KR20030012646A - Polishing head of a chemical mechanical polishing machine - Google Patents

Abstract

PURPOSE: A polishing head of a chemical mechanical planarization machine is provided to prevent deformation of a retainer ring and reduce time for exchanging the retainer ring by simplifying a coupling or decoupling structure of the retainer ring. CONSTITUTION: A polishing head(130) includes a manifold(132), a carrier(134), a retainer ring(140), a plate, and a membrane(170). The carrier(134) is located at a lower portion of the manifold(132). The plate is installed in the inside of the retainer ring(140). The plate is connected with the manifold(132) through the carrier(134). The membrane(170) is formed with a thin rubber layer contacted with a back face of a wafer. The membrane(170) is expanded according to a pressure. The retainer ring(140) is installed at an edge of a lower end portion of the carrier(134) in order to prevent separation the wafer from the polishing head(130). The retainer ring(140) is formed with an upper ring(140a) and a lower ring(140b).

Description

Polishing head of chemical mechanical flattening machine {POLISHING HEAD OF A CHEMICAL MECHANICAL POLISHING MACHINE}

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 polishing surface (process surface) of the wafer which simultaneously chemically polishes the wafer is widely used.

Typically, in a CMP process, a wafer is mounted on a polishing head such that its polishing surface (process surface) faces the turntable, and the polishing surface (process surface) of the wafer is placed on a turntable provided with a polishing pad. The polishing head provides a controllable pressing force (rod) on the wafer to press the backside of the wafer against the polishing pad of the turntable. The polishing head may also rotate to provide additional motion between the wafer and the turntable. .

An effective CMP process is to process wafers of uniform flatness at high polishing rates. Characteristics such as the uniformity, flatness, and polishing speed of the wafer polishing surface are greatly influenced by the relative speed between the wafer and the polishing pad, and the pressing force of the wafer against the polishing pad. In particular, the higher the polishing rate is, the higher the pressing force against the polishing pad is, the faster the polishing rate is. Thus, when a non-uniform pressing force is applied from the polishing head to the wafer, certain areas of the wafer that are subjected to relatively high pressure will be polished faster than other areas that are subjected to relatively small pressure.

Polishing uniformity in the CMP process is characterized in terms of equipment, ie head structure. Therefore, CMP companies have been actively developing and applying heads of a member type having excellent polishing uniformity. Among them, the deformation of the retainer ring has a great influence on the wafer profile after CMP.

In particular, this retainer ring is a situation that is frequently replaced because of the short life time. However, as shown in Figs. 1 and 2, the retainer ring 12 in the conventional CMP head 10 has a structure that is coupled by a plurality of bolts 14, the bolt 14 in the assembly process Deformation of the retainer ring 12 is caused by the tightening force of.

As can be seen in Figure 2, in the conventional polishing head 10, the retainer ring 12 should be in close contact with the pad evenly, whereas the bolt fastening point portion is substantially lifted due to the tightening force of the bolt 14 This will occur. This deformed deformation causes deformation of the profile of the pad in the process of applying the prosher to the retainer ring, which causes hunting in the wafer profile after CMP.

In addition to this problem, the conventional retainer ring 12 must be reassembled after the polishing head is completely detached from the cross to replace it after its lifetime. This takes too much time, there is a problem that takes a lot of time to back up the equipment due to the large number of checks related to the change point because of the separate coupling of the head after replacement.

It is an object of the present invention to provide a novel type of wafer polishing apparatus capable of preventing deformation of the retainer ring.

Another object of the present invention is to provide a novel type of wafer polishing apparatus for the manual desorption of retainer rings.

1 is an exploded perspective view of a conventional polishing head;

2 is a cross-sectional view for explaining the fastening relationship of the retainer ring in the conventional polishing head;

3 is an exploded perspective view of a CMP apparatus according to a preferred embodiment of the present invention;

4 is an exploded perspective view of a polishing head according to a preferred embodiment of the present invention;

5 and 6 are cross-sectional views of the polishing head.

* Explanation of symbols for the main parts of the drawings

110: polishing station

112: Polishing Pads

114: turntable

118: slurry supply means

120: polishing head assembly

122: drive shaft

130: polishing head

132: manifold

134: carrier

140: retainer ring

140a: upper ring

140b: lower ring

170: membrane

According to a feature of the present invention for achieving the above object, an apparatus for polishing a wafer includes a support portion having a polishing pad mounted on an upper surface thereof; A polishing head positioned on a polishing pad of said support for holding a wafer; The polishing head includes: a manifold for distributing air supplied from the outside into the polishing head; A carrier disposed below the manifold; A recess is formed to receive the semiconductor wafer, and has a retaining ring disposed under the carrier and coupled thereto.

In the present invention as described above is disposed in the retaining ring, connected to the manifold through the carrier, the plate for providing a pressure acting on the semiconductor wafer by the air supplied from the manifold; It may further include a membrane (membrane) which is a thin rubber film installed to surround the wafer holding surface of the plate.

In the present invention as described above is provided between the manifold and the carrier, it may further include a first elastic body for elastically moving the carrier relative to the manifold by the air supplied from the manifold.

In the present invention, the second elastic body for one end is coupled to the retaining ring, the other end is coupled to the plate, and the plate elastically moves with respect to the retainer ring by air supplied from the manifold. It may further include.

The retainer ring in the present invention as described above is fixed by a plurality of bolts in the lower portion of the carrier and the upper ring threaded portion; It may be made of a lower ring that is screwed to the upper ring having a screw portion corresponding to the threaded portion of the upper ring.

In the present invention, the upper ring is made of a metal that can be used permanently without deformation, and the lower ring may be made of thermoplastic polyphenylene sulfide (PPS; POLYPHENYLENE SULFIDE).

In the present invention as described above, the upper ring and the lower ring in contact with the o-ring or gasket may be mounted to prevent friction and to prevent contamination.

In the present invention as described above, the screw coupling direction of the upper ring and the lower ring may be opposite to the rotation direction of the polishing head.

For example, the embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. These embodiments are provided to more completely describe the present invention to those skilled in the art. Accordingly, the shape of the elements in the drawings and the like are exaggerated to emphasize a clearer description.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 3 to 6. In the drawings, the same reference numerals are used for components that perform the same function.

Referring to FIG. 3, the CMP apparatus 100 according to the present invention has a polishing station 110 and a polishing head assembly 120 provided with a rotatable turntable 114 to which a polishing pad 112 is attached.

The turn table 114 is connected to means (not shown) for rotating the turn table, and in the best polishing process, the rotating means rotates the turn table 114 at about 50 to 80 revolutions per minute. Let's do it. Of course, lower or higher rotational speeds can be used. The polishing pad 112 may be a composite material having a rough polishing surface. The polishing station 110 includes conventional pad conditioning means 116 and reaction reagents (e.g., deionized water for oxidative polishing), friction particles (e.g., silicon dioxide for oxidative polishing), and chemical reaction catalysts (e.g., hydroxide for oxidizing polishing). Slurry supply means 118 for supplying a slurry comprising potassium) to the surface of the polishing pad. Here, the pad conditioning means and the slurry supply means do not correspond to the gist of the present invention and are well known techniques, and thus detailed description thereof is omitted here.

The polishing head assembly 120 includes a polishing head 130, a drive shaft 122, and a motor 124. The polishing head 130 holds the wafer 10 against the polishing pad 112 and evenly distributes the downward pressure to the backside of the wafer. The polishing head 130 may rotate at 40 to 70 revolutions per minute by the drive shaft 122 connected to the motor 124. Of course, lower or higher rotational speeds can be used. In addition, at least two fluid supply channels may be connected to the polishing head 130 to provide an air pressure or a vacuum for adsorbing the wafer into a vacuum. Of course, pumps are respectively connected to these fluid supply channels.

Next, the polishing head 130 will be described in detail with reference to FIGS. 4 to 6. The polishing head 130 includes a manifold 132, a bowl-shaped carrier 134, a retainer ring 140, a plate 142, and a membrane 170 of a flexible material.

The manifold 132 is a part for dispersing three fluid supply channels supplied from the outside into the carrier, and a carrier 134 corresponding to the body of the head is positioned under the manifold 132.

The plate 142 is accommodated in the retainer ring 140. The plate 142 is connected to the manifold 132 through the carrier 134 and provides a pressure acting on the semiconductor wafer by air supplied from the manifold 132. Of course, the pressure is provided to the semiconductor wafer by a membrane 170, which is a thin rubber film surrounding the plate 142. The membrane 170 is a thin rubber film that is directly in surface contact with the back surface 10a of the wafer, and expands under pressure to apply a load to the back surface 10a of the wafer 10.

Meanwhile, a retainer ring 140 is installed at the lower edge of the carrier 134. The retainer ring is a part for preventing the wafer w from being separated from the polishing head 130 during the polishing process. The retainer ring 170 has a top ring 170a that does not need to be removed after it is fixed. , The lower ring 170b is replaced according to the life time. The upper ring 170a is fixed to the lower portion of the carrier by a plurality of bolts 190, and the lower ring 170b is fixedly coupled to the upper ring 170a by screwing to facilitate detachment. To this end, the thread (s) is formed on the inner surface of the upper ring (170a), the thread (s) is formed on the surface corresponding to the thread (s) of the upper ring in the lower ring (170b). As such, the lower ring 170b is screwed to the upper ring 170a. Here, the screw is preferably manufactured so that the head can be tightened clockwise because the head rotates in the counterclockwise direction. O-rings (not shown) or gaskets (not shown) may be mounted at portions where the upper ring 170a and the lower ring 170b contact each other to prevent friction and infiltrate contaminants.

On the other hand, the upper ring (170a) is made of a metal material that is less deformation, can be used permanently, the lower ring is preferably made of polyphenylene sulfide (PPS; POLYPHENYLENE SULFIDE) is a thermoplastic enpra (engineered plastic) Do.

Meanwhile, the polishing head 130 includes a first elastic body 136 between the manifold 132 and the carrier 134. The first elastic body 136 is expanded by elasticity when it is pressurized. The first elastic body 136 buffers through expansion and contraction between the manifold 170 and the carrier 134. An inner tube 138 is located at the center (not shown) and the edge of the plate 142. The inner tube 138 expands when pressure is applied to prevent the wafer w from biasing during polishing. The second elastic body 144 enables expansion and contraction between the retainer ring 170 and the plate 142. The first elastic body 138 and the second elastic body 144 are rubber materials to enable expansion and contraction.

As such, the structural feature of the present invention is that the retainer ring is divided into an upper ring which is always coupled to the carrier, and a lower ring which is replaced when the life time is over. The lower ring is screwed to the upper ring. As such, the retainer ring of the present invention can prevent the deformation caused by the tightening force difference in the bolt fastening portion that has been a problem in the existing retainer ring. In addition, there is an advantage in that the replacement of the lower ring can be easily replaced in the mounted state without removing the head from the cross.

Although the present invention has been illustrated and described through the preferred embodiments, it should be noted that the present invention is not limited thereto, and various embodiments and modifications may be made without departing from the spirit and technical scope of the present invention. It is important to understand that there may be.

According to the present invention as described above, the deformation of the retainer ring can be prevented, and since the retainer ring can be detached by hand, the replacement time of the retainer ring can be shortened.

Claims (10)

In an apparatus for polishing a wafer: A support having a polishing pad mounted on an upper surface thereof; A polishing head positioned on a polishing pad of said support for holding a wafer; The polishing head is A manifold for distributing air supplied from the outside into the polishing head; A carrier disposed below the manifold; And a retaining ring formed in the recess for accommodating the semiconductor wafer and disposed below and coupled to the carrier. The method of claim 1, A plate disposed inside said retainer ring, connected to said manifold through said carrier, for providing pressure acting on said semiconductor wafer by air supplied from said manifold; Wafer polishing apparatus, characterized in that it further comprises a membrane (membrane) which is installed to surround the wafer holding surface of the plate. The method of claim 1, And a first elastic body disposed between the manifold and the carrier and configured to elastically move the carrier with respect to the manifold by air supplied from the manifold. The method of claim 1, One end is coupled to the retainer ring, the other end is coupled to the plate, further comprising a second elastic body for causing the plate to elastically move with respect to the retainer ring by air supplied from the manifold Wafer polishing apparatus. The method of claim 1, The retaining ring is An upper ring fixed by a plurality of bolts at the bottom of the carrier and having a threaded portion at the bottom thereof; Wafer polishing apparatus, characterized in that consisting of a lower ring having a screw portion corresponding to the threaded portion of the upper ring screwed to the upper ring. The method of claim 5, The upper ring is a wafer polishing apparatus, characterized in that the deformation is made of a metal that can be used permanently. The method of claim 5, Wafer polishing apparatus, characterized in that the lower ring is made of a thermoplastic enpra. The method of claim 7, wherein Wafer polishing apparatus, characterized in that the thermoplastic enpra is polyphenylene sulfide (PPS; POLYPHENYLENE SULFIDE). The method of claim 5, A portion of the upper ring and the lower ring in contact with the wafer polishing apparatus, characterized in that the O-ring or gasket is mounted to prevent friction and to prevent contamination. The method of claim 5, The screwing direction of the upper ring and the lower ring is a wafer polishing apparatus, characterized in that the opposite direction to the rotation direction of the polishing head.