CN113889394B - SiC semiconductor dry surface treatment equipment and method - Google Patents
SiC semiconductor dry surface treatment equipment and method Download PDFInfo
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- CN113889394B CN113889394B CN202111124843.9A CN202111124843A CN113889394B CN 113889394 B CN113889394 B CN 113889394B CN 202111124843 A CN202111124843 A CN 202111124843A CN 113889394 B CN113889394 B CN 113889394B
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- H—ELECTRICITY
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- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32192—Microwave generated discharge
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/3244—Gas supply means
- H01J37/32449—Gas control, e.g. control of the gas flow
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/32458—Vessel
- H01J37/32477—Vessel characterised by the means for protecting vessels or internal parts, e.g. coatings
- H01J37/32495—Means for protecting the vessel against plasma
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32917—Plasma diagnostics
- H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge
- H01J37/32981—Gas analysis
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- 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/0445—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide
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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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/0445—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide
- H01L21/045—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide passivating silicon carbide surfaces
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- 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
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/335—Cleaning
Abstract
The invention belongs to the technical field of semiconductor surface cleaning and passivation, and relates to SiC semiconductor dry method surface treatment equipment and a method, wherein the treatment equipment comprises a double ECR plasma supply device, a vacuum reaction chamber, a sample loading chamber, a residual gas analyzer, a gas distribution device and a gas distribution system. The processing method comprises the following steps: the method comprises the steps of (1) vacuumizing a sample loading chamber, (2) vacuumizing a vacuum reaction chamber, (3) cleaning the surface of a SiC wafer, (4) passivating the surface of the SiC wafer, and (5) finishing the surface treatment of the SiC wafer. The invention adopts the double ECR plasma sources as the plasma generating device, adjusts the coverage area of the plasma by changing the included angle of the central axes of the two ECR plasma sources, meets the dry cleaning requirement of the 6-inch SiC wafer, and improves the defects of small size of a plasma uniform area and low plasma density generated by a single ECR plasma source.
Description
Technical Field
The invention relates to a SiC semiconductor dry surface treatment device and method, belonging to the technical field of semiconductor surface cleaning and passivation.
Background
SiC (silicon carbide) is one of wide bandgap semiconductor hot spot materials, has the advantages of high critical breakdown electric field, high thermal conductivity and the like, and has important application in the field of high-voltage and high-temperature resistant power devices. SiC is also a preferable substrate for epitaxially growing graphene, gallium nitride, and the like.
From the field of semiconductor surface microstructures and defects, the surface of an SiC semiconductor still has outstanding new problems of carbon residue, silicon dangling bonds, ion pollution, surface pollution and the like after the SiC semiconductor is cleaned by a traditional wet method, and on one hand, the defects on the surface can exist on the interface of a device in the form of interface defects or fixed charges to capture or emit electrons, so that the threshold voltage drift and the reliability of the device are influenced; on the other hand, the defect state of the SiC surface affects the contact characteristics between the metal and the semiconductor, thereby affecting the performance of the SiC device, such as efficiency and switching speed. Moreover, the atomic structure and morphology of the surface of SiC directly determine the crystal structure and film quality of the epitaxially grown material.
For the technical scheme disclosed at present, liu Bingbing et al [ application number: 201510735852.X ] propose that by adopting ECR microwave plasma system to generate hydrogen-nitrogen mixed plasma to clean the SiC surface, the surface state density can be obviously reduced, the generation of interface defect state in the oxidation process is effectively inhibited, and the breakdown characteristic of an oxide film is improved.
Although the prior apparatus and method described provide technical support for SiC surface treatment, the apparatus and method also suffer from the following disadvantages: the coverage area of the plasma generated by a single plasma source is limited, the density of the edge of the plasma source is low, and the surface treatment effect cannot meet the requirement of surface treatment of SiC wafers with the size of 6 inches or more at present; the metal on the inner wall of the device is easy to be bombarded by plasma, the surface of the SiC wafer can be polluted by the generated metal ions, and the metal ions exist in the device in the form of movable ions, so that the performance of the device is seriously influenced; the gas used in the surface treatment process cannot be accurately regulated and controlled, and the phenomenon that the surface of the SiC wafer is damaged by plasma easily occurs, so that the arrangement and the structure of atoms on the surface of the SiC wafer are influenced.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a SiC semiconductor dry surface treatment device and a method. The method can be single dry surface cleaning, and can also be dry surface cleaning followed by dry surface passivation treatment so as to adapt to the requirements of ohmic contact process of SiC devices and the early-stage surface treatment of gate oxide layer preparation process. According to the invention, the double ECR plasma sources are used as the plasma generating device, the coverage area of the plasma is adjusted by changing the included angle of the central axes of the two ECR sources, the dry surface treatment requirement of the 6-inch SiC wafer can be met, and the defects of small size and low plasma density of a plasma uniform area generated by a single plasma source are improved by mutually overlapping the edge plasmas of the double ECR plasma sources; the aluminum foil hanging piece with a passivation coating covers the metal inner wall of the vacuum reaction chamber, and the shielding barrel made of quartz or borosilicate glass is arranged around the sample table, so that the purpose of shielding the bombardment of plasma on the metal wall is realized, and the pollution of metal particles on the SiC surface is reduced; the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel generate trace nitrogen and boron elements after plasma bombardment, and the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel have the advantages of convenience in replacement, low price and the like. In addition, the equipment provided by the invention is also provided with a residual gas analyzer, and the gas flow and the component proportion in the surface treatment process are accurately regulated and controlled in situ by monitoring the gas components in the vacuum reaction chamber in real time, so that the optimal surface treatment effect is achieved.
In order to achieve the above purpose and solve the problems existing in the prior art, the invention adopts the technical scheme that: a processing method of SiC semiconductor dry surface processing equipment comprises a double ECR plasma supply device, a vacuum reaction chamber, a sample loading chamber, a residual gas analyzer, a gas distribution device and a gas distribution system, wherein 1 st and 2 nd ECR plasma sources, a microwave source and a waveguide tube with the same size are arranged above the vacuum reaction chamber, and the waveguide tube is provided with 1 st and 2 nd microwave coupling antennas to form the double ECR plasma supply device; the top of the vacuum reaction chamber is provided with a Faraday cylinder, an air inlet, a 1 st vacuum degree meter, an electronic probe and a 1 st halogen tungsten lamp, and a sample table with an electric heating device is arranged in the vacuum reaction chamber, wherein the electronic probe is used for accurately measuring and controlling the electron density and temperature of ECR plasma of the sample table, and the Faraday cylinder is used for accurately measuring and controlling the ion density and temperature of the ECR plasma of the sample table; the interface flanges of the 1 st and 2 nd ECR plasma sources are fixed on the corrugated pipe, the included angles of the central axes of the 1 st and 2 nd ECR plasma sources can be adjusted between 0 and 45 degrees, the axes of the 1 st and 2 nd ECR plasma sources face the center of the sample stage when the included angles of the central axes are 45 degrees, high-quality cleaning of wafers with different sizes is met by adjusting the included angles of the central axes, in addition, the bottom of the vacuum reaction chamber is connected with a vacuumizing device through a pipeline, the vacuum reaction chamber is also provided with a CCD (charge coupled device) imaging system, a magnetic manipulator, an observation window and a reflection high-energy electron diffractometer, the surface of the metal inner wall of the vacuum reaction chamber is fully distributed with a coating, a shielding barrel is arranged around the sample stage, the diameter of the shielding barrel is 180-240mm and the height is 50-120mm, and the material of the shielding barrel is selected from one of quartz or borosilicate glass; the thickness of the aluminum foil with the coating is 10-100 mu m, the surfaces of the two sides of the aluminum foil are covered with aluminum oxide films with the thickness of 5-20nm, the surface of the aluminum oxide is covered with the coating, the thickness of the coating is 0.5-2 mu m, and the coating is selected from one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film and a boron nitride film or the combination of the silicon oxide film, the silicon nitride film, the silicon oxynitride film and the boron nitride film; a quartz or borosilicate glass shielding barrel is arranged around the sample table and is used for shielding bombardment of plasma on the wall of a metal vessel so as to reduce pollution of metal ions on the surface of SiC, and trace nitrogen and boron elements generated by the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel after bombardment of the plasma also have beneficial effects on passivating defects on the surface of SiC; the sample loading chamber is arranged on the right side of the vacuum reaction chamber, the middle of the sample loading chamber is connected with the vacuum reaction chamber through a gate valve, and the sample loading chamber is provided with a 2 nd tungsten halogen lamp, a 2 nd vacuum degree gauge and a deflation valve; the gas distribution system comprises a 1 st quartz cup and a 2 nd quartz cup which are arranged in the 1 st ECR plasma source and the 2 nd ECR plasma source, wherein gas inlets are respectively connected with gas supply loop pipelines in the 1 st quartz cup and the 2 nd quartz cup and participate in microwave plasma discharge; the gas distribution device comprises a residual gas analyzer arranged on one side of the vacuum reaction chamber and connected with a computer information acquisition controller, wherein the computer information acquisition controller is also respectively connected with 6-path gas flow controllers, 6-path gas sources are respectively connected with the input ends of the 6-path gas flow controllers through 6 pressure reducing valves, the output ends of the 6-path gas flow controllers are connected with the input end of a gas mixing chamber, and the output end of the gas mixing chamber is connected with a gas inlet through a vacuum stop valve;
the processing method comprises the following steps:
step 1, vacuumizing a sample loading chamber, putting a sample into the sample loading chamber, starting a vacuumizing device to vacuumize the sample loading chamber to 10 DEG -4 -10 -7 Pa, opening a gate valve between the sample loading chamber and the vacuum reaction chamber, conveying the sample to a sample table of the vacuum reaction chamber, and closing the gate valve;
step 2, vacuumizing the vacuum reaction chamber, starting a vacuumizing device, and vacuumizing the vacuum reaction chamber to enable the vacuum degree to reach 10 -5 -10 -7 Pa；
and 5, finishing the surface treatment of the SiC wafer, and taking out the sample after the temperature is reduced to the room temperature after the surface treatment of the SiC wafer is finished.
The invention has the beneficial effects that: the processing equipment comprises a double ECR plasma supply device, a vacuum reaction chamber, a sample loading chamber, a residual gas analyzer, a gas distribution device and a gas distribution system. The processing method comprises the following steps: the method comprises the following steps of (1) vacuumizing a sample loading chamber, (2) vacuumizing a vacuum reaction chamber, (3) cleaning the surface of a SiC wafer, (4) passivating the surface of the SiC wafer, and (5) finishing the surface treatment of the SiC wafer. Compared with the prior art, the double ECR plasma sources are adopted as the plasma generating device, the coverage area of the plasma is adjusted by changing the included angle of the central axes of the two ECR sources, the dry cleaning requirement of the 6-inch SiC wafer can be met, and the defects of small size and low plasma density of a plasma uniform area generated by a single plasma source are improved by mutually overlapping the edge plasmas of the double ECR plasma sources; the aluminum foil hanging piece with a passivation coating is covered on the metal inner wall of the vacuum reaction chamber, and the shielding barrel made of quartz or borosilicate glass is arranged around the sample table, so that the purpose of shielding the bombardment of plasma on the metal wall is achieved, and the pollution of metal particles on the SiC surface is reduced; the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel generate trace nitrogen and boron elements after plasma bombardment, and the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel have the advantages of convenience in replacement, low price and the like. In addition, the equipment provided by the invention is also provided with a residual gas analyzer, and the gas flow and the component distribution ratio in the surface treatment process are accurately regulated and controlled in situ by monitoring the gas components in the vacuum reaction chamber in real time, so that the optimal surface treatment effect is achieved.
Drawings
FIG. 1 is a plan view of an apparatus for dry surface treatment of SiC semiconductor of the present invention.
In the figure: 1. a microwave source, 2, a vacuum reaction chamber, 2a, a Faraday cylinder, 2b, an air inlet, 2c, a 1 st vacuum degree meter, 2d, an electronic probe, 2e, a 1 st halogen tungsten lamp, 3, a waveguide tube, 3a, a 1 st microwave coupling antenna, 3b, a 2 nd microwave coupling antenna, 4, a 1 st ECR plasma source, 4a, a 2 nd ECR plasma source, 5, a 1 st quartz cup, 5a, a 2 nd quartz cup, 6, a sample loading chamber, 6a, a 2 nd halogen tungsten lamp, 6b, a 2 nd vacuum degree meter, 6c, an air release valve, 7, a gate valve, 8, a CCD imaging system, 9, a vacuumizing device, 10, a magnetic manipulator, 11, an observation window, 12, a residual gas analyzer, 13, a reflection high-energy electron diffractometer.
Fig. 2 is a cross-sectional view of fig. 1 with the dual ECR plasma sources of the invention positioned vertically.
In the figure: 14. the device comprises a corrugated pipe, 15 parts of a permanent magnet ring, 16 parts of an aluminum foil with a coating, 17 parts of a shielding barrel, 18 parts of a sample table, 19 parts of a heating device, 20 parts of a gas supply ring pipeline.
FIG. 3 is a cross-sectional view of FIG. 1 with the included angle of the central axis of the dual ECR plasma sources of the present invention disposed at 45 degrees.
Fig. 4 is a schematic view of the air distribution device of the present invention.
In the figure: 21. a gas mixing chamber 22, a vacuum stop valve 23, a computer information acquisition controller 24, a pressure reducing valve 25 and a gas flow controller (MFC).
FIG. 5 is a flow chart of the method steps of the present invention.
Detailed Description
The invention is further described with reference to the drawings and examples.
As shown in fig. 1, 2, 3 and 4, a SiC semiconductor dry surface treatment device comprises a dual ECR plasma supply device, a vacuum reaction chamber 2, a sample loading chamber 6, a residual gas analyzer 12, a gas distribution device and a gas distribution system, wherein 1 st and 2 nd ECR plasma sources 4 and 4a, a microwave source 1 and a waveguide 3 with the same size are arranged above the vacuum reaction chamber 2, and the waveguide 3 is provided with 1 st and 2 nd microwave coupling antennas 3a and 3b to form the dual ECR plasma supply device; a Faraday cylinder 2a, an air inlet 2b, a 1 st vacuum degree meter 2c, an electronic probe 2d and a 1 st halogen tungsten lamp 2e are arranged at the top of the vacuum reaction chamber 2, and a sample table 18 with a heating device 19 is arranged in the vacuum reaction chamber 2, wherein the electronic probe 2d is used for accurately measuring and controlling the electron density and the temperature of ECR plasma of the sample table 18, and the Faraday cylinder 2a is used for accurately measuring and controlling the ion density and the temperature of the ECR plasma of the sample table 18; the interface flanges of the 1 st and 2 nd ECR plasma sources 4 and 4a are fixed on a corrugated pipe 14, the included angles of the central axes of the 1 st and 2 nd ECR plasma sources can be adjusted between 0-45 degrees, the axes of the 1 st and 2 nd ECR plasma sources 4 and 4a face the center of a sample table 18 when the included angles of the central axes are 45 degrees, high-quality cleaning of wafers with different sizes is met by adjusting the included angles of the central axes, in addition, the bottom of a vacuum reaction chamber 2 is connected with a vacuumizing device 9 through a pipeline, the vacuum reaction chamber 2 is also provided with a CCD imaging system 8, a magnetic manipulator 10, an observation window 11 and a reflection high-energy electron diffractometer 13, the surface of the metal inner wall of the vacuum reaction chamber 2 is fully distributed with an aluminum foil 16 with a coating, a shielding barrel 17 is arranged around the sample table 18, the diameter of the shielding barrel 17 is 180-240mm and 50-120mm, and the material of the shielding barrel 17 is selected from quartz or acid glass; the thickness of the coated aluminum foil 16 is 10-100 μm, the surfaces on both sides are covered with 5-20nm aluminum oxide films, the surface of the aluminum oxide is covered with a coating, the thickness of the coating is 0.5-2 μm, and the coating is selected from one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film and a boron nitride film or the combination of the silicon oxide film, the silicon nitride film, the silicon oxynitride film and the boron nitride film; a quartz or borosilicate glass shielding barrel 17 is arranged around the sample table 18 and is used for shielding bombardment of plasma on the wall of a metal vessel so as to reduce pollution of metal ions on the surface of SiC, and trace nitrogen and boron elements generated by the aluminum foil with a passivation coating and the quartz or borosilicate glass shielding barrel 17 after bombardment of plasma also have beneficial effects on passivating defects on the surface of SiC; the sample loading chamber 6 is arranged on the right side of the vacuum reaction chamber 2, the middle of the sample loading chamber is connected with the vacuum reaction chamber 2 through a gate valve 7, and the sample loading chamber 6 is provided with a 2 nd halogen tungsten lamp 6a, a 2 nd vacuum gauge 6b and an air release valve 6c; the gas distribution system comprises 1 st and 2 nd quartz cups 5 and 5a arranged inside the 1 st and 2 nd ECR plasma sources 4 and 4a, and a gas inlet 2b is respectively connected with gas supply loop pipelines 20 in the 1 st and 2 nd quartz cups 5 and 5a to participate in microwave plasma discharge; the gas distribution device comprises a residual gas analyzer 12 which is arranged on one side of a vacuum reaction chamber 2 and connected with a computer information acquisition controller 23, wherein the computer information acquisition controller 23 is also respectively connected with 6 paths of gas flow controllers 25, 6 paths of gas sources are respectively connected with the input ends of the 6 paths of gas flow controllers 25 through 6 pressure reducing valves 24, the output ends of the 6 paths of gas flow controllers 25 are respectively connected with the input end of a gas mixing chamber 21, and the output end of the gas mixing chamber 21 is connected with a gas inlet 2b through a vacuum stop valve 22.
Example 1
The dry cleaning method for the 6-inch SiC wafer by adopting the equipment is adopted.
In this embodiment, both the two ECR plasma sources are vertically disposed, that is, an included angle θ between central axes of the two ECR plasma sources is 0 degree; the diameter of the quartz shielding barrel 17 arranged around the sample table 18 is 220mm, the height is 60mm, the surface of the metal inner wall of the vacuum reaction chamber 2 is fully distributed with an aluminum foil with a silicon oxide coating, the thickness of the aluminum foil is 50 μm, the aluminum oxide on the surfaces of two sides of the aluminum foil is 20nm, and the thickness of the silicon oxide coating on the surface of the aluminum oxide is 1.5 μm.
The cleaning steps are as follows:
step 1, putting a 6-inch SiC wafer into a sample loading chamber 6, starting a vacuumizing device 9, and vacuumizing the sample loading chamber 6 to 10 - 5 Pa, opening a gate valve 7 between the sample loading chamber 6 and the vacuum reaction chamber 2, then conveying the 6-inch SiC wafer onto a sample table 18 of the vacuum reaction chamber 2, and closing the gate valve 7;
step 2, starting a vacuumizing device 9, vacuumizing the vacuum reaction chamber 2 to make the vacuum degree reach 10 -6 Pa；
through the embodiment, the equipment for the semiconductor dry surface treatment provided by the invention can realize the dry cleaning of the SiC surface by regulating and controlling the shielding barrel 17, the coated aluminum foil 16 and the introduced gas components of the vacuum reaction chamber 2. When the included angle between the central axes of the 1 st and 2 nd ECR plasma sources 4 and 4a is 0 degree, the dry cleaning of the surface of the 6-inch SiC wafer can be finished, and the cleaning effect is remarkable.
Example 2
The dry cleaning method for the 4-inch SiC wafer by adopting the equipment is adopted.
In this embodiment, the included angle θ between the central axes of the two ECR plasma sources is 45 degrees, the diameter of the quartz shielding barrel disposed around the sample stage 18 is 200mm, the height thereof is 60mm, the surface of the metal inner wall of the vacuum reaction chamber 2 is fully covered with aluminum foil with a silicon oxide coating, the thickness of the aluminum foil is 50 μm, the aluminum oxide on the surfaces of both sides of the aluminum foil is 20nm, and the thickness of the silicon oxide coating on the surface of the aluminum oxide is 1.5 μm.
The cleaning procedure was the same as in example 1 except that the angle between the central axes of the 1 st and 2 nd ECR plasma sources 4 and 4a in step 3 was 45 degrees, and the cleaning time was 3min.
By using the method, the cleanliness of the surface of the cleaned SiC wafer is basically the same as that in the embodiment 1, and the reduction of the cleaning time indicates that when the included angle between the central axes of the two ECR plasma sources 4 and 4a is 45 degrees, the cleaning speed is improved to a certain extent because the plasmas covered by the middle area of the sample stage 18 are mutually overlapped to generate the plasmas with higher density, which indicates that the dry cleaning speed of the SiC semiconductor dry surface processing equipment provided by the invention for the sample with smaller size is higher, and the effect is not influenced.
Example 3
And (3) passivating the 6-inch SiC wafer after dry cleaning by adopting the equipment.
In this embodiment, both ECR plasma sources are placed vertically, that is, an included angle θ between central axes of the two ECR plasma sources is 0 degree; the diameter of a borosilicate glass shielding barrel arranged around the sample table 18 is 220mm, the height of the borosilicate glass shielding barrel is 60mm, the surface of the metal inner wall of the vacuum reaction chamber 2 is fully distributed with an aluminum foil with a silicon nitride coating, the thickness of the aluminum foil is 50 mu m, the aluminum oxide on the surfaces of two sides of the aluminum foil is 20nm, and the thickness of the silicon nitride coating on the surface of the aluminum oxide is 1.5 mu m.
The cleaning steps are as follows:
steps 1 to 3 are the same as in example 1 except that the quartz shield tub in the vacuum reaction chamber 2 was replaced with a borosilicate glass shield tub of the same size and the coating on both side surfaces of the aluminum foil was replaced with a silicon oxide film and a silicon nitride film.
wherein, the gas flow monitoring and controlling in step 4 is realized by a gas distribution device as shown in fig. 4. The gas components in the vacuum reaction chamber 2 are monitored by the residual gas analyzer 12, the monitoring results are fed back to the computer information acquisition controller 23, and finally the MFCs of each gas circuit are controlled in real time, so that in-situ accurate regulation and control of the gas components in the vacuum reaction chamber 2 are realized. Table 1 shows gas components and ratios corresponding to monitoring results at different cleaning times, and it can be found that the gas components in the vacuum reaction chamber 2 are substantially consistent within 5min of cleaning time, which proves the reliability and stability of the carried gas distribution system.
TABLE 1
The surface lattice arrangement and the roughness of the SiC wafer treated by the method are obviously improved, and the surface damage phenomenon caused by excessive cleaning of the plasma does not appear on the surface, which shows that the in-situ gas regulation and control system carrying the residual gas analyzer can realize accurate regulation and control of the gas proportion in the vacuum reaction chamber. The secondary ion mass spectrometry tests show that compared with a sample cleaned by the previous equipment, the SiC wafer surface treated by the equipment has obviously reduced quantity and types of surface metal ions, which proves that the aluminum foil with a passivation coating covered on the metal inner wall of the vacuum reaction chamber and the borosilicate glass shielding barrel arranged around the sample stage can effectively shield the bombardment of plasma on the metal wall and reduce the pollution of the metal ions on the SiC surface. Through calculation, the surface state density of the treated SiC wafer is obviously reduced, and the defect passivation effect is improved.
Example 4
The process in this example is the same as in example 3 except that the aluminum foil double-sided surface coating is replaced with a combination of silicon nitride and boron nitride coatings having a thickness of 2 μm.
The effect of passivating surface defects and roughness of the SiC wafer cleaned in example 4 were the same as those in example 3, and the density of surface states of the SiC wafers in examples 3 and 4 were calculated to be 5X 10 10 cm -2 eV -1 To 6X 10 10 cm -2 eV -1 . The surface roughness distribution of AFM test is between 0.2 and 0.26 nm. Examples 3 and 4 demonstrate that the replacement of the shielding barrel and the aluminum foil coating has little influence on the surface treatment result, and illustrate the stability and the reasonableness of the SiC semiconductor dry surface treatment equipment and the SiC semiconductor dry surface treatment method provided by the invention.
The invention has the advantages that: the invention provides SiC semiconductor dry surface treatment equipment and a method, wherein double ECR plasma sources are adopted as a plasma generating device, the coverage area of the plasma is adjusted by changing the included angle of the central axes of the two ECR sources, the dry surface treatment requirement of a 6-inch SiC wafer can be met, and the defects of small size and low plasma density of a plasma uniform region generated by a single plasma source are improved by mutually overlapping the edge plasmas of the double ECR plasma sources; the aluminum foil with a passivation coating is covered on the metal inner wall of the vacuum reaction chamber, and the shielding barrel made of quartz or borosilicate glass is arranged around the sample table, so that the purpose of shielding the bombardment of plasma on the metal wall is realized, and the pollution of metal particles on the SiC surface is reduced; the aluminum foil with the passivation coating and the quartz or borosilicate glass shielding barrel generate trace nitrogen and boron elements after plasma bombardment, and the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel have the advantages of convenience in replacement, low price and the like. In addition, the equipment provided by the invention is also provided with a residual gas analyzer, and the gas flow and the component distribution ratio in the passivation process are accurately regulated and controlled in situ by monitoring the gas components in the vacuum reaction chamber in real time, so that the optimal cleaning effect is achieved.
Claims (2)
1. The utility model provides a SiC semiconductor dry process surface treatment equipment, includes two ECR plasma supply device, vacuum reaction chamber, dress appearance room, residual gas analysis appearance, gas distribution device and gas distribution system, its characterized in that: the 1 st ECR plasma source, the 2 nd ECR plasma source, the microwave source and the waveguide tube which have the same size are arranged above the vacuum reaction chamber, and the waveguide tube is provided with the 1 st microwave coupling antenna and the 2 nd microwave coupling antenna which jointly form a double ECR plasma supply device; the top of the vacuum reaction chamber is provided with a Faraday cylinder, an air inlet, a 1 st vacuum degree meter, an electronic probe and a 1 st halogen tungsten lamp, and a sample table with an electric heating device is arranged in the vacuum reaction chamber, wherein the electronic probe is used for accurately measuring and controlling the electronic density and temperature of ECR plasma of the sample table, and the Faraday cylinder is used for accurately measuring and controlling the ion density and temperature of the ECR plasma of the sample table; the interface flanges of the 1 st and 2 nd ECR plasma sources are fixed on the corrugated pipe, the included angles of the central axes of the 1 st and 2 nd ECR plasma sources can be adjusted between 0 and 45 degrees, the axes of the 1 st and 2 nd ECR plasma sources face the center of the sample table when the included angles of the central axes are 45 degrees, high-quality cleaning of wafers with different sizes is met by adjusting the included angles of the central axes, in addition, the bottom of the vacuum reaction chamber is connected with a vacuumizing device through a pipeline, the vacuum reaction chamber is also provided with a CCD imaging system, a magnetic manipulator, an observation window and a reflection high-energy electron diffractometer, the surface of the metal inner wall of the vacuum reaction chamber is fully covered with a coated aluminum foil, a shielding barrel is arranged around the sample table, the diameter of the shielding barrel is 180-mm, the height is 50-120 zxft 5262, the material of the shielding barrel is selected from one of quartz or borosilicate glass, the coated aluminum foil is 10-100 mu m, the surfaces of the two sides of the aluminum foil are covered with an aluminum oxide film of 5-20 zxft 3763, the aluminum oxide film, the boron nitride film is covered with a combined thickness of 0.5 mu m, or a boron nitride film is covered with a silicon film combined silicon film of the boron nitride film; a quartz or borosilicate glass shielding barrel is arranged around the sample table and is used for shielding bombardment of plasma on the wall of a metal vessel so as to reduce pollution of metal ions on the surface of SiC, and trace nitrogen and boron elements generated by the aluminum foil pendant with the passivation coating and the quartz or borosilicate glass shielding barrel after bombardment of the plasma also have beneficial effects on passivating defects on the surface of SiC; the sample loading chamber is arranged on the right side of the vacuum reaction chamber, the middle of the sample loading chamber is connected with the vacuum reaction chamber through a gate valve, and the sample loading chamber is provided with a 2 nd halogen tungsten lamp, a 2 nd vacuum degree meter and an air release valve; the gas distribution system comprises a 1 st quartz cup and a 2 nd quartz cup which are arranged in the 1 st ECR plasma source and the 2 nd ECR plasma source, wherein gas inlets are respectively connected with gas supply loop pipelines in the 1 st quartz cup and the 2 nd quartz cup and participate in microwave plasma discharge; the gas distribution device comprises a residual gas analyzer which is arranged on one side of the vacuum reaction chamber and connected with a computer information acquisition controller, wherein the computer information acquisition controller is also respectively connected with 6 paths of gas flow controllers, 6 paths of gas sources are respectively connected with the input ends of the 6 paths of gas flow controllers through 6 pressure reducing valves, the output ends of the 6 paths of gas flow controllers are connected with the input end of a gas mixing chamber, and the output end of the gas mixing chamber is connected with a gas inlet through a vacuum stop valve.
2. A SiC semiconductor dry surface treatment method is characterized in that: the dry surface treatment of SiC semiconductors with the apparatus of claim 1, comprising the steps of:
step 1, vacuumizing a sample loading chamber, putting a sample into the sample loading chamber, starting a vacuumizing device to vacuumize the sample loading chamber to 10 DEG C -4 -10 -7 Pa, opening a gate valve between the sample loading chamber and the vacuum reaction chamber, conveying the sample to a sample table of the vacuum reaction chamber, and closing the gate valve;
step 2, vacuumizing the vacuum reaction chamber, starting a vacuumizing device, and vacuumizing the vacuum reaction chamber to enable the vacuum degree to reach 10 -5 -10 -7 Pa；
Step 3, cleaning the surface of the SiC wafer, setting the temperature of a sample platform to be 75-600 ℃, starting a gas distribution system when the temperature reaches the surface treatment temperature, introducing gas required for cleaning into the vacuum reaction chamber, wherein the introduced gas is argon or hydrogen, the gas flow is set to be 0-100sccm, adjusting the included angle of the central axes of the 1 st ECR and 2 nd ECR plasma sources to be 0-45 ℃, the microwave power is set to be 300-2000W, the air pressure in the vacuum reaction chamber 2 is adjusted to be 0.5-2Pa, the cleaning time is 1-20min, starting cleaning the surface of the SiC wafer, in the surface treatment process, a residual gas analyzer in the gas distribution system carries out real-time monitoring on each gas component in the vacuum reaction chamber, the monitoring result is fed back to a computer information acquisition controller, and then the gas flow controllers of each gas circuit are controlled to realize accurate regulation and control on the gas flow and the ratio in the vacuum reaction chamber;
step 4, passivating the surface of the SiC wafer, setting the temperature of a sample platform to be 75-600 ℃, when the temperature reaches the surface treatment temperature, introducing gas required for passivation into the vacuum reaction chamber, wherein the introduced gas is one of hydrogen, nitrogen, hydrogen chloride, chlorine and ammonia or a combination of hydrogen, nitrogen, hydrogen chloride, chlorine and ammonia, the gas flow of each gas path is set to be 0-100sccm, the included angle of central axes of the 1 st ECR and 2 nd ECR plasma sources is adjusted to be 0-45 ℃, the microwave power is set to be 300-2000W, the gas pressure in the vacuum reaction chamber is adjusted to be 0.5-2Pa, the passivation time is 1-20min, passivating the surface of the SiC wafer is started, in the surface treatment process, a residual gas analyzer in the gas distribution system monitors each gas component in the vacuum reaction chamber in real time, the monitoring result is fed back to an information acquisition controller, and then the gas flow controllers of each gas path are controlled to realize the regulation and control of the gas flow and proportioning in the vacuum reaction chamber accurately;
and 5, finishing the surface treatment of the SiC wafer, and taking out the sample after the temperature is reduced to the room temperature after the surface treatment of the SiC wafer is finished.
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| CN202111124843.9A CN113889394B (en) | 2021-09-25 | 2021-09-25 | SiC semiconductor dry surface treatment equipment and method |
| PCT/CN2021/136781 WO2023045101A1 (en) | 2021-09-25 | 2021-12-09 | Sic semiconductor dry surface treatment device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105304498A (en) * | 2015-10-15 | 2016-02-03 | 大连理工大学 | Method for reducing SiO2/SiC interface state density |
| CN105355561A (en) * | 2015-11-03 | 2016-02-24 | 大连理工大学 | Surface pretreatment method for reducing interface state density of SiC MOS |
| CN111527583A (en) * | 2017-12-27 | 2020-08-11 | 马特森技术有限公司 | Plasma processing apparatus and method |
| CN112863985A (en) * | 2019-11-12 | 2021-05-28 | 东京毅力科创株式会社 | Plasma processing apparatus |
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| JP5733623B2 (en) * | 2011-06-10 | 2015-06-10 | 国立大学法人九州大学 | Manufacturing method of semiconductor device |
| JP2019207912A (en) * | 2018-05-28 | 2019-12-05 | 東京エレクトロン株式会社 | Upper electrode assembly, processing apparatus, and manufacturing method of upper electrode assembly |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105304498A (en) * | 2015-10-15 | 2016-02-03 | 大连理工大学 | Method for reducing SiO2/SiC interface state density |
| CN105355561A (en) * | 2015-11-03 | 2016-02-24 | 大连理工大学 | Surface pretreatment method for reducing interface state density of SiC MOS |
| CN111527583A (en) * | 2017-12-27 | 2020-08-11 | 马特森技术有限公司 | Plasma processing apparatus and method |
| CN112863985A (en) * | 2019-11-12 | 2021-05-28 | 东京毅力科创株式会社 | Plasma processing apparatus |
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