JP2000042901A - Polishing cloth and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polishing cloth causing no difference in a polishing quantity between the peripheral part and the central part, having the long service life and being efficiently usable by constituting the polishing cloth of a urethane foam member, and regularly arranging long pores in large numbers in this. SOLUTION: Polishing cloth 1 for chemical mechanical polishing is composed of a hard urethane foam member 3, and for example, elliptic long pores 2 are regularly arranged in large numbers in a radial shape. In polishing a semiconductor wafer, the polishing cloth 1 is installed on a surface plate to press the semiconductor wafer. Since the long pores 2 are arranged in large numbers in a radial shape in the horizontal direction on the polishing surface in the polishing cloth 1, a lateral directional flow of an abrasive is promoted so as to efficiently perform supply of the abrasive and the replacement of a reaction product without forming a separate passage in the polishing cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing cloth used for chemical mechanical polishing and the like and a method for manufacturing the same, and more particularly, to a polishing cloth with high polishing efficiency and a long life, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Chemical and mechanical polishing (CMP) is used for polishing the surface of a large-diameter 300 mm semiconductor wafer that requires ultra-high flatness and high purity.
g) or mechanochemical polishing (hereinafter referred to as CMP) is indispensable. The CMP is a method in which a polishing liquid is provided with the ability to chemically etch the material to be polished, and at the same time, the material is polished mechanically by particles contained in the polishing liquid.

As shown in FIG. 9, a polishing apparatus 20 generally used for CMP has a platen 22 having a water passage 21 for cooling water c, and a urethane polishing cloth 23 attached to the platen 22 as shown in FIG. On the other hand, a semiconductor wafer W as a member to be polished is pressed against the polishing cloth 23. This semiconductor wafer W is mounted on a mount plate 25 by wax 24.
The mount plate 25 is attached to a head 26 which is pressurized in the direction of the surface plate 22 and variably rotates.

[0004] A supply pipe 28 for constantly supplying an abrasive 27 to the polishing cloth 23 is provided. In the polishing process of the semiconductor wafer W by the CMP using the polishing apparatus 20 as described above, the mount plate 25 and the platen 2
2 are rotated together, the mount plate 25 is lowered, and the surface of the semiconductor wafer W is brought into contact with the polishing pad 23 on the surface plate 22 and pressed. In this polishing step, it is important to optimize the balance between the etching amount of the chemical polishing and the pressurization of the mechanical polishing in consideration of the surface state of the semiconductor wafer W, and the polishing amount of the chemical polishing depends on the type of the polishing liquid. , PH, composition, etc., and the amount of mechanical polishing is determined by conditions such as the type and concentration of particles contained in the abrasive, polishing cloth, pressure, rotation speed, rotation direction, and the like.

However, in setting such conditions,
Abrasive 27 easily accumulates in central portion 23c of polishing cloth 23,
There is a problem that the polishing amount varies within the same semiconductor wafer W or between the semiconductor wafers W.

The polishing pad 23 made of urethane is polished while holding the polishing agent by a foamed structure.
7 has a limited holding capacity, and it is not easy to replace a reaction product generated by polishing.
There have been problems such as shortening of the life of the polishing cloth due to occurrence of clogging of the polishing cloth.

Therefore, in order to solve the above problems,
Japanese Patent Application Laid-Open No. 7-321076 discloses a polishing cloth 30 as shown in FIG. 10, which has a thickness of several mm.
A fan-shaped polishing pad 32 of a fan shape having a thickness of about 1 mm is adhered to the surface of the urethane base material 31 of each of the polishing pads 32.
Channel grooves 33 for multiple abrasives 27 are formed radially between them. The abrasive 27 flows from the central portion 30 c of the surface plate 22 to the peripheral portion 30 p through the flow channel groove 33 due to the centrifugal force generated by the rotation of the surface plate 22.
The polishing agent 27 is efficiently supplied also to the peripheral portion 30p without a large amount of the polishing agent 27 accumulating at 0c, thereby solving the problem that a difference in polishing amount occurs between the peripheral portion 30p and the central portion 30c.

Further, in order to solve the problem that the difference in the amount of polishing occurs between the peripheral portion and the central portion 23c of the polishing pad 23, Japanese Patent Application Laid-Open No. 7-321076 described above, as shown in FIG. Disclosed is a polishing cloth 35 in which a number of polishing pads 38 are adhered to the surface of a urethane base material 37 so as to form a radial shape in which the 36 is curved in a certain direction. Further, in the polishing cloths 30 and 35 shown in FIGS. Timber 31,
One in which the polishing pad 37 and the polishing pads 32 and 38 are integrally formed is disclosed.

[0009] The polishing cloths 30 and 35 of the present disclosure have a peripheral portion 3.
It is possible to solve the problem that the difference in the amount of polishing occurs between 0p and 35p and the center portions 30c and 35c.
Since the flow grooves 33 and 36 are formed on the surface of 35, damage may occur from the peripheral portions of the flow grooves 33 and 36 during the polishing process. Peripheral parts 30p, 36p of polishing cloths 30, 36 with a large amount of abrasive 27
Therefore, a large amount of the abrasive 27 is used, which is uneconomical.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and there is no difference in the amount of polishing between the peripheral portion and the central portion. It is an object of the present invention to provide a possible polishing cloth and a method for manufacturing the same.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a polishing cloth characterized by comprising a urethane foam member having a large number of regularly arranged long pores. It is a gist.

According to the invention of claim 2 of the present application, the long pores are arranged radially, and the gist is that the polishing pad is the polishing cloth according to claim 1.

In the invention of claim 3 of the present application, the long pores are arranged radially in a direction curved in a direction opposite to the rotation direction of the polishing cloth, and the gist is that of the polishing cloth according to claim 1. .

According to a fourth aspect of the present invention, there is provided a polishing cloth according to any one of the first to third aspects, wherein a plurality of the urethane foam members are laminated.

The polishing cloth according to any one of claims 1 to 4, wherein a plurality of urethane foam members are laminated with the direction of the long pores shifted in the invention according to claim 5 of the present application. The gist is that.

In the polishing cloth according to claim 1, the urethane foam in which the long pores are linearly arranged in one direction is laminated with the direction of the long pores shifted. The gist is that there is.

According to a seventh aspect of the present invention, there is provided a step of preparing a urethane foaming mold, a step of supplying a urethane foaming material to the foaming mold, and a step of applying a centrifugal force to the urethane foaming material during foaming of the urethane foaming material. And a step of slicing the foamed urethane member that has completed foaming.

The invention of claim 8 of the present application is a step of foaming a urethane foam raw material to form a urethane sheet, a step of applying a tensile stress to the urethane foam sheet in a linear direction at the time of foaming the urethane foam sheet, And a step of punching out the cured urethane foam sheet to the size of a polishing cloth.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a polishing cloth and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, a polishing cloth, for example, a polishing cloth for chemical mechanical polishing 1 has a disk shape, for example, a thickness t of 5 mm, and is made of a hard urethane foam member 3 and regularly. An array, for example, is provided with a large number of elongated pores 2 which are arranged radially and are oblong in plan view.

Next, a method of manufacturing the polishing pad 1 for chemical mechanical polishing will be described with reference to FIG.

A urethane foam stock solution M is supplied to a split foaming mold 6 having a cylindrical plug 5 provided on a rotating shaft 4 driven by a motor and heated and foamed. At the same time as the foaming starts, the foaming mold 6 is rotated via the rotating shaft 4 by the motor drive, and the centrifugal force acts on the urethane foam solution M to grow the long pores 2 generated in the urethane foam member 3 long and radially. . After cooling, the foaming mold 5 is divided, the urethane foam member 3 is taken out, sliced, formed into a polishing cloth 1 shape, and a number of long pores 2 are arranged radially in a direction parallel to the polishing surface. A polishing cloth 1 having the following is obtained.

The polishing cloth 1 may be formed integrally by attaching a urethane foam member (urethane pad) having a thickness of about 1 mm to a urethane base material having a thickness of about several mm.

The polishing of a semiconductor wafer W by CMP using the polishing cloth 1 according to the present invention in a polishing apparatus 20 as shown in FIG. 9 will be described.

The polishing cloth 1 is mounted on a surface plate 22 having a water passage 21 for the cooling water W of the polishing apparatus 20, and the semiconductor wafer W is brought into pressure contact with the polishing cloth 1. The semiconductor wafer W is detachably fixed to a mount plate 25 by wax 24. The mount plate 25 is pressurized in the direction of the surface plate 22 and is attached to a head 26 that rotates variably.

An abrasive 2 is supplied to the polishing cloth 1 from a supply pipe 28.
7 is constantly supplied, and the semiconductor wafer W is subjected to CMP polishing by chemical polishing by the abrasive 27 and mechanical polishing by particles contained in the abrasive, but the polishing cloth 1 is coated with the abrasive 27 as shown in FIG. Since a large number of long pores 2 are arranged radially in a horizontal direction with a direction parallel to the polishing surface to contribute to the retention, and are arranged in a large number, the flow of the abrasive in the lateral direction (radial direction) is promoted. The polishing agent can be efficiently supplied and the reaction product can be replaced without separately forming grooves for the flow path in the polishing cloth, and the polishing can be efficiently performed under the optimum condition. Clogging can be prevented.

Furthermore, a separate groove for the flow path is not required, so that the breakage of the groove for the flow path does not occur during the polishing process to shorten the life of the polishing pad. A large amount of the abrasive does not flow to the peripheral portion of the polishing cloth, so that the abrasive can be used effectively and is economical.

Next, a second embodiment will be described.

As shown in FIG. 5, the polishing pad 10 for chemical mechanical polishing has a disk shape and a thickness of, for example, 2 mm.
A plurality of hard urethane foam members (urethane pads) 12 having a large number of long pores 11 arranged radially, e.g.
It is configured by being laminated.

The three urethane foam pads 12a, 12
Since the long pores 11a, 11b, 11c are present at different positions from each other, the long pores 11a, 11b,
It is not always necessary to shift the arrangement direction of 11b and 11c, but by shifting each of them, more effective use of the abrasive can be expected.

This polishing pad 10 for chemical mechanical polishing is formed by laminating urethane foam pads 12 so that the long pores 11 of the urethane foam pads 12 of each layer communicate with each other, so that the flow of the abrasive 13 is not only in the radial direction but also in the depth direction. It is secured in the direction, that is, it is secured not three-dimensionally but three-dimensionally, so the amount secured is increased, and the replacement efficiency of the polishing agent, which was limited with a simple polishing cloth made of urethane foam, is a nonwoven bonded polishing cloth. A polishing cloth 1 which is inexpensive and is less expensive than a nonwoven bonded polishing cloth can be obtained. Further, it is possible to manufacture a polishing cloth that maintains the hardness for realizing high flatness of the semiconductor wafer W.

Next, a third embodiment will be described.

As shown in FIG. 6, the polishing pad 14 for chemical mechanical polishing has a desk shape and a thickness of, for example, 2 mm.
A plurality of, for example, three hard urethane foam members (urethane pads) 16 having many long pores 15 arranged in parallel with the center line of the book are laminated. The center lines of the urethane foam pads 16a, 16b, 16c of each layer have an angle of 120 degrees, respectively, and the long pores 15a, 15b, 15c, of the urethane foam pads 16a, 16b, 16c of each layer,
15c are also arranged at an angle of 120 degrees.

The abrasive cloth 14 for chemical mechanical polishing is manufactured by applying a tensile stress in the longitudinal direction of the urethane foam sheet 17 during the production of the urethane foam sheet 17 as shown in FIG. Punch according to. The urethane pad 16 manufactured in this manner is inferior to the abrasive flow of the first and second embodiments in terms of the promotion of the flow of the abrasive, but the direction of the long pores is small. By laminating a plurality of sheets by shifting the properties, the promotion of the flow of the abrasive can be improved, and there is an advantage that the polishing cloth can be manufactured at low cost.

Next, a fourth embodiment will be described.

As shown in FIG. 8, the direction of the long pores 18 is radially arranged in a direction opposite to the rotation direction of the polishing pad 19 for chemical mechanical polishing. A large number of long pores 19 are arranged radially in a horizontal direction with a direction parallel to the polishing surface so as to contribute to holding of the abrasive, and a large number of long pores 19 are arranged using the directionality of centrifugal force. , The supply of the abrasive and the replacement of the reaction product can be performed efficiently, the polishing can be performed efficiently under the optimum conditions, and the clogging of the polishing cloth can be prevented.

[0037]

The polishing cloth and the method of manufacturing the same according to the present invention use a polishing cloth made of a urethane foam member having a large number of regularly arranged long pores to polish the periphery and the center of a semiconductor wafer. There is no difference in quantity,
Provided is a polishing cloth which has a long life and allows efficient use of an abrasive, and a method for producing the same.

Further, since the long pores are arranged radially, the flow of the abrasive in the lateral direction can be more effectively promoted, and the supply of the abrasive and the replacement of the reaction product can be performed efficiently. Polishing can be performed efficiently under the conditions, and clogging of the polishing cloth can be prevented.

Further, since the long pores are radially arranged in a curved direction in a direction opposite to the direction of rotation of the polishing pad, the abrasive can be made to flow more effectively in the lateral direction by utilizing the directionality of centrifugal force.
The supply of the abrasive and the replacement of the reaction product can be performed efficiently, the polishing can be performed efficiently under the optimum conditions, and the clogging of the polishing cloth can be prevented.

Further, the polishing cloth is formed by laminating a plurality of urethane foam members having long pores linearly arranged in one direction while shifting the direction of the long pores. In addition, there is an advantage that the polishing cloth can be manufactured at a low cost.

Furthermore, since a plurality of urethane foam members are laminated, the amount of the abrasive is secured not three-dimensionally but three-dimensionally on the polishing cloth. The replacement efficiency of the abrasive is comparable to that of the nonwoven bonded polishing cloth, and a polishing cloth which is less expensive than the nonwoven bonded polishing cloth can be obtained.

Further, it is possible to manufacture a polishing cloth which maintains the hardness for realizing a high flatness of the semiconductor wafer.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a polishing cloth according to the present invention.

FIG. 2 is a cross-sectional view of the first embodiment of the polishing pad according to the present invention shown in FIG. 1;

FIG. 3 is an explanatory view showing a method for manufacturing the polishing pad according to the first embodiment of the present invention shown in FIG. 1;

FIG. 4 is an explanatory view showing a state when the polishing pad according to the first embodiment of the present invention shown in FIG. 1 is used.

FIG. 5 is an explanatory view showing a state in which a polishing pad according to a second embodiment of the present invention is used.

FIG. 6 is a plan view of a polishing cloth according to a third embodiment of the present invention, with a portion cut away.

FIG. 7 is an explanatory view showing a method for manufacturing a polishing pad according to a third embodiment of the present invention shown in FIG. 6;

FIG. 8 is a sectional view of a polishing pad according to a fourth embodiment of the present invention.

FIG. 9 is an explanatory view of a generally used polishing apparatus.

FIG. 10 is a plan view in which a part of a conventional polishing cloth is cut away.

FIG. 11 is a plan view in which a part of another conventional polishing pad is cut away.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 polishing cloth (polishing cloth for chemical mechanical polishing) 2 long pores 3 urethane member 4 rotating shaft 5 plug 6 foam type 10 polishing cloth (polishing cloth for chemical mechanical polishing) 11 long pores 12 urethane foam member (urethane pad) 13 abrasive 14 polishing cloth (polishing cloth for chemical mechanical polishing) 15 long pores 16 urethane foam member (urethane pad) 17 urethane foam sheet 18 long pores 19 polishing cloth (polishing cloth for chemical mechanical polishing)

Claims (8)

[Claims] 1. A polishing cloth comprising a urethane foam member having a large number of regularly arranged long pores. 2. The polishing cloth according to claim 1, wherein the long pores are arranged radially. 3. The polishing pad according to claim 1, wherein the long pores are arranged radially in a direction curved in a direction opposite to a rotation direction of the polishing pad. 4. The polishing cloth according to claim 1, wherein a plurality of the urethane foam members are laminated. 5. The urethane foam member according to claim 1, wherein a plurality of urethane foam members are stacked with the direction of the long pores shifted.
5. The polishing cloth according to any one of items 4 to 4. 6. The polishing cloth according to claim 1, wherein the urethane foam in which the long pores are linearly arranged in one direction is laminated with the long pores shifted in direction. 7. A step of preparing a foaming urethane foaming mold, a step of supplying a urethane foaming raw material to the foaming mold,
A method for producing a polishing cloth, comprising: a step of applying a centrifugal force to the urethane foam material at the time of foaming the urethane foam material; and a step of slicing the foamed urethane member after foaming. 8. A step of foaming the urethane foam material to form a urethane sheet, a step of applying a tensile stress to the urethane foam sheet in a linear direction during the foaming of the urethane foam sheet, and a step of curing the urethane foam sheet. Punching out the cured urethane foam sheet to the size of a polishing cloth.