A processing method for the convex microstructure on the regular surface of an electrostatic chuck

Abstract

The present invention discloses a processing method for the convex microstructure on the regular surface of an electrostatic chuck, comprising the following steps: S1, preparing a structured grinding wheel by laser processing; S2, performing multiple ion implantations on the surface of the functional layer of the electrostatic chuck to form multiple modified regions; S3, selectively grinding and removing the multiple modified regions by the structured grinding wheel to form the final convex microstructure on the surface of the ceramic electrostatic chuck functional layer; S4, first performing minimum wear height grinding on the worn electrostatic chuck, grinding the remaining convex microstructures on the surface of the electrostatic chuck functional layer to the same height as the lowest point, and then repeating the above steps S2 and S3 to complete the renovation and repair of the worn convex microstructures. According to the present invention, this method can solve the problem of short service life of the electrostatic chuck caused by the previous processing methods and effectively improve the service life of the electrostatic chuck.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device manufacturing, and particularly to a processing method for the regular surface boss microstructures of an electrostatic chuck. Background Art

[0002] An electrostatic chuck is a key core component of semiconductor devices such as physical vapor deposition, chemical vapor deposition, and etching. The surface boss microstructures thereof determine the flatness of the electrostatic chuck for adsorbing wafers. However, after the electrostatic chuck is used for a certain period of time, the surface microstructures will be worn, resulting in uneven distribution of electrostatic adsorption force, warping of the wafer, and inability to ensure the processing accuracy of subsequent wafer manufacturing processes. Since electrostatic chucks are expensive, in order to reduce production costs, the worn electrostatic chucks are usually returned to the factory for repair and reprocessed to create new surface boss microstructures. The existing method for repairing the surface boss microstructures of a ceramic electrostatic chuck is to use a sandblasting process, which requires removing all the boss microstructures and then continuing to remove 5 - 50 μm of ceramic material from the functional layer, and then creating new boss microstructures on the material surface. This method makes the limited - thickness functional layer become thinner with the increase in the number of repairs. When the ceramic functional layer is too thin, the electrostatic chuck will undergo high - voltage breakdown, and at this time, it can only be discarded, and an expensive new electrostatic chuck must be purchased again. Summary of the Invention

[0003] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide a processing method for the regular surface boss microstructures of an electrostatic chuck, which can solve the problem of short service life of the electrostatic chuck caused by the previous processing methods and effectively improve the service life of the electrostatic chuck. To achieve the above - mentioned purpose and other advantages, the present invention provides a processing method for the regular surface boss microstructures of an electrostatic chuck, including the following steps:

[0004] S1. Prepare a structured grinding wheel by laser processing;

[0005] S2. Perform multiple ion implantations on the surface of the electrostatic chuck functional layer to form multiple modified regions;

[0006] S3. Selectively grind and remove the multiple modified regions with the structured grinding wheel to form the final surface boss microstructures of the ceramic electrostatic chuck functional layer;

[0007] S4. First, perform minimum - wear - height grinding on the worn electrostatic chuck, grind the remaining surface boss microstructures of the electrostatic chuck functional layer to the same height as the lowest point, and then repeat the above steps S2 and S3 to complete the renovation and repair of the worn boss microstructures.

[0008] Preferably, step S2 specifically includes the following steps:

[0009] S21. Perform the first application of the masking film on the area of the surface of the electrostatic chuck functional layer that has no surface modification requirements to protect the boss microstructure area, forming the first unmodified area;

[0010] S22. Use an ion beam to perform surface modification on the area to be removed during the first grinding process on the surface of the electrostatic chuck functional layer, forming the first modified area;

[0011] S23. Remove the masking film applied for the first time, rotate the workpiece 90° along the axial direction, and perform the second application of the masking film on the area of the surface of the electrostatic chuck functional layer that has no surface modification requirements, forming the second unmodified area;

[0012] S24. Use the ion beam again to perform surface modification on the material area to be removed during the second grinding process.

[0013] Preferably, step S3 specifically includes the following steps:

[0014] S31. Selectively grind and remove the first modified area: Remove the masking film applied for the second time, and use a structured grinding wheel to selectively grind and remove the area of the first surface modification;

[0015] S32. Selectively grind and remove the second modified area: Rotate the workpiece 90° along the axial direction, and then use a structured grinding wheel to selectively grind and remove the area of the second surface modification. After completing the selective grinding and removal of the two surface modification areas, the final boss microstructure on the surface of the ceramic electrostatic chuck functional layer is formed.

[0016] Preferably, in step S4, for the electrostatic chuck with boss microstructure wear after being used for a period of time, based on the height of the boss microstructure at the lowest point after wear, use an unstructured ordinary grinding wheel to grind the surface microstructure, and grind the remaining boss microstructures on the surface of the electrostatic chuck functional layer to the same height as the lowest point.

[0017] Preferably, in step S1, reverse solve the geometric dimensions and distribution spacing parameters of the structured grinding wheel groove structure through the boss microstructure characteristics on the surface of the electrostatic chuck functional layer to ensure that the processed structured grinding wheel can form a mapping relationship with the boss microstructure on the surface of the electrostatic chuck;

[0018] After obtaining the characteristic design parameters of the structured grinding wheel, use the laser ablation method to perform structured processing on the grinding wheel, and use a pulsed laser beam to trim a circumferentially perpendicular groove array structure on the circumferential surface of the grinding wheel to obtain the structured grinding wheel required for the boss processing of the electrostatic chuck.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: Aiming at the problem of the short service life of the convex microstructures on the surface of electrostatic chucks repaired by the sandblasting processing method, the present application proposes a new method of ion implantation surface modification-assisted structured grinding wheel selective grinding for processing the convex microstructures on the surface of ceramics. When using this method to repair the worn electrostatic chuck, it is not necessary to remove all the convex microstructures, and only deep processing on the basis of the original worn microstructures is required for repair, which will significantly improve the repair times and service life and reduce the usage cost of electrostatic chucks for enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. is a flow chart of a processing method for the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0021] Figure 2 FIG. is a size diagram of the convex structures on the surface of the functional layer of an electrostatic chuck for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0022] Figure 3 FIG. is a surface size diagram of a structured grinding wheel for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0023] Figure 4 FIG. is a diagram of a structured grinding wheel prepared by a laser ablation method for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0024] Figure 5 FIG. is a size requirement diagram for ion implantation for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0025] Figure 6 FIG. is a flow chart of a processing scheme for the surface functional layer of an electrostatic chuck for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention;

[0026] Figure 7 FIG. is a flow chart of a repair scheme for the convex microstructures on the surface of a worn electrostatic chuck for a processing method of the convex microstructures on the regular surface of an electrostatic chuck according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Refer to Figure 1-7, a processing method for the convex microstructure on the regular surface of an electrostatic chuck, comprising the following steps: S1. Prepare a structured grinding wheel by laser processing; first, reverse-solve the geometric dimensions, distribution pitch, and other parameters of the structured grinding wheel groove structure based on the convex microstructure features on the surface of the electrostatic chuck functional layer, ensuring that the processed structured grinding wheel can form a mapping relationship with the convex microstructure on the surface of the electrostatic chuck. During the processing of the structured grinding wheel, accurately match the convex microstructure on the target surface, save processing costs and time, improve production efficiency, and avoid multiple trial adjustments. After obtaining the characteristic design parameters of the structured grinding wheel, use the laser ablation method to perform structured processing on the grinding wheel, and use a pulsed laser beam to trim a circumferentially perpendicular groove array structure on the circumferential surface of the grinding wheel to obtain the structured grinding wheel required for the convex processing of the electrostatic chuck. Perform multiple selective grinding processes on the surface of the electrostatic chuck functional layer with the structured grinding wheel, effectively replicating the surface structure shape of the grinding wheel onto the surface of the electrostatic chuck functional layer, thereby realizing the mechanized and large-area generation of a micro-convex array. In actual production, using a structured grinding wheel can simply, efficiently, and economically process the regular surface microstructure on the electrostatic chuck functional layer.

[0029] S2. Perform multiple ion implantations on the surface of the electrostatic chuck functional layer to form multiple modified regions; by successively applying masks to the surface of the electrostatic chuck functional layer twice, mask the regions where convex microstructures need to be formed to ensure that during the subsequent ion implantation surface modification process, only the regions other than the masked regions are subjected to surface modification treatment, retaining the original characteristics of the masked region materials and forming an unmodified region. The unmasked regions on the surface of the electrostatic chuck are the regions to be processed and removed. After ion implantation, the lattice structure on the surface of the material to be removed is damaged to form irradiation damage, and the atomic arrangement changes. Through the cumulative fusion of defects such as vacancies and interstitial atoms, an amorphous modified layer with a certain thickness and consistent damage is generated. The formation of the modified layer can reduce material brittleness, improve its machining performance, improve the machining surface quality, and significantly reduce tool wear. Ion implantation surface modification of the ceramic material in the region to be removed "makes up for weaknesses with strengths" to solve the problems that the structured grinding wheel is prone to fragmentation and difficult to create convex microstructures when processing hard and brittle materials such as ceramics, providing the necessary conditions for the grindability of the ceramic surface when applying the structured grinding wheel to the convex microstructure processing of the electrostatic chuck.

[0030] S3. Selectively grind and remove multiple modified regions with a structured grinding wheel to form the final convex microstructure on the surface of the ceramic electrostatic chuck functional layer; select reasonable process parameters, and use the structured grinding wheel to selectively grind and remove the region to be removed in the first surface modification to form the first surface texture; then rotate the workpiece 90°, and under the same process parameters, use the structured grinding wheel to selectively remove the region to be removed in the second surface modification again to form the final convex microstructure on the surface of the electrostatic chuck.

[0031] S4. First, perform grinding on the electrostatic chuck with wear to the lowest wear height, grind the remaining boss microstructures on the surface of the functional layer of the electrostatic chuck to the same height as the lowest point, and then repeat the above steps S2 and S3 to complete the renovation and repair of the worn boss microstructures. First, use an unstructured ordinary grinding wheel, based on the height of the boss at the lowest point after wear, grind the remaining boss microstructures to the same height as the lowest point; then perform ion implantation on the surface of the boss microstructures with the lowest wear height twice separately, and use a structured grinding wheel to selectively remove the surface modification layers of the two ion implantations respectively, forming surface protrusion microstructures consistent with the new electrostatic chuck functional surface, thus forming a new repair process for the worn boss microstructures of the electrostatic chuck and extending the service life of the electrostatic chuck.

[0032] Further, step S2 specifically includes the following steps:

[0033] S21. Perform the first masking on the area of the surface of the functional layer of the electrostatic chuck that has no modification requirements to protect the boss microstructure area and form the first unmodified area;

[0034] S22. Use an ion beam to perform modification treatment on the area to be removed in the first grinding process on the surface of the functional layer of the electrostatic chuck to form the first modified area;

[0035] S23. Remove the first masking, rotate the workpiece 90° along the axial direction, and perform the second masking on the area of the surface of the functional layer of the electrostatic chuck that has no modification requirements to form the second unmodified area;

[0036] S24. Use the ion beam again to perform surface modification on the material area to be removed in the second grinding process.

[0037] Further, step S3 specifically includes the following steps:

[0038] S31. Selectively grind and remove the first modified area: Remove the second masking and use a structured grinding wheel to selectively grind and remove the first surface-modified area;

[0039] S32. Selectively grind and remove the second modified area: Rotate the workpiece 90° along the axial direction, and then use a structured grinding wheel to selectively grind and remove the second surface-modified area. After completing the selective grinding and removal of the two surface-modified areas, the final boss microstructures on the surface of the ceramic electrostatic chuck functional layer are formed.

[0040] Such as Figure 2As shown in the figure, the diameters Ф of the surface functional layer 1 and the substrate 3 of the electrostatic chuck are 300 mm. Uniformly spaced boss microstructures 2 are machined on the surface of the functional layer 1, and it is ensured that the lengths of the side lengths D of the upper surfaces of each boss microstructure 2 are the same. The specific parameter requirements are as follows: the height H of the boss microstructure 2 is 10 μm, the upper surface of each boss microstructure 2 is a square with a side length D of 1 mm, and the spacing P between the boss microstructures 2 is 9 mm.

[0041] As Figure 3 shown in the figure, the dimensions of the grooves on the circumferential curved surface of the structured grinding wheel 5 are determined based on the morphological characteristics of the boss microstructures 2 on the surface of the electrostatic chuck. During the grinding wheel processing, it is necessary to ensure that the morphological characteristics of the processed structured grinding wheel 5 can form a mapping relationship with the texture structure of the boss microstructures 2 formed on the surface functional layer 1 of the electrostatic chuck; at the same time, considering the influence of the wear of the grinding wheel and chip removal during the grinding process, it is required that the depth of the grooves 6 on the structured grinding wheel 5 should be greater than the height of the boss microstructures 2 on the surface of the electrostatic chuck functional layer. Therefore, when processing the grooves 6 on the circumferential surface of the structured grinding wheel, its depth a needs to exceed the height H = 10 μm of the boss microstructure 2, the width D of the groove 6 is equal to the side length of the boss microstructure 2, which is 1 mm, and the spacing P between the grooves 6 is equal to the spacing between adjacent boss microstructures 2, which is 9 mm. Therefore, the manufacturing process of the structured grinding wheel 5 needs to ensure that the width D and spacing P of the grooves 6 on its surface match the boss microstructures 2 on the surface 1 of the electrostatic chuck functional layer, so that effective processing of the surface 1 of the electrostatic chuck functional layer by the structured grinding wheel 5 can be achieved.

[0042] As Figure 4 shown in the figure, after obtaining the characteristic design parameters of the structured grinding wheel 5, the present invention selects the method of laser ablation to prepare the structure of the grinding wheel surface. The ordinary grinding wheel 4 to be trimmed and prepared is installed on the spindle of the machining center. The position of the galvanometer scanner 7 is adjusted so that the pulsed laser beam 8 is aligned with the tangential position of the point at the maximum radius of the grinding wheel, and then it is moved a certain distance a ≥ 10 μm along the radial direction of the grinding wheel. This distance is the cutting depth of the laser beam 8. The set scanning path width of the laser is the side length of the boss microstructure 2, which is 1 mm. The laser beam 8 is scanned and ablated on the circumferential surface of the grinding wheel to form grooves 6, and at the same time, compressed air is used as the auxiliary gas to remove the ablated material and further cool the processing surface. The circumferentially vertical groove structure 6 is obtained by trimming the circumferential surface of the grinding wheel with a pulsed laser.

[0043] As Figure 5As shown in the figure, when processing the surface functional layer 1 of the electrostatic chuck, first, a mask 9 is applied to the surface functional layer 1 of the electrostatic chuck for the first time to shield and protect the electrostatic chuck ceramic surface area 10 that does not require modification, and its width D is 1 mm. Subsequently, an ion beam is used to modify the area to be modified 11 of the part to be removed in the first surface modification. The electrostatic chuck is fixed to the fixture of the ion implanter, and ion implantation is sequentially performed on the area to be modified 11 of the part to be removed on the surface of the unshielded electrostatic chuck functional layer in the X direction from the figure. By adjusting the implantation parameters, the depth H of the surface modification is controlled to reach 10 μm. Remove the mask 9 applied for the first time, rotate the workpiece 90° along the axis, apply a mask 14 to the area 13 of the surface of the electrostatic chuck functional layer that does not require modification in the Y direction for the second time, and then use an ion beam to modify the area to be modified 15 of the part to be removed in the second surface modification. Finally, remove the mask 14 applied for the second time. By reasonably controlling the ion implantation parameters, a second surface modification layer 16 is obtained to improve the grindability of the material in the area to be removed.

[0044] As Figure 6 shown, the electrostatic chuck after the surface modification is fixed to the workbench of the machining center through a fixture. Align the initial position of the structured grinding wheel 5 with the first modified area 12 to be ground and removed on the surface of the electrostatic chuck functional layer. Use the structured grinding wheel 5 to selectively grind and remove the area 12 of the first ion beam surface modification through the set working path. Then, rotate the workpiece 90° along the axis, fix and align the structured grinding wheel 5 with the initial machining position of the second modified area 16 to be ground on the surface of the electrostatic chuck functional layer again, and selectively remove the area 16 of the second ion beam surface modification. Use the structured grinding wheel 5 to complete the selective grinding and removal of the two modified parts (12 and 16) on the surface of the electrostatic chuck functional layer, thereby realizing the processing of the boss microstructure 2 on the surface 1 of the electrostatic chuck ceramic functional layer.

[0045] As Figure 7As shown, a laser confocal scanning microscope, a high-definition CCD camera, etc. are used to measure the topography of the boss microstructures on the surface of the electrostatic chuck after wear, and the height information of the lowest boss microstructure 17 generated due to severe wear is obtained. An unstructured ordinary grinding wheel 4 is used to process the boss microstructures on the worn surface of the electrostatic chuck, and the remaining worn boss microstructures are ground to the same height as the lowest boss microstructure 17, unifying the height of the boss microstructures. This method can retain the boss microstructures with a certain height, without removing all the microstructures, reduce the loss of the functional layer, increase the number of repairable times, and thus extend the service life of the electrostatic chuck. After grinding the worn boss microstructures flat to the same as the lowest boss microstructure, two more ion implantations are performed on the surface of the boss microstructure with the lowest wear height. At this time, the implantation depth is H minus the height of the lowest microstructure 17. The structured grinding wheel 5 is used to selectively remove the surface modification layers of the two ion implantations at this depth, forming a height H that is the same as the surface boss microstructure of the functional layer of the new electrostatic chuck, completing the repair of the boss microstructures of the worn electrostatic chuck.

[0046] The equipment quantities and processing scales described herein are used to simplify the description of the present invention, and the applications, modifications, and variations of the present invention will be obvious to those skilled in the art.

[0047] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. A processing method for the convex microstructure on the regular surface of an electrostatic chuck, characterized in that It includes the following steps: S1. Prepare a structured grinding wheel by laser processing; S2. Perform multiple ion implantations on the surface of the electrostatic chuck functional layer to form multiple modified regions; S3. Selectively grind and remove the multiple modified regions with the structured grinding wheel to form the final convex microstructures on the surface of the ceramic electrostatic chuck functional layer; S4. For the electrostatic chuck with worn convex microstructures, first perform the lowest wear height grinding, grind the remaining convex microstructures on the surface of the electrostatic chuck functional layer to the same height as the lowest point, and then repeat the above steps S2 and S3 to complete the renovation and repair of the worn convex microstructures.

2. The processing method of the regular surface boss microstructure of an electrostatic chuck according to claim 1, characterized in that, Step S2 specifically includes the following steps: S21. Perform the first masking on the area of the electrostatic chuck functional layer surface without modification requirements to protect the convex microstructure area and form the first unmodified area; S22. Use an ion beam to modify the area to be removed during the first grinding process on the surface of the electrostatic chuck functional layer to form the first modified area; S23. Remove the first masking, rotate the workpiece 90° along the axis, and perform the second masking on the area of the electrostatic chuck functional layer surface without modification requirements to form the second unmodified area; S24. Use the ion beam again to perform surface modification on the material area to be removed during the second grinding process.

3. The processing method of the convex platform microstructure on the regular surface of an electrostatic chuck according to claim 2, wherein, Step S3 specifically includes the following steps: S31. Selectively grind and remove the first modified area: Remove the second masking, and use the structured grinding wheel to selectively grind and remove the first surface-modified area; S32. Selectively grind and remove the second modified area: Rotate the workpiece 90° along the axis, and then use the structured grinding wheel to selectively grind and remove the second surface-modified area. After completing the selective grinding and removal of the two surface-modified areas, the final convex microstructures on the surface of the ceramic electrostatic chuck functional layer are formed.

4. The processing method of the convex microstructure on the regular surface of an electrostatic chuck according to claim 3, characterized in that, In step S4, for the electrostatic chuck with convex microstructure wear after being used for a period of time, based on the height of the convex microstructure at the lowest point after wear, use an unstructured ordinary grinding wheel to grind the surface microstructure, and grind the remaining convex microstructures on the surface of the electrostatic chuck functional layer to the same height as the lowest point.

5. The processing method of the regular surface boss microstructure of an electrostatic chuck according to claim 4, characterized in that, In step S1, reverse solve the geometric dimensions and distribution spacing parameters of the structured grinding wheel groove structure through the convex microstructure characteristics on the surface of the electrostatic chuck functional layer to ensure that the processed structured grinding wheel can form a mapping relationship with the convex microstructures on the electrostatic chuck surface; After obtaining the characteristic design parameters of the structured grinding wheel, use the laser removal method to perform structured processing on the grinding wheel, and use a pulsed laser beam to trim a circumferentially perpendicular groove array structure on the circumferential surface of the grinding wheel to obtain the structured grinding wheel required for the convex processing of the electrostatic chuck.

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