CN117020926A - Electrochemical mechanical polishing device for silicon carbide wafer - Google Patents

Electrochemical mechanical polishing device for silicon carbide wafer Download PDF

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Publication number
CN117020926A
CN117020926A CN202311001576.5A CN202311001576A CN117020926A CN 117020926 A CN117020926 A CN 117020926A CN 202311001576 A CN202311001576 A CN 202311001576A CN 117020926 A CN117020926 A CN 117020926A
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China
Prior art keywords
polishing
wafer
silicon carbide
conductive
electrochemical mechanical
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CN202311001576.5A
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Chinese (zh)
Inventor
王磊
张康
邢朝月
崔云承
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Beijing Jingyi Precision Technology Co ltd
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Beijing Jingyi Precision Technology Co ltd
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Priority to CN202311001576.5A priority Critical patent/CN117020926A/en
Publication of CN117020926A publication Critical patent/CN117020926A/en
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    • 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
    • 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
    • B24B37/046—Lapping machines or devices; Accessories designed for working plane surfaces using electric current
    • 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
    • B24B37/105—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for single side lapping the workpieces or work carriers being actively moved by a drive, e.g. in a combined rotary and translatory movement
    • 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
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/34—Accessories
    • 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
    • H01L21/3063—Electrolytic etching

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

The invention provides an electrochemical mechanical polishing device for a silicon carbide wafer, which belongs to the technical field of electrochemical mechanical polishing and comprises a polishing table, a polishing head and an electrode assembly, wherein a polishing pad is arranged on the polishing table and is provided with a liquid passing hole; the polishing head is provided with an adsorption air bag which is used for adsorbing a wafer to be treated and applying acting force to the wafer to be treated; the electrode assembly comprises a first conductive piece and a second conductive piece, wherein the first conductive piece is arranged below the polishing pad, the second conductive piece is a sheet-shaped conductor, and the second conductive piece is arranged on the adsorption air bag. The invention utilizes the conductivity of silicon carbide, and the sheet-shaped conductor arranged on the adsorption air bag does not influence the adsorption of the wafer to be processed, and also completes the communication between the first conductive piece and the second conductive piece, thereby realizing the electrochemical mechanical polishing process when the wafer is fixed by adsorption.

Description

Electrochemical mechanical polishing device for silicon carbide wafer
Technical Field
The invention relates to the technical field of electrochemical mechanical polishing, in particular to an electrochemical mechanical polishing device for a silicon carbide wafer.
Background
With the rapid development of the electronic industry and the precision physics field, the polishing requirements of the wafer surface are more and more strict, and in order to avoid the problems of interfacial peeling and surface damage in the planarization process, the planarization process must be performed under low pressure or no stress. Compared with the traditional polishing technology, the electrochemical mechanical polishing (ECMP) has the obvious advantages of low polishing pressure, small wafer deformation and the like, and is the low-pressure high-efficiency planarization technology with the development potential at present.
Silicon carbide is used as a typical representative of third-generation semiconductor materials, has the advantages of large forbidden bandwidth, high thermal conductivity, high saturated electron migration rate and the like, is an ideal material for high-frequency, high-temperature, high-efficiency and high-power electronic components, and has wide application prospects in the scientific and technical fields of aerospace, new energy automobiles, 5G base stations and the like.
For the polishing process of silicon carbide, in patent CN114654380a, an electrochemical mechanical polishing method for a silicon carbide wafer is pointed out, the silicon carbide wafer is adhered to the lower surface of a copper polishing head through conductive adhesive, the copper polishing head is connected with the positive electrode of a power supply through a wire, namely the polishing head serves as a conductive element of the positive electrode, and the electrochemical process for the silicon carbide wafer is completed by matching with electrolyte; in most wafer polishing technologies, the wafer is generally fixed by vacuum adsorption, and in patent CN1233506C, the wafer is adsorbed and held by an air bag, and the air bag is made of a non-conductive material, and cannot conduct electricity by the polishing head itself, so that in the experiment of fixing the wafer by adsorption, the electrochemical process is difficult to complete.
Disclosure of Invention
Accordingly, the present invention has been made to solve the problem of how to perform electrochemical mechanical polishing on a silicon carbide wafer fixed by adsorption, and thus provides an electrochemical mechanical polishing apparatus for a silicon carbide wafer.
In order to solve the above technical problems, the present invention provides an electrochemical mechanical polishing apparatus for silicon carbide wafer, comprising:
a polishing table on which a polishing pad is disposed, the polishing pad having a liquid passing hole;
the polishing head is arranged above the polishing table, an adsorption air bag is arranged on the polishing head and is used for adsorbing a wafer to be treated and applying acting force to the wafer to be treated;
the electrode assembly comprises a first conductive piece and a second conductive piece, the first conductive piece is arranged below the polishing pad, the second conductive piece is a sheet-shaped conductor, and the second conductive piece is arranged on the adsorption air bag; when the wafer to be processed is adsorbed, a part of the wafer to be processed is connected with the second conductive piece, and when the wafer to be processed is polished, the wafer to be processed is electrically connected with the first conductive piece through electrolyte in the liquid passing hole.
Optionally, the polishing head is provided with fixing pieces extending downwards at the periphery of the adsorption air bag so as to fix the wafer to be processed; the bottom of the fixing piece is provided with a diversion trench.
Optionally, the polishing head further comprises:
the porous plate is arranged at the bottom of the polishing head and is provided with a via hole; the adsorption air bag is coated at the bottom of the porous plate;
the gas path channel is arranged inside the polishing head and communicated with the through hole and used for controlling the expansion and contraction of the adsorption air bag.
Optionally, the second conductive member is disposed at an edge of the adsorption balloon.
Optionally, the second conductive element has at least two groups of output points, and the output points are all arranged at the edge of the adsorption air bag.
Optionally, the second conductive piece is double-sided conductive foil paper, and the double-sided conductive foil paper is double-conductive aluminum foil paper or double-conductive tin foil paper.
Optionally, an electrically conductive slip ring is disposed on the polishing head, and the second conductive member is electrically connected with the electrically conductive slip ring through a wire.
Optionally, a wire via is provided on the polishing head, and a wire passing through the wire via connects the conductive slip ring and the second conductive member.
Optionally, the method further comprises:
the output end of the first driving component is connected with the polishing head so as to drive the polishing head to move;
and the output end of the second driving component is connected with the polishing head so as to drive the polishing head to rotate.
Optionally, the method further comprises:
and the output end of the third driving assembly is connected with the polishing table so as to drive the polishing table to rotate.
Optionally, the method further comprises:
and the spraying device is arranged above the polishing table and is used for spraying electrolyte to the polishing pad.
The technical scheme of the invention has the following advantages:
1. the invention provides an electrochemical mechanical polishing device for a silicon carbide wafer, which comprises a polishing table, a polishing head and an electrode assembly, wherein an adsorption air bag on the polishing head transfers the wafer to be processed to a polishing pad, the electrode assembly comprises a first conductive piece and a second conductive piece, the first conductive piece is arranged below the polishing pad, the second conductive piece is arranged on the adsorption air bag, the second conductive piece is a sheet-shaped conductive body, when the wafer to be processed is adsorbed, a part of the wafer to be processed is connected with the second conductive piece, when the wafer to be processed is polished, the wafer to be processed is electrically connected with the first conductive piece through electrolyte in a liquid hole, a blocking film for preventing the wafer to be processed from being further dissolved is generated on the surface of the wafer to be processed through electrochemical corrosion, and then the convex part of the blocking film is scraped through the mechanical action of the polishing pad and the electrolyte, so that the uneven part of the surface of the wafer to be processed is preferentially removed, and finally the global planarization of the wafer to be processed is realized.
By utilizing the conductivity of the silicon carbide, the adsorption of the wafer to be processed is not affected by the sheet-shaped conductor arranged on the adsorption air bag, the communication between the first conductive piece and the second conductive piece is completed, and the electrochemical mechanical polishing process performed when the wafer is fixed by adsorption is realized.
2. According to the electrochemical mechanical polishing device for the silicon carbide wafer, provided by the invention, the polishing head is provided with the fixing pieces extending downwards at the periphery of the adsorption air bag and used for fixing the wafer to be processed, so that the phenomenon that a sliding sheet appears due to the stress of the wafer to be processed in the moving polishing process, and the polishing effect is influenced is avoided;
the bottom of mounting is provided with the guiding gutter, and the guiding gutter is used for guiding the inflow of electrolyte to flow out, makes the more even contact wafer of treating of electrolyte, and is favorable to the rapid discharge of electrolyte.
3. The polishing head further comprises a porous plate, the porous plate is arranged at the bottom of the polishing head, the porous plate is provided with the through holes, the adsorption air bag is arranged at the bottom of the porous plate in a coating mode, the inside of the polishing head is provided with the air path channel, the air path channel is used for controlling the expansion and contraction of the adsorption air bag, and the porous plate and the through holes on the porous plate provide support for the adsorption air bag in the contraction process, so that the wafer to be processed is stable in the adsorption transfer process.
4. According to the electrochemical mechanical polishing device for the silicon carbide wafer, the second conductive piece is arranged at the edge of the adsorption air bag, when the wafer to be treated is adsorbed, only a part of the second conductive piece is contacted with the second conductive piece, so that the adsorption fixing process of the wafer is influenced due to too much contact, and the surface of the wafer is easily damaged.
5. According to the electrochemical mechanical polishing device for the silicon carbide wafer, the second conductive piece is provided with at least two groups of output points, the output points are uniformly distributed at the edge of the adsorption air bag, the electrochemical process can be realized by electric connection of any output point, and when one output point is accidentally disconnected in the moving process, the electrochemical process can be continuously performed by setting other output points.
6. According to the electrochemical mechanical polishing device for the silicon carbide wafer, the second conductive piece is double-sided conductive foil paper, and the double-sided conductive foil paper is double-conductive aluminum foil paper or double-conductive tin foil paper, so that the device has excellent conductive performance, is soft and thin, well adapts to the shrinkage of the adsorption air bag, and has a good effect, and the thickness of the device does not influence the adsorption of the wafer to be treated.
7. According to the electrochemical mechanical polishing device for the silicon carbide wafer, provided by the invention, the conductive slip ring is arranged on the polishing head, the second conductive piece is electrically connected with the conductive slip ring through the wire, the conductive slip ring can be arranged to avoid the problem of winding of the wire in the rotating process of the polishing head, and the system structure can be greatly simplified due to the conductive slip ring, so that the wire is prevented from being damaged in the rotating process.
8. According to the electrochemical mechanical polishing device for the silicon carbide wafer, the wire through hole is formed in the polishing head, the conducting wire penetrating through the wire through hole is connected with the conductive slip ring and the second conductive piece, and the situation that the conducting wire is worn in the polishing process to influence the implementation of the electrochemical process is avoided.
9. The silicon carbide wafer electrochemical mechanical polishing device provided by the invention further comprises a first driving component, a second driving component and a third driving component, wherein the first driving component drives the polishing head to move, the second driving component drives the polishing head to rotate, the third driving component drives the polishing table to rotate, and the polishing head performs rotary motion and reciprocating motion and is matched with the rotary polishing pad, so that the wafer to be processed is polished efficiently.
10. The electrochemical mechanical polishing device for the silicon carbide wafer, provided by the invention, further comprises a spraying device for spraying the electrolyte to the polishing pad, so that the polishing pad is not required to be soaked, the electrolyte is saved, the spraying and suspension of the electrolyte can be performed according to actual conditions, and the electrochemical mechanical polishing process can be better controlled.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of an embodiment of an electrochemical mechanical polishing apparatus for silicon carbide wafers according to an embodiment of the present invention;
FIG. 2 is a schematic view showing a first state of the polishing head in FIG. 1 when the polishing head is sucking a wafer to be processed;
FIG. 3 is a schematic view showing a second state of the polishing head in FIG. 1 when the polishing head is sucking a wafer to be processed;
FIG. 4 is a schematic view of the wafer to be processed and the polishing pad of FIG. 1 being polished in combination;
fig. 5 is a schematic structural diagram of the first conductive member in fig. 1.
Reference numerals illustrate:
1. a polishing table; 2. a polishing pad; 3. a liquid passing hole; 4. a polishing head; 5. an adsorption balloon; 6. a wafer to be processed; 7. a first conductive member; 8. a second conductive member; 9. a fixing member; 10. a diversion trench; 11. a porous plate; 12. a via hole; 13. an air path channel; 14. a conductive slip ring; 15. a wire via; 16. a wire; 17. a first drive assembly; 18. a second drive assembly; 19. a third drive assembly; 20. a spraying device; 21. a cathode contact; 22. a support table; 23. a baffle; 24. a weeping hole; 25. a recovery unit; 26. a filtering unit; 27. a storage unit; 28. a first flow control unit; 29. a temperature control unit; 30. a cleaning unit; 31. and a second flow control unit.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In integrated circuit fabrication, each layer in the wafer interconnect structure is highly planarized at the nanoscale, and wafer polishing processes have been a key factor in industry development. Current silicon carbide photofabrication processes include Chemical Mechanical Polishing (CMP), stress Free Polishing (SFP), ion Beam Planarization (IBP), or plasma assisted chemical etch Planarization (PACE).
CMP is a polishing technique that combines the action of two external forces, chemical and mechanical, in which a rotating workpiece is pressed against a polishing pad rotating with a platen with a certain pressure, and a polishing liquid composed of submicron or nano abrasive grains and a chemical solution flows between the workpiece and the polishing pad, and a layer of softened film is generated on the surface of a wafer, and the softened film formed on the surface of the wafer is removed by the mechanical friction action of the abrasive grains. However, the CMP process has the defects of large mechanical force, easy deformation, overpolishing, dishing, nitride corrosion and the like of the wafer under high polishing pressure, complex chemical components in the polishing solution of CMP, difficult treatment of waste liquid generated by polishing and serious environmental pollution.
The stress-free polishing is a planarization technology developed from the electrolytic polishing technology, and mainly depends on the current density effect to planarize the surface of the silicon carbide wafer in a series of concentric rings. A large amount of silicon carbide is removed by first electropolishing followed by secondary polishing to ensure complete removal of the top silicon carbide. The technology has no polishing pressure, but the material removal rate of each part of the wafer is inconsistent due to uneven voltage distribution between the electrolyte and the wafer in the polishing process, so that the surface flatness of the silicon carbide wafer can be influenced, and particularly, the influence on a large-size wafer is more remarkable.
Ion beam polishing is a high-precision surface treatment technology, which utilizes the high energy and high speed of ion beams to process and improve the surface of a wafer under the vacuum condition, and the ion beam polishing technology is widely applied to the fields of semiconductors, optics, aerospace, medical appliances and the like and becomes an indispensable part of the modern industry. Ion polishing has a higher material removal rate and can also increase the etch rate by using reactive gases. Ion beam polishing can improve polishing efficiency, but ion beam polishing equipment is complex and expensive, and is mainly applied to detection technology at present.
The plasma-assisted chemical etching technology is originally used for processing optical lenses and is now used for flattening silicon-based wafers, and the PACE technology is non-contact processing when flattening the silicon-based wafers, so that the method has the advantages of no damage layer, easiness in ensuring the surface type precision and the like. However, the technology has high cost and is not widely popular at present compared with the mainstream polishing technology.
In summary, the existing silicon carbide wafer polishing process cannot simultaneously consider three important indexes of improving polishing efficiency, controlling polishing quality and reducing polishing pressure in principle, while the electrochemical mechanical polishing process (ECMP) can simultaneously consider three key indexes of low polishing pressure, high polishing efficiency and small environmental pollution, and has great development space in the novel polishing process; however, because the wafer is adsorbed and held by the air bag, the air bag is made of a non-conductive material, and the polishing head cannot be used as a conductive piece, so that in an experiment of fixing the wafer by adsorption, the electrochemical process is difficult to complete, and therefore, the development of a novel planarization system for the silicon carbide wafer has great potential and practical value.
The electrochemical mechanical polishing device for the silicon carbide wafer is used for electrochemical mechanical polishing of the silicon carbide wafer.
As shown in fig. 1 to 4, a specific implementation manner of the electrochemical mechanical polishing device for silicon carbide wafer provided in this embodiment includes a polishing table 1, a polishing head 4 and an electrode assembly, where a polishing pad 2 is disposed on the polishing table 1, and the polishing pad 2 has a liquid through hole 3; the polishing head 4 is arranged above the polishing table 1, an adsorption air bag 5 is arranged on the polishing head 4, and the adsorption air bag 5 is used for adsorbing a wafer 6 to be treated and applying acting force to the wafer 6 to be treated; the electrode assembly comprises a first conductive piece 7 and a second conductive piece 8, wherein the first conductive piece 7 is arranged below the polishing pad 2, the second conductive piece 8 is a sheet-shaped conductive body, and the second conductive piece 8 is arranged on the adsorption air bag 5; when the wafer 6 to be processed is adsorbed, a part of the wafer 6 to be processed is connected with the second conductive piece 8, and when the wafer 6 to be processed is polished, the wafer 6 to be processed is electrically connected with the first conductive piece 7 through electrolyte in the liquid passing hole 3. Wherein, the polishing pad 2 is made of polyurethane, the first conductive piece 7 is a cathode conductive piece and is connected with the negative electrode of the power supply, and the second conductive piece 8 is an anode conductive piece and is connected with the positive electrode of the power supply.
When the electrochemical mechanical polishing device works, the wafer 6 to be treated is in contact with the polishing pad 2, the first conductive piece 7 and the second conductive piece 8 form a closed loop under the electric connection effect of electrolyte, a blocking film for preventing the wafer 6 to be treated from being further dissolved is generated on the surface of the wafer 6 to be treated through electrochemical corrosion effect, then the convex part of the blocking film is scraped through the mechanical effect of the polishing pad 2 and the electrolyte, so that the uneven part on the surface of the wafer 6 to be treated is preferentially removed, and the global planarization of the wafer 6 to be treated is finally realized. By utilizing the conductivity of silicon carbide, the adsorption of the wafer 6 to be processed is not affected by the sheet-shaped conductor arranged on the adsorption air bag 5, and the communication between the first conductive piece 7 and the second conductive piece 8 is completed, so that the electrochemical mechanical polishing process performed when the wafer is fixed by adsorption is realized.
The pressure of mechanical polishing is low and the deformation of the wafer 6 to be processed is small because of the electrochemical corrosion of the surface metal of the wafer 6 to be processed; the electrolyte does not contain an oxidant, so that the pollution to the environment is small; meanwhile, the accuracy of process control can be improved by accurately detecting the electrochemical polishing endpoint. Therefore, compared with the traditional polishing process, the electrochemical mechanical polishing process can simultaneously give consideration to three key indexes of low polishing pressure, high polishing efficiency and small environmental pollution, and has great development space in the novel polishing process.
As shown in fig. 5, the first conductive member 7 is a cathode metal ring, the cathode metal ring may have multiple groups of partitions, for example, may have 5 partitions, for providing different partition voltages, adjusting polishing rate of the wafer in a diameter direction, improving polishing flatness of the wafer in the diameter direction, having a gap of 1-2mm between each partition, preventing electrical contact between each partition, and avoiding uneven electrochemical corrosion caused by excessive gap, each partition is provided with a cathode contact 21, the cathode contact 21 is connected with a power supply negative electrode through a wire, and forms a closed loop with the second conductive member 8 under an electrolyte electrical connection effect, so as to complete an electrochemical polishing process of the wafer, and in a path between the power supply and the first conductive member 7, or in a path between the power supply and the second conductive member 8, an electric meter is provided for detecting electric quantity or current, so as to obtain an electrochemical polishing endpoint, and further, an electrochemical polishing progress can be accurately controlled.
As shown in fig. 1, a supporting table 22 is arranged below the polishing table 1, the polishing table 1 is rotatably connected with the supporting table 22 through a bearing, a baffle 23 is arranged around the supporting table 22, the baffle 23 and the supporting table 22 form a containing cavity, a liquid leakage hole 24 is formed in the bottom of the supporting table 22, and electrolyte on the polishing pad 2 flows into the containing cavity in the rotation process of the polishing pad 2 after reacting, and then flows out of the liquid leakage hole 24.
As shown in fig. 1, the electrochemical mechanical polishing device for silicon carbide wafers further comprises a recovery unit 25, a filtering unit 26 and a storage unit 27, wherein the electrolyte flowing out of the liquid leakage hole 24 is sequentially sent into the spraying device 20 after passing through the recovery unit 25, the filtering unit 26 and the storage unit 27, a first flow control unit 28 and a temperature control unit 29 are arranged between the storage unit 27 and the spraying device 20, impurities in the electrolyte recovered in the recovery unit 25 are removed by the filtering unit 26, the purified electrolyte enters the storage unit 27 for recycling, the flow and the temperature of the electrolyte entering the spraying device 20 are controlled by the first flow control unit 28 and the temperature control unit 29 as required, the temperature of the electrolyte is controlled at 10-50 ℃, the flow of the electrolyte is controlled as required, and the heated electrolyte is transmitted to a spray head through a conveying pipeline and flows to the surface of the wafer through a nozzle for participation in electrochemical reaction.
As shown in fig. 1, the electrochemical mechanical polishing device for silicon carbide wafer further comprises a cleaning unit 30, the cleaning unit 30 is connected with the spraying device 20, a second flow control unit 31 is arranged between the cleaning unit 30 and the spraying device 20, the cleaning unit 30 is used for storing deionized water, after the electrochemical mechanical polishing process is completed, the deionized water is used for cleaning electrolyte and impurities remained on the polishing pad 2, and the second flow control unit 31 is used for controlling the flow of the deionized water.
As shown in fig. 2, in the electrochemical mechanical polishing apparatus for silicon carbide wafers provided in this embodiment, the polishing head 4 has fixing members 9 extending downward around the adsorption balloon 5 to fix the wafer 6 to be processed; the bottom of the fixing piece 9 is provided with a diversion trench 10. The fixing piece 9 prevents the wafer 6 to be processed from sliding sheets under stress in the moving polishing process, so that the polishing effect is affected; the diversion trench 10 is used for guiding the electrolyte to flow in and out, so that the electrolyte contacts the wafer to be processed more uniformly, and the rapid discharge of the electrolyte is facilitated. The fixing piece 9 is of an annular structure, the diversion trenches 10 are provided with a plurality of groups, the diversion trenches 10 are uniformly distributed in the circumferential direction of the fixing piece 9, and the diversion trenches 10 are obliquely arranged and can be inclined clockwise from inside to outside to conform to the flowing direction of electrolyte.
As shown in fig. 2 and 3, the polishing head 4 further includes a porous plate 11 and an air path 13, the porous plate 11 is disposed at the bottom of the polishing head 4, and the porous plate 11 is provided with a via hole 12; the adsorption air bag 5 is coated and arranged at the bottom of the porous plate 11; the air channel 13 is disposed inside the polishing head 4, and the air channel 13 is communicated with the via hole 12, and is used for controlling the expansion and contraction of the adsorption air bag 5. The porous plate 11 and the through holes 12 on the porous plate provide support for the adsorption air bag 5 in the shrinkage process, so that the wafer 6 to be processed is stable in the adsorption transfer process.
As shown in fig. 2, in the electrochemical mechanical polishing apparatus for silicon carbide wafer provided in this embodiment, the second conductive member 8 is disposed at the edge of the adsorption balloon 5. When the wafer 6 to be processed is adsorbed, only the edge portion of the wafer 6 to be processed is required to be contacted with the second conductive member 8, so that too much contact can affect the adsorption fixing process of the wafer, and the surface of the wafer is easily damaged. The second conductive member 8 may have a circular ring structure, and in addition, as an alternative embodiment, the second conductive member 8 may have a partial circular ring structure or a rectangular structure.
As shown in fig. 2, in the electrochemical mechanical polishing apparatus for silicon carbide wafer provided in this embodiment, the second conductive member 8 has at least two groups of output points, and the output points are all disposed at the edge of the adsorption balloon 5. The electrochemical process can be realized by the electric connection of any output point, and when one of the output points is disconnected accidentally in the moving process, the electrochemical process can be continuously performed by the arrangement of other output points. In addition, as an alternative embodiment, the second conductive member 8 may also have a set of output points, where the second conductive member 8 has a larger contact range with the wafer 6 to be processed, and the set of output points may also achieve stable electrical connection.
In the electrochemical mechanical polishing device for silicon carbide wafers provided in this embodiment, the second conductive member 8 is double-sided conductive foil paper, and the double-sided conductive foil paper is double-conductive aluminum foil paper or double-conductive tin foil paper. Not only has excellent conductive performance, is soft and thin, but also is well suitable for the shrinkage of the adsorption air bag 5, and the thickness of the adsorption air bag can not influence the adsorption of the wafer 6 to be processed, thereby having better effect. The double-sided conductive foil paper is adopted, one sticky surface is adhered to the air bag, the lead can be fixed, and the other surface is used for contacting with the wafer to be processed.
As shown in fig. 2 to 4, in the electrochemical mechanical polishing device for silicon carbide wafers provided in this embodiment, the polishing head 4 is provided with an electrically conductive slip ring 14, and the second electrically conductive member 8 is electrically connected with the electrically conductive slip ring 14 through a wire 16. In the process of rotating the polishing head 4, the conductive slip ring 14 can avoid the problem of winding of the wire 16, and the existence of the conductive slip ring 14 can greatly simplify the system structure and avoid damage to the wire 16 in the rotating process.
As shown in fig. 2, in the electrochemical mechanical polishing device for silicon carbide wafer provided in this embodiment, the polishing head 4 is provided with a wire via hole 15, and the wire 16 passing through the wire via hole 15 connects the conductive slip ring 14 and the second conductive member 8, so as to avoid abrasion of the wire during polishing and influence on implementation of the electrochemical process. The wire via 15 is provided in the holder 9, and the shortest path that the wire 16 will take during connection can be selected.
As shown in fig. 1, the electrochemical mechanical polishing device for silicon carbide wafers provided in this embodiment further includes a first driving component 17 and a second driving component 18, where an output end of the first driving component 17 is connected to the polishing head 4 to drive the polishing head 4 to move; the output end of the second driving assembly 18 is connected with the polishing head 4 to drive the polishing head 4 to rotate. One side of the polishing device is provided with a base, the top of the base is provided with a swing arm, a first driving assembly 17 is arranged on the swing arm, the first driving assembly 17 can be a linear module, a second driving assembly 18 is arranged on the output end of the first driving assembly 17, the second driving assembly 18 can be a rotating motor, and the rotation and the translation of the polishing head 4 are realized in the polishing process.
As shown in fig. 1, the electrochemical mechanical polishing device for silicon carbide wafers provided in this embodiment further includes a third driving assembly 19, where an output end of the third driving assembly 19 is connected to the polishing table 1 to drive the polishing table 1 to rotate, the third driving assembly 19 is disposed below the supporting table 22, and an output end of the third driving assembly 19 passes through the supporting table 22 and is fixedly connected with the polishing table 1 coaxially, and the third driving assembly 19 may be directly driven by a rotating motor or may be driven by a motor to the polishing table 1 through a belt and a transmission shaft. The polishing head 4 performs a rotational motion and a reciprocating motion, and cooperates with the rotating polishing pad 2, thereby realizing efficient polishing of the wafer 6 to be processed.
As shown in fig. 1, the electrochemical mechanical polishing device for silicon carbide wafers provided in this embodiment further includes a spraying device 20, where the spraying device 20 is disposed above the polishing table 1 and is used for spraying electrolyte to the polishing pad 2, the spraying device 20 includes a nozzle and a nozzle, the nozzle faces the polishing pad 2, the polishing pad 2 is not required to be soaked, the electrolyte is saved, the electrolyte can be sprayed and suspended according to actual situations, and the electrochemical mechanical polishing process can be better controlled.
The wafer 6 to be processed is contacted with the polishing pad 2 under the pressure of less than 1psi (pounds per square inch), and is matched with electrolyte with abrasive, and the mechanical polishing process is completed under the action of mechanical rotation and reciprocating motion, the polishing rotating speed is 0-200rpm, and the further polishing rotating speed is 0-90rpm.
As shown in fig. 2 and 3, the process of adsorbing the wafer 6 to be processed by the polishing head 4 is as follows: the polishing head 4 is moved to the position above the carrying platform carrying the wafer 6 to be processed, the air channel 13 is filled with air, the adsorption air bag 5 is in an expansion and unfolding state under the action of air pressure (nitrogen), the polishing head 4 is gradually contacted with the surface of the wafer 6 to be processed, the air channel 13 is discharged after the adsorption air bag 5 is contacted with the wafer, the adsorption air bag 5 is in a shrinkage state under the action of air pressure, at the moment, a vacuum negative pressure area is formed between the wafer 6 to be processed and the adsorption air bag 5, the wafer 6 to be processed is tightly pressed on the adsorption air bag 5 under the action of negative pressure, meanwhile, the two sides of the wafer 6 to be processed are tightly pressed on the second conductive piece 8 under the action of negative pressure, and the polishing head 4 is adsorbed on the wafer 6 to be processed under the action of mechanical vertical movement to be separated from the carrying platform.
As shown in fig. 4, the planarization process of the wafer 6 to be processed is: the polishing head 4 moves to the upper part of the polishing table 1 and acts on the polishing pad 2, the air channel 13 is used for air inflow, the adsorption air bag 5 compresses the wafer 6 to be processed under the action of air pressure, two sides of the wafer 6 to be processed compress the second conductive piece 8, the second conductive piece 8 extends outwards and is connected with a wire, the wire passes through the wire through hole 15 and is connected to the conductive slip ring 14 above the polishing head 4, the conductive slip ring 14 is connected with the positive electrode of a power supply, the first conductive piece 7 is electrically connected with the negative electrode of the power supply, at the moment, the wafer 6 to be processed realizes electrochemical corrosion under the condition of electric power, and the wafer 6 to be processed rotates and reciprocates under the drive to realize mechanical planarization.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (11)

1. An electrochemical mechanical polishing apparatus for silicon carbide wafers, comprising:
a polishing table (1) on which a polishing pad (2) is provided, the polishing pad (2) having a liquid passing hole (3);
the polishing head (4) is arranged above the polishing table (1), an adsorption air bag (5) is arranged on the polishing head (4), and the adsorption air bag (5) is used for adsorbing a wafer (6) to be treated and applying acting force to the wafer (6) to be treated;
the electrode assembly comprises a first conductive piece (7) and a second conductive piece (8), wherein the first conductive piece (7) is arranged below the polishing pad (2), the second conductive piece (8) is a sheet-shaped conductive body, and the second conductive piece (8) is arranged on the adsorption air bag (5); when the wafer (6) to be processed is adsorbed, a part of the wafer (6) to be processed is connected with the second conductive piece (8), and when the wafer (6) to be processed is polished, the wafer (6) to be processed is electrically connected with the first conductive piece (7) through electrolyte in the liquid passing hole (3).
2. Electrochemical mechanical polishing device for silicon carbide wafers according to claim 1, characterized in that the polishing head (4) has a fixing member (9) extending downward at the periphery of the suction bladder (5) to fix the wafer (6) to be processed; the bottom of the fixing piece (9) is provided with a diversion trench (10).
3. The silicon carbide wafer electrochemical mechanical polishing apparatus of claim 1, wherein the polishing head (4) further comprises:
a porous plate (11) arranged at the bottom of the polishing head (4), wherein a via hole (12) is arranged on the porous plate (11); the adsorption air bag (5) is coated and arranged at the bottom of the porous plate (11);
the gas path channel (13) is arranged inside the polishing head (4), and the gas path channel (13) is communicated with the through hole (12) and is used for controlling the expansion and contraction of the adsorption air bag (5).
4. Electrochemical mechanical polishing device for silicon carbide wafers according to claim 1, characterized in that the second conductive element (8) is arranged at the edge of the adsorption balloon (5).
5. Electrochemical mechanical polishing device for silicon carbide wafers according to claim 4, characterized in that the second conductive element (8) has at least two sets of output points, which are all arranged at the edge of the adsorption balloon (5).
6. The electrochemical mechanical polishing apparatus of silicon carbide wafers as set forth in claim 1 wherein the second conductive member (8) is a double-sided conductive foil paper, which is a double-sided aluminum foil paper or a double-sided tin foil paper.
7. Electrochemical mechanical polishing device for silicon carbide wafers according to any one of claims 1 to 6, characterized in that an electrically conductive slip ring (14) is provided on the polishing head (4), the second electrically conductive member (8) being electrically connected to the electrically conductive slip ring (14) by means of a wire (16).
8. Electrochemical mechanical polishing device for silicon carbide wafers according to claim 7, characterized in that the polishing head (4) is provided with wire vias (15), wires (16) passing through the wire vias (15) connecting the conductive slip ring (14) and the second conductive member (8).
9. The silicon carbide wafer electrochemical mechanical polishing device according to any one of claims 1 to 6, further comprising:
a first driving assembly (17) with an output end connected with the polishing head (4) to drive the polishing head (4) to move;
and the output end of the second driving component (18) is connected with the polishing head (4) so as to drive the polishing head (4) to rotate.
10. The silicon carbide wafer electrochemical mechanical polishing device according to any one of claims 1 to 6, further comprising:
and the output end of the third driving component (19) is connected with the polishing table (1) so as to drive the polishing table (1) to rotate.
11. The silicon carbide wafer electrochemical mechanical polishing device according to any one of claims 1 to 6, further comprising:
and the spraying device (20) is arranged above the polishing table (1) and is used for spraying electrolyte to the polishing pad (2).
CN202311001576.5A 2023-08-09 2023-08-09 Electrochemical mechanical polishing device for silicon carbide wafer Pending CN117020926A (en)

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CN202311001576.5A CN117020926A (en) 2023-08-09 2023-08-09 Electrochemical mechanical polishing device for silicon carbide wafer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311001576.5A CN117020926A (en) 2023-08-09 2023-08-09 Electrochemical mechanical polishing device for silicon carbide wafer

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CN117020926A true CN117020926A (en) 2023-11-10

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