CN206907771U - High-temperature resistant silicon carbide ohmic contact structure - Google Patents

Abstract

A kind of high-temperature resistant silicon carbide ohmic contact structure is the utility model is related to, including：SiC substrate (10), SiC epitaxial layer (20) and the Ni metal levels (30), W metal levels (40), TaSi that are set in turn in the SiC epitaxial layer surface₂Metal level (50), Pt metal levels (60).High-temperature resistant silicon carbide ohmic contact structure provided by the utility model has good thermal stability and electrology characteristic under high temperature, air ambient.

Description

High-temperature resistant silicon carbide ohmic contact structure

Technical field

The utility model category silicon carbide device manufacturing field, more particularly to a kind of high-temperature resistant silicon carbide ohmic contact structure.

Background technology

Compared to traditional germanium, silicon materials, the advantage of third generation wide band gap semiconducter carborundum mainly includes：Electric field is born Ability is about ten times of silicon materials, and energy gap is about three times of silicon materials, and thermal conductivity factor is about silicon materials three times etc..Above material Characteristic causes it to show under the conditions of extreme temperature (especially high temperature) and big voltage, high-frequency and high power and intense radiation etc. The incomparable advantage of traditional silicon-based devices.

Ohmic contact is one of key influence factor that silicon carbide device is applied in the extreme environment such as high temperature, oxidizable, Its 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 device Performance.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, carborundum metal ohmic contact or alloy-layer Problems are weak including oxidation resistance, are in atmosphere It is oxidized；Heat endurance is poor, occurs degenerating under high temperature or fails；Hardness is low, easily by mechanical damage the shortcomings of, these shortcomings The reduction of Ohm contact electrode reliability can be caused, seriously limit its application environment and scope, and then make the application of silicon carbide device Scope is with reliability by many influences and limitation.

Utility model content

In view of background above, the utility model aims at a kind of high-temperature resistant silicon carbide ohmic contact structure.

Specifically, a kind of high-temperature resistant silicon carbide ohmic contact structure that the utility model one embodiment proposes, including SiC Substrate 10, SiC epitaxial layer 20 and be set in turn in the Ni metal levels 30 on the surface of SiC epitaxial layer 20, W metal levels 40, TaSi₂Metal level 50, Pt metal levels 60.

In one embodiment of the present utility model, the material of the SiC substrate 10 is 4H-SiC.

In one embodiment of the present utility model, N areas or P areas are provided with the SiC epitaxial layer 20.

In one embodiment of the present utility model, the dopant species in the N areas are Al, correspondingly, the doping in the P areas Species is N.

In one embodiment of the present utility model, the thickness of the Ni metal levels 30 is

In one embodiment of the present utility model, the thickness of the W metal levels 40 is

In one embodiment of the present utility model, the TaSi₂The thickness of metal level 50 is

In one embodiment of the present utility model, the thickness of the Pt metal levels 60 is

Compared with prior art, the utility model provides a kind of Pt/TaSi₂Carborundum ohm of/W/Ni/SiC structures Electrode is contacted, the structure ensure that the good electrology characteristic of Ohm contact electrode and heat endurance.

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 carborundum ohmic contact structure schematic diagram that the utility model embodiment provides；

Fig. 2 is a kind of CTLM structures domain that the utility model embodiment provides；

Fig. 3 is microscope photograph after a kind of metal-stripping that the utility model embodiment provides；

Fig. 4 be the utility model embodiment provide a kind of carborundum ohmic contact structure annealing after with after aging 300h often Warm condition and the I-V curve figure under hot conditions；

Fig. 5 is a kind of carborundum ohmic contact structure specific contact resistivity of the utility model embodiment offer with ageing time Change curve；

Fig. 6 is that a kind of carborundum ohmic contact structure that the utility model embodiment provides completes surface scan electricity after annealing Sub- MIcrosope image；

Fig. 7 is a kind of carborundum ohmic contact structure of the utility model embodiment offer in air at a temperature of 500 DEG C After carrying out 300h aging conditions, surface Scanning Electron MIcrosope image.

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 carborundum ohmic contact structure schematic diagram that the utility model embodiment provides, should Electrode structure includes：SiC substrate 10, SiC epitaxial layer 20 and the Ni metal levels for being set in turn in the surface of SiC epitaxial layer 20 30th, W metal levels 40, TaSi₂Metal level 50, Pt metal levels 60.

Further, the material of the SiC substrate 10 is 4H-SiC.

Further, N areas or P areas are provided with the SiC epitaxial layer 20.

Further, the doping concentration in the N areas is 1.0 × 10¹⁹cm^-3, correspondingly, the doping concentration in the P areas is 1.3×10²⁰cm^-3。

Further, the dopant species in the N areas are Al, and correspondingly, the dopant species in the P areas are N.

Further, the thickness of the Ni metal levels 30 is

Further, the thickness of the W metal levels 40 is

Further, the TaSi₂The thickness of metal level 50 is

Further, the thickness of the Pt metal levels 60 is

Compared with prior art, high-temperature resistant silicon carbide ohmic contact structure provided by the utility model, i.e. Pt/TaSi2/W/ Ni/SiC structures, there is superperformance under high temperature, air ambient, being applied under high temperature, air ambient has very big advantage.

Embodiment two

The preparation method that the present embodiment will introduce high-temperature resistant silicon carbide ohmic contact structure in more detail.This method is specific Step is：

Step 1：4H-SiC substrates are chosen, standard RCA clean is carried out to 4H-SiC substrates；

Step 2：SiC epitaxial layer is grown in 4H-SiC substrate surfaces, standard RCA clean is carried out to SiC epitaxial layer；

Step 3：Utilize vapour deposition process (the Plasma Enhanced Chemical Vapor of plasma enhanced chemical Deposition, PECVD) technique, form the thick SiO of ion implanting 100nm in SiC epitaxial layer₂Layer；

Step 4：The SiO is etched using etching technics₂Layer, N is carried out to the SiC epitaxial layer⁺Ion or P⁺Ion is noted Enter, form highly doped N areas or P areas；

Preferably, n-type doping concentration is 1.0 × 10¹⁹cm^-3, dopant species Al；P-type doping concentration be 1.3 × 10²⁰cm^-3, dopant species N.

Step 5：The remaining SiO is etched using etching technics₂Layer, and carry out high annealing；

Preferably, the temperature of high annealing is 1700 DEG C, and the time is 30 minutes.

Step 6：Ni metal levels, W metal levels, TaSi are deposited successively in SiC epitaxial layer₂Metal level and Pt metal levels, specifically It is as follows：

It is in SiC epitaxial layer surface deposition Ni metal levels, the thickness of Ni metal levels using DC magnetron sputtering processDeposit power is 100w, deposition rate 9.8nm/min, throughput 24Ar/sccm, intracavitary vacuum are≤5e^-6mTorr；

W metal levels are deposited in Ni layer on surface of metal using DC magnetron sputtering process, the thickness of W metal levels isForm sediment Product power is 100w, deposition rate 8.9nm/min, throughput 16Ar/sccm, intracavitary vacuum are≤5e^-6mTorr；

Using rf magnetron sputtering technique TaSi is deposited in W layer on surface of metal₂Metal level, TaSi₂The thickness of metal level isDeposit power is 60w, deposition rate 2.9nm/min, throughput 20Ar/sccm, intracavitary vacuum are≤5e^{- 6}mTorr；

Using DC magnetron sputtering process in TaSi₂Layer on surface of metal deposits Pt metal levels, and the thickness of Pt metal levels isDeposit power is 100w, deposition rate 2.9nm/min, throughput 16Ar/sccm, intracavitary vacuum are≤5e^-6mTorr。

Step 7：By Ni metal levels, W metal levels, TaSi₂Metal level, the progress short annealing of Pt metal levels are described resistance to complete The making of high-temperature carborundum Ohm contact electrode.

Wherein, the method that performance test is carried out to the high-temperature resistant silicon carbide 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：SiC epitaxial layer is grown in 4H-SiC substrate surfaces, standard RCA clean is carried out to SiC epitaxial layer；

Step 3：Utilize vapour deposition process (the Plasma Enhanced Chemical Vapor of plasma enhanced chemical Deposition, PECVD) technique, form the thick SiO of ion implanting 100nm in SiC epitaxial layer₂Layer；

Step 4：N is carried out to SiC epitaxial layer using ion implantation technology⁺Ion or P⁺Ion implanting, form highly doped N Area or P areas simultaneously carry out high annealing；

Preferably, n-type doping concentration is 1.0 × 10¹⁹cm^-3, dopant species Al；P-type doping concentration be 1.3 × 10²⁰cm^-3, dopant species N；

Preferably, the temperature of high annealing is 1700 DEG C, and the time is 30 minutes.

Step 5：In SiO₂Layer surface deposits photoresist, carries out photoetching using mask plate, forms round coal storage yard (circular transmission line model, abbreviation CTLM) figure, as shown in Fig. 2 Fig. 2 is implemented for the utility model A kind of CTLM structures domain that example provides；Then photoresist is removed, and the SiO under CTLM figures is removed using HF₂Layer and other Impurity；

Preferably, HF proportionings are HF：H₂O=1：20.Embathed in HF 2 minutes, wash off HF solution with clear water afterwards, N₂Drying.

Step 6：Using magnetron sputtering technique in SiC epitaxial layer and photoresist surface deposition metal level, metal level from it is lower toward On be including thickness successivelyNi metal levels, thickness beW metal levels, thickness beTaSi₂Gold Category layer and thickness arePt metal levels；

Preferably, Ni metal levels, W metal levels and Pt metal levels are deposited using DC magnetron sputtering process, TaSi₂Metal level Deposited using rf magnetron sputtering technique；

The deposit power of metal level is respectively：The Ni metal levels, the W metal levels and the Pt metal levels are 100w, The TaSi₂Metal level is 60w；

The deposition rate of metal level is respectively：The W metal levels are 8.9nm/min, Pt metal levels and the TaSi₂Metal Layer is 2.9nm/min, and the Ni metal levels are 9.8nm/min；

Intracavitary vacuum≤5e of the magnetron sputtering technique^-6mTorr；

The throughput of the magnetron sputtering technique is respectively：The Ni metal levels are 24Ar/sccm, the W metal levels and The Pt metal levels are 16Ar/sccm, the TaSi₂Metal level is 20Ar/sccm.

Step 7：Metal-stripping and short annealing are to form ohmic contact structure and carry out performance test.

Preferably, the whole material including 4H-SiC substrates, SiC epitaxial layer and metal level is placed in acetone and soaks about 10 Hour to metal level on photoresist layer (i.e. Ni metal levels, W metal levels, TaSi₂Metal level and Pt metal levels) tilt, carry out afterwards Ultrasound about 3min is completely fallen off to metal is tilted.A kind of as shown in figure 3, metal stripping that Fig. 3, which is the utility model embodiment, to be provided From microscope photograph afterwards；Observation becket does not have adhesion under the microscope.The condition of annealing is 975 DEG C of temperature, inert gas Protection atmosphere in, anneal 1 minute.

The utility model utilizes carborundum ohmic contact structure (i.e. Pt/TaSi₂/ W/Ni/SiC structures) make SiC ohms Contact.First, Ni and SiC reacts.W layers can with reference to caused by due to Ni and SiC reactions C, in order to avoid the C atoms of free state are in table Face is gathered, and makes rough surface or failure.

In the utility model, TaSi₂Layer is the key for preventing Ohm contact electrode from aoxidizing, layer on surface of metal in annealing process Generate PtSi₂Layer, PtSi₂There is stronger combination O ability, effective delayed-action is served for diffusions of the O to interface. TaSi₂Decomposition index of coincidence form enable this structure for a long time effectively, TaSi₂Slow decomposition cause each metal level knot Therefore structure remains unchanged substantially, this structure can be made to expose and carry out burn-in test in atmosphere.

In the utility model, TaSi₂Layer can produce small hole in annealing process, and then it can be caused in high temperature, sky When in compression ring border, lower metal of the metal structure at 50 hours initial holes is oxidized, and specific contact resistivity declines.So draw Enter to be not easy oxidized metal level tungsten to prevent specific contact resistivity from increasing.

In the utility model, Pt/TaSi₂/ W/Ni/SiC structures realize N, the Ohmic contact of p-type simultaneously, to this structure High temperature, burn-in test are carried out in atmosphere, and electrology characteristic does not change substantially at 300 hours.Meanwhile in room temperature and 500 DEG C of height Under the conditions of temperature, its I-V characteristic curve is measured, as shown in figure 4, Fig. 4 is a kind of carborundum Europe that the utility model embodiment provides After the annealing of nurse contact structures with the I-V curve figure under normal temperature condition after aging 300h and hot conditions.As shown in figure 5, Fig. 5 is this Utility model embodiment provide a kind of carborundum ohmic contact structure specific contact resistivity with ageing time change curve, from Change of the specific contact resistivity with ageing time is can be seen that in Fig. 5, illustrates the stable electricity of metal structure of the present utility model Characteristic.

Fig. 6 and Fig. 7, Fig. 6 visible with the surface comparison diagram after aging are that the utility model is real after being annealed in the utility model A kind of carborundum ohmic contact structure for applying example offer completes surface Scanning Electron MIcrosope image after annealing；Fig. 7 is this practicality After a kind of carborundum ohmic contact structure that new embodiment provides carries out 300h aging conditions in air at a temperature of 500 DEG C, Surface Scanning Electron MIcrosope image.The surface complexion of Ohmic contact is bonded for device wire and specific contact resistivity value has Significantly affect, can see in Fig. 6 and Fig. 7, under air ambient after aging 300 hours, the surface of this metal structure is still very Smoothly.

That is Pt/TaSi₂/ W/Ni/SiC has superperformance under high temperature, air ambient, should under high temperature, air ambient With there is very big advantage.

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 (8)

1. A kind of 1. high-temperature resistant silicon carbide ohmic contact structure, it is characterised in that including：SiC substrate (10), SiC epitaxial layer (20) And it is set in turn in the Ni metal levels (30), W metal levels (40), TaSi on the SiC epitaxial layer (20) surface₂Metal level (50), Pt metal levels (60).
2. 2. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the SiC substrate (10) Material be 4H-SiC.
3. 3. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the SiC epitaxial layer (20) N areas or P areas are provided with.
4. 4. high-temperature resistant silicon carbide ohmic contact structure according to claim 3, it is characterised in that the doping kind in the N areas Class is Al, and correspondingly, the dopant species in the P areas are N.
5. 5. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the Ni metal levels (30) Thickness be
6. 6. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the W metal levels (40) Thickness be
7. 7. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the TaSi₂Metal level (50) thickness is
8. 8. high-temperature resistant silicon carbide ohmic contact structure according to claim 1, it is characterised in that the Pt metal levels (60) Thickness be