KR20030059638A - Chemical mechanical polishing apparatus with a polishing head - Google Patents

Abstract

The present invention relates to an apparatus for chemically and mechanically polishing a surface of a semiconductor wafer. According to the present invention, a supporter of the polishing head has posts protruding from a bottom surface and having vacuum holes formed therein, and a cap covering the posts. It has a back film of a shape. Therefore, the back film is not pushed due to the rotational force of the polishing head and the pressure of the membrane during the polishing process, thereby preventing the problem of blocking the vacuum hole of the supporter.

Description

Chemical Mechanical Polishing Equipment with Polishing Head {CHEMICAL MECHANICAL POLISHING APPARATUS WITH A POLISHING HEAD}

The present invention relates to an apparatus for manufacturing a semiconductor wafer, and more particularly to an apparatus for chemically and mechanically polishing a surface of a semiconductor wafer.

In recent years, as semiconductor devices have been highly integrated, wiring structures have been multilayered to increase the surface level difference between the unit cells stacked on the semiconductor substrate, and various methods of polishing the wafer process surface have been proposed to reduce the surface level difference between the unit cells. It is becoming. Among them, CMP (Chemical Mechanical Polishing) equipment for flattening the process surface of the wafer which simultaneously chemically polishes the wafer is widely used.

Typically, in a CMP process, a wafer is mounted to a polishing head with its process surface facing the turn table, and the process surface of the wafer is placed on a turntable provided with a polishing pad.

As shown in FIG. 1, a conventional polishing head 100 includes a carrier 102 having a gas outlet and a retainer ring 104 and a wafer installed at the bottom edge of the carrier 102 and providing space for supporting the wafer. And a membrane 106 of flexible material facing away from the substrate. The bottom of the polishing head 100 is provided with a plurality of supporter holes 108 for adsorbing the wafer or applying pressure to the wafer.

FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1 of a conventional polishing head loaded with a wafer. As shown, the polishing head provides a controllable pressing force or pressure on the wafer to press the wafer against the polishing pad of the turntable. The supporter 110 is installed in the carrier 102 of the polishing head 100. The supporter 110 has a chamber 112 communicating with the gas inlet 132, and supporter holes 120 communicating with the chamber 112 are installed at a bottom of the supporter 110. In the polishing head of the conventional chemical mechanical polishing apparatus, the spotter holes 120 exist in the post 116 protruding from the bottom of the supporter 110. Since the post 116 is in direct contact with the wafer, it is attached to the bottom surface of the post 116, which is a medium for applying pressure to or adsorbing the wafer. The membrane 114 surrounds the bottom of the supporter 110.

As shown in FIG. 3, the conventional polishing head 100 has the back film 118 at the bottom of the post 116 having a narrow area. Accordingly, the back film 118 is pushed by the frictional force applied by the external force and the high-speed rotational force of the membrane 114 during the polishing process, causing the problem that the supporter holes 120 are blocked. do.

As a result, the adsorption force of the wafer is weakened and the wafer is broken during transfer, or the pressure applied to the wafer is weakened, resulting in poor polishing of the wafer.

An object of the present invention is to provide a chemical mechanical polishing apparatus having a polishing head capable of stably fixing a wafer.

Another object of the present invention is to provide a chemical mechanical polishing apparatus having a polishing head capable of uniformly applying pressure to a wafer during a polishing process.

1 is a perspective view showing a general polishing head.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1 of a conventional polishing head loaded with a wafer. FIG.

3 is a cross-sectional view showing a post portion of a conventional polishing head.

4 shows a chemical mechanical polishing apparatus according to a preferred embodiment of the present invention;

5 and 6 show a polishing head according to a preferred embodiment of the present invention;

7 is a view showing the mounting state of the back film.

Explanation of symbols on the main parts of the drawings

200: polishing head

202: carrier

228: Retainer Ring

210: supporter

218: back film

224: membrane

According to a feature of the present invention for achieving the above object, in the apparatus for polishing a wafer, a polishing head includes a carrier, a reliner ring provided at a lower edge of the carrier, a supporter installed inside the carrier, A membrane covering so as to be spaced apart from the surface of said supporter; The supporter has posts protruding from the bottom surface and having vacuum holes for directly vacuum-adsorbing the wafer, and the posts of the supporter each have a back film surrounding the post for use as a medium for vacuum adsorption of the wafer. Attached.

According to the present invention, the supporter of the polishing head has posts protruding from the bottom surface and having vacuum holes formed therein, and having a cap-shaped back film covering the posts. Therefore, the back film is not pushed due to the rotational force of the polishing head and the pressure of the membrane during the polishing process, thereby preventing the problem of blocking the vacuum hole of the supporter.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the invention will be fully conveyed to those skilled in the art. Portions denoted by like reference numerals denote like elements throughout the specification.

4 is a view showing a chemical mechanical polishing apparatus according to a preferred embodiment of the present invention.

Referring to FIG. 4, the chemical mechanical polishing (CMP) apparatus 300 according to the present invention includes a polishing station 300 and a polishing head assembly 320 provided with a rotatable turntable 302 to which a polishing pad 306 is attached. Has

The turntable 302 is connected to a means (not shown) for rotating the turntable, and in the best polishing process, the rotating means rotates the turntable 302 at about 50 to 80 revolutions per minute. . Of course, lower or higher rotational speeds can be used. The polishing pad 306 may be a composite material having a rough polishing surface. The polishing station 300 includes conventional pad conditioning means 308 and reaction reagents (e.g., deionized water for polishing and oxidizing), friction particles (e.g., silicon dioxide for polishing and polishing) and chemical reaction catalysts (e. Slurry supply means 304 for supplying a slurry comprising potassium) to the surface of the polishing pad.

The polishing head assembly 320 includes a polishing head 200, a drive shaft 310 and a motor 312. The polishing head 200 holds the wafer against the polishing pad 306 and evenly distributes the downward pressure to the backside of the wafer. The polishing head 200 may be rotated at 40 to 70 revolutions per minute by the drive shaft 310 connected to the motor 312. Of course, lower or higher rotational speeds can be used. In addition, the polishing head 306 may be connected to at least one fluid supply channel used to apply pneumatic force and to vacuum the wafer to the bottom of the polishing head. Of course, pumps are respectively connected to these fluid supply channels.

5 and 6 are views showing a polishing head according to a preferred embodiment of the present invention, Figure 7 is a view showing the mounting state of the back film.

Referring to FIGS. 5 and 6, the polishing head 200 includes a carrier 202, a retainer ring 228, a supporter 210, a back film 218 and a membrane 224 of a flexible material. The supporter 210 is installed inside the carrier 202. The supporter 210 includes posts 214 in which a chamber 230 and a vacuum hole 212 are formed. The chamber 230 communicates with the gas inlet 232 of the carrier 202 and with the vacuum hole 212 formed in each of the posts 214 protruding from the bottom of the supporter 210.

The post 214 is attached with a back film 218 for use as a medium for fixing / unfixing the wafer. The back film 218 covers the post 214 and includes a film hole 220 at a position corresponding to the vacuum hole 212. The thickness of the back film 218 is preferably the same as that of the membrane 224, but may be smaller or larger than the thickness of the membrane 224.

The membrane 224 is a thin rubber film that is directly in surface contact with the wafer, and expands under pressure to apply uniform pressure to the wafer.

On the other hand, a retainer ring 228 is provided at the lower edge of the carrier 202. The retainer ring 228 prevents the vacuum-adsorbed wafer from escaping to the outside during the polishing process.

As described above, the present invention is attached to the cap-shaped back film to surround the post. Therefore, even when an external force is applied to the back film due to the rotational force and the distortion of the membrane during the polishing process, the back film can be prevented from being pushed to prevent the back film from blocking the vacuum hole.

In the above, the configuration and operation of the polishing head assembly according to the present invention is shown in accordance with the above description and drawings, but this is only an example, and various changes and modifications are possible without departing from the spirit of the present invention. Of course.

According to the present invention as described above, it is possible to provide a stable wafer fixing / non-fixing by smoothly entering and exiting the air through the vacuum hole.

In addition, according to the present invention, it is possible to provide a uniform pressure to the membrane even during a long polishing process can provide excellent polishing uniformity.

Claims (4)

1. An apparatus for polishing a wafer having a turn table with a polishing pad mounted on an upper surface thereof, and a polishing head for holding the wafer and forcing the wafer onto the turn table. The polishing head is A carrier, a retainer ring installed at a lower edge of the carrier, a supporter installed inside the carrier, and a membrane covering the cover so as to be spaced apart from the surface of the supporter; The supporter has posts protruding from the bottom surface and having vacuum holes formed therein for direct vacuum suction of the wafer, The post of the supporter is a chemical mechanical polishing apparatus, characterized in that each of the back film for use as a medium for vacuum adsorption of the wafer is attached to surround the post. The method of claim 1, The back film is a chemical mechanical polishing apparatus, characterized in that the cross section of the cap (cap) type. According to claim 1, And the membrane is fixed to the supporter to surround the bottom of the supporter. According to claim 1, And a retainer ring providing space at the bottom edge of the carrier for supporting the wafer.