Apparatus and method for grinding and repairing the surface of a silicon wafer

Abstract

To provide a device and a method capable of grinding the surface of a silicon wafer and efficiently and effectively repairing a processed altered layer and flattening the roughness by using a pulse laser.SOLUTION: A grinding repair device (1) according to the present invention includes a wafer feed unit (20) that holds a silicon wafer (W) such that the silicon wafer can rotate, move, and / or tilt, a grinding unit (10) that grinds the surface of the silicon wafer, and a laser irradiation repair device (100) that irradiates the ground surface of the silicon wafer with laser, and the laser irradiation repair device (100) includes a measuring device (102) that measures the surface condition and / or shape of the silicon wafer, a laser irradiation unit (101) that irradiates the ground surface of the silicon wafer with laser, a displacement mechanism (120), and a control device (103) that controls an irradiation condition and / or irradiation atmosphere of the laser on the basis of measurement data of the measuring device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for grinding the surfaces of various materials such as silicon, sapphire, zirconia, glass, etc., particularly plate-shaped workpieces such as semiconductor wafers and glass panels (referred to as "silicon wafers" in this application), repairing and flattening the surface roughness caused by grinding marks, and repairing layers that have been damaged by processing (such as returning to single crystal), and in particular to an apparatus that can efficiently perform such repair operations by irradiating a laser. In particular, the present invention provides a technology suitable for suppressing damage such as the development of cracks in later processes by irradiating a laser onto the surface of the outer peripheral edge and notch of a silicon wafer after grinding, thereby improving the surface by repairing roughness and layers that have been damaged by processing. [Background technology]

[0002] In recent years, there has been a strong demand for improved wafer quality, and the processing state of the wafer end face (edge ​​portion) and notch portion is considered important, and semiconductor wafers such as silicon wafers used for manufacturing semiconductor devices, etc. are chamfered by grinding the edges, etc., and polished to a mirror finish to prevent chipping during handling. In other words, in the semiconductor manufacturing process, from wafer manufacturing to device manufacturing, quality improvement of edge characteristics has become an essential process.

[0003] Silicon and other materials are hard and brittle, and if the edges of the wafers remain sharp after slicing, they can easily crack or chip during handling in subsequent processing steps such as transportation and alignment, and the resulting fragments can damage or contaminate the wafer surface. To prevent this, the edges and notches of the sliced ​​wafers are chamfered with a diamond-coated chamfering grinding wheel.

[0004] In addition, thin, lightweight glass substrates for smartphones and tablets are masked and printed, and sensor electrodes are then formed on the substrate before being cut. During this process, the quality of the chamfering, the roughness of the machined surface, and the occurrence of microcracks all have a direct impact on the edge strength of the glass substrate.

[0005] The following Patent Documents 1, 2, and 3 disclose improved techniques for such wafer chamfering. That is, Patent Document 1 discloses a wafer edge processing device capable of processing the peripheral edge of a silicon wafer or the like into a shape with high precision using an abrasive tape. Patent Document 2 discloses a chamfering device capable of improving processing precision by eliminating bending deformation of the wafer that occurs when the peripheral edge of the wafer is helical ground. Patent Document 3 discloses a chamfering method capable of obtaining good processed surface roughness in chamfering the notch portion of a notched wafer.

[0006] After grinding the outer peripheral edge or notch of the silicon wafer as described above, the surface has been conventionally buffed to remove the grinding marks and smooth the surface, but the ground surface has cracks and processing distortion, and since the surface parts that have become amorphous cannot be completely removed, cracks and the like will grow from such parts of the wafer in the later process, resulting in damage and a decrease in yield. In addition, the polishing pressure (load) during buffing may expand the processing distortion and crystal transition.

[0007] In addition, because buff polishing is a polishing process (removal process) that removes material, when comparing the dimensions immediately after grinding with those after subsequent buff polishing, the dimensions after buff polishing will change to some extent. In addition, buff polishing requires consumables such as polishing thread, polishing liquid, and chemicals, as well as processes such as cleaning (removal of foreign matter) and drying after polishing, which are costly.

[0008] Unlike the mechanical surface repair processes described above, Patent Document 4 discloses a method for repairing surface defects by irradiating a laser on a process-affected layer on the surface caused by grinding a single crystal wafer. However, existing surface modification by laser irradiation is for simple flat surfaces, and does not involve irradiation under conditions according to complex shapes or various surface states after grinding, or irradiation while monitoring the irradiation results, making it difficult to achieve high-speed and effective processing. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5700264 [Patent Document 2] JP 2017-159421 A [Patent Document 3] JP 2005-153129 A [Patent Document 4] JP 2008-147639 A Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, when using conventional methods for repairing the surface condition of a silicon wafer after grinding, there were problems such as, in the case of buff polishing, surface defects could not be completely repaired or the original dimensions could not be strictly maintained, resulting in poor yields (especially in notches) and high costs, and in the case of laser irradiation, quick and effective repair results according to the surface condition and shape after grinding could not be obtained.

[0011] In consideration of these problems, an object of the present invention is to provide an apparatus and method for performing grinding on a workpiece (referred to as a "silicon wafer" in this application) and repairing processing damage by irradiating the grinding end area with a pulse laser (referred to as a "laser" in this application) with a pulse width at the nanosecond level.

[0012] More specifically, an object of the present invention is to provide a technique for repairing (converting to single crystallization, etc.) and improving roughness (flattening) of processing-damaged layers, particularly in the peripheral edge portion and / or notch portion of a silicon wafer.

[0013] Another object of the present invention is to provide a method and apparatus for diagnosing the extent and condition of a damaged area and for carrying out effective irradiation.

[0014] Furthermore, another object of the present invention is to provide an efficient laser irradiation method and apparatus that can be adapted to the shapes of edge portions and notches having different shapes.

[0015] In other words, an object of the present invention is to perform efficient surface treatment using a laser in a short time (for example, 10 seconds or less in the case of repairing a chamfered portion), thereby improving product throughput.

[0016] Therefore, another object of the present invention is to enable efficient and effective surface modification by checking the surface condition and shape of the silicon wafer to be repaired before, during and / or after laser irradiation, and irradiating the laser under conditions appropriate to the state of distortion, damage, etc.

[0017] Another object of the present invention is to completely repair cracks and distortions, improve the mechanical strength of the object to be repaired, and increase the yield of subsequent processes.

[0018] Another object of the present invention is to achieve a process that has a small environmental impact by eliminating the need for consumables such as abrasive thread, abrasive liquid, and chemicals, as well as cleaning and drying processes.

[0019] Another object of the present invention is to enable a simple process that can be carried out in an environment such as atmospheric pressure and room temperature, and does not require any additional raw materials.

[0020] Another object of the present invention is to enable repairs that maintain the original dimensions (precision) by modifying the material to be repaired (processed material) through heat treatment without removing the material. [Means for solving the problem]

[0021] In order to achieve the above object, the present invention is configured as follows. [1] A grinding repair device for a silicon wafer surface, comprising: a grinding unit that grinds the surface of a silicon wafer; and a laser irradiation repair device that irradiates a laser onto the ground surface of the silicon wafer in order to repair the surface of the silicon wafer, wherein the laser irradiation repair device controls the laser irradiation conditions and / or irradiation atmosphere based on measurement data obtained by measuring the surface condition and / or shape of the silicon wafer, and irradiates a laser onto the chamfered outer peripheral edge portion and / or notch portion of the silicon wafer after grinding. [2] The silicon wafer surface grinding repair device described in [1], characterized in that the measurement data is measured by any one or a combination of two or more selected from the group consisting of image measurement means, capacitance change measurement means, droplet contact angle measurement means, Raman spectroscopy measurement means, surface roughness meter, acoustic measurement means, eddy current characteristic measurement means, reflectivity measurement means, X-ray Lang's method measurement means, electron beam diffraction measurement means, and SEM measurement means. [3] The laser irradiation repair device is a grinding repair device for a silicon wafer surface described in [1] or [2], characterized in that, in addition to a laser light source, it has an optical mechanism including at least one of a mirror, a galvanometer mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, and a mask, and the laser irradiation conditions can be changed by the optical mechanism. [4] A grinding repair method for a silicon wafer surface, which is applied to a grinding repair device comprising a grinding unit that grinds the surface of a silicon wafer, and a laser irradiation repair device that irradiates a laser onto the ground surface of the silicon wafer in order to repair the surface of the silicon wafer, characterized in that the laser irradiation conditions and / or irradiation atmosphere are controlled based on measurement data obtained by measuring the surface condition and / or shape of the silicon wafer, and a laser is irradiated onto the chamfered outer peripheral edge portion and / or notch portion of the silicon wafer after grinding.

[0022] Another embodiment of the present invention relates to a silicon wafer surface grinding and repairing device, which includes a wafer feed unit for mounting the silicon wafer and holding the wafer so as to be capable of at least one of rotation, movement, and tilting, a grinding unit for grinding the surface of the silicon wafer held by the wafer feed unit, and a laser irradiation repair device for irradiating a laser onto the ground surface of the silicon wafer. The laser irradiation repair device includes a measuring device for measuring the surface condition and / or shape of the silicon wafer held by the wafer feed unit, a laser irradiation unit for irradiating a laser onto the ground surface of the silicon wafer, a displacement mechanism for supporting the laser irradiation unit so as to be capable of at least one of rotation, movement, and tilting displacement relative to the silicon wafer held by the wafer feed unit, and a control device for controlling the laser irradiation conditions and / or irradiation atmosphere based on measurement data by the measuring device.

[0023] Furthermore, in the above, it is preferable that the measuring device is configured to measure the surface state and / or shape of the silicon wafer after grinding and before laser irradiation, during laser irradiation and / or after laser irradiation.

[0024] Furthermore, in the above, it is preferable that a laser is irradiated onto the outer peripheral edge portion and / or the notch portion of the silicon wafer that has been chamfered by the grinding.

[0025] Furthermore, in the above, it is desirable that the measuring device for measuring the surface condition and / or shape of the silicon wafer is composed of any one or a combination of two or more selected from an image measuring means, a capacitance change measuring means, a droplet contact angle measuring means, a Raman spectroscopic measuring means, a surface roughness meter, an acoustic measuring means, an eddy current characteristic measuring means, a reflectance measuring means, an X-ray Lang's method measuring means, an electron beam diffraction measuring means, and a SEM measuring means.

[0026] Furthermore, in the above, it is desirable that the laser irradiation unit has an optical mechanism including at least one of a mirror, a galvanometer mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, and a mask in addition to a laser light source, thereby making it possible to change the laser irradiation conditions.

[0027] Furthermore, in the above, it is preferable that the apparatus further comprises a temperature adjustment device for heating and cooling the silicon wafer held by the wafer transfer unit.

[0028] Furthermore, in the above, it is preferable to further comprise an atmosphere maintaining device for maintaining the gas composition and pressure within a predetermined range in a predetermined processing region surrounding the silicon wafer held by the wafer feed unit.

[0029] Furthermore, in the above, it is desirable that the control device is configured to control at least one of the drive device of the wafer feed unit, the displacement mechanism of the laser irradiation unit, the output characteristics of the laser light source, the operation of the optical mechanism, the operation of the temperature adjustment device, and the operation of the atmosphere maintenance device.

[0030] Furthermore, in the above, since the laser irradiation unit provided in the laser irradiation repair device irradiates multiple locations on the silicon wafer from various directions, it is desirable for the device to have at least one beam splitter that splits the laser from the laser light source into multiple beams.

[0031] Furthermore, in the above, it is desirable to configure the pair of lasers split by the beam splitter to be incident on separate galvanometer mirrors and then reflected, so that the reflected lasers respectively irradiate a pair of outer circumferential arc portions of the notch portion of the silicon wafer and / or irradiate a chamfered slope on the front side and a chamfered slope on the back side of the silicon wafer, respectively.

[0032] Furthermore, in order to achieve the above-mentioned object, a method for grinding and repairing the surface of a silicon wafer according to the present invention is a method for grinding the surface of a silicon wafer and repairing the surface after grinding, comprising the steps of: attaching the silicon wafer to a wafer feed unit that holds the silicon wafer so as to be capable of at least one of rotating, moving, and tilting; grinding the surface of the silicon wafer held by the wafer feed unit with a grinding unit; and irradiating a laser onto the ground surface of the silicon wafer using a laser irradiation repair device. In the use of the laser irradiation repair device, the surface of the silicon wafer held by the wafer feed unit is measured by a measuring device provided in the laser irradiation repair device before laser irradiation. The method includes the steps of: measuring the surface condition and / or shape; setting the laser irradiation conditions and / or irradiation atmosphere based on the measurement data by the measuring device using a control device provided in the laser irradiation repair device; irradiating the ground surface of the silicon wafer with a laser using a laser irradiation unit provided in the laser irradiation repair device in accordance with the conditions set by the control device; measuring the surface condition of the silicon wafer during and / or after laser irradiation using the measuring device to confirm whether the surface of the silicon wafer has been repaired; and terminating the laser irradiation if the surface has been repaired, and resuming or continuing the laser irradiation until the repair is confirmed if the surface has not been repaired.

[0033] Furthermore, in the above, in the step of irradiating a laser onto the ground surface of the silicon wafer by a laser irradiation unit provided in the laser irradiation repair device, it is preferable to irradiate the outer peripheral edge portion and / or notch portion of the silicon wafer that have been chamfered by the grinding with a laser.

[0034] Furthermore, in the above, in the process of irradiating a laser onto the ground surface of the silicon wafer by a laser irradiation unit provided in the laser irradiation repair device, it is desirable to control at least one of the displacement mechanism of the laser irradiation unit, the output characteristics of the laser light source, and the operation of the optical mechanism.

[0035] Furthermore, in the above, in the process of irradiating a laser onto the ground surface of the silicon wafer by a laser irradiation unit provided in the laser irradiation repair device, it is preferable to split the laser from the laser light source of the laser irradiation unit into multiple beams, and to irradiate multiple locations on the silicon wafer from various directions with each of the split laser beams.

[0036] Furthermore, in the above, it is desirable to configure the pair of lasers split by the beam splitter to be incident on separate galvanometer mirrors and then reflected, so that the reflected lasers respectively irradiate a pair of outer circumferential arc portions of the notch portion of the silicon wafer and / or irradiate the chamfered slopes on the front side and the back side of the silicon wafer, respectively.

[0037] Furthermore, in the above, when a laser is irradiated onto the arc portion at the bottom of the recess in the notch portion of the silicon wafer, it is desirable to irradiate the silicon wafer while keeping the laser irradiation direction constant, by placing the center of the radius of curvature of the arc portion at the bottom of the recess in the notch portion on the optical path of the laser L, and rotating the silicon wafer itself around the center of the radius of curvature.

[0038] Furthermore, in the above, when a laser is irradiated onto a straight portion of the recess of the notch portion of the silicon wafer, it is desirable to configure the silicon wafer to move linearly along the direction of the straight portion while maintaining the laser irradiation direction perpendicular to the straight portion. Effect of the Invention

[0039] The present invention is configured as described above, and by measuring the surface condition and shape of the silicon wafer with the measuring device, the scale and state of the damaged area caused by the grinding process can be confirmed and understood, and then the control device controls the laser irradiation conditions and atmosphere via the displacement mechanism, optical mechanism, temperature control device, etc. of the laser irradiation unit to perform effective laser irradiation, thereby making it possible to efficiently repair and flatten the wafer surface. In addition, since a laser scanning method suited to the shape can be executed, appropriate repair can be performed in a short time.

[0040] More specifically, (1) the surface condition after grinding is checked before laser irradiation, and the laser irradiation is performed under appropriate conditions, thereby enabling efficient and effective surface modification; (2) surface treatment using a laser in a short time (10 seconds or less) improves throughput; (3) no abrasive thread, abrasive liquid, chemicals, or cleaning and drying processes are required, making it possible to achieve a process with low environmental impact; (4) since the process is performed in an environment of atmospheric pressure and room temperature, no additional raw materials are required; (5) since laser irradiation is a type of modification by heat treatment and does not involve the removal of material, the original dimensions can be maintained; (6) cracks and distortions can be completely repaired, improving the mechanical strength of the processed product and improving the yield of subsequent processes. [Brief description of the drawings]

[0041] [Figure 1] FIG. 1 is a front view showing a main part of an embodiment of a silicon wafer surface grinding and repairing device according to the present invention. [Diagram 2] FIG. 1 is a plan view showing a main part of an entire device according to an embodiment; [Diagram 3] FIG. 13 is a partially enlarged side view showing a state in which a peripheral precision grinding spindle part is being processed in one embodiment. [Figure 4] A cross-sectional view showing the shape of a silicon wafer after processing using conventional technology. [Diagram 5] FIG. 2 is a cross-sectional view showing the shape of a silicon wafer after processing in one embodiment. [Figure 6]An explanatory diagram showing a notch provided in a silicon wafer and the process of precision grinding and chamfering the notch. [Figure 7] FIG. 1 is a block diagram showing the relationship between the main components of an embodiment of a laser irradiation repair device according to the present invention. [Figure 8] FIG. 1 is a schematic diagram showing examples of measuring devices provided in the laser irradiation repair device of the present invention. [Figure 9] FIG. 1 is an image showing an example of a form in which the laser irradiation repair device of the present invention irradiates a laser in accordance with the shape of a notch portion of a silicon wafer. [Figure 10] 1 is a schematic diagram showing several examples of the manner in which the laser irradiation repair device of the present invention performs laser irradiation in accordance with the shape of the notch portion of a silicon wafer. [Figure 11] FIG. 1 is an image diagram for explaining an example of laser irradiation conditions in the present invention. [Figure 12] Flowchart of the laser irradiation repair method according to the present invention [Figure 13] Enlarged image showing the surface layer of a ground silicon wafer before and after laser irradiation [Figure 14] An explanatory diagram showing the principle of repairing the surface layer of a silicon wafer by laser irradiation [Figure 15] A micrograph of the notch of a silicon wafer after grinding using the grinding and repairing device and method of the present invention and before laser irradiation. [Figure 16] A micrograph of the area of ​​the notch of the silicon wafer shown in FIG. 15 after it has been subjected to laser irradiation treatment using the grinding and repairing device and method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a main part of an apparatus 1 for grinding and repairing a surface of a silicon wafer according to an embodiment of the present invention.

[0043] The grinding and repairing device 1 includes a wafer feed unit 20, a grinding unit 10, and a laser irradiation and repairing device 100. The wafer feed unit 20 mounts a silicon wafer W thereon and holds the silicon wafer W so that it can rotate, move, and tilt. The grinding unit 10 grinds the surface of the silicon wafer W held by the wafer feed unit 20, particularly the outer peripheral edge and notch. The laser irradiation and repairing device 100 irradiates a laser onto the ground surface of the silicon wafer W to flatten the surface roughness and repair the processing-affected layer.

[0044] First, the grinding unit 10 for grinding the silicon wafer W and the wafer feed unit 20 will be described.

[0045] The grinding unit 10 is composed of a grindstone rotation unit 50, a controller that controls the operation of each part of the grinding unit, and the like.

[0046] The drive device 12 of the wafer feed unit 20 includes a wafer supply / storage section, a wafer cleaning / drying section, a wafer transport means, etc., which are not shown, and also has an X-axis base 21 placed on the main body base 11, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23, ..., and an X-table 24 that is moved in the X direction in the figure by an X-axis drive mechanism 25 consisting of a ball screw and a stepping motor.

[0047] The X-table 24 incorporates a Y-table 28 which is moved in the Y direction in the figure by a Y-axis drive mechanism consisting of two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27, . . . and a ball screw and stepping motor (not shown).

[0048] The Y table 28 incorporates a Z table 31 that is guided by two Z-axis guide rails 29, 29 and four Z-axis linear guides (not shown), and is moved in the Z direction in the figure by a Z-axis drive mechanism 30 consisting of a ball screw and a stepping motor.

[0049] A θ-axis motor 32 and a θ-spindle 33 are incorporated in the Z table 31, and a wafer table 34 for suction-mounting a wafer W (a plate-shaped workpiece) is attached to the θ-spindle 33. The wafer table 34 is rotated in the θ direction in the figure around its rotation axis.

[0050] Further, a truing grindstone 41 (hereinafter referred to as a truer 41) used for truing a grindstone for finish-chamfering the peripheral edge of the wafer W is attached concentrically with the wafer table rotation axis below the wafer table .

[0051] By this wafer feed unit 20, the wafer W and the truer 41 are rotated in the θ direction in the figure and moved in the X, Y, and Z directions.

[0052] The outer periphery rough grinding device 60 of the grindstone rotating unit 50 is provided with an outer periphery rough grinding wheel 52 attached thereto, and an outer periphery grindstone spindle 51 that is rotated around its axis by an outer periphery grindstone motor (not shown). The grindstone rotating unit 50 further includes an upper outer periphery fine grinding spindle 54 and an upper outer periphery fine grinding motor 56 attached to a turntable 53 arranged above. Similarly, the turntable 53 is provided with a lower outer periphery fine grinding spindle 57 and a lower outer periphery fine grinding motor (not shown) via a lower fixed frame 59 (partially cut away in FIG. 1). The turntable 53 is further provided with a notch portion rough grinding wheel 61, a notch portion rough grinding spindle 62, a notch portion rough grinding motor 63, a notch portion fine grinding wheel 64, a notch portion fine grinding spindle 65, and a notch portion fine grinding motor 66.

[0053] 2 is a plan view showing the main parts of the entire grinding and repair apparatus 1. The supply and recovery section supplies wafers W to be chamfered from a wafer cassette 70 and recovers the chamfered wafers W into the wafer cassette 70. This operation is performed by the supply and recovery robot 40. The wafer cassette 70 is set on a cassette table 71 and stores a large number of wafers to be chamfered. The supply and recovery robot 40 takes out the wafers W one by one from the wafer cassette 70 and stores the chamfered wafers W into the wafer cassette 70.

[0054] The supply / recovery robot 40 is equipped with a three-axis rotating transfer arm 80, and the transfer arm 80 is equipped with a suction pad (not shown) on its upper surface. The transfer arm 80 holds the wafer W by vacuum-adhering the back surface of the wafer W with the suction pad. That is, the transfer arm 80 of the supply / recovery robot 40 can move back and forth, up and down, and rotate while holding the wafer W, and the transfer of the wafer W is performed by combining these operations.

[0055] The grinding unit 10 is disposed at the front and performs all processes for chamfering the outer periphery of the wafer W, from rough processing to finish processing. The grinding unit 10 is composed of a wafer feed unit 20 and a grindstone rotation unit 50 shown in FIG.

[0056] As shown in Fig. 1, the upper outer periphery precision grinding spindle 54 and the lower outer periphery precision grinding spindle 57 perform finishing processing of the outer periphery chamfer of the wafer W with the rotation axis inclined at 3 to 15°, preferably 6 to 10°, with respect to the rotation axis of the wafer W. As a result, helical grinding is performed, and although weak grinding marks are generated in the diagonal direction on the chamfered portion of the wafer W, the effect of improving the surface roughness of the chamfered portion compared to normal grinding is obtained. However, the grinding method in the grinding unit 10 provided in the grinding and repair device 1 according to the present invention is not limited to such a helical grinding method, and widely includes a normal grinding method along a direction parallel to the main plane of the wafer.

[0057] 3 is an enlarged side view of a portion of the outer periphery precision grinding spindle, and also shows the state during processing. An upper outer periphery precision grinding wheel (upper grinding wheel) 55-1, which is a chamfering wheel for finish-grinding the outer periphery of the wafer W, is attached to the upper outer periphery precision grinding spindle 54, and similarly, a lower outer periphery precision grinding wheel (lower grinding wheel) 55-2 is attached to the lower outer periphery precision grinding spindle 57 such that the rotation axes are approximately concentric with each other with a gap of about 0.1 to 1 mm smaller than the thickness of the wafer W relative to the upper outer periphery precision grinding wheel 55-1.

[0058] The upper outer periphery precision grinding wheel 55-1 and the lower outer periphery precision grinding wheel 55-2 are driven by the upper outer periphery precision grinding spindle 54 and the lower outer periphery precision grinding spindle 57 so that they rotate in opposite directions, that is, in the opposite direction. A grinding groove for processing the wafer W is formed by the upper outer periphery precision grinding wheel 55-1 and the lower outer periphery precision grinding wheel 55-2. A gap is provided at approximately the center of the grinding groove in the rotation axis direction.

[0059] The wafer processing process is carried out in the following order: slice → chamfer → lapping → etching → donor killer → fine chamfer, and various cleaning methods are used between processes to remove dirt. Silicon and other materials are hard and brittle, and if the outer edge of the wafer remains sharp after slicing, it can easily crack or chip during handling in the subsequent processing steps, such as transportation and alignment, and the fragments can scratch or contaminate the wafer surface. To prevent this, in the chamfering process, the outer edge of the cut wafer is chamfered with a diamond-coated chamfering grinding wheel.

[0060] The chamfering process may be performed after the lapping process. This process includes adjusting the outer diameter, which may vary, adjusting the width and length of the orientation flat (OF), and adjusting the dimensions of the tiny notch called the notch.

[0061] 3 also shows the state of the outer periphery precision grinding spindle during processing, and shows the relationship between the rotation direction and force of the upper outer periphery precision grinding spindle 54 and the lower outer periphery precision grinding spindle 57, the inflow and retention of coolant, and the discharge of chips. The upper outer periphery precision grinding spindle 54 rotates left (in the direction indicated by arrow A, i.e., from left to right in the drawing) and is tilted clockwise with respect to the rotation axis of the wafer W, i.e., tilted downward from left to right in the drawing, so that a force is applied to the wafer W as indicated by arrow A. The wafer W is held at its center and its outer periphery is a free end, so that it is bent downward by a component force. On the other hand, the lower outer periphery precision grinding spindle 57 rotates right (in the direction indicated by arrow B, i.e., from right to left in the drawing) and is tilted upward from right to left in the drawing, so that a force is applied to the wafer W as indicated by arrow B.

[0062] The gap between the upper outer periphery precision grinding wheel 55-1 and the lower outer periphery precision grinding wheel 55-2 is symmetrical about the center in the rotation axis direction, so the contact areas between the wafer W and the upper outer periphery precision grinding wheel 55-1 and the lower outer periphery precision grinding wheel 55-2 are equal. Therefore, the grinding resistances are balanced, and no force is generated that bends the wafer W. As a result, the wafer W does not bend from its center to its tip, and the shape accuracy of the machined surface is not affected by bending deformation.

[0063] 3 from the left side of the wafer W toward the center from the outer periphery of the wafer W in the counterclockwise direction, which is the rotation direction of the upper outer periphery precision grinding wheel 55-1. The coolant flows in from the right side of the wafer W toward the center from the outer periphery of the wafer W in the clockwise direction, which is the rotation direction of the lower outer periphery precision grinding wheel 55-2.

[0064] FIG. 4 is a cross-sectional view showing the shape of a wafer W after processing using conventional technology. It shows the shape of the wafer W at the cut position processed with a normal outer periphery precision grinding wheel. The thickness is 740 μm, and A1 on the top surface (front surface) is 340 μm, B1 is 300 μm, and θ1 is 43°, while A2 on the bottom surface (back surface) is 250 μm, B2 is 190 μm, and θ2 is 40°. In other words, the symmetry between the chamfer slope w2 on the front side and the chamfer slope w3 on the back side is lost due to the wafer W being bent downward.

[0065] 5 is a cross-sectional view showing the shape of the wafer W after processing in one embodiment of the present invention, which shows the shape of the wafer W when the outer periphery precision grinding wheel 55 is separated into upper and lower parts as the upper outer periphery precision grinding wheel 55-1 and the lower outer periphery precision grinding wheel 55-2 and rotated in the opposite direction to that of FIG. 4. The thickness is 740 μm, and A1 of the upper surface (front surface) is 290 μm, B1 is 260 μm, and θ1 is 44°, while A2 of the lower surface (back surface) is 290 μm, B2 is 240 μm, and θ2 is 42°, so that the symmetry between the front chamfer slope w2 and the back chamfer slope w3 is improved and the precision is improved.

[0066] In order to facilitate the determination of the crystal orientation and the alignment of the wafer, an orientation flat (abbreviation of orientation flat) or a notch is often formed on the outer periphery of the silicon wafer W. For these wafers, the orientation flat or notch must also be subjected to precision grinding and chamfering.

[0067] An example of a notch and a process for precision grinding chamfering (finish chamfering) are shown in Fig. 6. (d) of Fig. 6 shows a silicon wafer W and a notch wn formed at one location on its outer periphery. The notch wn has a generally V-shaped notch shape, and both ends and the bottom on the outer periphery are arc-shaped.

[0068] 6(a)-(c) show a process of performing the fine chamfering (finish chamfering) of the notch portion wn, but before that, the outer periphery of the silicon wafer W is roughly chamfered by the outer periphery rough grinding grindstone 52. Next, a notch portion wn is formed at one location on the outer periphery of the silicon wafer W using the notch portion rough grinding grindstone 61 shown in FIG. 1. Then, as described above, the outer periphery chamfer of the silicon wafer W is finely ground (finish ground) by the outer periphery fine grinding grindstone 55. Next, the turntable 53 shown in FIG. 1 is rotated, and the notch portion fine grinding grindstone 64 is positioned at the processing position as shown in FIG. 6(a). While rotating the notch portion fine grinding grindstone 64 at high speed in this state, the wafer W is fed in the X and Y directions as shown in FIG. 6(b)-(c), thereby performing fine chamfering along the contour of the notch portion wn. That is, the outer circumferential corner of the notch wn shown in Fig. 6(a) is precision-ground and chamfered in an arc shape with a notch precision grinding wheel 64, and then precision-ground and chamfered through the bottom of the notch wn as shown in Fig. 6(b) to the opposite outer circumferential corner as shown in Fig. 6(c). During this time, the wafer W is not rotated θ, and the notch wn is precision-ground and chamfered by feeding in the X and Y directions.

[0069] With the above, the rough grinding and fine grinding operations of the outer peripheral edge portion and the chamfered slopes on the front and back sides of the notch portion of the silicon wafer W by the grinding unit 10 in the grinding and repair apparatus 1 are completed.

[0070] Next, the configuration and operation of the laser irradiation repair device 100 in the grinding and repairing apparatus 1 according to the present invention will be described with reference to Fig. 1 again. The laser irradiation repairing device 100 irradiates a laser onto the ground portion of the silicon wafer W that has been chamfered and has had its outer peripheral edge portion and / or notch portion ground by the grinding unit 10 as described above, thereby flattening the surface roughness and repairing the processing-affected layer. The laser irradiation repairing device 100 includes a laser irradiation unit 101, a measuring device 102, and a control device 103.

[0071] In the displacement mechanism 120 on which the laser irradiation unit 101 of the laser irradiation repair device 100 is mounted and supported, the components denoted by reference numerals 121 to 133 have the same or similar configurations as the components denoted by reference numerals 21 to 33 in the wafer feed unit 20 of the grinding unit 10, and therefore will not be described here. These components configure the rotary table 135 to be movable in the X-, Y-, and Z-axis directions and rotatable around the axis of the θ spindle 133.

[0072] Furthermore, a tilting stand 136 is attached on the rotating table 135, and the laser irradiation unit 101 is placed thereon. The tilting stand 136 is held by a pivot pin 137 so as to be tiltable with respect to the rotating table 135, and the tilting stand 136 rotates around the pivot pin 137 by rotating a cam 138 rotatably provided by a cam pin 139 using a pulse motor or the like (not shown in the figure). This allows the laser irradiation unit 101 to be tilted up and down, and the direction of laser irradiation toward the silicon wafer W can be continuously adjusted in combination with the movement in the X, Y, and Z axis directions and the rotation about the axis of the θ spindle 133, constituting one of the means for changing the laser irradiation conditions. In the illustrated embodiment, the displacement mechanism 120 is configured to be able to move, rotate, and tilt the laser irradiation unit 101 with respect to the silicon wafer W, but may be configured to be able to perform at least one of the displacement operations of movement, rotation, and tilt depending on the purpose of use.

[0073] The laser irradiation unit 101 is adapted to irradiate a laser onto a predetermined surface of the silicon wafer W after grinding, and in the embodiment shown in FIG. 1, it is adapted to irradiate the chamfered outer peripheral edge portion and / or notch portion of the silicon wafer W with a laser. As shown in the block diagram of FIG. 7, the laser irradiation unit 101 has a laser light source 101a and an optical mechanism 101b, and the optical mechanism 101b is adapted to change the laser irradiation conditions, and in the illustrated embodiment, it includes a relay mirror 101c, a collimator 101d, a mask 101e, a condenser lens 101f, a moving table 101g for adjusting the focal position, and the like. In this case, the laser emitted from the laser light source 101a is redirected by the relay mirror 101c, and is made into a parallel light beam of a predetermined diameter by the collimator 101d, and then travels along the light-shielding mask 101e and is converged by the condenser lens 101f to a predetermined position on the surface of the silicon wafer W to be irradiated. The condenser lens 101f is mounted on a movable table 101g for adjusting the focal position, and the position where the laser is converged is made to coincide with the position to be irradiated on the silicon wafer W. The optical elements constituting the optical mechanism 101b are not limited to those in the illustrated example, but may include at least one of a mirror, a galvanometer mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, a mask, etc., and may be configured to change the laser irradiation conditions by using these. The galvanometer mirror scans the laser on the surface to be irradiated by rotating or vibrating it.

[0074] The laser irradiation repair apparatus 100 further includes a measuring device 102 and a control device 103. Although not shown in Fig. 1, if necessary, as shown in Fig. 7, it may also include a temperature control device 104 for heating and cooling the silicon wafer W held by the wafer feed unit 20, and an atmosphere maintaining device 105 for maintaining the gas composition and pressure in a predetermined processing area surrounding the silicon wafer W within a predetermined range.

[0075] 1, the measuring device 102 has a measuring device main body 102a that is held in the vicinity of a location on the silicon wafer W to be irradiated with the laser via a support 102b attached to the Z table 31 of the wafer feed unit 20 in a non-contact state with the silicon wafer W. The measuring device main body 102a is configured so that its position can be adjusted on the support 102b, and preferably the support 102b is also configured so that it can move appropriately, so that the surface state (surface roughness, reflection characteristics, scattered light, etc.) and / or shape of a desired location on the silicon wafer W can be measured.

[0076] In measuring the surface condition of the silicon wafer W, first, in order to set the irradiation conditions and irradiation atmosphere at the start of the laser irradiation, the surface condition of the silicon wafer W before the laser irradiation is measured after grinding of the silicon wafer W is completed. It is also desirable to configure the measurement to be performed during the laser irradiation to prevent excessive exposure to the laser and to monitor the suitability of the irradiation conditions, and further to be performed after the irradiation to determine the suitability of the irradiation results.

[0077] Measurement of the surface state and / or shape of the silicon wafer W by the measuring device 102 is desirably non-destructive, and specific measuring means may be, for example, any one selected from image measuring means, capacitance change measuring means, droplet contact angle measuring means, Raman spectroscopy measuring means, surface roughness meter, acoustic measuring means, eddy current characteristic measuring means, reflectance measuring means, X-ray Lang's method measuring means, electron beam diffraction measuring means, SEM measuring means, etc., or a combination of two or more of them is also recommended. Several examples of these will be described with reference to FIG.

[0078] 8(a) shows an image measuring means, which irradiates the chamfered slope w2 with laser light or light of a desired wavelength range from a measurement light source 140 to measure the surface roughness of the chamfered slope w2 on the front side of the silicon wafer W, captures the image with a detector 141 such as a hyperspectral camera, detects the surface roughness by image analysis, and selects and controls the irradiation conditions from the laser irradiation unit 101 based on the detection result to flatten the chamfered slope w2 and repair the processing-affected layer. Machine learning means based on trial experiments and comparison with a control sample may be used to determine the surface roughness by such image analysis.

[0079] 8(b) shows a measurement device using a capacitance change measurement means. In this case, an electrode 142 is placed close to the outer peripheral end face w1 and the chamfered slopes w2 and w3 on the front and back sides of the silicon wafer W, and a voltage is applied between the silicon wafer W and the electrode 142 from a DC power source 143. By detecting the electrostatic attractive force F, the surface roughness, etc. of the outer peripheral end face w1 and the chamfered slopes w2 and w3 on the front and back sides are detected.

[0080] 8(c) shows a measurement device using a droplet contact angle measuring means. In this case, an appropriate droplet 144 is attached to the chamfered slope w2 on the front side of the silicon wafer W, for example, and the contact angle 144a of the droplet 144 with the chamfered slope w2 is measured. This utilizes the fact that the wettability of the chamfered slope w2 changes depending on the level of surface roughness, and the contact angle 144a of the droplet 144 also changes accordingly.

[0081] As the measuring means, for example, a Raman spectroscopic measuring means (not shown) can be used. In this case, by measuring the distortion from the Raman shift, the change in the crystal state inside the silicon wafer W can be detected, and the level of the alteration caused by the grinding process can be determined based on the result, and the laser irradiation conditions, etc. can be optimally controlled based on the result. In addition, it is possible to detect using ultrasonic waves or AE waves that do not involve destruction by an acoustic measuring means, or to use a non-contact or contact type surface roughness meter, and it is also possible to measure the conductivity of the chamfered slope, etc., by an eddy current characteristic measuring means, and to determine the level of the alteration caused by the grinding process. Furthermore, it is possible to determine the scale and state of the alteration of the surface of the silicon wafer W caused by the grinding process by using various known means such as a reflectance measuring means, an X-ray Lang method measuring means, an electron beam diffraction measuring means, an SEM measuring means, etc., and to optimally and efficiently adjust and control the laser irradiation conditions, etc. based on the result.

[0082] Next, the control device 103 of the laser irradiation repair device 100 has a function of controlling the laser irradiation conditions and / or irradiation atmosphere based on the measurement data by the measuring device 102. In the embodiment shown in Fig. 1, the control device 103 is provided inside the base body of the grinding wheel rotation unit 50, but the location where it is installed is free, and it may be configured as a part of the control device for the entire grinding repair device 1.

[0083] As shown in the block diagram of FIG. 7, the control objects of the control device 103 of the laser irradiation repair device 100 in the illustrated embodiment are the driving device 12 of the wafer feed unit 20, the displacement mechanism 120 of the laser irradiation unit, the output characteristics (energy density, etc.) of the laser light source 101a, the operation of the optical mechanism 101b (adjustment of the laser direction, light beam diameter, focal position, scanning range and frequency, etc.), the operation of the temperature adjustment device 104, the operation of the atmosphere maintenance device 105, etc., and these control objects are controlled according to a predetermined program based on the measurement data of the measurement device 102.

[0084] As the temperature control device 104, as described above, a device for heating and cooling the silicon wafer W to eliminate the effects of thermal stress, a device for promoting and optimizing the laser irradiation effect, a device for keeping the temperatures of the wafer feed unit 20 and the laser irradiation unit 101 constant in order to eliminate the effects of thermal stress on these units, etc. may be provided.

[0085] Also provided is an atmosphere maintaining device 105 for maintaining the gas composition and pressure in a predetermined processing region surrounding the silicon wafer W within a predetermined range, thereby forming and maintaining an atmosphere with gas components, pressure, etc. suitable for the processing conditions.

[0086] In addition, a shield mechanism is provided to prevent leakage of the laser from the processing region, and such a shield mechanism is also subject to control by the control device 103 as necessary.

[0087] Next, an example of an irradiation form that can effectively and efficiently repair the surface condition and shape of the silicon wafer after grinding by the above-mentioned laser irradiation repair device 100 will be described. In this case, the irradiation conditions are generally changed according to the surface condition by changing the laser output characteristics, energy density, etc., using the laser light source 101a and the optical mechanism 101b. Moreover, the irradiation is generally changed according to the shape of the irradiation area by changing the position and attitude of the laser irradiation unit and / or the silicon wafer (workpiece), and by changing the attitude of the silicon wafer side or the direction of the mirror in the optical mechanism with respect to the depth direction of the notch. However, the present invention is not limited to these, and it is also possible to appropriately select or combine these various means according to the situation.

[0088] Fig. 9 shows an example of an irradiation form according to the present invention that matches the shape of the chamfered notch of the silicon wafer W. More specifically, Fig. 9(a) shows an optical function configured to simultaneously and in parallel irradiate two locations, the outer circumferential arc portions w4 and w5 of the chamfered notch wn, and also continuously irradiate the front chamfered slope w2, the back chamfered slope w3, and the end face w1 of the notch recess, as shown in Fig. 9(b) [an enlarged cross-sectional view along BB in Fig. 9(a)]. Note that, for the sake of convenience, Fig. 9(a) shows an enlarged view of only the notch wn of the silicon wafer W.

[0089] Specifically, a pair of lasers L11a and L12a split by a beam splitter 101m are incident on individual galvanometer mirrors 101n and 101o, and are further reflected, so that the pair of outer circumferential arc portions w4 and w5 of the notch portion wn are irradiated by the respective reflected lasers L11b and L12b. At this time, by rotating or reciprocating the galvanometer mirrors 101n and 101o, the direction of the reflected lasers L11b and L12b is changed, and the chamfered slope w2 on the front side of the outer circumferential arc portions w4 and w5, the chamfered slope w3 on the back side, and the outer circumferential end surface w1 are efficiently irradiated with the laser in parallel in a scanning manner (FIG. 9(b)). In the illustrated embodiment, the galvanometer mirrors 101n and 101o are parabolic mirrors, and are focused on the outer circumferential arc portions w4 and w5, which are the irradiation targets. This focal position can be adjusted by adjusting the moving table 101g of the condenser lens 101f shown in Fig. 7, for example, of the laser beam before it enters the beam splitter 101m. In Fig. 9(a), O1 is the center of the radius of curvature of the arc portion w6 at the bottom of the recess of the notch portion wn, and O2 and O3 are the centers of the radius of curvature of the arc portions w4 and w5 of the notch portion wn. Note that the uneven shapes drawn on the front chamfered slope w2 and the back chamfered slope w3 in Fig. 9(b) are enlarged images of the surface roughness caused by grinding.

[0090] By using such an optical mechanism, if the focal points of the galvanometer mirrors 101n and 101o are aligned with the peripheral chamfered slopes of the rotating silicon wafer W and laser irradiation is performed, not only the notch portion but also the front and back chamfered slopes and end faces of the outer periphery of the silicon wafer W can be repaired efficiently and effectively, for example, in less than 10 seconds for the entire periphery. As shown in Fig. 9(a), a polarizer 101l and a beam splitter 101k for adjusting the light beam are provided in front of the beam splitter 101m in Fig. 9(a), and the front of that is connected to the optical mechanism 101b shown in Fig. 7, and the optical elements shown in Fig. 9(a) are also included in the optical mechanism 101b, and the entirety of them constitute the optical mechanism of the present invention.

[0091] Further, Fig. 10(a) shows another configuration example in which the chamfered slope w2 on the front side, the chamfered slope w3 on the back side, and the peripheral edge w1 of the silicon wafer W are simultaneously irradiated. That is, a pair of lasers L13a and L14a split by a beam splitter 101h are made to enter individual galvanometer mirrors 101i and 101j, respectively, and are further reflected, and the reflected lasers L13b and L14b respectively irradiate the chamfered slope w2 on the front side and the chamfered slope w3 on the back side of the silicon wafer W. More specifically, in this irradiation example, the laser emitted from the laser light source 101a shown in Fig. 7 passes through a predetermined optical element in the optical mechanism 101b, and then passes through the beam splitter 101h in Fig. 10(a) to be split into two lasers L13a and L14a. Among these, the laser L13a is reflected by a galvanometer mirror 101i placed on the optical path and irradiated onto the chamfered slope w2 on the front side of the silicon wafer W. By rotating or pivoting the galvanometer mirror 101i within a predetermined angle range, the reflected laser L13b irradiates the slope w2 in a scanning manner. Similarly, the laser L14a is reflected by a galvanometer mirror 101j placed on the optical path and irradiates onto the chamfered slope w3 on the back side of the silicon wafer W in a scanning manner. In order to irradiate the peripheral edge w1 of the silicon wafer W at this time, the arrangement of each optical element may be adjusted so that the edge w1 is included within the scanning range of the galvanometer mirrors 101i and / or 101j. Alternatively, the orientation of the silicon wafer W may be changed during the irradiation period so that the entire irradiation target area is irradiated. In the example shown in FIG. 10(a), the peripheral edge w1 of the silicon wafer W is irradiated by the transmitted laser L15 of the beam splitter 101h. In this embodiment, the beam splitter 101h and the galvanometer mirrors 101i and 101j are also included as components of the optical mechanism 101b.

[0092] Next, FIG. 10(b) shows a preferred irradiation form when the laser L is irradiated to the arc portion w6 of the bottom of the recess of the notch portion wn of the silicon wafer W. In this case, the center O1 of the radius of curvature of the arc portion w6 of the bottom of the recess of the notch portion wn is placed on the optical path of the laser L (in other words, the laser L is set to pass through the center O1), and the silicon wafer W itself is irradiated while rotating around this O1. Alternatively, the laser irradiation direction may be rotated around O1 while the center O1 is placed on the optical path of the laser L. This allows the laser L to continue to be irradiated in a state where it is approximately perpendicular to the curved surface of the arc portion w6, resulting in an effective and efficient irradiation effect. To rotate the silicon wafer W about the center O1 as described above, for example, the center O1 of the radius of curvature of the arc portion w6 at the bottom of the recess of the notch is positioned at the rotation center of the wafer table 34 of the wafer feed unit 20 of the grinding and repair apparatus 1 shown in FIG. 1, and the wafer table 34 is then rotated.

[0093] Next, FIG. 10(c) shows a preferred irradiation form when the laser L is irradiated to the straight line portion w7 (similarly for w8) of the recess of the notch portion wn of the silicon wafer W. In this case, the silicon wafer W is moved linearly along the direction of the straight line portion w7 while the irradiation direction of the laser L is kept perpendicular to the straight line portion w7. This allows the laser L to continue to be irradiated perpendicular to the plane of the straight line portion w7, and an effective and efficient irradiation effect can be obtained. To move the silicon wafer W linearly along the direction of the straight line portion w7, for example, the X table 24 and the Y table 28 of the wafer feed unit 20 of the grinding and repairing device 1 shown in FIG. 1 can be used to move the silicon wafer W linearly along the direction of the straight line portion w7.

[0094] Fig. 11(a) shows an enlarged cross-sectional view of the chamfered portion on the outer periphery of a silicon wafer W to be irradiated with a laser according to the present invention, and Fig. 11(b) shows a plan view of the notch portion. An example of the specifications of suitable irradiation conditions for such an irradiation target is laser wavelength λ = 532 nm, pulse width = 3 to 7 ns (generally 10 ns or less. However, if the damage to the surface of the silicon wafer is significant and deep, up to about 50 ns may be necessary), energy per pulse = 60 to 80 μJ, and energy density = 0.6 to 0.8 J / cm 2 (Generally, 0.24 to 1.44 J / cm 2 (range), irradiation area = 0.5 mm × 0.5 mm, ambient pressure = atmospheric pressure.

[0095] Next, a method for repairing the surface of a silicon wafer by grinding according to the present invention will be described with reference to Fig. 12. More specifically, the method according to the present invention is a method for grinding the surface of a silicon wafer W and repairing the surface after grinding.

[0096] As shown in FIG. 12, the method according to the present invention first performs the step of (1) mounting a silicon wafer W on a wafer feed unit 20 that holds the silicon wafer W so as to enable at least one of rotation, movement, and tilting.

[0097] Next, (2) a step of grinding the surface of the silicon wafer W held by the wafer feed unit 20 by the grinding unit 10 is carried out.

[0098] Next, (3) before laser irradiation by the laser irradiation repair apparatus 100, a step of measuring the surface condition and / or shape of the silicon wafer W held by the wafer feed unit 20 is performed by a measuring device 102 provided in the laser irradiation repair apparatus.

[0099] Next, (4) a step of setting the laser irradiation conditions and / or irradiation atmosphere based on the measurement data by the measuring device 102 is executed by the control device 103 provided in the laser irradiation repair device 100 .

[0100] Next, (5) a step of irradiating the ground surface of the silicon wafer W with a laser by the laser irradiation unit 101 provided in the laser irradiation repair apparatus 100 according to the conditions set by the control device 103 is executed.

[0101] Next, (6) a step of measuring the surface state of the silicon wafer by the measuring device 102 during and / or after the laser irradiation and confirming whether the surface of the silicon wafer has been repaired is executed.

[0102] Next, (7) a step of terminating the laser irradiation if the defect is repaired, and resuming or continuing the laser irradiation until the defect is repaired if the defect is not repaired, is executed.

[0103] As described above, according to the method of the present invention, laser irradiation can be efficiently performed according to the surface condition and shape of the silicon wafer W, so that in the process of irradiating a laser onto the ground surface of the silicon wafer W by the laser irradiation unit 101 provided in the laser irradiation repair apparatus 100, the operation of irradiating a laser onto the outer peripheral edge portion and / or notch portion chamfered by the grinding of the silicon wafer W can be suitably performed.

[0104] Furthermore, when the method of the present invention is used, in the step of irradiating the laser, as described above, at least one of the displacement mechanism 120 of the laser irradiation unit, the output characteristics (energy density, etc.) of the laser light source 101a, and the operation of the optical mechanism 101b (laser direction, light beam diameter, scanning range and frequency, etc.) is controlled.

[0105] Furthermore, according to the method of the present invention, a laser is irradiated in accordance with the shape of the irradiated portion of the silicon wafer W obtained by the measuring device 102. As described above, the laser from the laser light source 101a of the laser irradiation unit 101 is split into multiple beams, and each of the split laser beams is used to irradiate multiple locations on the silicon wafer W from various directions, making it possible to efficiently perform irradiation operations on the outer periphery and notch portions which have different shapes.

[0106] Furthermore, when the method of the present invention is used, as explained with reference to FIG. 9, a pair of lasers L11a and L12a separated by beam splitter 101m can be made to enter individual galvanometer mirrors 101n and 101o, respectively, and then reflected, so that a pair of outer peripheral arc portions w4 and w5 of the notch portion wn of the silicon wafer can be simultaneously irradiated with the respective reflected lasers L11b and L12b. This makes it possible to efficiently irradiate the notch portion, which was previously difficult to irradiate efficiently and satisfactorily.

[0107] Furthermore, when the method of the present invention is used, as explained with reference to FIG. 10(a), a pair of lasers L13a and L14a separated by a beam splitter 101h can be made to enter individual galvanometer mirrors 101i and 101j, respectively, and then reflected, so that the reflected lasers L13b and L14b can be used to simultaneously irradiate the chamfered slope w2 on the front side and the chamfered slope w3 on the back side of the silicon wafer, respectively. This makes it possible to efficiently irradiate the chamfered slopes on both the front and back sides, which was previously difficult to irradiate efficiently and satisfactorily.

[0108] Furthermore, according to the method of the present invention, as explained with reference to FIG. 10(b), in the case where a laser beam L is irradiated onto the arc portion w6 at the bottom of the recess of the notch portion wn of the silicon wafer W, the center O1 of the radius of curvature of the arc portion w6 at the bottom of the recess of the notch portion wn is placed on the optical path of the laser L while keeping the irradiation direction of the laser L constant, and the silicon wafer W itself can be irradiated while rotating around this O1. This makes it possible to efficiently perform the irradiation operation on the arc portion at the bottom of the recess of the notch portion wn, which was previously difficult to irradiate efficiently and satisfactorily.

[0109] Furthermore, according to the method of the present invention, as explained with reference to FIG. 10(c), in the case where a laser L is irradiated onto the straight line portion w7 (w8) of the recess of the notch portion wn of the silicon wafer W, it is possible to move the silicon wafer W linearly along the direction of the straight line portion w7 (w8) while maintaining the irradiation direction of the laser L perpendicular to the straight line portion w7 (w8). This makes it possible to efficiently perform the irradiation operation onto the straight line portion of the recess of the notch portion wn, which was previously difficult to irradiate efficiently and satisfactorily.

[0110] In order to explain the repair effect of the present invention by irradiating a laser on the silicon wafer surface, Fig. 13 shows an image of the case where the unevenness of the surface layer generated when the surface of the silicon wafer W is ground is flattened and repaired by irradiating a laser. That is, as shown in Fig. 13(a), when the surface of the silicon wafer W is ground, the surface region of the original single crystal layer w9 becomes a process-affected layer and becomes a rough surface having unevenness w10. When the rough surface is irradiated with a laser L, the irradiated surface region melts and becomes a flat surface w11 due to surface tension as shown in Fig. 13(b), and the surface vicinity region is single-crystallized again and repaired. The principle will be explained with reference to Fig. 14.

[0111] As shown in Fig. 14(a), the ground portion of the silicon wafer has crystal defects in the layer near the surface of the processed portion due to mechanical processing, resulting in a process-affected layer such as an amorphous layer or a dislocation layer. Since the laser absorption rate of this process-affected layer is significantly higher than that of the single crystal region, the process-affected layer melts when irradiated with a laser (nanosecond pulse laser) as shown in (b), and the melted region expands due to thermal conduction as shown in (c), while the surface of the melted region is flattened by surface tension. When the laser irradiation is stopped, as shown in (d), epitaxial crystals in the liquid phase grow using the single crystal region as a seed, which eliminates the crystal lattice defects that occurred during the grinding process, and the laser-irradiated portion is restored to the original single crystal as shown in (e) (see Patent Document 4).

[0112] Finally, the effect of the present invention will be explained by comparing the surface conditions before and after irradiating a laser on the surface of a silicon wafer after grinding by the grinding repair device and method of the present invention with reference to Figures 15 and 16. Figure 15 is a microscope photograph of the notch part of a silicon wafer before laser irradiation in a state where grinding has been completed by the grinding repair device and method of the present invention, and Figure 16 is a microscope photograph of the post-grinding area of ​​the notch part of the silicon wafer shown in Figure 15 after laser irradiation processing by the grinding repair device and method of the present invention.

[0113] As shown in FIG. 15, after the grinding process, the ground surface including the chamfered slope w2 of the notch portion wn of the silicon wafer W before the laser irradiation has fine grinding marks (scratches or streaks). That is, the grinding marks consisting of many fine, approximately parallel uneven streaks are formed in the entire area from the outer circumferential arc portion w4 of the notch portion wn to the other outer circumferential arc portion w5 through the straight portion w7, the concave bottom arc portion w6, and the other straight portion w8, resulting in a rough surface. Such grinding marks are formed not only in the notch portion wn shown in the photograph, but also in the peripheral end face and the outer circumferential chamfered slope of the silicon wafer W. The damage caused by the grinding process is not limited to the surface that can be observed with a microscope as described above, but extends to the inside as a process-affected layer in which a region at a certain depth from the surface has changed into an amorphous layer or a dislocation layer, as described above.

[0114] Fig. 16 shows the state after the surface region of the notch part of the silicon wafer shown in Fig. 15 has been subjected to a laser irradiation process by the grinding and repairing device and method according to the present invention. That is, after the laser irradiation process, as described above, it can be visually confirmed that the surface of the region from one outer circumferential arc part w4 of the notch part wn through the straight part w7, the concave bottom arc part w6, the other straight part w8, and the other outer circumferential arc part w5 is a smooth, glossy, flat surface as a whole. That is, by irradiating the ground surface with a laser from various directions under irradiation conditions such as appropriate intensity while making the laser correspond to the shape and surface condition of the notch part wn, the notch part wn, which is usually difficult to irradiate uniformly and well, can be irradiated with an appropriate laser evenly, efficiently, quickly, and effectively according to the present invention, and the damage caused by the grinding process can be repaired based on the above-mentioned repair principle. [Industrial Applicability]

[0115] The present invention has the above-mentioned configuration, and by using the measuring device to measure the surface condition and shape of the silicon wafer, the scale and state of the damaged area caused by the grinding process can be confirmed and understood, and then the control device controls the laser irradiation conditions and atmosphere via the displacement mechanism, optical mechanism, temperature control device, etc. of the laser irradiation unit to perform effective laser irradiation, thereby making it possible to efficiently repair and flatten the wafer surface. In addition, since a laser scanning method suited to the shape can be executed, appropriate repair can be performed in a short time. [Explanation of symbols]

[0116] L…Laser W…Silicon wafer (workpiece) w1: Outer periphery or end face of notch recess w2: chamfered bevel on the front side w3…Beveled back surface w4, w5...Circular arc portion on the outer periphery of the notch w6: Arc part of the bottom of the notch w7, w8...Straight line part of the notch recess w9…single crystal layer w10…Unevenness w11…Flat surface wn…Notch O1: Center of the radius of curvature of the arc part of the bottom of the notch O2, O3: Center of the curvature radius of the outer circumferential arc of the notch 1... Grinding and repair device according to the present invention 10…Grinding unit 11...Main body base 12...Drive device for wafer feed unit 20...Wafer transfer unit 21, 121…X-axis base 22, 122…X-axis guide rail 23, 123…X-axis linear guide 24, 124…X table 25, 125…X-axis drive mechanism 26, 126…Y-axis guide rail 27, 127…Y-axis linear guide 28, 128…Y table 29, 129…Z-axis guide rail 30, 130...Z-axis drive mechanism 31, 131...Z table 32, 132...θ-axis motor 33, 133…θ spindle 34, 134...Wafer table 40…Supply and collection robot 41...True 50…Grinding wheel rotation unit 51...Periphery grinding wheel spindle 52...Outer circumference rough grinding wheel 53…Turntable 54...Upper outer periphery precision grinding spindle 55...Periphery precision grinding wheel 55-1...Upper outer circumference precision grinding wheel (Upper grinding wheel) 55-2...Lower outer circumference precision grinding wheel (lower grinding wheel) 56...Upper outer circumference precision grinding motor 57...Lower peripheral precision grinding spindle 59…Lower fixed frame 60...Outer circumference rough grinding device 61...Notch rough grinding wheel 62...Notch rough grinding spindle 63...Notch rough grinding motor 64...Notch precision grinding wheel 65...Notch precision grinding spindle 66...Notch precision grinding motor 70...Wafer cassette 71…Cassette table 80...Transport arm 100...Laser irradiation repair device 101...Laser irradiation unit 101a...Laser light source 101b…Optical mechanism 101c…Relay mirror 101d…Collimator 101e…Mask 101f…Condenser lens 101g...Moving table for adjusting the focal position 101h…Beam splitter 101i, 101j...Galvanometer mirror 101k…Beam splitter 101l…Polarizer 101m…Beam splitter 101n, 101o...Galvano mirror 102...Measuring equipment 102a…Measuring instrument body 102b…post 103...Control device 104...Temperature control device 105...Atmosphere maintenance device 120...Displacement mechanism 135…Rotary table 136...Tilting stand 137…Pivot pin 138…Cam 139…Camping 140…Measurement light source 141…Detector 142...Electrode 143…DC power supply 144...droplet 144a…Contact angle

Claims

1. a grinding unit for grinding a surface of a silicon wafer; a laser irradiation repair device that irradiates a laser onto the ground surface of the silicon wafer in order to repair the surface of the silicon wafer; The laser irradiation repair device controls the laser irradiation conditions and / or irradiation atmosphere based on measurement data obtained by measuring the surface state and / or shape of the silicon wafer, and uses a displacement mechanism to adjust the irradiation position of the laser on the silicon wafer, thereby controlling the displacement mechanism based on the center of curvature radius of the bottom of the recess in the notch portion of the silicon wafer, thereby irradiating the notch portion with a laser.

2. 2. The silicon wafer surface grinding repair device according to claim 1, wherein the measurement data is measured by one or a combination of two or more selected from the group consisting of an image measurement means, a capacitance change measurement means, a droplet contact angle measurement means, a Raman spectroscopy measurement means, a surface roughness meter, an acoustic measurement means, an eddy current characteristic measurement means, a reflectance measurement means, an X-ray Lang's method measurement means, an electron beam diffraction measurement means, and a SEM measurement means.

3. The laser irradiation repair device is a grinding repair device for a silicon wafer surface as described in claim 1 or 2, characterized in that in addition to a laser light source, it has an optical mechanism including at least one of a mirror, a galvanometer mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, and a mask, and the laser irradiation conditions can be changed by the optical mechanism.

4. A grinding and repairing method applied to a grinding and repairing device for a surface of a silicon wafer, the grinding and repairing device including a grinding unit that grinds a surface of a silicon wafer, and a laser irradiation and repairing device that irradiates a laser onto the ground surface of the silicon wafer in order to repair the surface of the silicon wafer, the method comprising: controlling the laser irradiation conditions and / or irradiation atmosphere based on measurement data obtained by measuring the surface state and / or shape of the silicon wafer; a step of adjusting an irradiation position of the laser with respect to the silicon wafer based on a center of a radius of curvature of a bottom of a recess in a notch portion of the silicon wafer, and irradiating the notch portion with a laser.

Images