JPH11104957A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suck a wafer to a carrier without sucking a dust to the carrier of the wafer and polish the wafer, while forming the pressurized air layer with a stable pressure between the carrier and wafer. SOLUTION: A porous plate 28 for sucking a wafer 38 is provided on a head main body 24 so as to be projected/sunk freely. The porous plate 28 is energized in a direction projected from the head main body 24 by springs 30 and sucked by driving a suction pump 48 and sunk to the head main body 24. At the sinking time, the wafer 38 sucked by the porous plate 28 is separated from the porous plate 28 and placed on a polish cloth by being contacted to the head main body 24. A pressurized air layer is formed by supplying the air from the blow out port 52 of the head main body 24 and a push-press force is transmitted to the wafer 38 through the pressurized air layer and the wafer 38 is polished.

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).
ical Polishing).

[0002]

2. Description of the Related Art A wafer polishing apparatus disclosed in Japanese Patent Application Laid-Open No. 8-339979 has a wafer holding head and a polishing cloth. An air outlet is formed in the carrier provided in the wafer holding head, and pressurized air is supplied between the carrier and the wafer from the air outlet to form a pressure air layer. The wafer is polished by pressing the wafer against the polishing cloth by pressure.

Recently, there has been proposed a wafer polishing apparatus in which a carrier having the above-mentioned structure is provided with a wafer suction member. According to this wafer polishing apparatus, the wafer can be suctioned by the suction member and carried into the polishing cloth, and the polished wafer can be suctioned again by the suction member and carried out of the polishing cloth. Handling becomes easy.

When a carrier is provided with a suction member, dust such as slurry or polishing debris may be sucked together with the suction member when the wafer is suctioned, and the suction force may be reduced. Is required. Therefore, conventionally, a number of air outlets are formed around the carrier,
Air is blown out from these air outlets with weak pressure,
By forming an air curtain around the adsorption member,
It has been proposed to prevent dust adsorption.

[0005]

However, the above-mentioned wafer polishing apparatus has a drawback that it is difficult to suck a wafer because the suction member and the air outlet are formed on the same plane of the carrier. Such a problem can be solved by providing the suction member at a position protruding from the air outlet and shifting the height position from the air outlet. But,
When the suction member is protruded, a step is generated between the carrier and the wafer, so that it is difficult to form a pressure air layer with a stable pressure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to adsorb a wafer to an adsorption member of a carrier without adsorbing dust, and to provide a stable pressure between the carrier and the wafer. It is an object of the present invention to provide a wafer polishing apparatus capable of forming a pressurized air layer.

[0007]

According to the present invention, in order to achieve the above object, a wafer is pressed against a rotating polishing cloth,
In a wafer polishing apparatus for polishing the surface of a wafer,
A wafer holding head, a suction member that is provided to be able to protrude and retract from the wafer holding head and suctions the back surface of the wafer, an urging member that urges the suction member in a direction to protrude from the wafer holding head, Air suction means for sucking the wafer through the suction member and sucking the wafer to the suction member, and sucking the suction member that sucked the wafer to be immersed in the wafer holding head, thereby detaching the wafer from the suction member; Pressing means for pressing the suction member toward the polishing cloth; and supplying air between the suction member and the wafer from an air outlet formed in the wafer holding head to form a pressure air layer. Air supply means for transmitting the pressing force from the pressing means to the wafer via a pressure air layer. .

According to the present invention, the position of the suction member when suctioning the wafer is at a position protruding from the wafer holding head by the urging force of the urging member, that is, the height position with respect to the air outlet is shifted. The wafer can be easily suctioned by the suction member even while blowing air for preventing dust intrusion from the air blowout port. Therefore, according to the present invention, the wafer can be sucked to the suction member without sucking the dust.

When the wafer is placed on the polishing pad, the carrier is sucked by the air suction means and immersed in the wafer holding head. Thus, the wafer sucked by the suction member comes into contact with the wafer holding head and separates from the suction member, so that the wafer can be placed on the polishing pad. When polishing the wafer, air is supplied between the suction member and the wafer from the air supply means to form a pressure air layer, and the pressing force from the pressing means is transmitted to the wafer via the pressure air layer. Then, the wafer is polished. At this time, the suction member is held at the immersed position by the air pressure of the pressure air layer, so that a pressure air layer having a stable pressure can be formed between the suction member and the wafer.

[0010]

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 an overall configuration 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 table 12 and a wafer 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. Therefore, when the motor 20 is driven, the polishing platen 12 is rotated in the direction of arrow A. Slurry is supplied from a nozzle (not shown) onto the rotating polishing pad 16.

The wafer holding head 14 has a rotating shaft 2
It is provided movably up and down by an elevating and lowering pressing device (pressing means) (not shown) that is connected through the two. The wafer holding head 14 is moved upward by the lifting / lowering device when the wafer to be polished is set on the wafer holding head 14, and is moved downward when polishing the wafer, and is pressed against the polishing pad 16 with a predetermined pressing force. It is pressed and contacted.

FIG. 2 is a longitudinal sectional view of the wafer holding head 14, showing a state before the wafer is held. The wafer holding head 14 shown in FIG. 1 includes a head main body 24, a carrier 26, a porous plate (suction member) 28, a spring 30, and the like. The head main body 24 includes a first head 31, a second head 32 formed in a cup shape, and a cylindrical third head 34 fixed inside the second head 32. The first head 3
The first head 31 and the second head 32 are connected to a rotating shaft 2 connected to the upper surface of the first head 31 via a plurality of springs 33, 33.
2 is rotated in the direction of arrow B in FIG. A polishing surface adjusting ring 36 is formed integrally with the outer peripheral portion of the second head 32. As shown in FIGS. 3 and 4, the polishing surface adjusting ring 36 is pressed against the polishing pad 16 together with the wafer 38 when the wafer 38 is polished.
The stress from the polishing pad 16 is prevented from being concentrated on the edge of the wafer 38. A retainer ring 40 is attached to a lower inner peripheral portion of the polishing surface adjusting ring 36. Since the wafer 38 being polished is surrounded by the retainer ring 40, the wafer 38 is prevented from jumping out of the wafer holding head 14.

The second head 32 has an air suction passage 42
Are formed. Suction port 44 of this air suction path 42
Is formed on the lower surface of the second head 32 and communicates with a space 46 surrounded by the second head 32, the third head 34, and the carrier 26. The air suction passage 42 extends outside the wafer holding head 14 as shown by a two-dot chain line in FIG.
suction pump: air suction means)
Therefore, when the suction pump 48 is driven, the wafer 38 is sucked by the porous plate 28 and held by suction on the lower surface of the porous plate 28. When the suction pump 48 is continuously driven, the carrier 26 is raised with respect to the head main body 24 because the space 46 is sealed by the wafer 38 (see FIGS. 3 and 4). Porous plate 28
Has a number of ventilation paths inside, for example,
What consists of a sintered body of a ceramic material is used.

As shown in FIG. 2, the third head 34 has a plurality of air supply passages 50 (only two are shown in FIG. 2).
Are formed. These air supply paths 50 are formed at predetermined intervals so as to surround the porous plate 28, and the outlets 52 of these air supply paths 50 are formed on the lower surface of the third head 34. The air supply path 50 extends outside the wafer holding head 14 via the second head 32 as shown by a two-dot chain line in FIG.
P: air pump: air supply means). Therefore, when the air pump 54 is driven, pressurized air from the pump 54 is supplied to the space between the porous plate 28, the third head 34 and the wafer 38 through the outlets 52, 52, as shown in FIG. Spouted at 56. Thus, a pressure air layer is formed in the space 56, and the pressing force in the direction indicated by the upper arrow in FIG. 4 is transmitted to the wafer 38 via the pressure air layer. The wafer 38 is pressed against the polishing pad 16 by the pressing force transmitted through the pressure air layer and polished.

As shown in FIG. 2, the carrier 26 is formed in a substantially columnar shape, and is disposed coaxially with the head main body 24 below the head main body 24. A concave portion 27 is formed on the lower surface of the carrier 26, and the porous plate 28 is provided in the concave portion 27. An air passage 58 formed in the carrier 26 communicates with the porous plate 28, and the air passage 58 penetrates the carrier 26 and communicates with the air chamber 46. Thus, when the suction pump 48 is driven, the wafer 38 can be suction-held by the porous plate 28 as shown in FIG.

As shown in FIG. 2, the carrier 26 includes:
A flange 60 is formed on the upper part. The flange 60 is vertically slidably supported on the inner peripheral surface 35 of the third head 34 that defines the air chamber 46. An O-ring 62 is attached to the outer peripheral edge of the flange 60, and the O-ring 62 seals the air chamber 46.
Further, springs 30 are provided between the carrier 26 and the second head 32. This spring 3
The carrier 26 is pressed by the porous plate 2 by the urging force of 0, 30.
8 is urged to protrude from the lower portion of the head main body 24. The springs 30, 30 are provided with recesses 27, 27 formed in the carrier 26 so that their positions do not shift.
Has been inserted. It is sufficient that the spring 30 has enough force to protrude the porous plate 28 from the lower portion of the head main body 24 against the sliding resistance of the O-ring 62. The spring constant which can be moved to the above is applied.

Next, the operation of the wafer polishing apparatus 10 configured as described above will be described. First, after raising the wafer holding head 14, the air pump 54 is driven to blow out weak pressure air from the outlet 52,
An air curtain for preventing dust intrusion is formed around the porous plate 28. Subsequently, the suction pump 48 is driven to suck and hold the wafer 38 to be polished on the porous plate 28.
When the wafer 38 is sucked, the porous plate 28 is at a position protruding from the head main body 24 by the urging force of the springs 30, 30, as shown in FIG. That is, the porous plate 28
The wafer 38 can be easily sucked by the porous plate 28 while blowing air from the outlet 52 because the height of the wafer 38 is shifted downward from the outlet 52. Therefore, in the present embodiment, the wafer 38 can be adsorbed on the porous plate 28 without adsorbing dust.

Next, the wafer holding head 14 is lowered, and the lowering movement is stopped at a position where the polishing surface adjusting ring 36 of the wafer holding head 14 contacts the polishing pad 16. When the suction force of the suction pump 48 is increased, the carrier 26 is sucked and immersed in the head main body 24 because the air chamber 46 is sealed by the wafer 38 as shown in FIG. When the carrier 26 is immersed, the back surface of the wafer 38 adsorbed on the porous plate 28 contacts the lower surface of the third head 34, and the carrier 2
The wafer 38 is pushed by the third head 34 and detached from the porous plate 28 by the continuous immersion operation 6. Thus, the wafer 38 can be placed on the polishing pad 16 as shown in FIG.

When the wafer 38 is placed on the polishing pad 16, the air pump 5 is turned off before the suction pump 48 is stopped.
4 is driven to supply pressurized air from the outlet 52 to the air chamber 56, form a pressurized air layer in the air chamber 56, and transmit the pressing force to the wafer 38 via the pressurized air layer. At this time, since the porous plate 28 is held at the immersed position by the air pressure of the pressure air layer, it is possible to form a stable pressure air layer between the porous plate 28 and the wafer 38. it can. Incidentally, the air pressure for holding the porous plate 28 in the immersed position is controlled by the air pressure directly applied to the porous plate 28 and the air passages 35 formed in the third head 34 and the air chamber 46. There are two pressures, air pressure on the flange 60 of the carrier 26.

Thereafter, the polishing platen 12 and the wafer holding head 14 are rotated to start polishing the wafer 38.
Then, when the polishing amount of the wafer 38 reaches a preset polishing target value, the wafer polishing apparatus 10 is stopped.
Thus, polishing of one wafer 38 is completed. When carrying out the polished wafer 38 from the wafer polishing apparatus 10, first, the pressure of the pressure air layer formed in the air chamber 56 is gradually reduced. As a result, the carrier 26 starts to descend by the urging force of the spring 30, and the porous plate 28 comes into close contact with the back surface of the wafer 38. Next, after the suction pump 48 is driven to suction-hold the wafer 38 with the porous plate 28, the wafer holding head 14
And move it toward the unloading section. Thus, the unloading of the polished wafer 38 ends. When polishing the second and subsequent wafers 38 continuously, the above-described steps are repeated.

[0021]

As described above, according to the wafer polishing apparatus of the present invention, when the wafer is suctioned, the suction member is
Since the wafer is held at a position protruding from the wafer holding head, the wafer can be sucked to the suction member without sucking dust. In addition, since the suction member is held at a position immersed in the wafer holding head when polishing the wafer, a pressure air layer having a stable pressure can be formed between the suction member and the wafer.

[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 longitudinal sectional view of a wafer holding head applied to the wafer polishing apparatus of FIG. 1, showing a state before holding a wafer;

FIG. 3 is a view showing a state in which a wafer is held in a vertical sectional view of the wafer holding head.

FIG. 4 is a longitudinal sectional view of the wafer holding head showing a state during wafer polishing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer polishing apparatus 12 ... Polishing plate 14 ... Wafer holding head 16 ... Polishing cloth 24 ... Head main body 26 ... Carrier 28 ... Porous plate 30 ... Spring 48 ... Suction pump 54 ... Air pump

Claims (1)

[Claims] 1. A wafer is pressed against a rotating polishing cloth,
In a wafer polishing apparatus for polishing a front surface of a wafer, a wafer holding head, a suction member provided to be capable of protruding and retracting on the wafer holding head and suctioning a back surface of the wafer, and projecting the suction member from the wafer holding head An urging member for urging in the direction, by suctioning the wafer via the suction member and adsorbing the wafer to the suction member, and by suctioning the suction member that sucked the wafer and immersing it in the wafer holding head, Air suction means for detaching the wafer from the suction member, pressing means for pressing the suction member toward the polishing cloth, and between the suction member and the wafer from an air outlet formed in the wafer holding head. A pressure air layer is formed by supplying air, and the pressing force from the pressing means is applied to the wafer via the pressure air layer. Wafer polishing apparatus characterized by comprising a an air supply means for transmission.