JP7046573B2 - Processing method of work piece - Google Patents

Description

The present invention relates to a method for processing a plate-shaped workpiece to be ground and then polished.

Generally, various wafers (workpieces) such as semiconductor wafers made of silicon on which a semiconductor device is formed on the front surface, sapphire on which an optical device is formed, and optical device wafers made of SiC (silicon carbide), etc., have a back surface side. After being ground and thinned with a grinding wheel, the back surface is polished. As a grinding and polishing device for processing this type of wafer, a plurality of holding tables for holding each wafer, a turntable in which a plurality of holding tables are arranged, and a turntable that rotates to be above one holding table. It has a grinding means for rough grinding, a grinding means for finish grinding, and a polishing means, which are sequentially positioned in the above, and it is known that one wafer is continuously processed in the order of rough grinding, finish grinding, and polishing. (See, for example, Patent Document 1). In this type of grinding and polishing apparatus, each holding table includes a holding surface for holding the wafer rotatably, and an inclination adjusting unit for adjusting the inclination of the rotation axis passing through the center of the holding surface.

Japanese Unexamined Patent Publication No. 2006-344878

In the conventional grinding and polishing apparatus, the shape of the wafer after the finish grinding process is measured, and the inclination of the holding surface of one holding table is feedback-controlled based on the measurement result. By this feedback control, the wafer held on the next holding table was continuously machined so as to be flat after the finish grinding.

However, even if the wafer is flattened during the finish grinding process, the polishing rate during the polishing process may become non-uniform as the number of processed sheets increases, and the shape of the surface to be polished of the wafer after the polishing process. There was a problem that the wafer was not flat. For example, as the number of processed wafers increases, heat gradually accumulates in the center of the polishing pad of the polishing means, so that the amount of the center of the wafer removed during the polishing process tends to increase. For this reason, the wafer after the polishing process has a problem that the thickness of the wafer to be polished is not flat due to the thickness variation of the reference value or more.

The present invention has been made in view of the above, and when the polishing process is performed after the grinding process, the workpiece that can suppress the variation in the thickness of the workpiece after the polishing process and flatten the shape of the surface to be polished. The purpose is to provide a processing method for .

In order to solve the above-mentioned problems and achieve the object, the present invention has a holding surface that rotatably holds the workpiece, and the holding table configured so that the inclination of the rotation axis of the holding surface can be adjusted. A rotating means for grinding the workpiece held on the holding surface of the holding table, a polishing means for polishing the workpiece ground by the grinding means, and a plurality of holding tables. A method for processing a work piece by a grinding device including at least a possible turntable, wherein the work piece held on the holding surface of one holding table is processed by the grinding means. A grinding step that thins to a predetermined thickness, and after performing the grinding step, the turntable is rotated to position one holding table under the polishing means, and the workpiece is polished by the polishing means. From the results of the polishing step to be performed, the thickness measuring step for measuring the thickness variation of the workpiece after the polishing step, and the thickness variation measured in the thickness measuring step, the holding table is next to one. The tilt correction step for correcting the tilt of the rotating shaft in the grinding step and the thickness variation measured in the thickness measuring step so that the shape of the held workpiece after the polishing step becomes flat. A determination step for determining whether or not it is larger than a predetermined reference value is provided, and when it is determined in the determination step that the thickness variation is larger than the reference value, the inclination correction step is performed and the determination is made. When it is determined in the step that the thickness variation is equal to or less than the reference value, the frequency of performing the thickness measurement step is changed according to the value of the thickness variation .

According to this configuration, in order to correct the inclination of the rotation axis of the holding table during grinding by the thickness variation of the workpiece measured after the polishing step, the thickness variation of the workpiece after polishing is equal to or less than the standard value. Can be suppressed to. Therefore, even if the number of processed sheets increases, the surface to be processed after polishing can be kept in a flat shape. Here, flat means that the measured thickness variation of the workpiece, that is, the difference between the maximum measured value and the minimum assumed value of the thickness of the workpiece is equal to or less than a predetermined reference value.

According to this configuration, when the thickness variation of the workpiece is equal to or less than the reference value, that is, when the workpiece is flat, the frequency of measuring the thickness variation is changed, so that the machining accuracy of the workpiece is maintained. At the same time, the machining time can be shortened and the workability can be improved.

According to the present invention, in order to correct the inclination of the rotation axis of the holding table during grinding due to the thickness variation of the workpiece measured after polishing, the thickness variation of the workpiece after polishing is equal to or less than the reference value. Can be suppressed to. Therefore, even if the number of processed sheets increases, the surface to be processed after polishing can be kept in a flat shape.

FIG. 1 is a perspective view of a wafer, which is a processing target of the processing method of the workpiece according to the present embodiment. FIG. 2 is a perspective view of a configuration example of the grinding and polishing apparatus according to the present embodiment. FIG. 3 is a perspective view of a configuration example of a polishing unit of the grinding and polishing apparatus shown in FIG. FIG. 4 is a plan view of a configuration example of the thickness measuring unit of the grinding and polishing apparatus shown in FIG. FIG. 5 is a side view showing a holding table and an inclination adjusting mechanism of the grinding and polishing apparatus shown in FIG. FIG. 6 is a schematic view showing a state in which the holding table is tilted with respect to the finish polishing unit. FIG. 7 is a plan view showing an arrangement example of the position adjusting unit constituting the tilt adjusting mechanism shown in FIG. FIG. 8 is a flowchart showing a procedure of a method of processing a wafer, which is a workpiece according to the present embodiment. FIG. 9 is a schematic cross-sectional view of a wafer having a concave cross-sectional shape. FIG. 10 is a schematic view showing a state in which the holding table is tilted so that the shape of the wafer after finish grinding is a hollow shape. FIG. 11 is a schematic cross-sectional view of a wafer having a medium-convex cross-sectional shape. FIG. 12 is a schematic view showing a state in which the holding table is tilted so that the shape of the wafer after finish grinding is a mid-convex shape.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

This embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer, which is a processing target of the processing method of the workpiece according to the present embodiment. FIG. 2 is a perspective view of a configuration example of the grinding and polishing apparatus according to the present embodiment. FIG. 3 is a perspective view of a configuration example of a polishing unit of the grinding and polishing apparatus shown in FIG. FIG. 4 is a plan view of a configuration example of the thickness measuring unit of the grinding and polishing apparatus shown in FIG. FIG. 5 is a side view showing a holding table and an inclination adjusting mechanism of the grinding and polishing apparatus shown in FIG. FIG. 6 is a schematic view showing a state in which the holding table is tilted with respect to the finish polishing unit. FIG. 7 is a plan view showing an arrangement example of the position adjusting unit constituting the tilt adjusting mechanism shown in FIG.

The processing method of the workpiece according to the present embodiment is a processing method of grinding and polishing the back surface 201 of the wafer (workpiece) 200 shown in FIG. 1, and the wafer 200 is thinned to a predetermined finish thickness. The method. The wafer 200 is, for example, a disk-shaped semiconductor wafer or sapphire whose base material is silicon, an optical device wafer whose base material is SiC (silicon carbide), or the like. As shown in FIG. 1, in the wafer 200, the device 204 is formed in a plurality of regions partitioned by the grid-shaped scheduled division lines 203 formed on the surface 202. As shown in FIG. 2, the wafer 200 has a protective member 205 attached to the front surface 202, and the back surface 201 is ground by the grinding / polishing device 1 to be thinned to a predetermined thickness. The back surface 201 is polished. The protective member 205 is formed of a disk shape having the same size as the wafer 200, and is made of a flexible synthetic resin.

As shown in FIG. 2, the grinding and polishing apparatus 1 includes an apparatus main body 2, a rough grinding unit (grinding means) 3, a finish grinding unit (grinding means) 4, a polishing unit (polishing means) 5, and a turntable 8. For example, four holding tables 9 (9a to 9d) installed above, a thickness measuring unit 10, cassettes 11 and 12, a position table 13, a transfer arm 15, a robot pick 16, and a spinner cleaning device 17. , A control device (control unit) 100 is mainly provided. The grinding and polishing device 1 is a fully automatic type processing device, and under the control of the control device 100, the wafer 200 is subjected to a series of rough grinding, finish grinding, polishing, cleaning, and loading / unloading processing. It is configured to carry out the work of.

The rough grinding unit 3 includes a disk-shaped wheel mount 3b mounted on the lower end of the spindle 3a, and a rough grinding wheel 3c mounted on the lower surface of the wheel mount 3b. The rough grinding wheel 3c has a large number of grinding wheels for rough grinding (not shown), and these grinding wheels are arranged in an annular shape and fixed to the lower surface of the wheel mount 3b. Further, the rough grinding unit 3 is arranged so as to be movable up and down with respect to the holding table 9. The rough grinding unit 3 roughly grinds the back surface 201 of the wafer 200 by pressing the grinding wheel against the back surface 201 of the wafer 200 held on the holding table 9 while rotating the rough grinding wheel 3c via the spindle 3a. Process.

Like the rough grinding unit 3, the finish grinding unit 4 includes a disk-shaped wheel mount 4b mounted on the lower end of the spindle 4a and a finish grinding wheel 4c mounted on the lower surface of the wheel mount 4b. The finish grinding wheel 4c has a large number of grinding wheels 4d (FIG. 6) for finish grinding, and these grinding wheels 4d are arranged in an annular shape and fixed to the lower surface of the wheel mount 4b. The grinding wheel 4d for finish grinding is formed by solidifying abrasive grains having a finer particle size with a binder as compared with the grinding wheel for rough grinding. Like the rough grinding unit 3, the finish grinding unit 4 is arranged so as to be movable up and down with respect to the holding table 9. The finish grinding unit 4 presses the grinding wheel 4d against the back surface 201 of the wafer 200 held by the holding table 9 while rotating the finish grinding wheel 4c around the rotating shaft 43 (FIG. 6) via the spindle 4a. The back surface 201 of the wafer 200 is finish-ground.

As shown in FIG. 3, the polishing unit 5 includes a polishing pad 5c mounted on the lower end of the spindle 5a via a polishing mount 5b. The polishing pad 5c polishes the back surface 201 of the wafer 200 by pressing it against the back surface 201 of the wafer 200 after the finish grinding process held on the holding table 9 (FIG. 2) while rotating together with the spindle 5a. The polishing pad 5c is deformed according to the shape of the wafer 200 to be polished, and the lower surface of the polishing pad 5c comes into contact with the back surface 201 of the wafer 200 to become the polishing surface of the back surface 201. The polishing unit 5 includes a moving mechanism 6 for moving the polishing unit 5. The moving mechanism 6 moves the polishing unit 5 in the horizontal direction (the radial direction of the polishing pad 5c, the X-axis direction in FIGS. 2 and 3) and the vertical direction (the axial direction of the spindle 5a, the Z-axis direction in FIGS. 2 and 3). be able to. Further, although not shown, the polishing unit 5 is connected to a processing liquid supply unit that selectively supplies the polishing liquid or the cleaning liquid to the back surface 201 of the wafer 200 at the time of polishing processing.

As shown in FIG. 2, the turntable 8 is a disk-shaped table provided on the upper surface of the apparatus main body 2, is rotatably provided in the horizontal direction (arrow R direction in the figure), and is rotationally driven at a predetermined timing. Will be done. On the turntable 8, for example, four holding tables 9 (9a to 9d) are arranged at equal intervals with a phase angle of, for example, 90 degrees. Further, on the turntable 8, for example, a thickness measuring unit 10 for measuring the thickness of the wafer 200 after polishing is provided. The thickness measuring unit 10 includes a support column 10c erected on the turntable 8, an arm 10b extending horizontally from the upper end portion of the support column 10c, and a measurement head 10a fixed to the tip of the arm 10b. The measuring head 10a radiates ultrasonic waves toward the back surface 201 of the wafer 200, for example, and measures the height position of the back surface 201 of the wafer 200 from the reflection time. In this case, since the distance from the measuring head 10a to the holding table 9 is measured and known in advance, the thickness of the wafer 200 can be measured from the difference value from the measured height position. Further, in the present embodiment, the thickness measuring unit 10 has an arc shape (arrow RA) in a radial region on one side from the center 200A of the wafer 200 to the outer peripheral portion 200B so that the measuring head 10a passes through the center of the wafer 200. It is moved, the thickness of the movement locus at a plurality of points (for example, 3 points) is measured, and the thickness is transmitted to the control device 100. Based on the received measured value, the control device 100 considers the radial region on the opposite side of the wafer 200 to be a symmetrical shape and calculates the entire cross-sectional shape.

As shown in FIG. 5, the holding table 9 has a holding surface 91 that holds the surface 202 side of the weight 200 via the protective member 205, and a rotation axis that passes through the center of the holding surface 91 and is shown by a dotted line in FIG. A 92 and an inclination adjusting mechanism (inclination adjusting means) 40 for inclining the rotating shaft 92 with respect to the vertical direction are provided. The holding table 9 has a structure in which a vacuum chuck is provided on the holding surface 91, and holds the wafer 200 placed on the holding surface 91 by vacuum suction.

As shown in detail in FIG. 6, the holding surface 91 is formed in a conical shape in which the outer peripheral portion 91B is slightly lower than the center 91A. That is, the holding surface 91 is formed on a conical surface having the center 91A as an apex, and is formed on a slope having an inclination descending from the center 91A toward the outer peripheral portion 91B. The holding table 9 holds the wafer 200 to be processed following the conical surface of the holding surface 91. Although FIG. 6 exaggerates the inclination of the conical surface of the holding surface 91, the inclination of the conical surface of the holding surface 91 is a slight inclination that cannot be actually recognized by the naked eye.

The tilt adjusting mechanism 40 is attached to each holding table 9. As shown in FIG. 5, the inclination adjusting mechanism 40 is for changing (adjusting) the inclination θ (FIG. 6) of the rotating shaft 92 with respect to the vertical direction (Z direction). As shown in FIG. 5, the tilt adjusting mechanism 40 includes a support base 22 and a position adjusting unit 23 connected to the support base 22. The support base 22 includes a support cylinder portion 220 formed in a cylindrical shape that rotatably supports the holding table 9 via a bearing (not shown), and a flange portion 221 whose diameter is expanded from the support cylinder portion 220. The tilt adjusting mechanism 40 adjusts the tilt θ of the rotating shaft 92 by adjusting the tilt of the flange portion 221.

As shown in FIG. 7, two or more position adjusting units 23 are provided at equal intervals along the arc of the flange portion 221. In the present embodiment, the tilt adjusting mechanism 40 arranges two position adjusting units 23 and a fixing portion 23a for fixing the flange portion 221 at intervals of 120 degrees, but in the present invention, the position adjusting unit 23 is set to 3. You may arrange more than one.

As shown in FIG. 5, the position adjusting unit 23 includes a cylinder portion 230 fixed to the turntable 8, a shaft 231 penetrating the cylinder portion 230, a drive unit 232 connected to the lower end of the shaft 231 and a shaft 231. It is provided with a fixing portion 233 fixed to the flange portion 221 at the upper end of the. The drive unit 232 includes a motor 232a that rotates the shaft 231 and a speed reducer 232b that reduces the rotation speed of the shaft 231 and is fixed to the turntable 8.

The fixing portion 233 is provided with a female screw (not shown) into which a male screw (not shown) formed at the upper end of the shaft 231 is screwed. The position adjusting unit 23 adjusts the inclination θ of the rotating shaft 92 by the motor 232a rotating the shaft 231 around the axis center via the speed reducer 232b. Further, a motor 24 that rotates the holding table 9 about the rotation shaft 92 is attached to the turntable 8.

The holding table 9 is rotationally driven by a motor 24 around a rotating shaft 92 during grinding and polishing. As shown in FIG. 2, the holding tables 9a to 9d move around in the order of the carry-in / carry-out area A, the rough grinding area B, the finish grinding area C, and the polishing area D by the rotation of the turntable 8. ..

As shown in FIG. 2, the cassettes 11 and 12 are containers for a wafer 200 having a plurality of slots. One cassette 11 accommodates the wafer 200 before grinding and polishing, and the other cassette 12 accommodates the wafer 200 after polishing. The position table 13 is a table on which the wafer 200 taken out from the cassette 11 is temporarily placed and the center of the wafer 200 is aligned.

The transport arm 15 is configured to be movable in the horizontal direction (Y-axis direction), transports the wafer 200 before grinding and polishing placed on the position table 13, and is located in the carry-in / carry-out area A. Place on. Further, the transport arm 15 transports the polished wafer 200 placed on the holding table 9a located in the carry-in / carry-out area A again and places it on the spinner table of the spinner cleaning device 17.

The robot pick 16 includes a wafer holding portion (for example, a U-shaped hand) 16A, and the wafer holding portion 16A sucks and holds the wafer 200 and conveys it. Specifically, the robot pick 16 conveys the wafer 200 before grinding and polishing from the cassette 11 to the position table 13. Further, the polished wafer 200 is conveyed from the spinner cleaning device 17 to the cassette 12. The spinner cleaning device 17 cleans the polished wafer 200 to remove contamination such as grinding debris and polishing debris adhering to the ground and polished machined surface.

The control device 100 controls each of the above-mentioned components constituting the grinding and polishing device 1. That is, the control device 100 causes the grinding and polishing device 1 to perform a grinding and polishing operation on the wafer 200. The control device 100 is a computer capable of executing a computer program. The control device 100 has an arithmetic processing unit 101 having a microprocessor such as a CPU (central processing unit), a storage unit 102 having a memory such as a ROM (read only memory) or a RAM (random access memory), and input / output. It has an interface device. The arithmetic processing unit 101 executes a computer program stored in the ROM on the RAM to generate a control signal for controlling the grinding and polishing device 1, and the generated control signal is passed through the input / output interface device. It is output to each component of the grinding device 1.

Further, the storage unit 102 of the present embodiment stores the thickness data of the wafer 200 measured by the thickness measuring unit 10 after the polishing process, the thickness variation based on the thickness data, and the data regarding the shape of the wafer 200. ing. Further, the storage unit 102 stores a correction value of the inclination θ of the rotation axis 92 of the holding table 9 calculated by the arithmetic processing unit 101 based on the result of the thickness variation. This thickness variation is the difference between the maximum value and the minimum value of the thickness of the wafer 200, and the data regarding the shape of the wafer 200 is that the shape of the wafer 200 after polishing is (1) the center 200A is the thinnest and the outer peripheral portion 200B. It is data about a middle-concave shape that gradually becomes thicker toward the center, and (2) a middle-convex shape that is thickest at the center 200A and gradually becomes thinner toward the outer peripheral portion 200B. For example, as the number of processed wafers increases, heat gradually accumulates in the center of the polishing pad 5c of the polishing unit 5, so that the amount of heat removed from the center of the wafer 200 during the polishing process increases, and the shape tends to be hollow. It is in. Further, for example, when the rotation speed of the spindle 5a of the polishing unit 5 is high, the impact of contact between the polishing pad 5c and the outer peripheral portion 200B of the wafer 200 becomes large, so that the amount of removal of the outer peripheral portion 200B of the wafer 200 is large during the polishing process. Therefore, it tends to have a medium-convex shape.

Further, the correction value is based on the shape of the wafer 200 after being held and polished by one holding table 9a in the previous round, and finish grinding so that the wafer 200 becomes flat after polishing in the next round. This is a correction value for setting the inclination θ of the rotation axis 92 of one holding table 9a with respect to the unit 4. For example, when the shape of the wafer 200 after polishing is a hollow shape in the previous round, in the next round, the inclination θ of the rotary shaft 92 of one holding table 9a with respect to the finish grinding unit 4 is after finish grinding. The shape of the wafer 200 is corrected to the inclination θ which is a middle-convex shape obtained by reversing the above-mentioned middle-concave shape to an inverted shape. As a result, the wafer 200 having a medium-convex shape is polished as it is, and the wafer 200 after polishing becomes flat. Here, flat means that the measured thickness variation of the wafer 200, that is, the difference between the maximum value and the minimum value of the thickness of the wafer 200 is equal to or less than a predetermined reference value.

Further, in the configuration in which a plurality of (4) holding tables 9 (9a to 9d) rotate together with the turntable 8 as in the present embodiment, individual differences in the holding tables 9a to 9d occur. The thickness data of the wafer 200, the data regarding the thickness variation and the shape of the wafer 200, and the correction value of the inclination θ of the rotating shaft 92 are stored in each of the holding tables 9a to 9d.

Next, a processing method of the wafer 200 as a workpiece will be described. FIG. 8 is a flowchart showing a procedure of a processing method for a workpiece according to the present embodiment. First, the wafer 200 is held on the holding surface 91 of the holding table 9 (step S1; holding step). In the wafer 200, the protective member 205 is attached to the front surface 202 side, the back surface 201 side faces upward, and the holding table 9a (one of the four holding tables 9) is used in the carry-in / carry-out area A of the turntable 8. It is held on the holding surface 91 of the holding table).

Next, rough grinding is executed on the wafer 200 held on the holding table 9a (step S2; rough grinding step). The wafer 200 held by the holding table 9a moves to the rough grinding region B by rotating the turntable 8 by 90 degrees. In this rough grinding region B, with the holding table 9a rotated, the rough grinding wheel 3c of the rough grinding unit 3 is rotated and lowered, and the grinding wheel of the rotating rough grinding wheel 3c comes into contact with the back surface 201 of the wafer 200. Rough grinding is performed to reduce the thickness to near the predetermined thickness. In this rough grinding step, the arithmetic processing unit 101 of the control device 100 sets the inclination θ of the rotation shaft 92 of the holding table 9a as the reference set value. This reference setting value is set at an angle at which the surface to be ground (back surface 201) of the weight 200 and the grinding surface (bottom surface) of the grinding wheel of the rough grinding wheel 3c of the rough grinding unit 3 are parallel to each other after the rough grinding step is executed. It is set.

When the rough grinding step is completed, the arithmetic processing unit 101 determines whether or not a correction value is set for the inclination θ of the rotation axis 92 of the holding table 9a (step S3). If the correction value is not set (step S3; No), the inclination correction step (step S4) is skipped and the process proceeds to step S5. The tilt correction step will be described later.

Next, finish grinding is executed on the wafer 200 held on the holding table 9a (step S5; finish grinding step). This finish grinding step corresponds to the grinding step in the present invention. The finish grinding step may include the above-mentioned rough grinding step as a grinding step. After the rough grinding step is completed, the turntable 8 is further rotated by 90 degrees, so that the holding table 9a holding the coarsely ground wafer 200 is moved to the finish grinding area C. In this finish grinding region C, with the holding table 9a rotated, the finish grinding wheel 4c of the finish grinding unit 4 is rotated and lowered, and the rotating grindstone 4d of the finish grinding wheel 4c is placed on the back surface 201 of the waha 200. Perform finish grinding to make contact and thin to a predetermined thickness. In this finish grinding step, the arithmetic processing unit 101 sets the inclination θ of the rotation shaft 92 of the holding table 9a to the latest set value (first inclination). That is, if the correction value has been set before, the correction value is read from the storage unit 102 and set, and if the correction value has never been set, it is set to the above-mentioned reference setting value. The grinding wheel 4d of the finish grinding wheel 4c always comes into contact with the center 200A (rotation center) of the back surface 201 of the weight 200, regardless of the setting value of the inclination θ of the rotation shaft 92 of the holding table 9a. There is.

Next, the finish-ground wafer 200 held on the holding table 9a is polished (step S6; polishing step). The holding table 9a holding the finish-ground wafer 200 is moved to the polishing region D and positioned under the polishing unit 5 by further rotating the turntable 8 by 90 degrees. In this case, the inclination θ of the rotating shaft 92 of the holding table 9a is the inclination set in the finish grinding step. In the polishing region D, while the holding table 9a is rotated, the polishing pad 5c of the polishing unit 5 is rotated and lowered, and the rotating polishing pad 5c is brought into contact with the back surface 201 of the wafer 200 to perform polishing. Since the machining fluid is supplied from the machining fluid supply unit (not shown) during polishing, the back surface 201 of the wafer 200 can be chemically mechanically polished (CMP polishing) by the polishing pad 5c and the machining fluid. It is also possible to perform dry polishing without using a processing liquid.

Next, the arithmetic processing unit 101 measures the thickness variation of the wafer 200 after polishing (step S7; thickness measurement step). In this thickness measurement step, the arithmetic processing unit 101 controls the operation of the thickness measurement unit 10 to measure the height position of the surface to be polished (back surface 201) at a plurality of points, and the height of the holding surface 91 of the holding table 9a. The thickness and thickness variation of the wafer 200 at a plurality of points are measured (calculated) from the difference value from the position. Specifically, as shown in FIG. 4, the measurement head 10a of the thickness measuring unit 10 passes through the center of the wafer 200 and has an arc shape in a radial region on one side from the center 200A of the wafer 200 to the outer peripheral portion 200B. It is moved to the arrow RA), the thickness at a plurality of points (for example, 3 points) of the movement locus is measured, and the thickness variation is measured (calculated) from this thickness. At this time, along with the variation in thickness, it is determined whether the cross-sectional shape of the wafer 200 is a middle concave shape or a middle convex shape. The thickness data of the wafer 200, the thickness variation, and the data regarding the shape of the wafer 200 are associated with the holding table 9a and stored in the storage unit 102 of the control device 100.

Next, the arithmetic processing unit 101 determines whether or not the thickness variation is larger than a predetermined reference value (step S8; determination step). In this determination, when the thickness variation is larger than the reference value (for example, 5 μm) (step S8; Yes), the arithmetic processing unit 101 sets a correction value for the inclination θ of the rotation axis 92 of the holding table 9a (step). S9; correction value setting step).

Specifically, in the previous round, the thickness variation is larger than the reference value, and the shape of the wafer 200 after polishing is the thinnest at the center 200A and gradually toward the outer peripheral portion 200B as shown in FIG. In the case of a middle-concave shape having a thicker thickness, the arithmetic processing unit 101 makes the shape of the wafer 200 after finish grinding a middle-convex shape obtained by reversing the above-mentioned middle-concave shape in the next round. A correction value for correcting the inclination θ of the rotation axis 92 of the holding table 9a with respect to the finish grinding unit 4 is set. For example, a tilt correction value is set so that the two position adjusting units 23 of the tilt adjusting mechanism 40 are evenly lowered by several μm with respect to the fixed portion 23a so that the thickness variation is within the reference value. When the correction value is set in step S3 described above (step S3; Yes), the inclination correction step (step S4) of the wafer 200 to be finish-ground in the next round is executed. In this tilt correction step, the tilt θ of the rotation shaft 92 of the holding table 9a is corrected to the above-mentioned correction value, so that the shape of the wafer 200 after finish grinding is formed into a medium-convex shape as shown in FIG. be able to. By correcting the shape after finish grinding to the inclination θ that makes the shape medium-convex, the wafer 200 having the medium-convex shape is polished as it is, and the wafer 200 after polishing becomes flat.

Further, in the previous lap, the thickness variation is larger than the reference value, and the shape of the wafer 200 after polishing is the thickest at the center 200A and gradually becomes thinner toward the outer peripheral portion 200B as shown in FIG. In the case of a medium-convex shape, the arithmetic processing unit 101 performs finish grinding so that the shape of the wafer 200 after finish grinding becomes a medium-concave shape obtained by reversing the above-mentioned medium-convex shape to an inverted shape in the next round. A correction value for correcting the inclination θ of the rotation axis 92 of one holding table 9a with respect to the unit 4 is set. For example, a tilt correction value is set so that the two position adjusting units 23 of the tilt adjusting mechanism 40 are evenly raised by several μm with respect to the fixed portion 23a so that the thickness variation is within the reference value. When the correction value is set in step S3 described above (step S3; Yes), the inclination correction step (step S4) of the wafer 200 to be finish-ground in the next round is executed. In this tilt correction step, the tilt θ of the rotating shaft 92 of one holding table 9a is corrected to the above-mentioned correction value, so that the shape of the wafer 200 after finish grinding is formed into a concave shape as shown in FIG. be able to. By correcting the shape after finish grinding to the inclination θ that makes the shape hollow, the wafer 200 having the hollow shape is polished as it is, and the wafer 200 after polishing becomes flat.

On the other hand, when the thickness variation is equal to or less than the reference value (step S8; No), the arithmetic processing unit 101 changes the frequency of performing the above-mentioned thickness measurement step (step S10; measurement frequency changing step). When the inclination θ of the rotation shaft 92 of the holding table 9a is corrected, the shape of the wafer 200 after polishing changes as described above. Therefore, it is necessary to carry out the thickness measurement step immediately after the correction. On the other hand, unless the processing conditions are changed, the shape of the wafer 200 does not suddenly change significantly. Therefore, if the thickness variation of the wafer 200 after polishing is equal to or less than the reference value, that is, if the wafer is processed flat, the frequency of performing the thickness measurement step is reduced (the measurement interval is lengthened). Specifically, a frequency change reference value smaller than the above-mentioned thickness variation reference value is set in advance. When the measured thickness variation is larger than the frequency change reference value, the arithmetic processing unit 101 determines the frequency of performing the thickness measurement step every 10 laps (held by one holding table 9a and ground and polished). 200 is every 10 sheets), and when the measured thickness variation is larger than the frequency change reference value, the frequency of performing the thickness measurement step is, for example, every 30 laps. According to this configuration, while maintaining the processing accuracy of the wafer 200, the processing time for grinding and polishing can be shortened, and the processability can be improved.

In the above-mentioned processing procedure, a configuration for correcting the inclination θ of the rotation axis 92 of one holding table 9a based on the shape of the wafer 200 after polishing has been described, but a plurality of (four) holding tables 9a to 9d are used. In the configuration of rotating on the turntable 8, the inclination of the rotation shaft 92 is independently corrected for each of the holding tables 9a to 9d.

As described above, the present embodiment has a holding surface 91 that rotatably holds the weight 200, and a holding table 9 configured so that the inclination of the rotation shaft 92 of the holding surface 91 can be adjusted, and a holding surface of the holding table 9. A finish grinding unit 4 for grinding the waha 200 held in the 91, a polishing unit 5 for polishing the waha 200 ground by the finish grinding means, and a rotatable turntable 8 in which a plurality of holding tables 9 are arranged are provided. It is a processing method of the waha 200 that processes the waha 200 by at least the grinding and polishing device 1 provided, and the waha 200 held on the holding surface 91 of one holding table 9a is thinned to a predetermined thickness by the finish grinding unit 4. After performing the finish grinding step S5 and the finish grinding step S5, the turntable 8 is rotated to position one holding table 9a under the polishing unit 5, and the polishing step S6 for polishing the wafer 200 by the polishing unit 5. After the polishing step S6 is performed, the waha 200 is held on one holding table 9a in the next round based on the results of the thickness measurement step S7 for measuring the thickness variation of the waha 200 and the thickness variation measured in the thickness measurement step S7. A tilt correction step S4 for correcting the tilt of the rotating shaft 92 in the finish grinding step S5 is provided so that the shape after the polishing step S6 is flattened.

According to this configuration, the thickness of the wafer 200 after the polishing step S6 is corrected in order to correct the inclination of the rotating shaft 92 of the holding table 9a at the time of performing the finish grinding step S5 due to the thickness variation of the wafer 200 measured after the polishing step S6. The variation can be suppressed below the standard value. Therefore, for example, even if the number of processed wafers increases, the surface to be processed of the wafer 200 after polishing can be kept in a flat shape.

Further, according to the present embodiment, a determination step S8 for determining whether or not the thickness variation measured in the thickness measurement step S7 is larger than a predetermined reference value is provided, and the thickness variation is larger than the reference value in the determination step S8. If it is determined to be large, the correction value setting step S9 and the tilt correction step S4 are performed, and if the thickness variation is determined to be equal to or less than the reference value in the determination step S8, the thickness measurement step S7 is performed according to the thickness variation value. Since the measurement frequency change step S10 for changing the frequency to be performed is provided, the machining time can be shortened and the workability can be improved while maintaining the machining accuracy of the weight 200.

Further, the grinding and polishing apparatus 1 according to the present embodiment has a holding table 9 having a holding surface 91 for rotatably holding the wafer 200 and an inclination adjusting mechanism 40 for adjusting the inclination of the rotation shaft 92 of the holding surface 91, and holding. A rotatable finish grinding unit 4 for finish-grinding the wafer 200 held on the holding surface 91 of the table 9, a polishing unit 5 for polishing the wafer 200 ground by the finish-grinding unit 4, and a plurality of holding tables 9 are arranged. The thickness measuring unit 10 for measuring the thickness variation of the polished wafer 200 held on the holding surface 91 of one holding table 9a of the turntable 8 and the plurality of holding tables 9, and the thickness measured by the thickness measuring unit 10. From the result of the variation, the tilt adjusting mechanism 40 is driven so as to flatten the polished shape of the wafer 200 held in one holding table 9a in the next round, and is located under the finish grinding unit 4. A control device 100 for correcting the inclination θ of the rotation axis 92 of the holding table 9a is provided. According to this configuration, the control device 100 corrects the inclination θ of the rotating shaft 92 of the holding table 9a during the finish grinding process due to the thickness variation of the wafer 200 measured after the polishing process, so that the wafer 200 after the polishing process is corrected. It is possible to suppress the thickness variation of the above to the standard value or less. Therefore, even if the number of processed sheets increases, the surface to be processed (back surface 201) of the wafer 200 after polishing can be kept in a flat shape.

The present invention is not limited to the above embodiment. That is, it can be variously modified and carried out within a range that does not deviate from the gist of the present invention.

1 Grinding and polishing equipment 2 Equipment body 3 Rough grinding unit 4 Finish grinding unit (grinding means)
5 Polishing unit (polishing means)
8 Turntable 9, 9a, 9b, 9c, 9d Holding table 10 Thickness measuring unit 23 Position adjustment unit 23a Fixed unit 24 Motor 40 Tilt adjustment mechanism (tilt adjustment means)
91 Holding surface 92 Rotating shaft 100 Control device (control unit)
101 Arithmetic processing unit 102 Storage unit 200 Wafer 201 Back side 202 Front side 205 Protective member

Claims (1)

A holding table that has a holding surface that rotatably holds the workpiece and is configured so that the inclination of the rotation axis of the holding surface can be adjusted.
A grinding means for grinding the workpiece held on the holding surface of the holding table, and
A polishing means for polishing the workpiece ground by the grinding means, and
A method for processing a work piece, wherein the work piece is machined by a grinding and polishing apparatus including at least a rotatable turntable in which a plurality of holding tables are arranged.
A grinding step in which a workpiece held on the holding surface of one holding table is thinned to a predetermined thickness by the grinding means, and a grinding step.
After performing the grinding step, a polishing step in which the turntable is rotated to position one holding table under the polishing means and the workpiece is polished by the polishing means.
After performing the polishing step, a thickness measuring step for measuring the thickness variation of the workpiece and a thickness measuring step
From the result of the thickness variation measured in the thickness measuring step, the rotation in the grinding step so that the shape of the workpiece next to be held in the holding table after the polishing step becomes flat. A tilt correction step that corrects the tilt of the axis, and
A determination step for determining whether or not the thickness variation measured in the thickness measurement step is larger than a predetermined reference value is provided.
If it is determined in the determination step that the thickness variation is larger than the reference value, the inclination correction step is performed.
When the thickness variation is determined to be equal to or less than the reference value in the determination step, the method for processing the workpiece is characterized in that the frequency of performing the thickness measurement step is changed according to the value of the thickness variation. ..

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