CN207165577U - A kind of SiC ohmic contact structure - Google Patents
A kind of SiC ohmic contact structure Download PDFInfo
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- CN207165577U CN207165577U CN201720867878.4U CN201720867878U CN207165577U CN 207165577 U CN207165577 U CN 207165577U CN 201720867878 U CN201720867878 U CN 201720867878U CN 207165577 U CN207165577 U CN 207165577U
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Abstract
A kind of SiC ohmic contact structure is the utility model is related to, including：SiC substrate 11；First Ni layers 12, it is arranged in the SiC substrate 11；Ti layers 13, it is arranged on the first Ni layers 12；2nd Ni layers 14, it is arranged on the Ti layers 13；TaSi2Layer 15, is arranged on the 2nd Ni layers 14；Pt layers 16, it is arranged at the TaSi2On layer 15.SiC ohmic contact structure provided by the utility model improves the heat endurance and antioxygenic property of Ohmic contact.
Description
Technical field
The utility model category SiC device manufacturing field, more particularly to a kind of SiC ohmic contact structure.
Background technology
At present, compared to silicon, SiC has excellent physical characteristic, including forbidden band is wide, critical breakdown electric field is high, thermal conductivity
High, electron saturation velocities height, Flouride-resistani acid phesphatase, therefore be adapted to make high temperature, high frequency, high power and Flouride-resistani acid phesphatase electronic device.
Ohmic contact is so that semi-conducting material is applied as a kind of key process technology in semiconductor manufacturing, its purpose
Contact position keeps a situation well under one's control sufficiently small so that not influenceing the performance of device during making alive.If the poor reliability of ohmic contact resistance,
The ON resistance of device can be caused to raise, the performance of device can be influenceed when serious.Prepared by SiC ohmic contact, high due to needing
Annealing temperature, it is necessary to prepare in advance in the preparation process of device, to prevent influence of the high-temperature annealing process to subsequent technique.
But some chemistry, physical actions in subsequent technique, it can also form the destruction to SiC ohmic contact.
Ohmic contact is one of key influence factor that SiC device is applied in the extreme environment such as high temperature, oxidizable, it
Purpose, which is to realize when electrode is in and applies forward voltage, can carry pressure drop as small as possible, with this, to ensure the property of device
Energy.Assuming that ohm contact degradation or failure, certainly will influence the opening resistor of device, device performance can be influenceed when serious, or even
Make component failure.So design good thermal stability, oxidation resistant Ohm contact electrode seem particularly necessary.
At present, SiC ohmic contact metal or alloy layer Problems are weak including oxidation resistance, in atmosphere i.e. by oxygen
Change；Heat endurance is poor, occurs degenerating under high temperature or fails；Hardness is low, easily by mechanical damage the shortcomings of, these shortcomings can make
Ohm contact electrode reliability reduces, seriously limit its application environment and scope, so make the application of SiC device with can
By property by many influences and limitation.
Utility model content
In view of background above, the utility model aims at a kind of high temperature resistant, oxidation resistant ohmic contact structure.
Specifically, the utility model provides a kind of SiC ohmic contact structure, including：
SiC substrate 11；
First Ni layers 12, it is arranged in the SiC substrate 11；
Ti layers 13, it is arranged on the first Ni layers 12；
2nd Ni layers 14, it is arranged on the Ti layers 13；
TaSi2Layer 15, is arranged on the 2nd Ni layers 14；
Pt layers 16, it is arranged at the TaSi2On layer 15.
In one embodiment of the present utility model, the SiC substrate 11 is 4H-SiC substrates or 6H-SiC substrates.
In one embodiment of the present utility model, the SiC substrate 11 is N-type or P type substrate.
In one embodiment of the present utility model, the SiC substrate 11 includes N-type region and the p type island region of heavy doping.
In one embodiment of the present utility model, the doped source of the N-type region is Al, doping concentration is 1.0 ×
1020cm-3。
In one embodiment of the present utility model, the doped source of the p type island region is N, and doping concentration is 3.0 × 1020cm-3。
In one embodiment of the present utility model, the thickness of the first Ni layers 12 isThe thickness of Ti layers 13 isThe thickness of 2nd Ni layers 14 isThe TaSi2Layer 15 thickness beAnd the thickness of Pt layers 16
For
Compared with prior art, the utility model provides a kind of Pt/TaSi2/ Ni/Ti/Ni/SiC ohmic contact structures,
This arrangement enhances the heat endurance of Ohmic contact and antioxygenic property.
Brief description of the drawings
It is required in being described below to embodiment in order to illustrate more clearly of the technical scheme of the utility model embodiment
The accompanying drawing used is briefly described, it should be apparent that, drawings in the following description are only some implementations of the present utility model
Example, for those of ordinary skill in the art, on the premise of not paying creative work, can also be obtained according to these accompanying drawings
Obtain other accompanying drawings.
Fig. 1 is a kind of SiC ohmic contact section of structure that the utility model embodiment provides；
Fig. 2 is the XRD elemental maps before and after a kind of Pt/Ti/SiC structures annealing that the utility model embodiment provides；
Fig. 3 is the scanning electron microscope image of device surface after a kind of annealing that the utility model embodiment provides；
Fig. 4 is a kind of Pt/TaSi that the utility model embodiment provides2The front and rear XRD of/Ni/Ti/Ni/SiC structures annealing
Elemental map；
Fig. 5 is a kind of Pt/TaSi that the utility model embodiment provides2/ Ni/Ti/Ni/SiC, Ti/Pt structures N, p-type Europe
Nurse contacts the I-V curve figure after 975 DEG C of annealing；
Fig. 6 is a kind of Pt/TaSi that the utility model embodiment provides2/ Ni/Ti/Ni/SiC, Ti/Pt structures N, p-type Europe
Nurse contact characteristic conducting resistance with ageing time change curve；
Fig. 7 is a kind of CTLM structures domain that the utility model embodiment provides；
Fig. 8 is metal structure microscope photograph after a kind of stripping that the utility model embodiment provides.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the embodiment of the utility model is carried out
Clearly and completely describing, it is clear that described embodiment is only the utility model part of the embodiment, rather than whole
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment obtained, belong to the scope of the utility model protection.
Embodiment one
Fig. 1 is referred to, Fig. 1 is a kind of SiC ohmic contact section of structure that the utility model embodiment provides, including：
SiC substrate 11；
First Ni layers 12, it is arranged in the SiC substrate 11；
Ti layers 13, it is arranged on the first Ni layers 12；
2nd Ni layers 14, it is arranged on the Ti layers 13；
TaSi2Layer 15, is arranged on the 2nd Ni layers 14；
Pt layers 16, it is arranged at the TaSi2On layer 15.
Preferably, the SiC substrate 11 is 4H-SiC substrates or 6H-SiC substrates.
Further, the SiC substrate 11 is N-type or P type substrate.
Preferably, the SiC substrate 11 can include n-type doping area and the p-type doped region that horizontal direction is arranged in order.
Preferably, the SiC substrate 11 can also include n-type doping area or p-type doped region.
Wherein, the doped source in the n-type doping area is Al, and doping concentration is 1.0 × 1020cm-3；The p-type doped region
Doped source is N, and doping concentration is 3.0 × 1020cm-3。
Preferably, the thickness of the first Ni layers 12 isThe thickness of Ti layers 13 isThe 2nd Ni layers
14 thickness areThe TaSi2Layer 15 thickness beAnd the thickness of Pt layers 16 is
Wherein, the first Ni layers and SiC produce reaction, and Ti layers can combine C, Yi Mianyou caused by Ni and SiC reacts
The C atoms of amorph gather on surface, and make rough surface or failure.As shown in Fig. 2 Fig. 2 carries for the utility model embodiment
XRD elemental maps before and after a kind of Pt/Ti/SiC structures annealing supplied, Ti ratio significantly reduces after annealing, and TiC alloy ratios
It is obvious to rise.
2nd Ni layers are as Ti layers and TaSi2Adhesion layer between layer, can effectively reduce annealing temperature, to carry out simultaneously
The annealing of N/P types, while it can improve contact surface complexion；As shown in figure 3, Fig. 3 is one that the utility model embodiment provides
The scanning electron microscope image of device surface after kind annealing, it can be seen that Ni layers also serve stop to diffusing up for Ti
Effect.
Further, TaSi2Layer is the key for preventing Ohm contact electrode from aoxidizing, and it can effectively stop that O spreads downwards,
At 500 DEG C, after carrying out 300h annealing conditions in air, TaSi2The following O of layer ratio does not increase, shows TaSi2Layer is to O's
Barrier effect is notable.In addition, TaSi2Decomposition index of coincidence form enable this structure for a long time effectively, therefore, order
This structure can expose carries out burn-in test in atmosphere.As shown in figure 4, Fig. 4 is one kind that the utility model embodiment provides
Pt/TaSi2The front and rear XRD elemental maps of/Ni/Ti/Ni/SiC structures annealing, each element keep original alloy structure substantially, i.e.,
TaSi2Slow decomposition each metal-layer structure is remained unchanged substantially.
Simple Ni/Pt, Ti/Pt structure fails under high temperature air environment in the short time in the utility model.Ni/
TaSi2/Pt、Ti/TaSi2/ Pt structures are difficult to form good p-type Ohm contact electrode.Pt/TaSi2/ Ni/Ti/Ni/SiC is tied
Structure realizes N, the ohmic contact characteristic in substrate P, the Ti/Pt more excellent compared to performance in the range of vacuum or inertia knots simultaneously
Structure, its characteristic is as shown in figure 5, Fig. 5 is a kind of Pt/TaSi that the utility model embodiment provides2/Ni/Ti/Ni/SiC、Ti/Pt
I-V curve figure after 975 DEG C of structure N, p-type Ohmic contact annealing；Ohmic contact characteristic is good.This structure is entered in atmosphere
Row high temperature, burn-in test, do not occur seriously degenerating at 300 hours.Meanwhile as shown in fig. 6, Fig. 6 is implemented for the utility model
A kind of Pt/TaSi that example provides2When/Ni/Ti/Ni/SiC, Ti/Pt structures N, p-type Ohmic contact specific on-resistance are with aging
Between change curve；In room temperature with 500 DEG C of hot conditions, measuring its specific on-resistance and being compared with Ti/Pt structures.I.e.
Pt/TaSi2/ Ni/Ti/Ni/SiC has superperformance under high temperature, aging condition, and remaining structure has very big in contrast to more than
Advantage.
Embodiment two
The present embodiment is on the basis of above-described embodiment, to the preparation method of the SiC ohmic contact structure of above-described embodiment
It is described in detail, the SiC ohmic contact structure includes：SiC substrate, and be set in turn in the SiC substrate
One Ni layers, Ti layers, the 2nd Ni layers, TaSi2Layer and Pt layers；
Specifically, the preparation method includes：
S201,4H-SiC substrates are chosen, standard RCA clean is carried out to 4H-SiC substrates；
S202, it is 100nmSiO in 4H-SiC substrates deposition thickness using pecvd process2Oxide layer；
S203, etching oxidation layer forms ion implanting window, to 4H-SiC substrates N+Or P+Ion implanting, formed highly doped
Miscellaneous N areas or P areas simultaneously carry out high annealing；
S204, etch remaining oxide layer；
S205, the deposited metal on 4H-SiC substrates, metal level include the first Ni layers, Ti layers, the successively from lower to upper
Two Ni layers, TaSi2Layer and Pt layers；
S206, short annealing is to form Ohmic contact.
Preferably, the doped source in n-type doping area described in step S203 is Al, and doping concentration is 1.0 × 1020cm-3；Institute
The doped source for stating p-type doped region is N, and doping concentration is 3.0 × 1020cm-3.The temperature for carrying out high annealing is 1700 DEG C, the time
For 30min.
Preferably, in step S205, in used deposition process, the first Ni layers, Ti layers, the 2nd Ni layers and Pt layers use
Magnetically controlled DC sputtering deposits；TaSi2Layer is deposited using rf magnetron sputtering；
First Ni layers, Ti layers, the deposit power of the 2nd Ni layers and Pt layers are 100W；TaSi2The deposit power of layer is 60W；
Ti layers, TaSi2The deposition rate of layer and Pt layers is 2.9nm/min, the first Ni layers and the 2nd Ni layers deposition rate
For 9.8nm/min；Intracavitary vacuum≤5e when deposit-6mTorr；
The deposit throughput of first Ni layers and the 2nd Ni layers is 24Ar/sccm, and the deposit throughput of Ti layers and Pt layers is
16Ar/sccm, TaSi2The deposit throughput of layer is 20Ar/sccm.
Further, the first Ni thickness degree be 30nm, Ti thickness degree be 100nm, the 2nd Ni thickness degree be 30nm, TaSi2
Thickness degree is that 300nm and Pt thickness degree is 200nm.
Wherein, the method that performance test is carried out to the ohmic contact structure in the present embodiment is as follows：
Step 1：4H-SiC substrates are chosen, standard RCA clean is carried out to 4H-SiC substrates；
Step 2：It is 100nmSiO in 4H-SiC substrates deposition thickness using pecvd process2Oxide layer；
Step 3：Etching oxidation layer forms ion implanting window, to 4H-SiC substrates N+Or P+Ion implanting, formed high
The N areas or P areas of doping simultaneously carry out high annealing；
Step 4：Photoetching is carried out using mask plate, forms CTLM figures, primer is removed, removing natural oxidizing layer is removed using HF
And other impurities.
Further, CTLM figures are formed in step 4 as shown in fig. 7, Fig. 7 is one that the utility model embodiment provides
Kind CTLM structure domains；
Preferably, HF proportionings are HF in step 4：H2O=1：20.2min is embathed in HF, is washed off afterwards with clear water
HF solution, N2Drying.
Step 5：Deposit the first Ni layers, Ti layers, the 2nd Ni layers, TaSi successively in SiC material2Layer and Pt layers；
Step 6：Metal-stripping forms ohmic contact structure with short annealing and carries out performance to the ohmic contact structure
Test.
Further, metal-stripping concretely comprises the following steps in step 6：The whole lining of 4H-SiC substrates and metal level will be included
Bottom material, which is placed in acetone, to be soaked about 10h metal level tilts to photoresist layer, carries out ultrasound about 3min afterwards to tilting metal
Completely fall off.As shown in figure 8, metal structure microscope photograph after a kind of stripping that Fig. 8, which is the utility model embodiment, to be provided；
Observation becket does not have adhesion under the microscope.The condition of annealing is 975 DEG C of temperature, in the protection atmosphere of inert gas, annealing
Time 2min.
The utility model utilizes Pt/TaSi2/ Ni/Ti/Ni/SiC structure fabrication SiC ohmic contacts.First, Ni and SiC is anti-
Should.Ti layers can with reference to due to Ni and SiC reaction caused by C, in order to avoid the C atoms of free state gather on surface, and make surface thick
Rough or failure.Ti ratio significantly reduces after annealing, and TiC alloy ratios substantially rise.2nd Ni layers are as Ti metal levels
With TaSi2Adhesion layer between metal level, annealing temperature can be effectively reduced, to carry out the annealing of N/P types, while its energy simultaneously
Contact surface complexion is improved, and this nickel dam also serves barrier effect to diffusing up for Ti.TaSi2Layer is to prevent ohm from connecing
The key of touched electrode oxidation, it can effectively stop that O spreads downwards, after 300h burn-in tests, TaSi2The following O of layer ratio
Do not increase, show TaSi2Layer is notable to O barrier effect.
To sum up, specific case used herein is set forth to principle of the present utility model and embodiment, the above
The explanation of embodiment is only intended to help and understands method and its core concept of the present utility model；Meanwhile for the one of this area
As technical staff, according to thought of the present utility model, there will be changes, comprehensive in specific embodiments and applications
On, this specification content should not be construed as should be with appended power to limitation of the present utility model, the scope of protection of the utility model
Profit requires to be defined.
Claims (7)
- A kind of 1. SiC ohmic contact structure, it is characterised in that including：SiC substrate (11)；First Ni layers (12), it is arranged in the SiC substrate (11)；Ti layers (13), it is arranged on the first Ni layers (12)；2nd Ni layers (14), it is arranged on the Ti layers (13)；TaSi2Layer (15), is arranged on the 2nd Ni layers (14)；Pt layers (16), are arranged at the TaSi2On layer (15).
- 2. SiC ohmic contact structure according to claim 1, it is characterised in that the SiC substrate (11) serves as a contrast for 4H-SiC Bottom or 6H-SiC substrates.
- 3. SiC ohmic contact structure according to claim 1, it is characterised in that the SiC substrate (11) is N-type or P Type substrate.
- 4. SiC ohmic contact structure according to claim 1, it is characterised in that the SiC substrate (11) includes heavy doping N-type region or p type island region.
- 5. SiC ohmic contact structure according to claim 4, it is characterised in that the doped source of the N-type region is Al, is mixed Miscellaneous concentration is 1.0 × 1020cm-3。
- 6. SiC ohmic contact structure according to claim 4, it is characterised in that the doped source of the p type island region is N, doping Concentration is 3.0 × 1020cm-3。
- 7. SiC ohmic contact structure according to claim 1, it is characterised in that the first Ni layers (12) thickness isTi layers (13) thickness is2nd Ni layers (14) thickness isThe TaSi2Layer (15) is thick Spend and beAnd Pt layers (16) thickness is
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109087850A (en) * | 2018-06-20 | 2018-12-25 | 中国电子科技集团公司第五十五研究所 | Surface of SiC Ohmic contact optimization method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109087850A (en) * | 2018-06-20 | 2018-12-25 | 中国电子科技集团公司第五十五研究所 | Surface of SiC Ohmic contact optimization method |
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