KR20150087931A - A method for manufacturing flexible membrane for head of chemical-mechanical polisher using brushing type of coating and flexible membrane manufactured by the same - Google Patents

Abstract

Provided are a method for manufacturing a flexible membrane for the head of a chemical-mechanical polisher using a brushing type of coating and a flexible membrane manufactured by the same. A method for manufacturing a flexible membrane for the head of a chemical-mechanical polisher according to the present invention includes a step of applying a polymer coating layer on a flexible membrane by a brushing type; and a step of thermally hardening the polymer coating layer. A flexible membrane according to the present invention can improve the yield of a chemical-mechanical polishing process with superior flatness compared to an existing flexible membrane. Moreover, the flexible membrane for the head of a chemical-mechanical polisher can effectively reduce yield loss and process time due to the non-detachment of a wafer by easily detaching the wafer after a process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible thin film for a chemical mechanical polishing head using a brushing type coating and a flexible thin film for a chemical mechanical polishing head manufactured by the method. membrane manufactured by the same}

The present invention relates to a method of manufacturing a flexible thin film for a chemical mechanical polishing head and a flexible thin film for a chemical mechanical polishing head produced by the method. More particularly, the present invention relates to a flexible thin film for a chemical mechanical polishing head, The present invention relates to a flexible thin film for a chemical mechanical polishing head capable of effectively reducing the processing time, yield loss, and the like due to wafer undispersibility since the yield of the polishing process can be improved and furthermore, will be

An integrated circuit is generally formed on a wafer, in particular a silicon wafer, by successive deposition of a conductor, semiconductor or insulating layer. After each layer is deposited, the layer is etched to generate circuit characteristics. As a series of layers are sequentially deposited and etched, the outer or top layer surface of the wafer, i.e., the exposed surface of the wafer, is gradually non-planarized. This non-planar outer surface is a problem for the integrated circuit manufacturer. If the wafer outer surface is not planar, then the photoresist layer lying thereon is also not planar. The photoresist layer is typically patterned by photolithographic devices that focus the light image on the photoresist. If the outer surface of the wafer is too rough, the maximum height difference between the peak and the valley of the outer surface will exceed the focus depth of the imaging device and the light image can not be properly focused on the outer surface of the wafer. Designing a new photolithographic device with improved focus depth is a fairly expensive operation. Also, as the minimum wiring width used in the integrated circuit becomes smaller, a shorter wavelength of light must be used, which further reduces the available focus depth. Thus, there is a need to periodically planarize the wafer surface to provide a substantial planar layer surface.

Chemical mechanical polishing (CMP) is one method of planarization, in which the chemical mechanical polishing is mounted on a polishing head to be planarized, the polishing head mounting of the wafer being mounted on the lower surface of the polishing head And the contact of the wafer with the flexible thin film. Thereafter, the wafer mounted on the head by contact with the flexible thin film comes into contact with the rotating polishing pad, the surface of which faces the contact surface with the flexible thin film. Wherein the head urges the wafer against the polishing pad and the head also rotates to provide additional movement between the wafer and the polishing pad. A polishing slurry comprising an abrasive and at least one chemical reagent is distributed on the polishing pad to provide a polishing chemical solution at the interface between the pad and the wafer. 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 wafer to form reaction sites. The polishing is performed by the interaction of the polishing pad having the reaction site and the abrasive particles.

Particularly in the CMP process, the polishing rate, the degree of finishing and the degree of flatness are determined by the pad and slurry combination, the relative speed between the wafer and the pad, and the force pressing the wafer against the pad. If the degree of flatness and finishing is insufficient, the wafer will be defective, so that the combination of the polishing pad and the slurry is selected according to the required degree of finishing and flatness. Under these conditions, the maximum throughput of the polishing apparatus is determined by the polishing rate. The polishing rate depends on the force with which the wafer is compressed against the pad. In particular, the greater the force, the faster the polishing rate. If the carrier head imposes a non-uniform load, i. E. The carrier head is subjected to a greater force only in one area of the wafer, the area of high pressure will be polished faster than the area of low pressure. Therefore, if the load is uneven, the wafer will be unevenly polished. One problem with recirculating CMP processes is that the edges of the wafer are often polished at a different speed than the wafer center (usually faster, sometimes slower). This problem, called the "edge effect ", occurs even when the load is uniformly applied to the wafer. The edge effect generally occurs at the periphery of the wafer, e.g., 5 to 10 mm of the outermost edge of the wafer. The edge effect reduces the overall flatness of the wafer, makes the periphery of the wafer unsuitable for use in an integrated circuit, and reduces the yield. Therefore, it is necessary to have a carrier head of a CMP apparatus that optimizes the polishing work throughput and provides a certain level of flatness and finish.

In general, the carrier head includes a main body, a flexible thin film (membrane) provided on the front surface of the main body to which the wafer is loaded, and a retainer ring mounted on the outer circumferential surface of the flexible thin film to prevent the wafer from being detached . Among them, the flexible thin film plays a role of directly contacting the wafer and pressing a certain force on the contacted wafer, and thus it is one of the most important parts. However, the flexible thin film according to the prior art has a problem that the semiconductor wafer is not detached from the head after the process, which is caused by the surface tension of the water film formed between the flexible thin film and the semiconductor wafer. That is, after the polishing process, the wafer must be easily unloaded (desorbed), the wafer is not easily detached due to moisture between the water and the thin film, causing process errors, and such a process error rate is very frequent in the field . Therefore, the edge effect can be effectively removed, and a flexible thin film can be easily removed from the flexible thin film even after the polishing process.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of manufacturing a flexible thin film for a chemical mechanical polishing head in which a wafer is easily detached and a polished wafer has an excellent edge profile.

Another object to be solved by the present invention is to provide a flexible thin film for a chemical mechanical polishing head in which a wafers can be easily detached and a polished wafer has an excellent edge profile.

According to an aspect of the present invention, there is provided a method of manufacturing a flexible thin film substrate, comprising: applying a polymer coating liquid on a flexible thin film substrate by a brushing method; And thermally curing the polymer coating layer.

In one embodiment of the present invention, the flexible thin film substrate is a silicon rubber, the polymer coating layer is a silicon polymer, and the silicone polymer is crosslinked by the thermal curing. Further, the polymer coating layer is curved in unevenness by the above-mentioned thermosetting. In one embodiment of the present invention, the polymer coating liquid was Silopren® LSR Topcoat TP 3719 (trade name) of GE Bayer Silicones. In addition, the thermosetting is performed at a temperature range of 100 to 200 캜.

The present invention further provides a flexible thin film for a chemical mechanical polishing head manufactured by the above-described method.

The present invention also relates to a flexible thin film substrate made of silicone rubber; And The present invention provides a flexible thin film for a chemical mechanical polishing head comprising a silicon rubber coating layer provided on the substrate and having a predetermined concavo-convex curvature portion, wherein the silicon rubber coating layer is formed by applying a silicone polymer liquid onto the substrate in a brushing manner , And then thermally cured.

The flexible thin film according to the present invention exhibits a superior edge profile as compared with the conventional flexible thin film to improve the yield of the chemical mechanical polishing process and further enables easy wafer detachment even after the process, To a flexible thin film for a chemical mechanical polishing head capable of effectively reducing processing time, yield loss, etc.

1 is a diagram illustrating a method of manufacturing a flexible thin film according to an embodiment of the present invention.
2 is a schematic view showing a manufacturing process of a flexible thin film according to an embodiment of the present invention.
3 is a photograph of the surface of the flexible thin film produced according to this embodiment.
4 and 5 are surface photographs of the flexible thin films of Comparative Examples 1 and 3, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to the drawings. However, the following contents are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

The present invention has noted that the coating characteristics of a flexible thin film for a conventional single-sided silicon rubber series chemical mechanical polishing head do not cover the driving mechanism of a complicated chemical mechanical polishing head merely by a hydrophobic characteristic. Particularly, a water film is formed between the flexible thin film and the semiconductor wafer, and the complicated chemical and mechanical mechanism in which the semiconductor wafer rotates in accordance with the rotation of the flexible thin film includes a hydrophobic material alone and a sufficient polishing effect It is difficult to achieve desorption. In addition, even in the case of the prior art in which an organic material such as parylene is coated on the surface of a thin film, a problem of sufficient polishing rate and wafer non-desorption can not be easily solved, and a chemical process of deposition of an organic material is required. .

In order to solve the above-described problems of the present invention, a method of spraying a liquefied polymer material, for example, a silicon polymer liquid onto a surface of a flexible thin film in a brushing form and then hardening the same, A flexible thin film for a mechanical polishing (CMP) head was prepared. That is, the inventor of the present invention coated and vapor-deposited a non-cured liquid silicone polymer on a silicon rubber, which is a silicone polymer used as a conventional flexible thin film, and cured and crosslinked the liquid silicone polymer in a vapor- Another silicone rubber coating layer is formed. The flexible thin film of the present invention manufactured in this manner has a densely curved structure (low surface roughness) on the surface and has a stable structure even in a head rotating at a high speed through homogeneous adhesion with the lower flexible thin film , While simultaneously solving the problem of low polishing rate and undesirable wafers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a process for manufacturing a flexible thin film for a chemical mechanical polishing head according to an embodiment of the present invention. FIG.

Referring to FIG. 1, a coating material, that is, a silicon polymer material is first applied to the surface of a flexible thin film substrate for a chemical mechanical polishing head made of silicon rubber in a brushing manner. The applied liquid silicone rubber is adsorbed on the flat thin film surface of the silicone rubber material. In one embodiment of the present invention, Silopren® LSR Topcoat TP 3719 (trade name, hereinafter, TP 3719) manufactured by GE Bayer Silicones, which is a silicone rubber which simultaneously applies two kinds of mixed polymer materials and a diluent on the surface and cross- As a silicon coating layer, the increase of frictional force and the improvement of wafer undispersed problem were simultaneously achieved. However, the scope of the present invention is not limited to this, and another material capable of forming a coating layer having irregular bends can be used, and this is within the scope of the present invention. TP 3719 used in one embodiment of the present invention is also bonded to the underlying silicon rubber in accordance with thermal curing, thereby allowing the coating material to fully engage the underlying flexible thin film substrate.

Thereafter, the liquid polymeric material is cured. The curing temperature is preferably 100 to 200 ° C, which corresponds to the curing temperature of TP 3719. In particular, in one embodiment of the present invention, the liquid silicone polymer is crosslinked to form another silicone rubber coating layer by the curing, and the silicone rubber coating layer exhibits excellent wafer desorption characteristics and polishing rate. If the curing temperature is lower than the above range, crosslinking is difficult to proceed at a sufficient rate, and if it exceeds the above range, the lower substrate is affected.

2 is a schematic view showing a manufacturing process of a flexible thin film according to an embodiment of the present invention.

Referring to Figure 2, a flexible thin film substrate 310 is first disclosed (A). The polymeric coating liquid 320 is applied to the flexible thin film substrate 310 (B). The brush 330 used to supply the polymer coating liquid 320 moves along the rail 340 to uniformly coat the polymeric coating liquid 320 on the flexible thin film substrate 310. The coating method may be various methods. However, the present invention particularly improves the economical efficiency by applying the coating method by the brushing method, and makes the irregular bending more densely.

Thereafter, the coated polymer coating liquid 320 is thermally treated and cured to form a coating layer 320 having a predetermined concavo-convex curved portion (C). In one embodiment of the present invention, the coating layer is a silicone rubber, and a silicone polymer solution such as TP 3719 is applied on the thin film substrate by a brush and then heat-treated. This solves the problem of wafer undispersed with increasing surface frictional force.

The concavo-convex curvature structure of the flexible thin film surface according to the present invention is very important in the chemical mechanical polishing process to which the present invention is applied.

As described above, the present invention forms a dense structure of the surface (this means that a smaller elevation bend is formed, which is also expressed as a lower surface roughness) by the silicon rubber which is cured after deposition. The dense structure (i.e., the concavo-convex structure of the low height car) reduces the unit contact area between the wafer and the flexible thin film, and the problem of wafer detachment due to the reduction of the contact area is solved. In addition to the compacted bending structure, the flexible thin film produced by the above-described method further increases the friction of the flexible thin film due to the dense concavo-convex bending, and by the increased frictional force, The flexible thin film achieves excellent polishing properties, edge polishing properties, and the like.

This will be described in more detail as follows.

In general, the chemical mechanical polishing head itself rotates at a high rpm, but the wafer to be actually polished is rotated by the flexible thin film which contacts and rotates. That is, the relative frictional force between the flexible thin film and the wafer that the water film is formed in between becomes the basic driving force for rotating the wafer. Therefore, if the frictional force of the flexible thin film is sufficiently secured, the number of revolutions of the flexible thin film and the wafer in contact with the flexible thin film becomes close to the number of revolutions of the head itself, thereby achieving a sufficient abrasive effect. That is, even if a water film due to water is formed between the wafer and the flexible thin film, the increased frictional force of the flexible thin film surface affects the actual wafer polishing.

Example  One

Example  1-1

Surface Coating

Silopren® LSR Topcoat TP 3719 from GE Bayer Silicones, a silicone polymer material, was applied to the flexible thin film (membrane) surface of the CMP equipment of the Appllite by brushing. Thereafter, the applied coating material was cured at 180 DEG C for 30 minutes. The coating material includes a silicone polymer liquid capable of crosslinking by heat, and a diluent thereof.

3 is a photograph of the surface of the flexible thin film produced according to this embodiment.

Referring to FIG. 3, it can be seen that the surface of the flexible thin film according to the present invention has a fairly dense surface curvature, thereby obtaining a low surface roughness.

Comparative Example  One

Sand was sprinkled on the surface of the mold, and a flexible thin film was formed on the basis of the mold, in which the curved portion of the sand was formed.

Comparative Example  2

In Comparative Example 2, an uncoated flexible film (Applied Materials, USA) was used.

Comparative Example  3

A flexible film coated with parylene (Applied Materials, USA) was used as Comparative Example 3.

Experimental Example  One

Frictional force measurement result

The coefficient of friction corresponding to the frictional force of the flexible thin film measured in the present invention is as follows. In this experiment, the frictional force was measured by dividing the water sprayed state and the water sprayed state.

Table 1 shows the frictional force in the state where no water is sprayed first.

Friction index Comparative Example 1 0.052 Comparative Example 2 0.076 Comparative Example 3 0.932 Example 1 0.937

Table 2 shows the frictional force of the water sprayed.

Sample Friction index Comparative Example 1 0.053 Comparative Example 2 0.154 Comparative Example 3 0.821 Example 1 0.961

With reference to the above results, it can be seen that the friction coefficient of the flexible thin film of the present invention (i.e., the flexible thin film of the present invention obtained by applying the silicone based polymer material by the brushing method and curing the same) ) Exhibits far higher frictional force than Comparative Example 3 having similar surface curvature.

Experimental Example  2

Wafer removal

In this experimental example, the CMP process was performed with CMP equipment of Applied Materials during 21 cycles with a dummy wafer. After each cycle, the wafer was cleaned with water and again loaded on the head to allow water to remain on the wafer surface.

Table 3 below shows the wafer desorption test results for the thin film of Sample # 1-4.

Sample No desorption number Comparative Example 1 8 Comparative Example 2 6 Comparative Example 3 One Example 1 0

Referring to the above results, it can be seen that the flexible thin film of the present invention, in which the surface roughness is generated by supplying silicone rubber to the surface in a brushing manner and then curing, can effectively remove the problem of wafer undispersed.

Experimental Example  3

Surface Photo

4 and 5 are surface photographs of the flexible thin films of Comparative Examples 1 and 3, respectively.

It can be seen that the surface of the flexible thin film according to the present invention and the flexible thin film of Comparative Example 3 have less dense surface curvature. Such a less dense surface curvature increases the unit contact area between the wafer and the thin film, thereby causing a problem that the wafer adheres to the thin film due to the surface tension when the wafer is unloaded. Comparative Example 1 has a very flat surface structure, whereby the wafer adheres to the thin film with a stronger force, as can be seen from the results of Experimental Example 2.

Claims (9)

A method of manufacturing a flexible thin film for a chemical mechanical polishing head,
Applying a polymer coating layer on a flexible thin film substrate by a brushing method; And
And thermally curing the polymer coating layer. The method according to claim 1,
Wherein the flexible thin film substrate is a silicon rubber. 3. The method of claim 2,
Wherein the polymer coating layer is a silicon polymer, and the silicone polymer is crosslinked by the thermal curing. The method of claim 3,
Wherein the polymer coating layer is formed with unevenness of curvature by the thermal curing. The method of claim 3,
Wherein the silicon polymer is Silopren 占 LSR Topcoat TP 3719 (trade name) manufactured by GE Bayer Silicones. The method of claim 3,
Wherein the thermosetting is performed at a temperature ranging from 100 to 200 < 0 > C. A flexible thin film for a chemical mechanical polishing head produced by the method according to any one of claims 1 to 6. A flexible thin film substrate made of silicone rubber; And
And a silicon rubber coating layer provided on the substrate and having a predetermined concavo-convex curvature portion. 9. The method of claim 8,
Wherein the silicone rubber coating layer is prepared by dispersing a silicone polymer liquid on the substrate in a brushing manner and then thermally curing the silicone rubber coating layer.

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