JP2000042900A - Cmp polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve in-plane uniformity of the machining quantity in a CMP polishing device for polishing machined material of plate shape using a polishing tool of small area compared to a polished surface. SOLUTION: A polishing head 5 is composed of a pressing mechanism part 17, a spindle 9, a driving motor 10 and a ball screw 29 and fitted to the lower side of a turning arm 12 through the ball screw 29. The pressing mechanism part 17 is provided opposedly to a turntable 2, and polishing cloth 20 is mounted on the lower face of the pressing mechanism part 17. The diameter of the effective polishing surface of the polishing cloth 20 is smaller than the diameter of a silicon wafer 1. The polishing head 5 is vertically moved along guide mechanism 8 by driving the ball screw 29 using a servo motor 27. The pressure of an operating fluid supplied to the pressing mechanism part 17 is controlled through a pressure control valve 31 or the like to maintain the pressing force of the polishing cloth 20 to the silicon wafer 1 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP apparatus used for flatly polishing the surface of a flat workpiece such as a silicon wafer, and more particularly, to a CMP apparatus which has an area smaller than the area of the polished surface of the workpiece. The present invention relates to a type of CMP apparatus using a polishing tool having a small area.

[0002]

2. Description of the Related Art Among CMP apparatuses (chemical mechanical polishing apparatuses),
In an apparatus used for polishing a relatively large-sized workpiece, a polishing tool having a small area compared to the area of the polished surface of the workpiece is used, and the turning tool or the linear moving mechanism is used. Thus, the entire surface to be polished is polished while moving in a plane parallel to the surface to be polished.

FIG. 5 shows a conventional CM based on such a system.
1 shows an example of a P device. The silicon wafer 1 as the workpiece is held by being attracted to the upper surface of the turntable 2. The turntable 2 is fixed to an upper end of the drive shaft 3. A polishing head 5 is disposed above the turntable 2, and an abrasive supply nozzle 4 is disposed adjacent to the polishing head 5.

The polishing head 5 includes a top ring 7, a main shaft 9, a drive motor 10, an air cylinder 11, and the like. The polishing head 5 is mounted below the turning arm 12 via the air cylinder 11. Further, the polishing head 5 is supported from the side by the guide mechanism 8 and can move up and down along the guide mechanism 8. This guide mechanism 8 is also attached below the turning arm 12. Polishing head 5
Is disposed at a position facing the turntable 2, and a polishing cloth 6 is attached to the lower surface of the top ring 7. Here, the diameter of the polishing pad 6 is smaller than the diameter of the silicon wafer 1. By the drive motor 10,
Rotation is applied to the top ring 7 via the main shaft 9. Further, a downward pressing force is applied to the top ring 7 via the main shaft 9 by the air cylinder 11.

A polishing agent is supplied from a polishing agent supply nozzle 4 to a surface (a surface to be polished) of the silicon wafer 1, and the turntable 2 and the top ring 7 are driven to rotate. By pressing the polishing cloth 6 against the surface (polished surface) of the silicon wafer 1 using the air cylinder 11 while rotating the polishing pad in a plane parallel to the polished surface, the entire polished surface is polished. Will be

In a CMP apparatus of the type described above, the polishing head 5 is liable to change its position in the vertical direction during the turning movement of the turning arm 12. Along with this, the contact state between the polishing pad 6 and the silicon wafer 1, that is, the contact area and the contact pressure change, and as a result, the uniformity of the processing amount in the polished surface is impaired.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the conventional CMP polishing apparatus as described above.
SUMMARY OF THE INVENTION An object of the present invention is to provide a type of CM in which a flat plate-shaped workpiece is polished using a polishing tool having a smaller area than a surface to be polished.
CM with excellent in-plane uniformity of processing amount in P polishing machine
P polishing apparatus is provided.

[0008]

SUMMARY OF THE INVENTION A CMP polishing apparatus according to the present invention comprises a turntable on which a flat workpiece is held on the surface and a polishing tool having a smaller area than the surface to be polished of the workpiece. And, while rotating this polishing tool,
A polishing head for pressing the polishing tool against the surface to be polished by the pressure of the working fluid, and a moving means for moving the polishing head in a plane parallel to the surface to be polished
In the polishing apparatus, a detector that detects the pressure of the working fluid, and a pressure controller that feedback-controls the pressure of the working fluid so that the pressure detected by the detector matches a preset value. A CMP polishing apparatus comprising:

When the polishing tool is a polishing cloth made of an elastic material, preferably, the CMP apparatus is configured such that the pressure of the working fluid directly acts on the back surface of the polishing cloth. Further, when the polishing tool is a polishing cloth made of an elastic body, preferably, a depression having a cylindrical side wall and a flat bottom is formed at the center thereof, and the pressure of the working fluid is formed inside the depression. It is configured to work directly.

According to the CMP apparatus of the present invention, when the polishing head is moved in a plane parallel to the surface to be polished, a fine vertical direction is applied to a turning mechanism or a linear moving mechanism on which the polishing head is mounted. Even if the position fluctuation occurs, the force for pressing the polishing tool against the surface to be polished can be maintained at a constant value by performing feedback control of the pressure of the working fluid acting on the polishing tool. As a result, it is possible to realize high accuracy in the in-plane uniformity of the processing amount.

[0011]

FIG. 1 shows an example of a CMP polishing apparatus according to the present invention. In the figure, 1 is a silicon wafer (workpiece), 2 is a turntable, 5 is a polishing head, 17
Is a pressure mechanism, 20 is a polishing cloth (polishing tool), 12 is a revolving arm (moving means), 29 is a ball screw, 30 is a pressure detector, 31 is a pressure control valve, and 33 is a pressure control circuit (pressure control device). Represents

A silicon wafer 1, which is a workpiece, is held by being attracted to the upper surface of a turntable 2. The turntable 2 is attached to an upper end of the drive shaft 3.
A polishing head 5 is disposed above the turntable 2, and a polishing agent supply nozzle 4 is disposed adjacent to the polishing head 5.

The polishing head 5 includes a pressing mechanism 17, a main shaft 9, a drive motor 10, a ball screw 29, and a servo motor 2.
7, a ball screw 29, a coupling 2
8 and a servo motor 27, which are attached below the turning arm 12. Further, the polishing head 5 is supported from the side by the guide mechanism 8 and can move up and down along the guide mechanism 8. The guide mechanism 8 is also attached below the turning arm 12. The pressing mechanism 17 is provided above the turntable 2
The polishing pad 20 is mounted on the lower surface of the pressing mechanism 17. Here, the diameter of the effective polishing surface of the polishing pad 20 is smaller than the diameter of the silicon wafer 1.

Using a servo motor 27, a ball screw 29
, The polishing head 5 moves vertically along the guide mechanism 8. By driving the drive motor 10, rotation is given to the pressing mechanism 17 via the main shaft 9. Also, by controlling the pressure of the working fluid (generally using air) supplied to the pressurizing mechanism 17 via the pressure control valve 31 or the like, the polishing of the silicon wafer 1 is performed as described later. The pressing force of the cloth 20 can be kept constant.

FIG. 2 shows the details of the pressing mechanism 17. The holder 22 has a substantially columnar shape, and a hollow portion (working fluid chamber 41) is formed at the center of the lower end of the holder 22.
A screw portion is formed on the outer peripheral surface of the lower end. A cap 21 in the shape of a cap nut is attached to the screw portion. A circular opening 21 a is formed in the center of the cap 21. The polishing pad 20 is attached to the holder 22 by fixing the polishing pad 20 between the peripheral part of the lower end surface of the holder 22 and the inner surface of the cap 21 with the peripheral part sandwiched therebetween.

The polishing cloth 20 is made of an elastic body (in this example, a polyurethane sheet), has an axially symmetrical three-dimensional shape, and has a hollow having a cylindrical side wall 20a and a flat bottom 20b at the center thereof. Are formed. This depression is
The cap 21 protrudes below the cap 21 through an opening 21a in the center of the cap 21, and the bottom 20b is
And the side wall 20a is in contact with the inner periphery of the opening 21a. Inside of the depression (back side of polishing cloth 20)
A working fluid chamber 41 in which a working fluid is accommodated is formed by the hollow portion and an outer peripheral surface near an upper end portion of the holder 22 which is configured so that the pressure of the working fluid directly acts on the inside of the recess. A circumferential groove 43 is formed. This groove 43 is connected to the working fluid chamber 41 via a through hole 45. The ring-shaped rotary joint 23 is attached so as to cover the groove 43 from the outside. The space between the outer circumferential surface of the holder 22 and the inner circumferential surface of the rotary joint 23 is sealed by an O-ring 24a above the groove 43 and by an O-ring 24b below the groove 43, respectively. The holder 22 can rotate inside the rotary joint 23. The working fluid hose 18 is connected via a joint 25 to the center of the rotary joint 23 in the height direction.

The working fluid is a working fluid hose 18, a groove 4
It is sent into the working fluid chamber 41 through the through hole 3 and the through hole 45 in order. By applying pressure to the working fluid in the working fluid chamber 41, the bottom portion 20 b of the polishing cloth is pressed against the surface of the silicon wafer 1.

As shown in FIG. 1, the working fluid supply system into the working fluid chamber 41 includes a working fluid hose 18, a pressure detector 30, a pressure control valve 31, and a working fluid supply pump 3.
2 and a pressure control circuit 33. The pressure of the working fluid supplied into the working fluid chamber 41 via the working fluid hose 18 is detected by the pressure detector 30;
The output of the pressure detector 30 is sent to the pressure control circuit 33,
The pressure control circuit 33 performs feedback control of the opening of the pressure control valve 31 so that the supply pressure of the working fluid is maintained at a preset value.

FIG. 3 shows the polishing cloth 2 when the position of the polishing head 5 changes in the vertical direction with respect to the silicon wafer 1.
0 shows a state of deformation. As shown in FIG. 3, when the distance from the silicon wafer 1 to the polishing head 5 is changed, the pressure of the working fluid causes the side wall portion 20a of the polishing cloth to be elastically deformed, and the polishing cloth from the opening 21a of the cap 21 to be removed. 20
Changes the amount of protrusion. This absorbs vertical position fluctuations of the polishing head 5.

As described above, even if a slight change occurs in the vertical position of the polishing head 5 with the movement of the swing arm 12, the polishing pad 20 is elastically deformed.
The pressing force of the polishing pad 20 against the silicon wafer 1 can be kept constant. Therefore, the CMP of the present invention
According to the apparatus, the processing amount in the surface to be polished can be kept uniform.

In the above configuration, since high rigidity is not required for the revolving arm 12 in order to secure in-plane uniformity of the machining amount, the size and weight of the device can be reduced.

FIG. 4 shows another example of the CMP polishing apparatus according to the present invention. In this example, a gate-shaped linear moving mechanism 15 is used instead of the turning arm 12 (FIG. 1) in the previous example. The polishing head 5 is attached below the linear moving mechanism 15. Other configurations are the same as those in the previous example, and thus the same reference numerals are given and the description will be omitted.

[0023]

According to the CMP polishing apparatus of the present invention, when polishing a large-sized flat plate-shaped workpiece using a polishing tool having a smaller area than the surface to be polished, the polishing head is removed from the surface to be polished. The pressing force of the polishing tool against the surface to be polished can be kept constant even when the distance to the surface varies.
Therefore, high accuracy can be achieved for the uniformity of the processing amount in the surface to be polished.

Further, since the fluctuation of the distance from the surface to be polished to the polishing head can be absorbed by the movement of the polishing surface, the rigidity of the structure supporting the polishing tool can be reduced, and the apparatus can be miniaturized.・ Effective for weight reduction.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a CMP apparatus according to the present invention.

FIG. 2 is a sectional view showing details of a pressurizing mechanism of the CMP apparatus according to the present invention.

FIG. 3 is a cross-sectional view for explaining the movement of a pressing mechanism accompanying the vertical movement of the polishing head.

FIG. 4 is a diagram showing another example of the CMP apparatus according to the present invention.

FIG. 5 is a diagram showing an example of a conventional CMP apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon wafer (workpiece), 2 ... Turntable, 3 ... Drive shaft, 4 ... Abrasive supply nozzle, 5 ... Polishing head, 6 ... Polishing cloth, 7 ... top ring, 8 ... guide mechanism, 9 ... spindle, 10
... Driving motor, 11 ... Air cylinder, 12 ...
• Revolving arm (moving means), 15: linear moving mechanism (moving means), 17: pressurizing mechanism, 18: working fluid hose, 20: polishing cloth (polishing tool), 20a
... side wall part, 20b ... bottom part, 21 ... cap, 21a ... opening part, 22 ... holder, 23 ...
.Rotary joints, 24a, 24b... O-ring, 25.
・ Coupling, 27 ・ ・ ・ Servo motor, 28 ・ ・ ・ Coupling, 29 ・ ・ ・ Ball screw, 30 ・ ・ ・ Pressure detector,
31 pressure control valve, 32 working fluid supply pump, 33 pressure control circuit (pressure control device), 41
... working fluid chamber (cavity), 43 ... groove, 45 ...
-Through holes.

Claims (3)

[Claims] 1. A turntable on which a flat plate-shaped workpiece is held, and a polishing tool having a smaller area than a surface to be polished of the workpiece are mounted, and the polishing tool is rotated and driven. A CMP polishing apparatus comprising: a polishing head that presses a polishing tool against a surface to be polished by the pressure of a working fluid; and a moving unit that moves the polishing head in a plane parallel to the surface to be polished. And a pressure controller that feedback-controls the pressure of the working fluid so that the pressure detected by the detector matches a preset value. C
MP polishing equipment. 2. The polishing tool according to claim 1, wherein the polishing tool is a polishing cloth made of an elastic material, and the pressure of the working fluid directly acts on a back surface of the polishing cloth. The CMP apparatus according to claim 1. 3. The polishing tool is a polishing cloth made of an elastic body, and has a hollow having a cylindrical side wall and a flat bottom formed at the center thereof, and a pressure of the working fluid inside the hollow. The CMP apparatus according to claim 1, wherein the CMP apparatus is configured to operate directly.