A method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck

Abstract

The invention discloses a method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck, and the steps are as follows: obtaining a hyperbranched polyurethane (HBPU) solution with a hyperbranching degree of 0.6; obtaining a hydroxyl-terminated hyperbranched organic silica gel solution; preparing a high molecular weight modified siliconized polyurethane rubber bottom layer solution; using an appropriate amount of silane coupling agent (KH550) to carry out surface modification treatment with aluminum oxide nanopowder, aluminum nitride nanopowder, white carbon black nanopowder, and diamond-like carbon nanopowder respectively by a liquid phase modification method, and then obtaining a modified material by a spray drying method; preparing a high molecular weight modified siliconized polyurethane bottom layer solution; preparing a high molecular weight modified siliconized polyurethane dielectric layer and an electrode layer; preparing a thermally conductive insulating layer; and patterning a dielectric substrate B electrode layer. The electrostatic chuck prepared by the invention has high tolerance to temperature difference, clean, flexible clamping functions, and has higher mechanical strength, thermal stability, and temperature zone adaptability.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor and flat panel display manufacturing, and specifically relates to a manufacturing method of a high molecular weight modified siliconized polyurethane electrostatic chuck. Background Art

[0002] Electrostatic chucks are one of the key core components in semiconductor and flat panel display manufacturing process equipment. In wafer processing equipment, such as photolithography, plasma etching, ion implantation, vapor deposition, resist stripping and vacuum ion beam testing. The types of equipment required for these processes include various functional components located in vacuum chambers with plasma and halogen. These functional components must operate stably and reliably for thousands of cycles while maintaining full functionality and cleanliness. Among them, the electrostatic chuck is a key component that clamps the semiconductor wafer or other workpiece being processed in the vacuum chamber and keeps it in a fixed position.

[0003] From the perspective of mechanical model, the existing mainstream ceramic electrostatic chucks are divided into two types: Coulomb force and Jungian thermal back (JR). The electrostatic chuck in the cavity is connected to the electrostatic chuck power supply outside the cavity through a high-voltage connection component set on the vacuum chamber. When the processing equipment is running, such as plasma etching, ion implantation, and vapor deposition processes, the external high-voltage DC power supply is continuously powered to clamp the wafer in a fixed position. The principle of electrostatic clamping generated by the electrostatic chuck is well known, so this article will not describe it in detail.

[0004] From the perspective of ceramic materials, mainstream ceramic electrostatic chucks are divided into two types: alumina ceramics or aluminum nitride ceramics. Alumina ceramics or aluminum nitride ceramics are co-fired with metals such as tungsten or molybdenum arranged inside the ceramic layer through processes such as hot isostatic pressing. After sintering, the ceramic composite sheet is processed by a series of high-precision CNC centers. The preparation methods of alumina ceramic electrostatic chucks and aluminum nitride ceramic electrostatic chucks are well known, so this article will not describe them in detail.

[0005] In addition, with the rapid development of semiconductor technology, integrated circuit chips are becoming thinner and thinner. Due to the reduction in mechanical strength of thin wafers, it is more difficult to perform secondary thinning and remove particles and metal element residues. In order to solve the problem of metal element and particle contamination on the back of the chip caused by the ceramic electrostatic chuck during long-term use in a plasma gas environment, processes such as DLC coating (diamond-like carbon) are used on the surface of the ceramic electrostatic chuck. However, the diamond-like surface coating is hard and can easily cause secondary damage to the back of the thin chip, with a greater risk of fragmentation and damage.

[0006] In addition, the high molecular weight modified siliconized polyurethane material prepared by the published patent [CN202111552045.6] has strong initial viscosity and cannot achieve rapid detachment of the chip; and the high molecular weight modified siliconized polyurethane material prepared in this way does not meet the requirements of electrostatic chuck use in terms of thermal conductivity, thermal stability, mechanical strength, insulation resistance, dielectric constant and other indicators.

[0007] Therefore, in order to adapt to the more advanced development of integrated circuit technologies such as etching and ion implantation, an electrostatic chuck structure with high tolerance to temperature difference, cleanliness, and flexible clamping functions is necessary. Summary of the invention

[0008] In order to overcome the shortcomings of the current electrostatic chuck caused by uneven thermal expansion coefficient and precipitation of elemental substances, the present invention provides a method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck. The prepared electrostatic chuck dielectric layer has a higher dielectric constant and a stable molecular structure, as well as a thermal expansion coefficient similar to that of other component layers; it can ensure that the thermal conductive insulation layer has a higher mechanical strength; it has high tolerance to temperature difference, cleanliness, and flexible clamping functions; and by using a thermal conductive insulation layer with a thermal expansion coefficient and Rockwell hardness similar to those of the dielectric layer to combine various key components, the electrostatic chuck has higher thermal stability and a temperature zone adaptability range.

[0009] The present invention provides the following technical solution: a method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck, the steps are as follows:

[0010] Step 1: obtaining a hyperbranched polyurethane (HBPU) solution having a hyperbranching degree of 0.6 by a known method;

[0011] Step 2: obtaining a hydroxyl-terminated hyperbranched organic silica gel solution by a known method;

[0012] Step 3: preparing a high molecular weight modified siliconized polyurethane rubber bottom layer solution;

[0013] Step 4: using a known method, using an appropriate amount of silane coupling agent (KH550) to carry out surface modification treatment with alumina nanopowder, aluminum nitride nanopowder, white carbon nanopowder, and diamond-like carbon nanopowder respectively by a liquid phase modification method, and then obtaining a modified material by a spray drying method;

[0014] Step 5: preparing a high molecular weight modified siliconized polyurethane bottom layer solution;

[0015] Step 6: preparing a high molecular weight modified siliconized polyurethane dielectric layer and an electrode layer;

[0016] Step 7: preparing a thermally conductive insulating layer;

[0017] Step 8: Patterning of the electrode layer of the dielectric substrate B.

[0018] Preferably, the step three comprises:

[0019] 1) Adding an appropriate amount of polydimethylsiloxane to a high molecular weight modified siliconized polyurethane synthesized by catalysis of lithium siloxane alcohol;

[0020] 2) Adding polydimethylsiloxane can reduce the surface tension and viscosity of high molecular weight modified siliconized polyurethane liquid.

[0021] Preferably, in step 4, a proper amount of silane coupling agent (KH550) and white carbon black nanopowder are used for surface modification by surface grafting, so as to prepare KH550@white carbon black (KH550-SiO2) with high crosslinking density, uniform filler dispersion, high wear resistance and strong thermal stability.

[0022] Preferably, the specific steps of step 5 are as follows:

[0023] 1) Take appropriate amount of hyperbranched polyurethane (HBPU) solution and hydroxyl-terminated hyperbranched organic silica gel solution, add them into a beaker filled with nitrogen, stir for a certain time, and carry out polymerization reaction at room temperature to obtain high molecular weight modified siliconized polyurethane bottom layer solution A;

[0024] 2) Take an appropriate amount of KH550@white carbon black (KH550-SiO 2 )、KH550@alumina(KH550-Al 2 O 3 ), KH550@diamond-like carbon, etc., one or more thereof are added to the high molecular weight modified siliconized polyurethane bottom layer solution A, and the mixed solution is placed in a vacuum stirring and defoaming device for not less than 60 minutes of stirring and defoaming treatment, and the vacuum degree during defoaming is not less than 2000Pa;

[0025] 3) A high molecular weight modified siliconized polyurethane bottom mixed solution synthesized by adding modified nano-powder catalysis, i.e., dielectric solution C;

[0026] 4) The obtained dielectric solution C has the characteristics of high density, wear resistance, thermal stability, dielectric constant, etc., and the dielectric constant is not less than 10, which is one of the ideal dielectric materials for electrostatic chucks.

[0027] Preferably, the specific steps of step six are as follows:

[0028] 1) The dielectric solution C is uniformly coated on the metal foil after plasma modification by a known method to prepare a dielectric substrate B. The dielectric solution C and the metal foil can be coated by roller coating, casting, spraying, etc. The metal foil is preferably an electrolytic copper foil with a thickness of 50 microns;

[0029] 2) Then, the dielectric substrate B is subjected to high-temperature vulcanization treatment in a vacuum atmosphere by a known method, wherein the vulcanization temperature is not less than 230° C.;

[0030] 3) The thickness of the dielectric layer of the prepared dielectric substrate B is not less than 0.1 mm;

[0031] 4) The dielectric substrate B non-metal is treated with polydimethylsiloxane again to further reduce the non-metal surface tension of the dielectric substrate B.

[0032] Preferably, the specific steps of step seven are as follows:

[0033] 1) By increasing or decreasing the type or dosage of modified nano-powder in the high molecular weight modified siliconized polyurethane bottom layer solution, a high molecular weight modified siliconized polyurethane bottom layer mixed solution, i.e., a thermal conductive insulating solution D, is obtained;

[0034] 2) The thermally conductive insulating solution D is introduced into an unmarked mold, and an electronic glass fiber mesh layer is suspended in the mold, and vacuum degassing is performed, and the vacuum degree in the cavity is not less than 10 to the negative 3rd power;

[0035] 3) The thermally conductive insulating solution D completely covers the electronic glass fiber mesh layer. After curing, the electronic glass fiber mesh layer is located in the middle of the thermally conductive insulating layer.

[0036] Preferably, the specific steps of step eight are as follows:

[0037] 1) Generate a conductive line of a specific pattern on the metal side of the dielectric substrate B by a known method, such as wet etching;

[0038] 2) Vacuum bonding the dielectric substrate B with the formed circuit structure and the thermally conductive insulating substrate B. After the cross-linking reaction, the thermally conductive insulating layer completely wraps the electrode layer of the dielectric substrate B, and has a dense structure to form a composite material F;

[0039] 3) Cutting the composite material F into a specific shape and structure;

[0040] 4) Vacuum bonding the composite material F having a specific external structure to the metal base layer.

[0041] Preferably, the thermally conductive insulating layer and the metal base are components with different thermal expansion coefficients and relatively large areas, so as to achieve bonding and adhesion at a relatively high temperature.

[0042] Preferably, the metal base is made of several pieces of aluminum and is machined on the top layer, and then assisted by one or more processes such as brazing, friction stir welding, and ion beam welding to complete the internal heat dissipation channel of this layer.

[0043] The dielectric layer of the electrostatic chuck prepared by the present invention has a high dielectric constant and a stable molecular structure, as well as a thermal expansion coefficient similar to that of other component layers; it can ensure that the thermally conductive insulating layer has a high mechanical strength; it has high tolerance to temperature differences, cleanliness, and flexible clamping functions; and by combining various key components using a thermally conductive insulating layer with a thermal expansion coefficient and Rockwell hardness similar to that of the dielectric layer, the electrostatic chuck has higher thermal stability and a temperature zone adaptability range. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic cross-sectional view of an electrostatic chuck prepared in the present invention;

[0045] In the figure, 100 is a dielectric layer, 200 is an electrode layer, 300 is a thermally conductive insulating layer, 400 is an electronic glass fiber mesh layer, and 500 is a metal base layer. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below through examples and drawings. The raw materials used in the examples can be purchased from the market or prepared by known conventional methods. Example

[0047] A method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck, the steps are as follows:

[0048] Step 1: Obtain a hyperbranched polyurethane (HBPU) solution with a hyperbranching degree of 0.6 by a known method.

[0049] Step 2: Obtain a hydroxyl-terminated hyperbranched organic silica gel solution by a known method.

[0050] Step 3: Prepare a high molecular weight modified siliconized polyurethane rubber base layer solution.

[0051] 1) Adding an appropriate amount of polydimethylsiloxane to the high molecular weight modified siliconized polyurethane synthesized by siloxane lithium catalysis.

[0052] 2) Adding polydimethylsiloxane can reduce the surface tension and viscosity of high molecular weight modified siliconized polyurethane liquid.

[0053] Step 4: Using a known method, a suitable amount of silane coupling agent (KH550) is used to carry out surface modification treatment with alumina nanopowder, aluminum nitride nanopowder, white carbon nanopowder, and diamond-like carbon nanopowder respectively by liquid phase modification method, and then the modified material is obtained by spray drying.

[0054] In this embodiment, white carbon black nanopowder is taken as an example. By using an appropriate amount of silane coupling agent (KH550) and alumina nanopowder for surface modification, KH550@white carbon black (KH550-SiO2) with high cross-linking density, uniform filler dispersion, high wear resistance and strong thermal stability can be prepared.

[0055] Step 5: Preparation of high molecular weight modified siliconized polyurethane bottom layer solution:

[0056] 1) Take appropriate amounts of hyperbranched polyurethane (HBPU) solution and hydroxyl-terminated hyperbranched organic silica gel solution, add them into a beaker filled with nitrogen, stir for a certain period of time, and perform polymerization reaction at room temperature to obtain a high molecular weight modified siliconized polyurethane base layer solution A.

[0057] 2) Take an appropriate amount of KH550@white carbon black (KH550-SiO 2 )、KH550@alumina(KH550-Al 2 O 3 ), KH550@diamond-like carbon, etc., one or more thereof are added to the high molecular weight modified siliconized polyurethane bottom layer solution A, and the mixed solution is placed in a vacuum stirring and defoaming device for stirring and defoaming treatment for not less than 60 minutes, and the vacuum degree during defoaming is not less than 2000Pa.

[0058] 3) A high molecular weight modified siliconized polyurethane bottom layer mixed solution synthesized by adding modified nano-powder catalyst, namely dielectric solution C.

[0059] 4) The obtained dielectric solution C has the characteristics of high density, wear resistance, thermal stability, dielectric constant, etc., and the dielectric constant is not less than 10, which is one of the ideal dielectric materials for electrostatic chucks.

[0060] Step 6: Prepare a high molecular weight modified siliconized polyurethane dielectric layer 100 and an electrode layer 200 .

[0061] 1): The dielectric solution C is uniformly coated on the metal foil after plasma modification by a known method to prepare a dielectric substrate B. The dielectric solution C and the metal foil can be coated by roller coating, casting, spraying, etc. In this embodiment, the metal foil is preferably an electrolytic copper foil with a thickness of 50 microns.

[0062] 2): The dielectric substrate B is subjected to a high-temperature vulcanization treatment in a vacuum atmosphere in a known manner, and the vulcanization temperature is not less than 230°C.

[0063] 3): The thickness of the dielectric layer of the prepared dielectric substrate B is not less than 0.1 mm.

[0064] 4): The dielectric substrate B non-metal is treated with polydimethylsiloxane again to further reduce the non-metal surface tension of the dielectric substrate B.

[0065] Step 7: Thermally conductive insulation layer 300 .

[0066] 1) By increasing or decreasing the type or dosage of modified nano-powder in the high molecular weight modified siliconized polyurethane bottom layer solution, a high molecular weight modified siliconized polyurethane bottom layer mixed solution, namely, a thermal conductive insulating solution D, is obtained.

[0067] 2) The thermally conductive insulating solution D is introduced into an unmarked mold, and an electronic glass fiber mesh layer is suspended in the mold, and vacuum degassing is performed, and the vacuum degree in the cavity is not less than 10 to the negative power of 3.

[0068] 3) The thermally conductive insulating solution D completely covers the electronic glass fiber mesh layer 400. After curing, the electronic glass fiber mesh layer 400 is located in the middle of the thermally conductive insulating layer 300.

[0069] Step 8: Patterning of the dielectric substrate B electrode layer 200.

[0070] 1) Generate a conductive line of a specific pattern on the metal side of the dielectric substrate B by a known method, such as wet etching.

[0071] 2) The dielectric substrate B with the formed circuit structure is vacuum bonded with the thermally conductive insulating substrate B. After the cross-linking reaction, the thermally conductive insulating layer 300 completely wraps the electrode layer 200 of the dielectric substrate B, and has a dense structure, thereby manufacturing a composite material F.

[0072] 3) Cutting the composite material F into specific shapes and structures.

[0073] 4) The composite material F having a specific external structure is vacuum bonded to the metal base layer 500 .

[0074] 5) Continuing with the above embodiment, the thermally conductive insulating layer 300 and the metal base 500 are components with different thermal expansion coefficients and relatively large areas. In this embodiment, bonding and adhesion are achieved at a relatively high temperature.

[0075] The metal base 500 is made of several pieces of aluminum and is machined on the top layer, and then assisted by one or more processes such as brazing, friction stir welding, and ion beam welding to complete the internal heat dissipation channel of this layer.

[0076] In the above embodiments, the preparation methods of the main functional components of the electrostatic chuck are similar, and the thermal stability and thermal linear expansion coefficient reach the best matching value. It is not limited to being close in thermal expansion coefficient, and the heat transfer rate is significantly improved compared with the current electrostatic chuck, reducing the difference in thermal expansion coefficient, further improving the overall tolerance temperature range of the electrostatic chuck and reducing the precipitation of contact surface elements and particulate matter in the plasma atmosphere. Example

[0077] See also Figure 1 The present invention prepares a high molecular weight modified siliconized polyurethane electrostatic chuck, whose assembly structure is in the form of a combination of multi-layer functional components, and its main material components are high molecular weight modified siliconized polyurethane, aluminum oxide nano-powder, etc. The functional components include a dielectric layer, an electrode layer, a thermally conductive insulating layer and a mounting base layer. The dielectric layer is composited with non-metallic materials containing high molecular weight modified siliconized polyurethane, aluminum oxide nano-powder, aluminum nitride nano-powder, white carbon nano-powder, diamond-like nano-powder, etc. The material has a high dielectric constant and a stable molecular structure, as well as a thermal expansion coefficient similar to that of other component layers, thereby overcoming the shortcomings of the current electrostatic chuck caused by uneven thermal expansion coefficients and precipitation of elemental substances.

[0078] In this embodiment, the thermally conductive insulating layer is composed of a high molecular weight modified siliconized polyurethane layer with high impedance and thermal conductivity, and an electronic glass fiber mesh layer with a stable structure arranged in the high molecular weight modified siliconized polyurethane layer; this structure can ensure that the thermally conductive insulating layer has high mechanical strength.

[0079] In this embodiment, the main component of the thermally conductive insulating layer is one or more of high molecular weight modified siliconized polyurethane, aluminum oxide nanopowder, aluminum nitride nanopowder, etc., and the preparation method is similar to that of the dielectric layer. By using a thermally conductive insulating layer with a thermal expansion coefficient and Rockwell hardness similar to those of the dielectric layer to combine various key components, the electrostatic chuck has higher thermal stability and temperature adaptability range.

[0080] Although specific embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck, characterized in that: Here are the steps: Step 1: obtaining a hyperbranched polyurethane solution with a hyperbranching degree of 0.6; Step 2: obtaining a hydroxyl-terminated hyperbranched organic silica gel solution; Step 3: preparing a high molecular weight modified siliconized polyurethane rubber bottom layer solution; Step 4: using an appropriate amount of silane coupling agent to carry out surface modification treatment with alumina nanopowder, aluminum nitride nanopowder, white carbon nanopowder and diamond-like carbon nanopowder respectively by a liquid phase modification method, and then obtaining a modified material by a spray drying method; Step 5: preparing a high molecular weight modified siliconized polyurethane bottom layer solution; Step 6: preparing a high molecular weight modified siliconized polyurethane dielectric layer and an electrode layer; Step 7: preparing a thermally conductive insulating layer; Step 8: Patterning of the electrode layer of the dielectric substrate B; The step three comprises: 1) Adding an appropriate amount of polydimethylsiloxane to a high molecular weight modified siliconized polyurethane synthesized by catalysis of lithium siloxane alcohol; 2) Adding polydimethylsiloxane can reduce the surface tension and viscosity of high molecular weight modified siliconized polyurethane liquid.

2. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 1, characterized in that: In the step 4, a proper amount of silane coupling agent and white carbon black nano powder are used for surface modification treatment to prepare KH550@white carbon black.

3. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 1, characterized in that: The specific steps of step 5 are as follows: 1) Take appropriate amounts of hyperbranched polyurethane solution and hydroxyl-terminated hyperbranched organic silica gel solution, add them into a beaker filled with nitrogen, stir for a certain period of time, and carry out polymerization reaction at room temperature to obtain a high molecular weight modified siliconized polyurethane bottom layer solution A; 2) Take an appropriate amount of one or more of KH550@white carbon black, KH550@alumina, and KH550@diamond-like carbon and add them to the high molecular weight modified siliconized polyurethane bottom layer solution A, and place the mixed solution in a vacuum stirring and defoaming device for no less than 60 minutes, and the vacuum degree during defoaming is no less than 2000Pa; 3) A high molecular weight modified siliconized polyurethane bottom layer mixed solution synthesized by adding modified nano-powder catalyst, namely dielectric solution C.

4. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 1, characterized in that: The specific steps of step six are as follows: 1) The dielectric solution C is evenly coated on the plasma-modified metal foil to prepare a dielectric substrate B. The dielectric solution C and the metal foil can be coated by roller coating, casting, or spraying. The metal foil is a 50-micron thick electrolytic copper foil; 2) Performing high-temperature vulcanization treatment on the dielectric substrate B in a vacuum atmosphere, with the vulcanization temperature being not less than 230°C; 3) The thickness of the dielectric layer of the prepared dielectric substrate B is not less than 0.1 mm; 4) The dielectric substrate B non-metal is treated with polydimethylsiloxane again to further reduce the non-metal surface tension of the dielectric substrate B.

5. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 3, characterized in that: The specific steps of step seven are as follows: 1) By increasing or decreasing the type or dosage of modified nano-powder in the high molecular weight modified siliconized polyurethane bottom layer solution, a high molecular weight modified siliconized polyurethane bottom layer mixed solution, i.e., a thermal conductive insulating solution D, is obtained; 2) The thermally conductive insulating solution D is introduced into an unmarked mold, and an electronic glass fiber mesh layer is suspended in the mold, and vacuum degassing is performed, and the vacuum degree in the cavity is not less than 10 to the negative 3rd power; 3) The thermally conductive insulating solution D completely covers the electronic glass fiber mesh layer. After curing, the electronic glass fiber mesh layer is placed in the middle of the thermally conductive insulating layer.

6. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 1, characterized in that: The specific steps of step eight are as follows: 1) Use wet etching to generate a conductive circuit with a specific pattern on the metal side of the dielectric substrate B; 2) Vacuum bonding the dielectric substrate B with the formed circuit structure and the thermally conductive insulating substrate B. After the cross-linking reaction, the thermally conductive insulating layer completely wraps the electrode layer of the dielectric substrate B, and has a dense structure to form a composite material F; 3) Cutting the composite material F into a specific shape and structure; 4) Vacuum bonding the composite material F having a specific external structure to the metal base layer.

7. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 6, characterized in that: The heat-conducting insulating layer and the metal base are components with different thermal expansion coefficients and relatively large areas, so that bonding and adhesion can be achieved at a relatively high temperature.

8. The method for manufacturing a high molecular weight modified siliconized polyurethane electrostatic chuck according to claim 7, characterized in that: The metal base is made of several pieces of aluminum and is machined on the top layer, and then assisted by one or more processes such as brazing, friction stir welding, and ion beam welding to complete the internal heat dissipation water channel of this layer.

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