Wafer processing method and processing device

Abstract

To easily form a wafer to a set finishing thickness distribution even when a portion having a locally large thickness is generated on the wafer.SOLUTION: The present invention is a processing method for etching the upper surface of a wafer (W) into a predetermined thickness shape by irradiating the upper surface with plasmatized etching gas from an irradiation unit (50). The method includes a thickness distribution acquisition step of acquiring the thickness distribution of the entire upper surface of the wafer, a calculation step of calculating the irradiation position of the irradiation unit relative to the wafer and the irradiation amount of etching gas at the irradiation position on the basis of the difference between the thickness distribution acquired in the thickness distribution acquisition step and a predetermined finished thickness distribution, and an etching step of irradiating the upper surface of the wafer with the irradiation amount at the irradiation position calculated in the calculation step, thereby etching the upper surface of the wafer into the predetermined thickness shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer processing method and processing apparatus for processing a wafer to a uniform thickness. [Background technology]

[0002] In the grinding device of Patent Document 1, a chuck table holding a wafer rotates, and a grinding stone arranged in a ring on a grinding wheel rotates and comes into contact with the wafer, grinding the wafer. In this grinding device, the inclination of the chuck table relative to the grinding stone is adjusted so that the ground wafer has a set uniform thickness distribution.

[0003] In addition, in the polishing apparatus of Patent Document 2, polishing is performed by bringing the wafer and polishing pad into rotating contact. In this polishing apparatus, the radial thickness distribution of the wafer is measured, and based on that thickness distribution, the polishing pad is dressed by a dressing mechanism to polish the wafer to a set uniform thickness distribution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-119123 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-223636 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Documents 1 and 2, wafers are ground or polished to a uniform thickness, and if locally thick portions are formed in the circumferential or radial direction of the wafer, resulting in an uneven thickness distribution, it becomes difficult to process the thick portions until they have the same thickness as the other portions.

[0006] Furthermore, when a thick portion is processed to a set thickness, the processing proceeds so that other portions become thinner than the set thickness, and when other portions are processed to a set thickness, the thick portion becomes thicker than the set thickness. Therefore, when a locally thick portion occurs on the wafer, there is a problem in that it is not possible to process the wafer to eliminate thickness differences.

[0007] The present invention has been made in consideration of the above points, and one of its objects is to provide a wafer processing method and processing apparatus that can easily form a wafer to a set finished thickness distribution even if locally thick portions occur on the wafer. [Means for solving the problem]

[0008] A wafer processing method according to one embodiment of the present invention is a wafer processing method in which plasmatized etching gas is irradiated onto one side of a wafer from an irradiation unit to etch the one side of the wafer into a predetermined thickness shape, and comprises: a thickness distribution acquisition step of acquiring a thickness distribution over the entire surface of the wafer; a calculation step of calculating the irradiation position of the irradiation unit on the wafer and the irradiation amount of the etching gas at the irradiation position based on the difference between the thickness distribution acquired in the thickness distribution acquisition step and a predetermined finished thickness distribution; and an etching step of irradiating the one side of the wafer with the irradiation amount at the irradiation position calculated in the calculation step, thereby etching the one side of the wafer into a predetermined thickness shape.

[0009] A processing apparatus according to one embodiment of the present invention includes a chuck table for holding a wafer and an irradiation unit for etching the wafer held on the chuck table by irradiating plasmatized etching gas, and further includes a horizontal movement mechanism for relatively moving the chuck table and the irradiation unit in a horizontal direction, a calculation unit for calculating the amount of etching of the wafer at the irradiation position of the irradiation unit by the horizontal movement mechanism based on the difference between a previously acquired thickness distribution over the entire surface of the wafer and a previously set finishing thickness distribution, and a control unit for controlling the etching amount to be the amount calculated by the calculation unit. [Effects of the Invention]

[0010] According to the present invention, even if a locally thick portion occurs on a wafer, the etching amount of the thick portion can be locally increased by calculating the irradiation amount of the etching gas at the irradiation position of the etching gas according to the formation position of the thick portion, and the vertical distance of the irradiation portion in addition to the irradiation amount. As a result, the thick portion can be etched to the same thickness as the other portions, and the wafer can be easily formed into a predetermined thickness shape. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic perspective view of a processing device according to an embodiment; [Figure 2] FIG. 2 is an enlarged explanatory view of an etching apparatus. [Figure 3] FIG. 2 is an explanatory diagram of a processing device including a control unit. [Figure 4] FIG. 10 is an explanatory diagram of a thickness distribution acquisition step. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 10 is a schematic perspective view of a processing device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a processing device according to an embodiment will be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the processing device according to the embodiment;

[0013] As shown in Figure 1, the processing device 1 etches one side of a wafer W, which is a workpiece formed in a substantially circular disk shape, to form a predetermined thickness. The wafer W may be any plate-shaped workpiece that can be etched, and examples of such materials include silicon materials such as Si, SiO2, and SiN. The surface of the wafer W to be etched is the upper surface. A protective tape T is attached to the lower surface of the wafer W.

[0014] The X-axis, Y-axis, and Z-axis directions of the processing device 1 are perpendicular to one another. The X-axis and Y-axis directions are approximately horizontal, and the Z-axis direction is an up-down direction (vertical direction). Of the two arrows indicating the X-axis direction, the +X side is the right side and the -X side is the left side. Of the two arrows indicating the Y-axis direction, the +Y side is the front side and the -Y side is the rear side. Of the two arrows indicating the Z-axis direction, the +Z side is the up side and the -Z side is the down side.

[0015] A rectangular opening 11 extending in the Y-axis direction is formed on the upper surface of a base 10 in the processing device 1. The processing device 1 is equipped with a movable plate 12 that covers the opening 11, a bellows-shaped waterproof cover 13, and a chuck table 14. The movable plate 12 and the waterproof cover 13 are provided so as to be movable in the Y-axis direction together with the chuck table 14.

[0016] The chuck table 14 includes a frame 15, a porous plate 16 fitted into a recess formed in the upper surface of the frame 15, and a cylindrical chuck spindle 17 provided below the frame 15. The frame 15 is formed with a suction path 18 (see FIG. 2) that connects the upper surface of the recess in which the porous plate 16 is fitted to a suction source (not shown), and a negative pressure is generated on the surface (upper surface) of the porous plate 16 by the suction action of the suction source. The chuck table 14 suction-holds the wafer W using the surface of the porous plate 16 where the negative pressure is generated as a holding surface 19.

[0017] A horizontal movement mechanism 20 that moves the chuck table 14 in the horizontal direction and an inclination adjustment mechanism 21 that adjusts the inclination of the chuck table 14 are provided below the waterproof cover 13. The horizontal movement mechanism 20 includes a Y-axis movement mechanism 22 that serves as a linear motion mechanism, and a table rotation mechanism 23.

[0018] The Y-axis moving mechanism 22 is a ball screw type electric slider. The Y-axis moving mechanism 22 includes a ball screw 25 and a guide rail 26 extending in the Y-axis direction, a motor 27 connected to one end of the ball screw 25, and a slide unit 28 slidably installed on the guide rail 26. A nut unit (not shown) that screws onto the ball screw 25 is formed on the back surface of the slide unit 28. In the Y-axis moving mechanism 22, the slide unit 28 moves in the Y-axis direction due to rotation of the motor 27, and accordingly, the chuck table 14 supported by the slide unit 28 moves in the Y-axis direction.

[0019] The table rotation mechanism 23 includes a motor 31, a belt pulley 32 provided on the output shaft of the motor 31, and a belt 33 wound around the belt pulley 32 and the chuck spindle 17. When the motor 31 rotates the belt pulley 32, the rotational force is transmitted to the chuck spindle 17 via the belt 33. As a result, the rotation of the chuck spindle 17 rotates the chuck table 14 around a central axis parallel to the Z axis.

[0020] The tilt adjustment mechanism 21 includes a support base 35, a position adjustment unit 36 ​​connected to the support base 35, and a fixed support portion (not shown). The support base 35 includes a cylindrical portion 38 into which the chuck spindle 17 is inserted, and a disk-shaped flange portion 39 formed by expanding the diameter of the lower portion of the cylindrical portion 38. A bearing disposed inside the cylindrical portion 38 contacts the outer peripheral surface of the chuck spindle 17, and the chuck spindle 17 is rotatably supported by the cylindrical portion 38 via the bearing. The tilt adjustment mechanism 21 adjusts the tilt of the flange portion 39 by driving the position adjustment unit 36, thereby functioning to adjust the tilt of the chuck spindle 17 and the chuck table 14.

[0021] The processing apparatus 1 further includes a thickness gauge 41 that is mounted on the base 10 and measures the thickness of the wafer W held on the chuck table 14. The thickness gauge 41 may be, for example, a type that uses measurement light or ultrasonic waves to perform non-contact measurement with the wafer W. The type that uses measurement light receives upper-surface reflected light from the upper surface of the wafer W and lower-surface reflected light from the lower surface of the wafer W with a sensor, and measures the thickness of the wafer W using a spectral interference method based on the principle that the upper-surface reflected light and the lower-surface reflected light interfere with each other. The measurement light may be, for example, laser light or infrared SLD. The type that uses ultrasonic waves emits ultrasonic waves from above the wafer W, receives ultrasonic vibrations reflected from the upper surface of the wafer W and ultrasonic vibrations reflected from the lower surface of the wafer W, and measures the thickness of the wafer W based on the propagation time of the ultrasonic waves.

[0022] The thickness gauge 41 is supported at the tip end of a rotating arm 42, and the base end of the rotating arm 42 is supported via a rotating mechanism 43 installed on the upper surface of the base 10. The rotating mechanism 43 is provided so as to rotate and displace the rotating arm 42 about an axis parallel to the Z-axis direction, thereby moving the thickness gauge 41 in the horizontal direction. More specifically, by driving the rotating mechanism 43, the thickness gauge 41 can be moved between a position directly above the center of the chuck table 14 and a position on the periphery thereof. Therefore, by driving the rotating mechanism 43 while rotating the chuck table 14 and moving the thickness gauge 41 between the center and the periphery of the chuck table 14, it is possible to evenly measure the thickness of the entire upper surface of the wafer W held on the chuck table 14 and obtain the thickness distribution.

[0023] The processing apparatus 1 further includes a lifting mechanism 45 and an etching device 46 provided on the base 10.

[0024] The lifting mechanism 45 includes a support arm 47 that supports an irradiation unit 50 (described later) of the etching device 46 at its tip end, and a drive unit 48 that supports the base of the support arm 47. The support arm 47 supports the irradiation unit 50 so that the position of the irradiation unit 50 in the X-axis direction coincides with the center position of the chuck table 14 in the X-axis direction. Therefore, when the chuck table 14 is moved in the Y-axis direction, the irradiation unit 50 passes directly above the diameter of the holding surface 19 and the wafer W that is parallel to the Y-axis direction.

[0025] The drive unit 48 is not particularly limited, but can be, for example, configured by a cylinder or a linear motor that vertically raises and lowers the support arm 47 and the irradiation unit 50. Thus, the drive unit 48 raises and lowers the chuck table 14 and the irradiation unit 50 relatively in the vertical direction.

[0026] The etching apparatus 46 includes an irradiation unit 50, a plasma generation unit 51 provided above the irradiation unit 50, and an etching gas supply unit 53 that supplies etching gas to the plasma generation unit 51 via a pipe 52. The etching gas supply unit 53 is provided on the base 10 and includes a container that contains the etching gas. The etching gas is a halogen gas. Specifically, since the wafer W is made of the silicon material described above, examples of the etching gas that can be used include CF4, CHF3, and SF6. O and H may be mixed into the etching gas to promote radical generation and increase the etching amount. Furthermore, the etching gas may contain a rare gas such as He, Ne, or Ar to facilitate maintaining discharge. The irradiation unit 50 may be configured to have one irradiation port 55 or to have a plurality of adjacent irradiation ports 55. The irradiation unit 50 may be configured to have a cross-sectional diameter of 10 mm to 30 mm.

[0027] Fig. 2 is an enlarged explanatory view of the etching apparatus. As shown in Fig. 2, the irradiation unit 50 has an irradiation port 55 formed at the bottom end and irradiating plasmatized etching gas, and a suction port 56 formed around the irradiation port 55. The irradiation port 55 is connected to the plasma generation unit 51 via an irradiation flow path 57. The suction port 56 is connected to a suction source 59 via a suction flow path 58. By driving the suction source 59, the etching gas irradiated from the irradiation port 55 is sucked into the suction port 56, preventing the etching gas from scattering around. The suction ports 56 may be arranged in a ring shape around the outside of the irradiation port 55, or may be in a ring shape surrounding the irradiation port 55.

[0028] The plasma generating unit 51 includes a chamber 61 capable of accommodating an etching gas, an electrode 62 provided around the chamber 61, and a supply flow path 63 communicating with the chamber 61. The supply flow path 63 communicates with the etching gas supply unit 53 via a pipe 52. Therefore, in the plasma generating unit 51, the etching gas is supplied to the chamber 61 from the etching gas supply unit 53.

[0029] A high-frequency power supply 65 is connected to the electrode 62, and the electrode 62 applies a high-frequency voltage to the etching gas contained in the chamber 61, thereby changing the etching gas into a plasma state in which radicals exist. The plasmatized etching gas passes through an irradiation flow path 57 and is irradiated from an irradiation port 55.

[0030] FIG. 3 is an explanatory diagram of a processing apparatus including a control unit according to an embodiment. The processing apparatus 1 is provided with a control unit 70 that controls each unit of the apparatus. The control unit 70 includes a processor and memory that execute various processes. The control unit 70 controls various operations, such as measuring the thickness of the wafer W and etching the wafer W, according to a control program stored in the memory. Specifically, the control unit 70 controls the etching amount of the wafer W by the etching device 46, the movement speed of the horizontal movement mechanism 20, the amount of etching gas irradiated from the irradiation unit 50 via a flow rate adjustment unit 72 (described later), and the drive of the lifting mechanism 45. The memory of the control unit 70 temporarily stores processing-related data, such as the thickness distribution of the entire upper surface of the wafer W and the finished thickness distribution of the entire upper surface of the wafer W. Here, the "finished thickness distribution" corresponds to a "predetermined thickness profile" of the wafer W before processing, e.g., a state in which the wafer W is uniformly etched to a finished thickness that is an ideal or target value.

[0031] The control unit 70 includes a calculation unit 71, a flow rate adjustment unit 72, a storage unit 73, and a high-frequency power adjustment unit 74, which are shown as functional blocks in Fig. 3. These functional blocks are realized by the control unit 70 executing a program stored in the memory of the control unit 70. Note that the functional blocks of the control unit 70 shown in Fig. 3 only show configurations related to the present invention, and other configurations are omitted.

[0032] The calculation unit 71 calculates the difference between the thickness distribution of the entire upper surface of the wafer W, which is acquired in advance by measurement by the thickness measuring device 41 or the like, and a preset finished thickness distribution of the entire upper surface of the wafer W. Then, based on the calculated difference, the calculation unit 71 calculates the etching amount of the wafer W at the irradiation position of the irradiation unit 50 in the etching device 46. In this calculation, an arithmetic expression or a data table that defines the relationship (for example, a proportional relationship) between the calculated difference and the etching amount is used.

[0033] The calculation unit 71 calculates the irradiation amount of the etching gas at the irradiation position of the irradiation unit 50 relative to the wafer W and the height (position in the Z-axis direction) of the irradiation unit 50, according to the calculated etching amount of the wafer W. In this calculation, the irradiation position of the irradiation unit 50 relative to the wafer W and the irradiation amount of the etching gas at the irradiation position may be calculated separately, and a process of correlating them may be performed. Furthermore, according to the calculated etching amount of the wafer W, the calculation unit 71 calculates the relative irradiation position of the irradiation unit 50 and the wafer W in the horizontal direction (X-axis and Y-axis directions), and the vertical distance between the irradiation unit 50 and the wafer W at the irradiation position (position in the Z-axis direction). Note that, hereinafter, the vertical distance between the irradiation unit 50 and the wafer W will be described as the "height of the irradiation unit 50."

[0034] The flow rate adjusting unit 72 controls the amount of irradiation of the etching gas irradiated from the irradiation unit 50 in the etching apparatus 46. Examples of this adjustment include varying the total irradiation time of the irradiation unit 50 at the irradiation position of the wafer W, or varying the irradiation amount at the irradiation position. Furthermore, the irradiation amount at the irradiation position may be varied by varying the number of times the etching gas is irradiated at the irradiation position.

[0035] The storage unit 73 acquires the thickness distribution of the entire upper surface of the wafer W based on the measurement data of the thickness of the wafer W measured by the thickness measuring device 41 and the driving conditions of the turning mechanism 43 and the table rotation mechanism 23. This thickness distribution may be set by the position of the entire upper surface of the wafer W in an XY coordinate system, or may be set by the angle around the center of the wafer W and the position in the radial direction.

[0036] The high-frequency power adjusting unit 74 controls the amount of irradiation of the etching gas irradiated from the irradiation unit 50 in the etching device 46. An example of this adjustment is to vary the voltage applied from the high-frequency power supply 65 to the electrode 62 of the plasma generating unit 51.

[0037] In addition, in the case where the control subject is not specified for the operation of each part of the processing device 1 described below, it is assumed that the operation is controlled by a control signal sent from the control unit 70.

[0038] Next, a method for processing the wafer W in the processing apparatus 1 will be described, in which the upper surface, which is one side of the wafer W, is etched to form a predetermined thickness shape. This processing method is performed in the order of a thickness distribution acquisition step, a calculation step, and an etching step. Fig. 4 is an explanatory diagram of the thickness distribution acquisition step, Fig. 5 is an explanatory diagram of the calculation step, and Fig. 6 is an explanatory diagram of the etching step.

[0039] In the following, as wafers W before processing, methods for processing wafers W having the shapes shown in Figures 4A, 5A, and 6A and wafers W having the shapes shown in Figures 4B, 5B, and 6B will be described. The former wafers W have locally increased thickness in a point-like manner or in a predetermined range at one location on their top surface, while the latter wafers W have locally increased thickness in an annular range concentric with the wafer W on their top surface. Furthermore, the wafers W in Figures 4 to 6 are schematically shown with the locally increased thickness exaggerated.

[0040] [Thickness distribution acquisition process] In the thickness distribution acquisition process, after the wafer W is held by suction on the chuck table 14, the chuck table 14 is driven in the Y-axis direction by driving the Y-axis movement mechanism 22. Then, the chuck table 14 is positioned so that the center of the wafer W is located directly below the thickness measuring device 41.

[0041] In this state, the thickness measurement of the wafer W is started by the thickness gauge 41. At this time, the turning mechanism 43 moves the thickness gauge 41 horizontally above the wafer W along the radial direction of the wafer W, and the table rotation mechanism 23 rotates the chuck table 14 and the wafer W. As a result, the thickness gauge 41 moves relative to the wafer W along a spiral trajectory, and the thickness gauge 41 performs measurements continuously or intermittently, thereby measuring the thickness in a matrix or scattered manner at multiple locations over the entire top surface of the wafer W. The thickness measuring device 41 may measure the wafer along a concentric circular path.

[0042] The measurement signal of the thickness measuring device 41 is output to the memory unit 73. Furthermore, detection signals of the rotation speed and rotation angle are output to the memory unit 73 from a detection device (not shown) such as an encoder provided on a motor (not shown) of the rotation mechanism 43 and the motor 31 of the table rotation mechanism 23. Then, the memory unit 73 acquires the thickness distribution of the entire upper surface of the wafer W based on the detection signals and the measurement signal of the thickness measuring device 41.

[0043] For example, the thickness distribution shown in the graph at the bottom is obtained for the wafer W shown in the perspective view at the top and the cross-sectional view at the middle in each of Figures 4A and 4B. In each graph, the horizontal axis represents the position on the cross section indicated by the dashed dotted line in the top view of each of Figures 4A and 4B, and the vertical axis represents the thickness of the wafer W. Therefore, in the thickness distribution shown in the graphs of Figures 4A and 4B, a thickness distribution is obtained in which the thickness increases at positions corresponding to regions where the thickness increases locally.

[0044] [Calculation process] After the thickness distribution acquisition step is performed, a calculation step is performed based on the thickness distribution acquired in the thickness distribution acquisition step. In the calculation step, as illustrated in the graphs of Figures 4A and 4B, the calculation unit 71 calculates the difference between the thickness distribution (shown by the solid line) of the entire upper surface of the wafer W previously acquired in the storage unit 73 and the finished thickness distribution (shown by the dashed line) of the entire upper surface of the wafer W previously set and stored. Here, if the finished thickness distribution is set so that the upper and lower surfaces of the wafer W are parallel, a calculation result is obtained in which the difference between the acquired (measured) thickness distribution and the finished thickness distribution increases at positions corresponding to regions where the thickness is locally increased.

[0045] In the calculation step, the etching amount of the wafer W at the upper surface position of the wafer W is calculated by the calculation unit 71 based on the difference calculated as described above, and the larger the difference, the larger the calculated etching amount. The upper surface position of the wafer W is calculated as the irradiation position of the irradiation unit 50 that irradiates the etching gas on the upper surface side. The etching amount of the wafer W is calculated in association with the irradiation position of the irradiation unit 50.

[0046] In the calculation step, the calculation unit 71 calculates the irradiation amount of the etching gas at the irradiation position of the irradiation unit 50 relative to the wafer W according to the calculated etching amount of the wafer W. For example, the irradiation amount shown in the graph in the middle is calculated for the wafer W shown in the perspective views at the top of each of FIGS. 5A and 5B. In each graph, the horizontal axis represents the position on the cross section indicated by the dashed-dotted line in the top diagram of each of FIGS. 5A and 5B, and the vertical axis represents the irradiation amount of the etching gas. As shown in each graph, a calculation result is obtained showing that the irradiation amount of the etching gas increases at positions corresponding to regions where the thickness increases locally.

[0047] Furthermore, in the calculation step, the height (position in the Z-axis direction) of the irradiation unit 50 at the irradiation position of the irradiation unit 50 relative to the wafer W is calculated by the calculation unit 71 according to the calculated etching amount of the wafer W. For example, for the wafer W shown in the perspective views at the top of each of FIGS. 5A and 5B, the height of the irradiation unit 50 shown in the graphs at the bottom is calculated. In each graph, the horizontal axis represents the position in the cross section indicated by the dashed-dotted line in the top view of each of FIGS. 5A and 5B, and the vertical axis represents the height of the irradiation unit 50. As shown in each graph, a calculation result is obtained showing that the height of the irradiation unit 50 is lower at positions corresponding to regions where the thickness is locally increased.

[0048] [Etching process] After the calculation process is performed, an etching process is performed to etch the wafer W. In the etching process, first, the chuck table 14 is driven in the Y-axis direction by driving the Y-axis moving mechanism 22, and the chuck table 14 is positioned so that the center of the wafer W is located directly below the irradiation unit 50 of the etching device 46.

[0049] In this state, irradiation of the wafer W held on the chuck table 14 with plasmatized etching gas from the irradiation unit 50 begins. At this time, the horizontal movement mechanism 20 moves the chuck table 14 and the irradiation unit 50 relatively in the horizontal direction. Specifically, the Y-axis movement mechanism 22 moves the chuck table 14 and the wafer W so that the irradiation unit 50 is displaced from the center of the wafer W to the outer periphery above the wafer W, and the table rotation mechanism 23 rotates the chuck table 14 and the wafer W. As a result, the irradiation unit 50 moves relative to the wafer W along a spiral trajectory, and the entire top surface of the wafer W held on the chuck table 14 is irradiated with plasmatized etching gas from the irradiation unit 50, thereby etching the wafer.

[0050] The irradiation of the etching gas in the etching step is controlled by the control unit 70 so as to achieve the etching amount calculated by the calculation unit 71 in the calculation step.

[0051] For example, the flow rate adjusting unit 72 in the control unit 70 adjusts the amount of etching gas irradiated depending on when the wafer W, which is moved relative to the irradiating unit 50, passes the irradiation position of the irradiating unit 50. The flow rate adjusting unit 72 controls the amount of etching gas irradiated from the irradiating unit 50 in the etching device 46 using the relationship between the irradiation position of the irradiating unit 50 relative to the wafer W and the amount of etching gas irradiated, calculated in the calculation step, as shown in the middle graphs of each of FIGS. 5A and 5B. This control changes the amount of etching gas irradiated relatively depending on the thickness distribution of the wafer W, and the wafer W is etched to a predetermined thickness profile. Specifically, the amount of etching gas irradiated is increased in areas of the wafer W where the thickness is locally increased compared to other areas, thereby increasing the amount of etching. This etching allows the wafer W to be formed to a uniform thickness, as shown in FIGS. 6A and 6B.

[0052] Furthermore, for example, the control unit 70 may control the amount of etching gas irradiated to the wafer W by controlling the amount of power (voltage variable control) of the high-frequency power adjusting unit 74 in accordance with the timing at which the wafer W, which is moved relative to the irradiation unit 50, passes the irradiation position of the irradiation unit 50. The high-frequency power adjusting unit 74 controls the amount of etching gas irradiated to the wafer W by the etching device 46 using the relationship between the irradiation position of the irradiation unit 50 relative to the wafer W and the amount of etching gas irradiated to the wafer W calculated in the calculation step, as shown in the middle graphs of each of FIGS. 5A and 5B. This control changes the amount of etching gas irradiated to the wafer W relatively in accordance with the thickness distribution of the wafer W, thereby etching the wafer W to a predetermined thickness profile. Specifically, the amount of etching gas irradiated to the locally thickened portions of the wafer W is increased compared to other portions, thereby increasing the amount of etching. This etching allows the wafer W to be formed to a uniform thickness, as shown in FIGS. 6A and 6B.

[0053] The irradiation amount of the etching gas may be adjusted by controlling the control unit 70 to change the movement speed and rotation speed of the Y-axis movement mechanism 22 and the table rotation mechanism 23 in the horizontal movement mechanism 20. In this control, the total irradiation time at the irradiation position of the irradiation unit 50 is changed relatively between the portion of the wafer W where the thickness is locally increased and the other portion, and the wafer W is etched to a predetermined thickness shape. In this control, the control can be made easier by keeping the irradiation amount of the etching gas irradiated from the irradiation unit 50 constant, but this does not prevent the irradiation amount of the etching gas from being changed.

[0054] As another example, the control unit 70 controls the height of the irradiation unit 50 in response to the timing at which the wafer W, moving relative to the irradiation unit 50, passes below the irradiation position of the irradiation unit 50. The control unit 70 controls the driving of the lifting mechanism 45 using the relationship between the irradiation position of the irradiation unit 50 relative to the wafer W and the height of the irradiation unit 50 calculated in the calculation step, as shown in the lower graphs of FIGS. 5A and 5B . This control relatively changes the height of the irradiation unit 50 in response to the thickness distribution of the wafer W, and the wafer W is etched to a predetermined thickness profile. Specifically, the height of the irradiation unit 50 is lowered in areas of the wafer W where the thickness is locally increased compared to other areas, bringing the irradiation unit 50 closer to the wafer W and increasing the amount of etching. This etching allows the wafer W to be formed to a uniform thickness, as shown in FIGS. 6A and 6B .

[0055] According to the above embodiment, even if a portion with a locally increased thickness occurs on the wafer W, the etching amount of that portion can be made larger than that of other portions. In other words, the etching amount can be adjusted according to the thickness at any position on the wafer W, and the wafer W can be easily formed into a predetermined thickness shape, such as by etching a thicker portion to the same thickness as other portions to a uniform thickness.

[0056] 4 and 5, even if the thickness of the wafer W increases locally, the thickness distribution over the entire upper surface of the wafer W can be obtained by measurement using the thickness measuring device 41. This makes it possible to adjust the amount of etching gas irradiated at the irradiation position of the irradiating unit 50 and the height of the irradiating unit 50 according to the obtained thickness distribution, and to easily form the wafer W into a predetermined thickness shape.

[0057] Furthermore, the calculation unit 71 calculates the difference between the thickness distribution over the entire top surface of the wafer W and the finished thickness distribution, and based on this difference, it is possible to calculate the etching amount at the irradiation position of the irradiation unit 50, the irradiation amount of etching gas, the height of the irradiation unit 50, and the amount of high-frequency power. As a result, based on the calculation results, the horizontal movement mechanism 20 and lifting mechanism 45 that move the irradiation unit 50, the high-frequency power adjustment unit 74, and the etching device 46 that irradiates the etching gas can be controlled to etch the top surface of the wafer W to a preset thickness shape.

[0058] The present invention is not limited to the above-described embodiments, and various modifications can be made. In the above-described embodiments, the size and shape shown in the accompanying drawings are not limited to these, and can be modified as appropriate within the scope of the effects of the present invention. In addition, the present invention can be modified as appropriate within the scope of the object of the present invention.

[0059] For example, in the above embodiment, both the irradiation amount of the etching gas and the height of the irradiation section 50 are calculated in the calculation process, but it is also possible to calculate either one of them and control the etching amount of the wafer W using the calculated irradiation amount or the height of the irradiation section 50.

[0060] Furthermore, the control of the etching amount in the etching step does not preclude the simultaneous control of both the calculated irradiation amount of etching gas and the height of the irradiation part 50.

[0061] Furthermore, although the entire upper surface of the wafer W is etched in the etching step, there may be portions on the upper surface of the wafer W that are not etched, such as by spot etching only in thicker portions.

[0062] Furthermore, although the thickness distribution of the wafer W is obtained using the thickness measuring device 41 in the processing device 1, if the thickness distribution of the wafer W has already been obtained before being loaded into the processing device 1, the thickness measuring device 41 may be omitted.

[0063] Furthermore, the processing apparatus of the present invention is not limited to the above-described embodiment, and may be incorporated into processing apparatuses such as grinding apparatuses and polishing apparatuses. A modified example of the processing apparatus is the configuration of a grinding apparatus shown in FIG. 7. FIG. 7 is a schematic perspective view of the modified processing apparatus. In the following description of the modified example, the same reference numerals may be used for components that are the same as or equivalent to those in the above-described embodiment, and descriptions thereof may be omitted or simplified.

[0064] 7 includes three chuck tables 14 for holding wafers W. Each chuck table 14 is rotatable about a central axis parallel to the Z axis passing through the center of the holding surface 19 via a table rotation mechanism (not shown).

[0065] The processing apparatus 100 also includes a turntable 102 that is provided on the upper surface of the base 101 and supports the three chuck tables 14, a support pillar 103 that stands in the center of the turntable 102, and an elevating mechanism 45 that is provided on the upper part of the support pillar 103. The turntable 102 is provided rotatably around a central axis that is parallel to the Z axis, and moves the three chuck tables 14, and is also provided so that the chuck tables 14 can be positioned at one location in front of the center and two locations on the left and right sides behind.

[0066] The lifting mechanism 45 includes a support arm 105 having a drive mechanism that extends parallel to the Y axis and expands and contracts in the Y axis direction. An irradiation unit 50 and a plasma generation unit 51 of an etching device (not shown) are supported at the tip of the support arm 105.

[0067] The irradiation unit 50 is disposed above the chuck table 14, which is positioned in front of the turntable 102. Therefore, the chuck table 14 and the irradiation unit 50 are raised and lowered relative to each other in the vertical direction by driving the lifting mechanism 45. Furthermore, the chuck table 14 and the irradiation unit 50 are moved relative to each other in the horizontal direction by driving the support arm 105 to extend and retract and rotate the chuck table 14. Specifically, the irradiation unit 50 is moved radially above the wafer W from the center toward the outer periphery of the wafer W by driving the support arm 105 to extend and retract, and the chuck table 14 and the wafer W are rotated by a table rotation mechanism (not shown). As a result, the irradiation unit 50 is moved relative to the wafer W along a spiral trajectory, and the entire top surface of the wafer W held on the chuck table 14 is irradiated with plasma-converted etching gas from the irradiation unit 50, thereby etching the wafer.

[0068] The processing apparatus 100 includes a rough grinding mechanism 107 provided on the left side (-X side) behind the base 101, and a finish grinding mechanism 108 provided on the right side (+X side). Each of the grinding mechanisms 107, 108 grinds the upper surface of the wafer W held on the chuck table 14 using a plurality of rotating grinding wheels 109, 110. The grinding wheel 110 of the finish grinding mechanism 108 has a smaller abrasive grain size than the grinding wheel 109 of the rough grinding mechanism 107, and the rough grinding mechanism 107 performs rough grinding on the wafer W, and the finish grinding mechanism 108 performs finish grinding on the wafer W.

[0069] The processing apparatus 100 includes a thickness gauge 41 supported on a base 101 via a swivel arm 42 and a swivel mechanism 43. In the modified example of Fig. 7 as well, when measuring the wafer W with the thickness gauge 41, the swivel mechanism 43 is driven while rotating the chuck table 14, and the thickness gauge 41 is moved between the center and the outer periphery of the chuck table 14. This makes it possible to measure the thickness of the entire top surface of the wafer W held on the chuck table 14 evenly and obtain the thickness distribution.

[0070] 7, etching can be performed by calculating and adjusting the irradiation position of the irradiation unit 50 relative to the wafer W, the amount of etching gas irradiated at the irradiation position, and the height of the irradiation unit 50, thereby forming the wafer W into a predetermined thickness shape. Furthermore, in the processing apparatus 100 of FIG. 7, the wafer W held on the chuck table 14 can be subjected to rough grinding by the rough grinding mechanism 107, finish grinding by the finish grinding mechanism 108, thickness measurement by the thickness gauge 41, and etching by irradiation with the etching gas. In other words, in a single processing apparatus 100, rough grinding, finish grinding, thickness measurement, and etching can be automatically performed in a series of operations while the wafer W is held on the chuck table 14, thereby improving productivity. [Industrial Applicability]

[0071] As described above, the present invention has the effect of easily forming a wafer to have a set finished thickness distribution even if there are locally thick portions on the wafer. [Explanation of symbols]

[0072] 1: Processing equipment 14: Chuck table 20: Horizontal movement mechanism 41: Thickness measuring instrument 45: Lifting mechanism 50: Irradiation unit 55: Irradiation port 56: Suction port 70: Control unit 71: Calculation section 72:Flow rate adjustment section 73: Storage section 74:High frequency power adjustment section 100: Processing equipment 105: Support arm (horizontal movement mechanism) W: wafer

Claims

1. A wafer processing method in which plasmatized etching gas is irradiated onto one side of a wafer from an irradiation unit to etch the one side of the wafer into a predetermined thickness shape, comprising: a thickness distribution acquisition step of acquiring a thickness distribution over the entire surface of the wafer; a calculation step of calculating an irradiation position of the irradiation unit on the wafer and an irradiation amount of the etching gas at the irradiation position based on a difference between the thickness distribution acquired in the thickness distribution acquisition step and a preset finished thickness distribution; an etching step of irradiating one side of the wafer with the irradiation amount at the irradiation position calculated in the calculation step, and etching the one side of the wafer to form the wafer into a predetermined thickness shape.

2. 2. The wafer processing method according to claim 1, wherein the calculating step calculates the height of the irradiated portion relative to the wafer in addition to the irradiation amount at the irradiation position.

3. A processing apparatus including a chuck table that holds a wafer, and an irradiation unit that irradiates an etching gas that has been converted into plasma to etch the wafer held on the chuck table, a horizontal movement mechanism that moves the chuck table and the irradiation unit relatively in a horizontal direction; a calculation unit that calculates an etching amount of the wafer at the irradiation position of the irradiation unit by the horizontal movement mechanism based on a difference between a previously acquired thickness distribution over the entire surface of the wafer and a previously set finishing thickness distribution; a control unit that controls the etching amount to be the amount calculated by the calculation unit.

4. the calculation unit calculates the irradiation position of the irradiation unit with respect to the wafer in the horizontal direction and the irradiation amount of the etching gas at the irradiation position; 4. The processing device according to claim 3, wherein the control unit controls the moving speed of the horizontal moving mechanism.

5. a lifting mechanism that lifts and lowers the chuck table and the irradiation unit relatively in a vertical direction; The calculation unit calculates the irradiation amount at the irradiation position as well as the height of the irradiation portion relative to the wafer; The processing apparatus according to claim 3 , wherein the control unit controls the lifting mechanism.

6. a flow rate adjusting unit that adjusts the amount of irradiation of the etching gas irradiated from the irradiation unit; the calculation unit calculates the irradiation position of the irradiation unit with respect to the wafer in the horizontal direction and the irradiation amount of the etching gas at the irradiation position; The processing apparatus according to claim 3 , wherein the control unit controls the flow rate adjustment unit.

7. a high-frequency power adjusting unit that adjusts the amount of irradiation of the etching gas irradiated from the irradiation unit; the calculation unit calculates the irradiation position of the irradiation unit with respect to the wafer in the horizontal direction and the irradiation amount of the etching gas at the irradiation position; The processing device according to claim 3 , wherein the control unit controls the high frequency power adjustment unit.

8. a thickness measuring device for measuring the thickness of the wafer held on the chuck table; 4. The processing apparatus according to claim 3, further comprising a memory unit for acquiring the thickness distribution over the entire surface of the wafer measured by the thickness measuring device.

9. 4. The processing apparatus according to claim 3, wherein the irradiation unit comprises an irradiation port for irradiating the etching gas, and a suction port formed around the irradiation port.

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