KR20100108820A

KR20100108820A - A flexible membrane for head of chemical-mechanical polisher

Info

Publication number: KR20100108820A
Application number: KR1020090027052A
Authority: KR
Inventors: 박기웅
Original assignee: 주식회사리온
Priority date: 2009-03-30
Filing date: 2009-03-30
Publication date: 2010-10-08

Abstract

A flexible thin film for a chemical mechanical polishing head is provided.

A flexible thin film for a chemical mechanical polishing head according to the present invention includes a circular main portion in contact with the substrate and providing pressure to the substrate; And a plurality of members extending from the main portion and constituting a plurality of pressing regions on the substrate, wherein a width ratio of the outermost pressing region and the pressing region adjacent to the outermost pressing region of the flexible thin film main portion is 0.05 to 0.1. The flexible thin film for chemical mechanical polishing head according to the present invention exhibits a better edge profile than the conventional flexible thin film, and as a result, the yield of the chemical mechanical polishing process can be improved. Furthermore, since the substrate can be easily detached after the process, it is possible to effectively improve the process time, yield loss, etc. due to the substrate non-desorption.

Description

A flexible membrane for head of chemical-mechanical polisher

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible thin film for chemical mechanical polishing heads, and more particularly, exhibits better edge profiles as compared to conventional flexible thin films, and as a result, the yield of the chemical mechanical polishing process can be improved, and furthermore, The present invention relates to a flexible thin film for a chemical mechanical polishing head capable of effectively improving a process time, yield loss, and the like due to substrate desorption, which can be easily removed after the process.

Integrated circuits are generally formed on substrates, particularly silicon wafers, by successive deposition of conductors, semiconductors or insulating layers. After each layer is deposited, the layers are etched to generate circuit characteristics. As a series of layers are successively deposited and etched, the outer or topmost surface of the substrate, i.e., the exposed surface of the substrate, gradually becomes nonplanarized. This non-planar outer surface presents a problem for integrated circuit manufacturers. If the substrate outer surface is not planar, the photoresist layer overlying it is not planar. The photoresist layer is generally po

It is patterned by photolithographic devices that focus the optical image on the toresist. If the outer surface of the substrate is too bumpy, the maximum height difference between peaks and valleys on the outer surface will exceed the depth of focus of the imaging device.

The optical image cannot be properly focused on the outer surface. Designing a new photolithography device with improved focus depth is a very expensive task. In addition, as the minimum wiring width used in integrated circuits becomes smaller, shorter wavelengths of light must be used, which further reduces the available depth of focus. It is therefore necessary to periodically planarize the substrate surface to provide a substantially planar layer surface.

Chemical mechanical polishing (CMP) is one method of planarization, wherein the chemical mechanical polishing is a wafer (substrate) to be flattened is mounted on a polishing head, and the polishing head mounting of the substrate is mounted on the lower surface of the polishing head. It is carried out by contact of the flexible thin film with the substrate. Subsequently, by contacting the flexible thin film, the substrate mounted on the head is brought into contact with the polishing pad whose surface opposite to the contact surface with the flexible thin film rotates. The head then presses the substrate against the polishing pad, and the head rotates to provide further movement between the substrate and the polishing pad. An abrasive slurry comprising an abrasive and at least one chemical reagent is distributed on the abrasive pad to provide an abrasive chemical solution at the interface between the pad and the substrate. This CMP process is quite complex and differs from simple wet sanding. In the CMP process, the reactants in the slurry react with the outer surface of the substrate to form reaction sites. Polishing is performed by the interaction of the abrasive particles with the polishing pad having the reaction site.

In particular, in a CMP process, the polishing rate, finish and flatness are determined by the pad and slurry combination, the relative speed between the substrate and the pad, and the force pushing the substrate against the pad. Insufficient flatness and finish results in defective substrates, so the combination of polishing pad and slurry is selected by the required finish and flatness. Under these conditions, the polishing rate determines the maximum throughput of the polishing apparatus. The polishing rate depends on the force with which the substrate is pressed against the pad. In particular, the greater this force, the faster the polishing rate. If the carrier head is subjected to non-uniform loads, ie if the carrier head is subjected to greater force in only one area of the substrate, the high pressure area will be polished more quickly than the low pressure area. Thus, if the load is uneven, the substrate will be unevenly polished. One problem with the ring CMP process is that the edges of the substrate are often polished at a different speed (generally faster, sometimes slower) than the substrate center. This problem, called the "edge effect", occurs even when the load is applied uniformly to the substrate. Edge effects generally occur at the periphery of the substrate, for example at the outermost 5 to 10 mm of the substrate. The edge effect reduces the overall flatness of the substrate, makes the periphery of the substrate unsuitable for use in integrated circuits, and reduces yield. Thus, there is a need for a CMP apparatus that optimizes the polishing throughput and provides the desired flatness and finish. In particular, the CMP apparatus should be equipped with a carrier head that provides substantially even polishing of the substrate.

Furthermore, the flexible thin film according to the prior art has a problem that the semiconductor substrate is not detached from the head after the process, due to the surface tension of the water film formed between the flexible thin film and the semiconductor substrate.

As described above, the conventional flexible thin film cannot effectively eliminate the edge effect, and also has a problem that the semiconductor substrate does not fall off from the flexible thin film even after the process due to the surface tension caused by the hydrophilic material present on the semiconductor substrate.

Accordingly, the problem to be solved by the present invention is to provide a new flexible thin film for chemical mechanical polishing head having a more easily removable substrate, an excellent edge profile and the like.

In order to solve the above problems, the present invention is a flexible thin film of a chemical mechanical polishing head including a flexible thin film for pressurizing a substrate, the thin film is in contact with the substrate, providing a pressure to the substrate Main part of; And a plurality of members extending from the main portion and constituting a plurality of pressing regions on the substrate, wherein a width ratio of the outermost pressing region and the pressing region adjacent to the outermost pressing region of the flexible thin film main portion is 0.05 to 0.1. Provided is a flexible thin film for chemical mechanical polishing heads.

The innermost member of the member is inclined at a predetermined angle toward the center of the flexible thin film, and the remaining members except for the innermost member extend perpendicular to the main portion.

In addition, the flexible thin film for a chemical mechanical polishing head according to an embodiment of the present invention has a structure in which a coupling portion between the outermost member and the main portion of the member is recessed.

In another embodiment of the present invention, the flexible thin film is a structure coated with a hydrophobic material than the flexible thin film on the mounting surface with the substrate, in one embodiment of the present invention the hydrophobic material is perylene to be.

The flexible thin film for chemical mechanical polishing head according to the present invention exhibits a better edge profile as compared to the conventional flexible thin film, and as a result, the yield of the chemical mechanical polishing process can be improved. Furthermore, since the substrate can be easily detached after the process, it is possible to effectively improve the process time, yield loss, etc. due to the substrate non-desorption.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the following contents are all for illustrating the present invention, and the scope of the present invention is not limited thereto or limited.

1 is a cross-sectional view showing a flexible thin film for a chemical mechanical polishing head according to an embodiment of the present invention.

Referring to FIG. 1, the flexible thin film for a chemical mechanical polishing head according to the present invention includes a circular main part 110 in which a substrate (wafer 100) contacts one side, and a plurality of members 120a extending from the main part. b, c, d).

The member may have a circular shape having the same shape as the main portion of the circular shape, and the spaces 130a, b, c, and d between the members become spaces separated from each other after the head assembly. That is, when air is injected into one of the spaces 130a after the head assembly, only the substrate region under the one space 130a is pressed. In this manner, the flexible thin film according to the present invention includes members spaced at predetermined intervals in order to press independent substrates.

In addition, the space separated by the member may be not only a pressurized space but also a vacuum space. That is, under vacuum conditions, the flexible thin film is deformed toward the head rather than the substrate side, wherein a vacuum is maintained between the substrate and the flexible thin film, and as a result, the substrate is held in the flexible thin film.

3 is a cross-sectional view showing an outer pressurized region of the flexible thin film according to the present invention.

The flexible thin film according to the present invention is characterized in that, unlike the conventional flexible thin film, the width ratio of the outermost pressing area 130d of the main part and the pressing area 130c adjacent to the outermost area is 0.05 to 0.1. It provides a flexible thin film for a chemical mechanical polishing head.

That is, the ratio (a / b) of the outermost pressing area width a and the adjacent pressing area width b of the flexible thin film according to the prior art was about 1/5, but in this case, it is not easy to adjust the profile of the substrate edge. The inventors have found that it is not repeated through repeated experiments, and found that an excellent edge profile can be obtained when the ratio is set to 0.1 or less. However, edge profile adjustment is virtually impossible when the ratio is less than 0.05. Therefore, the present inventor proposes a width ratio of two outer pressurized regions to 0.05 to 0.1, and the effect according to the width ratio will be described in more detail in the following experimental example.

In addition, the flexible member according to another embodiment of the present invention discloses a flexible thin film having a structure in which the innermost member 120a of the thin film is inclined at a predetermined angle toward the center of the thin film.

4 is a cross-sectional view of the flexible member according to the embodiment of the present invention.

Referring to FIG. 4, the innermost member 120a of the flexible member is inclined toward the center of the thin film by a predetermined angle. In this case, the center pressurization region of the pressurization region of the substrate may be wider. The inventors noted that a vacuum for mainly maintaining the substrate in the head is supplied to the center region. Sufficiently secured. In addition, the substrate edge control may be facilitated through the structure of the innermost member 120a, which will be described in more detail below.

In addition, by making the connection portion between the outermost member and the main portion of the flexible member according to one embodiment of the structure recessed by a predetermined depth, a further improved edge profile can be obtained.

5 is a cross-sectional view showing an outermost member of the flexible member according to an embodiment of the present invention.

Referring to FIG. 5, it can be seen that the flexible member according to the present invention recesses the outermost member 120d and the connecting portion 'a' of the main part by a predetermined depth, thereby making a thinner connection. That is, the present inventors improved the responsiveness to pressure by allowing the outermost member to be more easily deformed when pressure is applied. Furthermore, in the case of the other members except for the outermost member 120d, since the uniform polishing profile cannot be obtained, the present invention particularly improves only the pressure-responsiveness to the outermost member. It starts.

The present invention further proposes a flexible member having a structure in which a thin film having a higher hydrophobicity than the flexible thin film is laminated on one side of the flexible thin film on which the semiconductor substrate to be polished is mounted.

That is, the present inventors have recognized that the non-desorption problem of the semiconductor substrate is caused by the water film formed between the substrate and the flexible thin film. We have found that the problem can be significantly improved.

Hereinafter, the experimental results of the flexible thin film of the present invention will be described.

Experimental Example One

edge Profile experiment

In the present experimental example, the edge profile of the flexible thin film (Example 1) of the present invention having a width ratio of the outermost pressurized region and the outermost pressurized region (0.05) and the flexible thin film having a width ratio of 0.2 (Comparative Example 1) was obtained. Measured. In addition, the flexible thin film of Example 1 has a structure in which a coupling portion between the outermost member and the main portion is recessed (see FIG. 5).

The CMP device in this example was Reflexion LK from Applied Materials.

6 is a graph showing the polishing results according to the present experimental example.

Referring to FIG. 6, it can be seen that in the prior art flexible thin film having a width ratio of 0.2, a so-called edge fastening phenomenon occurs in which edge portions are polished considerably, and the edge profile is affected. The present inventors recognized that such edge fast phenomenon was eventually caused by an excessively wide outermost region, and narrowed it to 0.05 level, thereby improving the edge fast phenomenon. From the above results, it can be seen that when the width ratio is set at 0.05 level and the ratio of the outer region is narrowed, the edge profile becomes very good. Furthermore, the connection between the outermost member and the main part is recessed so that the pressure change is reduced. It can be seen that when the outermost member has a structure that can deform more quickly, the edge profile becomes better.

Experimental Example 2

Solve Wafer Desorption by Coating

In this Experimental Example, a flexible thin film made of uncoated silicon rubber material (Comparative Example 2) was compared with a flexible thin film coated with a hydrophobic material (perylene c) higher than the silicon rubber on the silicon rubber (Experimental Example 2). Experiment.

In this experiment, in the case of Comparative Example 2, the semiconductor substrate was bonded to the carrier head after the process from the first time, and thus a problem of not being detached occurred. However, in the case of the flexible thin film according to the present invention, no semiconductor substrate non-desorption problem occurred until the first 30 process cycles.

Figure 2 is a front view showing a flexible thin film for a chemical mechanical polishing head according to an embodiment of the present invention.

Claims

A flexible thin film of a chemical mechanical polishing head comprising a flexible thin film for pressurizing a substrate,

The thin film includes a circular main portion in contact with the substrate and providing pressure to the substrate; And

A plurality of members extending from the main part and constituting a plurality of pressing areas on the substrate, wherein a width ratio of the outermost pressing area and the pressing area adjacent to the outermost pressing area of the flexible thin film main part is 0.05 to 0.1; A flexible thin film for chemical mechanical polishing heads, characterized in that.

The method of claim 1,

The innermost member of the member is a flexible thin film for a chemical mechanical polishing head, characterized in that inclined at a predetermined angle toward the center of the flexible thin film.

3. The method of claim 2,

A flexible thin film for a chemical mechanical polishing head, wherein the remaining members except the innermost member extend perpendicularly to the main portion.

The method of claim 1,

And a coupling portion between the outermost member and the main portion of the member is recessed.

The method of claim 1,

The flexible thin film is a flexible thin film for a chemical mechanical polishing head, characterized in that the hydrophobic material is coated on the mounting surface with the substrate than the flexible thin film.

The method of claim 1,

And said hydrophobic material is perylene.