JP4683849B2 - Processing equipment - Google Patents

Description

  The present invention relates to a processing apparatus, and more particularly to a processing apparatus used for bump upper surface flattening for flattening the upper surface of a bump formed on the surface of a silicon wafer.

  As a flip chip for bump connection, 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 semiconductor 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 planarization technique by CMP can be applied to the planarization of the bump upper surface, but since it is polishing, the throughput is poor and the planarization takes time. Further, in order to use a slurry containing abrasive, not good to the environment, the washing step as a post-treatment is required, it is difficult to completely remove fine abrasive. When the abrasive remains on the silicon wafer, lowering of the mechanical strength of the bump connection, causing deteriorating the electrical reliability.

On the other hand, it is considered that the bump upper surface is planarized without using an abrasive by cutting using a high precision lathe. In such flattening processing, it is required to measure the flatness of the processed surface with high accuracy, to accurately determine whether the flatness is within the required tolerance, and to perform processing with high throughput and high yield. The
JP-A 64-11754 Japanese Patent Application Laid-Open No. 7-100737

  The problem to be solved by the present invention is to efficiently and accurately measure the flatness of a processed surface in a bump upper surface flattening process, etc., and to perform the bump upper surface flattening process with a high throughput and a high yield. It is.

The invention according to claim 1 is a base, and a horizontal moving base provided on the base so as to be movable in the horizontal axis direction and axially fed to a machining work area and a measurement work area which are different in the horizontal axis direction. A first axis feeding means for driving the horizontal movement table in a horizontal axis direction, a rotary table provided on the horizontal movement table, a rotation driving means for rotating the rotation table, and the rotation table. provided, and the workpiece fixing means for detachably fixing the workpiece on the rotary table, and fixedly arranged column on the base, the column, is movable in the vertical direction a vertical movement table, a second shaft feed means for driving the vertical movement table in the vertical direction, is provided in the vertical movement table, cutlery tool for machining of the workpiece in the machining operation region is attached and the base, the measurement work area The have a measuring means to measure the workpiece in position, said measuring means flat Mend measuring means scans the processing surface of the workpiece without contact you measure the flatness of the processed surface And performing the flattening process on the upper surface of the work piece fixed to the rotary table of the horizontal moving table by the tool attached to the tool rest in the processing work area, and then moving the horizontal moving table. wherein and sends the processing work area to the measuring working area, of the flatness measuring means to continue the rotation of the rotary table by the rotation drive means, have a row scanning with respect to the processing surface of the workpiece, the workpiece The workpiece is reciprocated between the machining work area and the measurement work area until the flatness of the machined surface of the object is within the required tolerance, and flattening and flatness measurement are performed. It is configured to It is an engineering equipment.

  In the processing apparatus according to the present invention, the workpiece is fixed on the rotary table by the workpiece fixing means, and the rotary table is driven to rotate by the second driving means while the rotary table is rotated by the rotation driving means. By moving in the direction (axial feed), the cutting tool mounted on the tool post is positioned in the cutting direction to set the cutting amount, and the horizontal moving base is set to the horizontal axis in the machining work area by the first axis feeding means. Cutting feed is performed by moving in the direction (axial feed), and the upper surface of the workpiece fixed on the rotary table by the workpiece fixing means is cut (turned) with a bite tool to flatten the upper surface of the workpiece. Perform chemical processing.

  Then, the measurement of the workpiece fixed on the rotary table by the workpiece fixing means is performed in-process by the measuring means only by moving the horizontal moving table to the measurement work area by the first axis feeding means. Can do. Thereby, the processing accuracy of the processing surface can be measured efficiently and with high accuracy, and various processing can be performed with high throughput and high yield.

In particular, when flattening the upper surface of the work piece with a tool attached to the tool post, a scanning flatness measuring means for scanning the work surface of the work piece and measuring the flatness of the work surface is arranged. simply, the axial feed of the horizontal axis direction of the horizontal moving stage according to the first shaft feed means, by the rotation of the rotary table by the rotation driving means, the flatness measuring means, the scanning for the working surface of the workpiece, This can be done without requiring a special scanning stage. Thereby, in the flattening process of the bump upper surface, the flatness of the processed surface can be efficiently and accurately measured, and the flattening process of the bump upper surface can be performed with high throughput and high yield.

  One embodiment of a processing apparatus according to the present invention will be described with reference to FIGS.

  The processing apparatus by one Embodiment has the base 11 of the 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. Y-axis direction of the shaft feed range of the Y-axis moving table 14, Figure 1, in addition to cutting work area A is divided into the left side in FIG. 2, is the measurement work area B which extends to the left side ing. This means that the Y-axis length of the V-shaped guide rails 12 and 13 on the base 11 is extended in order to secure the measurement work area B.

  The Y-axis moving table 14 is moved in the Y-axis direction by a ball screw 18 that is rotationally driven by a Y-axis servomotor 17. A rotary encoder 19 is attached to the Y-axis servomotor 17 as a Y-axis position detector.

  A rotary table device 20 is mounted on the Y-axis moving table 14. The rotary table device 20 includes a base member 21 fixed to the upper surface of the Y-axis moving table 14 as a fixed side member, a rotary table 27 provided on the base member 21 so as to be rotatable around a vertical axis, and a rotary table 27. And a spindle motor 40 which is a rotation driving means for rotating around a vertical axis.

  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. 4, the silicon wafer W has a plating resist layer Wa and an Au bump Wb formed by plating on the upper surface.

  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. A rotary encoder 76 is attached to the Z-axis servomotor 74 as a Z-axis position detector.

A tool post 77 is attached to the front portion of the Z-axis moving base 73. A tool tool 78 is attached to the tool post 77 downward. Byte tool 78, as shown in FIG. 4, a diamond tool was attach the single crystal or polycrystalline diamond blade portion 80 to the distal end of the shank 79, the cutting work area A, the workpiece The top surface of the silicon wafer W is flattened. In FIG. 2, the tool post 77 is not shown.

  A measuring instrument mounting stand 81 is attached to one side of the base 11. A measuring instrument 85 is attached to the measuring instrument attaching stand 81 by an attaching member 82, an attaching base 83, and a measuring instrument holder 84. The measuring instrument 85 is a displacement measuring instrument, and measures the processing accuracy of the silicon wafer W fixed on the rotary table 27 by the vacuum suction chuck 60 in the measurement work area B. In addition, in FIG. 3, illustration of the measuring instrument 85 and its attaching part is abbreviate | omitted.

  In this embodiment, the measuring instrument 85 is a scanning flatness measuring instrument using a laser and an imaging means, and the axis feed of the Y-axis moving table 14 by the Y-axis servo motor 17 in the measurement work area B and the spindle motor. The processed surface of the silicon wafer W is scanned by rotating the rotary table 27 around the vertical axis by 40, and the flatness (displacement, shape) of the processed surface is measured by an image processing technique.

  As this measuring instrument 85, a surface shape analyzer using a super depth color 3D shape measuring microscope manufactured by Keyence Corporation, a double scan high precision laser measuring instrument, a micron depth manufactured by Nissho Precision Optical Co., Ltd. A height (thickness) measuring machine or the like is applicable.

  Next, the operation of the processing apparatus having the above 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 the silicon wafer W is fixed, the rotary table 27 is rotationally driven around the vertical axis by the spindle motor 40, and in this state, the Z-axis moving table 73 is moved (axially fed) by the Z-axis servo motor 74 in the Z-axis direction. Thus, the cutting tool 78 attached to the tool post 77 is positioned in the cutting direction to set the cutting amount.

  Then, the Y-axis servo motor 17 moves the Y-axis moving table 14 in the Y-axis direction (axis feed) in the cutting work area A to perform cutting feed, and is fixed on the rotary table 27 by the vacuum suction chuck 60. As shown in FIG. 4, the upper surface of the Au bump Wb of the silicon wafer W is turned with a bite tool 78 to perform a flattening process to make the height of the upper surface of the bump uniform.

  In the processing apparatus according to the present invention, the flattening process for aligning the height of the bump upper surface is performed by turning with the cutting tool 78 as described above. Therefore, the throughput is better than the flattening process by polishing such as CMP, and the polishing agent is used. Since the slurry containing it is not used, it is good for the environment, and the problem that the abrasive remains on the silicon wafer W can be solved. In addition, since turning is performed by a tool tool 78 having a single-crystal or polycrystalline diamond blade portion 80, 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 high. Done to precision.

When the first cutting (flattening) by a predetermined number of Y-axis feeds including one in the cutting work area A is completed, the Y-axis servo motor 17 then moves the Y-axis moving table 14 to the measurement work area B. Move to.

In the measurement work area B, the Y-axis servo motor 17 feeds the Y-axis moving table 14 in the Y-axis direction, and the spindle motor 40 rotates the rotary table 27 around the vertical axis so that the flatness measuring means of a measuring instrument 85 performs the scanning with respect to the processing surface of the workpiece (silicon wafer W), it performs the flatness measurement of the processing surface in process.

  As a result, the machining accuracy (flatness) of the machined surface can be scanned and measured efficiently and accurately without requiring a special scanning stage, and if the flatness is not within the required tolerance (allowable value), the Y-axis moving table 14 is returned to the cutting work position A, and cutting is performed again, and it is accurately determined by scanning measurement by the measuring device 85 in the measurement work area B whether the flatness is within the required tolerance, and the work is finished. Thus, it is possible to perform high-precision planarization of the bump upper surface with high throughput and high yield.

  As described above, according to the present invention, it is possible to measure flatness only by using a displacement measuring instrument (measuring instrument 85) by positioning using a feed shaft used for processing, By being able to measure in-process, the flatness measurement can be performed for each wafer, and an excellent effect that stable processing can be performed is obtained.

  When a non-contact measuring instrument such as an optical type is used, the measurement can be performed without stopping the rotation of the main shaft (the rotary table 27), so that the effect of shortening the processing time including the measurement can be obtained. Note that the measuring instrument may be a contact type having a stylus, and in this case, the measurement can be performed regardless of the shape of the bump tip, and the effect that a stable measurement value can be obtained with a simple measuring instrument is obtained. is there.

It is a side view which shows one Embodiment of the processing apparatus by this invention. It is a top view which shows one Embodiment of the processing apparatus by this invention. It is a front view which shows one Embodiment of the processing apparatus by this invention. It is explanatory drawing which shows typically an example of the turning state by the 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 20 Rotary table device 21 Base member 27 Rotary table 40 Spindle motor (rotation drive means)
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 77 Tool post 78 Bite tool 85 Measuring instrument W Silicon wafer Wb Au bump

Claims (1)

The base,
A horizontal moving table provided on the base so as to be movable in the horizontal axis direction and axially fed to a machining work area and a measurement work area different in the horizontal axis direction;
First axis feeding means for driving the horizontal moving table in a horizontal axis direction;
A rotary table provided on the horizontal moving table;
Rotation driving means for rotating the rotation table;
A workpiece fixing means provided on the rotary table and removably fixing the workpiece on the rotary table;
A column fixedly disposed on the base;
A vertical moving table provided in the column so as to be movable in the vertical axis direction;
Second axis feeding means for driving the vertical moving table in the vertical axis direction;
A tool rest that is provided on the vertical movement table and to which a tool for processing the workpiece is attached in the processing work area;
And a measuring means for performing measurements of the workpiece at the location of the measurement work area,
It said measuring means is a flat Mend measuring means you measure the flatness of the processed surface by scanning the machined surface of the workpiece without contact,
After the flattening of the upper surface of the workpiece fixed to the rotary table of the horizontal moving table by the tool attached to the tool rest in the processing work area, the horizontal moving table is moved to the processing work. and sends from the area to the measuring working area, wherein the rotary drive means to continue the rotation of the rotary table of the flatness measuring means, have a row scanning with respect to the processing surface of the workpiece, machining of the workpiece The workpiece is reciprocated between the machining work area and the measurement work area until the flatness of the surface is within the required tolerance, and the flattening process and the flatness measurement are performed. processing equipment that is.