JP2014075408A - Holding table and holding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding table suitable for holding a workpiece having a thickness variation, and to provide a holding method for holding a workpiece by using the holding table.SOLUTION: In a holding table having a suction holding part for holding a workpiece, the suction holding part is divided into a plurality of small region holding parts for locally holding a workpiece. The holding table includes a plurality of height position changing means for changing the height position of the plurality of small region holding parts, respectively, and a suction path having one end opening to the plurality of small region holding parts, respectively, and the other end connected with a suction source.

Description

  The present invention relates to a holding table and a holding method for holding a workpiece by the holding table.

  In the manufacturing process of a semiconductor device, a grid-like division planned line called street is formed on the surface of a wafer made of silicon or a compound semiconductor. Then, devices such as ICs and LSIs are formed in the respective areas partitioned by the division lines.

  These wafers are ground on the back by a grinding machine and thinned to a predetermined thickness, then cut along the streets by a cutting machine or laser processing machine, and divided into individual chips. Manufactured. The semiconductor device manufactured in this way is widely used in various electric devices such as mobile phones and personal computers.

  A processing apparatus such as a cutting apparatus, a grinding apparatus, or a laser processing apparatus performs a process such as a cutting process, a grinding process, or a laser process on a workpiece while holding the workpiece such as a wafer on a holding table (chuck table). .

JP 11-254259 A JP 2001-287141 A

  However, if the workpiece itself or a protective member attached to the workpiece and supporting the workpiece has a thickness variation, the upper surface of the workpiece held by the holding table is not flat (level). For example, the following problems occur.

  In a cutting machine, for example, when the cutting groove is formed by a dicing before grinding method, the cutting depth varies, the division timing shifts during chip division by grinding, and chipping occurs in some chips. . In a grinding device, a polishing device, or a cutting tool, the flatness accuracy of the workpiece after grinding, polishing, and cutting is deteriorated.

  When forming a laser processing groove or modified layer using a laser processing device, a laser processing groove with a certain depth or a modified layer cannot be formed at a certain height inside the work piece, and it is divided when dividing. Defects may occur.

  The present invention has been made in view of these points, and an object of the present invention is to provide a holding table suitable for holding a workpiece having a thickness variation and a workpiece using the holding table. It is providing the holding method which hold | maintains.

  According to the first aspect of the present invention, there is provided a holding table having a suction holding portion for holding a workpiece, wherein the suction holding portion is divided into a plurality of small area holding portions for locally holding the workpiece. A plurality of height position changing means for respectively changing the height positions of the plurality of small area holding portions, and suction with one end opening to each of the plurality of small area holding portions and the other end connected to a suction source And a holding table characterized by comprising a path.

  According to a third aspect of the present invention, there is provided a holding method for holding a workpiece by the holding table according to the first or second aspect, wherein the workpiece is placed on the holding table and sucked and held. A height position detecting step for detecting the upper surface height position of the workpiece held on the holding table at a plurality of points; and after the height position detecting step is carried out, And a height position changing step of changing the height position of the holding portion to make the upper surface height of the workpiece flush with each other.

  In the holding table of the present invention, the suction holding unit is divided into a plurality of small region holding units, and the workpiece is locally held by each small region holding unit. Since it has a height position changing means to change the height position of the small area holding part, even if there is a thickness variation in the workpiece itself or the protective member attached to the workpiece, the upper surface of the workpiece is It can be kept flat (flat) and the above-mentioned problems can be solved.

It is a top view of the holding table concerning an embodiment. It is a longitudinal cross-sectional view of the holding table which concerns on embodiment. It is a longitudinal cross-sectional view of the holding table which shows a mounting step. It is a longitudinal cross-sectional view of the holding table which shows a suction holding step. It is an expanded sectional view which shows a height position detection step. It is an expanded sectional view which shows a height position change step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a plan view of a holding table (chuck table) 2 according to an embodiment of the present invention is shown. The holding table 2 includes a frame body 4 made of SUS or the like and a suction holding section 6 surrounded by the frame body 4.

  The suction holding unit 6 is made of, for example, porous ceramics and is divided into a plurality of small region holding units 8 that locally hold the workpiece. As shown in the sectional view of FIG. 2, each small area holding portion 8 is supported by a piezo actuator 10. The workpiece is locally held by the holding surface 8a of each small area holding unit 8.

  Each small area holding unit 8 is selectively connected to a suction source 18 via a suction path 12, a common suction path 14 and an electromagnetic switching valve 16 formed in the piezoelectric actuator 10. Each piezo actuator 10 has a pair of electrodes 20, 22 that are connected to the positive side of the power source 24, and the electrode 22 is connected to the negative side of the power source 24 via an applied voltage changing means 26 such as a variable resistor. It is connected.

  Hereinafter, the operation of the holding table 2 of the present embodiment will be described. As shown in FIG. 3, a workpiece 11 such as a wafer is placed on the suction holding unit 6 of the holding table 2. At this time, the electromagnetic switching valve 16 is positioned at the cutoff position, and no negative pressure is applied to the suction holding unit 6.

  As shown in FIG. 4, when the electromagnetic switching valve 16 is switched to the connection position, negative pressure acts on each small area holding portion 8 of the suction holding portion 6 via the electromagnetic switching valve 16, the common suction path 14, and the suction path 12. The workpiece 11 is sucked and held by the holding table 2.

  Next, as shown in FIG. 5, the upper surface 11 a of the workpiece 11 is scanned by the non-contact type height position detector 28, and the height position of the upper surface 11 a of the workpiece 11 held by the holding table 2. Are detected at a plurality of points (height position detection step).

  The detected height positions of the plurality of points are stored in the memory of the processing apparatus provided with the holding table 2. As the non-contact type height position detector, a known laser height position detector or ultrasonic height position detector can be used.

  After performing the height position detection step, the piezoelectric actuator 10 at a position necessary for flattening the upper surface 11a of the workpiece 11 is driven with a drive voltage controlled by controlling the applied voltage changing means 26. Then, as shown in FIG. 6, the height position of the upper surface 11a of the workpiece 11 is made flush as indicated by reference numeral 11a '(height position changing step).

  In this height position changing step, it is not necessary to drive all of the piezo actuators 10 disposed under the respective small area holding sections 8, and the height of the upper surface 11a of the workpiece 11 detected in the height position detecting step. In accordance with the position, the piezo actuator 10 necessary to make the height position flush with each other is driven with the applied voltage controlled by the applied voltage changing means 26.

  Therefore, even when the workpiece 11 itself or a protective member that is attached to the workpiece 11 and supports the workpiece has a thickness variation, the upper surface 11a of the workpiece 11 is held flat (equal). be able to.

2 Holding table (chuck table)
4 Frame body 6 Suction holding section 8 Small area holding section 10 Piezo actuator 12 Suction path 14 Common suction path 16 Electromagnetic switching valve 18 Suction source 20, 22 Electrode 24 Power supply 26 Applied voltage changing means 28 Height position detector

Claims (3)

A holding table having a suction holding unit for holding a workpiece,
The suction holding unit is divided into a plurality of small region holding units that locally hold the workpiece,
A plurality of height position changing means for respectively changing the height positions of the plurality of small area holding units;
A suction path having one end opened to each of the plurality of small area holding portions and the other end connected to a suction source;
A holding table characterized by comprising:   The holding table according to claim 1, wherein the height position detecting means is constituted by a piezo actuator. A holding method for holding a workpiece with the holding table according to claim 1 or 2,
A holding step of placing the workpiece on the holding table and holding the workpiece by suction;
A height position detecting step for detecting the upper surface height position of the workpiece held by the holding table at a plurality of points;
After performing the height position detecting step, the height position changing step of changing the height position of the small area holding portion by the height position changing means to make the upper surface height of the workpiece flush with each other,
The holding method characterized by including.

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