WO2001023138A1

WO2001023138A1 - Wafer grinder

Info

Publication number: WO2001023138A1
Application number: PCT/JP1999/005291
Authority: WO
Inventors: Takao Inaba; Minoru Numoto
Original assignee: Tokyo Seimitsu Co., Ltd.
Priority date: 1998-03-30
Filing date: 1999-09-28
Publication date: 2001-04-05
Also published as: JPH11277417A; JP2973403B2

Abstract

A wafer grinder is provided with a retainer ring unlikely to damage a wafer. In the wafer grinder, a wafer (54) is ground with a layer of compressed air formed between a career (24) and the wafer (54), and a retainer ring (30) for preventing the wafer (54) from leaving the career (24) is formed such that it elastically deforms to meet the border of the wafer (54) when pressed by the wafer (54). Since the wafer (54) is urged in contact with the retainer ring (30) during grinding, the pressure acting on the wafer (54) from the retainer ring (30) is distributed so that the wafer (54) may not suffer damage.

Description

ゥ Niha polishing machine

Technical field

The present invention relates to a wafer polishing apparatus, and more particularly, to a polishing apparatus for semiconductors by chemical mechanical polishing (CMP). Light

Background technology

As this type of semiconductor wafer polishing apparatus, a polishing apparatus that forms a pressurized air layer between a carrier and a wafer has been proposed. According to this polishing apparatus, a pressing force from pressing means for pressing the carrier is provided. Is transmitted through the pressure air layer to ゥヱ, so that the ハ is pressed against the polishing platen and polished.

Further, the wafer polishing apparatus is provided with a retainer ring surrounding the periphery of the wafer. By bringing the periphery of the wafer into contact with the retainer ring, the wafer is removed from the carrier. Prevents jumping out. The retainer ring has high rigidity from the viewpoint of preventing the protrusion from popping out, and is used by being attached to another member having a high level of Oka I.

However, since the wafer polishing apparatus has high rigidity on the retainer ring side, the wafer is pressed against the retainer ring in a point contact state. As a result, since the pressure concentrates on the point contact portion, defects such as cracks may occur in the contact portion.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a polishing machine having a retainer ring that does not cause a defect in the device.

Disclosure of the invention

In order to achieve the above object, the present invention provides a rotating head that holds a wafer on a holding head. In a polishing apparatus for polishing a wafer by pressing the polishing head against a polishing platen, the holding head is rotated, and the head body is disposed opposite to the polishing platen; A carrier supported movably upward and downward, and a pressure fluid layer formed between the carrier and the wafer by blowing air toward the back surface of the carrier provided on the lower surface of the carrier. An air blowing member to be pressed, a pressing means for pressing the carrier toward the polishing platen by pressing the carrier toward the polishing platen, and a pressing means for pressing the pennies against the polishing platen via the pressure fluid layer. It is fitted so that it can move up and down, prevents the wafer from jumping out of the carrier, and follows the shape of the periphery of the wafer with the pressing force of 18 by the abutting from the 18 side. Elastic to shape It is characterized by comprising a deformable ring and

According to the present invention, when the peripheral edge of the roller contacts the retainer ring during polishing, the retainer ring is pressed by the pressure from the roller due to the lateral contact of the roller. It elastically deforms into a shape that follows the shape of the periphery. As a result, since the sheet is pressed in a state of being in surface contact with the retainer ring, the pressure applied to the sheet A from the retainer ring is dispersed, and defects such as cracks and the like do not occur in the sheet A. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an overall structural view of a wafer polishing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of a holding head applied to the wafer polishing apparatus of FIG. 1, and FIG. FIG. 3 is a longitudinal sectional view of the holding head taken along line 3-3 in FIG. 2, and FIG. 4 is an explanatory view showing a state in which the retainer ring is elastically deformed by the contact of the wafer. BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a penniha polishing apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a structural diagram of a wafer polishing apparatus according to an embodiment of the present invention. The polishing apparatus 10 shown in FIG. 1 mainly includes a polishing platen 12 and a holding head 14. The polishing platen 12 is formed in a disk shape, and a polishing cloth 16 is provided on the upper surface thereof. 0

Is provided. Further, a spindle 18 is connected to a lower portion of the polishing table 12, and the spindle 18 is connected to an output shaft (not shown) of the motor 20. The polishing platen 12 rotates in the direction of arrow A by driving the motor 20, and slurry is supplied from a nozzle (not shown) onto the polishing cloth 16 of the rotating polishing platen 12. The holding head 14 is moved up and down by an elevating device (not shown), and is moved up when the polishing object is set on the holding head 14. In addition, the holding head 14 is moved downward when polishing the wafer, and presses the wafer against the polishing cloth 16.

FIG. 1 is a plan view of the holding head 14, and FIG. 3 is a longitudinal sectional view taken along line 3-3 in FIG. The holding head 14 shown in Fig. 3 is composed of the head body 22, carrier 24, guide ring 26, polished surface adjustment ring 28, retainer ring 30 and rubber sheet 3 2 , A differential transformer 34, and a pressing member 36.

The head body 22 is formed in a disk shape, and has a rotating shaft 38 connected to the upper surface thereof, and is rotated in the direction of arrow B by a motor (not shown) connected to the rotating shaft 38. . Further, air supply paths 40, 42, and 44 are formed in the head body 22. The air supply passage 40 extends outside the holding head 14 as shown by a two-dot chain line in FIG. 3, and is supplied through an air pump (AP: air) through a regulator (R) 46 A. pump) 4 8 Similarly, the air supply path 42.44 extends outside the holding head 14, and the air supply path 42 is connected to the pump 48 via the regulator 46B and to the air supply path 4 Numerals 4 are respectively connected to pumps 48 through regulators 46C.

The carrier 24 is formed in a substantially cylindrical shape, and is arranged below the head body 22 coaxially with the head body 12. In addition, a concave portion 25 is formed on the lower surface of the carrier 24, and a porous plate 50 having air permeability is accommodated in the concave portion 25. Air passages 52.5.2 formed in the carrier 24 are communicated with the porous plate 50, and these air passages 5 and 52 are held as shown by a two-dot chain line in the figure. It extends outside of the port 14 and is connected to a suction pump (SP) 76. Therefore, when the suction pump 76 is driven, the wafer 54 is sucked by the porous plate 50 and held by the porous plate 50. The porous plate 50 has a large number of air passages inside, and the corrected paper (Rule 91) For example, a material made of a sintered body of a ceramic material is used.

The carrier 24 is provided with a number of air supply paths 78, 78, each having an ejection port formed on the outer peripheral portion of the lower surface of the carrier 24 (only two force points are shown in FIG. 3). . The air supply passages 78, 78 ... extend outside the holding head 14 as shown by a two-dot chain line in the figure, and are connected to the air pump 48 via a regulator 46D. ing. Therefore, the compressed air from the air pump 48 is blown out to the air chamber 56 between the porous plate 50 and the porcelain plate 54 through the air supply paths 78, 78. As a result, a pressure air layer is formed in the air chamber 56, and the pressing force of the carrier 24 is transmitted to the carrier 54 through the pressure air layer. The wafer 54 is pressed against the polishing pad 16 by the pressing force transmitted through the pressure air layer. The air blown out from the air supply paths 78, 78,... Is exhausted to the outside through an exhaust hole (not shown) formed in the polishing surface adjustment ring 28.

On the other hand, one rubber sheet 32 is arranged between the head body 22 and the carrier 24. This rubber sheet 32 is formed in a disk shape with a uniform thickness. The rubber sheet 32 is fixed to the lower surface of the head body 2 by two large and small annular stoppers 58, 60. As a result, the rubber sheet 32 is divided into a center part 32 A and a middle part 32 B with the clasp 60 as a boundary, and the middle part 32 B and a peripheral part with the clasp 58 as a boundary. There are 2 divided into 3 2 C. That is, the rubber sheet 32 is divided into three parts by the stoppers 58, 60, and the central part 32A presses the carrier 24, the intermediate part 32B presses the pressing member 36, and the outer periphery. The part 32C functions as an air bag for pressing the polishing surface adjustment ring 28.

The air supply path 40 communicates with an air bag 62 defined by a central portion 32 A of the rubber sheet 32 among the air bags. Therefore, when compressed air is supplied from the air supply path 40 to the airbag 62, the central portion 32A of the rubber sheet 32 is elastically deformed by air pressure and presses the upper surface of the carrier 24. Thereby, a pressing force of the wafer 54 against the polishing pad 16 can be obtained. Also, by adjusting the air pressure with the regulator 46 A, the pressing force (polishing pressure) of the wafer 54 can be controlled. The guide ring 26 is formed in a cylindrical shape and is provided at the lower part of the head body 22 in a corrected form (Rule 91). 22 Coaxially arranged with 2. The guide ring 26 is fixed to the head body 22 via a rubber sheet 32. A polished surface adjustment ring 28 is arranged between the guide ring 26 and the carrier 24.

Above the polishing surface adjusting ring 28, an annular air bag 64 defined by an outer peripheral portion 32C of the rubber sheet 32 and a stopper 58 is formed. The air supply path 44 is communicated with the air bag 64. Therefore, when compressed air is supplied from the air supply path 44 to the airbag 64, the outer peripheral portion 32C of the rubber sheet 32 is elastically deformed by air pressure, and the annular upper surface 28 of the polishing surface adjusting ring 28 is formed. A is pressed, and the annular lower surface 28 B of the polishing surface adjusting ring 8 is pressed against the polishing cloth 16. The pressing force of the polished surface adjustment ring 28 can be controlled by adjusting the air pressure with a regulator at 46 C overnight.

A pressing member 36 is disposed between the carrier 2 and the polishing surface adjusting ring 28. The pressing member 36 is composed of a main body 36A, a head 36B, support arms 36C and 36C, and legs 36D and 36D. The head 36B, the supporting arm 36C, and the leg 36D of the pressing member 36 are formed at regular intervals of three as shown by dotted lines in FIG.

The main body 36 A of the pressing member 36 shown in FIG. 3 is disposed in an opening 29 formed in the polishing surface adjusting ring 18. The head 36 B of the pressing member 36 is formed integrally with the main body 36 A, and is arranged in a gap between the carrier 24 and the polishing surface adjusting ring 28.

Above the head 36B, an annular airbag 66 defined by an intermediate portion 32B of the rubber sheet 32 and stoppers 58, 60 is formed. The air supply path 42 is connected to the air bag 66. Therefore, when compressed air is supplied from the air supply passage 42 to the air bag 66, the intermediate portion 32B of the rubber sheet 32 is elastically deformed by air pressure, and the head 36B of the pressing member 36 is compressed. Press. As a result, the lower surface 37 of the leg 36D of the pressing member 36 is pressed against the polishing pad 16. In addition, the pressing force of the pressing member 36 can be controlled by adjusting the air pressure with a regulator 46B. Ma The leg 36D is disposed in a through hole 28C formed in the polished surface adjustment ring 28. Further, the pressing member 38 is formed using an amber having a very small coefficient of thermal expansion as a base material in order to prevent thermal expansion due to polishing processing heat, and the lower surface 37 pressed against the polishing cloth 16 is Abrasive cloth 16 is coated with diamond so as not to be polished. On the other hand, a differential transformer 34 for detecting the amount of polishing of the wafer 54 is provided at the tip of the support arm 36 C of the pressing member 36. The differential transformer 34 includes a core 70, a bobbin 72, and a contact 74, and the bobbin 72 is fixed to a distal end portion of a support arm 36 C of a pressing member 36, The core 70 is vertically movably arranged in the bobbin 72. The contact 74 is provided below the core 70, and the contact 74 is in contact with the carrier 24. An arithmetic unit (not shown) is connected to the bobbin 72, and the arithmetic unit calculates the amount of polishing of the penny 54 based on the amount of vertical movement of the core 70 with respect to the bobbin 72.

By the way, a retainer ring 30 is vertically movably fitted into the outer periphery of the lower part of the carrier 24. The retainer ring 30 is brought into contact with the polishing pad 16 during polishing of the wafer 54. Then, the wafer 54 is moved laterally by the rotational force of the polishing pad 16 and abuts on the inner peripheral surface of the retainer ring 30, whereby the wafer from the carrier 24 is moved. The jumping out of 5 4 is blocked by the retaining ring 30.

In addition, since the retainer ring 30 is made of resin, as shown in FIG. 4, a pressing force P from the wafer 54 due to the lateral contact of the peripheral edge 54 A of the wafer 54 as shown in FIG. Deforms from the original shape indicated by the two-dot chain line, and elastically deforms into a shape along the shape of the periphery 54 A of the wafer 54. Therefore, the wafer 54 is pressed against the retainer ring 30 in a state of surface contact with the retainer ring 30 within a range of the angle Θ. In addition, as long as it is elastically deformed by the pressing force P, not only resin but also metal retainer rings may be applied.

Next, the operation of the wafer polishing apparatus 10 configured as described above will be described. First, after raising the holding head 14, the suction pump 76 is driven to adsorb and hold the wafer 54 to be polished on the porous plate 50. Next, the holding head 14 is lowered, and the lowering movement is stopped at a position where the contact surface of the polishing surface adjusting ring 28 of the holding head 14 comes into contact with the polishing pad 16. Then, the suction pump 76 is stopped to release the suction of the above-mentioned No. 184, and the No. 154 is placed on the polishing pad 16.

Next, the air pump 48 is driven to supply the compressed air to the space 56 via the air path 78, and a pressure air layer is formed in the air chamber 56. At this time, by controlling the regulator 46 D, the supply amount of compressed air is adjusted, and the pressure of the pressure air layer is set to a predetermined pressure. Next, the compressed air from the pump 48 is supplied to the air bag 62 through the air supply passage 40, and the center portion 32A of the rubber sheet 32 is elastically deformed by the internal air pressure to make the carrier 2 elastic. 4 is pressed, and 18 5 is pressed against the polishing pad 16 through the pressure air layer. Then, the internal air pressure is adjusted to a desired pressure by adjusting the air pressure with a regulator at 46 A, and the pressing force of the wafer 54 against the polishing pad 16 is kept constant.

At the same time, the compressed air from the pump 40 is supplied to the air-back 64 through the air supply path 44, and the outer peripheral portion 32C of the rubber sheet 32 is elastically deformed by the internal air pressure. The polishing surface adjustment ring 28 is pressed, and the lower surfaces of the polishing surface adjustment ring 28 and the retainer ring 30 are pressed against the polishing cloth 16. Then, the compressed air from the pump 40 is supplied to the airbag 66 through the air supply path 42, and the intermediate portion 32B of the rubber sheet 32 is elastically deformed by the internal air pressure to cause the pressing member 36 to deform. Then, the lower surface 37 of the pressing member 36 is pressed against the polishing pad 16. Thereafter, the polishing plate 12 and the holding head 14 are rotated to start polishing the wafer 54.

During polishing of the wafer 54, the wafer 54 is moved in the lateral direction by the rotation of the polishing cloth 16 and is polished in a state where its periphery is pressed against the retaining ring 30. However, as shown in FIG. 4, the retainer ring 30 is elastically deformed by the pressing force P from the wafer 54 to a shape following the shape of the peripheral edge 54 A of the wafer 54. As a result, the carrier 184 is pressed against the retainer ring 30 in surface contact with the retainer ring 30, and the pressure applied to the retainer ring 30 from the retainer ring 30 is dispersed. Therefore, there are no defects such as cracks and cracks. On the other hand, the polishing amount during polishing is as follows.The contact amount of the contact 74 of the differential transformer 34 is in contact with the carrier 24. It is calculated by the arithmetic unit based on the amount of fall and fall of 70.

Then, when the polishing amount calculated by the arithmetic unit reaches a preset polishing end point, the polishing apparatus 10 is stopped, and the polishing of FIG. 54 ends. Thus, the polishing of one wafer 54 is completed, and the polishing of the second wafer and subsequent wafers 54 may be repeated by repeating the above-described steps.

Industrial applicability

As described above, according to the polishing machine according to the present invention, the retainer ring is shaped into the shape of the peripheral edge of 18 by the pressing force of 18 due to the lateral contact of the A8. Since it is elastically deformed into a shape along the shape, the pressure applied to the surface from the retainer is dispersed, and defects such as cracks and chips do not occur in the structure.

Claims

The scope of the claims

1. In a polishing machine that polishes the wafer by holding the wafer on the holding head and pressing it against the rotating polishing platen,

The holding head is

A head body that rotates and is arranged to face the polishing platen;

A carrier supported movably in the vertical direction by the head body;

An air blowing member provided on the lower surface of the carrier and blowing air toward the back surface of the wafer to form a pressure fluid layer between the carrier and the wafer; Pressing means for pressing the wafer to the polishing platen via the pressure fluid layer by pressing the platen against the platen;

The carrier is vertically movably fitted to the outer periphery of the lower portion of the carrier to prevent the eaves from jumping out of the carrier. A ring that elastically deforms into a shape along the shape of the periphery of

Pano, a polishing apparatus, comprising: