CN104810264B - A kind of SiC terminal structure preparation methods based on ONO structure - Google Patents
A kind of SiC terminal structure preparation methods based on ONO structure Download PDFInfo
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- CN104810264B CN104810264B CN201410036304.3A CN201410036304A CN104810264B CN 104810264 B CN104810264 B CN 104810264B CN 201410036304 A CN201410036304 A CN 201410036304A CN 104810264 B CN104810264 B CN 104810264B
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- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 92
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 47
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 35
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052751 metal Inorganic materials 0.000 claims abstract description 31
- 239000002184 metal Substances 0.000 claims abstract description 31
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000005530 etching Methods 0.000 claims abstract description 18
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 12
- 229920002120 photoresistant polymer Polymers 0.000 claims abstract description 6
- 238000001259 photo etching Methods 0.000 claims abstract description 4
- 238000012546 transfer Methods 0.000 claims abstract description 4
- 238000009616 inductively coupled plasma Methods 0.000 claims description 34
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 claims description 29
- 238000001020 plasma etching Methods 0.000 claims description 27
- 238000001312 dry etching Methods 0.000 claims description 25
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 24
- 229910018503 SF6 Inorganic materials 0.000 claims description 20
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 239000007789 gas Substances 0.000 claims description 12
- 235000012239 silicon dioxide Nutrition 0.000 claims description 12
- 238000001039 wet etching Methods 0.000 claims description 12
- 229960000909 sulfur hexafluoride Drugs 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 8
- 238000000137 annealing Methods 0.000 claims description 7
- 238000005229 chemical vapour deposition Methods 0.000 claims description 7
- 238000004518 low pressure chemical vapour deposition Methods 0.000 claims description 6
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000012298 atmosphere Substances 0.000 claims description 4
- 238000005566 electron beam evaporation Methods 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 238000001505 atmospheric-pressure chemical vapour deposition Methods 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 230000003628 erosive effect Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 5
- 239000004065 semiconductor Substances 0.000 abstract description 4
- 239000002689 soil Substances 0.000 abstract description 4
- 238000000151 deposition Methods 0.000 description 7
- 230000008021 deposition Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910001413 alkali metal ion Inorganic materials 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- BYACHAOCSIPLCM-UHFFFAOYSA-N 2-[2-[bis(2-hydroxyethyl)amino]ethyl-(2-hydroxyethyl)amino]ethanol Chemical group OCCN(CCO)CCN(CCO)CCO BYACHAOCSIPLCM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- -1 fluoroform Alkane Chemical class 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/0445—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising crystalline silicon carbide
- H01L21/048—Making electrodes
- H01L21/0485—Ohmic electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
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- H01L29/1608—
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- Manufacturing & Machinery (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Drying Of Semiconductors (AREA)
- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
- Element Separation (AREA)
Abstract
The present invention relates to technical field of semiconductors, and in particular to a kind of SiC terminal structure preparation methods based on ONO structure.This method comprises the steps：Step 1, ONO structure is deposited in silicon carbide substrate surface；Step 2, photoresist is coated on ONO structure, the pattern transfer of table top is formed using photoetching process；Step 3, the silica of the superiors in ONO structure is performed etching, expose the silicon nitride in intermediate layer；Step 4, to the silicon nitride etch in the intermediate layer in ONO structure, and it is etched to the silica of the bottom；Step 5, third layer residue silica in ONO structure is performed etching, exposes silicon carbide substrates active area；Step 6, silicon carbide substrates are annealed；Step 7, deposited metal, form Metal field plate.Method provided by the invention avoids the damage of silicon carbide substrates active area, avoids Metal field plate corner from being broken, the effect for having extremely steady chemical property, insulating property (properties) and isolating metal ionic soil.
Description
Technical field
The present invention relates to technical field of semiconductors, and in particular to a kind of SiC terminal structures preparation side based on ONO structure
Method.
Background technology
Usual offset field plate is to connect the metal being covered on substrate surface SiO2 layers of main knot, passes through the biasing on field plate
Pressure can make depletion layer along surface to main knot outer expandable, and breakdown voltage is improved with this.Metal field plate manufacture is very simple,
It can be formed together with device electrode, without increasing single processing step.Offset field plate to the sucking action of electric charge in medium,
So that using the device of this terminal technology to interface charge（Especially movable charge）It is not very sensitive.
With the development of semiconductor power device, third generation wide bandgap semiconductor silicon carbide power electronic device progressively turns into
Development trend.At present, in silicon carbide device terminal structure, the part of the terminal structure one using thick SiO2 as Metal field plate.
Although it machinery, chemistry and electrically etc. be all highly stable, there is good passivation.But in field plate edge
It is very big to locate potential difference between field plate and substrate, so electric-field intensity is larger herein, breakdown easily occurs in advance in low voltage,
And be likely to occur at surface, there is higher requirement to dielectric layer.Therefore this technology is used alone to be not suitable for compared with high strike
Wear the discrete device of voltage.Additionally due to the Some features that itself is intrinsic, cause to shelter energy to alkali metal ions such as Na+, K+
Power is poor, influences device performance.
In the terminal manufacturing process of silicon carbide power device, the not specially treated ONO structure of generally use, laying gold
Belong to field plate as terminal structure, reached with this and reduce internal field, improve surface breakdown voltage and reliability, make device is actual to hit
Wear the special construction that voltage specially designs closer to parallel plane knot ideal value.On the other hand effect is also functioned to passivation, can
To prevent steam and Na+Into substrate.
Using not specially treated ONO structure, etch and expose active area and fill Metal field plate, at present, the knot
The defects of structure, is, while etching ONO structure, the possibility of easily damage silicon carbide substrates be present；The Metal field plate of deposition exists
The possibility of fracture at the silica trench corner of the top be present, have grave danger to the normal use of electrode.
The content of the invention
In view of the shortcomings of the prior art, it is an object of the invention to provide a kind of SiC terminal structures preparation based on ONO structure
Method, ONO structure in current carborundum terminal structure is optimized.
The purpose of the present invention is realized using following technical proposals：
The present invention provides a kind of SiC terminal structure preparation methods based on ONO structure, and it is theed improvement is that, the side
Method comprises the steps：
Step 1, ONO structure is deposited in silicon carbide substrate surface；
Step 2, photoresist is coated on ONO structure, the pattern transfer of table top is formed using photoetching process；
Step 3, the silica of the superiors in ONO structure is performed etching, expose the silicon nitride in intermediate layer；
Step 4, to the silicon nitride etch in the intermediate layer in ONO structure, and it is etched to the silica of the bottom；
Step 5, third layer residue silica in ONO structure is performed etching, exposes silicon carbide substrates active area；
Step 6, silicon carbide substrates are annealed；
Step 7, deposited metal, form Metal field plate.
Further, in the step 1, one layer is deposited in silicon carbide substrate surfaceSilica,
One layer is deposited in silicon dioxide layerSilicon nitride, finally on silicon nitride layer deposit one layer's
Silica.
Further, in the step 1, using enhanced plasma activated chemical vapour deposition PECVD, low pressure chemical gas
Mutually deposition LPCVD, aumospheric pressure cvd APCVD, or inductively coupled plasma chemical vapor deposition ICP-CVD depositions two
Silicon oxide layer and silicon nitride layer.
Further, in the step 3, using the silica of the superiors in wet etching ONO structure, ladder is formed
The gentle groove through hole of shape, adjusted by the proportioning of hydrofluoric acid cushioning liquid, the gentle groove is adjusted between 5 ° to 85 °
It is whole；Or
Using the silica of the superiors in dry etching ONO structure, the gentle groove through hole of inverted trapezoidal is formed, passes through work
The adjustment of skill gas, pressure and power, the gentle groove are adjusted between 5 ° to 85 °.
Further, in the step 4, vertical trench through hole is formed using dry etching intermediate layer silicon nitride, and etch
To the silica of the bottom.
Further, in the step 5, the two of the bottom is etched by the way of dry etching and wet etching combine
Silica forms transverse concave groove structure, apart from this layer of bottomThere is transverse concave groove structure in the groove at place, laterally
Groove using upper bit as vertical through hole, and silicon carbide substrates active area is exposed.
Further, the hydrofluoric acid cushioning liquid hydrofluoric acid in the wet etching：The ratio of ammonium fluoride is 1：1 to 1：
50。
Further, the dry etching includes reactive ion etching RIE and inductively coupled plasma etching ICP
Further, made using the reactive ion etching RIE in dry etching, the process gas fluoroform CHF3 used
Dosage is 10~50sccm, sulfur hexafluoride SF6 usage amounts are 1~20sccm, oxygen O2 usage amounts are 1~25sccm, react from
Son etching RIE radio-frequency power is 100~500W, and air pressure is 500~2500mTorr in reactive ion etching RIE equipment cavities.
Further, ICP, the process gas fluoroform used are etched using inductively coupled plasma in dry etching
CHF3 usage amounts are 5~40sccm, sulfur hexafluoride SF6 usage amounts are 1~45sccm, oxygen O2 usage amounts are 1~20sccm, electricity
Sense coupled plasma etch ICP radio-frequency power is 100~500W, ICP power is 100~3000W, and inductively coupled plasma is carved
It is 5~60mTorr to lose air pressure in ICP equipment cavities.
Further, in the step 6, the annealing way used is short annealing, in nitrogen atmosphere or oxygen atmosphere
In, for temperature in 400~1500 degree Celsius ranges, the retention time is 1~20 minute.
Further, in the step 7, deposited metal uses electron-beam evaporation mode or magnetron sputtering mode；It is heavy first
Thickness is accumulated as the Ti in the range of 1~15nm, the Ni in the range of 200~700nm of redeposition, last deposit thickness is 100~500nm
In the range of Ag or Al or Cu.
Compared with the prior art, the beneficial effect that reaches of the present invention is：
1. forming the gentle groove through hole of inverted trapezoidal using the silica of the superiors in wet etching ONO structure, pass through
The proportioning adjustment of hydrofluoric acid cushioning liquid, the groove can be adjusted between 5 ° to 85 ° as needed.Avoid Metal field plate
The possibility of fracture be present in corner.
2. forming the gentle groove through hole of inverted trapezoidal using the silica of the superiors in dry etching ONO structure, pass through
The adjustment of process gas, pressure, power, the groove can be adjusted between 5 ° to 85 ° as needed.Avoid Metal field plate
The possibility of fracture be present in corner.
3. etching angle can effectively be controlled using dry etching.Dry etching intermediate layer silicon nitride forms vertical trench and led to
Hole.
4. the through hole that third layer silica forms special appearance is etched by the way of dry and wet combination, pattern point
For two parts, the first half is vertical trench, and lower half groove has transverse concave groove structure, and the purpose for preparing the structure is to avoid
The damages of silicon carbide substrates active areas.
5. handling the ONO structure after etching using short annealing mode, make ONO structure finer and close, compare without spy
The ONO structure very handled, there is the effect of extremely steady chemical property, insulating property (properties) and isolating metal ionic soil.
6. avoiding the damage of silicon carbide substrates active area, avoid Metal field plate corner from being broken, have extremely steady
The effect of chemical property, insulating property (properties) and isolating metal ionic soil.
Brief description of the drawings
Fig. 1 is the schematic diagram after the ONO structure processing of prior art；
Fig. 2 is the schematic diagram before ONO structure processing；
Fig. 3 is the schematic diagram after the ONO structure processing of the embodiment of the present invention；
Fig. 4 is after the ONO structure of the embodiment of the present invention is processed and the schematic diagram of deposited metal field plate；
Wherein：The silicon dioxide layer of the 1- the superiors；2- middle nitride silicon；3- bottom silica；4- metal fields are hardened
Structure.
Embodiment
The embodiment of the present invention is described in further detail below in conjunction with the accompanying drawings.
The present invention provides a kind of preparation method using specially treated ONO structure SiC terminal structures；It is specially treated
Afterwards, this configuration avoids the possibility that active area is damaged during cutting, and the possibility being broken during laying Metal field plate.Advantage：Avoid
The damage of silicon carbide substrates active areas, avoids Metal field plate corner from being broken, there is extremely steady chemical property, insulating properties
The effect of matter and isolating metal ionic soil.
The method of the present invention comprises the steps：
Step 1, ONO structure is deposited in silicon carbide substrate surface：One layer is deposited in silicon carbide substrate surface
Silica, in silicon dioxide layer deposit one layerSilicon nitride, finally on silicon nitride layer deposit one layerSilica.
Using enhanced plasma activated chemical vapour deposition PECVD, low-pressure chemical vapor deposition LPCVD, normal pressure chemical gas
Mutually deposition APCVD, or inductively coupled plasma chemical vapor deposition ICP-CVD deposited silicon dioxide layers and silicon nitride layer.
Step 2, photoresist is coated on ONO structure, the pattern transfer of table top is formed using photoetching process：In ONO structure
It is upper that patterned mask layer is formed using photoresist, define the region for needing to open a window in ONO structure.
Step 3, the silica of the superiors in ONO structure is performed etching, expose the silicon nitride in intermediate layer：Using
The silica of the superiors in wet etching ONO structure, the gentle groove through hole of inverted trapezoidal is formed, passes through hydrofluoric acid cushioning liquid
Proportioning adjustment, the gentle groove is adjusted between 5 ° to 85 °；Or
Using the silica of the superiors in dry etching ONO structure, the gentle groove through hole of inverted trapezoidal is formed, passes through work
The adjustment of skill gas, pressure and power, the gentle groove are adjusted between 5 ° to 85 °.
Step 4, vertical trench through hole is formed using the intermediate layer silicon nitride in dry etching ONO structure, and be etched to most
The silica of bottom.
Step 5, third layer residue silica in ONO structure is performed etching, exposes silicon carbide substrates active area；
Specially：The silica that the bottom is etched by the way of dry etching and wet etching combine forms transverse concave groove structure,
Apart from this layer of bottomThere is transverse concave groove structure in the groove at place, transverse concave groove leads to using upper bit to be vertical
Hole, and silicon carbide substrates active area is exposed.
Hydrofluoric acid cushioning liquid hydrofluoric acid in wet etching：The ratio of ammonium fluoride is 1：1 to 1：50.
Dry etching includes reactive ion etching RIE and inductively coupled plasma etching ICP；
Using the reactive ion etching RIE in dry etching, the process gas fluoroform CHF3 usage amounts used are 10
~50sccm, sulfur hexafluoride SF6 usage amounts are 1~20sccm, oxygen O2 usage amounts are 1~25sccm, reactive ion etching RIE
Radio-frequency power be 100~500W, air pressure is 500~2500mTorr in reactive ion etching RIE equipment cavities.
ICP, the process gas fluoroform CHF3 usage amounts used are etched using inductively coupled plasma in dry etching
For 5~40sccm, sulfur hexafluoride SF6 usage amounts be 1~45sccm, oxygen O2 usage amounts be 1~20sccm, inductive etc. from
Son etching ICP radio-frequency power is 100~500W, ICP power is 100~3000W, and inductively coupled plasma etches ICP equipment
Air pressure is 5~60mTorr in cavity.
Step 6, silicon carbide substrates are annealed：The annealing way used is short annealing, in nitrogen atmosphere or oxygen
In atmosphere, for temperature in 400~1500 degree Celsius ranges, the retention time is 1~20 minute.
Step 7, deposited metal, form Metal field plate：Deposited metal uses electron-beam evaporation mode or magnetron sputtering side
Formula；Deposit thickness first is the Ti in the range of 1~15nm, the Ni in the range of 200~700nm of redeposition, and last deposit thickness is
Ag or Al or Cu in the range of 100~500nm.
Embodiment
Step 1, as shown in Fig. 2 use LPCVD in sequence silicon carbide substrate surface deposit first a layer thickness forSilica 3, preferred thickness isIt is in deposition a layer thickness againSilicon nitride 2,
Preferred thickness isIt is in deposition a layer thickness again finallySilica 1, preferred thickness isNow, ONO structure has been formd.
Step 2, patterned mask layer is formed using photoresist on ONO structure, define needs out in ONO structure
The region of window.
Step 3, using wet etching hydrofluoric acid cushioning liquid（Hydrofluoric acid：Ammonium fluoride=1:30）, corrode the two of the superiors
Silicon oxide layer 1, etching time are 2 minutes.Reactive ion etching can also be used（RIE）, fluoroform（CHF3）Usage amount is
10~50sccm, preferred parameter 30sccm, sulfur hexafluoride（SF6）Usage amount is 1~20sccm, preferred parameter 10sccm,
Oxygen（O2）Usage amount is 1^25sccm, preferred parameter 8sccm, and radio-frequency power is 100~500W, preferred parameter 350W,
Air pressure is 500~2500mTorr, preferred parameter 750mTorr.
Inductively coupled plasma can also be used to etch（ICP）, fluoroform（CHF3）Usage amount is 5~40sccm, excellent
It is 25sccm to select parameter, sulfur hexafluoride（SF6）Usage amount is 1~45sccm, preferred parameter 15sccm, oxygen（O2）Usage amount
For 1~20sccm, preferred parameter 4sccm, radio-frequency power is 100~500W, preferred parameter 400W, ICP power is 100~
3000W, preferred parameter 1200W, air pressure are 5~60mTorr, preferred parameter 30mTorr.Now silicon dioxide layer 1 occurs
The gentle groove of inverted trapezoidal, trench angles are 40 °, and expose intermediate layer silicon nitride layer 2.The formation of gentle groove,
Eliminate the possibility that subsequent deposition Metal field plate has fracture.
Step 4, using dry etching silicon nitride layer 2, dry etching can use reactive ion etching（RIE）, fluoroform
Alkane（CHF3）Usage amount is 10~50sccm, preferred parameter 40sccm, sulfur hexafluoride（SF6）Usage amount is 1~20sccm, excellent
It is 12sccm to select parameter, oxygen（O2）Usage amount is 1^25sccm, and preferred parameter 8sccm, radio-frequency power is 100~500W,
Preferred parameter is 100W, and air pressure is 500~2500mTorr, preferred parameter 1850mTorr.
Dry etching can also use inductively coupled plasma to etch（ICP）, fluoroform（CHF3）Usage amount be 5~
40sccm, preferred parameter 35sccm, sulfur hexafluoride（SF6）Usage amount is 1~45sccm, preferred parameter 10sccm, oxygen
（O2）Usage amount is 1~20sccm, and preferred parameter 8sccm, radio-frequency power is 100~500W, preferred parameter 300W, ICP
Power is 100~3000W, and preferred parameter 200W, air pressure is 5~60mTorr, preferred parameter 20mTorr.Now, nitrogenize
Silicon layer 2 forms vertical through hole, and crosses and be carved into the silicon dioxide layer 3 of third layer, makes the residual thickness of silica 3 be
Step 5, the remaining silicon dioxide layer 3 of wet etching third layer, exposes active area.Avoid due to dry etching
Grasp and bad cause substrate active area.Now, the silicon dioxide layer 3 of third layer forms irregular after over etching
Through hole.Through hole is divided into two parts, this layer of bottom of distance in grooveIn the range of depths, transverse concave groove structure be present,
Transverse concave groove using upper bit as vertical through hole.
Step 6, as shown in figure 3, to the above-mentioned ONO structure after lithography, quickly moved back in oxygen atmosphere
400~1500 degrees Celsius of fire, 900 degrees Celsius of preferred parameter, kept for 1~20 minute, preferred parameter 14 minutes.Moving back the structure
Become finer and close during fire, to stop that the pollution of the alkali metal ions such as Na+, K+ provides effective guarantee.
Step 7, as shown in figure 4, using electron-beam evaporation metal in the overlying regions of having chance with exposed.First deposit
Thickness is the Ti in the range of 1~15nm, the Ni in the range of preferred thickness 8nm, 200~700nm of redeposition, and preferred thickness is
630nm, last deposit thickness are the Cu, preferred thickness 450nm in the range of 100~500nm.Now, Metal field plate is formd
Structure 4.
Finally it should be noted that：The above embodiments are merely illustrative of the technical scheme of the present invention and are not intended to be limiting thereof, to the greatest extent
The present invention is described in detail with reference to above-described embodiment for pipe, those of ordinary skills in the art should understand that：Still
The embodiment of the present invention can be modified or equivalent substitution, and without departing from any of spirit and scope of the invention
Modification or equivalent substitution, it all should cover among scope of the presently claimed invention.
Claims (1)
1. a kind of SiC terminal structure preparation methods based on ONO structure, it is characterised in that methods described comprises the steps：
Step 1, ONO structure is deposited in silicon carbide substrate surface；
Step 2, photoresist is coated on ONO structure, the pattern transfer of table top is formed using photoetching process；
Step 3, the silica of the superiors in ONO structure is performed etching, expose the silicon nitride in intermediate layer；
Step 4, to the silicon nitride etch in the intermediate layer in ONO structure, and it is etched to the silica of the bottom；
Step 5, third layer residue silica in ONO structure is performed etching, exposes silicon carbide substrates active area；
Step 6, silicon carbide substrates are annealed；
Step 7, deposited metal, form Metal field plate；
In the step 1, one layer is deposited in silicon carbide substrate surfaceSilica, in silicon dioxide layer sink
One layer of productSilicon nitride, finally on silicon nitride layer deposit one layerSilica；
In the step 1, using enhanced plasma activated chemical vapour deposition PECVD, low-pressure chemical vapor deposition LPCVD, often
Pressure chemical vapor deposition APCVD, or inductively coupled plasma chemical vapor deposition ICP-CVD deposited silicon dioxide layers and nitridation
Silicon layer；
In the step 3, using the silica of the superiors in wet etching ONO structure, the gentle groove for forming inverted trapezoidal leads to
Hole, adjusted by the proportioning of hydrofluoric acid cushioning liquid, the gentle groove is adjusted between 5 ° to 85 °；Or
Using the silica of the superiors in dry etching ONO structure, the gentle groove through hole of inverted trapezoidal is formed, passes through process gas
The adjustment of body, pressure and power, the gentle groove are adjusted between 5 ° to 85 °；
In the step 4, vertical trench through hole is formed using dry etching intermediate layer silicon nitride, and be etched to the two of the bottom
Silica；
In the step 5, the silica that the bottom is etched by the way of dry etching and wet etching combine forms transverse direction
Groove structure, apart from this layer of bottomTransverse concave groove structure be present in the groove at place, transverse concave groove using upper bit as
Vertical through hole, and silicon carbide substrates active area is exposed；
Hydrofluoric acid cushioning liquid hydrofluoric acid in the wet etching：The ratio of ammonium fluoride is 1：1 to 1：50；
The dry etching includes reactive ion etching RIE and inductively coupled plasma etching ICP；
Using the reactive ion etching RIE in dry etching, the process gas fluoroform CHF3 usage amounts used be 10~
50sccm, sulfur hexafluoride SF6 usage amounts are 1~20sccm, oxygen O2 usage amounts are 1~25sccm, reactive ion etching RIE's
Radio-frequency power is 100~500W, and air pressure is 500~2500mTorr in reactive ion etching RIE equipment cavities；
Using in dry etching inductively coupled plasma etch ICP, the process gas fluoroform CHF3 usage amounts used be 5~
40sccm, sulfur hexafluoride SF6 usage amounts are 1~45sccm, oxygen O2 usage amounts are 1~20sccm, and inductively coupled plasma is carved
Erosion ICP radio-frequency power is 100~500W, ICP power is 100~3000W, and inductively coupled plasma etches ICP equipment cavities
Interior air pressure is 5~60mTorr；
In the step 6, the annealing way used is short annealing, in nitrogen atmosphere or oxygen atmosphere, temperature 400~
In 1500 degree Celsius ranges, the retention time is 1~20 minute；
In the step 7, deposited metal uses electron-beam evaporation mode or magnetron sputtering mode；First deposit thickness be 1~
Ni in the range of Ti in the range of 15nm, 200~700nm of redeposition, last deposit thickness are the Ag in the range of 100~500nm
Or Al or Cu.
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| US20070018199A1 (en) * | 2005-07-20 | 2007-01-25 | Cree, Inc. | Nitride-based transistors and fabrication methods with an etch stop layer |
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| CN102148157A (en) * | 2009-12-23 | 2011-08-10 | 英特赛尔美国股份有限公司 | Producing method of enhanced HEMT with self-aligned filed plate |
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