CN116721915A - SiC etching method and equipment - Google Patents

SiC etching method and equipment Download PDF

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Publication number
CN116721915A
CN116721915A CN202310973991.0A CN202310973991A CN116721915A CN 116721915 A CN116721915 A CN 116721915A CN 202310973991 A CN202310973991 A CN 202310973991A CN 116721915 A CN116721915 A CN 116721915A
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etching
gas
controlling
preset
less
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CN116721915B (en
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林政勋
郭轲科
廖舜一
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Wuxi Yiwen Microelectronics Technology Co ltd
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Advanced Materials Technology and Engineering Inc
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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
    • H01L21/18—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 elements of Group IV of the Periodic System 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
    • H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
    • 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
    • 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
    • H01L21/18—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 elements of Group IV of the Periodic System 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
    • H01L21/3065—Plasma etching; Reactive-ion etching
    • H01L21/30655—Plasma etching; Reactive-ion etching comprising alternated and repeated etching and passivation steps, e.g. Bosch process
    • 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
    • H01L21/67—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
    • H01L21/67063—Apparatus for fluid treatment for etching
    • H01L21/67069—Apparatus for fluid treatment for etching for drying etching
    • 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
    • H01J2237/334—Etching
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention relates to the technical field of semiconductors, in particular to a SiC etching method and equipment, wherein the SiC etching method comprises the following steps: removing a crust layer at the bottom of the preset groove, and performing single-step etching or multi-step etching; a step of removing the crust layer at the bottom of the preset trench, comprising: by CF 4 Removing the hard shell layer at the bottom of the preset groove by gas; a single step etch or a multi-step etch step comprising: using main etching gas SF 6 And an auxiliary etching gas for etching the SiC substrate, wherein the auxiliary etching gas comprises CBr 4 Gas to generate SiBr 4 And the side wall of the groove etched on the SiC substrate is attached to strengthen the protection of the side wall and reduce the roughness of the side wall. The etching method can transfer patternsThe roughness of the side wall of the groove etched by the SiC substrate is reduced, meanwhile, the breakdown possibility of the gate oxide of the groove is reduced, and the reliability of the semiconductor device is further improved.

Description

SiC etching method and equipment
Technical Field
The invention relates to the technical field of semiconductors, in particular to a SiC etching method and equipment.
Background
The semiconductor material with wide forbidden band (Eg is more than or equal to 2.3 eV) represented by silicon carbide (SiC), gallium nitride (GaN), zinc oxide (ZnO), diamond and aluminum nitride (AlN) has wider forbidden band width, higher breakdown electric field, higher thermal conductivity, higher electron saturation rate and higher radiation resistance, is more suitable for manufacturing high-temperature, high-frequency, high-power and radiation-resistant devices, and can be widely applied to the fields of high-voltage, high-frequency, high-temperature, high reliability and the like, including radio frequency communication, radars, satellites, power management, automobile electrons, industrial power electrons and the like.
In the related art, silicon carbide is used as a semiconductor substrate and an epitaxial layer in a patterning process, and a soft mask and a hard mask are adopted, wherein the soft mask mainly refers to photoresist, organic glue or other resin, and the hard mask mainly comprises inorganic film layers such as silicon nitride, silicon oxide, silicon oxynitride and high doping type inorganic film layers (doping elements can be boron, phosphorus and the like) or metal film layers such as Cr, ni, cu or composite film layers of metal compounds. The dry etching and the wet etching are adopted in the patterning process, and the dry etching method has the characteristic of anisotropy for the prior process, so that the pattern can be better transferred onto the substrate or the epitaxial layer.
In dry etching, the etching gas used has fluorine or chlorine radicals, and the fluorine-based gas includes: SF (sulfur hexafluoride) 6 、CF 4 、CHF 3 、CH 2 F 3 、CHF 3 、C 4 F 8 、C 3 F 8 、NF 3 、CBrF 3 The chlorine-based gas includes: cl 2 、BCl 3 、CCl 4 The etching auxiliary gas includes: o (O) 2 、CO、Ar、He、N 2 . Silicon carbide has hardness inferior to that of diamond, and has strong polar bonds, requiring more fluorine or chlorine to react with during etching. However, for forming SiC Trench (Trench) by etching, the increase of the etching rate may also result in excessive etching of the Trench sidewall; thus, micro trench and surface roughness increase of the trench sidewall after silicon carbide etching are liable to cause gate oxide breakdown, electric field concentration at the bottom, and gate oxide breakdown willThe breakdown voltage of the device is reduced, and the reliability of the device is affected.
Disclosure of Invention
The invention aims at providing a SiC etching method and equipment, which can reduce the roughness of the side wall of a groove formed in a patterned etching process of a SiC substrate, reduce the possibility of breakdown of trench gate oxide and further improve the reliability of a semiconductor device.
Embodiments of the invention may be implemented as follows:
in a first aspect, the present invention provides a SiC etching method for etching a SiC substrate having a mask, the mask having a predetermined trench; the SiC etching method comprises the following steps: removing a crust layer at the bottom of the preset groove, and performing single-step etching or multi-step etching;
a step of removing the crust layer at the bottom of the preset trench, comprising: by CF 4 Removing the hard shell layer at the bottom of the preset groove by gas;
a single step etch or a multi-step etch step comprising: using main etching gas SF 6 And an auxiliary etching gas for etching the SiC substrate, wherein the auxiliary etching gas comprises CBr 4 Gas to generate SiBr 4 And adhering to the side wall of the groove etched on the SiC substrate.
In an alternative embodiment, the step of single step etching specifically includes: controlling the pressure of the chamber to be 5-60mtorr during etching, controlling the radio frequency power to be less than or equal to 2000w, and controlling the bias power to be less than or equal to 1000w;
controlling a main etching gas SF 6 The flow rate of (2) is less than or equal to 200sccm, CBr 4 The flow rate of the gas is less than or equal to 200sccm, and the auxiliary etching gas also comprises O 2 And Ar, O 2 The flow rate of Ar is less than or equal to 200sccm, and the flow rate of Ar is less than or equal to 500sccm; the temperature of the etching is controlled to be less than or equal to 100 ℃.
In an alternative embodiment, the etching time of the single step etching step is 350-370s.
In an alternative embodiment, the method further comprises a voltage stabilizing step between the step of removing the crust layer at the bottom of the preset groove and the step of single-step etching, wherein the voltage stabilizing step comprises the following steps:
under the conditions of set chamber pressure and set temperature, main etching gas SF is introduced into etching Cheng Qiangtong 6 And auxiliary etching gas for several seconds.
In an alternative embodiment, the chamber pressure is set to 5-60mtorr, and the temperature of the ESC electrostatic chuck is set to-20-100 ℃; main etching gas SF is introduced into etching system Cheng Qiangtong 6 And the duration of the auxiliary etching gas is 3-5s, and the auxiliary etching gas comprises CBr 4 、O 2 And Ar;
introducing main etching gas SF into etching cavity 6 When the flow is less than or equal to 200sccm, introducing CBr into the etching cavity 4 When the flow is less than or equal to 200sccm, introducing O into the etching cavity 2 The flow rate is less than or equal to 200sccm, and the flow rate when Ar is introduced into the etching cavity is less than or equal to 500sccm.
In an alternative embodiment, the step of multi-step etching includes at least a first etch and a second etch, wherein,
the first etching step specifically comprises the following steps: controlling etching pressure to be a first preset pressure, controlling radio frequency power to be a first preset radio frequency power, and controlling bias power to be a first preset bias power; main etching gas SF for controlling first etching 6 The flow rate of the auxiliary etching gas is less than or equal to 200sccm, and the auxiliary etching gas during the first etching also comprises O 2 And Ar, CBr for controlling the first etching 4 The flow rate of the first etching solution is less than or equal to 200sccm, and the O of the first etching solution is controlled 2 The flow rate of Ar in the first etching is controlled to be less than or equal to 200sccm; controlling the temperature of the first etching to be-20-100 ℃ and the time of the first etching to be 110-130s;
the second etching step specifically comprises the following steps: controlling etching pressure to be a second preset pressure, controlling radio frequency power to be a second preset radio frequency power, and controlling bias power to be a second preset bias power; main etching gas SF for controlling second etching 6 The flow rate of the auxiliary etching gas is less than or equal to 200sccm, and the auxiliary etching gas during the second etching also comprises O 2 And Ar, CBr for controlling the second etching 4 And controlling the flow rate of the second etching to be less than or equal to 200sccm 2 The flow rate of Ar in the second etching is controlled to be less than or equal to 200sccm; controlling the temperature of the second etching to be-20-100 ℃;
the first preset pressure is greater than the second preset pressure, the first preset radio frequency power is less than the second preset radio frequency power, and the first preset bias power is less than the second preset bias power.
In an alternative embodiment, the second preset pressure is 5-60mtorr, the second preset radio frequency power is less than or equal to 2000w, and the second preset bias power is less than or equal to 1000w; the second etching time is 170-190s.
In an alternative embodiment, CF is utilized 4 The step of removing the crust layer at the bottom of the preset groove by gas specifically comprises the following steps: controlling the pressure to be 5-60mtorr, controlling the radio frequency power to be less than or equal to 2000w, and controlling the CF 4 The gas flow rate of the gas is less than or equal to 200sccm, and the temperature is controlled to be-20-100 ℃.
In an alternative embodiment, CF is utilized 4 The time for removing the crust layer by the gas is 10-15s.
In a second aspect, the present invention provides a SiC etching apparatus for use in the SiC etching method of any one of the preceding claims; the SiC etching apparatus includes: the etching device comprises an etching device body and a gas heating device, wherein the etching device body is provided with an etching cavity, and the etching cavity is used for placing a silicon carbide wafer; the gas heating device is connected with the etching device body and communicated with the etching cavity through a gas pipe, and is used for fixing solid CBr 4 Sublimating into a gaseous state to cause CBr in the gaseous state 4 The etching solution is conveyed into an etching cavity through an air pipe to participate in etching reaction; the outside of the air pipe is wrapped with an insulating layer.
The SiC etching method and the SiC etching equipment have the beneficial effects that: the SiC etching equipment provided by the embodiment of the invention can carry out SiC etching; specifically, when etching the patterned SiC substrate, the main etching gas is SF 6 The auxiliary etching gas comprises CBr 4 Gas, SF 6 And CBr 4 Can generate SiBr by reaction 4 The adhesive is adhered to the side wall of the groove obtained by etching, so that the side wall of the groove can be protected, and the transverse etching in the etching process is reduced, so that the etching is reducedAnd after patterning, the roughness of the side wall of the SiC trench is reduced, the possibility of breakdown of trench gate oxide is reduced, and the reliability of the semiconductor device is further improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a structure of an SiC etching apparatus according to an embodiment of the present invention;
FIG. 2 is a topography diagram before etching of a substrate with a SiC trench depth of 1 μm, which is obtained by etching in example 1 of the present invention;
FIG. 3 is a topography of a substrate etched to a SiC trench depth of 1 μm in example 1 of the present invention;
FIG. 4 is a schematic diagram of the invention before etching to obtain a trench;
FIG. 5 is a schematic diagram of the present invention after etching to obtain a trench;
FIG. 6 is a topography diagram before etching a substrate with a SiC trench depth greater than 1 μm, which is obtained by etching in example 3 of the present invention;
FIG. 7 is a topography of a substrate etched to a SiC trench depth greater than 1 μm in example 3 of the present invention;
FIG. 8 is a topography of the substrate of comparative example 1 after etching in accordance with the present invention;
FIG. 9 is a topography of the substrate of comparative example 2 after etching in accordance with the present invention;
FIG. 10 is a topography of a substrate after etching in comparative example 3 of the present invention.
Icon: 010-SiC etching equipment; 100-etching the device body; 110-etching the cavity; 200-a gas heating device; 210-trachea.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 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.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
The embodiment provides a SiC etching method, which can be used for dry etching by using ICP inductively coupled plasma etching equipment and can be used for etching a SiC substrate with a mask, wherein the mask is provided with a preset groove; the SiC etching method comprises the following steps: removing a crust layer at the bottom of the preset groove, and performing single-step etching or multi-step etching; removing the preset grooveA step of forming a crust layer on the bottom of the trough, comprising: by CF 4 Removing the hard shell layer at the bottom of the preset groove by gas; a single step etch step or a multi-step etch step comprising: using main etching gas SF 6 And an auxiliary etching gas for carrying out patterned etching on the SiC substrate, wherein the auxiliary etching gas comprises CBr 4 Gas to generate SiBr 4 And the side wall of the groove is adhered to the SiC substrate and etched, so that transverse etching in the etching process is reduced.
When the patterned SiC substrate is etched, the main etching gas is SF 6 The auxiliary etching gas comprises CBr 4 Gas, SF 6 And CBr 4 Can generate SiBr by reaction 4 Attached to the side wall of the etched groove to generate SiBr 4 The method can protect the side wall of the groove, reduce transverse etching in the etching process, reduce the roughness of the side wall in the patterning etching process on the SiC substrate, reduce the possibility of breakdown of the gate oxide of the groove, and further improve the reliability of the semiconductor device.
It should be noted that, the mask on the SiC substrate may refer to a photoresist or a hard mask, where the mask mainly refers to a hard mask, for example: siO (SiO) 2 Mask, tiN mask, si 3 N 4 Masks, siNO masks, or other metal masks, etc.; the preset grooves arranged on the mask refer to grooves corresponding to patterns used for pattern transfer and arranged on the mask.
It should be further noted that the hard shell layer refers to: after exposure and development, a certain time is allowed to elapse from the etching process stage, and a cleaning process before etching is performed to form an oxide layer (SiO) of the SiC layer on the top of the mask layer and the bottom of the mask trench (preset trench) 2 ) Or a surface layer formed by evaporation of a solvent after development of the photoresist.
Optionally, utilize CF 4 A step of removing the crust layer at the bottom of the preset groove by gas, in particular removing SiO at the bottom of the preset groove 2 Layer, chemically reacted, CF 4 +SiO 2 →SiF 4 +CO 2 ，SiF 4 Is a volatile gas, and specifically comprises: controlled removal of oxide layerIs 5-60mtorr (e.g., 5mtorr, 10mtorr, 15mtorr, 20mtorr, 25mtorr, 30mtorr, 35mtorr, 40mtorr, 45mtorr, 50mtorr, 55mtorr, 60mtorr, etc.), controls the radio frequency power of the oxide layer removal to be less than or equal to 2000w (e.g., 100w, 200w, 300w, 400w, 500w, 600w, 700w, 800w, 900w, 1000w, 1100w, 1200w, 1300w, 1400w, 1500w, 1700w, 1800w, 1900w, 2000w, etc.), controls the CF when the oxide layer is removed 4 The gas flow rate of (a) is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 10sccm, etc.), and the temperature at the time of removing the oxide layer is controlled to be-20 to 100 ℃ (e.g., 20 ℃, -10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, etc.). SiO on the surface of SiC is firstly carried out 2 The oxide layer is removed, which is favorable for the subsequent smooth and reliable etching. It should be noted that the process parameters of the crust layer formed by evaporation of the solvent after developing the photoresist are similar to those described above.
In a preferred embodiment, the pressure for removing the crust is 10-40mtorr, the RF power for removing the crust is 100-1800w, CF when removing the crust 4 The gas flow rate of (2) is less than or equal to 180sccm, and the temperature at which the crust layer is removed is 60-80 ℃.
In the subsequent embodiment of obtaining the trench (SiC trecnh) by single-step etching, CF is removed when the crust layer is removed 4 May be less than or equal to 150sccm; in the subsequent embodiment of using multi-step etching to obtain trenches (SiC trench), CF is removed when the crust layer is removed 4 The gas flow rate of (2) may be 10-180sccm.
Further, the RF power 600w for removing the crust layer, CF when removing the crust layer 4 The gas flow rate of (2) is less than or equal to 100sccm, and the temperature at which the crust layer is removed is 60 ℃.
Optionally, utilize CF 4 Gas removal of SiO from SiC surface layer 2 The time of the crust layer is 10-15s, for example: 10s, 11s, 12s, 13s, 14s, 15s, etc. Will remove SiO 2 The time of the crust layer is controlled to be 10-15s, on one hand, the crust layer can be ensured to be reliably protectedRemoval to expose SiC facilitates subsequent etching, on the other hand, can control less removal of SiC under the crust layer when removing the crust layer of the SiC surface.
When the depth of the trench that the SiC substrate can etch is within 1 μm, i.e., the depth of the trench is less than or equal to 1 μm, a single step etching step may be employed.
Further, a voltage stabilizing step is performed between the step of removing the crust layer at the bottom of the preset groove and the step of single-step etching, and the voltage stabilizing step comprises the following steps: under the conditions of setting pressure and temperature of ESC electrostatic chuck, main etching gas SF is introduced into the etching cavity 6 And an auxiliary etching gas. Because the etching reaction cavity has larger volume, the gas can be fully distributed in the whole cavity in the step of stabilizing the pressure of the etching reaction cavity, the gas for etching is uniformly distributed, and the subsequent glow starting stabilization is also facilitated.
Optionally, in the pressure stabilizing step, the pressure is set to be 5-60mtorr (for example, 5mtorr, 10mtorr, 15mtorr, 20mtorr, 25mtorr, 30mtorr, 35mtorr, 40mtorr, 45mtorr, 50mtorr, 55mtorr, 60mtorr, etc.), and the temperature is set to be-20-100 ℃ (for example, -20 ℃, -10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, etc.); introducing main etching gas SF into etching cavity 6 And the duration of the auxiliary etching gas is 3-5s (such as 3s, 4s, 5s, etc.), the auxiliary etching gas comprises CBr 4 、O 2 And Ar; introducing main etching gas SF into etching cavity 6 The flow rate is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 10sccm, etc.), and CBr is introduced into the etching chamber 4 The flow rate is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 20sccm, 10sccm, etc.), and O is introduced into the etching chamber 2 The flow rate is 200sccm or less (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 10sccm, etc.), and the flow rate is 500sccm or less (e.g., 500sccm, 480sccm, 450sccm, 400sccm, 35 sccm) when Ar is introduced into the etching chamber0sccm, 300sccm, 250sccm, 200sccm, 150sccm, 100sccm, 80sccm, 30sccm, 20sccm, 10sccm, etc.).
In the pressure stabilizing step, the main etching gas and the auxiliary etching gas are uniformly mixed in a short time, so that the load effect of the etching patterning process is weakened, plasma is dissociated in a short time under the action of radio frequency power in the next step, and the great difference of the etching depths of grooves at different positions of the SiC device is caused by the fact that the partial distribution of the plasma is uneven and the reaction rate of the SiC substrate is different.
In a preferred embodiment, in the pressure stabilizing step, the pressure is set to be 10-40mtorr, and the temperature is set to be 60-80 ℃; introducing main etching gas SF into etching cavity 6 The flow rate is 20-150sccm, and CBr is introduced into the etching cavity 4 The flow rate is 20-180sccm, and O is introduced into the etching cavity 2 The flow rate is 10-100sccm, and the flow rate is 20-480sccm when Ar is introduced into the etching cavity.
Further, in the pressure stabilizing step, the pressure is set to be 20mtorr, and the temperature is set to be 60 ℃; introducing main etching gas SF into etching cavity 6 The flow rate is 30sccm, and CBr is introduced into the etching cavity 4 The flow rate is 100sccm, and O is introduced into the etching cavity 2 The flow rate was 50sccm, and the flow rate was 100sccm when Ar was introduced into the etching chamber.
The step of obtaining the groove by single step etching specifically comprises the following steps: controlling the etching pressure to be 5-60mtorr (e.g., 5mtorr, 10mtorr, 15mtorr, 20mtorr, 25mtorr, 30mtorr, 35mtorr, 40mtorr, 45mtorr, 50mtorr, 55mtorr, 60mtorr, etc.), controlling the radio frequency power (Source power) to be less than or equal to 2000w (e.g., 2000w, 1800w, 1600w, 1400w, 1300w, 1000w, 800w, 600w, 500w, 300w, 100w, 50w, 10w, etc.), and controlling the bias power (bias power) to be less than or equal to 1000w (e.g., 1000w, 800w, 600w, 500w, 400w, 350w, 300w, 250w, 200w, 100w, 50w, 10w, etc.). Controlling a main etching gas SF 6 The flow rate of (a) is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), CBr 4 The flow rate of the gas is less than or equal toAt 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), the auxiliary etching gas further includes O 2 And Ar, O 2 The flow rate of Ar is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and the flow rate of Ar is less than or equal to 500sccm (e.g., 500sccm, 480sccm, 450sccm, 400sccm, 350sccm, 300sccm, 250sccm, 200sccm, 150sccm, 100sccm, 80sccm, 30sccm, 20sccm, 10sccm, etc.); the temperature of the etching is controlled to be less than or equal to 100 ℃ (for example: 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ and the like).
In a preferred embodiment, in the step of single-step etching, the etching pressure is controlled to be 10-40mtorr, the radio frequency power is controlled to be 100-1800w, and the bias power is controlled to be 200-500w; controlling a main etching gas SF 6 The flow rate of the catalyst is 20-150sccm, CBr 4 The flow rate of the gas is 20-180sccm, and the auxiliary etching gas O 2 The flow rate of Ar is 20-480sccm and the flow rate of Ar is 10-180 sccm; the etching temperature is controlled to be 60-80 ℃.
Further, in the step of single-step etching, the radio frequency power is controlled to 1600w, and the bias power is controlled to 250w; controlling a main etching gas SF 6 Is 30sccm, CBr 4 The flow rate of the gas is 100sccm, and the auxiliary etching gas O 2 The flow rate of Ar is 50sccm, and the flow rate of Ar is 100sccm; the temperature of the etching was controlled to 60 ℃.
CBr 4 The material is in a white gray powder shape, has a relative molecular mass of 331.63, an alpha type melting point of 48.4 ℃, a beta type melting point of 90.1 ℃ and a boiling point of 189.7 ℃, can form a C-Br polar covalent bond when undergoing decomposition reaction, and has combustibility.
The present disclosure adds CBr in an auxiliary etching gas 4 And O 2 In combination with a main etching gas SF 6 Can etch silicon carbide with high efficiency and can react to generate SiBr 4 (reaction formula: CBr) 4 +SiC+SF 6 +O 2 →SiF 4 ↑+CO 2 ↑+SO 2 ↑+SiBr 4 ) And SiO 2 （2O 2 +SiC→SiO 2 +CO 2 ) And the adhesive is attached to the side wall of the etched groove to form side wall protection, so that transverse etching in the etching process is reduced, and the roughness of the etched groove is reduced.
In the related art, in silicon-based dry etching, HBr is used as a protective gas for the side wall of a trench to generate SiBr through the reaction of Br and Si 4 (reaction: 4 Br) - +Si 4+ =SiBr 4 ) The non-volatile substance is attached to the side wall of the groove to prevent F-radical or Cl-radical in the etching gas from further carrying out chemical reaction with Si to carry out transverse etching, thereby reducing the roughness of the side wall of the groove; however, the related art provides such a way that if used in SiO 2 On the substrate as a hard mask, H and SiO are formed 2 And F group (reaction formula: 4H) + +SiO 2 +4F - =SiF 4 +2H 2 O), resulting in the mask being consumed too fast, reducing the selectivity; in the method provided by the disclosure, CBr is added into auxiliary etching gas 4 And O 2 For SiO 2 CBr when used as a substrate for hard masks 4 With SiO 2 The weaker reaction does not result in the mask being consumed too quickly. Moreover, CBr employed by the present disclosure 4 The relative molecular weight is larger, and a deposition layer is more easily formed on the surface layer of the SiC groove. And is more beneficial to the protection of the side wall.
Optionally, when the etching depth is deeper, on the premise of requiring etching morphology, the plasma cannot detect the bottom of the groove under the action of small bias power, so that etching reaction is stopped, bias power is increased, the etching morphology meeting the requirement cannot be obtained, the lateral etching of the side wall of the groove is serious due to too high etching rate, further, the side wall roughness is high, enough deposition reaction is required to form side wall protection in the etching process, and the etching rate is not too high. Therefore, when the depth of the etched trench is smaller than 1 μm, the etching time for obtaining the trench (SiC Trecnh) by single-step etching is 350-370s, for example: 350s, 355s, 360s, 365s, 370s, etc. The etching depth can be controlled by adjusting the etching time, and the etching time is controlled to be 350-370s, so that the depth of the etched groove can be less than or equal to 1 mu m.
When the SiC substrate needs to be etched to obtain the groove with the depth larger than 1 mu m, a step of obtaining the groove (SiC Trecnh) by multi-step etching can be adopted, namely, on the premise of requiring etching morphology, the multi-step etching is adopted to reach the target depth.
Optionally, the step of obtaining the trench by multi-step etching at least includes a first etching and a second etching; the first etching step specifically includes: controlling etching pressure to be a first preset pressure, controlling radio frequency power to be a first preset radio frequency power, and controlling bias power to be a first preset bias power; main etching gas SF for controlling first etching 6 The auxiliary etching gas for the first etching further comprises O, and the flow rate of the auxiliary etching gas is less than or equal to 200sccm (for example, 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.) 2 And Ar, CBr for controlling the first etching 4 Is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and controlling the O of the first etch 2 The flow rate of Ar for the first etching is controlled to be 200sccm or less (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and the flow rate of Ar for the first etching is controlled to be 200sccm or less (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.); the temperature of the first etching is controlled to be-20-100 ℃ (for example, -20 ℃, -10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ and the like), the time of the first etching is controlled to be 110-130s (for example, 110s, 115s, 120s, 125s, 130s and the like), the etching depth is about 1.5 mu m, and under the same etching process parameters, the bottom Micro trench can be caused by continuously prolonging the time; the second etching step specifically comprises the following steps: controlling etching pressure to be a second preset pressure, controlling radio frequency power to be a second preset radio frequency power, and controlling bias power to be a second preset bias power; main etching for controlling second etchingGas SF 6 The flow rate of (a) is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and the auxiliary etching gas during the second etching further includes O 2 And Ar, CBr for controlling the second etching 4 Is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and controlling the O of the second etch 2 The flow rate of Ar controlling the second etching is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.), and the flow rate of Ar controlling the second etching is less than or equal to 200sccm (e.g., 200sccm, 180sccm, 150sccm, 130sccm, 100sccm, 80sccm, 70sccm, 50sccm, 30sccm, 20sccm, 10sccm, etc.); controlling the temperature of the second etching to be 0-100 ℃ (for example, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ and the like); the first preset pressure is greater than the second preset pressure, the first preset radio frequency power is less than the second preset radio frequency power, and the first preset bias power is less than the second preset bias power.
The pressure is reduced during the second etching, the radio frequency power and the bias power are increased, and the plasma can be deeper and even deeper to the bottom of the groove so as to meet the etching requirement of the groove with larger depth. In addition, in the first etching, the etching depth is about 1.5 μm in about 120s, if the etching time is less than 110s, the mask is insufficient to cause the etching of the top of the trench under high radio frequency power and bias power in the second etching, and if the etching time is more than 130s, the plasma cannot penetrate further into the bottom of the trench, so that the etching is stopped, the etching morphology becomes unnecessary, and unnecessary waste is caused.
It should be appreciated that in other embodiments, the second etching may be further followed by a third etching, a fourth etching, etc., which are not specifically limited herein; and the pressure of each subsequent etching is gradually reduced, the radio frequency power and the bias power are gradually increased, and the flow of the process gas is finely adjusted so that the depth of each subsequent etching can be further deepened.
Optionally, the second preset pressure is 5-60mtorr (e.g., 5mtorr, 10mtorr, 15mtorr, 20mtorr, 25mtorr, 30mtorr, 35mtorr, 40mtorr, 45mtorr, 50mtorr, 55mtorr, 60mtorr, etc.), the second preset radio frequency power is less than or equal to 2000w (e.g., 2000w, 1800w, 1600w, 1400w, 1300w, 1000w, 800w, 600w, 500w, 300w, 100w, 50w, 10w, etc.), and the second preset bias power is less than or equal to 1000w (e.g., 1000w, 800w, 600w, 500w, 400w, 350w, 300w, 250w, 200w, 180w, 100w, 50w, 10w, etc.); the second etch is performed for a period of 170-190s (e.g., 170s, 175s, 180s, 185s, 190s, etc.).
In a preferred embodiment, the main etching gas SF for controlling the first etching 6 The flow rate of the first etching is 20-150sccm, and the CBr of the first etching is controlled 4 The flow rate of the first etching is 20-180sccm, and the O of the first etching is controlled 2 The flow rate of Ar in the first etching is controlled to be 10-180 sccm; controlling the temperature of the first etching to be 60-80 ℃; main etching gas SF for controlling second etching 6 The flow rate of the second etching is 20-150sccm, and the CBr of the second etching is controlled 4 Flow rate of 20-180sccm, controlling O of the second etching 2 The flow rate of Ar in the second etching is controlled to be 10-180 sccm; the temperature of the second etching is controlled to be 60-80 ℃.
Further, the first preset pressure is 40mtorr, the first preset radio frequency power is 1200w, and the main etching gas SF of the first etching is controlled 6 30sccm, controlling the CBr of the first etch 4 Is 100sccm, controls the O of the first etching 2 The flow rate of Ar in the first etching is controlled to be 50sccm; controlling the temperature of the first etching to be 60 ℃ and the time of the first etching to be 120s; the first preset bias power is 100w; the second preset pressure is 15mtorr, the second preset radio frequency power is 1600w, the second preset bias power is 180w, and the main etching gas SF of the second etching is controlled 6 Is 50sccm, and controls CBr of the second etching 4 Flow 120sccm, controlling the second etch O 2 The flow rate of Ar in the second etching is controlled to be 30sccm, and the flow rate of Ar in the second etching is controlled to be 50 sccn; controlling the temperature of the second etchingThe second etching time was controlled to 180s at 60 ℃.
Referring to fig. 1, the present embodiment further provides a SiC etching apparatus 010 for the above etching method, which may refer to an ICP inductively coupled plasma etching apparatus, and may be used to implement the above etching method; the SiC etching equipment 010 comprises an etching device body 100 and a gas heating device 200, wherein the etching device body 100 is provided with an etching cavity 110, and the etching cavity 110 is used for placing a silicon carbide wafer; the gas heating device 200 is connected with the etching device body 100 and is communicated with the etching chamber 110 through a gas pipe 210, and the gas heating device 200 is used for fixing CBr in a solid state 4 Sublimating into a gaseous state to cause CBr in the gaseous state 4 Is delivered into the etching chamber 110 through the air pipe 210; the outside of the air pipe 210 is wrapped with a heat-insulating layer.
Solid CBr by providing a gas heating device 200 4 Sublimating into gas state, and delivering into the etching chamber 110 to ensure CBr 4 Stable transport of gas; while for conveying CBr 4 The gas is thermally insulated from the gas tube 210 of the etching chamber 110 to prevent clogging caused by sublimation crystals generated in the gas tube 210, thereby ensuring reliable etching.
Optionally, the gas heating device 200 includes a heating assembly and a heating chamber, the heating assembly is disposed at the periphery of the heating chamber, and the heating chamber is used for placing solid CBr 4 And the heating chamber communicates with the etching chamber 110 through the gas pipe 210. Heating elements include, but are not limited to, resistive heating elements, ceramic heating elements.
It should be noted that other structures and operation principles of the SiC etching apparatus 010 are similar to those of the ICP inductive coupling plasma etching apparatus provided in the related art, and will not be described herein.
Example 1
The depth of the etched groove is 1 μm, and the diagrams before and after etching are shown in fig. 2-5.
Removing the surface hard shell layer: the control pressure is 40mtorr, the radio frequency power is 600W, and the gas is CF 4 The flow rate was 100sccm, the temperature was 60℃and the time was 15s.
Stabilizing pressure: the control pressure is 20mtorr, and the main etching gas is SF 6 Stream, streamThe amount was 30sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 100sccm, O 2 The flow rate is 50sccm; ar flow is 100sccm; the temperature was set at 60℃for 5s.
Etching: the control pressure is 40mtorr, the radio frequency power is 1600w, the bias power is 250w, and the main etching gas is SF 6 The flow is 30sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 100sccm, O 2 The flow rate was set to 50sccm and the Ar flow rate was set to 100sccm; the temperature was 60℃for 360s.
Example 2
The depth of the etched trench was 0.9 μm.
Removing the surface hard shell layer: the control pressure is 60mtorr, the radio frequency power is 800W, and the gas is CF 4 The flow rate was 120sccm, the temperature was 70℃and the time was 10s.
Stabilizing pressure: the control pressure is 50mtorr, and the main etching gas is SF 6 The flow rate is 50sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 120sccm, O 2 The flow rate is 80sccm; ar flow is 150sccm; the temperature was set at 80℃for 3s.
Etching: the control pressure is 50mtorr, the radio frequency power is 1500w, the bias power is 200w, and the main etching gas is SF 6 The flow rate is 50sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 120sccm, O 2 The flow rate was set at 80sccm and the Ar flow rate was set at 150sccm; the temperature was 80℃for 370s.
Example 3
The depth of the etched trench was 1.2 μm, and the diagrams before and after etching are shown in fig. 6 and 7.
Removing the surface hard shell layer: the control pressure is 40mtorr, the radio frequency power is 600w, and the gas is CF 4 The flow rate was 100sccm, the temperature was set at 60℃and the time was 10s.
First etching: the control pressure is 40mtorr, the radio frequency power is 1200w, the bias power is 100w, and the main etching gas is SF 6 The flow rate is 30sccm, and the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 100sccm, O 2 The flow rate was 50sccm, the Ar flow rate was 50sccm, the temperature was 60℃and the time was 120s.
And (3) second etching: the control pressure is 15mtorr, the radio frequency power is 1600w, the bias power is 180w, and the main etching gas is SF 6 The flow rate is 50sccm, and the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 120sccm, O 2 The flow rate was 30sccm, ar flow rate was 30sccm, the temperature was 60℃and the time was 180s.
Example 4
The depth of the etched trench was 1.3 μm.
Removing the surface hard shell layer: the control pressure is 60mtorr, the radio frequency power is 1000w, and the gas is CF 4 The flow rate was 180sccm, the temperature was set at 80℃and the time was 15s.
First etching: the control pressure is 60mtorr, the radio frequency power is 1500w, the bias power is 160w, and the main etching gas is SF 6 The flow rate is 100sccm, and the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 120sccm, O 2 The flow rate was 80sccm, ar flow rate was 80sccm, the temperature was 80℃and the time was 125s.
And (3) second etching: the control pressure is 35mtorr, the radio frequency power is 1800w, the bias power is 250w, and the main etching gas is SF 6 The flow rate is 120sccm, and the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 The flow rate was 150sccm, O 2 The flow rate was 50sccm, ar flow rate was 50sccm, the temperature was 80℃and the time was 185s.
Comparative example 1
Comparative example 1 is similar to example 1, except that:
stabilizing pressure: the control pressure is 40mtorr, and the main etching gas is SF 6 The flow rate is 25sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 80sccm, O 2 The flow rate is 15sccm; ar flow is 40sccm; the temperature was set at 60℃for 5s.
Etching: the control pressure is 40mtorr, the radio frequency power is 1500w, the bias power is 80w, and the main etching gas is SF 6 The flow rate is25sccm; the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 80sccm, O 2 The flow rate was set to 15sccm and the Ar flow rate was set to 40sccm; the temperature was 60℃for 350s. The depth after etching was 1.0. Mu.m.
Other process parameters are described in example 1.
As can be seen from a comparison of fig. 8 and 3, the roughness of the trenches obtained after etching in comparative example 1 is large.
Comparative example 2
Comparative example 2 is similar to example 3, except that:
first etching: the control pressure is 40mtorr, the radio frequency power is 1200w, the bias power is 160w, the HBr flow is 150sccm, O 2 The flow rate was 15sccm and the Ar flow rate was 60sccm.
And (3) second etching: the control pressure is 15mtorr, the radio frequency power is 1600w, the bias power is 185w, the HBr flow is 160sccm, O 2 The flow rate was 20sccm and the Ar flow rate was 50sccm.
Other process parameters are described in example 3. As is clear from fig. 9, the depth after etching was 2.7 μm, but the sidewall had streak-like groove marks due to insufficient protection of the sidewall by HBr, and the roughness was large.
Comparative example 3
Comparative example 3 is similar to example 3 except that only the first etch is used:
first etching: the control pressure is 40mtorr, the radio frequency power is 1200w, the bias power is 100w, and the main etching gas is SF 6 The flow rate is 30sccm, and the auxiliary gas is CBr 4 、O 2 And Ar, CBr 4 Flow rate is 100sccm, O 2 The flow rate was 50sccm, ar flow rate was 50sccm, the temperature was 60℃and the time was 300s.
Other process parameters are described in example 3. As shown in FIG. 10, the single step etching process resulted in bottom etch stagnation due to the lower bias power, the post-etch topography was not desired, and the etch depth was approximately 2 μm.
In summary, the SiC etching method of the present invention can reduce the roughness of the sidewall of the trench etched on the SiC substrate, reduce the possibility of breakdown of trench gate oxide, and further improve the reliability of the semiconductor device.
The present invention is not limited to the above embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (8)

1. The SiC etching method is characterized by being used for etching a SiC substrate with a mask, wherein the mask is provided with a preset groove; the SiC etching method comprises the following steps: removing a crust layer at the bottom of the preset groove, and performing single-step etching or multi-step etching;
the step of removing the crust layer at the bottom of the preset groove comprises the following steps: by CF 4 Removing a hard shell layer at the bottom of the preset groove by gas;
the step of single-step etching or multi-step etching comprises the following steps: using main etching gas SF 6 And an auxiliary etching gas for etching the SiC substrate, wherein the auxiliary etching gas comprises CBr 4 Gas to generate SiBr 4 Attaching the side wall of the groove etched on the SiC substrate;
the single-step etching step specifically comprises the following steps: controlling the pressure of the chamber to be 5-60mtorr during etching, controlling the radio frequency power to be less than or equal to 2000w, and controlling the bias power to be less than or equal to 1000w;
controlling the main etching gas SF 6 The flow rate of (2) is less than or equal to 200sccm, the CBr 4 The flow rate of the gas is less than or equal to 200sccm, and the auxiliary etching gas also comprises O 2 And Ar, said O 2 The flow rate of Ar is less than or equal to 200sccm, and the flow rate of Ar is less than or equal to 500sccm; controlling the etching temperature to be less than or equal to 100 ℃;
the step of multi-step etching includes at least a first etch and a second etch, wherein,
the first etching step specifically includes: controlling the etching pressure to be a first preset pressure and controlling the radio frequency power to be a first preset pressureThe bias power is controlled to be a first preset bias power; the main etching gas SF for controlling the first etching 6 The flow rate of the auxiliary etching gas in the first etching is less than or equal to 200sccm, and the auxiliary etching gas in the first etching also comprises O 2 And Ar, controlling the CBr of the first etching 4 And controlling the O of the first etching to a flow rate of 200sccm or less 2 The flow rate of Ar in the first etching is controlled to be less than or equal to 200sccm; controlling the temperature of the first etching to be-20-100 ℃ and controlling the time of the first etching to be 110-130s;
the second etching step specifically comprises the following steps: controlling etching pressure to be a second preset pressure, controlling radio frequency power to be a second preset radio frequency power, and controlling bias power to be a second preset bias power; the main etching gas SF for controlling the second etching 6 The flow rate of the auxiliary etching gas is less than or equal to 200sccm, and the auxiliary etching gas during the second etching also comprises O 2 And Ar, said CBr controlling said second etch 4 And controlling the O of the second etch to a flow of less than or equal to 200sccm 2 The flow rate of Ar of the second etching is controlled to be less than or equal to 200sccm; controlling the temperature of the second etching to be-20-100 ℃;
the first preset pressure is greater than the second preset pressure, the first preset radio frequency power is smaller than the second preset radio frequency power, and the first preset bias power is smaller than the second preset bias power.
2. The SiC etching method according to claim 1, wherein the etching time of the single-step etching step is 350 to 370s.
3. The SiC etching method according to any one of claims 1 to 2, further comprising a voltage stabilizing step performed between the step of removing the crust layer at the bottom of the preset trench and the step of single-step etching, the voltage stabilizing step comprising:
at the settingIntroducing the main etching gas SF into the etching process cavity under the conditions of the cavity pressure and the set temperature 6 And the auxiliary etching gas.
4. A SiC etching method according to claim 3, characterized in that the voltage stabilizing step specifically includes: setting the pressure of the chamber to be 5-60mtorr, and setting the temperature of the ESC electrostatic chuck to be-20-100 ℃; introducing the main etching gas SF into the etching process chamber 6 And the duration of the auxiliary etching gas is 3-5s, wherein the auxiliary etching gas comprises CBr 4 、O 2 And Ar;
introducing the main etching gas SF into the etching process chamber 6 When the flow is less than or equal to 200sccm, introducing the CBr into the etching process cavity 4 When the flow is less than or equal to 200sccm, introducing the O into the etching process cavity 2 The flow rate is less than or equal to 200sccm, and the flow rate is less than or equal to 500sccm when Ar is introduced into the etching process chamber.
5. The SiC etching method according to claim 1, wherein the second preset pressure is 5-60mtorr, the second preset radio frequency power is less than or equal to 2000w, and the second preset bias power is less than or equal to 1000w; the second etching time is 170-190s.
6. The SiC etching method according to claim 1, wherein the CF is used 4 The step of removing the crust layer at the bottom of the preset groove by gas specifically comprises the following steps: controlling the pressure to be 5-60mtorr, controlling the radio frequency power to be less than or equal to 2000w, and controlling the CF 4 The gas flow rate of the gas is less than or equal to 200sccm, and the temperature is controlled to be-20-100 ℃.
7. The SiC etching method according to claim 6, wherein the CF is used 4 The time for removing the crust layer at the bottom of the preset groove by gas is 10-15s.
8. SiC etching apparatus, characterized by being used in the SiC etching method according to any one of claims 1 to 7; the SiC etching apparatus includes: the etching device comprises an etching device body and a gas heating device, wherein the etching device body is provided with an etching cavity, and the etching cavity is used for placing a silicon carbide wafer; the gas heating device is connected with the etching device body and communicated with the etching cavity through a gas pipe, and is used for fixing solid CBr 4 Sublimating into a gaseous state, so that the CBr in the gaseous state 4 The etching reaction is carried into the etching cavity through an air pipe; the outside of the air pipe is wrapped with an insulating layer.
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CN110277315A (en) * 2019-05-13 2019-09-24 全球能源互联网研究院有限公司 A kind of silicon carbide shallow trench lithographic method

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