JP2014065088A - Polishing device - Google Patents

Abstract

A polishing apparatus capable of suppressing a decrease in thickness accuracy of polishing processing is provided.
A polishing apparatus comprising: a chuck table 20 that holds a workpiece; and a polishing means that includes a polishing pad that polishes the workpiece held on the chuck table. A holding table 22 having a holding surface 21 for holding an object, and a support member 23 for supporting the holding table. The support members are arranged concentrically and have radial positions from the central axis C of the concentric circles. A plurality of different tubular fluid passages 25a, 25b, 25c, and 25d are provided, a fluid controlled to a desired temperature is supplied to each tubular fluid passage, and the temperature distribution of the holding surface of the holding table can be controlled. Fluid supply means 70 is provided.
[Selection] Figure 3

Description

  The present invention relates to a polishing apparatus for polishing a workpiece.

  In the semiconductor device manufacturing process, lattice-shaped division planned lines called streets are formed on the surface of a wafer made of silicon or a compound semiconductor. Then, a device such as an IC or LSI is formed in each area partitioned by the division lines. These wafers are ground and / or polished to reduce the thickness to a predetermined thickness, and then cut along the streets with a cutting machine and divided into individual chips to manufacture semiconductor devices. . In order to reduce the size and weight of a device, the semiconductor wafer is usually ground to the predetermined thickness by grinding the backside of the semiconductor wafer prior to cutting the semiconductor wafer along the street and dividing it into individual devices. ing. The grinding of the back surface of a semiconductor wafer is usually performed by pressing a grinding wheel formed by fixing diamond abrasive grains with an appropriate bond such as a resin bond against the back surface of the semiconductor wafer while rotating at high speed. When the back surface of the semiconductor wafer is ground by such a grinding method, a so-called processing strain is generated on the back surface of the semiconductor wafer, which causes a problem that the bending strength of the individually divided devices is lowered.

  In order to solve the above-described problems, a polishing apparatus that removes grinding distortion by performing CMP polishing on the back surface of a semiconductor wafer that has been subjected to grinding with a polishing pad mixed with abrasive grains and a polishing liquid is disclosed in Patent Document 1 below. ing.

JP 2011-206881 A

  However, it is difficult to polish the entire surface uniformly by polishing, and when the back surface of a workpiece such as a wafer is polished, the outer peripheral edge is easily processed. There is a problem that it becomes thinner than the central portion and the thickness accuracy deteriorates. Moreover, since the heat | fever by friction accumulates, a center part may become thin compared with an outer peripheral part.

  An object of the present invention is to provide a polishing apparatus that can suppress a decrease in thickness accuracy of polishing processing.

  A polishing apparatus according to the present invention is a polishing apparatus including a chuck table that holds a workpiece, and a polishing unit that includes a polishing pad that polishes the workpiece held on the chuck table. Comprises a holding table having a holding surface for holding a workpiece and a support member for supporting the holding table, the support member being arranged concentrically and radially from the central axis of the concentric circle A plurality of tubular fluid passages having different positions are provided, a fluid controlled to a desired temperature is supplied to each tubular fluid passage, and the temperature distribution of the holding surface of the holding table can be controlled. It has the means, It is characterized by the above-mentioned.

  A polishing apparatus according to the present invention is a polishing apparatus including a chuck table and a polishing unit, and the chuck table includes a holding table having a holding surface that holds a workpiece, and a support member that supports the holding table. The support member is provided with a plurality of tubular fluid passages arranged concentrically and having different radial positions from the central axis of the concentric circles, and each tubular fluid passage is controlled to a desired temperature. And a control fluid supply means capable of supplying the fluid and controlling the temperature distribution on the holding surface of the holding table. According to the polishing apparatus of the present invention, it is possible to control the temperature distribution of the holding surface, and it is possible to suppress the decrease in the thickness accuracy of the polishing process.

FIG. 1 is a perspective view showing a polishing apparatus according to an embodiment. FIG. 2 is a perspective view illustrating a part of the polishing apparatus according to the embodiment. FIG. 3 is a cross-sectional view showing a main part of the polishing apparatus according to the embodiment. FIG. 4 is a top view of the support member according to the embodiment.

  Hereinafter, a polishing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment]
The embodiment will be described with reference to FIGS. 1 to 4. The present embodiment relates to a polishing apparatus. FIG. 1 is a perspective view showing a polishing apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing a part of the polishing apparatus according to the embodiment, and FIG. 3 shows a main part of the polishing apparatus according to the embodiment. FIG. 4 is a top view of the support member according to the embodiment.

  The polishing apparatus 1 according to this embodiment includes a chuck table 20, a polishing unit 60, a horizontal moving unit 40 (see FIG. 2), a vertical moving unit 50, a control fluid supply unit 70 (see FIG. 3), and a control. Part 100.

  The chuck table 20 holds the workpiece W. The chuck table 20 includes a holding table 22 having a holding surface 21 that holds the workpiece W. The workpiece W is, for example, a semiconductor wafer or an optical device wafer made of silicon or a compound semiconductor. On the surface of the workpiece W, grid-like division planned lines are formed, and devices such as ICs and LSIs are formed in each area partitioned by the division planned lines. Workpiece W is a holding surface in a state where it is mounted on a support base, a state where a protective tape is attached to the back surface, or a state where it is mounted on an annular frame via an adhesive tape. 21 is mounted.

  The chuck table 20 is driven by a rotational drive source (not shown) and rotates around the Z axis. The Z-axis direction of this embodiment is a vertical direction.

  The polishing means 60 includes a polishing pad 61, a spindle housing 62, a rotating spindle 63, and a wheel mount 64. The rotary spindle 63 is rotatably supported by the spindle housing 62. The rotary spindle 63 is driven to rotate by a rotary drive source (not shown) connected to the spindle housing 62 and rotates around the Z axis.

  A wheel mount 64 is connected to the tip of the rotary spindle 63. The polishing pad 61 is fixed to the wheel mount 64 with bolts or the like. The polishing pad 61 is for polishing the workpiece W held on the chuck table 20. The polishing pad 61 has a polishing portion on the surface (lower surface) facing the workpiece W. For example, the polishing part is obtained by dispersing and impregnating a felt material with a large number of abrasive grains such as diamond abrasive grains.

  As shown in FIG. 2, the horizontal moving means 40 includes a pair of guide rails 41, a slide member 42, a ball screw 43, and a pulse motor 44. The guide rail 41 extends in the X-axis direction and guides the movement of the slide member 42 in the X-axis direction. The X-axis direction is orthogonal to the Z-axis direction. The chuck table 20 is connected to the slide member 42 and moves together with the slide member 42 in the X-axis direction. The ball screw 43 is screwed into a screw hole formed in the slide member 42. The pulse motor 44 is connected to the ball screw 43 and moves the slide member 42 in the X-axis direction by rotating the ball screw 43.

  Returning to FIG. 1, the vertical moving means 50 moves the polishing means 60 in the Z-axis direction. The vertical moving means 50 includes a ball screw 51, a pulse motor 52, a pair of guide rails 53, and a slide member 54. The guide rail 53 extends in the Z-axis direction and guides the movement of the slide member 54 in the Z-axis direction. The spindle housing 62 is connected to the slide member 54 and moves in the Z-axis direction together with the slide member 54. The ball screw 51 is screwed into a screw hole formed in the slide member 54. The pulse motor 52 is connected to the ball screw 51 and rotates the ball screw 51 to move the slide member 54 in the Z-axis direction.

  In the polishing apparatus 1, the chuck table 20 is positioned below the polishing pad 61 by the horizontal movement unit 40, and the workpiece W held on the chuck table 20 is polished by the polishing unit 60. Specifically, the polishing apparatus 1 rotates the chuck table 20 around the Z axis, rotates the polishing pad 61, and presses the polishing pad 61 against the workpiece W by the vertical movement unit 50. The polishing apparatus 1 of this embodiment polishes the workpiece W by chemical mechanical polishing, so-called CMP (Chemical Mechanical Polishing). The polishing apparatus 1 supplies the polishing liquid between the polishing pad 61 and the workpiece W, and rotates the polishing pad 61 and the workpiece W to slide relative to each other to rotate the workpiece W. To polish.

  The polishing apparatus 1 of the present embodiment includes cassettes 71 and 72 for storing the workpiece W, carry-in / out means 73, alignment means 74, carry-in means 75, carry-out means 76, and cleaning means 77. The unloading / unloading means 73 unloads the workpiece W before polishing from the cassette 71 and loads the polished workpiece W into the cassette 72. The alignment means 74 aligns the center position of the workpiece W. The carrying-in means 75 carries the workpiece W before polishing into the chuck table 20 and places it thereon. The unloading means 76 unloads the polished workpiece W from the chuck table 20 to the cleaning means 77. The cleaning means 77 cleans the workpiece W after polishing.

  Here, when the workpiece W is polished by the polishing means 60, it is difficult to uniformly polish the entire surface of the workpiece W. When the back surface of the workpiece W is polished, the outer peripheral edge of the workpiece W is easily processed. For this reason, compared with the center part of the to-be-processed object W, the grinding | polishing amount of an outer peripheral part increases, and there exists a problem that an outer peripheral part becomes thinner than a central part and thickness accuracy falls. Moreover, since the heat | fever by grinding | polishing accumulates, a center part may become thin compared with an outer peripheral part. When the temperature of the central portion of the workpiece W becomes higher than the temperature of the outer peripheral portion due to the heat generated in the polishing process, the chemical reaction in the central portion is promoted, and the amount of polishing in the central portion increases.

  The polishing apparatus 1 according to the present embodiment has a configuration capable of controlling the temperature distribution of the holding surface 21 of the holding table 22. Thereby, it can suppress that the grinding | polishing with respect to the to-be-processed object W becomes non-uniform | heterogenous, and can suppress the fall of the thickness precision of grinding | polishing processing.

  As shown in FIG. 3, the chuck table 20 includes a holding table 22 and a support member 23. The holding table 22 has a disk shape and has a holding surface 21. The suction part 22a which is a part constituting the holding surface 21 is made of, for example, porous ceramic. The suction part 22a has a disk shape. The suction portion 22a is provided from the holding surface 21 to a predetermined depth on the back surface 22b side. The back surface 22 b is a surface opposite to the holding surface 21 side in the holding table 22.

  The support member 23 supports the holding table 22. The holding table 22 is placed on the support member 23 with the back surface 22b facing the upper surface 23a of the support member 23. The holding table 22 is fixed to the support member 23 with bolts 5. The holding table 22 and the support member 23 are formed with suction passages 24 communicating with each other. The suction passage 24 is provided in the shaft core portion of the holding table 22 and the support member 23 and extends in the Z-axis direction. The suction passage 24 is connected to a vacuum suction source (not shown). The suction part 22 a is connected to a vacuum suction source via the suction passage 24. The chuck table 20 sucks and holds the workpiece W placed on the holding surface 21 by a negative pressure supplied from a vacuum suction source.

  The support member 23 is a columnar or disk-shaped member. The outermost diameter of the support member 23 and the outermost diameter of the holding table 22 are equal. The upper surface 23a of the support member 23 and the back surface 22b of the holding table 22 are horizontal surfaces and are in contact with each other. As shown in FIGS. 3 and 4, the support member 23 has a plurality of tubular fluid passages 25 (25 a, 25 b) arranged concentrically and having different radial positions from the center (center axis) C of the concentric circles. 25c, 25d). In the present embodiment, the support member 23 is formed with four tubular fluid passages, a first tubular fluid passage 25a, a second tubular fluid passage 25b, a third tubular fluid passage 25c, and a fourth tubular fluid passage 25d.

  The tubular fluid passages 25 a, 25 b, 25 c and 25 d are grooves formed on the upper surface 23 a of the support member 23. The tubular fluid passages 25a, 25b, 25c, and 25d are circular when viewed from above, and are arranged concentrically with a common central axis C. The central axis C coincides with the central axis of the support member 23. In the present specification, the “radial direction” indicates a direction centered on the central axis C and orthogonal to the central axis C. The “axial direction” indicates a direction parallel to the central axis C.

  As shown in FIG. 3, the tubular fluid passages 25a, 25b, 25c, and 25d of this embodiment have a rectangular cross section (including a square). In the present embodiment, the tubular fluid passages 25a, 25b, 25c, 25d have the same radial width and the same depth. The first tubular fluid passage 25a is disposed on the innermost side in the radial direction. The second tubular fluid passage 25b is disposed radially outside the first tubular fluid passage 25a and radially inside the third tubular fluid passage 25c. The third tubular fluid passage 25c is arranged on the inner side in the radial direction than the fourth tubular fluid passage 25d.

  The tubular fluid passages 25a, 25b, 25c, and 25d are arranged at predetermined intervals in the radial direction. The tubular fluid passages 25a, 25b, 25c, and 25d can be arranged at regular intervals in the radial direction, for example. The radial distance r from the central axis C to the tubular fluid passages 25a, 25b, 25c, 25d is the distance between the central axis C and the center line in the width direction of each tubular fluid passage 25a, 25b, 25c, 25d. For example, the radial distance r from the central axis C to the first tubular fluid passage 25a is the distance between the central axis C and the center line L in the width direction of the first tubular fluid passage 25a.

  In the present embodiment, the tubular fluid passages 25a, 25b, 25c, and 25d are arranged at equal intervals in the radial direction, and the difference Δr12 in the radial distance r between the first tubular fluid passage 25a and the second tubular fluid passage 25b is The difference Δr23 in the radial distance r between the second tubular fluid passage 25b and the third tubular fluid passage 25c is equal to the difference Δr34 in the radial distance r between the third tubular fluid passage 25c and the fourth tubular fluid passage 25d. .

  As shown in FIG. 3, when the holding table 22 is attached to the support member 23, the back surface 22b of the holding table 22 closes the upper portions of the tubular fluid passages 25a, 25b, 25c, and 25d. A supply passage 26 (26a, 26b, 26c, 26d) and a discharge passage 27 (27a, 27b, 27c, 27d) are connected to the tubular fluid passages 25a, 25b, 25c, 25d, respectively. A first supply passage 26a and a first discharge passage 27a are connected to the first tubular fluid passage 25a. Similarly, a second supply passage 26b and a second discharge passage 27b are provided in the second tubular fluid passage 25b, and a third supply passage 26c and a third discharge passage 27c are provided in the fourth tubular fluid passage 25c. A fourth supply passage 26d and a fourth discharge passage 27d are connected to the passage 25d.

  The supply passages 26a, 26b, 26c, and 26d are passages that supply fluid to the tubular fluid passages 25a, 25b, 25c, and 25d. The fluid supplied to the tubular fluid passages 25a, 25b, 25c, and 25d is, for example, water. The discharge passages 27a, 27b, 27c, and 27d are passages that discharge fluid from the tubular fluid passages 25a, 25b, 25c, and 25d. As shown in FIG. 4, the supply passages 26a, 26b, 26c, and 26d and the discharge passages 27a, 27b, 27c, and 27d are disposed at symmetrical positions with the central axis C therebetween. Therefore, the fluid (see arrow Y1) that has flowed into the tubular fluid passages 25a, 25b, 25c, and 25d from the supply passages 26a, 26b, 26c, and 26d flows halfway through the tubular fluid passages 25a, 25b, 25c, and 25d, and the arrow Y2 As shown in FIG. 4, the gas is discharged from the discharge passages 27a, 27b, 27c, and 27d.

  The control fluid supply means 70 of this embodiment includes supply passages 26a, 26b, 26c, and 26d, discharge passages 27a, 27b, 27c, and 27d, control valves 71, 72, 73, and 74, and a fluid supply device 75.

  The fluid supply device 75 is connected to the supply passages 26a, 26b, 26c, and 26d and the discharge passages 27a, 27b, 27c, and 27d, respectively. The fluid supply device 75 includes, for example, a pump and a temperature control unit. The fluid supply device 75 can independently control the temperature of the fluid supplied to each of the supply passages 26a, 26b, 26c, and 26d by the temperature control means. That is, the fluid supply device 75 can control the temperature of the fluid supplied to the first supply passage 26a to an arbitrary temperature regardless of the temperature of the fluid supplied to the other supply passages 26b, 26c, and 26d. The fluid supply device 75 can similarly control the temperature of the fluid supplied to the second supply passage 26b, the third supply passage 26c, and the fourth supply passage 26d to an arbitrary temperature. The fluid supply device 75 includes, for example, a high-temperature fluid supply source and a low-temperature fluid supply source, and mixes the high-temperature fluid and the low-temperature fluid to change the temperature of the supplied fluid to a desired temperature. can do.

  In addition, the fluid supply device 75 sends the fluid controlled to a desired temperature to the supply passages 26a, 26b, 26c, and 26d by a pump. A first control valve 71 is provided in the first supply passage 26a. The second supply passage 26b is provided with a second control valve 72, the third supply passage 26c is provided with a third control valve 73, and the fourth supply passage 26d is provided with a fourth control valve 74. The control valves 71, 72, 73, and 74 can open and close the supply passages 26a, 26b, 26c, and 26d. The control valves 71, 72, 73, 74 of the present embodiment can freely control the opening degree. That is, the control fluid supply means 70 can control the temperature and flow rate of the fluid supplied to the supply passages 26a, 26b, 26c, and 26d. The fluid supply device 75 and the control valves 71, 72, 73, 74 are controlled by the control unit 100.

  The control fluid supply means 70 can supply the fluid controlled to a desired temperature for each tubular fluid passage 25a, 25b, 25c, 25d, and can control the temperature distribution of the holding surface 21 of the holding table 22. In the following description, the temperature of the fluid supplied to the first tubular fluid passage 25a is the first supply temperature T1, the temperature of the fluid supplied to the second tubular fluid passage 25b is the second supply temperature T2, and the third tubular fluid passage 25c. The temperature of the fluid to be supplied is referred to as a third supply temperature T3, and the temperature of the fluid to be supplied to the fourth tubular fluid passage 25d is referred to as a fourth supply temperature T4.

  For example, when polishing the workpiece W whose outer peripheral edge is easily processed, the control fluid supply unit 70 sets the temperature of the outer peripheral portion relatively lower than the temperature of the central portion on the holding surface 21 of the holding table 22. Thus, the temperature of the fluid supplied to each tubular fluid passage 25a, 25b, 25c, 25d is controlled. As an example, the control fluid supply means 70 controls the fourth supply temperature T4 to be lower than the other supply temperatures T1, T2, T3. The control fluid supply means 70 may control the supply temperatures T1, T2, T3, and T4 so that the temperature of the holding surface 21 decreases from the central portion of the holding table 22 toward the outer peripheral portion.

  When the central portion of the workpiece W is more easily processed than the outer peripheral portion, the control fluid supply means 70 is configured so that the temperature of the central portion of the holding table 22 is relatively lower than the temperature of the outer peripheral portion. The temperature of the fluid supplied to the fluid passages 25a, 25b, 25c, and 25d is controlled. As an example, the control fluid supply means 70 controls the first supply temperature T1 to be lower than the other supply temperatures T2, T3, T4. By flowing cold water (about 23 ° C.) through the first supply passage 26a and the second supply passage 26b near the center, and flowing hot water (about 35 ° C.) through the fourth supply passage 26d and the third supply passage 26c near the outer periphery, The polishing rate can be controlled by the part. The control fluid supply means 70 may control the supply temperatures T1, T2, T3, and T4 so that the temperature of the holding surface 21 decreases as it goes from the outer peripheral portion to the central portion of the holding table 22.

  In the present embodiment, the tubular fluid passages 25a, 25b, 25c, and 25d have the same width and depth, but the present invention is not limited to this. The width or depth of each tubular fluid passage 25a, 25b, 25c, 25d can be arbitrarily determined. Moreover, the cross-sectional shape of the tubular fluid passages 25a, 25b, 25c, and 25d is not limited to a rectangular shape, and may be an arbitrary shape.

  Moreover, although the tubular fluid passages 25a, 25b, 25c, and 25d of the present embodiment are arranged at equal intervals in the radial direction, the present invention is not limited to this, and may be arranged concentrically. For example, the radial position of each tubular fluid passage 25a, 25b, 25c, 25d may be determined according to the diameter of the workpiece W to be processed. That is, when the polishing apparatus 1 is capable of polishing workpieces W of different sizes, the outer peripheral portion of the workpiece W (for example, when the workpiece W of each size is placed on the chuck table 20 (for example, The tubular fluid passages 25a, 25b, 25c, and 25d may be disposed at positions facing the edge of the workpiece W).

  The control fluid supply means 70 can also control the position of the holding surface 21 in the Z-axis direction by controlling the temperature of the fluid supplied to each of the supply passages 26a, 26b, 26c, and 26d. The holding table 22 expands and contracts depending on the temperature of the fluid. Using this expansion and contraction, a part of the holding surface 21 can be raised with respect to the other part, or can be settled with respect to the other part. Further, it is possible to increase the smoothness of the holding surface 21 by utilizing thermal expansion or thermal contraction.

[Modification of Embodiment]
A modification of the embodiment will be described. Even if the thickness of the workpiece W is detected during the polishing process, and the temperature control by the control fluid supply means 70 is started based on the detection result, or the supply temperatures T1, T2, T3, and T4 are changed. Good. The start of the temperature control and the change of the supply temperature may be performed automatically or in accordance with an operator instruction. When detecting the thickness of the workpiece W, for example, the polishing process is temporarily stopped, and the workpiece is detected by a contact or non-contact detection device in a state where the polishing pad 61 is separated from the workpiece W. The distribution of the thickness of W in the radial direction is detected.

  Based on the detection result, the temperature by the control fluid supply means 70 is set so that the portion of the holding surface 21 that holds the relatively thick portion of the workpiece W is relatively hotter than the other portions. Control is executed and corrected. As described above, the temperature control by the control fluid supply unit 70 is executed and corrected based on the actual thickness of the workpiece W, so that the thickness accuracy of the polishing process can be further improved.

  The contents disclosed in the above embodiments and modifications can be executed in appropriate combination.

DESCRIPTION OF SYMBOLS 1 Polishing apparatus 20 Chuck table 21 Holding surface 22 Holding table 23 Support member 25a First tubular fluid passage 25b Second tubular fluid passage 25c Third tubular fluid passage 25d Fourth tubular fluid passage 60 Polishing means 61 Polishing pad 62 Spindle housing 63 Rotation Spindle 64 Wheel mount 70 Control fluid supply means 100 Control unit W Workpiece

Claims (1)

A polishing apparatus comprising: a chuck table for holding a workpiece; and a polishing means having a polishing pad for polishing the workpiece held on the chuck table,
The chuck table includes a holding table having a holding surface that holds a workpiece, and a support member that supports the holding table,
The support member is provided with a plurality of tubular fluid passages arranged concentrically and having different radial positions from the center of the concentric circles,
A polishing apparatus comprising control fluid supply means for supplying a fluid controlled to a desired temperature for each tubular fluid passage and controlling a temperature distribution of the holding surface of the holding table.

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