 21 is also movable along a direction parallel to the holding surface 21a (horizontal direction) and / or vertical direction by a ball screw and motor, etc.

[0026] The detection unit 22 includes an excitation light source 23, a mirror 24, a focusing lens 25, an annular elliptical mirror 26 having a reflective surface 26a on its inside, a filter 27, and a light receiving unit 28. The detection unit 22 is mounted to be movable along the horizontal and / or vertical directions by means of a ball screw and a motor or the like.

[0027] The excitation light source 23, for example, has a GaN-based light-emitting element and irradiates the ingot 1 with excitation light A at a wavelength absorbed by the ingot 1 (for example, 365 nm) toward the side mirror 24. The excitation light A reflected by the mirror 24 is then focused by the downward focusing lens 25.

[0028] The reflective surface 26a of the elliptic mirror 26 corresponds to a part of the surface of a spheroid obtained by rotating an ellipse 26b, which has a major axis extending vertically and a minor axis extending horizontally, around the major axis. The elliptic mirror 26 has two focal points F1 and F2, and focuses light generated from one of them (e.g., focal point F1) to the other (e.g., focal point F2). The focusing lens 25 is designed so that its focal point approximately coincides with focal point F1. That is, the excitation light A is focused at focal point F1.

[0029] The filter 27 is located in the optical path between the focal points F1 and F2 of the elliptical mirror 26. In the detection unit 22, light generated at focal point F1 and reflected by the elliptical mirror 26 passes through the filter 27 and heads towards focal point F2. The filter 27 is, for example, an infrared filter that transmits light with wavelengths of 750 nm or longer and blocks light with wavelengths less than 750 nm.

[0030] The light-receiving unit 28 is positioned such that the center of the light-receiving surface 28a coincides with the focal point F2 of the elliptical mirror 26. The light-receiving unit 28 includes, for example, a photomultiplier tube that, when it receives light with a wavelength of less than or equal to a predetermined value (for example, 900 nm or less, 1200 nm or less, or 1500 nm or less), outputs an electrical signal indicating the number of photons in the light.

[0031] The control device 29 includes a processor that performs calculations according to a program, and memory such as ROM and RAM. Based on the detection results of the light receiving unit 28, the control device 29 calculates or refers to a pre-created map to acquire data on impurity concentration.

[0032] Identifying regions of the ingot 1 with different impurity concentrations (e.g., faceted regions and non-faceted regions) using the detection device 20 is performed, for example, in the following order. First, with the back surface 1b of the ingot 1 held on the holding surface 21a of the holding table 21, the horizontal position of the holding table 21 and the vertical position of the detection unit 22 are adjusted so that the focal point F1 of the elliptical mirror 26 coincides with a point on the surface 1a of the ingot 1. Specifically, the holding table 21 and the detection unit 22 are moved so that the focal point F1 coincides with one of a plurality of coordinates indicating a plurality of regions included in the surface 1a of the ingot 1 on a coordinate plane parallel to the holding surface 21a.

[0033] Next, the excitation light source 23 irradiates the ingot 1 with excitation light A. When the excitation light A is irradiated onto the ingot 1 via the mirror 24 and the focusing lens 25, the ingot 1 absorbs the excitation light A and fluorescence B is generated at the focal point F1. For example, if the wavelength of the excitation light A is 365 nm, the excitation light A penetrates to a depth of about 10 μm from the surface 1a of the ingot 1. Then, fluorescence B is generated from a plate-like region on the surface 1a side of the ingot 1 with a thickness of about 10 μm. The fluorescence B generated at the focal point F1 reaches the filter 27 via the elliptical mirror 26. Then, only the light with wavelengths in the IR region (for example, wavelengths of 750 nm or more) of the fluorescence B is transmitted through the filter 27. As a result, the light receiving unit 28 receives the light with wavelengths in the IR region and generates an electrical signal indicating the number of photons. Furthermore, with the holding table 21 and the detection unit 22 moved relative to each of the remaining coordinates mentioned above, the excitation light source 23 irradiates the ingot 1 with excitation light A.

[0034] As a result, an electrical signal indicating the number of photons in the IR wavelength range is generated, equal to the number of coordinates. This number of photons decreases as the impurity concentration of ingot 1 increases. Therefore, the detection device 20 can identify regions where the impurity concentration of ingot 1 differs.

[0035] The detection device 20 described above acquires data on impurity concentration based on the number of photons of fluorescence B generated by excitation light A, but is not limited to this; data on impurity concentration may also be acquired based on the brightness of fluorescence B generated by excitation light A. Specifically, the light receiving unit 28 generates an electrical signal indicating the brightness of fluorescence B that has passed through the filter 27, and the control device 29 may acquire data on impurity concentration based on the magnitude of the brightness of the received fluorescence B.

[0036] Another example of the impurity concentration acquisition step S10 is to irradiate the ingot 1 with transparent light and acquire data on the impurity concentration based on the light transmittance. Regions with low light transmittance are identified as facet regions F with high impurity concentrations.

[0037] Three examples of the impurity concentration acquisition step S10 have been described above, but the data on impurity concentration may be acquired by any method, and the data is not limited to these. For example, the impurity concentration acquisition step S10 based on light transmittance may be performed during the peeling initiation point formation step S20, which will be described later.

[0038] The laser beam irradiation mechanism 30, which performs the delamination point formation step S20, irradiates the ingot 1 with a laser beam of a wavelength that penetrates the ingot 1, positioned at a depth below the surface 1a of the ingot 1. Generally, when the impurity concentration of the ingot 1 is high, the transmittance of the laser beam decreases, and the output of the laser beam required to form the delamination point 4 increases. Conversely, when the impurity concentration of the ingot 1 is low, the transmittance of the laser beam increases, and the output of the laser beam required to form the delamination point 4 decreases. That is, the transmittance of light in the ingot 1 can be determined based on the output of the laser beam required to form the delamination point 4 in the ingot 1. The impurity concentration acquisition step S10 may acquire data on the impurity concentration of the ingot 1 based on the light transmittance obtained in this way.

[0039] As mentioned above, the impurity concentration of ingot 1 differs depending on the position in the thickness direction, so the multiple wafers 2 that are peeled off each have different impurity concentration distributions and / or different average values ​​of impurity concentrations. Therefore, the impurity concentration acquisition step S10 is performed each time a predetermined number of wafers 2 (for example, 1 or 5) are peeled off from ingot 1. This makes it possible to accurately acquire the distribution of impurity concentration and / or the average value of impurity concentration for each wafer 2 in the impurity concentration acquisition step S10.

[0040] (Step to form a peeling initiation point) Figure 6 is a schematic diagram of the laser beam irradiation mechanism 30 that performs the peeling initiation step S20. The laser beam irradiation mechanism 30 irradiates the ingot 1, which is fixed to the holding table 31, with a laser beam from the surface 1a side to form a peeling initiation point 4 on the ingot 1.

[0041] More specifically, the laser beam irradiation mechanism 30 comprises a laser beam generation unit 32 and a light concentrator (laser head) 35. Although not shown in the diagram, an imaging unit, consisting of optical means such as a microscope or a CCD (Charge Coupled Device) camera, is attached to the laser beam irradiation mechanism 30 adjacent to the light concentrator 35.

[0042] The laser beam generation unit 32 includes a laser oscillator 33 that emits a YAG laser or a YVO4 laser, and an output adjustment unit 34. The laser oscillator 33 has a Brewster window, and the laser beam emitted from the laser oscillator 33 is a linearly polarized laser beam. The pulsed laser beam, adjusted to a predetermined power by the output adjustment unit 34 of the laser beam generation unit 32, is reflected by the mirror 36 of the focuser 35, and the focusing point is positioned inside the ingot 1 by the focusing lens 37 before irradiation. The surface 1a of the ingot 1 is polished to a mirror surface as it becomes the irradiation surface of the laser beam.

[0043] Figure 7 shows the state in which a laser beam is irradiated from the surface 1a of the ingot 1 by the laser beam irradiation mechanism 30. The laser beam irradiation mechanism 30 forms a peeling initiation point 4 containing multiple modification regions 5 inside the ingot 1.

[0044] More specifically, the laser beam irradiation mechanism 30 positions the focal point of a laser beam having a wavelength that penetrates the ingot 1 held by the holding table 31 at a position deeper than the surface 1a of the ingot 1, and forms a modified region 5 by focusing and irradiating the laser beam from the surface 1a of the ingot 1. The laser beam irradiation mechanism 30 then processes and feeds the ingot 1 so that the focal point moves from one end to the other along the X-axis to form a modified region 5 along the X-axis, and then indexes and feeds the ingot 1 by a predetermined amount in the Y-axis direction, and then processes and feeds the ingot 1 so that the focal point moves from the other end to the one end along the X-axis to form a modified region 5 along the X-axis, repeating this process. As a result, a delamination initiation point 4 including the modified region 5 and cracks extending from the modified region 5 is formed inside the ingot 1.

[0045] Thus, in the delamination initiation step S20, the laser beam irradiation mechanism 30 positions the focal point of the laser beam to a position deeper than the surface 1a of the ingot 1, and irradiates the ingot 1 with the laser beam from the surface 1a, thereby forming a delamination initiation point 4 including a modified region 5 and cracks extending from the modified region 5.

[0046] (Peeling step) Figures 8 and 9 are schematic diagrams of the peeling apparatus 40 that performs the peeling step S30. The peeling apparatus 40 comprises a disc-shaped holding table 41 that holds the ingot 1 with its surface 1a facing upwards, an ultrasonic oscillation unit 42 that applies ultrasonic waves to the ingot 1, and a peeling unit 46 that peels the wafer 2 from the ingot 1. Figure 6 shows the ultrasonic oscillation unit 42, and Figure 7 shows the peeling unit 46.

[0047] The holding table 41 holds the ingot 1, for example, via an epoxy resin adhesive, or holds the ingot 1 by suction force generated by a suction source (not shown). The holding table 41 is also rotatable around a central axis extending in a direction perpendicular to the holding surface 41a (vertical direction) by a spindle and motor, etc.

[0048] As shown in Figure 8, the ultrasonic oscillation unit 42 includes an ultrasonic transducer 43 having an end face 43a facing the surface 1a of the ingot 1 held on the holding table 41, which applies ultrasonic waves to the ingot 1, and a liquid supply nozzle 44 that supplies liquid (e.g., pure water) between the surface 1a of the ingot 1 and the end face 43a of the ultrasonic transducer 43. The ultrasonic transducer 43 and the liquid supply nozzle 44 are provided so as to be able to adjust their vertical position by a lifting mechanism such as an air cylinder, a ball screw, and a motor.

[0049] The ultrasonic transducer 43 is positioned so that there is a small gap (e.g., 0.6 mm) between its end face 43a and the surface 1a of the ingot 1. The liquid supply nozzle 44 continuously supplies liquid into the gap between the end face 43a of the ultrasonic transducer 43 and the surface 1a of the ingot 1 while applying ultrasound to the ingot 1, forming a liquid layer WL. The ultrasound emitted from the ultrasonic transducer 43 is transmitted to the ingot 1 through the liquid layer WL, causing the cracks at the delamination initiation point 4 formed in the ingot 1 to elongate. This reduces the strength of the delamination initiation point 4.

[0050] As shown in Figure 9, the peeling unit 46 has a suction pad 47 that sucks and holds the wafer 2 to be peeled off from the ingot 1. The suction pad 47 is provided so that its vertical position can be adjusted by a lifting mechanism such as an air cylinder, a ball screw, and a motor. After ultrasonic waves are applied to the entire surface 1a of the ingot 1, the peeling unit 46 moves to a position facing the holding table 41 at the same time as or after the ultrasonic oscillation unit 42 separates from the holding table 41. Then, the peeling unit 46 sucks the surface 1a of the ingot 1 onto the suction pad 47 and moves the suction pad 47 upward, thereby peeling the plate-like material including the surface 1a of the ingot 1 as a wafer 2 from the peeling starting point 4 of the ingot 1.

[0051] Thus, in the peeling step S30, the peeling device 40 peels the wafer 2 from the peeling starting point 4 of the ingot 1.

[0052] Figure 10 shows a modified example of the ultrasonic oscillation unit 42 of the peeling device 40. The modified ultrasonic oscillation unit 42 has a water tank 48 containing liquid, and the ultrasonic transducer 43 and the ingot 1 are placed in the liquid. That is, the ultrasonic waves irradiated from the ultrasonic transducer 43 are applied to the ingot 1 via the liquid stored in the water tank 48. Even with this configuration, it is possible to promote the extension of cracks at the peeling initiation point 4 formed in the ingot 1.

[0053] (Grinding step) Figure 11 is a perspective view of the grinding apparatus 50 performing the grinding step S40. The grinding apparatus 50 holds the wafer 2, which was peeled off in the peeling step S30, on the holding table 51 with the peeled surface 2a facing upwards, and grinds the exposed peeled surface 2a of the wafer 2 to flatten it.

[0054] The holding table 51 holds the ingot 1 placed on the holding surface 51a by suction using a suction source (not shown). The holding table 51 is rotatable about a central axis extending in a direction perpendicular to the holding surface 51a (vertical direction) by a spindle and motor, etc. The holding table 51 may also be movable along a direction parallel to the holding surface 51a (horizontal direction) and / or vertical direction.

[0055] Furthermore, the holding table 51 may be provided with a cooling passage (not shown) through which cooling water flows. The cooling water is not supplied directly to the wafer 2, but rather the temperature rise of the wafer 2 during processing is suppressed by heat exchange between the cooling water flowing through the cooling passage and the wafer 2.

[0056] The grinding device 50 includes a spindle 52 that extends vertically and is rotatable by a drive source such as a motor, a disc-shaped mount 53 fixed to the lower end of the spindle 52, and a grinding wheel 54 fixed to the lower end of the mount 53. The spindle 52 is mounted so as to be able to move vertically up and down relative to the holding table 51.

[0057] The grinding wheel 54 includes, for example, an annular wheel base 55 made of a metal material such as stainless steel or aluminum, and a plurality of grinding wheels 56 arranged in an annular pattern on the lower surface of the wheel base 55. The grinding wheels 56 include, for example, a binder made of ceramics, resin, metal material, etc., and countless abrasive grains such as diamond dispersed and fixed in the binder.

[0058] In grinding step S40, the peeled surface 2a of the wafer 2 held on the holding table 51 is ground with a grinding wheel 56. Grinding step S40 is performed, for example, by infeed grinding as shown in Figure 11. In infeed grinding, the positional relationship between the holding table 51 and the grinding wheel 54 is adjusted so that the center of the wafer 2 held on the holding table 51 coincides with the trajectory of the grinding wheel 56. Then, infeed grinding is performed by rotating the holding table 51 and the grinding wheel 54 respectively, while lowering the grinding wheel 54 along the processing feed direction (vertical direction) parallel to the rotation axis of the spindle 52. As a result, the lower surface of the grinding wheel 56 comes into contact with the upper surface (peeled surface 2a) of the wafer 2, and the wafer 2 is ground.

[0059] The grinding step S40 may be performed by creep feed grinding. In creep feed grinding, the positional relationship between the holding table 51 and the grinding wheel 54 is adjusted so that the grinding wheel 56 is positioned outside the wafer 2 and the lower surface of the grinding wheel 56 is positioned below the peeling surface 2a of the wafer 2. Creep feed grinding is performed by rotating the grinding wheel 54 and moving it along the processing feed direction (horizontal direction) parallel to the holding surface 51a of the holding table 51. As a result, mainly the side surface of the grinding wheel 56 comes into contact with the peeling surface 2a of the wafer 2, and the wafer 2 is ground.

[0060] (Polishing step) Figure 12 is a schematic diagram showing the configuration of the polishing apparatus 60 that performs the polishing step S50. The polishing apparatus 60 polishes and flattens the peeled surface 2a of the wafer 2 that was ground in the grinding step S40. Here, we will explain using the case where the holding table that holds the wafer 2 is the holding table 51 used in the grinding step S40 as an example.

[0061] The polishing apparatus 60 includes a rotational drive source 71 that has a motor and rotates the holding table 51 around a central axis extending vertically, and a tilt adjustment mechanism 72 that adjusts the tilt of the holding table 51. The tilt adjustment mechanism 72 consists of, for example, two movable support parts and one fixed support part, and supports the holding table 51 from below at three points. The tilt adjustment mechanism 72 adjusts the tilt of the holding table 51 by tilting the holding table 51 with the fixed support part as a fulcrum through the vertical movement of the two movable support parts.

[0062] The polishing apparatus 60 includes a spindle 62 that extends vertically and is rotatably mounted, a disc-shaped mount 63 fixed to the lower end of the spindle 62, a polishing pad 64 having a polishing surface and fixed to the lower end of the mount 63, a polishing agent supply source 65 that supplies polishing agent to the processing point when polishing the wafer 2 through a through hole 65a, a rotation drive source 66 having a motor that rotates the spindle 62, and a polishing feed mechanism 67 that raises and lowers the spindle 62 in the vertical direction.

[0063] The polishing pad 64 is formed in a disc shape that is larger than the holding surface 51a of the holding table 51. The polishing pad 64 is composed of a fixed abrasive layer in which abrasive grains are dispersed. The fixed abrasive layer is manufactured, for example, by impregnating a polyester nonwoven fabric with a urethane solution in which abrasive grains with an average particle size of 0.4 μm to 0.6 μm are dispersed, and then drying it. The abrasive grains dispersed inside the fixed abrasive layer consist of materials such as SiC, CBN, diamond, or metal oxide fine particles. As metal oxide fine particles, fine particles made of SiO2, CeO2, ZrO2, or Al2O3 are used. The fixed abrasive layer is also flexible and flexes slightly in response to the pressure applied when polishing the wafer 2. The polishing pad 64 is an example of a planarization processing part in the present invention.

[0064] Furthermore, the polishing pad 64 may be provided with a cooling channel (not shown) through which cooling water flows to cool the wafer 2. The cooling water is not supplied directly to the wafer 2, but rather the cooling water flowing through the cooling channel and the wafer 2 exchange heat, thereby suppressing the temperature rise of the wafer 2 during processing.

[0065] The radial centers of the spindle 62, mount 63, and polishing pad 64 are roughly coincidental, meaning their axes of rotation are roughly coincidental. The rotational drive source 66 rotates the spindle 62 around a vertically extending axis of rotation, thereby rotating the mount 63 and polishing pad 64, which are fixed to the lower end of the spindle 62. The polishing feed mechanism 67 raises and lowers the spindle 62 vertically, thereby moving the polishing pad 64 closer to or further away from the holding table 51 (wafer 2).

[0066] The polishing agent supply source 65 includes a storage tank and a liquid transfer pump for the polishing agent. During polishing, the polishing agent supply source 65 supplies the polishing agent to the processing point when polishing the wafer 2 through the through hole 65a. The through hole 65a is formed to penetrate the center of the spindle 62, the mount 63, and the polishing pad 64. The polishing agent is, for example, a slurry that oxidizes the surface of the wafer 2, and the polishing apparatus 60 polishes the wafer 2 by so-called chemical mechanical polishing (CMP). The polishing agent contains an oxidizing agent and a pH adjuster, and is, for example, a mixture of sodium permanganate and lanthanum nitrate. In this embodiment, the polishing pad 64 contains abrasive grains and the slurry does not contain abrasive grains, but the polishing pad 64 may not contain abrasive grains and the slurry may contain abrasive grains, or both the polishing pad 64 and the slurry may contain abrasive grains.

[0067] Furthermore, the polishing apparatus 60 further includes a control device 100 that controls the operation of the holding table 51 and the spindle 62. The control device 100 has a processor that performs calculations according to a program, and a memory such as ROM and RAM. The control device 100 is configured to receive data on impurity concentration acquired in the impurity concentration acquisition step S10. The control device 100 itself may be configured to acquire data on impurity concentration, that is, the control device 100 may have the functions of the control device 12 and the control device 29 described above.

[0068] The control device 100 transmits signals to the rotation drive source 71 and / or the tilt adjustment mechanism 72 to control the operation of the holding table 51. Specifically, the control device 100 adjusts the rotation speed, tilt, etc., of the holding table 51.

[0069] The control device 100 transmits signals to the rotational drive source 66 and / or the polishing feed mechanism 67 to control the operation of the spindle 62. Specifically, the control device 100 adjusts the rotational speed of the spindle 62 (polishing pad 64), the processing feed amount, the processing feed rate (polishing rate, described later), etc.

[0070] Furthermore, the polishing device 60 may also include a tilt adjustment mechanism for adjusting the tilt of the polishing pad 64, in place of or in addition to the tilt adjustment mechanism 72 for adjusting the tilt of the holding table 51. The control device 100 may send a signal to this tilt adjustment mechanism to adjust the tilt of the polishing pad 64 relative to the holding table 51.

[0071] In the polishing step S50, the holding table 51 and the spindle 62 are rotated while the spindle 62 is lowered so that the polishing pad 64 comes into contact with the peeled surface 2a of the wafer 2, and the peeled surface 2a of the wafer 2 is polished by the polishing pad 64.

[0072] Incidentally, when polishing a workpiece (wafer 2) doped with impurities, the polishing rate (amount of material processed per unit time) by the polishing device 60 changes depending on the impurity concentration. For example, when polishing a Si single crystal wafer 2, the higher the impurity concentration of wafer 2, the lower the polishing rate. A lower polishing rate increases the polishing time, so the edges of wafer 2, which are more susceptible to pressure from the polishing pad 64, become thinner than necessary. Furthermore, this relationship between impurity concentration and polishing rate differs depending on the material of wafer 2 and the type of impurities being doped. For example, when polishing a SiC single crystal wafer 2 doped with nitrogen, the higher the impurity concentration of wafer 2, the higher the polishing rate. In this way, the polishing rate changes depending on the impurity concentration of wafer 2, and as a result, the thickness of wafer 2 after polishing becomes uneven.

[0073] Therefore, in the polishing step S50, the peeled surface 2a of the wafer 2 is polished and flattened based on the data regarding the impurity concentration obtained in the impurity concentration acquisition step S10.

[0074] To illustrate with an example, in the polishing step S50, the contact conditions of the polishing pad 64 with the wafer 2 are changed based on the average value of the impurity concentration, which is the data on impurity concentration obtained in the impurity concentration acquisition step S10.

[0075] The contact conditions include, for example, at least one of the following: the rotational speed of at least one of the polishing pad 64 and the holding table 51; the inclination of at least one of the polishing pad 64 and the holding table 51; the contact time (i.e., polishing time) during which the polishing pad 64 is in contact with the wafer 2; and the pressing force of the polishing pad 64 against the wafer 2. The control device 100 changes at least one of these rotational speed, inclination, contact time, and pressing force based on the average value of the impurity concentration of the wafer 2 to be polished, so that the thickness of the wafer 2 becomes uniform.

[0076] Furthermore, the contact conditions may include, in addition to or in addition to, the conditions described above, at least one of the following: the temperature of the cooling water at the processing point, the temperature of the polishing agent supplied from the polishing agent supply source 65, and the composition of the polishing agent. The cooling water at the processing point is the cooling water flowing through the cooling channels provided in the holding table 51 and polishing pad 64 as described above. The control device 100 changes at least one of the cooling water temperature, the polishing agent temperature, and the composition of the polishing agent based on the average value of the impurity concentration of the wafer 2 to be polished, so that the thickness of the wafer 2 becomes uniform. One example of changing the composition of the polishing agent as a contact condition is adjusting the concentration of the oxidizing agent or pH adjuster contained in the polishing agent.

[0077] The control device 100 may obtain the aforementioned rotational speed, tilt, contact time, pressing force, cooling water temperature, abrasive temperature, and abrasive composition by calculating them based on the average value of the impurity concentration, or by referring to a predetermined map stored in advance.

[0078] In polishing step S50, the contact conditions of the polishing pad 64 with the wafer 2 may be changed based on the distribution of impurity concentrations rather than the average value of the impurity concentration, as data regarding the impurity concentration. That is, in polishing step S50, the contact conditions may be changed so that at least one of the aforementioned rotation speed, inclination, contact time, pressing force, cooling water temperature, polishing agent temperature, and polishing agent composition differs between regions with high impurity concentrations and regions with low impurity concentrations.

[0079] To give a specific example, the polishing step S50 may polish the peeled surface 2a of the wafer 2 by applying a predetermined pressure distribution to the pressing force from the polishing pad 64 to the wafer 2 based on the distribution of impurity concentrations. For example, the polishing apparatus 60 further has an airbag that provides a distribution to the pressing force, and by partially changing the air pressure of the airbag, a predetermined pressure distribution is applied to the pressing force from the polishing pad 64 to the wafer 2.

[0080] Another example is that in polishing step S50, a temperature distribution may be added to the cooling water flowing through the cooling channels provided in the polishing pad 64 and / or the holding table 51 based on the distribution of impurity concentrations, thereby polishing the peeled surface 2a of the wafer 2. For example, multiple cooling channels may be provided, and cooling water at different temperatures may be circulated between the cooling channel corresponding to the high impurity concentration region of the wafer 2 and the cooling channel corresponding to the low impurity concentration region. Alternatively, a temperature distribution may be added to the cooling water by circulating the cooling water from the cooling channel corresponding to the high impurity concentration region of the wafer 2 to the cooling channel corresponding to the low impurity concentration region (or in the reverse order).

[0081] Thus, the polishing step S50 polishes and flattens the peeled surface 2a of the wafer 2 based on data regarding impurity concentration, thereby reducing variations in the thickness of the wafer 2 during the polishing step S50. As a result, the thickness of the manufactured wafer 2 can be made uniform.

[0082] [Second Embodiment] Next, a processing method according to a second embodiment of the present invention will be described.

[0083] Figure 13 is a flowchart of the processing method of the second embodiment. The processing method of the second embodiment includes an impurity concentration acquisition step S10, a peeling initiation point formation step S20, a peeling step S30, a grinding step S40, a shaping step S45 in which the shape of the polishing pad 64 is shaped based on the distribution of impurity concentrations, which is data acquired in the impurity concentration acquisition step S10, and a polishing step S50 in which the polishing pad 64 shaped in the shaping step S45 is brought into contact with the peeling surface 2a of the ground wafer 2 and polished. The impurity concentration acquisition step S10, the peeling initiation point formation step S20, the peeling step S30, and the grinding step S40 are the same as in the first embodiment, and repeated explanations are omitted.

[0084] (Shaping steps) Figure 14 is a schematic diagram showing the configuration of the dressing mechanism 80 that performs the shaping step S45. The dressing mechanism 80 shapes the shape of the polishing surface of the polishing pad 64 before the polishing step S50.

[0085] The dressing mechanism 80 includes a dressing unit 81 for shaping the polishing surface of the polishing pad 64, a lifting mechanism 87 for raising and lowering the dressing unit 81 in the vertical direction, a displacement measuring instrument 88 for measuring the vertical displacement of the dressing unit 81 by the lifting mechanism 87, and a radial movement mechanism 89 for moving the dressing unit 81 along the radial direction of the polishing pad 64.

[0086] The dressing unit 81 includes a spindle 82 that extends vertically and is rotatably mounted, a mount 83 fixed to the upper end of the spindle 62, a disc-shaped dressing plate 84 fixed to the upper end of the mount 83, and a rotational drive source 86 having a motor that rotates the spindle 82.

[0087] The dress plate 84 is formed by adhering particles such as diamonds to its surface. The dress plate 84 has a disc shape with a smaller diameter than the polishing pad 64 and is provided opposite to the polishing pad 64 when the polishing pad 64 is being shaped.

[0088] The radial center positions of the spindle 82, mount 83, and dress plate 84 are roughly coincidental, meaning their axes of rotation are roughly coincidental. The rotational drive source 86 rotates the spindle 82, thereby rotating the mount 83 and dress plate 84, which are fixed to the upper end of the spindle 82.

[0089] The lifting mechanism 87 is composed of a ball screw and a motor, etc. By raising and lowering the dressing unit 81 in the vertical direction, the dressing plate 84 is brought closer to or further away from the polishing pad 64.

[0090] The radial movement mechanism 89 is configured with a ball screw and a motor, etc. The radial movement mechanism 89 moves the dressing unit 81 along the radial direction of the polishing pad 64. This makes it possible to change the radial contact position between the dressing plate 84 and the polishing pad 64.

[0091] The control device 100 is configured to control the dressing mechanism 80 in addition to the polishing device 60. The control device 100 controls the rotary drive source 86, the lifting mechanism 87, and / or the radial movement mechanism 89, and controls the operation of the dressing plate 84. When the control device 100 controls the dressing mechanism 80, it may also control the polishing device 60 at the same time.

[0092] The dressing mechanism 80 may further include a tilt adjustment mechanism for adjusting the tilt of the dressing plate 84. The control device 100 may then control the tilt adjustment mechanism to adjust the tilt of the dressing plate 84.

[0093] First, the shaping step S45 involves rotating the dressing plate 84 and the polishing pad 64 while bringing them into contact. Specifically, the control device 100 controls the lifting mechanism 87 of the dressing mechanism 80 to bring the dressing plate 84 closer to the polishing pad 64. Alternatively, the control device 100 may control the polishing feed mechanism 67 of the polishing device 60 to bring the polishing pad 64 closer to the dressing plate 84, or it may control both the polishing feed mechanism 67 and the lifting mechanism 87 to bring the dressing plate 84 and the polishing pad 64 closer together.

[0094] Next, in the shaping step S45, the dressing plate 84 and the polishing pad 64 are moved relative to each other in the radial direction while in contact with each other. Specifically, the control device 100 controls the radial movement mechanism 89 of the dressing mechanism 80 to move the dressing plate 84 radially relative to the polishing pad 64. If the polishing pad 64 is configured to move radially, the control device 100 may move the polishing pad 64 radially relative to the dressing plate 84.

[0095] As mentioned above, when polishing a workpiece (wafer 2) doped with impurities, the polishing rate by the polishing apparatus 60 changes depending on the impurity concentration. For example, in areas of the SiC single crystal wafer 2 with a high impurity concentration (faceted areas F), the polishing rate is higher compared to areas of the wafer 2 with a low impurity concentration (non-faceted areas). Therefore, when polishing wafer 2 with a flat polishing pad 64, there is a risk that the faceted areas F will become thinner than necessary compared to the non-faceted areas. As a result, the thickness of the wafer 2 after polishing will not be uniform.

[0096] Therefore, the shaping step S45, prior to the polishing step S50, shapes the polishing pad 64 based on the distribution of impurity concentrations, which is data obtained from the impurity concentration.

[0097] Figure 15 is a schematic diagram showing an example of a shaped polishing pad 64. Note that the shape of the polishing pad 64 is exaggerated compared to the actual thickness of the polishing pad 64.

[0098] In shaping step S45, the polishing pad 64 is shaped so that the amount of protrusion toward the wafer 2 differs between the portion that contacts the facet region F of the wafer 2 and the portion that contacts the non-facet region. Specifically, in the case of a SiC single crystal wafer 2, shaping step S45 shapes the polishing pad 64 so that the portion that contacts the non-facet region of the wafer 2 protrudes toward the wafer 2 more than the portion that contacts the facet region F. In the example shown here, the facet region F is formed in the center of the wafer 2, and the non-facet region is formed radially outward from the facet region F. The polishing process is performed with the rotation axis of the polishing pad 64 and the rotation axis of the holding table 51 misaligned.

[0099] Furthermore, in the case of a Si single-crystal wafer 2, the polishing rate is lower in the facet region F of wafer 2 compared to the non-facet region of wafer 2. Therefore, as shown in Figure 16, the shaping step S45 shapes the polishing pad 64 so that the portion that contacts the facet region F of the Si single-crystal wafer 2 protrudes more towards the wafer 2 than the portion that contacts the non-facet region.

[0100] Due to the shape of the polishing pad 64, the polishing pad 64 contacts the areas where the polishing rate is lower first, thus preventing variations in the thickness of the wafer 2 between the faceted areas F and the non-faceted areas.

[0101] (Polishing step) In the polishing step S50, the polishing pad 64, which was shaped in the shaping step S45, is brought into contact with the peeled surface 2a of the wafer 2 and polished to flatten it.

[0102] Thus, in the second embodiment as well, the polishing step S50 polishes and flattens the peeled surface 2a of the wafer 2 based on data regarding the impurity concentration, thereby reducing variations in the thickness of the wafer 2 in the polishing step S50. As a result, the thickness of the manufactured wafer 2 can be made uniform.

[0103] Although embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0104] For example, the processing methods of each embodiment described above show an example in which the polishing step S50 is performed based on data relating to the impurity concentration of wafer 2, but are not limited to this. For example, the processing method may also include a grinding step S40 based on data relating to the impurity concentration of wafer 2. That is, the grinding step S40 may be performed by grinding the peeled surface 2a of wafer 2 to flatten it based on the data relating to the impurity concentration of wafer 2 obtained in the impurity concentration acquisition step S10. In this case, the grinding wheel 56 is an example of the flattening processing part in the present invention. The data used in the grinding step S40 similarly includes the average value of the impurity concentration and / or the distribution of the impurity concentration.

[0105] More specifically, the grinding step S40 may change the contact conditions with the wafer 2 based on the data regarding the impurity concentration obtained in the impurity concentration acquisition step S10. The contact conditions include, for example, at least one of the following: the rotational speed of at least one of the grinding wheel 56 and the holding table 51, the inclination of at least one of the grinding wheel 56 and the holding table 51, the feed rate at which the grinding wheel 56 cuts into the wafer 2, and the temperature of the cooling water.

[0106] For example, in the embodiments described above, the impurity concentration acquisition step S10 was performed on the ingot 1, but it is not limited to this and may also be performed on the wafer 2 that has been peeled off from the ingot 1. That is, the impurity concentration acquisition step S10 may be performed after the peeling step S30.

[0107] Furthermore, in the embodiments described above, the wafer 2 was peeled from the ingot 1 by the laser beam irradiation mechanism 30 and the peeling device 40, but this is not limited to this. For example, the wafer 2 may be obtained by slicing the ingot 1 to a predetermined thickness using a wire saw. In this case, the impurity concentration acquisition step S10 may be performed on the wafer 2 obtained from the ingot 1 using the wire saw.

[0108] This specification includes at least the following: The components and other elements corresponding to each embodiment described above are shown in parentheses as examples, but are not limited thereto.

[0109] (1) An impurity concentration acquisition step (impurity concentration acquisition step S10) is performed to acquire data on the impurity concentration of the workpiece (ingot 1, wafer 2), A processing method comprising: a flattening step (grinding step S40, polishing step S50) in which one surface (peeling surface 2a) of the workpiece held on a holding table (holding table 51) is flattened by grinding or polishing with a flattening processing unit (grinding wheel 56, polishing pad 64), The planarization step planarizes one surface of the workpiece based on the data obtained in the impurity concentration acquisition step. Processing method.

[0110] When flattening a workpiece that has been pre-doped with impurities, the flattening rate in the flattening step changes depending on the impurity concentration, and the workpiece may not be flattened to a uniform thickness. According to (1), the flattening step flattens one surface of the workpiece based on the data on impurity concentration obtained in the impurity concentration acquisition step, so variations in the thickness of the workpiece can be reduced in the flattening step.

[0111] (2) The processing method described in (1), The planarization step involves changing the contact conditions of the planarization section with the workpiece based on the data obtained in the impurity concentration acquisition step. Processing method.

[0112] According to (2), the variation in the thickness of the workpiece can be reduced in the planarization step by changing the contact conditions with the workpiece based on the data obtained in the impurity concentration acquisition step.

[0113] (3) The processing method described in (2), The aforementioned contact conditions are: The rotational speed of at least one of the flattening section and the holding table, The inclination of at least one of the flattening section and the holding table, The contact time during which the flattening section and the workpiece are in contact, The pressing force applied to the workpiece by the flattening portion, The temperature of the cooling water flowing through a cooling channel provided in the flattening section and / or the holding table, which is capable of cooling the processing point of the workpiece, The temperature of the abrasive supplied to the processing point, and The composition of the abrasive supplied to the processing point includes at least one of the following: Processing method.

[0114] According to (3), by appropriately changing the contact conditions, variations in the thickness of the workpiece can be reduced in the planarization step.

[0115] (4) The processing method described in (2) or (3), The data obtained in the aforementioned impurity concentration acquisition step is the average value of the impurity concentration of the workpiece. Processing method.

[0116] According to (4), variations in the thickness of the workpiece can be reduced in the planarization step by changing the contact conditions based on the average value of the impurity concentration of the workpiece.

[0117] (5) The processing method described in (1), The planarization step is a polishing step (polishing step S50) in which one surface of the workpiece is polished with a polishing pad (polishing pad 64), The polishing step applies a predetermined pressure distribution to the pressing force from the polishing pad to the workpiece based on the distribution of impurity concentrations, which is the data obtained in the impurity concentration acquisition step, and flattens one surface of the workpiece. Processing method.

[0118] The polishing rate differs between areas with high and low impurity concentrations in the workpiece. According to (5), by changing the pressing force from the polishing pad to the workpiece between areas with high and low impurity concentrations, variations in the thickness of the workpiece can be reduced.

[0119] (6) The processing method described in (1), The planarization step, based on the distribution of impurity concentrations which is the data obtained in the impurity concentration acquisition step, provides a temperature distribution to the cooling water flowing through a plurality of cooling channels provided in the planarization processing unit and / or the holding table, which are capable of cooling the processing point of the workpiece, and flattens one surface of the workpiece. Processing method.

[0120] According to (6), variations in the thickness of the workpiece can be reduced by changing the temperature of the cooling water between regions with high and low impurity concentrations.

[0121] (7) The processing method described in (1), The planarization step is a polishing step (polishing step S50) in which one surface of the workpiece is polished with a polishing pad (polishing pad 64), The aforementioned processing method is Prior to the polishing step, the polishing pad is further shaped (shaping step S45) based on the distribution of impurity concentrations, which is the data obtained in the impurity concentration acquisition step. The polishing step involves polishing one surface of the workpiece with the polishing pad shaped in the shaping step. Processing method.

[0122] The polishing rate differs between areas of high and low impurity concentration in the workpiece. According to (7), the shape of the polishing pad can be shaped based on the distribution of impurity concentration, so that the shape of the polishing pad for polishing areas with high impurity concentration is different from the shape of the polishing pad for polishing areas with low impurity concentration. Therefore, the workpiece can be polished to a uniform thickness in the polishing step.

[0123] (8) The processing method described in (7), The shaping step involves shaping the polishing pad so that the amount of protrusion toward the workpiece differs between the portion that contacts the area of ​​the workpiece with a high impurity concentration (faceted area F) and the portion that contacts the area of ​​the workpiece with a low impurity concentration (non-faceted area). Processing method.

[0124] According to (8), the shaping step shapes the polishing pad so that the amount of protrusion of the polishing pad differs between the part that contacts the area of ​​the workpiece with a high impurity concentration and the part that contacts the area with a low impurity concentration, so that the workpiece can be polished to a uniform thickness in the polishing step.

[0125] (9) A processing method described in any of (1) to (8), The impurity concentration acquisition step involves measuring the electrical resistance of the workpiece and acquiring data on the impurity concentration based on the electrical resistance. Processing method.

[0126] According to (9), data on the impurity concentration of a workpiece can be obtained by utilizing the electrical resistance value of the workpiece, which differs depending on the impurity concentration.

[0127] (10) A processing method described in any of (1) to (8), The impurity concentration acquisition step involves irradiating the workpiece with excitation light of a predetermined wavelength and acquiring data on the impurity concentration based on a predetermined detection result of fluorescence generated by the excitation light. Processing method.

[0128] According to (10), data on the impurity concentration of a workpiece can be obtained by utilizing the fluorescence produced when the workpiece is irradiated with excitation light.

[0129] (11) A processing method described in any of (1) to (8), The impurity concentration acquisition step involves irradiating the workpiece with light that has transparency and acquiring data on the impurity concentration based on the light transmittance. Processing method.

[0130] According to (11), data on the impurity concentration of the workpiece can be obtained by utilizing the light transmittance to the workpiece.

[0131] (12) A processing apparatus (grinding apparatus 50, polishing apparatus 60) for processing one side (peeling surface 2a) of a workpiece (wafer 2) held on a holding table (holding table 51), Spindles (spindle 52, spindle 62) extending in a predetermined direction and rotatably mounted, Mounts (mount 53, mount 63) fixed to the tip of the spindle, The flattening section (grinding wheel 56, polishing pad 64) is fixed to the mount and grinds or polishes one surface of the workpiece to make it flat, The processing apparatus, based on data relating to the impurity concentration of the workpiece, flattens one surface of the workpiece in the planarization section. Processing equipment.

[0132] When flattening a workpiece that has been pre-doped with impurities, the flattening rate changes depending on the impurity concentration, and the workpiece may not be flattened to a uniform thickness. According to (12), the processing device flattens one surface of the workpiece based on data regarding the impurity concentration of the workpiece, thus reducing variations in the thickness of the workpiece.

[0133] (13) The processing apparatus described in (12), The processing apparatus changes the contact conditions of the planarization section with the workpiece based on data relating to the impurity concentration of the workpiece. Processing equipment.

[0134] According to (13), by changing the contact conditions with the workpiece based on data regarding impurity concentration, variations in the thickness of the workpiece can be reduced when flattening the workpiece.

[0135] (14) The processing apparatus described in (12), A polishing device (polishing device 60) comprising the spindle, the mount, and the polishing pad (polishing pad 64) which is the flattening part, The system includes a dressing mechanism (dressing mechanism 80) that shapes the polishing pad based on data relating to the impurity concentration of the workpiece, The polishing apparatus polishes one surface of the workpiece with the polishing pad shaped by the dressing mechanism. Processing equipment.

[0136] The polishing rate differs between areas of high and low impurity concentration in the workpiece. According to (12), the shape of the polishing pad can be shaped based on the distribution of impurity concentration, so that the shape of the polishing pad for polishing areas with high impurity concentration is different from the shape of the polishing pad for polishing areas with low impurity concentration. Therefore, the polishing device can polish the workpiece to a uniform thickness.

[0137] The processing apparatus described in (10) to (12) above corresponds to the polishing apparatus 60, grinding apparatus 50, or apparatus combining the polishing apparatus 60 and the dressing mechanism 80 in each of the embodiments described above. [Explanation of Symbols]

[0138] 1. Ingot (workpiece) 2. Wafer (workpiece) 50 Grinding equipment (processing equipment) 51 Holding Table 52 spindles 53 Mount 56 Grinding wheel (flattening part) 60 Polishing equipment (processing equipment) 62 spindles 63 Mount 64. Polishing pad (flattening section) 80 Dressing mechanism (processing device) S10 Step to obtain impurity concentration S40 Grinding step (flattening step) S45 Shaping Step S50 Polishing step (flattening step)

Claims

1. An impurity concentration acquisition step to obtain data on the impurity concentration of the workpiece, A processing method comprising: a flattening step of flattening one surface of the workpiece held on a holding table by grinding or polishing it in a flattening section, The planarization step planarizes one surface of the workpiece based on the data obtained in the impurity concentration acquisition step. Processing method.

2. The processing method according to claim 1, The planarization step involves changing the contact conditions of the planarization section with the workpiece based on the data obtained in the impurity concentration acquisition step. Processing method.

3. The processing method according to claim 2, The aforementioned contact conditions are: The rotational speed of at least one of the flattening section and the holding table, The inclination of at least one of the flattening section and the holding table, The contact time during which the flattening section and the workpiece are in contact, The pressing force applied to the workpiece by the flattening portion, The temperature of the cooling water flowing through a cooling channel provided in the flattening section and / or the holding table, which is capable of cooling the processing point of the workpiece, The temperature of the abrasive supplied to the processing point, and The composition of the abrasive supplied to the processing point includes at least one of the following: Processing method.

4. The processing method according to claim 2, The data obtained in the aforementioned impurity concentration acquisition step is the average value of the impurity concentration of the workpiece. Processing method.

5. The processing method according to claim 1, The planarization step is a polishing step in which one surface of the workpiece is polished with a polishing pad, The polishing step applies a predetermined pressure distribution to the pressing force from the polishing pad to the workpiece based on the distribution of impurity concentrations, which is the data obtained in the impurity concentration acquisition step, and flattens one surface of the workpiece. Processing method.

6. The processing method according to claim 1, The planarization step, based on the distribution of impurity concentrations which is the data obtained in the impurity concentration acquisition step, provides a temperature distribution to the cooling water flowing through a plurality of cooling channels provided in the planarization processing unit and / or the holding table, which are capable of cooling the processing point of the workpiece, and flattens one surface of the workpiece. Processing method.

7. The processing method according to claim 1, The planarization step is a polishing step in which one surface of the workpiece is polished with a polishing pad, The aforementioned processing method is Prior to the polishing step, the polishing pad is further shaped based on the distribution of impurity concentrations, which is the data obtained in the impurity concentration acquisition step. The polishing step involves polishing one surface of the workpiece with the polishing pad shaped in the shaping step. Processing method.

8. The processing method according to claim 7, The shaping step involves shaping the polishing pad so that the amount of protrusion toward the workpiece differs between the portion that contacts the area of ​​the workpiece with a high impurity concentration and the portion that contacts the area of ​​the workpiece with a low impurity concentration. Processing method.

9. A processing method according to any one of claims 1 to 8, The impurity concentration acquisition step involves measuring the electrical resistance of the workpiece and acquiring data on the impurity concentration based on the electrical resistance. Processing method.

10. A processing method according to any one of claims 1 to 8, The impurity concentration acquisition step involves irradiating the workpiece with excitation light of a predetermined wavelength and acquiring data on the impurity concentration based on a predetermined detection result of fluorescence generated by the excitation light. Processing method.

11. A processing method according to any one of claims 1 to 8, The impurity concentration acquisition step involves irradiating the workpiece with light that has transparency and acquiring data on the impurity concentration based on the light transmittance. Processing method.

12. A processing apparatus for processing one side of a workpiece held on a holding table, A spindle that extends in a predetermined direction and is rotatably mounted, A mount fixed to the tip of the spindle, The system includes a flattening section fixed to the mount, which grinds or polishes one surface of the workpiece to make it flat, The processing apparatus, based on data relating to the impurity concentration of the workpiece, flattens one surface of the workpiece in the planarization section. Processing equipment.

13. A processing apparatus according to claim 12, The processing apparatus changes the contact conditions of the planarization section with the workpiece based on data relating to the impurity concentration of the workpiece. Processing equipment.

14. A processing apparatus according to claim 12, A polishing apparatus comprising the spindle, the mount, and the polishing pad which is the flattening part, The system includes a dressing mechanism that shapes the polishing pad based on data relating to the impurity concentration of the workpiece, The polishing apparatus polishes one surface of the workpiece with the polishing pad shaped by the dressing mechanism. Processing equipment.

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