JP2005251799A - Flattening device of upper face of bump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely and sufficiently perform the flattening work of the upper face of a bump with high throughput without depending on polishing. <P>SOLUTION: A Y-axis movable carriage 14 is installed on a substrate 11 so that it can move in a Y-axis direction. A rotary table device 20 is disposed on the Y-axis movable carriage 14. A chuck 60 holding a silicon wafer W is fitted to the rotary table device 20. The upper face of the bump is machined by a fly cutter device 90 fitted to a Z-axis movable carriage 73. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bump upper surface flattening apparatus, and more particularly to a bump upper surface flattening apparatus that flattens the upper surface of an Au bump formed on the surface of a silicon wafer by plating.

  As a flip chip for bump connection, the development of a flip chip that uses an Au bump formed by plating on the surface of a silicon wafer before dicing and mounts a chip-on-chip or the like by joining the Au bumps is underway.

  In the case of such bump-connected flip chips, in order to reduce bonding stress and improve bonding reliability, it is indispensable to have a technology that flattens the bump upper surface in consideration of bump height alignment and improved surface roughness of the bump upper surface. It is.

  As a technique for planarizing the surface of a silicon wafer during a device manufacturing process, a technique based on a polishing method represented by CMP (Chemical Mechanical Polishing) is known (for example, Patent Documents 1 and 2).

However, the flattening technique by CMP can be applied to the flattening process of the upper surface of the bump, but since it is polishing, the throughput is poor and the flattening takes time. Further, since a slurry containing an abrasive is used, it is not good for the environment, and a cleaning process is essential as a post-treatment, and it is difficult to completely remove the fine abrasive. If the abrasive remains in the silicon wafer, it causes a decrease in the mechanical strength of the bump connection and a decrease in the electrical reliability.
JP-A 64-11754 Japanese Patent Application Laid-Open No. 7-100737

  The problem to be solved by the present invention is to satisfactorily perform the flattening process of the bump upper surface with high accuracy and high accuracy without using polishing.

  A bump upper surface flattening apparatus according to the present invention is a bump upper surface flattening apparatus that flattens an upper surface of a bump formed on a silicon wafer by cutting, in a horizontal axis direction on a base and the base. A horizontally movable table provided movably, a first axis feeding means for reciprocatingly driving the horizontal movable table in a horizontal axis direction, a rotary table provided on the horizontal movable table, and rotating the rotary table A rotation driving means, a workpiece fixing means for detachably fixing a silicon wafer as a workpiece provided on the rotary table, a column fixedly arranged on the base, and the column A vertical moving table provided on the column so as to be movable in the vertical axis direction; a second axis feeding means for reciprocatingly driving the vertical moving table in the vertical axis direction; and a flyer attached to the vertical moving table. And a data device.

  In the bump upper surface flattening apparatus according to the present invention, preferably, the bearing of the rotary table is constituted by an air bearing.

  The bump upper surface flattening apparatus according to the present invention preferably has a static eliminator for removing static electricity from the cutting area by the fly cutter apparatus.

  The bump top surface flattening apparatus according to the present invention is a vertical moving table that is fixed by a second axis feeding means in a state in which a silicon wafer is fixed on a rotary table by a workpiece fixing means and the rotary table is rotationally driven by a rotary driving means. Is moved in the vertical axis direction to position the fly cutter device attached to the vertical movement table in the cutting direction to set the cutting amount, and the first axis feed means moves the horizontal movement table in the horizontal axis direction. Then, cutting feed is performed, and the bump upper surface of the silicon wafer fixed on the rotary table by the workpiece fixing means is cut (turned) by the fly cutter device, and the height of the bump upper surface is made uniform.

  In the bump upper surface flattening apparatus according to the present invention, since the flattening process for aligning the height of the bump upper surface is performed by turning with the fly cutter apparatus as described above, the throughput is better than the flattening process by polishing such as CMP. Since the slurry containing the abrasive is not used, the environment is good, and the problem that the abrasive remains on the silicon wafer can be solved.

  One embodiment of a bump upper surface flattening apparatus according to the present invention will be described with reference to FIGS.

  A bump upper surface flattening apparatus according to one embodiment includes a base 11 having a highly rigid structure fixedly arranged on a floor.

  Two V-shaped guide rails 12 and 13 are formed on the upper surface of the base 11 in parallel to the horizontal axis direction, that is, the Y-axis direction. The V-shaped guide rails 12 and 13 are engaged with inverted V-shaped grooves 15 and 16 formed on the lower bottom surface of the Y-axis moving table 14 which is a horizontal moving table. That is, the Y-axis moving base 14 is guided by the V-shaped guide rails 12 and 13 and can move linearly in the Y-axis direction.

  The guide of the Y-axis moving table 14 by the V-shaped guide rails 12 and 13 is fluid lubrication, and lubricating oil is applied to the gap between the V-shaped guide rails 12 and 13 and the inverted V-shaped groove portions 15 and 16 of the Y-axis moving table 14. It is a VV dynamic pressure guide that enters and handles the load of the Y-axis moving table 14 with hydraulic pressure.

  The axis movement of the Y axis moving table 14 in the Y axis direction is performed by a ball screw 18 that is rotationally driven by a Y axis servo motor 17 (see FIG. 6) (first axis feeding means). A rotary encoder 19 (see FIG. 6) is attached to the Y-axis servomotor 17 as a Y-axis position detector. The rotary encoder 19 is position detection means for detecting the movement position in the horizontal axis direction (Y-axis direction) of the Y-axis movement table 14 that is a horizontal movement table.

  A rotary table device 20 is mounted on the Y-axis moving table 14. As shown in detail in FIG. 4, the rotary table device 20 includes a ring-shaped base member 21 fixed to the upper surface of the Y-axis moving table 14, a horizontal adjuster 22, and mounting bolts 23 as fixed side members. A flanged cylindrical bearing support member 24 mounted horizontally on the member 21, and a ring-shaped upper bearing member 25 and a lower bearing member 26 mounted concentrically on the upper and lower sides of the bearing support member 24. Have.

  A central shaft portion 28 of a rotary table 27 is rotatably engaged with the upper bearing member 25 and the lower bearing member 26. A lower flange member 29 is fixed to the lower end of the central shaft portion 28 by a bolt 30.

  The upper bearing member 25 constitutes an upper thrust air bearing 32 and a radial air bearing 33, and the lower bearing member 26 constitutes a lower thrust air bearing 34 and a radial air bearing 35. Accordingly, the upper bearing member 25 and the lower bearing member 26 perform both the thrust direction and radial direction bearings of the rotary table 27 by the hydrostatic air bearing.

  In the bearing support member 24, air pressure supply passages 36 and 37 for supplying air pressure to the air bearings 32 to 35 are formed, and an air bearing pipe 38 is formed.

  A C-axis motor 40, which is a rotation driving means for rotating the rotary table 27, is attached to the lower portion of the bearing support member 24. The C-axis motor 40 includes a motor case 42 fixedly connected to a lower portion of the bearing support member 24 by bolts 41, a stator member 43 fixed in the motor case 42, and a lower flange member 29 of the rotary table 27 by bolts 44. The rotor 45 is fixedly connected.

  A main shaft rotary encoder 46 is attached to the lower portion of the motor case 42. The rotary encoder 46 includes an encoder case 48 fixedly connected to the lower portion of the motor case 42 by bolts 47, a fixed side member 49 fixedly arranged in the encoder case 48, and a rotation attached to the extension shaft portion 50 of the rotor 45. The rotation speed (rotation speed) of the C-axis motor 40 is detected.

  On the rotary table 27, a disk-like vacuum suction chuck 60 is attached as a workpiece fixing means. The vacuum chucking chuck 60 has a well-known structure, and detachably fixes a silicon wafer W as a workpiece on the upper surface. As shown in FIG. 7, the silicon wafer W has a plating resist layer Wa and an Au bump Wb formed by plating on the upper surface.

  A shaft-like vacuum pressure supply member 63 having a vacuum pressure supply passage 62 for supplying a vacuum pressure to the vacuum suction chuck 60 is attached to the center of the rotary table 27. The vacuum pressure supply member 63 passes through the C-axis motor 40 and the rotary encoder 46 in the axial direction, and a rotary joint 64 for supplying vacuum pressure is attached to the lower end portion.

  Referring to FIGS. 1 and 2, a column 71 is vertically attached to one end side of the base 11 in the Y-axis direction. On the front vertical surface of the column 71, a linear guide 72 in the vertical axis direction, that is, the Z-axis direction is provided. A Z-axis moving table (saddle) 73, which is a vertical moving table, is attached to the linear guide 72. The Z-axis moving table 73 is guided by the linear guide 72 and can move in the Z-axis direction.

  The axial movement of the Z-axis moving base 73 in the Z-axis direction is performed by a ball screw 75 that is rotationally driven by a Z-axis servo motor 74 (second axial feed means). A rotary encoder 76 is attached to the Z-axis servomotor 74 as a Z-axis position detector.

  Note that the linear guide 72 and the ball screws 18 and 75 are preferably lubricated with low dust generation grease.

  A fly cutter device 90 is attached to the front portion of the Z-axis moving table 73 downward by an attachment member 77. 2, illustration of the attachment member 77 and the fly cutter device 90 is omitted.

  As shown in detail in FIG. 5, the fly cutter device 90 includes a housing 91, a distal end member 95 attached to the distal end portion (lower end portion) of the housing 91 via a spacer 94, and the housing 91 and the distal end member 95. A tool rotation shaft 97 rotatably supported by air bearings 92, 93, 96, a tool support 98 attached to the tip of the tool rotation shaft 97 by a bolt 107, and a tool tool attached to the tool support 98 99. In this embodiment, two tool tools 99 are attached to the tool support 98, but one tool tool 99 may be provided.

  The cutting tool 99 is a diamond cutting tool in which a blade 101 made of single crystal or polycrystalline diamond is attached to the tip of the shank 100.

  A tool rotating electric motor 102 is attached to the upper end of the housing 91. The tool rotating electric motor 102 includes a motor housing 103 fixed to the upper end portion of the housing 91, a stator member 104 attached to the motor housing 103, and a rotor shaft 105 fixedly connected to the upper end portion of the tool rotating shaft 97. And the rotor 106 attached to the rotor shaft 105, and rotationally drives the tool rotation shaft 97. The tool rotating electric motor 102 has a so-called built-in motor structure.

  As shown in FIG. 1, a static eliminator 81 is attached to the Z-axis moving table 73 to remove static electricity from the cutting region by the fly cutter device 90. The static eliminator 81 is a well-known device called an ionizer, which generates equal amounts of positive and negative air ions, and contacts charged ions with ions of opposite polarity, thereby reducing the charged potential of the charged materials, The electric field is balanced at a low potential so that the same amount of positive and negative ions are in contact with the charged object. The static eliminator 81 may be arranged on the left side (front side) of the fly cutter device 90 in FIG.

  One embodiment of the control system of the bump upper surface flattening apparatus according to the present invention will be described with reference to FIG. This control system is a microcomputer-type servo controller 150, and includes a Y-axis controller 151, a Z-axis controller 152, and a C-axis controller 153. The servo control device 150 serves as table rotation speed control means for variably controlling the rotation speed of the rotation table 27.

  The Y-axis controller 151 moves the Y-axis by the Y-axis servomotor 17 so that there is no deviation between the feed speed command value and the differential value (speed) of the Y-axis servomotor position detected by the Y-axis rotary encoder 19. The speed control of the base 14 in the Y-axis direction is performed.

  The Z-axis control unit 152 eliminates the deviation between the Z-axis command value for commanding the Z-axis coordinate position of the Z-axis moving base 73 and the Z-axis servo motor position detected by the Z-axis rotary encoder 76. The Z-axis coordinate position of the Z-axis moving table 73 is controlled by the servo motor 74.

  The C-axis control unit 153 gives a rotation speed command for the rotation table 27 and rotates the rotation table 27 using the rotation speed of the rotation table 27 calculated by the C-axis servo motor position detected by the C-axis rotary encoder 46. Feedback control of speed.

  It should be noted that the detection of the Y-axis coordinate position of the Y-axis moving base 14 is performed with high accuracy using a linear scale provided in the Y-axis direction, regardless of the Y-axis servo motor position detected by the Y-axis rotary encoder 19. Can also be detected.

  Next, the operation of the bump upper surface flattening apparatus having the above-described configuration will be described.

  First, the silicon wafer W as a workpiece is fixed on the rotary table 27 by the vacuum suction chuck 60. This fixing is performed by positioning so that the rotation center of the rotary table 27 and the center of the silicon wafer W coincide.

  After fixing the silicon wafer W, the rotary table 27 is rotationally driven by the C-axis motor 40, and in this state, the Z-axis moving table 73 is moved in the Z-axis direction by the Z-axis servo motor 74. Thus, the fly cutter device 90 attached to the Z-axis moving table 73 is positioned in the cutting direction to set the cutting amount.

  The rotation of the rotary table 27 by the C-axis motor 40 is satisfactorily performed with low dust generation in an oil-less bearing state by the air bearings 32 to 35. Low dust generation enables processing in a clean room.

  This cutting amount setting is performed by setting the Z-axis control unit to zero the deviation between the Z-axis command value for commanding the Z-axis coordinate position of the Z-axis moving table 73 and the Z-axis servo motor position detected by the Z-axis rotary encoder 76. The feedback control by 152 is performed with high accuracy.

  Then, the tool rotating shaft 97 of the fly cutter device 90 is rotationally driven by the tool rotating electric motor 102, and the tool tool 99 is rotated around the rotation center axis of the tool rotating shaft 97, and the Y-axis servomotor 17 performs Y rotation. Cutting feed is performed by moving the axis moving table 14 in the Y-axis direction. As a result, the upper surface of the Au bump Wb of the silicon wafer W fixed on the rotary table 27 by the vacuum suction chuck 60 is turned by the bite tool 99 as shown in FIG. Align.

  The cutting feed of the Y-axis moving table 14 is performed by the Y-axis control unit 151 that makes the deviation between the feed speed command value and the differential value (speed) of the Y-axis servo motor position detected by the Y-axis rotary encoder 19 zero. Highly accurate by feedback control.

  In the bump upper surface flattening apparatus according to the present invention, since the flattening process for aligning the height of the bump upper surface is performed by the turning by the fly cutter apparatus 90 as described above, the throughput is higher than that of the flattening process by polishing such as CMP. Since the slurry containing the abrasive is not used well, it is good for the environment, and the problem that the abrasive remains on the silicon wafer W can be solved.

  In addition, since the turning is performed by the fly cutter device 90 having the blade portion 101 made of single crystal or polycrystalline diamond, a flattening process for aligning the height of the bump upper surface without causing a reduction in processing accuracy due to wear on the tool side is performed. Performed with high accuracy.

  Further, since the static eliminator 81 removes static electricity in the cutting region by the fly cutter device 90, the charging phenomenon due to static electricity of the cutting dust scattered in the cutting region can be eliminated.

  As a result, it becomes difficult for the cutting chips due to static electricity to adhere to surrounding members, apparatus wall surfaces, and the like constituting the cutting region, and an effect of preventing the processed surface from being stained is obtained.

  In addition, since cutting dust can be prevented from adhering in the cutting region, there is no adhesion and solidification phenomenon of cutting waste, and the adhering and solidifying cutting dust falls into the apparatus and contaminates the rotary table 27 and the vacuum suction chuck 60. It is possible to solve the problem that the adhered and solidified cutting waste falls on the silicon wafer W being cut and adversely affects the processing.

It is a side view which shows one Embodiment of the bump upper surface planarization processing apparatus by this invention. It is a top view which shows one Embodiment of the bump upper surface planarization processing apparatus by this invention. It is a front view which shows one Embodiment of the bump upper surface planarization processing apparatus by this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the rotary table apparatus used for the bump upper surface planarization processing apparatus by this invention. It is a perspective view which shows the principal part of one Embodiment of the fly cutter apparatus used for the bump upper surface planarization processing apparatus by this invention. It is a block diagram which shows one Embodiment of the control system of the bump upper surface planarization processing apparatus by this invention. It is explanatory drawing which shows typically an example of the turning state by the bump upper surface planarization processing apparatus by this invention.

Explanation of symbols

11 base 14 Y-axis moving table (horizontal moving table)
17 Y-axis servo motor 18 Ball screw 19 Rotary encoder (position detection means)
DESCRIPTION OF SYMBOLS 20 Rotary table apparatus 21 Base member 27 Rotary table 32 Thrust air bearing 33 Radial air bearing 34 Thrust air bearing 35 Radial air bearing 40 C-axis motor (rotation drive means)
46 Rotary encoder 60 Vacuum chuck (workpiece fixing means)
71 Column 73 Z-axis moving table (vertical moving table)
74 Z-axis servo motor 75 Ball screw 76 Rotary encoder 81 Static eliminator 90 Fly cutter device 97 Tool rotation shaft 99 Tool tool 100 Shank 101 Blade portion 102 Electric motor for tool rotation 150 Servo control device 151 Y-axis control portion 152 Z-axis control portion 153 C-axis control part W Silicon wafer Wb Au bump

Claims (3)

A bump upper surface flattening apparatus for flattening the upper surface of a bump formed on a silicon wafer by cutting,
The base,
A horizontal moving table provided on the base so as to be movable in the horizontal axis direction;
First axis feeding means for reciprocally driving the horizontal moving table in the horizontal axis direction;
A rotary table provided on the horizontal moving table;
Rotation driving means for rotating the rotation table;
A workpiece fixing means for detachably fixing a silicon wafer, which is a workpiece, provided on the rotary table, on the rotary table;
A column fixedly disposed on the base;
A vertical moving table provided on the column so as to be movable in the vertical axis direction;
Second axis feeding means for reciprocatingly driving the vertical moving table in the vertical axis direction;
A fly cutter device attached to the vertical moving table;
A bump upper surface flattening processing apparatus having:   The bump upper surface flattening apparatus according to claim 1, wherein the bearing of the rotary table is constituted by an air bearing. The bump upper surface flattening apparatus according to claim 1, further comprising a static eliminator that removes static electricity in a cutting area by the fly cutter apparatus.

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