CN116423384B - Electrochemical mechanical polishing head and polishing device - Google Patents
Electrochemical mechanical polishing head and polishing device Download PDFInfo
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- CN116423384B CN116423384B CN202310307906.7A CN202310307906A CN116423384B CN 116423384 B CN116423384 B CN 116423384B CN 202310307906 A CN202310307906 A CN 202310307906A CN 116423384 B CN116423384 B CN 116423384B
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- 238000005498 polishing Methods 0.000 title claims abstract description 164
- 239000000463 material Substances 0.000 claims abstract description 30
- 239000000523 sample Substances 0.000 claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 239000010949 copper Substances 0.000 claims description 8
- 239000003792 electrolyte Substances 0.000 claims description 8
- 239000011810 insulating material Substances 0.000 claims description 5
- -1 polytetrafluoroethylene Polymers 0.000 claims description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 4
- 238000003487 electrochemical reaction Methods 0.000 abstract description 11
- 239000004065 semiconductor Substances 0.000 abstract description 11
- 238000009826 distribution Methods 0.000 abstract description 6
- 238000003754 machining Methods 0.000 abstract description 4
- 230000000295 complement effect Effects 0.000 abstract description 3
- 230000009471 action Effects 0.000 abstract description 2
- 230000003647 oxidation Effects 0.000 abstract description 2
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- 239000002245 particle Substances 0.000 abstract 1
- 235000012431 wafers Nutrition 0.000 description 45
- 230000000052 comparative effect Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 10
- 238000012545 processing Methods 0.000 description 9
- 239000000126 substance Substances 0.000 description 6
- 230000003746 surface roughness Effects 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 239000006061 abrasive grain Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000002161 passivation Methods 0.000 description 3
- 238000007517 polishing process Methods 0.000 description 3
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 2
- DHMQDGOQFOQNFH-UHFFFAOYSA-N Glycine Chemical compound NCC(O)=O DHMQDGOQFOQNFH-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000003945 anionic surfactant Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004471 Glycine Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
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- 238000010292 electrical insulation Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000006056 electrooxidation reaction Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
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- 238000004439 roughness measurement Methods 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/30—Polishing of semiconducting materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
- B24B37/07—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool
- B24B37/10—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for single side lapping
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/27—Work carriers
- B24B37/30—Work carriers for single side lapping of plane surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
- B24B7/20—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground
- B24B7/22—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain
- B24B7/228—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain for grinding thin, brittle parts, e.g. semiconductors, wafers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30625—With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
The invention relates to an electrochemical mechanical polishing head and a polishing device, wherein the electrochemical mechanical polishing head comprises a polishing head main body and a working electrode fixed in the polishing head main body; the working electrode comprises a first split body and a second split body which are tightly attached, and a mounting groove is formed in the first split body; the second split body is provided with a structure which is profiled with the mounting groove and is embedded in the mounting groove; after the second split body is mounted to the mounting groove and the working electrode is mounted to the avoiding groove, the surfaces of the polishing head main body, the first split body and the second split body are flush; according to the invention, the working electrode in the electrochemical reaction is set to be in a split structure, the pressure and potential complementary distribution can be controlled, the electrochemical reaction degree and the machining strength are balanced, the high-efficiency polishing of the semiconductor wafer is realized under the combined action of anodic oxidation and abrasive particle mechanical removal, the material removal uniformity and the material removal rate are improved, and the product surface morphology advantage is obvious.
Description
Technical Field
The invention relates to the technical field of ultra-precise polishing, in particular to an electrochemical mechanical polishing head and a polishing device.
Background
The third generation semiconductor materials such as gallium nitride (GaN), silicon carbide (SiC) and the like are widely applied to the manufacture of semiconductor devices in the advanced scientific fields such as integrated circuit manufacture, precision optics, aerospace, communication, automobiles and the like due to the advantages of wide band gap, high breakdown field strength, high thermal conductivity and the like, and the fields have extremely high requirements on parameters such as crystal processing surface defects, surface roughness, subsurface or surface damage, residual stress, lattice integrity, surface type precision and the like of the semiconductor materials, however, the materials have high hardness, large brittleness, poor impact resistance and high processing difficulty; therefore, how to improve the processing quality and efficiency and obtain an ultra-smooth and undamaged atomic-scale surface is a problem to be solved in the manufacture of semiconductor devices; among them, an ultra-smooth surface is generally considered as a surface having no surface breakage scratch, no subsurface damage, no surface stress, and a surface roughness having a root mean square value of less than 1nm.
Chemical mechanical polishing CMP (CHEMICAL MECHANICAL polishing) is performed on the surface of a semiconductor wafer by rotating the polishing pad, and adding a polishing liquid abrasive containing abrasive grains. With the higher demands of the application field on wafer processing, many physical means are used to improve the polishing process in combination with CMP, and electrochemical mechanical polishing (ECMP) is one of them, which uses electrochemical reaction to etch the anode surface and remove the oxide layer on the material surface; in this polishing mode, the arrangement of the electrode structure directly affects the wafer processing efficiency and polishing effect.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the technical difficulty that the arrangement of the electrode structure of the polishing head in the ECMP of electrochemical mechanical polishing influences the processing efficiency and the effect in the prior art, and provide the electrochemical mechanical polishing head and the polishing device, which control the electrode potential and the pressure complementation distribution of the polishing head and improve the processing efficiency and the polishing effect.
In a first aspect, the present invention provides an electrochemical mechanical polishing head, comprising,
The polishing head comprises a polishing head main body, wherein the center of one surface of the polishing head main body is provided with an avoidance groove
The working electrode is fixed in the avoidance groove; the working electrode comprises a first split body and a second split body which are tightly attached, wherein the first split body is arranged as electrode metal, and the second split body is arranged as insulating material; the first split body is internally provided with a mounting groove, and the direction of the notch of the mounting groove is the same as that of the notch of the avoidance groove; the second split body is provided with a structure which is profiled with the mounting groove and is embedded in the mounting groove; after the second split is mounted to the mounting groove and the working electrode is mounted to the avoidance groove, the polishing head main body, the first split and the second split are flush in surface.
In one embodiment of the invention, the polishing head main body is of a columnar structure, the polishing head main body comprises a first end face and a second end face which are oppositely arranged along the axial direction, the first end face is provided with the avoidance groove, the avoidance groove is provided with a columnar groove, and the working electrode is provided with a column body contoured with the avoidance groove.
In one embodiment of the present invention, the second split is configured as a conical structure, the mounting groove is configured as a conical groove contoured to the conical surface of the second split, and the polishing head body, the first split, and the second split are coaxially disposed.
In one embodiment of the present invention, the electrochemical mechanical polishing head is provided with a fixing hole parallel to the axial direction thereof, a fastener is penetrated in the fixing hole, the fastener is used for communicating and fixing the polishing head main body, the first split body and the second split body, and the fastener has conductivity.
In one embodiment of the invention, the polishing head main body is provided with at least two probe holes parallel to the axis direction of the polishing head main body, the probe holes are arranged in the polishing head main body and are positioned in the area outside the avoidance groove, and metal probes or conductive screws are arranged in the probe holes.
In one embodiment of the present invention, the polishing head main body is further provided with a conductive groove, the conductive groove is communicated with the probe hole and the fixing hole at the second end face, and the conductive groove is a linear groove arranged along the radial direction of the second end face.
In one embodiment of the present invention, the second end surface is provided with a mounting screw hole, and the polishing head body is connected to the polishing shaft connection member through the mounting screw hole.
In one embodiment of the present invention, the first split is made of copper, and the second split is made of polytetrafluoroethylene.
In a second aspect, the present invention further provides an electrochemical mechanical polishing apparatus, including an electrochemical mechanical polishing head according to the foregoing embodiment, where a wafer to be polished is located on a surface of the electrochemical mechanical polishing head on which the avoiding groove is provided.
In one embodiment of the present invention, the electrochemical mechanical polishing apparatus includes a dc regulated power supply and a counter electrode, the working electrode is connected to a positive electrode of the dc regulated power supply, and the counter electrode is connected to a negative electrode of the dc regulated power supply and is fixed with a polishing pad; the working electrode and the counter electrode are arranged in the electrolyte in a facing way, and the electrochemical mechanical polishing head applies pressure to enable the wafer to be polished to be in contact with the polishing pad.
Compared with the prior art, the technical scheme of the invention has the following advantages:
According to the electrochemical mechanical polishing head and the polishing device, the conductor material and the insulating material are tightly attached, the working electrode in the electrochemical reaction is of a split structure, compared with the existing metal electrode, the pressure and potential distribution can be better controlled, the potential of a region with larger force application is relatively low, the potential of a region with smaller force application is relatively high, the complementary advantages of electrochemical reaction degree and mechanical processing strength are formed, the efficient polishing of a semiconductor wafer is realized under the combined action of anodic oxidation and abrasive grain mechanical removal, the removal uniformity and the removal rate of the material are improved, and the surface morphology advantages of a product are obvious.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which:
FIG. 1 is a schematic view of an electrochemical mechanical polishing head according to an embodiment of the present invention;
FIG. 2 is an isometric cross-sectional view of an electrochemical mechanical polishing head according to one embodiment of the invention;
FIG. 3 is a schematic view showing a structure in which an electrochemical mechanical polishing head is coupled to a polishing shaft coupling member according to a first embodiment of the present invention;
FIG. 4 is an exploded view of the electrochemical mechanical polishing head and polishing shaft connection of FIG. 3;
FIG. 5 is a schematic diagram of a surface roughness measurement point of a wafer according to a second embodiment of the present invention;
FIG. 6 is a graph showing the topography of the polished wafer of comparative examples 1-4 in example two of the present invention.
Description of the specification reference numerals: 1. an electrochemical mechanical polishing head; 2. a polishing head body; 21. a first end face; 22. a second end face; 23. an avoidance groove; 3. a working electrode; 31. a first split; 32. a second split; 33. a mounting groove; 4. a fixing hole; 5. a probe hole; 6. a conductive groove; 7. installing a screw hole; 8. and polishing the shaft connection.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Example 1
Referring to fig. 1 to 4, the present invention provides an electrochemical mechanical polishing head 1 for a reaction anode of an electrochemical mechanical polishing (ECMP) apparatus, which applies pressure to a semiconductor wafer held at the anode and provides an electric potential to polish the surface of the wafer.
When the chemical mechanical polishing CMP device is used, the polishing head is used for applying pressure to the semiconductor wafer to enable the semiconductor wafer to be in contact with the polishing pad for polishing, so that the pressure distribution on the surface of the polishing head can directly influence the material removal uniformity of the surface of the wafer, the wafer is extremely easily damaged when the applied pressure is high to cause defects, the ideal polishing effect cannot be achieved when the applied pressure is low, and the control of the pressure is important for the polishing process; as semiconductor wafer sizes increase, pressure loading non-uniformity issues are more pronounced; yanwu and other students use a zonal pressurizing technology to uniformly distribute the pressure on the polishing head, but the zonal pressurizing structure is required to be a multi-chamber pneumatic pressurizing structure and accurately control the real-time pressure of each chamber, so that the requirement on the structure of the polishing head is high; in addition, a learner designs a control system to automatically calibrate the pressure of each partition chamber, so that the design difficulty and the manufacturing cost are improved. The inventor of the present invention has found through research that when polishing a wafer by using an ECMP device, the problem of influence of uneven pressure distribution on polishing effect is also existed, and meanwhile, the electric potential of the polishing head surface of the ECMP integrated device is also not uniformly distributed.
Referring to fig. 2 and 4, the electrochemical mechanical polishing head 1 provided by the invention comprises a polishing head body 2 and a working electrode 3 embedded in the polishing head body 2; an avoidance groove 23 is formed in the center of one surface of the polishing head main body 2, and the working electrode 3 is fixed in the avoidance groove 23; the working electrode 3 comprises a first split body 31 and a second split body 32 which are closely attached, wherein the first split body 31 is arranged as electrode metal, and the second split body 32 is arranged as insulating material; a mounting groove 33 is formed in the first split body 31, and the notch direction of the mounting groove 33 is the same as the notch direction of the avoidance groove 23; the second split body 32 has a structure contoured to the mounting groove 33 and is embedded in the mounting groove 33; after the second split body 32 is mounted to the mounting groove 33 and the working electrode 3 is mounted to the avoiding groove 23, the surfaces of the polishing head main body 2, the first split body 31 and the second split body 32 are flush; the end face of the notch of the mounting groove 33, the surface of the second split body 32 away from the mounting groove 33, and the surface of the polishing head main body 2, which is provided with the avoiding groove 23, are flush, so as to be convenient for contact with the wafer surface.
Specifically, referring to fig. 1 and 4, in some preferred embodiments of the present invention, the polishing head body 2 is configured as a columnar structure, the polishing head body 2 includes a first end surface 21 and a second end surface 22 that are disposed opposite to each other along an axial direction, the first end surface 21 is provided with the escape groove 23, the escape groove 23 is configured as a columnar groove, and the working electrode 3 is configured as a column that is contoured to the escape groove 23; the second sub-body 32 is provided with a conical structure, and the mounting groove 33 is provided with a conical groove which is profiled with the conical surface of the second sub-body 32; the existing ECMP device uses a cylindrical pure copper material as the working electrode 3, which has the problem of uneven potential distribution, and in the preferred embodiment of the present invention, the surface of the working electrode 3 flush with the polishing head main body 2 includes a circular metal outer ring and an internal insulating material, which is adapted to the wafer size; the polishing head body 2, the first split body 31 and the second split body 32 are coaxially provided to apply force more uniformly.
Specifically, referring to fig. 1 and 2, the electrochemical mechanical polishing head 1 is provided with a fixing hole 4 parallel to the axis direction thereof, the fixing hole 4 is in a through hole structure, the fixing hole 4 is communicated with the polishing head main body 2, the first split body 31 and the second split body 32 in the extending direction thereof, and a fastener is penetrated in the fixing hole 4 for fixing the polishing head main body 2 and the working electrode 3; the fastener is electrically conductive and in some embodiments may be an electrically conductive screw that provides an electrical potential to the working electrode 3. In one embodiment, the electrochemical mechanical polishing head 1 is provided with two fixing holes 4, the two fixing holes 4 are symmetrically arranged at two sides of the center of the cross section of the polishing head, so that the connection strength between the polishing head main body 2 and the working electrode 3 is increased, and the electric potential is uniformly provided. In other implementations of the present embodiment, the fixing holes 4 are each disposed symmetrically around the center on the cross section of the electrochemical mechanical polishing head 1, and the number and positions thereof are not limited thereto.
Further, in some embodiments, referring to fig. 1 and fig. 2, when the electrical conductivity of the wafer to be polished is low, at least two probe holes 5 are further provided in the direction parallel to the axis of the polishing head main body 2, the probe holes 5 are in a through hole structure, and are disposed in a region outside the avoiding groove 23 in the polishing head main body 2, the probe holes 5 are communicated with the first end surface 21 and the second end surface 22, and metal probes or conductive screws are disposed in the probe holes 5, so that the electrochemical etching degree is enhanced; further, referring to fig. 1, when the electrochemical mechanical polishing head is provided with the probe hole 5, the polishing head main body 2 is further provided with a conductive groove 6 for communicating the probe hole 5 and the fixing hole 4, the conductive groove 6 is provided with a blind groove structure located on the second end face 22, and preferably, the conductive groove 6 is designed to be a linear groove along the radial line direction of the second end face 22, so that the conductivity and the electrochemical reaction degree are enhanced; the number of the probe holes 5 can be adjusted according to the conductivity of the material to be polished, and the probe holes 5 are symmetrically arranged around the center on the cross section of the electrochemical mechanical polishing head 1, not limited to the above; it is noted that when the conductivity of the material is high, the electrochemical reaction degree is adapted to the polishing requirement, and only the fixing hole 4 and the conductive groove 6 between the fixing holes 4 are provided to provide electrode potential, and the probe hole 5 and the conductive groove 6 communicating the probe hole 5 and the fixing hole 4 are not provided.
Specifically, referring to fig. 1 and 3, the second end surface 22 is provided with at least three mounting screw holes 7, the mounting screw holes 7 are located at the projection periphery of the working electrode 3 on the second end surface 22, the mounting screw holes 7 are provided with a blind hole structure, one end in the extending direction of the mounting screw holes is located at the second end surface 22, the other end in the extending direction of the mounting screw holes is located in the polishing head main body 2, and the mounting screw holes are located in a region outside the avoiding groove 23; the polishing head main body 2 is provided with a fixing screw through the mounting screw hole 7 so as to be connected with a polishing shaft connecting piece 8, and is connected with other devices through the polishing shaft connecting piece 8.
Specifically, ECMP combines electrochemical reaction and machining technology to act on the surface of a wafer together, the surface of the wafer to be polished is rusted into a passivation film by oxidation-reduction reaction, then oxide on the surface is ground and decomposed by machining to be flattened, passivation and removal are repeated for a plurality of times, so that the surface roughness of the wafer is reduced, ECMP is not limited by the hardness and toughness of materials, and various wafers can be polished. Since the electrochemical reaction is introduced into the polishing process, the contact area of the working electrode 3 and the wafer surface is located at the edge of the wafer, resulting in uneven potential across the wafer surface, and the removal rate of the wafer edge is higher than that of the wafer center; in the embodiment of the present invention, the material of the first split body 31 is copper, the conductive performance and the mechanical performance are good, and the cost is low, and the material of the second split body 32 is polytetrafluoroethylene, which has electrical insulation property, good chemical stability and corrosion resistance, and shows inertia to most chemicals and solvents. The polytetrafluoroethylene has lower density, weaker dynamic impact mechanical property, higher relative density of copper material and stronger impact mechanical property. When the working electrode 3 is in contact with the surface of the wafer, a certain pressure is applied to the wafer, and as an anode material, a part of the wafer corresponding to a region with lower potential is easily oxidized to form a passivation film, and the region corresponds to higher applied pressure and higher machining strength; the invention ensures that the potential strength and the force application are complementary and uniformly distributed, thereby ensuring that the polishing effect of each area on the surface of the wafer tends to be consistent; in some implementations of this embodiment, the second split 32 is conical, and the thicknesses of the first split 31 and the second split 32 in the radial direction of the wafer are all linearly changed, so that the pressure and the potential are also gradually changed, and the mechanical processing strength and the electrochemical reaction strength are balanced with each other; the polishing effect is approximately consistent at the same position with the center distance of the wafer. By using the electrochemical mechanical polishing head 1 of the embodiment, the unbalance of pressure and potential can be avoided from damaging the surface of the wafer, meanwhile, insufficient polishing effect is avoided, the uniformity and the rate of removal of the surface of the wafer material are improved, and the polishing efficiency is improved.
Example two
The embodiment of the invention also provides an electrochemical mechanical polishing device, which comprises the electrochemical mechanical polishing head 1 according to any embodiment, wherein a wafer to be polished is adsorbed on the surface of one side, provided with the avoidance groove 23, of the electrochemical mechanical polishing head 1 through an adsorption pad; the electrochemical mechanical polishing device further comprises an electrolyte tank, an external direct-current stabilized power supply and a counter electrode, wherein the working electrode 3 is connected to the positive electrode of the direct-current stabilized power supply through a wire, the counter electrode is connected to the negative electrode of the direct-current stabilized power supply through a wire, and a polishing pad is further fixed on the counter electrode; the polishing pad, the wafer to be polished and the counter electrode are immersed in polishing electrolyte, the working electrode 3 and the counter electrode are arranged in the electrolyte in a right opposite way to form an electrochemical reaction, and the electrochemical mechanical polishing head 1 applies pressure to enable the wafer to be polished to be contacted with a certain pressure and pressed on the surface of the polishing pad; the electrochemical mechanical polishing head 1 is driven by a motor, the polishing pad is made of porous materials, and the counter electrode can be made of graphite or other electrode materials meeting the actual reaction requirements.
The working principle of the electrochemical mechanical polishing device according to this embodiment is as follows:
Taking a 2 inch gallium nitride wafer as an example, the wafer is treated with 4wt% hard abrasive grain silicon carbide before polishing to destroy the original surface structure. The polishing time was controlled to be 30min each time. The polishing solution consists of oxidant hydrogen peroxide H 2O2, abrasive grain silicon dioxide SiO 2 and complexing agent glycine, and the pH value is regulated to 10.5 by using organic alkali. According to the working principle of ECMP integrated equipment, electrolyte sodium chloride NaCl with the mass fraction of 5wt% is added into the polishing solution, and because electrochemical corrosion is stronger than conventional chemical corrosion, an appropriate amount of corrosion inhibitor PTA is added to prevent excessive corrosion.
The polishing time, polishing electrolyte composition, wafer size and pretreatment steps were controlled to be consistent, a cylindrical structure working electrode of pure copper material was used, and an electrochemical mechanical polishing apparatus was powered off to be used as comparative example 1, simulating a conventional CMP experiment.
The same experimental conditions as in comparative example 1 were set, and only the ECMP apparatus in comparative example 1 was energized for use, simulating the existing ECMP experiment using the conventional electrode set, as comparative example 2.
The same experimental conditions as in comparative example 2 were set, and only the working electrode in comparative example 2 was replaced with the working electrode 3 provided in the example of the present invention from the cylindrical structure of pure copper material, and an ECMP experiment was performed as comparative example 3.
The same experimental conditions as in comparative example 3 were set, and an ECMP experiment was performed as comparative example 4 by adding an anionic surfactant to the polishing electrolyte based on comparative example 3 and adaptively adjusting part of the equipment parameters.
The electrochemical mechanical polishing apparatus of the present invention was used in this example to characterize the polishing effect in terms of sample surface roughness Ra, removal uniformity MRU (material removal uniformity), and removal rate index MRR (material removal rate).
Specifically, each wafer is positioned by taking a notch of the wafer as a center, the notch is taken as a measuring point, two groups of different measuring distances are set, eight measuring points which are the measuring distances with the notch are determined on two orthogonal radial lines passing through the notch, and the total of nine measuring points are determined; preferably, referring to fig. 5, in this embodiment, the eight measurement points are all located at the trisection points of the orthogonally arranged radii, each measurement point measures the roughness in the range of 10 μm by 10 μm, and the average value of the 9 finally obtained roughness data x i is the surface roughness Ra of the sample.
Taking a standard deviation of the 9 roughness data x i, representing the deviation degree of a plurality of data and the mean value Ra thereof, keeping the dimension consistent with the Ra energy, describing the removal uniformity MRU of the material by the standard deviation, wherein the lower the numerical value of the MRU is, the better the uniformity of the surface of the material is, the calculation formula of the removal uniformity MRU is as follows,
The experimental results of comparative examples 1 to 4 are shown with reference to table 1, and the surface morphology of the materials is shown with reference to fig. 6; as can be seen from comparative examples 1 and 2, the advantages of ECMP over CMP are evident, both in terms of material removal rate and material surface quality after polishing; compared with the existing pure copper metal polishing head electrode, the working electrode 3 with the split structure is improved in material removal rate, and the polished material has more remarkable surface morphology advantages, and particularly good surface uniformity index. It is known from the supplement of comparative example 4 that the adjustment of the anionic surfactant and the process parameters of the apparatus can further enhance the polishing effect when the ECMP apparatus according to the embodiment of the present invention is used for polishing wafers. In summary, according to the electrochemical mechanical polishing device provided by the embodiment of the invention, the technical problem of poor wafer polishing consistency can be better solved through mutual complementation of potential and pressure, and the removal rate and the wafer surface morphology are better improved.
TABLE 1
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (5)
1. An electrochemical mechanical polishing head, comprising,
The polishing device comprises a polishing head main body, wherein an avoidance groove is formed in the center of one surface of the polishing head main body;
The working electrode is fixed in the avoidance groove; the working electrode comprises a first split body and a second split body which are tightly attached, wherein the first split body is arranged as electrode metal, and the second split body is arranged as insulating material; the first split body is internally provided with a mounting groove, and the direction of the notch of the mounting groove is the same as that of the notch of the avoidance groove; the second split body is provided with a structure which is profiled with the mounting groove and is embedded in the mounting groove; after the second split body is mounted to the mounting groove and the working electrode is mounted to the avoiding groove, the surfaces of the polishing head main body, the first split body and the second split body are flush;
The polishing head comprises a polishing head body, a working electrode and a polishing head body, wherein the polishing head body is of a columnar structure and comprises a first end face and a second end face which are oppositely arranged along the axial direction, the first end face is provided with an avoidance groove, the avoidance groove is arranged as a columnar groove, and the working electrode is arranged as a cylinder copying with the avoidance groove;
The second split body is in a conical structure, the mounting groove is a conical groove which is contoured with the conical surface of the second split body, and the polishing head main body, the first split body and the second split body are coaxially arranged;
The electrochemical mechanical polishing head is provided with a fixing hole parallel to the axis direction of the electrochemical mechanical polishing head, a fastener is penetrated in the fixing hole and used for communicating and fixing the polishing head main body, the first split body and the second split body, and the fastener has conductivity;
The polishing head main body is provided with at least two probe holes parallel to the axis direction of the polishing head main body, the probe holes are arranged in the polishing head main body and are positioned in areas outside the avoidance grooves, and metal probes or conductive screws are arranged in the probe holes;
The polishing head main body is further provided with a conductive groove, the conductive groove is communicated with the probe hole and the fixing hole through the second end face, and the conductive groove is a linear groove arranged along the radial line direction of the second end face.
2. An electrochemical mechanical polishing head according to claim 1, wherein: the second end face is provided with a mounting screw hole, and the polishing head main body is connected with the polishing shaft connecting piece through the mounting screw hole.
3. An electrochemical mechanical polishing head according to claim 1, wherein: the material of the first split body is copper, and the material of the second split body is polytetrafluoroethylene.
4. An electrochemical mechanical polishing apparatus comprising the electrochemical mechanical polishing head according to any one of claims 1 to 3, wherein a wafer to be polished is positioned on a surface of the electrochemical mechanical polishing head on which the avoiding groove is provided.
5. An electrochemical mechanical polishing apparatus according to claim 4, wherein: the polishing device comprises a direct-current stabilized power supply and a counter electrode, wherein the working electrode is connected to the positive electrode of the direct-current stabilized power supply, and the counter electrode is connected to the negative electrode of the direct-current stabilized power supply and is fixed with a polishing pad; the working electrode and the counter electrode are arranged in the electrolyte in a facing way, and the electrochemical mechanical polishing head applies pressure to enable the wafer to be polished to be in contact with the polishing pad.
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| JP4513145B2 (en) * | 1999-09-07 | 2010-07-28 | ソニー株式会社 | Semiconductor device manufacturing method and polishing method |
| US7374644B2 (en) * | 2000-02-17 | 2008-05-20 | Applied Materials, Inc. | Conductive polishing article for electrochemical mechanical polishing |
| US6689258B1 (en) * | 2002-04-30 | 2004-02-10 | Advanced Micro Devices, Inc. | Electrochemically generated reactants for chemical mechanical planarization |
| JP4465645B2 (en) * | 2003-06-03 | 2010-05-19 | 株式会社ニコン | Polishing apparatus and semiconductor device manufacturing method using the same |
| TW200801253A (en) * | 2006-04-14 | 2008-01-01 | Roki Techno Co Ltd | Polishing pad for device wafer |
| US20080188162A1 (en) * | 2007-02-06 | 2008-08-07 | Itsuki Kobata | Electrochemical mechanical polishing apparatus conditioning method, and conditioning solution |
| CN108666244A (en) * | 2018-05-15 | 2018-10-16 | 长江存储科技有限责任公司 | Bevel-etching device and wafer lithographic method |
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| CN115741423A (en) * | 2022-11-24 | 2023-03-07 | 苏州铼铂机电科技有限公司 | Polishing head device for chemical mechanical polishing machine |
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