JP2019022920A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method that can suppress dispersion between a polishing rate when processing the first wafer after idling operation and a polishing rate during continuous processing of wafers.SOLUTION: The wafer processing method comprises at least: an idling step ST1 of driving a polishing unit of a grinding/polishing device; and a grinding/polishing step ST2 of polishing with a polishing pad wafers held on a chuck table of the grinding/polishing device after executing the idling step ST1. As polishing conditions in the grinding/polishing step ST2, two kinds are specified including: an inclination of a rotary shaft during initial processing of polishing a first wafer; and an inclination of the rotary shaft during continuous processing of polishing a second and subsequent wafers. The inclination of the rotary shaft during the initial processing is set so that a polishing rate when polishing the first wafer at the inclination of the rotary shaft during the initial processing becomes identical to a polishing rate thereof when polishing the second and subsequent wafers at the inclination of the rotary shaft during the continuous processing.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a wafer processing method for processing a wafer.

  Various wafers such as a semiconductor wafer made of silicon or the like on which the semiconductor device is formed, or an optical device wafer made of sapphire or SiC (silicon carbide) or the like on which the optical device is formed, are thinned by grinding the back side with a grinding wheel. (See, for example, Patent Document 1), the back surface is polished.

JP 2013-119123 A

  In the polishing apparatus for polishing the back surface of the wafer, the distribution of the removal amount by polishing differs between a wafer that has been continuously processed in full auto and a wafer that has been temporarily stopped and processed after the idling operation. For example, in the polishing device, the removal amount of the central portion (also called the polishing rate) is reduced when the first wafer after the idling operation is processed, compared with the case of continuous processing, and the removal amount of the outer peripheral portion. There is a problem that increases. One reason for this phenomenon seems to be that the heat generated during the processing of the first wafer after idling is less than that during continuous processing.

  An object of the present invention is to provide a wafer processing method capable of suppressing variations between a polishing rate during processing of the first wafer after idling operation and a polishing rate during continuous processing.

  In order to solve the above-described problems and achieve the object, the wafer processing method of the present invention includes a chuck table for holding a wafer, a polishing pad for polishing the wafer held by the chuck table, and the polishing pad. A wafer processing method using a polishing apparatus, comprising: a polishing means including a spindle on which a spindle is mounted; and a motor that rotationally drives the spindle; and a processing feed means for processing and feeding the polishing means, the polishing means A polishing step for polishing the wafer held by the chuck table with the polishing pad after the idling step is performed, and the polishing condition in the polishing step is that of the first wafer. There are two types of processing conditions: initial processing conditions for polishing and continuous processing conditions for polishing the second and subsequent wafers. The initial processing conditions are the same as the polishing rate when the first wafer is polished under the initial processing conditions and the polishing rate when the second and subsequent wafers are polished under the continuous processing conditions. It is set so that it may become.

  In the wafer processing method, the chuck table has a conical holding surface whose outer peripheral portion is slightly lower than the center, a rotation axis passing through the center of the holding surface, and an inclination adjustment for adjusting an inclination of the rotation axis. And the initial machining condition may be set such that the angle of the rotation axis is set so that an angle formed between the polishing pad and the chuck table at a machining point is larger than the continuous machining condition.

  The wafer processing method of the present invention has an effect that it is possible to suppress variation between the polishing rate during processing of the first wafer after idling operation and the polishing rate during continuous processing.

FIG. 1 is a perspective view of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a perspective view of a state in which a protective member is attached to the surface of the wafer shown in FIG. FIG. 3 is a perspective view of a configuration example of a grinding and polishing apparatus used in the wafer processing method according to the first embodiment. 4 is a side view showing a chuck table, a polishing unit and the like of the grinding and polishing apparatus shown in FIG. FIG. 5 is a side view showing an inclination adjusting mechanism of the grinding and polishing apparatus shown in FIG. FIG. 6 is a plan view for explaining measurement points at which the removal amount per unit time of the wafer at the time of initial machining and continuous machining is measured. FIG. 7 is a diagram showing a measurement result of the removal amount per unit time at the time of initial machining of each measurement point shown in FIG. FIG. 8 is a diagram showing a measurement result of the removal amount per unit time at the time of continuous machining of each measurement point shown in FIG. FIG. 9 is a flowchart showing the flow of the wafer processing method according to the first embodiment. FIG. 10 is a sectional side view showing the initial processing of the grinding / polishing step of the wafer processing method shown in FIG. FIG. 11 is a sectional side view showing the continuous processing of the grinding / polishing step of the wafer processing method shown in FIG. FIG. 12 is a diagram for explaining the inclination of the rotation axis during the initial processing of the wafer processing method according to the second embodiment. FIG. 13 is a perspective view of a configuration example of a polishing apparatus used in a wafer processing method according to a modification of the first and second embodiments.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment 1
A wafer processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a perspective view of a state in which a protective member is attached to the surface of the wafer shown in FIG.

  The wafer processing method according to the first embodiment is a processing method for grinding and polishing the back surface 201 of the wafer 200 shown in FIG. 1, and is a method for thinning the wafer 200 to a predetermined finish thickness. A wafer 200 to be processed by the wafer processing method according to the first embodiment is a disk-shaped semiconductor wafer using silicon as a base material, an optical device wafer using sapphire, SiC (silicon carbide), or the like as a base material. As shown in FIG. 1, the wafer 200 has devices 204 formed in a plurality of regions partitioned by lattice-shaped division planned lines 203 formed on the surface 202. As shown in FIG. 2, the wafer 200 is ground on the back surface 201 with the protective member 205 attached to the front surface 202 and thinned to a predetermined thickness, and then polished on the back surface 201. Is done. The protection member 205 is formed in a disk shape having the same size as the wafer 200 and is made of a flexible synthetic resin.

  In the wafer processing method according to the first embodiment, the back surface 201 of the wafer 200 is ground using the grinding / polishing apparatus 1 which is the polishing apparatus shown in FIG. FIG. 3 is a perspective view of a configuration example of a grinding and polishing apparatus used in the wafer processing method according to the first embodiment. 4 is a side view showing a chuck table, a polishing unit and the like of the grinding and polishing apparatus shown in FIG. FIG. 5 is a side view showing an inclination adjusting mechanism of the grinding and polishing apparatus shown in FIG.

  As shown in FIG. 3, the grinding and polishing apparatus 1 includes an apparatus main body 2, a first grinding unit 3, a second grinding unit 4, a polishing unit 5 that is a polishing means, and a work feed that is a work feed means. For example, four chuck tables 7 which are installed on the turntable 6 and hold the wafer 200, cassettes 8 and 9, a positioning unit 10, a loading unit 11, a cleaning unit 13, and a loading / unloading unit 14 and a control device 100 are mainly provided.

  The first grinding unit 3 includes a wafer 200 held on the chuck table 7 at a rough grinding position 102 while a grinding wheel 32 having a grinding wheel mounted on the lower end of a spindle 31 is rotated by a motor 33 while being supplied with grinding water. The back surface 201 of the wafer 200 is roughly ground by being pressed against the back surface 201 along the vertical direction Z. Similarly, the second grinding unit 4 is provided on the chuck table 7 positioned at the finish grinding position 103 while a grinding wheel 42 having a grinding wheel mounted on the lower end of the spindle 41 is rotated by a motor 43 while being supplied with grinding water. The back surface 201 of the wafer 200 is finish-ground by being pressed along the Z-axis direction against the held back surface 201 of the roughly ground wafer 200. In the first embodiment, the axis that is the rotation center of the grinding wheels 32 and 42 of the first grinding unit 3 and the second grinding unit 4 and the rotation shaft 72 of the chuck table 7 shown in FIG. It is arranged at intervals in the direction.

  As shown in FIG. 4, the polishing unit 5 includes a polishing pad 51, a spindle 52, and a motor 53 shown in FIG. The polishing pad 51 is for polishing the wafer 200 held on the chuck table 7. The polishing pad 51 is attached to the lower surface of the disk-shaped support base 55 of the polishing tool 54 and the polishing surface 56 facing the wafer 200 is horizontal. Parallel to the direction. The spindle 52 has a tool mounting member 57 to which a support base 55 of the polishing tool 54 is attached at the lower end, and the polishing pad 51 is attached to the lower end through the support base 55. The motor 53 rotates the spindle 52 to rotate the polishing pad 51 around the axis 58. The processing feed unit 12 is for processing and feeding the polishing unit 5 along the vertical direction Z toward the wafer 200 held by the chuck table 7. The polishing unit 5 moves along the vertical direction Z along the back surface 201 of the finish-ground wafer 200 held by the holding surface 71 of the chuck table 7 located at the polishing position 104 while the polishing tool 54 is rotated. It is pressed by. The polishing unit 5 is for polishing the back surface 201 of the wafer 200 when the polishing pad 51 of the polishing tool 54 is pressed against the back surface 201 of the wafer 200 along the Z-axis direction.

  In the first embodiment, the spindle 52 of the polishing unit 5 and the axis 58 that is the rotation center of the polishing pad 51 are arranged in parallel to the vertical direction Z. The shaft center 58 that is the center of rotation of the spindle 52 and the polishing pad 51 of the polishing unit 5 and the rotation shaft 72 of the chuck table 7 shown in FIG. 4 are arranged at an interval in the horizontal direction. In the first embodiment, the polishing unit 5 is selectively supplied with the polishing liquid and the cleaning liquid from the processing liquid supply unit 15 during polishing. The machining liquid supply unit 15 is connected to the upper end portion of the polishing unit 5 via the machining liquid supply path 16 and supplies the polishing liquid or the cleaning liquid to the polishing unit 5.

  The turntable 6 is a disk-shaped table provided on the upper surface of the apparatus main body 2, is provided so as to be rotatable in a horizontal plane, and is driven to rotate at a predetermined timing. On the turntable 6, for example, four chuck tables 7 are arranged at equal intervals with a phase angle of 90 degrees, for example.

  As shown in FIG. 2, the chuck table 7 includes a holding surface 71 that holds the surface 202 side of the wafer 200 via a protective member 205, and a rotation axis indicated by a one-dot chain line in FIG. 4 that passes through the center 711 of the holding surface 71. 72 and an inclination adjusting mechanism 73 which is an inclination adjusting means shown in FIG. The chuck table 7 has a chuck table structure in which a holding surface 71 includes a vacuum chuck, and holds the wafer 200 placed on the holding surface 71 by vacuum suction.

  As shown in FIG. 4, the holding surface 71 is formed in a conical shape in which the outer peripheral portion 712 is slightly lower than the center 711. That is, the holding surface 71 is formed in a conical surface having the center 711 as a vertex, and is formed as a slope having an inclination that descends from the center 711 toward the outer peripheral portion 712. The chuck table 7 holds the wafer 200 to be processed following the conical surface of the holding surface 71. 4 exaggerates the inclination of the conical surface of the holding surface 71, but the inclination of the conical surface of the holding surface 71 is a slight inclination that cannot be recognized by the naked eye.

  The rotation shaft 72 is the rotation center of the chuck table 7. The rotating shaft 72 is disposed slightly tilted with respect to the vertical direction Z. For this purpose, a portion 713 of the conical surface of the holding surface 71 is arranged along the horizontal direction as shown in FIG. A portion 713 along the horizontal direction of the conical surface of the holding surface 71 and a portion 561 facing the vertical direction Z with the portion 713 of the polishing surface 56 are processing points at which the polishing pad 51 polishes the back surface 201 of the wafer 200. is there. FIG. 4 exaggerates the inclination θ of the rotation shaft 72 with respect to the vertical direction Z, but this inclination θ is a slight angle that cannot be recognized by the naked eye.

  The tilt adjustment mechanism 73 is attached to each chuck table 7. The inclination adjusting mechanism 73 is for changing (adjusting) the inclination θ of the rotating shaft 72 with respect to the vertical direction Z. As shown in FIG. 5, the tilt adjustment mechanism 73 includes a support base 74 and a position adjustment unit 75 connected to the support base 74. The support base 74 includes a cylindrical support cylinder portion 741 that rotatably supports the chuck table 7 via a bearing (not shown), and a flange portion 742 that has a diameter increased from the support cylinder portion 741. The inclination adjustment mechanism 73 adjusts the inclination θ of the rotating shaft 72 by adjusting the inclination of the flange portion 742.

  Two or more position adjustment units 75 shown in FIG. 5 are provided at equal intervals along the arc of the flange portion 742. In the first embodiment, the tilt adjustment mechanism 73 is arranged with two position adjustment units 75 and a fixing portion (not shown) that fixes the flange portion 742 at intervals of 120 degrees. Three or more may be arranged.

  As shown in FIG. 5, the position adjustment unit 75 includes a cylindrical portion 751 fixed to the turntable 6, a shaft 752 penetrating the cylindrical portion 751, a drive portion 753 connected to the lower end of the shaft 752, and a shaft 752. And a fixing portion 754 fixed to the flange portion 742 at the upper end of the. The drive unit 753 includes a motor 755 that rotates the shaft 752 and a speed reducer 756 that weakens the rotational speed of the shaft 752 and is fixed to the turntable 6.

  The fixing portion 754 is engaged with a male screw (not shown) formed at the upper end portion of the shaft 752. The position adjustment unit 75 adjusts the inclination θ of the rotating shaft 72 by the motor 755 rotating the shaft 752 around the axis via the speed reducer 756. In addition, a motor 76 that rotates the chuck table 7 about the rotation shaft 72 is attached to the turntable 6.

  The chuck table 7 is rotationally driven by a motor 76 around the rotation shaft 72 during grinding and polishing. Such a chuck table 7 is sequentially moved to a carry-in / carry-out position 101, a rough grinding position 102, a finish grinding position 103, a polishing position 104, and a carry-in / carry-out position 101 by the rotation of the turntable 6.

  The cassettes 8 and 9 are containers for storing a wafer 200 having a plurality of slots. One cassette 8 accommodates a wafer 200 having a protective member 205 attached to a surface 202 before grinding and polishing, and the other cassette 9 accommodates a wafer 200 after grinding and polishing. The alignment unit 10 is a table on which the wafer 200 taken out from the cassette 8 is temporarily placed and its center is aligned.

  The carry-in unit 11 has a suction pad, sucks and holds the wafer 200 before grinding and polishing, which is aligned by the alignment unit 10, and carries it on the chuck table 7 positioned at the carry-in / out position 101. The carry-in unit 11 sucks and holds the ground and polished wafer 200 held on the chuck table 7 located at the carry-in / out position 101 and carries it out to the cleaning unit 13.

  The carry-in / out unit 14 is, for example, a robot pick provided with a U-shaped hand 141, and conveys the wafer 200 by suction holding with the U-shaped hand 141. Specifically, the carry-in / out unit 14 carries out the wafer 200 before grinding / polishing from the cassette 8 to the alignment unit 10 and carries the wafer 200 after grinding / polishing into the cassette 9 from the cleaning unit 13. The cleaning unit 13 cleans the wafer 200 after grinding and polishing, and removes contamination such as grinding scraps and polishing scraps adhering to the ground and polished processed surface.

  The control device 100 controls each of the above-described components constituting the grinding / polishing device 1. That is, the control device 100 causes the grinding / polishing device 1 to perform a grinding / polishing operation on the wafer 200. The control device 100 is a computer that can execute a computer program. The control device 100 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a read only memory (ROM) or a random access memory (RAM), and an input / output interface device. And have. The CPU of the control device 100 executes a computer program stored in the ROM on the RAM, and generates a control signal for controlling the grinding and polishing device 1. The CPU of the control device 100 outputs the generated control signal to each component of the grinding and polishing device 1 via the input / output interface device. In addition, the control device 100 is connected to a display unit (not shown) configured by a liquid crystal display device or the like that displays a processing operation state or an image, or an input unit used when an operator registers processing content information. . The input unit includes at least one of a touch panel provided on the display unit, a keyboard, and the like.

  The control device 100 stores polishing conditions shown in Table 1 below. The polishing conditions shown in Table 1 are the inclination θ1 of the rotating shaft 72 at the polishing position 104 at the initial processing, which is an initial processing condition, and the inclination θ2 of the rotating shaft 72 at the polishing position 104, at the continuous processing condition, which is a continuous processing condition. Two types are set.

  The control device 100 performs an idling operation (warm-up operation) when starting up the grinding / polishing apparatus 1 that starts the grinding / polishing processing from a state where the grinding / polishing of the wafer 200 is not performed, such as primary interruption of the processing. In the idling operation, the control device 100 rotates the chuck table 7 at the same rotational speed during grinding and polishing without grinding the wafer 200, and supplies a grinding water adjusted to a predetermined temperature while grinding the grinding unit. In addition to rotating the 3 and 4 grinding wheels 32 and 42 at the same rotational speed as during grinding, the idle operation is performed in which the polishing tool 54 of the polishing unit 5 is rotated at the same rotational speed as during polishing. The idling operation is an operation for adjusting each part of the grinding and polishing apparatus 1 to the same temperature as when the wafer 200 is ground and polished so that the grinding and polishing can be performed with a predetermined accuracy. The controller 100 actually performs grinding and polishing of the wafer 200 after performing idling operation for a predetermined time (for example, 30 minutes).

  The initial processing shown in Table 1 is processing for polishing the first wafer 200 after the idling operation. The inclination θ1 of the rotating shaft 72 at the time of initial machining is the inclination θ of the rotating shaft 72 when the first wafer 200 after the idling operation is polished, and is an inclination θ for forming the wafer 200 with a predetermined accuracy. is there. That is, the inclination θ1 of the rotating shaft 72 at the time of initial machining is an inclination θ for suppressing variation in thickness of the first wafer 200 after the idling operation to a predetermined accuracy or less.

  The continuous processing shown in Table 1 is processing for polishing the second and subsequent wafers 200 after the idling operation. The inclination θ2 of the rotating shaft 72 during continuous machining is the inclination θ of the rotating shaft 72 when polishing the second and subsequent wafers 200 after the idling operation, and the inclination θ for forming the wafer 200 with a predetermined accuracy. It is. That is, the inclination θ2 of the rotating shaft 72 during the continuous machining is an inclination θ for suppressing variation in thickness of the second and subsequent wafers 200 after the idling operation to a predetermined accuracy or less.

  Thus, the polishing conditions of the wafer processing method of the present invention shown in Table 1 are the initial processing conditions for polishing the first wafer 200 after the idling operation, and the second and subsequent wafers after the idling operation. Two types of continuous processing conditions for polishing 200 are set.

  The inclination θ1 of the rotating shaft 72 during initial machining is smaller than the inclination θ2 of the rotating shaft 72 during continuous machining, and is set as follows, for example. FIG. 6 is a plan view for explaining measurement points at which the removal amount per unit time of the wafer at the time of initial machining and continuous machining is measured. FIG. 7 is a diagram showing a measurement result of the removal amount per unit time at the time of initial machining of each measurement point shown in FIG. FIG. 8 is a diagram showing a measurement result of the removal amount per unit time at the time of continuous machining of each measurement point shown in FIG.

  The removal amount per unit time indicates the thickness of the wafer 200 that is reduced (thinned) per unit time. Among the measurement points shown in FIG. 6, measurement points “1” and “9” are arranged at the outer edge of the wafer 200, and measurement point “5” is arranged at the center of the wafer 200. The measurement points shown in FIG. 6 are the measurement points “4”, “3”, and “2” arranged at equal intervals from the measurement point “5” to the measurement point “1”. Measurement points “6”, “7” and “8” were arranged at equal intervals toward “9”. FIG. 7 shows the removal amount per unit time of each measurement point at the time of initial machining when the inclination θ of the rotation shaft 72 is set to the inclination θ2 of the rotation shaft 72 in the continuous machining conditions shown in Table 1. FIG. 8 shows the removal amount per unit time of each measurement point during continuous machining when the gradient θ of the rotary shaft 72 is set to the tilt θ2 of the rotary shaft 72 under the continuous machining conditions shown in Table 1.

  According to FIGS. 7 and 8, the removal amount per unit time of the measurement point “5” at the initial machining is smaller than the removal amount per unit time of the measurement point “5” at the time of continuous machining. Therefore, in order to bring the removal amount per unit time of the measurement point “5” at the time of initial machining closer to the removal amount per unit time of the measurement point “5” at the time of continuous machining, the measurement point “ It is necessary to make the pressure in contact with the polishing pad 51 of 5 ”higher than the pressure in contact with the polishing pad 51 at the measurement point“ 5 ”at the time of continuous processing, and the inclination θ1 at the initial processing is greater than the slope θ2 at the continuous processing. Need to be smaller. Note that the removal amount per unit time at the measurement point “5”, that is, the center of the wafer 200 corresponds to the polishing rate described in claim 1.

  As described above, the initial processing conditions of the polishing method of the wafer processing method of the present invention shown in Table 1 are the polishing rate when the first wafer 200 after the idling operation is polished under the initial processing conditions, and the continuous rate. The polishing rate when polishing the second and subsequent wafers 200 after the idling operation under the processing conditions is set to be the same. That is, the polishing rate when polishing the first wafer 200 after the idling operation under the initial processing conditions is the same as the polishing rate when polishing the second and subsequent wafers 200 after the idling operation under the continuous processing conditions. Is set to bring the removal amount of the measurement point “5” shown in FIG. 7 closer to the removal amount of the measurement point “5” shown in FIG. The polishing rate when polishing the first wafer 200 after the idling operation under the initial processing conditions is the same as the polishing rate when polishing the second and subsequent wafers 200 after the idling operation under the continuous processing conditions. This setting means that the removal amount of each measurement point when polishing the first wafer 200 after the idling operation under the initial processing conditions and the second and subsequent wafers 200 after the idling operation under the continuous processing conditions. The removal amount of each measurement point at the time of polishing is not limited to being completely coincident.

  Next, the wafer processing method according to the first embodiment will be described. FIG. 9 is a flowchart showing the flow of the wafer processing method according to the first embodiment. FIG. 10 is a sectional side view showing the initial processing of the grinding / polishing step of the wafer processing method shown in FIG. FIG. 11 is a sectional side view showing the continuous processing of the grinding / polishing step of the wafer processing method shown in FIG.

  The wafer processing method according to the first embodiment (hereinafter simply referred to as a processing method) is a method in which the grinding and polishing apparatus 1 performs rough grinding, finish grinding, and polishing on the wafer 200 in this order. As shown in FIG. 9, the processing method includes at least an idling step ST1 and a grinding / polishing step ST2 which is a polishing step. In the processing method, the operator attaches the cassette 8 containing the wafer 200 in which the protective member 205 before grinding and polishing is adhered to the surface 202 and the cassette 9 not containing the wafer 200 to the apparatus main body 2. In the processing method, when an operator registers processing information in the control device 100 and an operator inputs an instruction to start a processing operation to the grinding and polishing device 1, an idling step ST1 and a grinding and polishing step ST2 are sequentially performed.

  The idling step ST1 is a step of driving the polishing unit 5 or the like (idle operation), that is, performing the idling operation for a predetermined time. In the idling step ST1, the control device 100 performs an idling operation for each component of the grinding / polishing device 1 for a predetermined time. In the processing method, when each component is idling for a predetermined time, the process proceeds to the grinding / polishing step ST2.

  The grinding / polishing step ST2 is a step for polishing the wafer 200 held on the chuck table 7 with the polishing pad 51 after the idling step ST1. In the grinding / polishing step ST2, the control device 100 of the grinding / polishing apparatus 1 causes the carry-in / out unit 14 to take out the wafer 200 from the cassette 8, carry it out to the alignment unit 10, and cause the alignment unit 10 to align the center of the wafer 200. Then, the surface 202 side of the wafer 200 aligned with the carry-in unit 11 is carried onto the chuck table 7 located at the carry-in / out position 101.

  In the grinding / polishing step ST <b> 2, the control device 100 of the grinding / polishing apparatus 1 holds the front surface 202 side of the wafer 200 on the chuck table 7 via the protective member 205, exposes the back surface 201, and the turntable 6 moves the wafer 200. The substrate is sequentially transferred to the rough grinding position 102, the finish grinding position 103, the polishing position 104, and the carry-in / out position 101, and then ground, finish grinding, and polishing are sequentially performed to flatten the back surface 201 of the wafer 200 with high accuracy. In the grinding / polishing step ST2, the grinding / polishing apparatus 1 carries the wafer 200 before grinding / polishing to the chuck table 7 at the carry-in / out position 101 every time the turntable 6 rotates 90 degrees.

  The control device 100 sets the polishing conditions in the grinding / polishing step ST2 to the polishing conditions shown in Table 1. That is, the polishing conditions in the grinding / polishing step ST2 are the inclination θ1 of the rotating shaft 72 at the initial processing, which is the initial processing condition for polishing the first wafer 200 after the idling operation, and the second and subsequent sheets after the idling operation. Two types are set, the inclination θ2 of the rotating shaft 72 during continuous processing, which is a continuous processing condition for polishing the wafer 200. In addition, since the inclination θ1 of the rotating shaft 72 at the time of initial machining is set as described above, the inclination θ1 of the rotating shaft 72 at the time of initial machining, which is an initial machining condition, is the inclination of the rotating shaft 72 at the time of initial machining. The polishing rate when the first wafer 200 after idling operation is polished at θ1 and the polishing rate when the second and subsequent wafers 200 after idling operation are polished at the inclination θ2 of the rotating shaft 72 during continuous processing. Are set to be the same.

  In the grinding / polishing step ST2, the control device 100 controls the inclination adjusting mechanism 73 for adjusting the inclination θ of the rotating shaft 72 of the chuck table 7 at the polishing position 104 to polish the first wafer 200 after the idling operation. At this time, as shown in FIG. 10, polishing is performed by adjusting the inclination θ of the rotating shaft 72 of the chuck table 7 at the polishing position 104 to the inclination θ1. In the grinding / polishing step ST2, the control device 100 controls the inclination adjusting mechanism 73 for adjusting the inclination θ of the rotating shaft 72 of the chuck table 7 at the polishing position 104 to polish the second and subsequent wafers 200 after the idling operation. At this time, as shown in FIG. 11, polishing is performed by adjusting the inclination θ of the rotation shaft 72 of the chuck table 7 at the polishing position 104 to the inclination θ2.

  In this way, in the grinding / polishing step ST2, the control device 100 polishes the second and subsequent wafers 200 with the inclination θ1 when polishing the first wafer 200 in the grinding / polishing step ST2 after the idling step ST1. In this case, the inclination is smaller than θ2. Thus, the initial processing condition is that the angle θ3 formed between the polishing pad 51 and the chuck table 7 shown in FIG. 10 in the portion 561 that is the processing point of the polishing surface 56 of the polishing pad 51 and the portion 713 of the holding surface 71 is as shown in FIG. The inclination θ1 of the rotating shaft 72 is set so as to be larger than the continuous machining conditions shown in FIG. 10 and 11 exaggerate the inclination, inclination θ1, θ2, and angle θ3 of the conical surface of the holding surface 71, as in FIG. 4, but these are so far that they cannot be recognized by the naked eye. Slight inclination, inclination and angle.

  The grinding / polishing apparatus 1 positions the wafer 200 polished by the polishing unit 5 at the carry-in / out position 101, carries it into the cleaning unit 13 by the carry-in unit 11, cleans it with the cleaning unit 13, and carries out the washed wafer 200 with the carry-in / out unit. 14 is carried into the cassette 9. When the grinding / polishing apparatus 1 performs grinding / polishing on all the wafers 200 in the cassette 8, the processing method ends.

  As described above, in the processing method according to the first embodiment, the first wafer 200 after the idling operation is polished with the inclination θ1 of the rotating shaft 72 at the initial processing being the inclination θ1 of the rotating shaft 72 at the initial processing. The polishing rate when polishing the second and subsequent wafers 200 after the idling operation with the inclination θ2 of the rotating shaft 72 during continuous processing is set to be the same. The difference between the polishing rate of the subsequent first wafer 200 and the polishing rate of the second and subsequent wafers 200 can be suppressed. As a result, the processing method according to the first embodiment has an effect that it is possible to suppress variation between the polishing rate during processing of the first wafer 200 after the idling operation and the polishing rate during continuous processing.

  In addition, in the processing method according to the first embodiment, the inclination θ1 of the rotating shaft 72 at the time of initial processing is such that the polishing pad 51 is in a part 561 where the polishing surface 56 of the polishing pad 51 is a processing point and a part 713 of the holding surface 71. And the chuck table 7 are set so as to be larger than the continuous processing condition, the polishing rate of the first wafer 200 after the idling operation and the polishing rate of the second and subsequent wafers 200 are set. The difference can be suppressed.

[Embodiment 2]
A wafer processing method according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 12 is a diagram for explaining the inclination of the rotation axis during the initial processing of the wafer processing method according to the second embodiment.

  In the wafer processing method according to the second embodiment (hereinafter simply referred to as a processing method), the control device 100 has a relationship 300 between the waiting time from immediately before the processing shown in FIG. 12 and the inclination θ1 of the rotating shaft 72 during the initial processing. Is stored, and the inclination θ1 when the first wafer 200 is polished after the idling step ST1 is changed according to the waiting time from the immediately preceding processing. In the processing method according to the second embodiment, the inclination θ1 when polishing the first wafer 200 in the grinding / polishing step ST2 after the idling step ST1 is reduced as the standby time from the immediately preceding processing becomes longer. The immediately preceding machining may be at the start of the immediately preceding machining or at the end of the immediately preceding machining. The standby time refers to the time during which the standby state is maintained, and the standby state refers to all states that are not processed (including both the idling operation state and the idling operation stop state). Say.

  As described above, in the machining method according to the second embodiment, as in the first embodiment, the inclination θ1 of the rotating shaft 72 at the initial machining is equal to the inclination θ1 of the rotating shaft 72 at the initial machining, and one sheet after the idling operation. The polishing rate when polishing the first wafer 200 is set to be the same as the polishing rate when polishing the second and subsequent wafers 200 after idling operation with the inclination θ2 of the rotating shaft 72 during continuous processing. Therefore, the difference between the polishing rate of the first wafer 200 after the idling operation and the polishing rate of the second and subsequent wafers 200 can be suppressed. As a result, the processing method according to the second embodiment has an effect that it is possible to suppress variations between the polishing rate during processing of the first wafer 200 after the idling operation and the polishing rate during continuous processing.

  In the processing method according to the second embodiment, the inclination θ1 when polishing the first wafer 200 in the grinding / polishing step ST2 after the idling step ST1 is reduced as the standby time from the immediately preceding processing becomes longer. Therefore, the difference between the polishing rate of the first wafer 200 after the idling operation and the polishing rate of the second and subsequent wafers 200 can be suppressed.

[Modification]
A wafer processing method according to a modification of Embodiments 1 and 2 of the present invention will be described with reference to the drawings. FIG. 13 is a perspective view of a configuration example of a polishing apparatus used in a wafer processing method according to a modification of the first and second embodiments. In FIG. 13, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A wafer processing method (hereinafter simply referred to as a processing method) according to a modification of the first and second embodiments uses a polishing apparatus shown in FIG. The polishing apparatus 1-1 shown in FIG. 13 has the same configuration as the grinding / polishing apparatus 1 except that the first grinding unit 3 and the second grinding unit 4 are not provided but only the polishing unit 5 is provided. It is.

  In the machining method according to the modified example, the first wafer 200 after the idling operation is polished with the inclination θ1 of the rotating shaft 72 at the initial machining and the inclination θ1 of the rotating shaft 72 at the initial machining, as in the first embodiment. Since the polishing rate at the time of polishing is set to be the same as the polishing rate at the time of polishing the second and subsequent wafers 200 after the idling operation with the inclination θ2 of the rotating shaft 72 during continuous processing. The difference between the polishing rate of the first wafer 200 after operation and the polishing rate of the second and subsequent wafers 200 can be suppressed. As a result, the processing method according to the modified example has an effect that it is possible to suppress variation between the polishing rate during processing of the first wafer 200 after the idling operation and the polishing rate during continuous processing.

In addition, according to the processing method which concerns on Embodiment 1 mentioned above, the following polishing apparatuses are obtained.
(Appendix 1)
A chuck table for holding the wafer;
A polishing means including a polishing pad for polishing the wafer held on the chuck table, a spindle on which the polishing pad is mounted, and a motor for rotationally driving the spindle;
Processing feed means for processing and feeding the polishing means;
A polishing apparatus comprising: a control device that controls each component;
The chuck table includes an inclination adjusting unit that adjusts an inclination of a rotation shaft that passes through a center of a holding surface that holds the wafer.
The control device includes a vertical direction of the rotating shaft when polishing the first wafer in the polishing step in which the wafer held by the chuck table is polished by the polishing pad after the idling step for driving the polishing means is performed. The polishing apparatus is characterized in that the inclination with respect to is smaller than the inclination with respect to the vertical direction of the rotating shaft when polishing the second and subsequent wafers.

  In the polishing apparatus, as in the processing method according to the first embodiment, the initial processing conditions are the polishing rate when the first wafer after the idling operation is polished under the initial processing conditions, and the idling operation under the continuous processing conditions. Since the polishing rate when polishing the second and subsequent wafers is set to be the same, the polishing rate of the first wafer after the idling operation and the polishing rate of the second and subsequent wafers are set. The difference can be suppressed. As a result, the polishing apparatus has an effect that it is possible to suppress variation between the polishing rate during processing of the first wafer after the idling operation and the polishing rate during continuous processing.

  In addition, this invention is not limited to the said embodiment and modification. That is, various modifications can be made without departing from the scope of the present invention.

1 Grinding and polishing equipment (polishing equipment)
1-1 Polishing device 7 Chuck table 5 Polishing unit (polishing means)
12 Processing feed unit (processing feed means)
51 Polishing pad 52 Spindle 53 Motor 561 Part (processing point)
71 Holding surface 72 Rotating shaft 73 Tilt adjusting mechanism (Tilt adjusting means)
711 Center 712 Outer peripheral part 713 Part (processing point)
200 Wafer θ Inclination of rotation axis θ1 Inclination of rotation axis during initial machining (initial machining conditions)
θ2 Tilt of rotation axis during continuous machining (Continuous machining conditions)
θ3 angle ST1 Idling step ST2 Grinding polishing step (polishing step)

Claims (2)

A chuck table for holding the wafer;
A polishing means including a polishing pad for polishing the wafer held on the chuck table, a spindle on which the polishing pad is mounted, and a motor for rotationally driving the spindle;
A processing method of a wafer using a polishing apparatus provided with a processing feed means for processing and feeding the polishing means,
An idling step for driving the polishing means;
A polishing step of polishing the wafer held on the chuck table with the polishing pad after performing the idling step;
Comprising at least
Polishing conditions in the polishing step are:
Initial processing conditions for polishing the first wafer,
Two types of continuous processing conditions for polishing the second and subsequent wafers are set,
The initial processing conditions are:
A polishing rate when the first wafer is polished under the initial processing conditions;
A method for processing a wafer, characterized in that the polishing rate when polishing the second and subsequent wafers under the continuous processing conditions is set to be the same. The chuck table
A conical holding surface whose outer periphery is slightly lower than the center;
A rotation axis passing through the center of the holding surface;
An inclination adjusting means for adjusting the inclination of the rotating shaft,
The initial processing conditions are:
The inclination of the rotating shaft is set so that the angle formed between the polishing pad and the chuck table at a processing point is larger than the continuous processing conditions,
The wafer processing method according to claim 1.

Images