JP2973403B2 - Wafer polishing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a chemical mechanical polishing method (CMP).
The present invention relates to an apparatus for polishing a semiconductor wafer by ical polishing.

[0002]

2. Description of the Related Art As this type of semiconductor wafer polishing apparatus, a polishing apparatus for forming a pressurized air layer between a carrier and a wafer has been proposed. According to this polishing apparatus, a pressing means for pressing a carrier is used. By transmitting the pressing force to the wafer through the pressure air layer, the wafer is pressed against the polishing platen and polished.

Further, the wafer polishing apparatus is provided with a retainer ring surrounding the peripheral edge of the wafer, and the peripheral edge of the wafer is brought into contact with the retainer ring to prevent the wafer from jumping out of the carrier. The retainer ring has high rigidity from the viewpoint of preventing the wafer from jumping out, and is used by being attached to another member having high rigidity.

[0004]

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 is concentrated on the point contact portion of the wafer, there is a defect that a defect such as a crack 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 wafer polishing apparatus provided with a retainer ring that does not cause a defect on a wafer.

[0006]

In order to achieve the above object, the present invention provides a polishing apparatus for polishing a wafer by holding the wafer on a holding head and pressing the wafer against a rotating polishing platen. A head body that rotates and is disposed to face the polishing platen, a carrier that is vertically movably supported by the head body, and that is provided on a lower surface of the carrier and blows air toward a back surface of the wafer. By the air blowing member forming a pressure fluid layer between the carrier and the wafer, by pressing the carrier toward the polishing platen, the wafer to the polishing platen through the pressure fluid layer A pressing means for pressing and a vertically movable part fitted into a lower outer peripheral portion of the carrier to prevent the wafer from jumping out of the carrier, and It is characterized with the ring elastically into a shape along the shape of the peripheral edge of the wafer deformation by the pressing force of the wafer by contact from lateral Doha, in that it consists of.

According to the present invention, when the peripheral edge of the wafer comes into contact with the retainer ring during polishing, the retainer ring follows the shape of the peripheral edge of the wafer by the pressing force from the wafer due to the lateral contact of the wafer. It elastically deforms into a shape.
As a result, the wafer is pressed in a state of being in surface contact with the retainer ring, so that the pressure applied to the wafer from the retainer ring is dispersed, and defects such as cracks and the like do not occur in the wafer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer polishing apparatus according to the present invention will be described below 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. Wafer polishing apparatus 10 shown in FIG.
Is mainly composed of 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 an upper surface thereof. In addition, 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 a motor 20. The polishing platen 12 is rotated in the direction of arrow A by driving a motor 20, and the rotating polishing platen 1 is rotated.
A slurry is supplied from a nozzle (not shown) onto the second polishing pad 16. The holding head 14 is moved up and down by a lifting device (not shown) to hold a wafer to be polished to the holding head 1.
It is raised when setting to 4. The holding head 14 is moved downward when polishing the wafer, and presses the wafer against the polishing pad 16.

FIG. 2 is a plan view of the holding head 14, and FIG. 3 is a longitudinal sectional view taken along line 3-3 in FIG. FIG.
The holding head 14 shown in FIG.
4, guide ring 26, polishing surface adjusting ring 28, retainer ring 30, rubber sheet 32, differential transformer 34,
And a pressing member 36 and the like. The head main body 22 is formed in a disk shape, and a rotating shaft 38 is connected to an upper surface thereof. The head body 22 is rotated in the direction of arrow B by a motor (not shown) connected to the rotating shaft 38. Also,
Air supply paths 40, 42, 44 are formed in the head main body 22. The air supply path 40 extends outside the holding head 14 as shown by a two-dot chain line in FIG. 2, and is provided with an air pump (A) via a regulator (R) 46A.
P: air pump) 48. In addition, the air supply path 4
2 and 44 are also extended outside the holding head 14, and the air supply path 42 is connected to the pump 40 via a regulator 46B.
The air supply path 44 is connected to the pump 40 via a regulator 46C.

The carrier 24 is formed in a substantially cylindrical shape, and is disposed coaxially with the head main body 22 below the head main body 22. Further, a concave portion 25 is provided on the lower surface of the carrier 24.
Is formed, and the porous plate 5 having air permeability is formed in the concave portion 25.
0 is stored. The carrier 24 is provided on the porous plate 50.
Are connected to each other, and these air paths 52, 52 extend outside the holding head 14 as shown by a two-dot chain line in the figure, and are connected to a suction pump (SP: suction). pump) 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 for example, a porous plate made of a sintered body of a ceramic material is used.

The carrier 24 has a large number of air supply passages 78 each having an outlet formed on the outer periphery of the lower surface of the carrier 24.
78 (only two locations are shown in FIG. 2).
The air supply passages 78 are extended outside the holding head 14 as shown by a two-dot chain line in FIG.
It is connected to the air pump 48 via 6D. Therefore, the compressed air from the air pump 48 is supplied to the air supply path 7.
8, 78,... Are blown into the air chamber 56 between the porous plate 50 and the wafer 54. Thereby, the air chamber 56
Is formed, and the pressing force of the carrier 24 is transmitted to the wafer 54 via 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 passages 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 disposed 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 includes two large and small annular stoppers 5.
8, 60 fixed to the lower surface of the head main body 22. As a result, the rubber sheet 32 is divided into a central part 32A and an intermediate part 32B with the stopper 60 as a boundary.
The intermediate part 32B and the outer peripheral part 32C are divided into two parts by the stopper 58 as a boundary. That is, the rubber sheet 32 is
The central portion 32A presses the carrier 24, the intermediate portion 32B presses the pressing member 36, and the outer peripheral portion 32C functions as an air bag for pressing the polishing surface adjusting ring 28.

In the air bag, a rubber sheet 32
The air supply path 40 communicates with an air bag 62 defined by a central portion 32A of the air bag. 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. Further, if the air pressure is adjusted by the regulator 46A, the pressing force (polishing pressure) of the wafer 54 can be controlled.

The guide ring 26 is formed in a cylindrical shape, and is disposed coaxially with the head body 22 below the head body 22. In addition, the guide ring 26 is attached to the rubber sheet 3.
2 and is fixed to the head main body 22. A polishing surface adjusting ring 28 is disposed between the guide ring 26 and the carrier 24. Above the polishing surface adjusting ring 28, an annular air bag 64 defined by the outer peripheral portion 32C of the rubber sheet 32 and the stopper 58 is formed. The air bag 64 communicates with the air supply path 44. Therefore, when compressed air is supplied from the air supply path 44 to the air bag 64, the outer peripheral portion 32 </ b> C of the rubber sheet 32 is elastically deformed by air pressure and presses the annular upper surface 28 </ b> A of the polishing surface adjustment ring 28.
8 is pressed against the polishing pad 16. The pressing force of the polishing surface adjusting ring 28 can be controlled by adjusting the air pressure by the regulator 46C.

The carrier 24 and the polishing surface adjusting ring 28
A pressing member 36 is disposed between the two. The pressing member 36 includes a main body 36A, a head 36B, and a support arm 36.
C, 36C, and legs 36D, 36D. The head 36B of the pressing member 36 and the support arm 3
6C and three leg portions 36D are formed at equal intervals, as shown by dotted lines in FIG.

A main body 36A of the pressing member 36 shown in FIG.
Are arranged in an opening 29 formed in the polishing surface adjusting ring 28. Further, the head 36 of the pressing member 36
B is formed integrally with the main body 36A and is disposed in a gap between the carrier 24 and the polishing surface adjustment ring 28. Above the head 36B, an annular airbag 66 defined by the intermediate portion 32B of the rubber sheet 32 and the stoppers 58, 60 is formed. The air supply path 42 communicates with the air bag 66. Therefore, when compressed air is supplied from the air supply path 42 to the airbag 66, the intermediate portion 32B of the rubber sheet 32 is elastically deformed by air pressure and presses the head 36B of the pressing member 36. Thereby, the lower surface 3 of the leg 36D of the pressing member 36
7 is pressed against the polishing pad 16. The pressing member 36
Can be controlled by adjusting the air pressure with the regulator 46B. In addition, the leg 3
6D is a through hole 28 formed in the polishing surface adjusting ring 28.
C. 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 by the polishing cloth 16 Diamond coated so that it is not polished.

On the other hand, the support arm 36 of the pressing member 36
A differential transformer 34 for detecting the polishing amount of the wafer 54 is provided at the tip of C. This differential transformer 34
Is composed of a core 70, a bobbin 72, and a contact 74. The bobbin 72 is fixed to a distal end portion of a support arm 36C of the pressing member 36, and the core 70 is vertically movable in the bobbin 72. Are located. 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 a polishing amount of the wafer 54 based on a vertical movement amount of the core 70 with respect to the bobbin 72.

A retainer ring 30 is vertically movably fitted to the outer periphery of the lower portion of the carrier 24. The retainer ring 30 contacts the polishing pad 16 during polishing of the wafer 54. The wafer 54 is moved laterally by the rotational force of the polishing pad 16 and is brought into contact with the inner peripheral surface of the retainer ring 30, thereby preventing the wafer 54 from jumping out of the carrier 24 by the retainer ring 30. ing.

Further, since the retainer ring 30 is made of resin, as shown in FIG. 4, the pressing force P from the wafer 54 due to the lateral abutment of the peripheral edge 54A of the wafer 54 as shown in FIG. And elastically deforms into a shape along the shape of the peripheral edge 54A of the wafer 54. Therefore, the wafer 54 is pressed against the retainer ring 30 in a state of being in surface contact with the retainer ring 30 within the range of the angle θ. In addition, as long as it is elastically deformed by the pressing force P, a metal retainer ring is not limited to resin and may be applied.

Next, the operation of the wafer polishing apparatus 10 configured as described above will be described. First, the holding head 1
Then, the suction pump 76 is driven to suck and hold the wafer 54 to be polished on the porous plate 50. Next, the holding head 14 is lowered to hold the holding head 1.
The descending movement is stopped at the position where the contact surface of the polishing surface adjusting ring 28 of No. 4 is in contact with the polishing pad 16. Then, the suction pump 76 is stopped to release the suction of the wafer 54,
The wafer 54 is placed on the polishing pad 16.

Next, the air pump 48 is driven to supply the compressed air to the space 56 through the air passage 78, and the air chamber 56
A pressurized air layer is formed. At this time, the regulator 46D
To control the supply amount of compressed air, and set the pressure of the pressure air layer to a predetermined pressure. Next, pump 4
8 is supplied to the air bag 62 through the air supply path 40, and the center portion 32A of the rubber sheet 32 is elastically deformed by the internal air pressure to press the carrier 24.
The wafer 54 is pressed against the polishing pad 16 via the pressure air layer. Then, the air pressure is adjusted by the regulator 46A to control the internal air pressure to a desired pressure, 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 bag 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 to thereby form the polishing surface adjusting ring. 28, the lower surfaces of the polishing surface adjusting ring 28 and the retainer ring 30 are pressed against the polishing pad 16. Then, the compressed air from the pump 40 is supplied to the airbag 66 via the air supply path 42, and the intermediate portion 32B of the rubber sheet 32 is elastically deformed by the internal air pressure to press the pressing member 36. The lower surface 37 is pressed against the polishing pad 16. Thereafter, the polishing table 12 and the holding head 14 are rotated to start polishing the wafer 54.

During the polishing of the wafer 54, the wafer 54 moves laterally due to the rotation of the polishing pad 16, and is polished in a state where the peripheral edge thereof is pressed against the retainer ring 30. At this time, the retainer ring 30 As shown in FIG. 4, the wafer 54 is elastically deformed by the pressing force P from the wafer 54 into a shape following the shape of the peripheral edge 54A of the wafer 54. As a result, the wafer 54 can be
As a result, the wafer is pressed against the retainer ring 30 in a state of being in surface contact with the wafer, and the pressure applied to the wafer from the retainer ring 30 is dispersed.

On the other hand, the polishing amount of the wafer 54 during the polishing is reduced by the contact 74 of the differential transformer 34 being in contact with the carrier 24.
It is calculated by the arithmetic unit based on the amount of the core 70 descending. When the polishing amount calculated by the arithmetic unit reaches a preset polishing end point, the wafer polishing apparatus 1
0 is stopped, and the polishing of the wafer 54 ends. As a result, when the polishing of one wafer 54 is completed and the second and subsequent wafers 54 are polished, the above-described steps may be repeated.

[0025]

As described above, according to the wafer polishing apparatus according to the present invention, the retainer ring is elastically shaped to follow the shape of the peripheral edge of the wafer by the pressing force of the wafer due to the lateral contact of the wafer. Since the wafer is deformed, the pressure applied to the wafer from the retainer ring is dispersed, and the wafer does not have defects such as cracks.

[Brief description of the drawings]

FIG. 1 is an overall structural diagram 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;

FIG. 3 is a longitudinal sectional view of the holding head taken along line 3-3 in FIG. 2;

FIG. 4 is an explanatory view showing a state in which a retainer ring is elastically deformed by abutting of a wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer polishing apparatus 12 ... Polishing surface plate 14 ... Holding head 16 ... Polishing cloth 24 ... Carrier 30 ... Retainer ring 32 ... Rubber sheet 34 ... Differential transformer 54 ... Wafer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B24B 37/04 H01L 21/304

Claims (1)

(57) [Claims] 1. A polishing apparatus for polishing a wafer by holding a wafer on a holding head and pressing the wafer against a rotating polishing platen, wherein the holding head rotates and is arranged to face the polishing platen; A carrier supported movably in the vertical direction by the head main body; air 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. A blowing member, pressing means for pressing the carrier against the polishing platen, pressing means for pressing the wafer against the polishing platen via the pressure fluid layer, and vertically movable to a lower outer peripheral portion of the carrier. Is inserted ,
Thereby preventing the jumping out of the wafer from the carrier, it elastically deformed into a shape along the shape of the peripheral edge of the wafer with a pressing force of the wafer by contact from lateral wafer
Wafer polishing and wherein the-ring, the this consisting.