JP2020141088A - Grinding repair device and grinding repair method for surface of silicon wafer - Google Patents

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

The present invention grinds the surface of various materials such as silicon, sapphire, zirconia, and glass, particularly plate-shaped workpieces such as semiconductor wafers and glass panels (these are referred to as "silicon wafers" in the present application), and at the same time. Regarding the device that repairs and flattens the roughness due to the grinding marks on the surface after grinding and repairs the work-altered layer (returning to a single crystal, etc.), the repair operation can be performed efficiently by laser irradiation. Regarding the device. In particular, the surface of the silicon wafer after grinding of the outer peripheral edge and notch is irradiated with a laser to improve the surface such as repair of roughness and repair of the work-altered layer, resulting in damage such as crack growth in the subsequent process. Provide a technique suitable for suppressing.

In recent years, there has been a strong demand for improving the quality of wafers, and the processing state of wafer end faces (edges) and notches has been emphasized. Semiconductor wafers such as silicon wafers used for manufacturing semiconductor devices prevent chipping due to handling. Therefore, chamfering is performed by grinding the edge portion and the like, and mirror chamfering is performed by polishing. That is, in the semiconductor manufacturing process, quality improvement of edge characteristics is an indispensable process from wafer manufacturing to device manufacturing.

Silicon etc. is hard and brittle, and if the edge of the wafer remains sharp during slicing, it will easily crack or chip during handling such as transportation and alignment in the subsequent processing process, and the fragments may damage the wafer surface. It gets polluted. To prevent this, the edges and notches of the cut wafer are chamfered with a diamond-coated chamfering grindstone.

In addition, masking printing, sensor electrodes are formed on a thin and lightweight glass substrate for smartphones and tablets, and then cutting is performed. At that time, chamfering processing quality, processed surface roughness, etc. The generation of microcracks directly affects the end face strength of the glass substrate.

The following Patent Documents 1, 2 and 3 disclose improved techniques for chamfering such wafers. That is, Patent Document 1 discloses a wafer edge processing apparatus or the like capable of processing the outer peripheral edge of a silicon wafer or the like with high accuracy by using a polishing tape. Further, Patent Document 2 discloses a chamfering apparatus capable of improving processing accuracy by eliminating bending deformation of the wafer that occurs when the outer peripheral edge of the wafer is helically ground. Further, Patent Document 3 discloses a chamfering method capable of obtaining good processed surface roughness in chamfering a notch portion of a notched wafer.

After grinding the outer peripheral edge of the silicon wafer as described above or after grinding the notch, the surface is buffed in order to remove and smooth the grinding marks on the surface. However, the surface after grinding has been performed. Has cracks and processing strains, or cannot completely remove the amorphous surface part, so in the subsequent process, the yield will deteriorate due to damage caused by cracks and the like extending from such parts of the wafer. .. In addition, the polishing pressure (load) during buffing may increase processing strain and crystal transition.

Further, since buffing is a polishing process (removal process) by removing a material, when the dimensions immediately after grinding and the dimensions after buffing are compared, the dimensions after buffing change to some extent. In addition, buffing requires consumables such as polishing threads, polishing liquids, and chemicals, and processes such as cleaning (removal of foreign substances) and drying after polishing, which is costly.

Unlike the mechanical surface repair processing as described above, Patent Document 4 discloses a method of repairing surface defects by irradiating a processing alteration layer on the surface generated by grinding a single crystal wafer with a laser. Has been done. However, the existing surface modification by laser irradiation is for a simple flat surface, and irradiation is performed under conditions according to a complicated shape and various surface conditions after grinding, and irradiation is performed while monitoring the irradiation result. Since it is not a thing, high-speed and effective processing was difficult.

Japanese Patent No. 5700264 JP-A-2017-159421 Japanese Unexamined Patent Publication No. 2005-153129 Japanese Unexamined Patent Publication No. 2008-147639

As described above, when the conventional means for repairing the surface state of a silicon wafer after grinding is used, in the case of buffing, surface defects cannot be completely repaired or the original dimensions cannot be strictly maintained, resulting in a yield. There are problems such as poor (particularly notch portion), high cost, and in the case of laser irradiation, quick and effective repair results cannot be obtained according to the surface condition and shape after grinding.

In view of these problems, an object of the present invention is to grind a work material (referred to as "silicon wafer" in the present application) and to provide a pulse with a pulse width of nanoseconds in the grinding end region. An object of the present invention is to provide an apparatus and a method for repairing processing damage by irradiating a laser (referred to as “laser” in the present application).

More specifically, an object of the present invention is to provide a technique for repairing (single crystallizing, etc.) and improving roughness (flattening) of a work-altered layer at an outer peripheral edge portion and / or notch portion of a silicon wafer. To do.

Another object of the present invention is to provide a method and an apparatus for diagnosing the scale and situation of a damaged portion and performing effective irradiation.

Furthermore, another object of the present invention is to provide an efficient laser irradiation method and apparatus suitable for the shapes of edge portions and notch portions having different shapes.

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

Therefore, an object of the present invention is to confirm the surface condition and shape of the silicon wafer to be repaired before, during, and / or after laser irradiation, and to respond to the situation such as distortion and breakage. By irradiating the laser under the conditions, it is possible to efficiently and effectively modify the surface.

Another object of the present invention is to completely repair cracks and strains, improve the mechanical strength of the object to be repaired, and improve the yield in the post-process.

Another object of the present invention is to achieve a process having a small environmental load by eliminating the need for consumables such as polishing threads, polishing liquids, and chemicals, and cleaning and drying steps.

Further, an object of the present invention is to enable a simple process that can be performed in an environment such as atmospheric pressure and normal temperature and does not require other additional raw materials.

Another object of the present invention is to enable restoration in which the original dimensions (accuracy) are maintained by performing modification by heat treatment without removing the material (processed material) to be restored. ..

In order to achieve the above object, the silicon wafer surface grinding / repairing device according to the present invention is a silicon wafer surface grinding / repairing device, and at least one of mounting, rotating, moving, and tilting the silicon wafer. A wafer feed unit that holds the wafer so that it can be fed, a grinding unit that grinds the surface of the silicon wafer held by the wafer feed unit, and a laser irradiation repair device that irradiates the surface of the ground silicon wafer with a laser. The laser irradiation repair device includes a measuring device for measuring the surface condition and / or shape of a silicon wafer held in the wafer feed unit, and a laser irradiation unit for irradiating the ground surface of the silicon wafer with a laser. A displacement mechanism that supports the laser irradiation unit so that at least one of rotation, movement, and tilt can be displaced with respect to the silicon wafer held by the wafer feed unit, and the measuring device. It is characterized by having a control device for controlling the irradiation conditions and / or the irradiation atmosphere of the laser based on the measurement data obtained by the silicon wafer.

Further, in the above, it is desirable 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 irradiation.

Further, in the above, it is desirable that the outer peripheral edge portion and / or the notch portion chamfered by the grinding of the silicon wafer is irradiated with a laser.

Further, in the above, the measuring device for measuring the surface state and / or shape of the silicon wafer is an image measuring means, a capacitance change measuring means, a droplet contact angle measuring means, a Raman spectroscopic measuring means, and a surface roughness meter. , Acoustic measuring means, eddy current characteristic measuring means, reflectance measuring means, X-ray rung method measuring means, electron beam diffraction measuring means, SEM measuring means, any one or a combination of two or more. It is desirable to be configured.

Further, in the above, 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. It is desirable to configure the laser irradiation conditions so that they can be changed.

Further, in the above, it is desirable to further include a temperature control device for heating and cooling the silicon wafer held in the wafer feed unit.

Further, in the above, it is further desirable to further include an atmosphere maintaining device for maintaining the gas composition and pressure of a predetermined processing region surrounding the silicon wafer held in the wafer feed unit within a predetermined range.

Further, in the above, the control device is a driving device of the wafer feeding unit, a displacement mechanism of the laser irradiation unit, an output characteristic of the laser light source, an operation of the optical mechanism, an operation of the temperature control device, and the atmosphere maintenance device. It is desirable to be configured to control at least one of the operations of.

Further, in the above, since the laser irradiation unit provided in the laser irradiation repair device irradiates a plurality of locations on the silicon wafer from various directions, it has at least one beam splitter that splits the laser from the laser light source into a plurality of directions. Is desirable.

Further, in the above, the pair of lasers split by the beam splitter are incident on each individual galvanometer mirror and further reflected, and the pair of outer peripheral arc portions of the notch portion of the silicon wafer are further reflected by the respective reflected lasers. It is desirable to irradiate each of them and / or to irradiate the chamfered slope on the front side and the chamfered slope on the back side of the silicon wafer, respectively.

Furthermore, in order to achieve the above object, the 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, wherein the silicon wafer is repaired. A step of attaching the silicon wafer to a wafer feed unit that holds at least one of rotation, movement, and tilt so as to be possible, and a step of grinding the surface of the silicon wafer held by the wafer feed unit with a grinding unit. And a step of irradiating the surface of the ground silicon wafer with a laser using a laser irradiation repair device, and in the use of the laser irradiation repair device, the laser irradiation repair device is provided before laser irradiation. Based on the step of measuring the surface state and / or shape of the silicon wafer held in the wafer feed unit by the measuring device and the measurement data by the measuring device by the control device provided in the laser irradiation repair device. The ground surface of the silicon wafer is irradiated with the laser by the laser irradiation unit provided in the laser irradiation repair device according to the step of setting the irradiation conditions and / or the irradiation atmosphere of the silicon wafer and the setting conditions of the control device. The step of measuring the surface condition of the silicon wafer during and / or after irradiation with the measuring device and confirming whether or not the surface of the silicon wafer has been repaired, and the case of repairing. Is characterized in that it has a step of terminating the laser irradiation and, if not repaired, restarting or continuing the laser irradiation until the repair is confirmed.

Further, in the step of irradiating the ground surface of the silicon wafer with a laser by the laser irradiation unit provided in the laser irradiation repair device, the outer peripheral edge portion chamfered by the grinding of the silicon wafer and / Alternatively, it is desirable to irradiate the notch with a laser.

Further, in the step of irradiating the ground surface of the silicon wafer with a laser by the laser irradiation unit provided in the laser irradiation repair device, the displacement mechanism of the laser irradiation unit, the output characteristics of the laser light source, and the like. It is desirable to control at least one of the operations of the optical mechanism.

Further, in the step of irradiating the ground surface of the silicon wafer with a laser by the laser irradiation unit provided in the laser irradiation repair device, the laser from the laser light source of the laser irradiation unit is split into a plurality of parts. It is desirable to irradiate a plurality of points on the silicon wafer from various directions with each of the dispersed lasers.

Further, in the above, the pair of lasers split by the beam splitter are incident on the individual galvanometer mirrors and further reflected, and the pair of outer peripheral arc portions of the notch portion of the silicon wafer are respectively reflected by the reflected lasers. It is desirable to irradiate and / or to irradiate the chamfered slope on the front side and the chamfered slope on the back side of the silicon wafer, respectively.

Further, in the above, when irradiating the arc portion of the concave bottom portion of the notch portion of the silicon wafer with the laser, the curvature of the arc portion of the concave bottom portion of the notch portion is maintained while the laser irradiation direction is kept constant. It is desirable that the center of the radius is placed on the optical path of the laser L and the silicon wafer itself is rotated and irradiated with the center of the radius of curvature as the center.

Further, in the above, when irradiating the straight line portion of the recess of the notch portion of the silicon wafer with the laser, the silicon wafer is moved toward the straight line portion while the laser irradiation direction is held orthogonal to the straight line portion. It is desirable to configure it so that it moves linearly along it.

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 status of the damaged portion due to the grinding process are confirmed and grasped, and then the control device irradiates the laser. Efficient wafer surface repair and flattening can be performed by controlling the laser irradiation conditions and atmosphere through the unit's displacement mechanism, optical mechanism, temperature control device, etc., and performing effective laser irradiation. Is possible. Further, since the laser scanning method according to the shape can be executed, proper repair can be performed in a short time.

That is, more specifically, (1) the surface condition after grinding is examined before the laser irradiation, and the laser irradiation is performed under the corresponding conditions, so that the surface modification can be efficiently and effectively performed. (2) The throughput is improved by performing surface treatment in a short time (10 seconds or less) using a laser. (3) No polishing thread, polishing liquid / chemicals, cleaning / drying process is required, and the environmental load is small. The process is possible, (4) Since it is performed in an environment such as atmospheric pressure and normal temperature, there is no need for other raw materials that must be added. (5) Laser irradiation is a kind of heat treatment modification and is a substance. Since it does not involve the removal of laser, the original size can be maintained, (6) cracks and strains can be completely repaired, so the mechanical strength of the work piece is improved, the yield in the post-process is improved, and many other effects are achieved. Obtainable.

Front view showing a main part of an embodiment of a silicon wafer surface grinding / repairing apparatus according to the present invention. Top view showing the main part of the whole apparatus in one embodiment Partially enlarged side view showing a state during processing of the outer peripheral fine grinding spindle portion in one embodiment. Cross-sectional view showing the shape of a silicon wafer after processing by the prior art Sectional drawing which shows the shape of the silicon wafer after processing in one Embodiment Explanatory drawing which shows the notch part provided in the silicon wafer and the process of fine grinding chamfer processing thereof. A block diagram showing the relationship between the main components of an embodiment of the laser irradiation repair device in the present invention. Image diagram showing various examples of the measuring apparatus provided in the laser irradiation repair apparatus of this invention. Image diagram showing an example of a form in which laser irradiation is performed according to the shape of a notch portion of a silicon wafer by the laser irradiation repair device of the present invention. Image diagram showing some examples of a form in which laser irradiation is performed according to the shape of a notch portion of a silicon wafer by the laser irradiation repair device of the present invention. Image diagram for explaining an example of laser irradiation conditions in the present invention Flow chart of laser irradiation repair method according to the present invention Enlarged image diagram for comparing the state before and after laser irradiation of the surface layer of the ground silicon wafer Explanatory drawing showing the repair principle by laser irradiation of the surface layer of a silicon wafer A photomicrograph of a notch portion of a silicon wafer before laser irradiation in a state where grinding is completed by the grinding repair device and method according to the present invention. A micrograph of the region after grinding of the notch portion of the silicon wafer shown in FIG. 15 after performing laser irradiation treatment by the grinding repair device and method according to the present invention.

Hereinafter, embodiments 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 a grinding repair device 1 on the surface of a silicon wafer according to an embodiment of the present invention.

The grinding / repairing device 1 includes a wafer feed unit 20, a grinding unit 10, and a laser irradiation repairing device 100. The wafer feed unit 20 attaches a silicon wafer W to the wafer feed unit 20 and holds the silicon wafer W so that at least one of rotation, movement, and tilt can be performed. The grinding unit 10 grinds the surface of the silicon wafer W held by the wafer feed unit 20, particularly the outer peripheral edge portion and the notch portion thereof. The laser irradiation repair device 100 irradiates the surface of the ground silicon wafer W with a laser to flatten the surface roughness and repair the processed altered layer.

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

The grinding unit 10 includes a grindstone rotating unit 50, a controller that controls the operation of each part of the grinding unit, and the like.

The drive device 12 of the wafer feed unit 20 includes a wafer supply / storage unit, a wafer cleaning / drying unit, a wafer transfer means, etc. (not shown), and an X-axis base 21 and two Xs mounted on the main body base 11. It has an X-axis table 24 that is moved in the X-direction in the figure by an X-axis drive mechanism 25 including a shaft guide rail 22, 22, four X-axis linear guides 23, 23, ..., A ball screw and a stepping motor.

The X table 24 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, ..., A ball screw and a stepping motor (not shown). The Y table 28 to be used is incorporated.

The Y table 28 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 including a ball screw and a stepping motor. Z table 31 is incorporated.

A θ-axis motor 32 and a θ-spindle 33 are incorporated in the Z-table 31, and a wafer table 34 on which a wafer W (plate-shaped workpiece) is sucked and placed is attached to the θ-spindle 33. Is rotated in the θ direction in the figure around the axis of rotation.

Further, at the lower part of the wafer table 34, a truing grindstone 41 (hereinafter referred to as a truer 41) used for truing the grindstone for finishing chamfering the peripheral edge of the wafer W is attached concentrically with the rotation axis of the wafer table.

By the 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.

An outer peripheral rough grinding wheel 52 is attached to the outer peripheral rough grinding device 60 of the grindstone rotation unit 50, and an outer peripheral grindstone spindle 51 that is rotationally driven around an axis by an outer peripheral grindstone motor (not shown) is provided. Further, the grindstone rotation unit 50 has an upper outer circumference fine grinding spindle 54 and an upper outer circumference fine grinding motor 56 attached to a turntable 53 arranged above. Similarly, the turntable 53 is provided with a lower outer peripheral fine grinding spindle 57 and a lower outer peripheral fine grinding motor (not shown) via a lower fixed frame 59 (not shown in FIG. 1). Further, the turntable 53 includes a notch rough grinding wheel 61, a notch rough grinding spindle 62, a notch rough grinding motor 63, a notch fine grinding wheel 64, a notch fine grinding spindle 65, and a notch fine grinding motor 66. And are provided.

FIG. 2 is a plan view showing a main part of the entire grinding / repairing apparatus 1, and the supply / recovery unit supplies the wafer W to be chamfered from the wafer cassette 70 and transfers the chamfered wafer W to the wafer cassette 70. to recover. This operation is performed by the supply / recovery robot 40. The wafer cassette 70 is set on the cassette table 71, and a large number of wafers to be chamfered are stored. The supply / recovery robot 40 takes out wafers W one by one from the wafer cassette 70, and stores the chamfered wafer W in the wafer cassette 70.

The supply / recovery robot 40 is provided with a 3-axis rotary type transfer arm 80, and the transfer arm 80 is provided with a suction pad (not shown) on the upper surface thereof. The transfer arm 80 holds the wafer W by vacuum suctioning the back surface of the wafer W with a suction pad. That is, the transfer arm 80 of the supply / recovery robot 40 can move back and forth, move up and down, and rotate while holding the wafer W, and conveys the wafer W by combining these operations.

The grinding unit 10 is arranged on the front surface portion, and performs all processing of chamfering the outer periphery of the wafer W, that is, from rough processing to finishing processing. The grinding unit 10 is composed of a wafer feed unit 20 and a grindstone rotation unit 50 shown in FIG.

As shown in FIG. 1, the upper outer peripheral fine grinding spindle 54 and the lower outer peripheral fine grinding spindle 57 are in a state where the rotation axis is tilted by 3 to 15 °, preferably 6 to 10 ° with respect to the rotation axis of the wafer W. Finish the outer circumference chamfering. As a result, helical grinding is performed, and although weak grinding marks are generated in the chamfered portion of the wafer W in the oblique direction, the effect of improving the surface roughness of the chamfered portion can be obtained as compared with normal grinding. However, the grinding method in the grinding unit 10 provided in the grinding repair device 1 according to the present invention is not limited to such a helical grinding method, and a general grinding method along a direction parallel to the main plane of the wafer is also widely used. included.

FIG. 3 is an enlarged side view of a part of the outer peripheral fine grinding spindle portion, and also shows the state during processing. An upper outer peripheral grinding wheel (upper grinding wheel) 55-1 which is a chamfering grindstone for finishing and grinding the outer periphery of the wafer W is attached to the upper outer peripheral grinding wheel 54, and similarly, the lower outer peripheral grinding wheel 57 is attached to the lower outer peripheral grinding wheel 57. The rotation axis of the outer peripheral grinding wheel (lower grinding wheel) 55-2 is substantially concentric with the upper outer peripheral grinding wheel 55-1 with a gap of about 0.1 to 1 mm, which is smaller than the thickness of the wafer W. Can be attached to.

Further, the upper outer peripheral fine grinding grind 55-1 and the lower outer peripheral fine grinding grind 55-2 are driven by the upper outer peripheral fine grinding spindle 54 and the lower outer peripheral fine grinding spindle 57 so that the rotation directions are opposite, that is, opposite rotations. Will be done. The grinding groove for processing the wafer W is formed by the upper outer peripheral grinding wheel 55-1 and the lower outer peripheral grinding wheel 55-2. The gap is provided substantially at the center of the grinding groove in the direction of the rotation axis.

The wafer processing process is performed in the order of slicing → chamfering → wrapping → etching → donor killer → fine chamfering, and various cleanings are used to remove stains between the processes. Silicon etc. is hard and brittle, and if the edge of the outer circumference of the wafer remains sharp during slicing, it will easily crack or chip during handling such as transportation and alignment in the subsequent processing process, and fragments will damage the wafer surface. Or pollute. In order to prevent this, in the chamfering process, the outer peripheral end face of the cut wafer is chamfered with a chamfering grindstone coated with diamond.

The chamfering step may be performed after the wrapping step. At this time, it is also included to match the diameters of the outer circumferences with variations, to match the width of the orientation flat (OF), and to match the dimensions of a minute notch called a notch.

FIG. 3 also shows the state during processing of the outer peripheral fine grinding spindle portion, and the rotation direction and force of the upper outer peripheral fine grinding spindle 54 and the lower outer peripheral fine grinding spindle 57, the inflow and retention of the coolant liquid, and the like. It shows the relationship of chip discharge. The upper outer peripheral fine grinding spindle 54 rotates counterclockwise (the direction indicated by arrow A, that is, rotates from left to right in the drawing) and tilts clockwise with respect to the rotation axis of the wafer W, that is, downward from left to right in the drawing. Since it is inclined to, a force is applied to the wafer W as shown by arrow A. Since the center of the wafer W is held and the outer circumference is a free end, the wafer W can be bent downward by a component force. On the other hand, the lower outer peripheral fine grinding spindle 57 rotates clockwise (the direction indicated by the arrow B, that is, rotates from right to left in the drawing) and is inclined upward from right to left in the drawing. Force is applied as shown by arrow B.

Since the gap between the upper outer peripheral grinding wheel 55-1 and the lower outer peripheral grinding wheel 55-2 is symmetrical in the center in the direction of the rotation axis, the wafer W and the upper outer peripheral grinding wheel 55-1 and the lower outer peripheral grinding wheel 55-1 are finely ground. The contact area with the grindstone 55-2 is equal. Therefore, the respective grinding resistors are balanced and do not generate a force that bends the wafer W. As a result, the wafer W is not bent and deformed from the center to the tip, and the shape accuracy of the machined surface due to the bending deformation is not affected.

Arrows C and D indicate the inflow direction of the coolant liquid, and the upper side of the wafer W is from the left side in FIG. 3 and the outer circumference of the wafer W along the counterclockwise direction which is the rotation direction of the upper outer peripheral grinding wheel 55-1. Inflow from to the center. The lower side flows from the right side and toward the center from the outer circumference of the wafer W along the clockwise direction, which is the rotation direction of the lower outer circumference fine grinding wheel 55-2.

FIG. 4 is a cross-sectional view showing the shape of the wafer W after processing by the conventional technique, showing the shape of the wafer W at the cutting position processed by a normal outer peripheral grinding wheel, and has a thickness of 740 μm and an upper surface (surface). A1 is 340 μm, B1 is 300 μm, θ1 is 43 °, A2 on the lower surface (back surface) is 250 μm, B2 is 190 μm, θ2 is 40 °, and the wafer W is bent downward to chamfer the front side. The symmetry between the slope w2 and the chamfered slope w3 on the back side was broken.

On the other hand, FIG. 5 is a cross-sectional view showing the shape of the wafer W after processing according to the embodiment of the present invention. With respect to FIG. 4, the outer peripheral grinding wheel 55 is separated into upper and lower parts and the upper outer peripheral grinding wheel 55 -1, The shape of the wafer W when the lower outer circumference fine grinding wheel 55-2 is rotated in the reverse direction is shown. The thickness is 740 μm and the upper surface (front surface) A1 is 290 μm, B1 is 260 μm, θ1 is 44 °, while the lower surface (back surface) A2 is 290 μm, B2 is 240 μm, and θ2 is 42 °. The symmetry between the chamfered slope w2 and the chamfered slope w3 on the back side is improved, and the accuracy is improved.

An orientation flat (abbreviation for orientation flat) or a notch portion is often formed on the outer periphery of the silicon wafer W in order to facilitate determination of the crystal orientation and alignment of the wafer. Then, for these wafers, it is necessary to similarly perform fine grinding chamfering on the orientation flat or the notch portion.

FIG. 6 shows an example of the notch portion and the process of precision chamfering (finish chamfering) processing thereof. FIG. 6D shows a silicon wafer W and a notch portion wn formed at one location on the outer peripheral portion thereof. The notch portion wn has a substantially V-shaped notch shape, and both ends and the bottom portion on the outer peripheral side thereof have an arc shape.

6 (a) to 6 (c) show a step of performing fine grinding chamfering (finish chamfering) of the notch portion w, but before that, the outer peripheral portion of the silicon wafer W is subjected to an outer peripheral rough grinding grind 52. Rough grind chamfer. Next, a notch portion wn is formed at one location on the outer peripheral surface of the silicon wafer W by using the notch portion rough grinding wheel 61 shown in FIG. Next, as described above, the outer peripheral chamfered portion of the silicon wafer W is finely ground (finish ground) by the outer peripheral fine grinding wheel 55. Next, the turntable 53 shown in FIG. 1 is rotated to position the notch precision grinding wheel 64 at the machining position as shown in FIG. 6A. In this state, while rotating the notch portion fine grinding wheel 64 at high speed, the wafer W is fed in the X and Y directions as shown in FIGS. 6 (b) to 6 (c), thereby sequentially following the contour of the notch portion wn. Perform fine grinding chamfering. That is, the outer peripheral side corner portion of the notch portion wn shown in FIG. 6A is finely ground and chamfered in an arc shape with the notch portion fine grinding grindstone 64, and the notch portion wn is passed through the bottom portion as shown in FIG. 6B. Fine grinding chamfering is performed up to the outer peripheral corner on the opposite side shown in FIG. 6 (c). During this period, the wafer W is not rotated by θ, and the notch portion wn is finely ground and chamfered by feeding in the X and Y directions.

As described above, the rough grinding and fine grinding work of the chamfered slopes on the front side and the back side of the outer peripheral edge portion and the notch portion of the silicon wafer W by the grinding unit 10 in the grinding repair device 1 is completed.

Next, the configuration and operation of the laser irradiation repair device 100 in the grinding repair device 1 according to the present invention will be described with reference to FIG. 1 again. In the laser irradiation repair device 100, the outer peripheral edge portion and / or the notch portion is ground by the grinding unit 10 as described above, and the ground portion of the chamfered silicon wafer W is irradiated with a laser to flatten the surface roughness. Repairs the conversion and processing alteration layer. The laser irradiation repair device 100 includes a laser irradiation unit 101, a measuring device 102, and a control device 103.

In the displacement mechanism 120 mounted and supported by the laser irradiation unit 101 of the laser irradiation repair device 100, each component represented by reference numerals 121 to 133 is referred to by reference numerals 21 to 33 in the wafer feed unit 20 of the grinding unit 10. Since the configuration is the same as or equivalent to each component shown in the above, description thereof will be omitted here. With these components, the rotary table 135 is configured to be movable in the X, Y, and Z axis directions and to be rotatable about the axis of the θ spindle 133.

Further, a tilting stand 136 is mounted on the rotary table 135, and the laser irradiation unit 101 is placed on the tilting stand 136. The tilting pedestal 136 is held tiltably with respect to the rotary table 135 by the shaft support pin 137, and the cam 138 rotatably provided by the cam pin 139 is rotated by a pulse motor or the like (omitted in the figure). The tilting base 136 rotates about the shaft support pin 137. As a result, the laser irradiation unit 101 can be tilted in the vertical direction, and together with the movement in the X, Y, and Z axis directions and the rotation about the axis of the θ spindle 133, the laser irradiation unit 101 is directed toward the silicon wafer W. The laser irradiation direction can be continuously adjusted, which constitutes one of the means for changing the laser irradiation conditions. In the illustrated embodiment, the displacement mechanism 120 is configured to allow the laser irradiation unit 101 to move, rotate, and tilt with respect to the silicon wafer W, but it can be moved according to the purpose of use. It may be possible to enable at least one type of displacement operation of rotation and tilt.

The laser irradiation unit 101 irradiates a predetermined surface of the silicon wafer W after grinding with a laser, and in the embodiment shown in FIG. 1, the chamfered outer peripheral edge portion of the silicon wafer W and / Alternatively, it is configured to irradiate the notch portion 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 configured and illustrated so that the laser irradiation conditions can be changed. In the case of the embodiment, the relay mirror 101c, the collimator 101d, the mask 101e, the condensing lens 101f, the moving table 101g for adjusting the focal position, and the like are provided. In this case, the laser emitted from the laser light source 101a is turned by the relay mirror 101c, converted into a parallel luminous flux having a predetermined diameter by the collimator 101d, and then travels along the light-shielding mask 101e to proceed along the light-shielding mask 101e, and the condensing lens 101f. Converges to a predetermined position on the surface of the silicon wafer W to be irradiated. The condensing lens 101f is mounted on the moving table 101g for adjusting the focal position, and the position where the laser is converged matches the position to be irradiated on the silicon wafer W. The optical element constituting the optical mechanism 101b is not limited to the illustrated example, and includes at least one of a mirror, a galvano mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, a mask, and the like. Any configuration can be used as long as the laser irradiation conditions can be changed accordingly. The galvano mirror scans the laser on the surface to be irradiated by its rotation and vibration.

The laser irradiation repair device 100 further includes a measuring device 102 and a control device 103. Further, although not shown in FIG. 1, as required, as shown in FIG. 7, a temperature control device 104 for heating, cooling, etc. of the silicon wafer W and the like held in the wafer feed unit 20, and silicon. An atmosphere maintaining device 105 that keeps the gas composition and pressure of a predetermined processing region surrounding the wafer W within a predetermined range is also provided.

As shown in FIG. 1, the measuring device 102 has a silicon wafer W in the vicinity of a portion where the measuring instrument main body 102a should irradiate the laser of the silicon wafer W via the support column 102b attached to the Z table 31 of the wafer feeding unit 20. It is designed to be held in a non-contact state with. The measuring instrument main body 102a is configured so that the position can be adjusted on the support column 102b, and preferably the support column 102b is also configured to be appropriately movable so that the surface state (surface roughness, reflection) of a desired portion of the silicon wafer W is formed. It is configured to be measurable in properties, scattered light, etc.) and / or shape.

In such measurement of the surface condition of the silicon wafer W, first, in order to set the irradiation conditions and the irradiation atmosphere at the start of laser irradiation, the surface of the silicon wafer W after the grinding of the silicon wafer W is completed and before the laser irradiation is performed. Measure the condition etc. In addition, measurement should be performed during laser irradiation to prevent over-irradiation of the laser and to monitor the suitability of the irradiation status, and measurement should be performed after irradiation to determine the suitability of the irradiation result. Is desirable.

It is desirable that the measuring device 102 measures the surface state and / or shape of the silicon wafer W by a non-destructive method. Specific measuring means include, for example, an image measuring means, a capacitance change measuring means, and a droplet contact angle. From among measuring means, Raman spectroscopic measuring means, surface roughness meter, acoustic measuring means, eddy current characteristic measuring means, reflectance measuring means, X-ray Lang method measuring means, electron beam diffraction measuring means, SEM measuring means, etc. It is also recommended to use one of the chosen ones or a combination of two or more of them. Some of these will be described with reference to FIG.

FIG. 8A uses an image measuring means, and in order to measure the surface roughness of, for example, the chamfered slope w2 on the front side of the silicon wafer W, laser light, light in a desired wavelength range, etc. from the measurement light source 140, etc. Is irradiated on the chamfered slope w2, the image is imaged by a detector 141 such as a hyperspectral camera, surface roughness and the like are detected by the image analysis, and irradiation from the laser irradiation unit 101 is performed based on the detection result. The conditions and the like are selected and controlled to flatten the chamfered slope w2 and repair the work-altered layer. A machine learning means based on a trial experiment, comparison with a control sample, or the like may be adopted for determining the surface roughness or the like by such image analysis.

FIG. 8B is a measuring device using a capacitance change measuring means. In this case, the electrodes 142 are arranged close to the outer peripheral end faces w1 of the silicon wafer W and the chamfered slopes w2 and w3 on the front and back sides, and a voltage is applied from the DC power supply 143 between the silicon wafer W and the electrodes 142. By detecting the attractive force F due to the static electricity, the surface roughness of the outer peripheral end surface w1, the chamfered slopes w2 and w3 on the front and back sides, and the like are detected.

FIG. 8C is a measuring device using the liquid drop contact angle measuring means. In this case, an appropriate droplet 144 is attached to, for example, the chamfered slope w2 on the front side of the silicon wafer W, and the contact angle 144a of the droplet 144 with respect to the chamfered slope w2 is measured. This is based on the fact that the wettability of the chamfered slope w2 changes according to the level of surface roughness, and the contact angle 144a of the droplet 144 also changes accordingly.

In addition to these, as the measuring means, for example, a Raman spectroscopic measuring means can be used, although not shown. In that case, by measuring the strain from the Raman shift, it is possible to detect the change in the crystal state inside the silicon wafer W, determine the level of deterioration due to grinding based on it, and based on the result, the laser irradiation conditions, etc. Can be optimally controlled. In addition, it is also possible to detect using ultrasonic waves or AE waves that do not cause destruction by acoustic measuring means, or to use a non-contact type or contact type surface roughness meter, and by means of eddy current characteristic measuring means. It is also possible to measure the quality of conductivity of the chamfered slope and the like to determine the level of deterioration due to grinding. Furthermore, the scale and status of alteration by grinding the surface of the silicon wafer W using various known means such as reflectance measuring means, X-ray rung method measuring means, electron beam diffraction measuring means, SEM measuring means, and the like. Is determined, and the laser irradiation conditions and the like can be optimally and efficiently adjusted and controlled based on the result.

Next, the control device 103 of the laser irradiation repair device 100 has a function of controlling the laser irradiation condition and / or the irradiation atmosphere based on the measurement data by the measurement device 102. In the embodiment shown in FIG. 1, the control device 103 is provided in the substrate of the grindstone rotation unit 50, but the installation location is free, and as a part of the control device of the entire grinding repair device 1. It may be configured.

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

As the temperature control device 104, as described above, the silicon wafer W is heated and cooled to eliminate the influence of thermal stress, and the laser irradiation effect is promoted and optimized, and the wafer feed unit 20. In order to eliminate the influence of thermal stress on the laser irradiation unit 101 and the laser irradiation unit 101, those for keeping their temperatures constant are provided.

Further, an atmosphere maintaining device 105 for maintaining the gas composition and pressure of a predetermined processing region surrounding the silicon wafer W within a predetermined range is provided so as to form and maintain an atmosphere such as gas components and pressure suitable for the processing conditions.

A shield mechanism for preventing laser leakage from the processing region is provided, and such a shield mechanism is also subject to control by the control device 103, if necessary.

Next, an example of an irradiation form capable of effective, efficient, and short-time repair in laser irradiation according to the surface condition and shape of the silicon wafer after grinding by the laser irradiation repair device 100 will be described. In that case, the irradiation conditions are generally changed according to the surface condition by changing the output characteristics of the laser, the energy density, and the like by the laser light source 101a and the optical mechanism 101b. Further, the irradiation is generally changed according to the shape of the irradiation region by changing the position and orientation of the laser irradiation unit and / or the silicon wafer (workpiece), with respect to the depth direction of the notch portion. This is done by changing the orientation of the silicon wafer side and the orientation of the mirror in the optical mechanism. However, the present invention is not limited to these, and these various means can be appropriately selected or combined according to the situation.

FIG. 9 shows an example of the irradiation mode according to the present invention that matches the shape of the chamfered notch portion of the silicon wafer W. More specifically, in FIG. 9 (a), two locations of the chamfered notch portion wn on the outer peripheral side arc portions w4 and w5 are simultaneously and in parallel, and in FIGS. 9 (b) [(a), FIG. As shown in [enlarged cross-sectional view along BB], the chamfered slope w2 on the front side, the chamfered slope w3 on the back side, and the end face w1 of the notch recess are also configured to be capable of continuous laser irradiation. It is shown. In FIG. 9A, for convenience of explanation, only the notch portion wn of the silicon wafer W is enlarged and drawn.

That is, specifically, a pair of lasers L11a and L12a spectroscopically split by the beam splitter 101m are incident on the individual galvanometer mirrors 101n and 101o, respectively, and further reflected, and the notch portion is formed by the reflected lasers L11b and L12b, respectively. It is configured to irradiate a pair of outer peripheral arc portions w4 and w5 of wn, respectively. At that time, by rotating or reciprocating the galvanometer mirrors 101n and 101o, the directions of the reflected lasers L11b and L12b are changed, and the chamfered slopes w2 on the front side and the chamfered slopes on the back side of the outer peripheral arc portions w4 and w5 are scanned. The w3 and the outer peripheral end face w1 are efficiently irradiated with a laser in parallel at the same time (FIG. 9 (b)). In the illustrated embodiment, the galvanometers 101n and 101o are parabolic mirrors and are adapted to focus on the outer peripheral arc portions w4 and w5, which are irradiation targets. This focal position can be adjusted by adjusting the luminous flux of the laser in the stage before it is incident on the beam splitter 101m, for example, by adjusting the moving table 101g of the condensing lens 101f shown in FIG. 7. is there. In FIG. 9A, 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. is there. The uneven shape drawn on the chamfered slope w2 on the front side and the chamfered slope w3 on the back side in FIG. 9B is an enlarged image of the surface roughness generated by grinding.

If the focus of the galvanometer mirrors 101n and 101o is aligned with the chamfered slope of the outer periphery of the rotating silicon wafer W by using such an optical mechanism, the outer periphery of the silicon wafer W is not limited to the notch portion. The chamfered slopes and end faces on the front and back sides of the above can also be efficiently and effectively repaired, for example, the entire outer circumference can be quickly repaired in less than 10 seconds. As shown in the figure, a splitter 101l and a beam splitter 101k for adjusting the luminous flux are provided in the stage prior to the beam splitter 101m in FIG. 9A, and the previous stage is described in FIG. 7. It is assumed that each optical element connected to the optical mechanism 101b and shown in FIG. 9A is also included in the optical mechanism 101b, and all of them constitute the optical mechanism in the present invention.

Further, FIG. 10A shows another configuration example in which the chamfered slope w2 on the front side, the chamfered slope w3 on the back side, and the end surface w1 on the outer periphery of the silicon wafer W are simultaneously irradiated. That is, the pair of lasers L13a and L14a spectroscopically split by the beam splitter 101h are incident on the individual galvanometers 101i and 101j, respectively, and further reflected, and the front side of the silicon wafer W is chamfered by the reflected lasers L13b and L14b, respectively. An example of configuration in which the slope w2 and the chamfered slope w3 on the back side are irradiated is shown. 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 the beam splitter in FIG. 10 (a). It passes through 101h and is split into two lasers L13a and L14a. Of these, the laser L13a is reflected by the galvano mirror 101i placed on the optical path and irradiates the chamfered slope w2 on the front side of the silicon wafer W. By rotating the galvano mirror 101i or rotating it within a predetermined angle range, the slope w2 is irradiated in a scanning manner by the reflected laser L13b. Similarly, the laser L14a is reflected by the galvano mirror 101j placed on the optical path, and irradiates the chamfered slope w3 on the back side of the silicon wafer W in a scanning manner. At this time, in order to irradiate the outer peripheral end face w1 of the silicon wafer W as well, the arrangement of each optical element or the like is adjusted so that the end face w1 is included in the scanning range by the galvanometer mirror 101i and / or 101j. May be good. Alternatively, the entire irradiation target region may be irradiated by changing the orientation of the silicon wafer W during the irradiation period. In the example shown in FIG. 10A, the transmission laser L15 of the beam splitter 101h irradiates the end face w1 on the outer periphery of the silicon wafer W. In the case of this embodiment, the beam splitter 101h, galvanometers 101i and 101j are also included in the components of the optical mechanism 101b.

Next, FIG. 10B shows a suitable irradiation mode when irradiating the arc portion w6 at the bottom of the recess portion w of the notch portion wn of the silicon wafer W with the laser L. In this case, 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 (in other words, the laser L is set to pass through the center O1). The silicon wafer W itself is rotated and irradiated around this O1. Alternatively, the laser irradiation direction may be swirled around the center O1 in a state where the center O1 is placed on the optical path of the laser L. As a result, the laser L continues to be irradiated in a state of being substantially orthogonal to the curved surface of the arc portion w6, and an effective and efficient irradiation effect can be obtained. In order to rotate the silicon wafer W around the center O1 as described above, for example, an arc at the bottom of the recess in the notch portion at the center of rotation of the wafer table 34 of the wafer feed unit 20 of the grinding repair device 1 shown in FIG. The center O1 of the radius of curvature of the portion w6 is positioned so that the wafer table 34 is rotated.

Next, FIG. 10C shows a suitable irradiation mode when irradiating the straight line portion w7 (also in the case of w8) of the recess of the notch portion wn of the silicon wafer W with the laser L. In this case, the silicon wafer W is linearly moved along the direction of the straight line portion w7 while the irradiation direction of the laser L is held orthogonal to the straight line portion w7. As a result, the laser L is continuously irradiated in a state orthogonal to the plane of the straight line portion w7, and an effective and efficient irradiation effect can be obtained. In order to linearly move the silicon wafer W along the direction of the straight line portion w7, for example, the straight line is used by using the X table 24 and the Y table 28 of the wafer feed unit 20 of the grinding repair device 1 shown in FIG. It can be linearly moved along the direction of the portion w7.

FIG. 11A shows an enlarged cross-sectional view of the chamfered portion of the outer peripheral portion of the silicon wafer W to be laser-irradiated according to the present invention, and FIG. 11B shows a plan view of the notch portion. .. To give an example of specifications of suitable irradiation conditions for such an irradiation target, the laser wavelength λ = 532 nm and the pulse width = 3 to 7 ns (generally 10 ns or less. However, the surface damage of the silicon wafer is large and deep. In this case, up to about 50 ns may be required.) Energy per pulse = 60 to 80 μJ, energy density = 0.6 to 0.8 J / cm ² (generally 0.24 to 1.44 J) (Range of / cm ² ), irradiation area = 0.5 mm × 0.5 mm, atmospheric pressure = atmospheric pressure.

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

As shown in FIG. 12, in the method according to the present invention, first, (1) the silicon wafer W is mounted on a wafer feed unit 20 that holds the silicon wafer W so that at least one of rotation, movement, and tilting can be performed. Perform the process of mounting.

Next, (2) the step of grinding the surface of the silicon wafer W held by the wafer feed unit 20 by the grinding unit 10 is executed.

Next, (3) before the laser irradiation by the laser irradiation repair device 100, the surface state and / or shape of the silicon wafer W held by the wafer feed unit 20 is determined by the measuring device 102 provided in the laser irradiation repair device. Perform the step of measuring.

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

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

Next, (6) the measuring device 102 measures the surface state of the silicon wafer during and / or after the laser irradiation, and executes a step of confirming whether or not the surface of the silicon wafer has been repaired.

Next, (7) the step of ending the laser irradiation when the repair is performed, and restarting or continuing the laser irradiation until the repair is confirmed if the repair is not performed is executed.

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. Therefore, the laser irradiation unit 101 provided in the laser irradiation repair device 100 can be used to perform the laser irradiation. In the step of irradiating the ground surface of the wafer W with a laser, the operation of irradiating the outer peripheral edge portion and / or the notch portion chamfered by the grinding of the silicon wafer W with the laser can be preferably performed.

Further, when the method of the present invention is used, in the step of irradiating the laser, as described above, 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). At least one of (direction, light flux diameter, scanning range, frequency, etc.) is controlled.

Further, in the case of the method of the present invention, in order to irradiate the laser according to the shape of the irradiation portion of the silicon wafer W acquired by the measuring device 102, a plurality of lasers from the laser light source 101a of the laser irradiation unit 101 are used as described above. It is possible to efficiently perform the irradiation operation on the outer peripheral portion and the notch portion having different shapes by irradiating a plurality of locations of the silicon wafer W from various directions with each of the dispersed lasers.

Further, in the case of the method of the present invention, as described with reference to FIG. 9, a pair of lasers L11a and L12a spectroscopically split by the beam splitter 101m are incident on the individual galvanometer mirrors 101n and 101o, respectively, and further reflected, respectively. The reflective lasers L11b and L12b can simultaneously irradiate the pair of outer peripheral arc portions w4 and w5 of the notch portion wn of the silicon wafer, to the notch portion where efficient and good irradiation has been difficult in the past. It is possible to efficiently perform the irradiation operation of.

Further, when the method of the present invention is used, as described with reference to FIG. 10A, a pair of lasers L13a and L14a dispersed by the beam splitter 101h are incident on the individual galvanometers 101i and 101j, respectively, and further reflected. It is possible to simultaneously irradiate the chamfered slope w2 on the front side and the chamfered slope w3 on the back side of the silicon wafer by the respective reflection lasers L13b and L14b, and it has been difficult to perform efficient and good irradiation on both the front and back sides. It is possible to efficiently perform the irradiation operation on the chamfered slope.

Further, when the method of the present invention is used, as described with reference to FIG. 10B, when the laser L is irradiated to the arc portion w6 at the bottom of the recess of the notch portion wn of the silicon wafer W, the irradiation direction of the laser L is set. While being held constant, 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, and the silicon wafer W itself is irradiated while rotating around this O1. This is possible, and it is possible to efficiently perform an irradiation operation on the arc portion of the bottom of the recess of the notch portion wn, which has been difficult to perform efficient and good irradiation in the past.

Further, when the method of the present invention is used, as described with reference to FIG. 10 (c), when the laser L is irradiated to the linear portion w7 (w8) of the recess of the notch portion wn of the silicon wafer W, the laser L is irradiated. While the direction is held orthogonal to the straight portion w7 (w8), the silicon wafer W can be linearly moved along the direction of the straight portion w7 (w8), and conventionally, efficient and good irradiation can be performed. It is possible to efficiently perform the irradiation operation on the straight portion of the recess of the notch portion wn, which was difficult to perform.

FIG. 13 shows a case where the unevenness of the surface layer generated when the surface of the silicon wafer W is ground is flattened and repaired by laser irradiation in order to explain the repair effect by laser irradiation on the surface of the silicon wafer of the present invention. The image diagram of is shown. That is, as shown in FIG. 13A, when the surface of the silicon wafer W is ground, the surface region of the original single crystal layer w9 becomes a work-altered layer and becomes a rough surface having unevenness w10. When the rough surface is irradiated with the laser L, the irradiated surface region is melted and becomes a flat surface w11 as shown in FIG. 13 (b) due to surface tension, and the region near the surface is single crystallized again and repaired. Will be done. The principle will be described with reference to FIG.

As shown in FIG. 14A, in the ground portion of the silicon wafer, the layer near the surface of the processed portion has crystal defects due to machining, and is a processed alteration layer such as an amorphous layer or a dislocation layer. Since the laser absorption rate of this processed alteration layer portion is significantly higher than that of the single crystal region, the processed altered layer is melted by irradiation with a laser (nanosecond pulse laser) as shown in (b), and the processed altered layer is changed to (c) by heat conduction. As shown, the molten region expands and the surface of the molten region is flattened by surface tension. When the laser irradiation is stopped, as shown in (d), a liquid phase epitaxial crystal grows using the single crystal region as a seed, whereby the lattice defects of the crystal generated during the grinding process are eliminated and (e). ) Is restored to the original single crystal (see Patent Document 4).

Finally, with reference to FIGS. 15 and 16, by comparing the surface states before and after irradiating the surface of the silicon wafer after grinding with a laser by the grinding / repairing apparatus and method according to the present invention. , The effect of the present invention will be described. FIG. 15 is a micrograph of a notch portion of a silicon wafer before irradiation with a laser in a state where the grinding process has been completed by the grinding / repairing apparatus and method according to the present invention, and FIG. 16 is a silicon wafer shown in FIG. It is a micrograph after performing a laser irradiation treatment on the region after grinding of the notch portion of the above by the grinding repair apparatus and method according to the present invention.

As shown in FIG. 15, fine grinding marks (scratch marks or streaks) are formed on the ground surface including the chamfered slope w2 of the notch portion wn of the silicon wafer W before irradiation with the laser in the state where the grinding process is completed. It is formed. That is, the entire region from one outer peripheral arc portion w4 of the notch portion wn to the straight portion w7, the arc portion w6 at the bottom of the recess, the other straight portion w8, and the other outer peripheral arc portion w5. , Grinding marks consisting of a large number of fine, substantially parallel uneven streaks are formed, resulting in a rough surface condition. Such grinding marks are similarly formed not only on the notch portion wn shown in the photograph but also on the outer peripheral end surface and the outer peripheral chamfered slope of the silicon wafer W. In addition, the damage caused by grinding is not limited to the surface that can be observed with a microscope as described above, but as described above, the region from the surface to a predetermined depth becomes an amorphous layer or a dislocation layer and becomes a processed alteration layer to the inside. It extends.

FIG. 16 shows a state after the laser irradiation treatment is performed on the surface region of the notch portion of the silicon wafer shown in FIG. 15 after grinding by the grinding repair device and method according to the present invention. That is, after the laser irradiation treatment, as described above, the notch portion wn passes from one outer peripheral side arc portion w4 to the straight portion w7, the arc portion w6 at the bottom of the recess, and the other straight portion w8, and then the other outer circumference. It can be visually recognized that the surface of the region up to the side arc portion w5 is a smooth and glossy flat surface as a whole. That is, by irradiating the ground surface with the laser under irradiation conditions such as appropriate intensity from various directions while making the laser correspond to the shape and surface condition of the notch portion wn, usually uniform and good irradiation is performed. According to the present invention, proper laser irradiation is performed evenly, evenly, efficiently, quickly and effectively on the notch portion wn, which is difficult to perform, and damage due to grinding is performed based on the repair principle. It will be repaired.

The present invention has the above configuration, and by measuring the surface condition and shape of the silicon wafer with the measuring device, the scale and status of the damaged portion due to the grinding process are confirmed and grasped, and then the control device irradiates the laser. Efficient wafer surface repair and flattening can be performed by controlling the laser irradiation conditions and atmosphere through the unit's displacement mechanism, optical mechanism, temperature control device, etc., and performing effective laser irradiation. Is possible. Further, since the laser scanning method according to the shape can be executed, proper repair can be performed in a short time.

L ... Laser W ... Silicon wafer (work material)
w1 ... Outer circumference or end surface of notch recess w2 ... Front side chamfered slope w3 ... Back side chamfered slope w4, w5 ... Outer peripheral arc portion w6 of notch portion ... Arc portion w7, w8 ... Notch portion at bottom of recess Straight line portion w9 of the recessed portion w9 ... Single crystal layer w10 ... Concavo-convex w11 ... Flat surface wn ... Notch portion O1 ... Center of curvature radius of the arc portion at the bottom of the recessed portion of the notch portion O2, O3 ... Center of radius of curvature 1 ... Grinding repair device 10 ... Grinding unit 11 ... Main body base 12 ... Wafer feed unit drive device 20 ... Wafer feed 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 Rails 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 recovery robot 41 ... Turer 50 ... Grinding unit 51 ... Outer circumference Grinding spindle 52 ... Outer peripheral coarse grinding grind 53 ... Turntable 54 ... Upper outer peripheral fine grinding spindle 55 ... Outer peripheral fine grinding grind 55-1 ... Upper outer peripheral fine grinding grind (upper outer grinding grind)
55-2 ... Lower outer circumference fine grinding wheel (lower grinding wheel)
56 ... Upper outer peripheral fine grinding motor 57 ... Lower outer peripheral fine grinding spindle 59 ... Lower fixed frame 60 ... Outer peripheral rough grinding device 61 ... Notch rough grinding wheel 62 ... Notch rough grinding spindle 63 ... Notch rough grinding motor 64 ... Notch Fine grinding wheel 65 ... Notch fine grinding spindle 66 ... Notch fine grinding motor 70 ... Wafer cassette 71 ... Cassette table 80 ... Conveying arm 100 ... Laser irradiation repair device 101 ... Laser irradiation unit 101a ... Laser light source 101b ... Optical mechanism 101c ... Relay mirror 101d ... Collimeter 101e ... Mask 101f ... Condensing lens 101g ... Moving table for adjusting focus position
101h ... Beam splitter 101i, 101j ... Galvano mirror 101k ... Beam splitter 101l ... Polarizer 101m ... Beam splitter 101n, 101o ... Galvano mirror 102 ... Measuring device 102a ... Measuring device main body 102b ... Support 103 ... Control device 104 ... Temperature control device 105 ... Atmosphere maintenance device 120 ... Displacement mechanism 135 ... Rotating table 136 ... Tilt pedestal 137 ... Shaft pin 138 ... Cam 139 ... Cam pin 140 ... Measurement light source 141 ... Detector 142 ... Electrode 143 ... DC power supply 144 ... Droplet 144a ... Contact Horn

Claims (7)

A grinding and repair device for the surface of silicon wafers.
A wafer feed unit that mounts the silicon wafer and holds it so that it can rotate, move, and tilt at least one of them.
A grinding unit that grinds the surface of the silicon wafer held by the wafer feed unit, and
A laser irradiation repair device for irradiating the surface of the ground silicon wafer with a laser is provided.
The laser irradiation repair device
A measuring device for measuring the surface condition and / or shape of the silicon wafer held in the wafer feed unit, and
A laser irradiation unit that irradiates the ground surface of the silicon wafer with a laser,
A displacement mechanism that supports the laser irradiation unit so that at least one of rotation, movement, and tilt can be displaced with respect to the silicon wafer held by the wafer feed unit.
A control device that controls the laser irradiation conditions and / or the irradiation atmosphere based on the measurement data obtained by the measuring device.
A device for grinding and repairing the surface of a silicon wafer, which comprises. The measuring device for measuring the surface state and / or shape of the silicon wafer is 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, and the like. It is composed of any one or a combination of two or more selected from vortex current characteristic measuring means, reflectance measuring means, X-ray Lang method measuring means, electron beam diffraction measuring means, and SEM measuring means. The grinding and repairing apparatus for the surface of a silicon wafer according to claim 1. The laser irradiation unit has an optical mechanism including at least one of a mirror, a galvano mirror, a lens, a prism, a collimator, a polarizer, a beam splitter, and a mask in addition to a laser light source, whereby laser irradiation is performed. The device for grinding and repairing the surface of a silicon wafer according to any one of claims 1 or 2, wherein the conditions can be changed. A pair of lasers split by a beam splitter are incident on individual galvanometer mirrors, further reflected, and each reflected laser irradiates a pair of outer peripheral arc portions of a notch portion of the silicon wafer, and / Alternatively, the apparatus for grinding and repairing the surface of a silicon wafer according to any one of claims 1 to 3, wherein the chamfered slope on the front side and the chamfered slope on the back side of the silicon wafer are respectively irradiated. .. It is a method of grinding the surface of a silicon wafer and repairing the surface after grinding.
A step of attaching the silicon wafer to a wafer feed unit that holds the silicon wafer so that at least one of rotation, movement, and tilting can be performed.
The process of grinding the surface of the silicon wafer held by the wafer feed unit with the grinding unit, and
The surface of the ground silicon wafer is provided with a step of irradiating the surface of the ground silicon wafer with a laser using a laser irradiation repair device.
In the use of the laser irradiation repair device
Prior to laser irradiation, a step of measuring the surface state and / or shape of the silicon wafer held in the wafer feed unit by a measuring device provided in the laser irradiation repair device, and
A step of setting the laser irradiation condition and / or the irradiation atmosphere based on the measurement data by the measuring device by the control device provided in the laser irradiation repair device.
A step of irradiating the ground surface of the silicon wafer with a laser by a laser irradiation unit provided in the laser irradiation repair device according to the setting conditions of the control device.
A step of measuring the surface condition of the silicon wafer during and / or after the laser irradiation by the measuring device and confirming whether or not the surface of the silicon wafer has been repaired.
If it is repaired, the laser irradiation is terminated, and if it is not repaired, the laser irradiation is restarted or continued until the repair is confirmed.
A method for grinding and repairing the surface of a silicon wafer, which comprises. In the step of irradiating the ground surface of the silicon wafer with a laser by the laser irradiation unit provided in the laser irradiation repair device, the outer peripheral edge portion and / or the notch portion chamfered by the grinding of the silicon wafer is lasered. The method for grinding and repairing the surface of a silicon wafer according to claim 5, wherein the silicon wafer is irradiated. A pair of lasers split by a beam splitter are incident on individual galvanometer mirrors, further reflected, and each reflected laser irradiates a pair of outer peripheral arc portions of a notch portion of the silicon wafer, and / The method for grinding and repairing the surface of a silicon wafer according to claim 5 or 6, wherein the chamfered slope on the front side and the chamfered slope on the back side of the silicon wafer are respectively irradiated.