JP2003133272A - Cmp apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP apparatus that allows adjusting disposition patterns of a plurality of air holes in a relatively simple manner such that they are placed in locations enabling a desired pressure distribution to be formed. SOLUTION: The CMP apparatus comprises a wafer holding unit 101 which absorbs a semiconductor wafer 5 via a plurality of air holes 4 that are provided on a stage 2 for holding the semiconductor wafer 5 and a pad 3. After the semiconductor wafer 5 abuts to a rotary table, pressurized gas is fed through the air holes 4 to press the semiconductor wafer 5 and the rotary table with predetermined pressure, and the apparatus polishes the semiconductor wafer 5. The pad 3 is adhered to the stage 2 via a pressure adjusting mask 102 which is formed with openings 103 having patterns for blocking predetermined air holes 4b to control the pressure distribution of the pressurized gas to be applied to the semiconductor wafer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP apparatus, and more particularly to a CMP apparatus capable of improving the uniformity of polishing corresponding to an object to be processed having unique polishing characteristics for each product.

[0002]

2. Description of the Related Art Conventionally, for example, as a device for polishing the surface of a semiconductor wafer, a CMP device for improving the polishing processing accuracy by pressing the semiconductor wafer against a rotating table with a pressure gas at a uniform pressure. Is used.

An example of a wafer holder portion of a conventional CMP apparatus will be described with reference to FIG. 3 (a) showing a cross-sectional view of an essential part and FIG. 3 (b) showing a plan view. However, FIG. 3 (a)
FIG. 4B is a cross-sectional view taken along line XX in FIG. 3B, showing a state in which the semiconductor wafer is held. As shown in FIG. 3A, a pad 3 is attached to the back surface of the stage 2 of the wafer holder unit 1. Further, the stage 2 and the pad 3 are provided with a plurality of ventilation holes 4 penetrating both. The vent hole 4 has both a function as a suction hole for vacuum-sucking the semiconductor wafer 5 on the pad 3 and a function as a pressure gas supply hole for pressing the semiconductor wafer 5 against a rotary table (not shown). is doing. Where the vent hole 4
The reason for providing a large number (for example, 147) is to improve the polishing processing accuracy by pressing the semiconductor wafer 5 against the rotary table (not shown) with a pressure gas at a uniform pressure. Further, these ventilation holes 4 are connected to a common void portion 6, and the upper wall portion of the stage 2 sucks gas in the void portion 6 or supplies pressurized gas into the void portion 6. A connecting portion 8 having a ventilation portion 7 for forming is formed, and the connecting portion 8 is connected to a pump 9 that sucks or supplies gas. Incidentally, as shown in FIG.
The plurality of ventilation holes 4 are, for example, evenly arranged on the circumference of concentric circles having different radii from the center of the stage 2. This is because the surface of the semiconductor wafer 5 is uniformly attracted or pressed. A holding ring 10 is attached to the end faces of the stage 2 and the pad 3 so as to surround them. The holding ring 10 slightly projects downward from the surface of the pad 3, and the holding ring 10 holds the peripheral end surface of the semiconductor wafer 5.
In this way, the wafer holder unit 1 of the CMP apparatus is configured.

When polishing the semiconductor wafer 5, first, the semiconductor wafer 5 is put into the holding ring 10 of the wafer holder 1, and then the pump 9 is operated to suck the gas in the wafer holder 1. As a result, the inside of the void portion 6 becomes a vacuum, and the semiconductor wafer 5 is vacuum-sucked to the pad 3 serving as a holding surface of the semiconductor wafer 5. Next, the wafer holder part 1 conveys the semiconductor wafer 5 onto a rotary table (not shown) in a state where the semiconductor wafer 5 is sucked, and brings the surface to be polished into contact with the rotary table (not shown). Next, the pump 9 is operated to supply the pressure gas, so that the semiconductor wafer 5 is pressed against the surface of the rotary table (not shown) at a predetermined pressure, and is rotated while supplying the polishing agent (not shown). A table (not shown) is rotated to subject the surface to be polished to CMP. After that, the pump 9 is again operated so as to suck the gas in the wafer holder portion 1, so that the semiconductor wafer 5 is adsorbed on the surface of the pad 3 and conveyed to a predetermined position. Of course, the pump for sucking the gas and the pump for supplying the pressure gas may be configured to use different pumps.

[0005]

As described above, a large number of ventilation holes are provided on the holding surface of the conventional CMP apparatus, and all the ventilation holes communicate with each other through a common space to supply the pressure gas. At this time, the object to be treated is pressed with a uniform pressure through each vent hole. However, in an actual object to be processed, for example, a semiconductor wafer, a composite factor such as the unevenness of the surface due to the wiring pattern, the size and thickness of the semiconductor wafer, the difference in the nature and hardness of the film type formed on the surface to be polished, etc. Therefore, in the polishing rate between the outer peripheral portion and the central portion of the semiconductor wafer, there is a deviation peculiar to the product,
Pressing the object to be treated with a uniform pressure distribution over the entire surface was not always optimal for obtaining a uniform film pressure. Therefore, it is necessary to change the arrangement pattern of the vent holes so that the polishing characteristics (habit) peculiar to the product of the object to be processed are offset so that the pressure distribution can be finely adjusted.

The present invention has been made in view of the above problems, and is a CMP in which the arrangement pattern of a plurality of vent holes can be adjusted by a relatively simple method to an arrangement capable of forming a desired pressure distribution. The purpose is to provide a device.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, in which an object to be processed is adsorbed through a plurality of ventilation holes provided in a holding surface and brought into contact with a rotary table. After that, while supplying a pressure gas through the ventilation hole and pressing it against the rotary table at a predetermined pressure, the rotary table is rotated, and in the CMP apparatus for polishing the surface to be polished, there is a means for closing the predetermined ventilation hole, A CM characterized in that the pressure distribution of the pressure gas applied to the object to be processed can be adjusted.
P device.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a wafer holder portion of a CMP apparatus according to the present invention is shown in FIG.
Also, description will be given with reference to FIG. 1B shown as a plan view.
However, FIG. 1A is a cross-sectional view taken along the line YY of FIG. 1B and shows a state in which the semiconductor wafer is held.
The same parts as those in FIG.
The wafer holder portion 101 of the CMP apparatus of the present invention is shown in FIG.
As shown in (a), unlike the conventional wafer holder unit 1, the pad 3 is attached to the back surface of the stage 2 of the wafer holder unit 101 via a pressure adjustment mask 102 made of, for example, synthetic resin. It is a point. The pressure adjusting mask 102 has an opening 103 that allows only a predetermined vent hole 4a among the many vent holes 4 provided in the stage 2 and the pad 3 to vent, and closes the other vent holes 4b. It is formed in an arrangement pattern corresponding to the ventilation holes 4a. That is, by covering the stage 2 or the pad 3 with the pressure adjustment mask 102, the arrangement pattern of the ventilation holes 4 can be changed in the direction in which the ventilation holes 4 are reduced, and the pressure distribution for pressurizing the semiconductor wafer 5 with the pressure gas can be adjusted. It will be possible. The opening 103 has a size larger than that of the vent hole 4a, and the stage 2 and the pressure adjustment mask 1
02 and the pad 3 are preferably arranged so as to facilitate the work of aligning the holes. The material of the pressure adjusting mask 102 is not particularly limited, and may be plastic resin or metal such as stainless steel as long as it has good workability and durability. In advance
An experiment for condition setting is performed, and several kinds of pressure adjustment masks 102 having an optimum opening pattern are prepared for each product.
Replace each product to obtain the optimum pressure distribution for that product. For example, in a product in which the polishing rate of the outer peripheral portion becomes faster when pressed with a uniform pressure, a pressure adjustment mask having an opening pattern formed to block some of the ventilation holes 4 in the outer peripheral portion as shown in FIG. By applying 102, the pressing force of the outer peripheral portion is suppressed and the imbalance of the polishing rate with the central portion is corrected. On the contrary, in the case of a product having a high polishing rate in the central portion, a pressure adjusting mask (not shown) having an opening pattern for closing some of the vent holes 4 in the central portion is applied. However, the vent hole 4 is formed by connecting the semiconductor wafer 5 to the pad 3
Since it also has a function as an adsorption hole for adsorbing to, it is necessary to keep the adsorption capacity so that it does not deteriorate.

When polishing the semiconductor wafer 5, first, a predetermined pressure adjusting mask 102 suitable for the product to be polished is selected, and the pad 3 is attached to the stage 2 via the pressure adjusting mask 102. By doing so, the pressure distribution in which the pressure gas pressurizes the semiconductor wafer 5 through the ventilation hole 4a during polishing is adjusted to a desired pressure distribution. Incidentally, the decrease in the number of the ventilation holes 4 is limited to the extent that an adsorption error does not occur during adsorption. Then, the semiconductor wafer 5 is placed in the holding ring 10, the pump 9 is operated, and the gas in the wafer holder portion 101 is sucked.
As a result, the inside of the void 6 becomes a vacuum, and the semiconductor wafer 5 is vacuum-sucked to the pad 3. Next, the wafer holder unit 101 conveys the semiconductor wafer 5 onto a rotary table (not shown) in a state where the semiconductor wafer 5 is sucked, and brings the surface to be polished into contact with the rotary table (not shown). next,
By operating the pump 9 and supplying pressure gas, the semiconductor wafer 5 is pressed against the surface of the rotary table (not shown), and the rotary table (not shown) is moved while supplying the polishing agent (not shown). The surface to be polished is rotated and subjected to CMP processing. After that, the pump 9 is again operated so as to suck the gas in the wafer holder portion 101, so that the semiconductor wafer 5 is adsorbed on the surface of the pad 3 and conveyed to a predetermined position. Of course, the pump for sucking the gas and the pump for supplying the pressure gas may be configured to use different pumps.

In the above description, the stage or pad having the ventilation holes is covered with a mask having a predetermined opening pattern. However, for example, silicon is molded into a shape that closes each ventilation hole, and is molded. The silicon may be pressed into individual air holes to obtain the desired air hole layout pattern, but the mask method is easier to replace and the human does not forget to put the silicon in or put it in incorrectly. This is preferable because the potential for error can be reduced.

[0011]

According to the CMP apparatus of the present invention, the arrangement pattern of the ventilation holes can be adjusted by the pressure adjusting mask, and as a result, the pressure distribution for pressurizing the object to be polished can be adjusted.
It is possible to correct the difference in polishing rate within the surface to be polished peculiar to the product and improve the uniformity of polishing. Further, by using the mask type pressure adjusting means, the mask replacement work at the time of product switching can be facilitated and the potential for human error can be reduced. Further, if the size of the opening of the pressure adjustment mask is made larger than the size of the ventilation hole, it is preferable that the position adjustment work when covering the holding surface with the pressure adjustment mask can be facilitated.

[Brief description of drawings]

FIG. 1 is a sectional view and a plan view of an essential part of an example of a wafer holder part of a CMP apparatus according to the present invention.

FIG. 2 is a plan view of a pressure adjustment mask.

FIG. 3 is a cross-sectional view and a plan view of an essential part of a wafer holder portion of a conventional CMP apparatus.

[Explanation of symbols]

2 stages 3 pads 4 ventilation holes 5 Semiconductor wafer 101 Wafer holder part 102 Pressure adjustment mask 103 opening

Claims (3)

[Claims] 1. An object to be treated is adsorbed through a plurality of ventilation holes provided on a holding surface, brought into contact with a rotary table, and then pressurized gas is supplied through the ventilation holes to press the rotary table at a predetermined pressure. At the same time, a CMP apparatus for rotating a rotary table to polish a surface to be polished has means for closing a predetermined vent hole, and is capable of adjusting a pressure distribution of a pressure gas applied to an object to be processed. CMP equipment. 2. A means for closing a predetermined vent hole is a pressure adjusting mask having an opening pattern for opening a part of the vent hole to be vented and covering the part of the vent hole to be closed. The CMP apparatus according to claim 1. 3. The CMP apparatus according to claim 2, wherein the size of the opening formed in the pressure adjustment mask is larger than the size of the ventilation hole.