Method for manufacturing an electrostatic chuck

Abstract

The application discloses a manufacturing method of an electrostatic chuck, which comprises an electrostatic chuck body, a dielectric, an electrode group and a metal base. The manufacturing steps are as follows: Step one: the metal base realizes the completion of the internal non-reactive gas channel and the cooling liquid channel; Step two: on the electrostatic chuck body, the gas channel penetrates three gas channel holes from top to bottom, and communicates with the wafer and the edge gas sealing ring; Step three: on the electrostatic chuck body, the cooling channel penetrates the cooling liquid input port and the cooling liquid output port laterally; the temperature and the flow rate of the cooling liquid are controlled by an external system to balance the temperature of the electrostatic chuck body; Step four: after the wafer is carried on the dielectric, the positive and negative electrode groups apply direct high pressure, and the wafer is adsorbed on the edge gas sealing ring and the micro boss arranged on the dielectric. The application has the advantages that a non-reactive gas atmosphere space composed of the external edge gas sealing ring of the high-clean electrostatic chuck and the wafer is realized.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of semiconductor and flat panel display manufacturing, and particularly to a manufacturing method of an electrostatic chuck. BACKGROUND

[0002] In order to obtain desired wafer pattern structure in semiconductor manufacturing process, ion implantation and etching, PVD and CVD film forming and other treatments are performed on the wafer. In the vacuum processing device for performing these treatments, an electrostatic chuck is installed to fix the wafer in the processing chamber in vacuum atmosphere. In the known document, an electrode is embedded in the main dielectric of the electrostatic chuck, and the clamping force on the wafer is generated by applying high voltage from outside.

[0003] It is known that during the treatment process in the above-mentioned vacuum processing device, temperature deviation phenomenon occurs, and in more advanced processes, the wafer is sometimes controlled in a specified temperature range. In this case, if the temperature is lower than the set value, a resistive heating sheet is provided in the electrostatic chuck to provide the necessary heat; if cooling is required, a non-active gas is supplied to the internal space formed by the wafer and the clamping surface of the electrostatic chuck through the gas channel provided in the main body of the electrostatic chuck. The non-active gas atmosphere space composed of the gas sealing ring at the outer edge of the electrostatic chuck and the wafer can accelerate the heat conduction from the electrostatic chuck to the wafer, thereby providing stable and accurate temperature control for the wafer.

[0004] In addition, in order to realize the non-active gas atmosphere space composed of the gas sealing ring at the outer edge of the electrostatic chuck and the wafer, high-impedance ceramic sheets such as aluminum nitride or silicon nitride are usually used as the dielectric layer of the electrostatic chuck, and the gas sealing ring is formed on the ceramic sheet by a known method, and a number of micro-boss structures are used to reduce the contact between the wafer and the ceramic sheet. However, in order to maintain the stable clamping effect of the wafer, the gas sealing ring and the micro-boss need to be processed to the desired surface finish without increasing the clamping voltage.

[0005] However, after the high-temperature co-fired aluminum nitride or aluminum nitride ceramic is planar polished or ground, and the application of high voltage to the electrostatic chuck is stopped, the residual charge makes the wafer unable to be quickly and stably released. The ceramic surface that has been planar polished or ground will be physically and chemically eroded after repeated clamping and releasing in the vacuum processing device, and there will be aluminum nitride or aluminum nitride particles precipitated on the surface, which will be in an electrically suspended state, making it difficult to quickly release the residual polarization charge between the ceramic surface and the wafer. In addition, these suspended particles and metal elements will adhere to the back of the wafer, causing wafer contamination and irreversible damage.

[0006] In addition, using high impedance, corrosion resistant, low outgassing material such as polyimide as a representative polymer as the dielectric layer of the electrostatic chuck can eliminate the contamination of the wafer back by the suspended ions and elements on the surface of the dielectric layer, but if the non-active gas atmosphere space formed by the electrostatic chuck outer edge gas sealing ring and the wafer is to be realized, it is limited by material processing and performance constraints, and the heat conduction performance of the electrostatic chuck from the drawing to the wafer cannot be accelerated, and the wafer cannot provide sufficient stable temperature regulation function. SUMMARY

[0007] In order to solve the defects and deficiencies existing in the prior art, the present application provides a manufacturing method of an electrostatic chuck, which realizes the edge gas sealing ring and the micro-boss structure by the polymer dielectric layer, forms the non-active gas atmosphere space formed by the edge gas sealing ring and the wafer, and further improves the wafer temperature uniformity and cleanliness.

[0008] The present application provides the following technical scheme: a manufacturing method of 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:

[0009] Step one: the metal base is made of several pieces of aluminum alloy and is processed by multiple mechanical processes, and is assisted by one or more processes of brazing process, friction stir welding, and ion beam welding to realize the completion of the internal non-active gas channel and the cooling liquid channel;

[0010] Step two: three gas channel holes are vertically through the gas channel on the electrostatic chuck body, and are communicated with the wafer and the edge gas sealing ring; a non-active gas source is installed to guide the non-active gas into the non-active gas atmosphere interval formed by the wafer and the edge gas sealing ring through the gas channel of the metal base, and the flow and flow rate of the non-active gas are controlled by an external system to balance the temperature of the wafer;

[0011] Step three: the cooling channel is transversely through the cooling input port and the cooling liquid output port on the electrostatic chuck body; the temperature and flow rate of the cooling liquid are controlled by an external system to balance the temperature of the electrostatic chuck body;

[0012] Step four: after the wafer is carried on the dielectric, the positive and negative electrode groups are directly applied with high voltage, and the wafer is adsorbed on the edge gas sealing ring and the micro-boss on the dielectric; at this time, the non-active gas atmosphere space is in a sealed state, the non-active gas is input by the heat dissipation gas channel from the external gas source, and the appropriate amount of non-active gas is filled into the non-active gas atmosphere space through the three gas channel holes vertically through, which can strengthen the temperature regulation of the wafer.

[0013] Preferably, the dielectric uses insulating materials or semiconducting materials mixed with metal oxides with relatively high dielectric constant, the internal electrode group material uses aluminum, copper or other conductive materials, and the metal base is made of aluminum alloy 6061-T651.

[0014] Preferably, the manufacturing steps of the dielectric are as follows:

[0015] S1, prepare KH550@alumina powder by surface treatment modification, then add a proper amount of KH550@alumina powder into polyimide solution, and add a proper amount of organic binder or sintering aid capable of improving formability, and use a known vacuum hot forming machine to flow / cast and sinter the stock solution Y into a thin sheet F with ideal thermal conductivity, volume resistivity and surface morphology;

[0016] S2, manufacture electrode patterns on the formed sheet by silk printing, bonding, exposure or etching; after completing plasma surface treatment, place solution A into an unmarked vacuum mold, and again inject a proper amount of stock solution Y to perform secondary vacuum hot forming machine flow / cast and sinter to prepare a thin sheet F1;

[0017] S3, by grinding processing, the contact side of the thin sheet F1 surface with the wafer W is planarized and mirror polished to obtain an ideal structure;

[0018] S4, preparation of an annular edge gas sealing ring and a plurality of micro-bosses 400-1 arranged inside the edge gas sealing ring;

[0019] S5, by grinding processing, the contact side of the thin sheet F2 surface with the wafer W is planarized and mirror polished to obtain an ideal structure; the surface roughness of the annular edge gas sealing ring and the micro-bosses is ≤Ra: 0.1 μm and the flatness is ≤5 μm.

[0020] Preferably, in the step S3, the electrode patterns are manufactured on the formed sheet by silk printing, a silk 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-bosses have the same pattern structure, and vacuum hot sintering is performed again to prepare a thin sheet F2 with the annular edge gas sealing ring and the micro-bosses pattern structure.

[0021] Preferably, the electrostatic chuck is used in a corrosive gas vacuum atmosphere for a long time, and is not easy to cause contamination of the wafer back by precipitation of suspended particles and metal elements, and has good cooling and temperature control performance for the wafer.

[0022] Preferably, the wafer is arranged on the edge gas sealing ring and micro-tubercle above the electrostatic chuck dielectric, and both are made of polyimide material; the dielectric is made of polyimide material, which can include an annular edge gas sealing ring in contact with the circumferential edge surface of the wafer back surface and a plurality of micro-tubercles arranged inside the edge gas sealing ring, forming a relatively closed non-active gas atmosphere space; the edge gas sealing ring is slightly higher than the micro-tubercle and is in contact with the wafer, supporting the wafer together, and the presence of the micro-tubercle maximizes the area of the non-active gas atmosphere space, i.e. increases the contact area of the non-active gas with the wafer.

[0023] Preferably, a positive and negative electrode group is arranged inside the dielectric, and a high-voltage direct-current power supply is arranged outside to apply direct-current high voltage to both ends of the positive and negative electrode group.

[0024] Preferably, a metal oxide with similar thermal expansion coefficient is added during the preparation of the dielectric; the metal oxide includes modified nano-micropowder of aluminum oxide, modified nano-micropowder of aluminum nitride, or modified nano-micropowder of diamond-like substance, wherein the content of the aluminum oxide is not higher than 5%, the thermal conductivity coefficient is not lower than 0.4 W / m·K, and the surface resistivity is not lower than 10 ohm / sq. 13

[0025] The present application forms the non-active gas atmosphere space composed of the edge gas sealing ring and the wafer by realizing the edge gas sealing ring and micro-tubercle structure on the polymer dielectric layer, and further improves the temperature uniformity and cleanliness on the wafer by improving the heat conduction in the plane direction of the electrostatic chuck, and has the non-active gas atmosphere space composed of the edge gas sealing ring and the wafer outside the high-cleanliness electrostatic chuck. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The cross-sectional schematic diagram of the device for the manufacturing method of the present application is shown;

[0027] Figure 2 The plane schematic of the local enlargement of the present application is shown to explain the manufacturing process;

[0028] In the figure, W: wafer, A: non-active gas source, P: high-voltage direct-current 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-tubercle, 400-1b: micro-tubercle; 400-1c: micro-tubercle; 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 input; 600b: cooling liquid output. DETAILED DESCRIPTION

[0029] ​The application will be further described in detail by the following examples and drawings, the raw materials used in the examples are commercially available or prepared by conventional methods. Example 1

[0030] The present embodiment provides a manufacturing method of an electrostatic chuck dielectric layer, edge gas sealing ring and micro-boss, which realizes a high-clean electrostatic chuck outer edge gas sealing ring and wafer composed of a non-active gas atmosphere space.

[0031] The electrostatic chuck main functional components in the present embodiment include: dielectric 100, electrode group 200, metal base 300. To manufacture the dielectric 100, generally use insulating materials or semiconducting materials mixed with metal oxides with relatively high dielectric constant, and the present embodiment preferably uses polyimide material. Among them, the internal electrode group 200 material is preferably selected from such as aluminum (Al), copper (Cu) and other conductive materials, and the metal base 300 is manufactured by selecting aluminum alloy 6061-T651.

[0032] As shown in Figure 1 , the wafer W is arranged on the electrostatic chuck dielectric 100, the edge gas sealing ring 400 and the micro-boss 400-1, and both are made of polyimide material. As shown in Figure 2 , the dielectric 100 is made of, for example, polyimide material, which can include an annular edge gas sealing ring 400 in contact with the circumferential edge surface of the back of the wafer W and a plurality of micro-bosses 400-1 arranged inside the edge gas sealing ring, forming a relatively closed non-active gas atmosphere space. The edge gas sealing ring 400 is slightly higher than the micro-boss 400-1, and in actual cases, the edge gas sealing ring 400 is slightly higher than the micro-boss 400-1 while in contact with the wafer W, and together supports the wafer W. In addition, the presence of the micro-boss 400-1 maximizes the area of the non-active gas atmosphere space, i.e. increases the contact area of the non-active gas with the wafer W.

[0033] The positive and negative electrode groups 200-1, 200-2 are arranged inside the dielectric 100, and a high-voltage direct-current power supply P is used to apply a direct-current high voltage to both ends of the positive and negative electrode groups.

[0034] In order to improve the heat conduction performance of the electrostatic chuck, a commonly known preparation method is used to add metal oxides with similar thermal expansion coefficients during the preparation of the dielectric 100. By adding, for example, modified nanometer powder of aluminum oxide, modified nanometer powder of aluminum nitride or modified nanometer powder of diamond-like, among which the content of aluminum oxide is not higher than 5%, and the thermal conductivity coefficient is not less than 0.4 W / m·K, and the surface resistivity must not be less than 10 13 ohm / sq.

[0035] The metal base 300 is primarily constructed of a high-strength aluminum alloy (6061-T651). Several aluminum alloy pieces undergo multiple machining processes, supplemented by brazing, friction stir welding, and ion beam welding, to create the inert gas channels 500 and coolant channels 600 within this layer. On the electrostatic chuck body, the gas channels 500 extend vertically through gas channel holes 500-a, 500-b, and 500-c, connecting to the wafer W and the edge gas seal ring 400. An inert gas source A, equipped with an inert gas source, introduces inert gas through the gas channels 500 provided within the metal base 300 into the unlabeled inert gas atmosphere space formed between the wafer W and the edge gas seal ring 400. The inert gas flow rate and velocity are controlled by an external system to balance the temperature of the wafer W.

[0036] Continuing from the above, a cooling channel 600 runs transversely through the cooling liquid inlet 600-a and the cooling liquid outlet 600-b on the electrostatic chuck body. 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.

[0037] After wafer W is mounted on dielectric 100, a direct high voltage is applied to the positive and negative electrode groups 200-1 and 200-2, causing wafer W to be attracted to the edge gas seal ring 400 and micro-bump 400-1 of dielectric 100. At this point, the inert gas atmosphere is sealed. External gas source A introduces inert gas through heat dissipation duct 500, and an appropriate amount of inert gas is filled into the inert gas atmosphere through vertical through-holes 500-a, 500-b, and 500-c, enhancing temperature control of wafer W.

[0038] Example 2

[0039] This embodiment will further illustrate the method for manufacturing the dielectric 100.

[0040] First, KH550@alumina powder is prepared using a known surface modification method, such as a liquid-phase modification process, or purchased commercially. Next, an appropriate amount of KH550@alumina powder is added to a polyimide solution, along with an organic binder or sintering aid to enhance formability. The solution Y is then tape-cast (calendered) and sintered using a known vacuum thermoforming machine to form a thin sheet F with the desired thermal conductivity, bulk resistivity, and surface morphology.

[0041] Furthermore, electrode patterns are fabricated on the formed sheet through known methods such as screen printing, bonding, exposure, and etching. After surface treatment, such as plasma treatment, Solution A is placed in an unlabeled vacuum mold and refilled with an appropriate amount of Solution Y. A secondary vacuum thermoforming process, followed by casting (calendering) and sintering, is performed to produce a thin sheet F1.

[0042] In the above embodiment, the surface of the wafer W is polished to a desired structure by grinding and polishing the surface of the sheet F1 that contacts the wafer W.

[0043] Next, the preparation of the annular edge gas seal ring 400 and the plurality of micro-bumps 400-1 inside the edge gas seal ring.

[0044] In this embodiment, screen printing is used as an example. The original solution Y is printed onto the surface-treated sheet F1 using a screen printing template without a specific pattern structure, and the annular edge gas seal ring and the micro-bump pattern structure are consistent. Vacuum hot sintering is performed again to prepare a sheet F2 with an annular edge gas seal ring and a micro-bump pattern structure.

[0045] The surface of the wafer W is polished to a desired structure by grinding and polishing the surface of the sheet F2 that contacts the wafer W. The surface roughness of the annular edge gas seal ring and the micro-bump is ≤ Ra: 0.1 μm, and the flatness is ≤ 5 μm.

[0046] In this embodiment, the electrostatic chuck is used in a corrosive gas vacuum atmosphere for a long time, and is not prone to contamination of the wafer back by suspended particles and the precipitation of metal elements. It also has good cooling and temperature control performance for the wafer. Embodiment 3

[0047] In this embodiment, the polymer is preferably a polyimide as the main phase. Compared with alumina and aluminum nitride ceramic materials, it has better low outgassing performance in a vacuum atmosphere such as a halogen-based gas. Even if it is used in a corrosive gas vacuum atmosphere for a long time, it is not prone to contamination of the wafer back by suspended particles and the precipitation of metal elements. Furthermore, the electrostatic chuck dielectric layer, the edge gas seal ring, and the micro-bump can be formed of a material with higher cleanliness than the above-mentioned ceramic materials. Thus, by realizing the edge gas seal ring and the micro-bump structure in the polymer dielectric layer, forming a non-reactive gas atmosphere space composed of the edge gas seal ring and the wafer, and improving the thermal conductivity of the electrostatic chuck in the plane direction, the temperature uniformity and cleanliness of the wafer can be further improved.

[0048] While the preferred embodiments of the application have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the method and materials can be made by those skilled in the art without departing from the true spirit and scope of the application. Any semiconductor process that requires a wafer to be held in place, such as photolithography, etching, conventional ion implantation, physical vapor deposition, chemical vapor deposition, bonding, nanoimprint, etc. can use this component. In addition, any application that requires such an electrostatic chuck assembly can incorporate the polymer as the dielectric material and the polymer material as the microrelief structure disclosed in this specification.

[0049] While the application has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, since the scope of the application is indicated by the appended claims, along with their equivalent scope in the art.

Claims

1. A method for manufacturing an electrostatic chuck, characterized in that: The electrostatic chuck includes a dielectric, an electrode set, and a metal base; The manufacturing steps are as follows: Step 1: The metal base is made of several pieces of aluminum alloy and undergoes multiple machining processes. Then, it is assisted by one or more processes such as brazing, friction stir welding, and ion beam welding to complete the inert gas channel and coolant channel inside the metal base. Step 2: On the electrostatic chuck, a gas channel runs through three gas channel holes, communicating with the wafer and the edge gas seal ring. An inert gas source is installed to introduce inert gas into the inert gas atmosphere formed by the wafer and the edge gas seal ring through the gas channel provided on the metal base. The flow rate and flow velocity of the inert gas are controlled to achieve the effect of balancing the wafer temperature. Step 3: On the electrostatic chuck, a cooling channel is formed to extend transversely through the coolant inlet and the coolant outlet; the temperature and flow rate of the coolant are controlled to achieve a balanced temperature of the electrostatic chuck; Step 4: After the wafer is mounted on the dielectric, a direct high voltage is applied to the positive and negative electrode groups, causing the wafer to be adsorbed onto the edge gas sealing ring and micro-protrusions placed on the dielectric. At this point, the inert gas atmosphere is sealed, and an external gas source inputs inert gas through the inert gas channel. The inert gas is then filled into the inert gas atmosphere through three gas channel holes that run vertically through the inert gas channel, thereby enhancing temperature control of the wafer. The manufacturing steps of the dielectric are as follows: S1, using surface modification treatment method to prepare KH550 @ alumina powder, then, the KH550 @ alumina powder is added to the polyimide solution, and an organic binder or sintering aid is added to improve the formability, the use of a vacuum thermoforming machine to cast or calender the solution Y sintered into a thin sheet F; S2, thin sheet F after completion of plasma surface treatment, the polyimide solution is placed in a vacuum mold, and again injected into the stock solution Y, a secondary vacuum thermoforming machine casting or calendering sintering to prepare a thin sheet F1; S3, by 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-protrusions disposed inside the edge gas sealing ring; S5, manufacturing an electrode pattern on the thin sheet F1 by screen printing, using a screen printing template with a pattern structure, printing the stock solution Y onto the surface-treated thin sheet F1, and performing vacuum heat sintering to prepare a thin sheet F2 having an annular edge gas sealing ring pattern structure and a micro-convex pattern structure; Through grinding, the surface of the thin sheet F2 in contact with the wafer W is flattened and mirror-polished to obtain an ideal structure; the surface roughness Ra of the annular edge gas sealing ring and the micro-bumps is ≤ 0.1 μm and the flatness is ≤ 5 μm; the dielectric includes an annular edge gas sealing ring in contact with the circumferential edge surface of the wafer back side and a number of micro-bumps placed inside the edge gas sealing ring, forming a relatively closed inert gas atmosphere space; the edge gas sealing ring is slightly higher than the micro-bumps and contacts the wafer to jointly support the wafer. The presence of the micro-bumps maximizes the area of ​​the inert gas atmosphere space, that is, increases the contact area between the inert gas and the wafer; Add modified nanopowders with similar thermal expansion coefficients during the dielectric preparation process; The modified nanopowder comprises alumina modified nanopowder and optionally one or more of aluminum nitride modified nanopowder and diamond-like carbon modified nanopowder, wherein the content of aluminum oxide in the modified nanopowder is not higher than 5%, and the thermal conductivity of the prepared dielectric is not lower than 0.4 W / m·K, and the surface resistivity is not lower than 10 13 ohm / sq.

2. The method for manufacturing an electrostatic chuck according to claim 1, wherein: The dielectric's internal electrode group material is made of aluminum or copper, and the metal base is made of aluminum alloy 6061-T651.

3. The method for manufacturing an electrostatic chuck according to claim 1, wherein: 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.

Images