Method for repairing back helium runner type electrostatic chuck

Abstract

The invention relates to the technical field of integrated circuit equipment, in particular to a method for repairing a back helium flow channel type electrostatic chuck. According to the method, an insulating layer of the electrostatic chuck and an electrostatic electrode in the electrostatic chuck are removed by adopting physical sand blasting and chemical etching methods, and then the electrostatic chuck is manufactured through a plasma spraying process of aluminum oxide or aluminum nitride ceramic powder in cooperation with the mask effect of I nvar steel. And an insulating layer-electrostatic electrode-insulating layer sandwich structure with the same thickness is formed on the surface of the Al substrate structure, and finally, the electrostatic chuck is ensured to meet the regeneration use effect through the processes of hole sealing treatment, precise cleaning, vacuum drying and the like.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuit devices, and more specifically, to a method for repairing a back-helium flow channel type electrostatic chuck. Background Art

[0002] In integrated circuit production equipment, wafers or glass panels need to be placed flat on the tray to avoid tilting during ion bombardment. At the same time, good heat dissipation needs to be maintained to avoid adverse effects of temperature changes on etching rate. Based on this, the electrostatic chuck was developed, which plays an important role in etching quality and stability.

[0003] The structure of the electrostatic chuck includes an insulating layer, helium holes, back helium channels, electrostatic electrodes, circulating cooling water and heating electrodes. The insulating layer, ejector pins, helium holes and back helium channels are located on the surface of the electrostatic chuck or in contact with the surface. During the long-term production process, this part is in contact with the materials or gases in the process chamber, producing SiF4, SiCl4 and other compounds that are contaminated on the surface of the electrostatic chuck, resulting in a reduction in yield or changes in performance.

[0004] Therefore, it is necessary to clean the electrostatic chuck regularly and inspect and repair the insulating layer, helium holes, back helium flow channels, electrostatic electrodes and other areas to ensure the stability of dielectric properties and the effect of electrostatic adsorption during the integrated circuit production process. Summary of the invention

[0005] The object of the present invention is to provide a method for repairing a back-helium flow channel type electrostatic chuck, which is used to ensure the stability of the dielectric properties and the electrostatic adsorption effect of the electrostatic chuck during the production of integrated circuits.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for repairing a back-helium flow channel type electrostatic chuck comprises the following steps:

[0008] (1) Using tape to protect the smooth surface areas on the sides and bottom of the electrostatic chuck, and then measuring the surface structure size of the electrostatic chuck and making a mask based on the surface structure size;

[0009] (2) Immerse the electrostatic chuck with the insulation surface facing downward in IPA solvent for 8-12 hours to loosen the surface structure of the electrostatic chuck, polish and remove part of the insulation layer at the bottom of the electrostatic chuck, and then rinse the electrostatic chuck;

[0010] (3) placing the electrostatic chuck in an ultrasonic tank for ultrasonic cleaning, and after drying, protecting the helium holes on the polished surface of the electrostatic chuck with a silicone plug, and then sandblasting the polished surface to remove the remaining insulating layer and expose the Al substrate;

[0011] (4) Assembling the mask plate to the surface of the electrostatic chuck, and sequentially spraying an aluminum oxide or aluminum nitride insulating layer and a tungsten electrostatic electrode layer of a required thickness on the surface of the electrostatic chuck by plasma spraying;

[0012] (5) forming a back-helium channel of a bump structure on the surface of the insulating layer by mechanical processing, and performing structural and texture modification;

[0013] (6) The electrostatic chuck is placed in an ultrasonic tank for ultrasonic cleaning. After drying, the flatness and insulation performance are tested. After passing the test, vacuum dust-free packaging is performed.

[0014] The conventional method of removing dielectric materials is mechanical processing and physical stripping. The present invention adopts chemical mechanical grinding for stripping, which has higher precision control and lower damage to the electrostatic chuck.

[0015] Preferably, the mask is made of Invar steel.

[0016] The traditional material for making masks is stainless steel, with a thermal expansion coefficient of 16.8x10 -6 K -1 The thermal expansion coefficient of the Invar steel used in the present invention is 1.6x10 -6 K -1 In a sudden cooling and heating environment, the precision control of the mask made of Invar steel is improved by 10 times compared with the traditional process.

[0017] Preferably, in step (2), a 600-800# diamond grinding disc is used to grind and polish away a portion of the insulating layer of the electrostatic chuck.

[0018] Preferably, deionized water is added during the grinding and polishing process to prevent poor grinding or structural damage caused by temperature rise during the grinding and polishing process.

[0019] Preferably, in step (2), a steam gun with a pressure of 0.5-0.7 MPa is used to rinse the electrostatic chuck after grinding and polishing to remove debris, particles and impurities generated during the grinding and polishing process.

[0020] Preferably, in step (3), the rinsed electrostatic chuck is placed in a vacuum chamber with an energy density of 4-8 W / i nch. 2 Ultrasonic cleaning is carried out in an ultrasonic tank, and the cleaning time is controlled to be 15-20 minutes.

[0021] Preferably, in step (3), the electrostatic chuck that has been ultrasonically cleaned is placed in an oven set at a temperature of 120±10° C. and baked for 2 hours to remove residual moisture on the surface of the electrostatic chuck.

[0022] Preferably, in step (3), a silicone plug is used to protect the helium holes on the polished surface of the electrostatic chuck, and then the polished surface is sandblasted with 46# alumina sand at a sandblasting pressure of 0.3-0.4 MPa, and the roughness Ra value is controlled to 3-5 um to ensure that the insulating layer can form a good bonding force with the Al substrate in the electrostatic chuck during the plasma spraying process.

[0023] Preferably, in step (6), the electrostatic chuck after the texture modification treatment is placed in a deionized water ultrasonic tank for ultrasonic washing, the working environment is a Class 1000 or Class 100 clean room, and the ultrasonic energy density is 4-8w / inch. 2 , the deionized water temperature is controlled at 25-28℃, and the time is controlled at 25-30min.

[0024] Preferably, in step (6), the planarity is controlled to be no greater than 10 um and the insulation resistance is controlled to be greater than 50 MΩ.

[0025] In summary, the present application has the following beneficial effects: the present invention adopts a chemical mechanical polishing method to remove dielectric materials, which has higher precision control and lower damage to the electrostatic chuck; in addition, the mask made of Invar steel can achieve higher precision control, ensuring the stability of the dielectric properties of the electrostatic chuck and the electrostatic adsorption effect during the integrated circuit production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view of an electrostatic chuck;

[0027] Figure 2 This is a partial enlarged view of the insulating layer in the electrostatic chuck.

[0028] In the figure: 1. Insulating layer; 2. Helium hole; 3. Back helium channel; 31. Bump; 4. Electrostatic electrode; 5. Circulating cooling water; 6. Heating electrode; 7. Al substrate. DETAILED DESCRIPTION

[0029] The implementation of the present invention is described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0030] Figure 1 The figure shows a cross-sectional view of a conventional electrostatic chuck, the main structure of which includes an Al substrate 7 and an insulating layer 1, as well as a heating electrode 6, a cooling water circulation pipeline 5, a helium hole 2 and other structures embedded in the Al substrate 7, and an electrostatic electrode 4 embedded in the insulating layer 1. The bottom of the insulating layer 1 is a back helium channel 3, which is formed by a plurality of bumps 31.

[0031] Figure 2The figure shows a cross-sectional view of the structure of the insulating layer of the electrostatic chuck. Taking the Al2O3 insulating layer as an example, the key part of the main body is the Al2O3:W:Al2O3 (450um:50um:450um) structure at the top, which is the most important part of the electrostatic adsorption effect.

[0032] Example 1

[0033] The present invention provides a method for repairing a back-helium flow channel type electrostatic chuck, which uses physical sandblasting and chemical etching methods to remove the ESC (electrostatic chuck) insulation layer and the electrostatic electrode (tungsten electrode) inside it, and then forms an insulation layer-electrostatic electrode-insulation layer sandwich structure of the same thickness on the surface of the Al substrate structure through a plasma spraying process of aluminum oxide or aluminum nitride ceramic powder and a masking effect of Invar steel. Finally, after sealing treatment, precision cleaning, vacuum drying and other processes, the regeneration effect of the ESC is ensured.

[0034] The steps to implement the repair method are as follows:

[0035] (1) Use tape to stick and protect the smooth surface areas on the side and bottom of the electrostatic chuck, then measure the surface structure size of the electrostatic chuck and make a mask plate based on the surface structure size.

[0036] Specifically, according to the specific structural design of the ESC surface, a special wear-resistant protective tape for the smooth surface area is pasted on the smooth surface area of ​​the ESC side and bottom for protection (the ESC surface has smooth areas and rough areas. The smooth area needs to be protected during the operation to avoid damage to it during the operation. The "special wear-resistant protective tape for the smooth surface area" mentioned here refers to the protective tape customized for processing according to the structure of the smooth surface area of ​​the component surface to ensure a better protection effect) to prevent the smooth surface area of ​​the ESC from being damaged or defective due to friction or collision during the repair operation; then a three-coordinate measuring machine is used to detect the change trend of the surface size structure and thickness of the ESC, and the surface structure curve is drawn to design the surface convex point (Emboss) mask structure size, and the mask material is selected as Invar steel with a very low thermal expansion coefficient. It is designed as a hole-like structure according to the structural characteristics of Emboss, and its characteristics are that the convex point position is hollowed out and the non-convex point position is blocked; then a laser cutting method is used to cut out the morphology of the insulating layer and the conductive layer on the Invar steel with a thickness of 1.0 mm to make a mask.

[0037] (2) Immerse the electrostatic chuck with the insulation surface facing downward in IPA solvent for 8-12 hours to loosen the surface structure of the electrostatic chuck, polish and remove part of the insulation layer at the bottom of the electrostatic chuck, and then rinse the electrostatic chuck.

[0038] Specifically, the electrostatic chuck is immersed in IPA (isopropyl alcohol) solvent with the insulation surface facing downward for 10 hours to loosen the surface structure of the electrostatic chuck to improve the stripping efficiency of the insulation layer; then the ESC is fixed on the processing table of the grinding and polishing machine, and the Al2O3 insulation layer structure on the surface of the ESC is polished using a 600# diamond grinding wheel. Deionized water is added during the grinding and polishing process to prevent the temperature from rising during the grinding and polishing process, resulting in poor grinding and polishing or structural damage; the above method is used to remove most of the Al2O3 insulation layer on the surface of the ESC (the depth of this part of the insulation layer is as follows Figure 2 As shown in A in the figure, including tungsten electrostatic electrode), it is used to prevent the Al substrate underneath from being damaged due to over-polishing; then the ESC body parts after polishing are rinsed with a steam gun with a pressure of 0.5-0.7MPa, and the helium hole and the surrounding area of ​​the hole are checked with a bore gauge and an endoscope. Figure 1 The upper surface of the helium hole (empty edge area) is inspected to remove burrs, particles, debris, etc. generated during the grinding and polishing process.

[0039] (3) The electrostatic chuck is placed in an ultrasonic tank for ultrasonic cleaning. After drying, the helium holes on the polished surface of the electrostatic chuck are protected with silicone plugs. The polished surface is then sandblasted to remove the remaining insulating layer and expose the Al substrate.

[0040] Specifically: put the cleaned ESC into a chamber with an energy density of 6±2w / inch 2 The ultrasonic cleaning was carried out in an ultrasonic tank for 15 minutes. The ESC after ultrasonic cleaning was then placed in an oven set at 120±10℃ for 2 hours to remove the residual moisture on the surface of the component. The helium holes on the polished surface of the ESC were then protected with silicone plugs. The polished surface was then sandblasted with 46# alumina sand at a sandblasting pressure of 0.3-0.4MPa to remove the remaining small amount of insulation layer (the depth of which is as follows: Figure 2 As shown in B, it is about 3-20um), and the roughness Ra value is controlled to be 3-5um, which is used to ensure that the insulating layer can form a good bonding force with the Al substrate during the plasma spraying process to avoid the occurrence of defects.

[0041] (4) Assembling the mask plate to the surface of the electrostatic chuck, and using plasma spraying to spray the required thickness of aluminum oxide or aluminum nitride insulating layer and tungsten electrostatic electrode layer on the surface of the electrostatic chuck in sequence.

[0042] Specifically, the mask is assembled to the surface of the ESC, and the aluminum oxide or aluminum nitride insulating layer and the tungsten electrostatic electrode layer sandwich structure of the required thickness are sprayed on the surface of the ESC in sequence by plasma spraying; (When re-manufacturing the insulating layer and the electrostatic electrode layer, due to the difference in structural areas, some positions on the same surface can be sprayed with materials, while others cannot. The purpose of the mask is to cover the areas that cannot be sprayed).

[0043] (5) forming a back-helium channel of a bump structure on the surface of the insulating layer by mechanical processing, and performing related structural and texture modification;

[0044] (6) The electrostatic chuck is placed in an ultrasonic tank for ultrasonic cleaning. After drying, the flatness and insulation performance are tested. After passing the test, vacuum dust-free packaging is performed.

[0045] Specifically, the surface treated ESC is placed in a deionized water ultrasonic tank for ultrasonic washing. The working environment is a Class 1000 or Class 100 clean room. The ultrasonic energy density is 6±2w / inch. 2 , the temperature of deionized water is controlled at 25-28℃, the time is controlled at 25min, and attention is paid to the placement angle of the ESC to avoid the problem of superposition causing the particle size (Part ic le) cleaning effect to be reduced. The surface treated ESC is placed in a vacuum oven for drying. The working environment is a Class 100 clean room, the temperature is set to 120±10℃, and the temperature is kept constant for 4 hours before natural cooling. The baked ESC is tested for flatness and insulation performance. A three-coordinate measuring machine is used to check the flatness, and an insulation resistance meter is used to test the insulation performance. The flatness is controlled within 10um (not more than 10um), and the insulation resistance is greater than 50MΩ. Select packaging materials that meet the requirements of micro-pollution control to vacuum-pack the qualified ESC to prevent the entry of external dust particles or moisture during turnover, transportation, and storage from causing product contamination.

[0046] Comparative Example 1

[0047] A method for repairing a back-helium flow channel type electrostatic chuck, which differs from Example 1 only in that the mask made of Invar steel is replaced with a mask made of stainless steel.

[0048] Comparative Example 2

[0049] A method for repairing a back-helium flow channel type electrostatic chuck, which differs from Example 1 only in that the step of using IPA solvent to wet the bottom insulating surface of the electrostatic chuck is omitted.

[0050] Ten electrostatic chucks repaired by the repair methods described in Example 1, Comparative Example 1 and Comparative Example 2 were selected, and 10 new electrostatic chucks (with a diameter of 6 inches and a thickness of 12.6 mm) were used as a control group to test the flatness, insulation resistance and adsorption force. The adsorption voltage during the adsorption force test was 1000 V, and the adsorption object was a glass plate. The average values ​​of each group were calculated, and the results are shown in Table 1.

[0051] Table 1: Performance data of each group of electrostatic chucks

[0052] Group Flatness(μm) Insulation resistance(MΩ) Adsorption force (N) Example 1 Group 5.7 95.8 13.6 Comparative Example 1 9.2 92.6 10.4 Comparative Example 2 15.6 85.2 8.8 Control group ＜2 102.5 14.3

[0053] By comparing Example 1 and Comparative Example 1, it can be seen that the mask made of Invar steel can achieve higher precision control, ensuring that the repaired electrostatic chuck has a certain degree of improvement in flatness and adsorption. By comparing Example 1 and Comparative Example 2, it can be seen that the present invention uses a chemical mechanical polishing method to remove dielectric materials, which has higher precision control, lower damage to the electrostatic chuck, and significantly improved flatness and adsorption of the repaired electrostatic chuck; by comparing Example 1 and the control group, it can be seen that the repaired electrostatic chuck is slightly lower than a brand new electrostatic chuck in terms of flatness, insulation resistance and adsorption, and can maintain the stability of dielectric properties and the effect of electrostatic adsorption during the production of integrated circuits, meeting the use requirements.

[0054] The above specific embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for repairing a back-helium flow channel type electrostatic chuck, characterized in that: The following steps are involved: (1) Using tape to protect the smooth surface areas on the sides and bottom of the electrostatic chuck, and then measuring the surface structure size of the electrostatic chuck and making a mask based on the surface structure size; (2) Immerse the electrostatic chuck with the insulation surface facing downward in IPA solvent to loosen the surface structure of the electrostatic chuck, polish and remove part of the insulation layer at the bottom of the electrostatic chuck, and then rinse the electrostatic chuck; (3) placing the electrostatic chuck in an ultrasonic tank for ultrasonic cleaning, and after drying, protecting the helium holes on the polished surface of the electrostatic chuck with a silicone plug, and then sandblasting the polished surface to remove the remaining insulating layer and expose the Al substrate; (4) Assembling the mask plate to the surface of the electrostatic chuck, and sequentially spraying an aluminum oxide or aluminum nitride insulating layer and a tungsten electrostatic electrode layer of a required thickness on the surface of the electrostatic chuck by plasma spraying; (5) forming a back-helium channel of a bump structure on the surface of the insulating layer by mechanical processing, and performing structural and texture modification; (6) The electrostatic chuck is placed in an ultrasonic tank for ultrasonic cleaning. After drying, the flatness and insulation performance are tested. After passing the test, vacuum dust-free packaging is performed.

2. The repair method according to claim 1, characterized in that: The material of the mask is Invar steel.

3. The repair method according to claim 1, characterized in that: In step (2), a 600-800# diamond grinding disc is used to polish and remove a portion of the insulating layer of the electrostatic chuck.

4. The repair method according to claim 3, characterized in that: Deionized water is added during the grinding and polishing process to prevent the temperature from rising during the grinding and polishing process, causing poor grinding or structural damage.

5. The repair method according to claim 1, characterized in that: In step (2), a steam gun with a pressure of 0.5-0.7 MPa is used to rinse the electrostatic chuck after grinding and polishing to remove debris, particles and impurities generated during the grinding and polishing process.

6. The repair method according to claim 1, characterized in that: In step (3), the rinsed electrostatic chuck is placed in a vacuum chamber with an energy density of 4-8w / inch. 2 Ultrasonic cleaning is carried out in an ultrasonic tank, and the cleaning time is controlled to be 15-20 minutes.

7. The repair method according to claim 1, characterized in that: In step (3), the electrostatic chuck that has been ultrasonically cleaned is placed in an oven set at a temperature of 120±10° C. and baked for 2 hours to remove residual moisture on the surface of the electrostatic chuck.

8. The repair method according to claim 1, characterized in that: In step (3), a silicone plug is used to protect the helium holes on the polished surface of the electrostatic chuck, and then the polished surface is sandblasted with 46# alumina sand at a sandblasting pressure of 0.3-0.4 MPa, and the roughness Ra value is controlled to 3-5 um to ensure that the insulating layer can form a good bonding force with the Al substrate in the electrostatic chuck during the plasma spraying process.

9. The repair method according to claim 1, characterized in that: In step (6), the textured electrostatic chuck is placed in a deionized water ultrasonic bath for ultrasonic washing in a Class 1000 or Class 100 clean room with an ultrasonic energy density of 4-8 w / inch. 2 , the deionized water temperature is controlled at 25-28℃, and the time is controlled at 25-30min.

10. The repair method according to claim 1, characterized in that: In step (6), the planarity is controlled to be no greater than 10 um and the insulation resistance is controlled to be greater than 50 MΩ.

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