JP2012101293A - Machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining method with which all workpieces can be made thin to have a prescribed thickness even when loading a plurality of workpieces via an adhesive sheet inside the opening of one annular frame and grinding and polishing are performed.SOLUTION: A wafer unit 15A in which a first wafer 11 is stuck to the center of an adhesive tape T stuck to the annular frame F, and a plurality of second wafers 13 are stuck to the periphery of the first wafer 11, is formed. Positional relation between a chuck table 36 and a grinding wheel 22 is set so that the outer peripheral edge of a grinding wheel 22 passes through the center of the first wafer 11, the grinding wheel 22 having a radius larger than a length from the rotary axis of the chuck table 36 to the outermost peripheral position of the second wafer 13. While measuring the thickness of the first wafer 11 with a thickness measuring instrument 46, grinding of the first and the second wafers 11, 13, is performed. Grinding feed is stopped when the thickness of the first wafer 11 reaches a prescribed thickness, so that all wafers 11, 13 can be ground to the prescribed thickness.

Description

  The present invention relates to a processing method in which a plurality of workpieces are ground or polished simultaneously to reduce the thickness to a predetermined thickness.

  For example, in the manufacturing process of semiconductor devices and optical devices, a wafer such as silicon, gallium arsenide, or sapphire cut out from an ingot is ground and polished by a grinding device or a polishing device to be reduced to a predetermined thickness and flattened. The

  A plurality of circuit elements are formed on the surface of the thinned and flattened wafer, and the back surface of the wafer is ground and polished to a predetermined thickness, and then the wafer is separated into individual devices by a dicing machine or the like. And various semiconductor devices and optical devices are manufactured.

  During processing by a grinding device or a polishing device, for example, as disclosed in Japanese Patent Application Laid-Open No. 2006-21264, grinding or polishing is performed while measuring the thickness of the workpiece, and the workpiece reaches a predetermined thickness. In such a case, the processing is controlled to end.

  On the other hand, in order to improve the handleability of a workpiece when grinding or polishing a workpiece such as a wafer, and to enable processing of a plurality of workpieces at a time, for example, in an opening of one annular frame There is a method of attaching and processing a plurality of workpieces via an adhesive sheet.

JP 2006-21264 A

  However, when a plurality of workpieces are mounted in the opening of one annular frame via an adhesive sheet to perform grinding or polishing, the thickness of each workpiece cannot be detected during processing. There is a problem that it is difficult to grind or polish the workpiece to a predetermined thickness.

  The present invention has been made in view of these points, and the object of the present invention is to perform grinding and polishing by mounting a plurality of workpieces through an adhesive sheet in the opening of one annular frame. Even in this case, it is to provide a processing method capable of thinning all the workpieces to a predetermined thickness.

  According to the present invention, there is provided a processing method for simultaneously grinding or polishing a plurality of workpieces to reduce the thickness to a predetermined thickness, wherein the opening portion of the annular frame to which the adhesive tape is attached so as to close the opening portion A first workpiece is pasted on the adhesive tape at the center of the first workpiece, and a second workpiece is pasted around the first workpiece on the adhesive tape in the opening. A workpiece unit forming step for forming a workpiece unit; a holding surface for holding the workpiece unit; and a rotating shaft orthogonal to the holding surface. A holding step for holding the workpiece unit by aligning the center of the workpiece, and a grinding wheel or polishing pad having a radius larger than the length from the rotating shaft to the outermost peripheral position of the second workpiece. The outer periphery passes through the center of the first workpiece. The grinding wheel or the polishing pad is rotated while the grinding wheel or the polishing pad is in contact with the workpiece unit held by the chuck table, and the grinding wheel or the polishing pad is held by the chuck table. A processing step for performing grinding or polishing by rotating the workpiece unit and feeding the grinding wheel or the polishing pad in a direction approaching the workpiece unit; and during the processing step, A measuring step of measuring the thickness of one workpiece by a thickness measuring means, and stopping the processing feed when the thickness of the first workpiece reaches a predetermined thickness in the measuring step. There is provided a processing method characterized in that the first workpiece and the second workpiece are thinned to a predetermined thickness.

  According to the present invention, the first workpiece is attached to the center of the opening of the annular frame to which the adhesive tape is attached, and the second workpiece is attached around the first workpiece. The processed workpiece unit is formed.

  The workpiece unit uses a grinding wheel or a polishing pad having a radius longer than the length from the rotation axis of the chuck table holding the workpiece unit to the outermost peripheral position of the second workpiece. Since the processing is performed so that the outer peripheral edge of the pad passes through the center of the first workpiece, a part of the first workpiece is always exposed during the processing.

  Therefore, it becomes possible to measure the thickness of the first workpiece during processing, and when grinding or polishing is performed by mounting a plurality of workpieces through the adhesive sheet in the opening of one annular frame Since the processed workpieces have substantially the same thickness, all the workpieces can be thinned to a predetermined thickness.

It is a schematic perspective view of the grinding device suitable for implementing the processing method of this invention. FIG. 3 is a perspective view of a wafer unit in which a plurality of wafers are supported on an annular frame via an adhesive tape. It is a perspective view which shows the positional relationship of the chuck table and grinding wheel based on the processing method of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external perspective view of a grinding apparatus 2 suitable for carrying out the processing method of the present invention. Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a spindle housing 12 and a support portion 14 that holds the spindle housing 12, and the support portion 14 is attached to a moving base 16 that moves up and down along a pair of guide rails 8. Yes.

  The grinding unit 10 includes a spindle 18 rotatably accommodated in a spindle housing 12, a motor 19 that rotationally drives the spindle 18, a wheel mount 20 that is fixed to the tip of the spindle 18, and a screw fastening to the wheel mount 20. Grinding wheel 22.

  The grinding device 2 includes a grinding unit feed mechanism 32 that includes a ball screw 28 that moves the grinding unit 10 in the vertical direction along a pair of guide rails 8 and a pulse motor 30. When the pulse motor 30 is driven, the ball screw 28 rotates and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the base 4, and a chuck table mechanism 34 is disposed in the recess 4a. The chuck table mechanism 34 includes a chuck table 36 and is moved in the Y-axis direction between a wafer attachment / detachment position A and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown).

  A plurality of clamps 38 are disposed adjacent to the chuck table 36. 40 and 42 are bellows. An operation panel 44 is provided on the front side of the base 4 so that an operator of the grinding apparatus 2 can input grinding conditions and the like.

  FIG. 2 is a perspective view of the wafer unit 15. The wafer unit 15 has a first sapphire wafer (hereinafter abbreviated as a first wafer) 11 attached to an adhesive tape T in the center of the opening of the annular frame F having an adhesive tape T attached to the opening. A plurality of second sapphire wafers (hereinafter abbreviated as second wafers) 13 are stuck on an adhesive tape T around the first wafer 11.

  Therefore, in the wafer unit 15, the first wafer 11 disposed at the center and the plurality of second wafers 13 disposed around the first wafer 11 are supported by the annular frame F via the adhesive tape T. .

  In the processing method of the present invention, first, a wafer unit forming step for forming the wafer unit 15 as shown in FIG. 2 is performed. Next, the center of the first wafer 11 is aligned with the extension line of the rotation axis of the chuck table 36 having a holding surface for holding the wafer unit 15 and a rotation axis orthogonal to the holding surface, and the wafer unit 15 is moved to the chuck table 36. Hold with suction.

  Then, the annular frame F is clamped by the clamp 38 shown in FIG. 1, the annular frame F is pulled down, and the first wafer 11 and the second wafer 13 to be ground protrude above the upper surface of the annular frame F. And The holding step and the pull-down of the annular frame F by the clamp 38 are performed in a state where the chuck table 36 is positioned at the wafer attachment / detachment position A.

  Next, a moving mechanism (not shown) of the chuck table mechanism 34 is driven to move the chuck table 36 in the Y-axis direction, and the wafer unit 15 is positioned at the grinding position B facing the grinding wheel 22. At the grinding position B, the positional relationship between the chuck table 36 and the grinding wheel 22 is as shown in FIG.

  In FIG. 3, the grinding wheel 22 is configured by attaching a plurality of grinding wheels 26 in a ring shape to the lower surface of a wheel base 24. The grinding wheel 22 is detachably attached to the wheel mount 20 with a plurality of screws 23.

  In the processing method of the present invention, the radius of the grinding wheel 22 needs to be larger than the length from the rotation axis of the chuck table 36 to the outermost peripheral position of the second wafer 13. In a state where the grinding wheel 22 is in contact with the workpiece unit 15 held by the chuck table 36 so that the outer peripheral edge of the grinding wheel 22 having such a radius passes through the center of the first wafer 11, the grinding wheel 22 is rotated in the direction of arrow b at 1000 rpm, for example, and the grinding unit 22 is driven by driving the grinding feed mechanism 32 while rotating the workpiece unit 15 held by the chuck table 36 in the direction of arrow a at 300 rpm, for example. The first and second wafers 11 and 13 are ground by feeding in a direction approaching the unit 15.

  During this grinding, the thickness of the first wafer 11 is measured with a contact-type thickness measuring device 46 having a first probe 48a that contacts the surface of the first wafer 11 and a second probe 48b that contacts the adhesive tape T. Perform grinding.

  Since the positional relationship between the wafer unit 15 and the grinding wheel 22 is set so that the outer peripheral edge of the grinding wheel 22 passes through the center of the first wafer 11, a part of the first wafer 11 is always exposed during grinding. Become.

  Accordingly, the thickness of the first wafer 11 can be measured during grinding, and the grinding feed is stopped when the thickness of the first wafer 11 measured by the contact-type thickness measuring device 46 reaches a predetermined thickness. Since the first and second wafers 11 and 13 are sucked and held on the holding surface of the chuck table 36 via the adhesive tape T having a substantially uniform thickness, the first wafer 11 is ground to a predetermined thickness. By detecting this, all the second wafers 13 are also ground to a predetermined thickness.

  The thickness measuring device for measuring the thickness of the first wafer 11 is not limited to the contact-type thickness measuring device 46 having two probes, but a contact thickness measuring device having only one probe, for example, a laser or You may make it use the non-contact-type thickness measuring device using an ultrasonic wave.

  In the embodiment described above, an example in which the present invention is applied to grinding of the first and second wafers 11 and 13 has been described. However, the present invention is not limited to this, and a polishing wheel having a polishing pad is used. The present invention can be similarly applied when polishing the first and second wafers 11 and 13. Further, the workpiece is not limited to a wafer such as a sapphire wafer, and the processing method of the present invention can be applied to any plate-like workpiece.

T adhesive tape F annular frame 2 grinding device 10 grinding unit 11 first wafer 13 second wafer 15 wafer unit 22 grinding wheel 26 grinding wheel 36 chuck table 46 contact-type thickness measuring device

Claims (1)

A processing method in which a plurality of workpieces are ground or polished simultaneously to reduce to a predetermined thickness,
A first work piece is stuck on the pressure-sensitive adhesive tape at the center of the opening of the annular frame on which the pressure-sensitive adhesive tape is stuck so as to close the opening, and around the first work piece, the A workpiece unit forming step of forming a workpiece unit by sticking a second workpiece on the adhesive tape in the opening; and
The workpiece unit is aligned with the center of the first workpiece on an extension line of the rotating shaft of a chuck table having a holding surface for holding the workpiece unit and a rotating shaft orthogonal to the holding surface. Holding step to hold;
The grinding wheel having a radius larger than the length from the rotating shaft to the outermost peripheral position of the second workpiece or the outer peripheral edge of the polishing pad passes through the center of the first workpiece. Alternatively, the grinding wheel or the polishing pad is rotated while the polishing pad is in contact with the workpiece unit held by the chuck table, and the workpiece unit held by the chuck table is rotated. While processing the grinding wheel or the polishing pad in a direction approaching the workpiece unit to perform grinding or polishing,
A measuring step of measuring the thickness of the first workpiece with a thickness measuring means during the processing step,
By stopping the processing feed when the thickness of the first workpiece reaches a predetermined thickness in the measuring step, the first workpiece and the second workpiece are brought to a predetermined thickness. A processing method characterized by thinning.

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