Manufacturing method of electrostatic chuck

Abstract

The invention discloses a manufacturing method of an electrostatic chuck. The electrostatic chuck comprises an electrostatic chuck main body, a dielectric medium, an electrode group and a metal base, the manufacturing method comprises the following steps of: 1, completing an inactive gas channel and a cooling liquid channel in the metal base; 2, a gas channel vertically penetrates through three gas channel holes in the electrostatic chuck main body and is communicated with the wafer and the edge gas sealing ring; thirdly, on the electrostatic chuck body, a cooling channel transversely penetrates through a cooling liquid input port and a cooling liquid output port; the temperature and flow velocity of the cooling liquid are controlled through an external system to achieve the effect of balancing the temperature of the electrostatic chuck main body; and 4, after the wafer is carried on the dielectric medium, applying direct high voltage to the positive and negative electrode groups, and adsorbing the wafer on the gas sealing ring and the micro-boss which are arranged on the edge of the dielectric medium. According to the invention, an inert gas atmosphere space formed by the gas sealing ring and the wafer at the outer edge of the high-cleanliness electrostatic chuck is realized.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor and flat panel display manufacturing, and in particular relates to a manufacturing method of an electrostatic chuck. Background Art

[0002] In order to obtain the desired wafer pattern structure in the semiconductor manufacturing process, the wafer is subjected to ion implantation and etching, PVD and CVD film formation and other processes. In the vacuum processing device for performing these processes, an electrostatic chuck is installed to fix the wafer in a processing chamber in a vacuum atmosphere. In the known literature, an electrode is pre-embedded inside the main dielectric of the electrostatic chuck, and a high voltage is applied externally to generate a clamping force on the wafer.

[0003] As is known to all, during the processing in the above vacuum processing device, there will be temperature deviation, and in more advanced processes, the chip is sometimes controlled within a specified temperature range. In this case, if the temperature is lower than the set value, a resistive heating plate will be provided inside the electrostatic chuck to provide the necessary heat; if cooling is required, an inactive gas is supplied to the internal space formed by the chip and the clamping surface of the electrostatic chuck through the gas channel provided in the main body of the electrostatic chuck. The inactive gas atmosphere space composed of the gas sealing ring on the outer edge of the electrostatic chuck and the chip will accelerate the heat conduction from the electrostatic chuck to the chip, thereby providing stable and accurate temperature control for the chip.

[0004] In addition, in order to realize the inactive gas atmosphere space composed of the gas sealing ring on the outer edge of the electrostatic chuck and the wafer, a high-impedance ceramic sheet such as aluminum nitride or silicon nitride is usually used as the dielectric layer for the electrostatic chuck, and a gas sealing ring is formed on the ceramic sheet in a known manner, as well as several micro-convex structures that reduce the contact between the wafer and the ceramic sheet. However, in order to maintain the stable clamping effect of the wafer without increasing the clamping voltage, the gas sealing ring and the micro-convex need to be processed to an ideal surface finish.

[0005] However, after the high voltage is stopped from being applied to the electrostatic chuck, the residual charge of aluminum nitride or aluminum nitride ceramics produced by high-temperature co-firing is polished or ground, and the chip cannot be quickly and stably detached due to the residual charge. The aluminum nitride or aluminum nitride ceramics are repeatedly clamped or released in the vacuum processing device, and the surface of the ceramics after plane polishing or grinding will be physically and chemically eroded, and aluminum nitride or aluminum nitride particles will be precipitated locally on the surface. These particles are transformed into an electrically suspended state, which makes it impossible to quickly release the residual polarized charge between the ceramic surface and the chip. In addition, these suspended particles and metal elements will adhere to the back of the chip, causing chip contamination and irreversible damage.

[0006] In addition, using high-impedance, corrosion-resistant, low-outgassing materials such as polyimide as the dielectric layer of the electrostatic chuck can eliminate the contamination of the back of the chip by suspended ions and elements on the surface of the dielectric layer. However, if the above-mentioned inactive gas atmosphere space composed of the gas sealing ring on the outer edge of the electrostatic chuck and the chip is to be realized, it is limited by the constraints of material processing and performance, and it is impossible to accelerate the thermal conductivity performance from the electrostatic chuck to the chip to provide a sufficiently stable temperature control function for the chip. Summary of the invention

[0007] In order to solve the defects and shortcomings in the above-mentioned prior art, the present invention provides a method for manufacturing an electrostatic chuck having an inactive gas atmosphere space composed of an edge gas sealing ring and a chip, by realizing an edge gas sealing ring and a micro-boss structure in a polymer dielectric layer. The heat conduction in the plane direction of the electrostatic chuck can further improve the temperature uniformity and cleanliness on the chip, and the method has the capability of realizing an inactive gas atmosphere space composed of an edge gas sealing ring and a chip outside the electrostatic chuck with high cleanliness.

[0008] The present invention provides the following technical solution: a method for manufacturing an electrostatic chuck, the electrostatic chuck comprising an electrostatic chuck body, a dielectric, an electrode group, and a metal base; the manufacturing steps are as follows: Step 1: The metal base is made of several pieces of aluminum alloy and subjected to multiple machining processes, and then assisted by one or more processes such as brazing, friction stir welding, and ion beam welding, so as to complete the inactive gas channel and coolant channel inside this layer; Step 2: On the main body of the electrostatic chuck, the gas channel runs through three gas channel holes from top to bottom and communicates with the wafer and the edge gas sealing ring; an inactive gas source is installed to introduce the inactive gas into the unmarked inactive gas atmosphere interval formed by the wafer and the edge gas sealing ring through the gas channel provided on the metal base, and the flow rate and flow velocity of the inactive gas are controlled by an external system to achieve the effect of balancing the wafer temperature; Step 3: On the electrostatic chuck body, a cooling channel is provided to horizontally penetrate the cooling input port and the coolant output port; the temperature and flow rate of the coolant are controlled by an external system to achieve the effect of balancing the temperature of the electrostatic chuck body; Step 4: After the chip is mounted on the dielectric, the positive and negative electrode groups apply direct high voltage and the chip is adsorbed on the edge gas sealing ring and micro-protrusion placed on the dielectric; at this time, the inactive gas atmosphere space is in a sealed state, and the external gas source inputs inactive gas through the heat dissipation air duct, and the three gas channel holes that pass through the top and bottom are filled with an appropriate amount of inactive gas into the inactive gas atmosphere space, which can enhance the temperature control of the chip.

[0009] Preferably, the dielectric uses an insulating material with a relatively high dielectric constant or a semiconductor material mixed with an insulator and a metal oxide, wherein the internal electrode group material is made of aluminum, copper or other conductive materials, and the metal base is made of aluminum alloy 6061-T651.

[0010] Preferably, the steps of manufacturing the dielectric are as follows: S1, preparing KH550@alumina powder by surface modification treatment, then adding an appropriate amount of KH550@alumina powder to a polyimide solution, and appropriately adding an organic binder or sintering aid that can improve the formability, and using a known vacuum thermoforming machine to cast / calender the stock solution Y into a thin sheet F having an ideal thermal conductivity, bulk resistivity, and surface morphology; S2, manufacturing electrode patterns on the formed sheet by screen printing, bonding, exposure or etching; after completing the plasma surface treatment, placing solution A in an unmarked vacuum mold, and injecting an appropriate amount of stock solution Y again, and performing secondary vacuum thermoforming machine casting / calendering sintering to prepare thin sheet F1; S3, through grinding, the surface of the thin sheet F1 that contacts the wafer W is flattened and mirror-polished to obtain an ideal structure; S4, preparation of an annular edge gas sealing ring and a plurality of micro bosses 400-1 disposed inside the edge gas sealing ring; S5, through grinding, the surface of the thin sheet F2 that contacts the wafer W is flattened and mirror-polished to obtain an ideal structure; the surface roughness of the annular edge gas sealing ring and the micro-protrusion is ≤Ra: 0.1μm and the flatness is ≤5μm.

[0011] Preferably, in step S3, an electrode pattern is manufactured on a molded sheet by silk screen printing, and a silk screen template without a specific pattern structure is used to print the stock solution Y onto the surface treated thin sheet F1, and the annular edge gas sealing ring and the micro-boss pattern structure are consistent, and vacuum heat sintering is performed again to prepare a thin sheet F2 having an annular edge gas sealing ring and a micro-boss pattern structure.

[0012] Preferably, the electrostatic chuck is used for a long time in a corrosive gas vacuum atmosphere without causing contamination of the back of the wafer by precipitation of suspended particles and metal elements, and has good cooling and temperature control performance for the wafer.

[0013] Preferably, the chip is arranged on an edge gas sealing ring and micro-bosses on the dielectric of the electrostatic chuck, and both are made of polyimide; the dielectric is made of polyimide material, and may include an annular edge gas sealing ring in contact with the circumferential edge surface of the back side of the chip and a plurality of micro-bosses arranged inside the edge gas sealing ring, forming a relatively closed inactive gas atmosphere space; the edge gas sealing ring is slightly higher than the micro-bosses and is in contact with the chip at the same time, jointly supporting the chip, and the presence of the micro-bosses maximizes the area of ​​the inactive gas atmosphere space, that is, increases the contact area between the inactive gas and the chip.

[0014] Preferably, a positive and negative electrode group is provided inside the dielectric, and a DC high voltage is applied to both ends of the positive and negative electrode group by an external high-voltage DC power supply.

[0015] Preferably, a metal oxide with a similar thermal expansion coefficient is added during the preparation of the dielectric; it includes alumina modified nanopowder, aluminum nitride modified nanopowder or diamond-like carbon modified nanopowder, wherein the content of alumina is not higher than 5%, and the thermal conductivity is not lower than 0.4 W / m·K, and the surface resistivity is not lower than 10 13 ohm / sq.

[0016] The present invention realizes an edge gas sealing ring and a micro-boss structure in a polymer dielectric layer to form an inactive gas atmosphere space composed of the edge gas sealing ring and the chip. The heat conduction in the plane direction of the electrostatic chuck can further improve the temperature uniformity and cleanliness on the chip, and has the effect of realizing an inactive gas atmosphere space composed of the edge gas sealing ring and the chip outside the high-cleanliness electrostatic chuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A cross-sectional schematic diagram of a device used in the manufacturing method of the present invention; Figure 2 It is a plane diagram of a part of the present invention enlarged to illustrate its manufacturing process; In the figure, W: chip, A: inactive gas source, P: high-voltage DC power supply, 100: dielectric, 200: electrode group, 200-1a: positive electrode, 200-1b: positive electrode, 200-2a: negative electrode, 200-2b: negative electrode, 300: metal base, 400: edge gas sealing ring, 400-1a: micro-boss, 400-1b: micro-boss; 400-1c: micro-boss; 500: gas channel; 500-a: gas channel hole; 500-b: gas channel hole; 500-c: gas channel hole; 600: cooling liquid channel; 600a: cooling liquid inlet; 600b: cooling liquid outlet. DETAILED DESCRIPTION

[0018] 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 1

[0019] The present embodiment provides a method for manufacturing an electrostatic chuck dielectric layer, an edge gas sealing ring and a micro-bump, the method having the function of realizing an inactive gas atmosphere space composed of a high-cleanliness electrostatic chuck outer edge gas sealing ring and a wafer.

[0020] In this embodiment, the main functional components of the electrostatic chuck include: dielectric 100, electrode group 200, and metal base 300. To manufacture dielectric 100, generally an insulating material with a relatively high dielectric constant or a semiconductor material mixed with an insulator and a metal oxide is used. In this embodiment, polyimide material is preferred. Among them, the material of the internal electrode group 200 is preferably aluminum (Al), copper (Cu), etc. or other conductive materials, and the metal base 300 is made of aluminum alloy 6061-T651.

[0021] like Figure 1 As shown, the wafer W is disposed on the edge gas sealing ring 400 and the micro-bump 400-1 on the electrostatic chuck dielectric 100, and both are made of polyimide. Figure 2 As shown, the dielectric 100 is made of, for example, a polyimide material, and may include an annular edge gas sealing ring 400 in contact with the circumferential edge surface of the back side of the wafer W and a plurality of micro bosses 400-1 disposed inside the edge gas sealing ring, thereby forming a relatively closed inert gas atmosphere space. The edge gas sealing ring 400 is slightly higher than the micro bosses 400-1. In actual cases, the edge gas sealing ring 400 is slightly higher than the micro bosses 400-1 and is in contact with the wafer W, thereby supporting the wafer W together. In addition, the presence of the micro bosses 400-1 maximizes the area of ​​the inert gas atmosphere space, that is, increases the contact area between the inert gas and the wafer W.

[0022] Positive and negative electrode groups 200 - 1 and 200 - 2 are provided inside the dielectric 100 , and a DC high voltage is applied to both ends of the positive and negative electrode groups by an external high-voltage DC power supply P.

[0023] In order to improve the thermal conductivity of the electrostatic chuck, a known preparation method is used to add metal oxides with similar thermal expansion coefficients during the preparation of the dielectric 100. By adding nanopowders such as aluminum oxide modified nanopowders, aluminum nitride modified nanopowders or diamond-like carbon modified nanopowders, wherein the content of aluminum oxide is not higher than 5%, the thermal conductivity is not lower than 0.4W / m·K, and the surface resistivity is not lower than 10 13 ohm / sq.

[0024] The metal base 300 is mainly made of aluminum alloy (6061-T651) with high mechanical strength. It is made of several pieces of aluminum alloy through multiple machining processes, and then assisted by one or more processes such as brazing, stir friction welding, and ion beam welding to complete the inactive gas channel 500 and the cooling liquid channel 600 inside this layer. On the main body of the electrostatic chuck, the gas channel 500 passes through the gas channel holes 500-a, 500-b, and 500-c from top to bottom, and is connected to the wafer W and the edge gas sealing ring 400. The inactive gas source A is installed to introduce the inactive gas into the unmarked inactive gas atmosphere interval formed by the wafer W and the edge gas sealing ring 400 through the gas channel 500 provided on the metal base 300, and the flow rate and flow rate of the inactive gas are controlled by the external system to achieve the effect of balancing the temperature of the wafer W.

[0025] As described above, on the electrostatic chuck body, the cooling channel 600 transversely penetrates the cooling liquid inlet 600-a and the cooling liquid outlet 600-b. The temperature and flow rate of the cooling liquid are controlled by an external system to achieve the effect of balancing the temperature of the electrostatic chuck body.

[0026] After the wafer W is mounted on the dielectric 100, the positive and negative electrode groups 200-1 and 200-2 apply direct high voltage to the wafer W, which is adsorbed on the edge gas sealing ring 400 and the micro-convex platform 400-1 placed on the dielectric 100. At this time, the inactive gas atmosphere space is in a sealed state, and the external gas source A inputs inactive gas through the heat dissipation air channel 500, and fills the inactive gas atmosphere space with an appropriate amount of inactive gas through the upper and lower through-gas channel holes 500-a, 500-b, and 500-c, which can enhance the temperature control of the wafer W.

[0027] Example 2 This embodiment will further illustrate the method for manufacturing the dielectric 100. First, KH550@alumina powder is prepared by a known surface modification method such as a liquid phase modification method, or purchased commercially. Next, an appropriate amount of KH550@alumina powder is added to a polyimide solution, and an organic binder or sintering aid that can improve formability is appropriately added, and the stock solution Y is cast (calendered) and sintered into a thin sheet F having an ideal thermal conductivity, bulk resistivity, and surface morphology using a known vacuum thermoforming machine.

[0028] Furthermore, electrode patterns are manufactured on the molded sheet by known methods such as screen printing, bonding, exposure, etching, etc. After completing the surface treatment such as plasma, solution A is placed in an unmarked vacuum mold, and an appropriate amount of stock solution Y is injected again, and a second vacuum thermoforming machine casting (calendering) sintering is performed to prepare a thin sheet F1.

[0029] Continuing with the above-mentioned embodiment, the surface of the thin sheet F1 that contacts the wafer W is flattened and mirror-polished by grinding to obtain an ideal structure.

[0030] Next, an annular edge gas sealing ring 400 and a plurality of micro bosses 400 - 1 disposed inside the edge gas sealing ring are prepared.

[0031] In this embodiment, screen printing is used as an example. A screen printing template without a specific pattern structure is used to print the stock solution Y onto the surface treated thin sheet F1, and the annular edge gas sealing ring and the micro-boss pattern structure are consistent, and vacuum heat sintering is performed again to prepare a thin sheet F2 with an annular edge gas sealing ring and a micro-boss pattern structure.

[0032] Through grinding, the surface of the thin sheet F2 that contacts the wafer W is flattened and mirror-polished to obtain an ideal structure. The surface roughness of the annular edge gas sealing ring and the micro-convex platform is ≤Ra: 0.1μm and the flatness is ≤5μm.

[0033] In this embodiment, the electrostatic chuck is used for a long time in a corrosive gas vacuum atmosphere without the occurrence of suspended particles and metal elements precipitating to contaminate the back of the wafer, and has good cooling and temperature control performance for the wafer. Example 3

[0034] In this embodiment, the polymer preferably has polyimide as the main phase, which has better low outgassing performance in vacuum atmospheres such as halogen-based gases than alumina and aluminum nitride ceramic materials. Even if used for a long time in a corrosive gas vacuum atmosphere, it is not easy for suspended particles and metal elements to precipitate and contaminate the back of the chip. In addition, the electrostatic chuck dielectric layer, edge gas sealing ring and micro-bump can be formed by materials with higher cleanliness performance different from the above-mentioned ceramic materials. Therefore, by realizing the edge gas sealing ring and micro-bump structure in the polymer dielectric layer, an inactive gas atmosphere space composed of the edge gas sealing ring and the chip is formed, and the heat conduction in the plane direction of the electrostatic chuck can further improve the temperature uniformity and cleanliness on the chip.

[0035] The preferred embodiments of the present invention have been described in detail above, but it should be understood that after reading the above teachings of the present invention, the technology is not limited to the description in the specification and the embodiment, so all equivalent changes or modifications made according to the structure, features, and preparation methods within the scope of the present invention should be included in the scope of the present invention. Any semiconductor process that requires the wafer to be fixed in place, such as photolithography, etching, conventional ion implantation, physical vapor deposition, chemical vapor deposition, bonding, nanoimprinting, etc. can use this component. In addition, any application that requires this electrostatic chuck assembly can incorporate the polymer as dielectric material and the polymer material as micro-relief structure disclosed in this specification.

[0036] 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 an electrostatic chuck, characterized in that: The electrostatic chuck includes an electrostatic chuck body, a dielectric, an electrode group, and a metal base; The manufacturing steps are as follows: Step 1: The metal base is made of several pieces of aluminum alloy and subjected to multiple machining processes, and then assisted by one or more processes such as brazing, friction stir welding, and ion beam welding, so as to complete the inactive gas channel and coolant channel inside this layer; Step 2: On the main body of the electrostatic chuck, the gas channel runs through three gas channel holes from top to bottom and communicates with the wafer and the edge gas sealing ring; an inactive gas source is installed to introduce the inactive gas into the unmarked inactive gas atmosphere interval formed by the wafer and the edge gas sealing ring through the gas channel provided on the metal base, and the flow rate and flow velocity of the inactive gas are controlled to achieve the effect of balancing the wafer temperature; Step 3: On the electrostatic chuck body, a cooling channel is provided to horizontally penetrate the coolant inlet and the coolant outlet; the temperature and flow rate of the coolant are controlled to achieve the effect of balancing the temperature of the electrostatic chuck body; Step 4: After the chip is mounted on the dielectric, the positive and negative electrode groups apply direct high voltage and the chip is adsorbed on the edge gas sealing ring and micro-protrusion placed on the dielectric; at this time, the inactive gas atmosphere space is in a sealed state, and the external gas source inputs inactive gas through the heat dissipation air duct, and the three gas channel holes that pass through the top and bottom are filled with an appropriate amount of inactive gas into the inactive gas atmosphere space, which can enhance the temperature control of the chip.

2. The method for manufacturing an electrostatic chuck according to claim 1, characterized in that: The dielectric uses an insulating material with a relatively high dielectric constant or a semiconductor material mixed with an insulator and a metal oxide, wherein the internal electrode group material uses aluminum, copper or other conductive materials, and the metal base is made of aluminum alloy 6061-T651.

3. The method for manufacturing an electrostatic chuck according to claim 1, characterized in that: The steps for making dielectrics are as follows: S1, using the surface modification treatment method to prepare KH550 @ alumina powder, then, an appropriate amount of KH550 @ alumina powder is added to the polyimide solution, and an organic binder or sintering aid is appropriately added to improve the formability, and the stock solution Y is cast / calendered and sintered into a thin sheet F using a known vacuum thermoforming machine; S2, manufacturing electrode patterns on the formed sheet by screen printing, bonding, exposure or etching; after completing the plasma surface treatment, placing solution A in an unmarked vacuum mold, and injecting an appropriate amount of stock solution Y again, and performing secondary vacuum thermoforming machine casting / calendering sintering to prepare thin sheet F1; S3, through grinding, the surface of the thin sheet F1 that contacts the wafer W is flattened and mirror-polished to obtain the desired structure; S4, preparation of an annular edge gas sealing ring and a plurality of micro bosses 400-1 disposed inside the edge gas sealing ring; S5, through grinding, the surface of the thin sheet F2 that contacts the wafer W is flattened and mirror-polished to obtain an ideal structure; the surface roughness of the annular edge gas sealing ring and the micro-protrusion is ≤Ra: 0.1μm and the flatness is ≤5μm.

4. The method for manufacturing an electrostatic chuck according to claim 3, characterized in that: In step S3, an electrode pattern is manufactured on a formed sheet by silk screen printing, and a silk screen template without a specific pattern structure is used to print the stock solution Y onto the surface treated thin sheet F1, and the annular edge gas sealing ring and the micro-boss pattern structure are consistent, and vacuum heat sintering is performed again to prepare a thin sheet F2 having an annular edge gas sealing ring and a micro-boss pattern structure.

5. The method for manufacturing an electrostatic chuck according to claim 1, characterized in that: The chip is set on the edge gas sealing ring and micro-boss on the dielectric of the electrostatic chuck, and both are made of polyimide; the dielectric is made of polyimide material, which may include an annular edge gas sealing ring in contact with the circumferential edge surface of the back side of the chip and a plurality of micro-bosses placed inside the edge gas sealing ring, forming a relatively closed inactive gas atmosphere space; the edge gas sealing ring is slightly higher than the micro-boss and is in contact with the chip at the same time, and jointly supports the chip, and the presence of the micro-boss maximizes the area of ​​the inactive gas atmosphere space, that is, increases the contact area between the inactive gas and the chip.

6. The method for manufacturing an electrostatic chuck according to claim 1, characterized in that: A positive and negative electrode group is arranged inside the dielectric, and a DC high voltage is applied to both ends of the positive and negative electrode group by an external high-voltage DC power supply.

7. The method for manufacturing an electrostatic chuck according to claim 1, characterized in that: Add metal oxides with similar thermal expansion coefficients during the preparation of dielectrics; including alumina modified nanopowders, aluminum nitride modified nanopowders or diamond-like carbon modified nanopowders, wherein the content of alumina is not higher than 5%, the thermal conductivity is not lower than 0.4W / m·K, and the surface resistivity is not lower than 10 13 ohm / sq.

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