KR20130069418A - Membrane for chemical mechanical polishing having a hydrophobic layer - Google Patents

Abstract

PURPOSE: A membrane for a chemical and mechanical polishing device coated with a hydrophobic layer is provided to prevent a CMP membrane from being unable to detach from the rear side of a wafer after a CMP process by reducing the surficial friction of a hydrophobic layer coated on a CMP membrane body. CONSTITUTION: A membrane(100) for a chemical and mechanical polishing device coated with a hydrophobic layer comprises a membrane body(110b) and a hydrophobic coated layer(110a). The membrane body is composed of a silicon polymer compound. The hydrophobic coated layer is formed on the surface of the membrane body. The hydrophobic coated layer is composed of a silicon polymer compound in which a silica particle is dispersed.

Description

Membrane for Chemical Mechanical Polishing having a hydrophobic layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane for a chemical mechanical polishing apparatus, and more particularly, may be applied to a polishing head of a chemical mechanical polishing apparatus to apply the same or different pressure to multiple regions of a semiconductor substrate to improve uniformity of the chemical mechanical polishing process. And a membrane for a chemical mechanical polishing machine.

A semiconductor device is an electronic device formed by integrating a device having a fine size on a substrate, and a thin film deposition process, a photolithography process, an etching process, an ion implantation process, and the like are applied to manufacture such a semiconductor device. In order to form devices such as transistors and capacitors with high integration in semiconductor devices, semiconductor layers, metal layers, and insulating layers are formed by a complicated structure. For this purpose, the steps of the surface gradually increase as the thin film deposition and etching processes are repeatedly performed. Will be increased. If the step height of the surface is increased, the photoresist will be limited in forming a narrow line width in the subsequent photolithography process, so the planarization process should be added in the middle of the process.

Recently, chemical mechanical polishing (hereinafter referred to as 'CMP') has been widely used as a technology for planarizing a semiconductor surface. CMP is a process in which a surface containing a slurry containing abrasive particles and an etchant is rotated while contacting a surface of a pad with a surface of a substrate to simultaneously perform chemical mechanical polishing on an upper layer of the substrate. In such a CMP process, it is important to uniformly polish on a wafer-type substrate. If the polishing is not uniformly performed at the center and the outer portion of the wafer, the thickness of the interlayer insulating layer may be changed for each part of the wafer. This can cause open defects in the interior.

The membrane for CMP is a part that pressurizes the back side of the wafer so as to maintain a uniform pressure between the wafer and the CMP pad. The membrane for CMP is made of silicone rubber, and after being bonded to the polishing head, is divided into a plurality of regions so that gas can be injected from the outside. When the gas is injected from the outside at a constant pressure, each region of the membrane divided into a plurality of regions may swell, and may independently transmit pressure to different regions of the wafer. The structure and function of the membrane for CMP are disclosed in detail in Korean Patent Laid-Open Publication No. 2004-74269. The prior art relates to a CMP apparatus, comprising a platen, a polishing pad provided on the platen, and a polishing head for pressing the semiconductor substrate onto the polishing pad to polish the semiconductor substrate, wherein the polishing head includes the polishing head. A support plate having a plurality of holes formed on a bottom surface of the support plate, a pressing part positioned below the support plate and having a plurality of holes formed therein, a first fixing part extending upward from an edge of the pressing part, and an upper portion from the plurality of holes And a clamp having a second fixing part extended to the support plate, and a clamp positioned on the support plate to fix the membrane, thereby improving polishing uniformity of the wafer.

Membranes for CMP are generally made of a silicone polymer compound such as polysiloxane. Polysiloxanes are highly hydrophilic, and thus, the CMP membrane and the wafer backside often do not detach after the CMP process. In particular, this phenomenon occurs more frequently in the case of a dummy wafer or a wafer cleaned with hydrofluoric acid. As such, if the CMP membrane and the wafer are not separated, an alarm occurs in the equipment and the process progress is interrupted. Therefore, there is a great need for a technology that can improve the durability of the CMP membrane by improving the bonding force of the coating layer while controlling the surface frictional force of the membrane for CMP, while solving the above problems.

Therefore, the problem to be solved by the present invention is to improve the properties of the substrate contact portion in the membrane for CMP can be easily removable after the process and the membrane for CMP membrane, the bonding strength of the body and hydrophobic coating layer of the membrane for CMP is strong The coating layer is not easily separated and provides a membrane for CMP having excellent abrasion resistance.

In order to achieve the above object, the present invention is applied to a polishing head of a chemical mechanical polishing apparatus to apply the same or different pressure to a plurality of regions of a substrate, a membrane body made of a silicone polymer compound and a membrane in contact with the substrate It provides a membrane for a chemical mechanical polishing apparatus including a hydrophobic coating layer formed on the surface of the body.

According to an embodiment of the present invention, the hydrophobic coating layer may be made of a silicon polymer compound in which silica particles are dispersed.

According to another embodiment of the present invention, the silica particles may be spherical silica particles having a siloxane bond represented by Structural Formula 1 or Structural Formula 2 below.

Structure 1

(R is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination of these hydrocarbon groups)

Structural Formula 2

(R and R 'is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination thereof)

According to another embodiment of the present invention, the silica particles may be made of silsesquaoxane.

According to another embodiment of the present invention, the content of the silica particles is preferably 5 to 40% by weight of the hydrophobic coating layer.

The membrane for CMP of the present invention has the following effects.

1. The hydrophobic coating layer coated on the CMP membrane body reduces the frictional force of the surface, thereby preventing the CMP membrane from detaching from the back side of the wafer after the CMP process.

2. Since both the body of the membrane for CMP and the hydrophobic coating layer are made of a series of silicone polymer compounds, the mutual bonding force is high, and thus the coating layer can be prevented from peeling off due to stress received during CMP progress or handling.

3. Since the silica particles of the hydrophobic coating layer have excellent abrasion resistance, the durability of the membrane for CMP can be improved.

1 is a photograph of a membrane for CMP.
Figure 2 shows a membrane for CMP with a hydrophobic coating layer formed on the substrate contact portion in accordance with the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a membrane applied to a polishing head of a chemical mechanical polishing apparatus to apply the same or different pressure to a plurality of regions of a substrate, the membrane comprising a membrane body made of a silicone polymer compound and a hydrophobic coating layer formed on the surface of the membrane body. Characterized in that it comprises a.

The membrane for CMP is coupled to the CMP polishing head to perform a function of applying a certain pressure to the wafer in the direction of the CMP pad while being in contact with the backside of the semiconductor wafer. In order to perform such a function, the membrane for CMP must have elasticity so that the portion divided into a plurality of regions can be independently swelled by the gas injected from the outside, and there must be little aging due to long use. The membrane for CMP is made of a silicone polymer compound such as silicone rubber to satisfy this requirement. Unlike carbon-based polymers in which carbon atoms make up the main chain, silicone rubber forms a main chain by combining silicon atoms with oxygen atoms, and has a main chain crosslinked to have elasticity.

In the membrane for CMP of the present invention, a hydrophobic coating layer is formed on the surface of the substrate contact portion which is in contact with the back side of the substrate of the membrane body made of a silicone polymer compound. Figure 1 is a photograph of the membrane for CMP of the present invention, Figure 2 shows a membrane for CMP with a hydrophobic coating layer formed on the substrate contact portion. 1 and 2, the membrane 100 for CMP is made of a material having elasticity, and a plurality of pressure control parts formed by extending from the substrate contact part 110 and the substrate contact part 110 contacting the rear surface of the substrate. It consists of the parts (111 ~ 115). The membrane 100 for CMP may independently apply pressure to different areas of the substrate contact while gas is injected into the empty space between the different pressure regulators and the substrate contact. The membrane body 110b for CMP may be made of a silicone polymer resin, and may be molded by press molding or injection molding. Hydrophobic coating layer (110a) is formed on the surface of the substrate contact portion 100 in contact with the back of the substrate of the membrane body (110b) for CMP. The hydrophobic coating layer is a layer having a relatively hydrophobic physical property than the membrane body 110b for CMP, and serves to reduce the coefficient of friction of the surface of the substrate contact portion 100.

The membrane body for CMP may be manufactured by a liquid injection molding method of injecting A and B portions, which are reactants as raw materials, into a mold, and heat-crosslinking by heating to a predetermined temperature. In this case, part A may include silica, a base polymer, hexamethyldisilazane, and a platinum catalyst, and part B may include silica, a base polymer, hexamethyldisilazane, a polymerization inhibitor, and a crosslinking agent.

The hydrophobic coating layer may be formed of a silicon polymer compound in which silica particles are dispersed, and the silica particles may be spherical silica particles having a siloxane bond represented by the following Formula 1 or Formula 2. In formulas 1 and 2, R may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an unsaturated hydrocarbon group or a hydrocarbon group in combination thereof, and the aliphatic hydrocarbon group may be, for example, a methyl group, an ethyl group, a butyl group, and the aromatic carbon group may be, for example, a phenyl group. The unsaturated hydrocarbon group may be, for example, a vinyl group. The silica particles may have siloxane bonds in a network structure crosslinked in three dimensions, and may be specifically made of silsesquioxane.

The silica particles provide a hydrophobicity to the hydrophobic coating layer and control the degree thereof, and the degree of hydrophobicity varies depending on the content of the silica particles. The content of the silica particles is preferably 5 to 40% by weight of the hydrophobic coating layer. If the content of silica particles is less than 5% by weight, the hydrophobicity of the hydrophobic coating layer may not be sufficient, and thus the membrane may not be separated from the back side of the substrate after the CMP process. If the content of the silica particles exceeds 40% by weight, the hydrophobicity may be too high. It may be so strong that an error in sliding the membrane from the back side of the substrate may occur, or a peeling or cracking phenomenon may occur due to a weak bonding force between the membrane body and the hydrophobic coating layer.

Structure 1

(R is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination of these hydrocarbon groups)

Structural Formula 2

(R and R 'is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination thereof)

In the present invention, the method of forming a hydrophobic coating layer on the membrane body for CMP may be performed by various methods such as spraying, dipping, and brushing. A specific method of forming a hydrophobic coating layer is to mix a silicone oil (a low viscosity silicone rubber which is liquid at room temperature as a base polymer) and a first material containing silica and a second material including a catalyst and spray the mixed coating material. It is apply | coated by methods, such as dipping and brushing, and it hardens at high temperature. More detailed hydrophobic coating layer forming method will be described by using an embodiment.

According to the present invention, when the hydrophobic coating layer is formed on the substrate contact portion of the membrane for CMP, the following effects occur.

1. In the present invention, it is possible to solve the problem that the CMP membrane sticks to the back side of the substrate after the CMP process by adjusting the frictional force coefficient of the substrate contact portion of the membrane for CMP. In the semiconductor manufacturing process, the wafer, which is a substrate, has a different material on the front or back side of the substrate as the deposition process and the cleaning process are performed. At this time, the interaction force with the contact portion of the membrane substrate for CMP is different depending on the backside material of the substrate. For example, in the case of a bare wafer or a wafer cleaned with hydrofluoric acid, the interaction force is large, and thus the CMP Sticking of the membrane substrate contacts and the back side of the wafer may occur, preventing separation. However, when the hydrophobic coating layer is formed on the CMP membrane substrate contact portion as in the present invention, the coefficient of friction or the coefficient of adhesion between the substrate contact portion and the back side of the substrate can be appropriately adjusted. Can be solved.

2. In the present invention, since both the membrane body for CMP and the hydrophobic coating layer are made of a silicone polymer compound, the bonding force between the membrane body for CMP and the hydrophobic coating layer is improved. If the membrane body for CMP and the hydrophobic coating layer are made of polymer resins of different series, the bonding strength at the interface is relatively weak, and the hydrophobic coating layer is peeled off or cracked from the membrane body for CMP due to stress generated during the process or handling. May occur.

Hereinafter, the present invention will be described in more detail using examples. This embodiment is an embodiment presented to facilitate the present invention should not be limited to the scope of the present invention by the embodiment.

Example

Step 1 (forming the membrane body for CMP)

First, 69.5 g of VTP4M (polymer represented by Chemical Formula 1, purchased from Siyoung Tech), 24 g of Aerosil300 (purchased from Evonik), 6 g of hexamethyldisilazane (purchased from Evonik), Pt (0) -1,3-di Part A of the raw material mixed with 0.5 g of vinyl-1,1,3,3-tetramethyldisiloxane complex (platinum catalyst), VTP4M (a polymer represented by the following Chemical Formula 2, purchased from Siyoung Tech) 64.5 g, Aerosil300 24 g (purchased from Evonik), 6 g of hexamethyldisilazane, 0.5 g of 1-ethynyl-1-cyclohexanol (polymerization inhibitor), 5 g of YC483 (crosslinking agent represented by the following formula (5), purchased from Siyoung Tech) Part B of one raw material was prepared. Subsequently, the prepared raw material A part and the B part were mixed, and then the mixed raw material was supplied to the extruder, and fed into a mold connected to the extruder front end. At this time, the temperature of the extruder was 25 degreeC and the temperature of the metal mold | die was 120 degreeC. The raw material introduced into the mold was cured for 5 minutes and the molded membrane was ejected as the mold was separated. The membrane separated from the mold was then left in an oven at 200 ° C. for 240 minutes to remove residual volatiles.

Formula 1

(n is an integer from 1000 to 1300)

(2)

(m is an integer of 10 to 30, l is an integer of 10 to 30)

Step 2 (formation of hydrophobic coating layer)

A component of LSR TOP Coat (product name) manufactured by Momentive Performance Materials (solid content is about 73%, globular silica tospearl added to silicone oil by 20%) And B component (components containing a catalyst and the like as about 0.45% of solid content) were mixed at a mixing ratio of 1: 1. The mixed LS top coat was then applied by spraying to the substrate contact of the membrane body for CMP prepared according to Example 1-1, and cured in an oven at 180 ° C. for 30 minutes.

Comparative Example 1

Only one step of the example (molding of the membrane body for CMP) was performed to prepare a CMP membrane.

Comparative Example 2

The first step (molding of the membrane body for CMP) of Example was carried out, and parylene (type C) was heated and reacted in a vacuum to form a polymer of parylene C in polymer form.

The following experiment was performed on the membrane for CMP prepared according to the Examples and Comparative Examples.

Evaluation example 1 (sticking characteristic evaluation)

Experiments were carried out on the sticking of the silicon wafer with respect to the membrane for CMP prepared according to Examples and Comparative Examples. Specifically, the process was performed using CMP equipment of Applied Materials using dummy wafers, and after each cycle, the wafer was washed with water and loaded on the head again so that water was present on the wafer surface. The sticking was observed. Table 1 below shows the number of times sticking occurred during 21 process cycles.

Sample Sticking Count Example 0 Comparative Example 1 6 Comparative Example 2 One

Referring to Table 1, the sample of Example and Comparative Example 1 was evaluated as having no sticking or one-time sticking property, and Comparative Example 2, in which no coating layer was formed, had six sticking phenomenon. The sticking property was evaluated as bad.

Evaluation example 2 (durability evaluation)

The double sided tape was used to fix the bare silicon wafer on the bench with the back side up. The CMP membrane prepared according to Example and Comparative Example 2 was brought into contact with the back side of the bare silicon wafer, a metal weight (100 mm in diameter, cylindrical shape of 2 kg in weight) was placed on the CMP membrane, rotated 100 times, and formed on the CMP membrane. Cracking of the coating layer was observed. Cracks of the coating layer were not observed at all in the CMP membrane of the example, but a large number of cracks in the parylene C film were observed in the CMP membrane of Comparative Example 2.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Therefore, the embodiments described in the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: membrane for CMP 110: substrate contact portion
110a: hydrophobic coating layer 110b: membrane body
111-115: pressure regulator

Claims (5)

A membrane applied to a polishing head of a chemical mechanical polishing apparatus to apply the same or different pressure to multiple regions of a substrate,
A membrane body made of a silicone polymer compound; And
And a hydrophobic coating layer formed on the surface of the membrane body. The method according to claim 1,
The hydrophobic coating layer is a membrane for chemical mechanical polishing apparatus, characterized in that made of a silicon polymer compound in which silica particles are dispersed. The method according to claim 2,
The silica particle is a membrane for chemical mechanical polishing apparatus, characterized in that the spherical silica particles having a siloxane bond represented by the following formula (1) or (2).

Structural Formula 1

(R is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination of these hydrocarbon groups)

Structural Formula 2

(R and R 'is an aliphatic hydrocarbon group, aromatic hydrocarbon group, unsaturated hydrocarbon group or a combination thereof) The method according to claim 2,
Membrane for the mechanical mechanical polishing apparatus, characterized in that the silica particles made of silsesquaoxane. The method according to claim 2,
The content of the silica particles is a membrane for chemical mechanical polishing apparatus, characterized in that 5 to 40% by weight of the hydrophobic coating layer.

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