TWI861628B - Composite sheet having excellent thermal and electric conductivities for plasma process equipment - Google Patents

Abstract

The present invention relates to a thermal and electrically conductive composite sheet in which thermal resistance is reduced by controlling the hardness of a carbon-based coating layer, and more particularly, by controlling the hardness of a conductive layer containing a carbon-based compound and a polymer binder to reduce thermal resistance.

Description

Composite sheet with excellent thermal and electrical conductivity suitable for plasma process equipment

The present invention relates to a composite sheet with excellent thermal conductivity and electrical conductivity, which reduces thermal resistance by controlling the hardness of a carbon-based coating, and more specifically, to a composite sheet with excellent thermal conductivity and electrical conductivity, which reduces thermal resistance by controlling the hardness of a conductive layer including a carbon-based compound and a polymer binder.

Semiconductor manufacturing process equipment that uses plasma such as vacuum deposition and dry etching will generate serious thermal and various electromagnetic problems due to high plasma density and driving power during process operation. These thermal and electromagnetic problems have a great impact on the process yield of silicon wafers, especially solving the thermal problem of the upper and lower electrodes where high voltage is applied has become a big problem.

On the other hand, as a means to solve the thermal problems and plasma-related electromagnetic instability of the electrode part of the semiconductor process equipment, a method to quickly transfer heat and solve the problem of local heat concentration is used by installing materials with high thermal and electrical conductivity on the electrode part of the process equipment. In particular, the thermal conductivity and electrical conductivity of the heat dissipation material used inside the electrode part greatly affect the process yield, so research is conducted on raw materials for developing heat-generating materials with excellent thermal and electrical conductivity.

In the past, as heat sinks for semiconductor process equipment, composite materials with conductive carbon raw materials coated on both sides of metal foils such as Al and Cu were often used. However, when continuously exposed to an extreme plasma environment, the metal foil and the conductive carbon raw materials separated (delamination). This factor affects the process yield as the semiconductor process time passes, and attempts have been made to find a solution to this problem.

Therefore, from the perspective of heat dissipation and hardness, research and development of composite sheets that can be applied to plasma process equipment is currently needed.

Existing technical literature

Patent Literature

Reference 1: Korean Patent No. 10-1939170

Reference 2: Korean Patent No. 10-2053326

The purpose of the present invention is to provide a composite sheet having excellent thermal conductivity and electrical conductivity by reducing thermal resistance by controlling the hardness of a carbon-based coating to satisfy sufficient hardness and low thermal resistance.

As an embodiment of the present invention, a composite sheet with excellent thermal conductivity and electrical conductivity includes: a substrate; a primer layer formed on at least one side of the substrate; and a conductive layer formed on the upper part of the primer layer, including a carbon-based compound and a polymer binder, and a Shore A hardness ranging from 50 to 95 Shore A.

The feature of the present invention is that the polymer adhesive includes a main agent, a curing agent and a filler.

The feature of the present invention is that the weight ratio of the main agent and the curing agent is 1:0.6 to 1.2.

The present invention is characterized in that the main agent is a compound including vinyl groups, the curing agent is a compound including hydrogen groups, and the vinyl groups of the main agent and the hydrogen groups of the curing agent react to produce crosslinking.

The present invention is characterized in that the weight ratio of the carbon-based compound to the polymer binder is 1:0.2 to 30.

The present invention is characterized in that the maximum diameter of the above-mentioned carbon-based compound is 0.01 to 100 μm.

The present invention is characterized in that the above-mentioned carbon-based compound includes one or more selected from the group consisting of graphite, carbon nanotubes (CNT), graphene, graphene oxide, carbon fiber, fullerene, carbon, nanocarbon, and carbon black.

The present invention is characterized in that the polymer adhesive is one or more selected from the group consisting of thermosetting silicone rubber compounds, one-component thermosetting silicone adhesives, two-component thermosetting silicone adhesives, acrylic resins, epoxy resins, urethane resins and urea resins.

The present invention is characterized in that the thickness of the conductive layer is 5 to 450 μm.

The present invention is characterized in that the average density of the conductive layer is 1.0 to 5.0 g/cc.

The present invention is characterized in that the porosity of the conductive layer is less than 5%.

The feature of the present invention is that the thermal resistance of the composite sheet is in the range of 0.8 to 1.3K/W.

The present invention is characterized in that the ratio of (Shore A hardness)/(thermal resistance) of the composite sheet is in the range of 50 to 90 (Shore A)/(K/W).

According to the thermally conductive and electrically conductive composite sheet of the present invention, the ratio of the main agent and the curing agent can be changed, and the thermal resistance can be reduced by controlling the hardness of the carbon-based coating to reduce the process yield.

The present invention may be modified in many ways and may have many embodiments. The terms used in this application are only used to illustrate specific embodiments and are not intended to limit the present invention. Unless defined in another way, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by ordinary technicians in the technical field to which the present invention belongs. Commonly used terms as defined in the dictionary should be interpreted as having a meaning consistent with the meaning in the context of the relevant technology, and unless clearly defined in this application, they are not interpreted as ideal or overly formal meanings.

As an embodiment of the present invention, a composite sheet with excellent thermal conductivity and electrical conductivity includes: a substrate; a primer layer formed on at least one side of the substrate; and a conductive layer formed on the primer layer, including a carbon-based compound and a polymer binder.

The Shore A hardness of the composite sheet of the present invention is preferably 50 to 95 Shore A, more preferably 75 to 95 Shore A, and most preferably 80 to 95 Shore A. In addition, the thermal resistance of the composite sheet is preferably 0.8 to 1.3K/W, more preferably 1.0 to 1.2K/W. In addition, the wear resistance of the composite sheet is preferably 2 to 3%, preferably 2 to 2.7%. When it is less than the above range, the thermal resistance of the contact interface becomes lower, but the workability such as surface stickiness and scratches during operation becomes worse. When it is greater than the above range, as the thermal resistance of the contact interface becomes higher, the thermal resistance increases, so it is not preferred.

The (Shore A hardness)/(thermal resistance) of the composite sheet can be in the range of 50 to 90 (Shore A)/(K/W). More preferably, the (Shore A hardness)/(thermal resistance) can be in the range of 58 to 86 (Shore A)/(K/W), and most preferably, 78 to 86 (Shore A)/(K/W). The thermal resistance and workability characteristics can be obtained without increasing the yield within the above range.

In the composite sheet of the above embodiment, a conductive layer is formed on the above primer layer, and the above conductive layer includes a carbon-based compound and a polymer binder. The above carbon-based compound is a raw material with thermal conductivity and electrical conductivity, and the above polymer binder is a raw material that helps the bonding between the carbon-based compounds or helps the bonding between the conductive layer and the primer layer.

The composite sheet includes a carbon-based compound with thermal conductivity and electrical conductivity. It has excellent thermal conductivity and electrical conductivity. When the composite sheet is used as a heat sink for various electrical and electronic process equipment including semiconductor process equipment, it can quickly transfer heat to solve the problem of local heat concentration and prevent electromagnetic instability such as electrification caused by plasma.

The conductive layer includes a carbon-based compound and a polymer binder. The weight ratio of the carbon-based compound to the polymer binder is preferably 1:0.2 to 30, more preferably 1:0.5 to 15, and most preferably 1:1 to 2. When the weight ratio of the carbon-based compound to the polymer binder is less than 1:0.2, the bonding force between the polymer binder and the primer layer decreases, and delamination may occur. Since the binder cannot bond the carbon-based compound, fillers may be bonded to the surface. When the weight ratio of the carbon-based compound to the polymer binder is greater than 1:30, the polymer binder content is too high, which may reduce thermal conductivity and electrical conductivity.

The maximum diameter of the particles of the carbon-based compound is not particularly limited, but in order to prevent the thickness of the conductive layer from becoming too thick and to make the thickness of the conductive layer uniform, the maximum diameter of the particles of the carbon-based compound is preferably 0.01 to 100 μm, more preferably 0.1 to 70 μm, and most preferably 0.5 to 50 μm.

The carbon-based compound included in the conductive layer may include one or more selected from the group consisting of carbon black, graphite, carbon nanotubes (CNT), graphene, graphene oxide, carbon fiber, fullerene, carbon, nanocarbon, and carbon black. By including such a carbon-based compound, the conductive layer may exhibit high conductivity characteristics in the vertical and horizontal directions on one side thereof. Preferably, the carbon-based compound included in the conductive layer may include graphite. Individual particles of such graphite may be flake-shaped, with a maximum diameter of 0.01 to 100 μm and a density of 1.5 to 3.0 g/cc.

Preferably, the polymer adhesive uses a substance with excellent electrical conductivity and impact absorption properties. Specific examples of substances that can be used as such polymer adhesives include one or more selected from the group consisting of thermosetting silicone rubber compounds, one-component thermosetting silicone adhesives, two-component thermosetting silicone adhesives, acrylic resins, epoxy resins, urethane resins and urea resins. Such substances do not require a separate adhesive layer due to their excellent adhesive strength, which can simplify the work process and reduce the production cost of the final product.

The feature of the present invention is that the polymer adhesive includes a main agent, a curing agent and a filler. In addition, it may also include additives such as a tackifier, a coupling agent, and a pigment. The weight ratio of the main agent and the curing agent of the present invention can be 1:0.6 to 1.2, and more preferably 1:0.9 to 1.2.

In one embodiment of the polymer adhesive of the present invention, the main agent can be a compound including a vinyl group, and the curing agent can use a compound including a hydrogen group. Preferably, the main agent can use a compound represented by Chemical Formula 1, and the curing agent can use a compound represented by Chemical Formula 2.

Chemical formula 1

(where n1 is an integer between 10 and 150.)

(where n2 is an integer between 10 and 150.)

The vinyl group of the main agent and the hydrogen group of the curing agent react with the aid of heat or light to crosslink to increase hardness, which is preferred from the viewpoint of thermal resistance. For example, the bonding reaction of the vinyl group of the compound represented by Chemical Formula 1 and the hydrogen group of the compound represented by Chemical Formula 2 can be represented by Chemical Formula 3.

(Where n1 is an integer between 10 and 150, and n2 is an integer between 10 and 150.)

The composite sheet of the present invention allows the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 to react to include the compound represented by Chemical Formula 3, and can have excellent properties from the perspectives of thermal conductivity and workability.

The average density of the conductive layer of the composite sheet included in the above embodiment can be 1.0 to 5.0 g/cc. When the average density of the conductive layer is less than 1.0 g/cc, the thermal conductivity and electrical conductivity may decrease. When the average density of the conductive layer is greater than 5.0 g/cc, the coating strength may decrease and the flexibility of the composite sheet may decrease.

The higher the density of the conductive layer, the lower the content of pores in the conductive layer. For example, the porosity of the conductive layer may be 5.0% or less. When the porosity of the conductive layer is greater than 5.0%, the coating strength, thermal conductivity and electrical conductivity may decrease.

On the other hand, the thickness of the conductive layer may preferably be 5 to 400 μm, more preferably 10 to 300 μm, and most preferably 80 to 150 μm. When the thickness of the conductive layer is less than 5 μm, the supporting force of the composite sheet may be reduced due to the inclusion of an excessively thin conductive layer. When the thickness of the conductive layer is greater than 400 μm, the flexibility of the composite sheet is reduced due to the inclusion of an excessively thick conductive layer, and the thermal conductivity and electrical conductivity are reduced.

(Implementation example)

A primer layer was applied on aluminum with a thickness of 40 μm as a substrate, and a conductive coating liquid composition was applied thereon to form a conductive layer, and a composite sheet with a total thickness of 152 μm was manufactured. The Shore hardness (Shore A) was measured under the condition that the entire test piece was 1 mm thick, the thermal resistance was measured in a DynTIMS device at 1100 kPa, and the wear resistance was measured using a Taber abrasion tester CS-10 wheel at 50 rpm/500 cycles. Filler 1 uses natural graphite powder with an average fineness (D50) of 10μm, filler 2 uses spherical alumina (Al2O3) powder with an average fineness (D50) of 10μm, and filler 3 uses nickel-coated copper powder with an average fineness (D50) of 10μm. The main agent uses a compound represented by chemical formula 1 (n1 is 135), and the curing agent uses a compound represented by chemical formula 2 (n2 is 84). Additives are mixed with epoxysilane-based viscosity enhancers, methylsilane-based coupling agents, and carbon black pigments in a weight ratio of 1:1:0.5. In the composite sheets of the embodiments and comparative examples, the other conditions are kept the same, and the conditions of the conductive layer are changed to conduct experiments.

Table 1 is a graph showing Shore hardness (A), thermal resistance (B), wear resistance, and the ratio of Shore hardness to thermal resistance (A/B) when the ratio of the main agent to the curing agent is changed.

As shown in Table 1, it can be seen that Examples 1 to 6 exhibit superior properties in Shore hardness, thermal resistance, and wear resistance compared to Comparative Examples 1 to 3.

Table 2 is a graph showing the Shore hardness (A), thermal resistance (B), wear resistance, and the ratio of Shore hardness to thermal resistance (A/B) when the ratio of the main agent to the curing agent is changed in various conductive layer densities.

As shown in Table 2, it can be seen that Examples 7 to 9 exhibit superior properties in Shore hardness, thermal resistance, and wear resistance compared to Comparative Examples 4 to 9.

Table 3 is a graph showing Shore hardness (A), thermal resistance (B), wear resistance, and the ratio of Shore hardness to thermal resistance (A/B) when the ratio of the main agent to the curing agent is changed in various porosities.

As shown in Table 3, it can be seen that Examples 10 to 12 exhibit superior properties in Shore hardness, thermal resistance, and wear resistance compared to Comparative Examples 10 to 15.

The present invention is not limited to the above-mentioned embodiments and can be manufactured in various forms. Ordinary technicians in the technical field to which the present invention belongs should understand that it can be implemented in other specific forms without changing the technical ideas or necessary features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all aspects, not limiting.

Claims (8)

A composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, comprising: a substrate; a primer layer formed on at least one side of the substrate; and a conductive layer formed on the upper part of the primer layer, comprising a carbon-based compound and a polymer binder, and having a Shore A hardness ranging from 50 to 95 Shore A; wherein the polymer binder comprises a main agent, a curing agent and a filler, and the main agent The weight ratio of the main agent to the curing agent is 1:0.6 to 1.2, the main agent is a compound including vinyl, the curing agent is a compound including hydrogen, the vinyl of the main agent and the hydrogen of the curing agent react to crosslink, and the carbon-based compound includes one or more selected from the group consisting of graphite, carbon nanotubes, graphene, graphene oxide, carbon fiber, fullerene, carbon, nanocarbon, and carbon black. As claimed in claim 1, the composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, wherein the weight ratio of the carbon-based compound to the polymer binder is 1:0.2 to 30. A composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment as claimed in claim 1, wherein the polymer adhesive is one or more selected from the group consisting of thermosetting silicone rubber compounds, one-component thermosetting silicone adhesives, two-component thermosetting silicone adhesives, acrylic resins, epoxy resins, urethane resins and urea resins. As claimed in claim 1, a composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, wherein the thickness of the conductive layer is 5 to 450 μm. As claimed in claim 1, the composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, wherein the average density of the conductive layer is 1.0 to 5.0 g/cc. A composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment as claimed in claim 1, wherein the porosity of the conductive layer is less than 5%. As claimed in claim 1, a composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, wherein the thermal resistance of the composite sheet is in the range of 0.8 to 1.3K/W. As claimed in claim 1, a composite sheet with excellent thermal conductivity and electrical conductivity suitable for plasma process equipment, wherein the ratio of (Shore A hardness)/(thermal resistance) of the composite sheet is in the range of 50 to 90 (Shore A)/(K/W).