KR20030045269A - Chemical mechanical polishing apparatus with a polishing head - Google Patents

Abstract

PURPOSE: A CMP(Chemical Mechanical Polishing) apparatus having a polishing head is provided to be capable of firmly fixing a wafer and uniformly pressing the wafer under a polishing process. CONSTITUTION: A CMP apparatus is provided with a turn table for loading a polishing pad and a polishing head(200) for fixing and pressing a wafer. The polishing head(200) further includes a carrier(202) having at least one gas path, a supporter(210) installed in the carrier(202), a back film(218) attached on the rear surface of the supporter(210), and a membrane(224) for contacting the wafer. The supporter(210) further includes a chamber and a plurality of supporter holes(212). At this time, the chamber is connected through the gas path and the supporter holes(212). Preferably, the back film(218) and the membrane(224) includes film holes(220) and membrane holes(226) corresponding to the supporter holes, respectively.

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 the line II ′ of FIG. 1 of a conventional polishing head loaded with a wafer. FIG. 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 is a view showing a chemical mechanical polishing apparatus according to a preferred embodiment of the present invention.

5 and 6 illustrate a polishing head according to a preferred embodiment of the present invention.

7 and 8 are views illustrating a polishing head in a state in which a wafer is fixed and a pressure is applied to the wafer, respectively.

The above technical problems can be provided by a chemical mechanical polishing apparatus having a polishing head having a back film attached to a supporter bottom. The apparatus has a turn table with a polishing pad mounted on an upper surface thereof, and a polishing head for holding a wafer and pressing the wafer onto the turn table. The polishing head includes a carrier having at least one gas entrance, a supporter installed inside the carrier, a back film attached to the front surface of the bottom of the supporter, and a membrane of flexible material in surface contact with the wafer. The supporter bottom is formed flat, and there is a supporter hole communicating with the gas entrance and exit on the supporter bottom. Film holes and membrane holes are formed at positions corresponding to the supporter holes of the back film and the membrane, respectively.

According to the present invention, the polishing head has a supporter having a flat bottom, and a back film covering the entire surface of the bottom of the supporter. 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 supporter hole.

The center of the supporter bottom surface of the polishing head according to the present invention may further include a center supporter hole communicating with the gas inlet and having a larger diameter than the supporter hole. In this case, a center film hole is formed in the back film at a position corresponding to the center supporter hole. The center supporter hole applies pressure to the membrane during the polishing process.

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 illustrate a polishing head according to a preferred embodiment of the present invention.

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 a chamber 230, a center supporter hole 214, and a plurality of supporter holes 212. The chamber 230 communicates with the gas inlet and outlet 232 of the carrier 202, and communicates with the plurality of supporter holes 212 formed in the bottom of the supporter 210. The bottom of the supporter 210 is made flat, and the edge portion of the bottom of the supporter is rounded. Alternatively, the edge portion of the bottom of the supporter may be chamfered. A back film 218 is attached to the bottom of the supporter for use as a medium when the wafer is fixed or unfixed. The back film 218 is attached to the front surface of the supporter and includes film holes 220 at positions corresponding to the supporter holes 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 20. Membrane holes 226 are formed in the membrane 224 at positions corresponding to the supporter holes 212 and the film holes 220 for vacuum adsorption of a wafer.

Meanwhile, a retainer ring 228 is installed at the lower edge of the carrier 202. This retainer ring 228 prevents the vacuum-adsorbed wafer from escaping to the outside during the polishing process.

In addition, a center supporter hole 214 having a larger diameter than the supporter holes 212 may be further provided at the center of the bottom surface of the supporter 210. In this case, a center film hole 222 is formed in the back film 218 at a position corresponding to the center supporter hole 214. However, no hole exists in the membrane 224 at a position corresponding to the center supporter hole 214 and the center film hole 222. The center supporter hole 214 is in communication with the chamber 230 and provides a strong pressure or strong adsorption force to the membrane 224 along with the supporter holes 212 when the wafer is fixed / unfixed.

7 and 8 are views illustrating a polishing head in a state in which a wafer is fixed and a pressure is applied to the wafer, respectively.

7 and 8, the chamber 230 of the supporter 210 to hold the wafer 20 by the polishing head 200 and move it to the polishing pad 306 on the turn table 302. ) And the air between the supporter 210 and the membrane 224 is sucked into or discharged from the gas inlet 232, and the inside of the chamber 230 is negatively pressured. Therefore, the wafer 20 is vacuum-adsorbed in contact with the membrane 224 through the supporter holes 212, the film holes 220, and the membrane holes 226.

The polishing head 200 is then lowered until the wafer 20 contacts the polishing pad 306. As shown in FIG. 8, the wafer 20 presses the upper portion of the polishing pad 306 by a predetermined pressing force.

Thereafter, air is introduced through the gas inlet 232 of the carrier 202, and the air is introduced through the supporter holes 212 and the film holes 220 to expand the membrane 224. The expanded membrane 224 exerts a uniform pressure on the entire top surface of the wafer 20. In this state, the slurry is supplied through the slurry supply means, and the polishing head 200 and the turn table 302 rotate in opposite directions to polish the lower surface of the wafer.

As described above, in the present invention, the back film is attached to the front surface of the supporter bottom surface. 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 adhesive force of the back film is strong to prevent the back film from blocking the supporter hole. In addition, since the membrane is in contact with the back film without directly contacting the supporter and the membrane, it is possible to prevent the membrane from being warped.

As described above, according to the present invention, it is possible to provide stable wafer fixing / unfixing by allowing air to enter and exit smoothly through the supporter hole, and effectively prevent the distortion of the membrane when the wafer is fixed.

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 (5)

In an apparatus for polishing a wafer: A turn table having a polishing pad mounted on an upper surface thereof; A polishing head for holding a wafer and forcing the wafer onto a turntable, The polishing head includes a carrier having at least one gas entrance, a supporter installed inside the carrier, a back film attached to the bottom of the supporter, and a membrane in surface contact with the wafer, wherein the supporter includes a chamber and its It has a plurality of supporter holes in the bottom surface, the chamber is in communication with the gas entrance and the supporter hole, the bottom of the supporter is flat, the back film and the membrane in the position corresponding to the supporter hole respectively film holes and A chemical mechanical polishing apparatus comprising membrane holes. According to claim 1, And the back film is attached to cover the front of the supporter. According to claim 1, And the membrane is fixed to the supporter to surround the bottom of the supporter. According to claim 1, A center supporter hole communicating with the chamber at the center of the bottom of the supporter; and And a center film hole at a position corresponding to the center supporter hole of the back film. According to claim 1, And a retainer ring providing space at the bottom edge of the carrier for supporting the wafer.