CN104037075A - Thermal-resistance-processed silicon carbide back metal thickening method - Google Patents

Thermal-resistance-processed silicon carbide back metal thickening method Download PDF

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Publication number
CN104037075A
CN104037075A CN201410259946.XA CN201410259946A CN104037075A CN 104037075 A CN104037075 A CN 104037075A CN 201410259946 A CN201410259946 A CN 201410259946A CN 104037075 A CN104037075 A CN 104037075A
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metal
thickening
sic
carborundum
high temperature
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CN104037075B (en
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陶永洪
柏松
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CETC 55 Research Institute
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture 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
    • H01L21/0445Manufacture 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
    • H01L21/048Making electrodes
    • H01L21/0485Ohmic electrodes
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture 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
    • H01L21/0445Manufacture 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
    • H01L21/045Manufacture 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 passivating silicon carbide surfaces

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Electrodes Of Semiconductors (AREA)

Abstract

The invention relates to a thermal-resistance-processed silicon carbide back metal thickening method. The method comprises the following steps of 1) forming a metal layer on the back surface of a SiC wafer through evaporation or sputtering, and forming an ohmic contact after an annealing process; forming a stopping metal layer on the back surface ohmic contact through evaporation or sputtering; 3) applying a layer of resin onto the front surface of the SiC wafer, heating the SiC wafer in a drying oven to solidify the resin; 4) performing coating protection, wet HF corrosion, cleaning and drying on the front surface of the SiC wafer; 5) forming thickening metal on the back surface of the SiC wafer through sedimentation; 6) performing photoresist removal and scribing, and after a chip is sintered onto a carrier, performing shear assessment. The thermal-resistance-processed silicon carbide back metal thickening method has the advantages of solving the problem of infirmness of the back surface metal of a high-temperature-processed SiC power device, and by means of the stopping metal layer sputtered onto the back surface ohmic contact, which can be diffused to combine with C on the surface of the ohmic contact after the high-temperature processing process, avoiding forming a dissociative C layer and guaranteeing the firmness and reliability of the back surface thickening metal.

Description

The carborundum back metal thickening method of high temperature resistant processing
Technical field
What the present invention relates to is a kind of back metal thickening method, and what be specifically related to is a kind of carborundum back metal thickening method of high temperature resistant processing.
Background technology
Carborundum (SiC) material because thering is large energy gap (3.2eV), high critical breakdown electric field (reaches 4 × 10 6more than V/cm), high electron saturation velocities (2 × 10 7and the performance such as high thermal conductivity (4.9W/cm.K) cm/s), under the conditions of work such as high temperature, high-power, anti-irradiation, there is obvious advantage, have broad application prospects in fields such as communication, traffic, the energy.
In silicon carbide power device, conventionally adopt nickel (Ni) as metal ohmic contact, in the carborundum disk surfaces extension that a floor height mixes of growing, after precipitation metallic nickel, through up to 1000 oafter the high annealing of C, form good ohmic contact, it connects specific contact resistivity rate can reach 1 Х 10 -6 ?.cm 2.But, in the ohmic contact forming process of carborundum, due to nickel and silicon carbide reactor formation nisiloy compound (Ni xsi y), will separate out carbon (C), in ohm annealing process, because the high annealing time is shorter, carbon is not also diffused into surface, due to diffusion coefficient and time and the temperature relation in direct ratio of carbon, under the higher temperatures long period, this carbon will be diffused into ohmic contact surface, forms free carbon-coating, at this time carry out again metal process for upsetting, very poor of the adhesiveness that can cause thickening metal.
For appeal problem, conventionally can remove the carbon that the back side separates out by wet etching and dry etching, the strong acid meeting corrosion device front that wherein wet etching is used, dry method is carved the carborundum back side, can pollute silicon carbide wafer and etching apparatus cavity, and this two method all can be damaged the electrical property of silicon carbide device, and produce reliability hidden danger, therefore, need not remove carbon-coating, the carborundum back metal process for upsetting of back metal good adhesion exploitation is simultaneously very important.
Summary of the invention
The carborundum back metal thickening method of a kind of high temperature resistant processing that the present invention proposes, its objective is and solve the existing above-mentioned deficiency of existing technique, hold onto the carbon dissociating out after high-temperature process by the method for alloy, when not affecting device electric property, improve the silicon carbide device back side thickening adhesiveness of metal and the reliability of device.
Technical solution of the present invention comprises the following steps:
1), in the evaporation of SiC chip back surface or sputter layer of metal, after annealing, form ohmic contact;
2) in ohmic contact, evaporate or sputter one deck barrier metal overleaf;
3) be coated with the resin of one deck for high voltage protective at SiC front wafer surface, solidify through baking oven high-temperature baking;
4) SiC front wafer surface Coating glue protect, wet method HF corrosion, cleans and dries;
5) at SiC chip back surface precipitation thickening metal;
6) scribing of removing photoresist, does shearing force assessment.
Beneficial effect of the present invention: the method has solved by carborundum back side ohmic contact after high-temperature process and separated out the metal adhesion problem that free carbon-coating causes, do not need to adopt wet etching or dry etch process simultaneously, technique is simple, pollutes without technique, has reduced process costs; The device that adopts the carborundum back metal thickening method development of this high temperature resistant processing, electric property and reliability are good, back metal good adhesion and high temperature resistant processing.
Brief description of the drawings
Accompanying drawing 1 is SiC disk schematic diagram.
Accompanying drawing 2 is that the generalized section after ohmic contact has been done at the SiC disk back side.
Accompanying drawing 3 is to precipitate the generalized section after one deck barrier metal in the ohmic contact of the SiC disk back side.
Accompanying drawing 4 is the positive generalized sections that are coated with after one deck resin of SiC disk.
Accompanying drawing 5 is the generalized sections after the Coating glue protect of SiC disk front.
Accompanying drawing 6 is that back metal is thickeied later generalized section.
Embodiment
The carborundum back metal thickening method of high temperature resistant processing, the method comprises the following steps:
1), in the evaporation of SiC chip back surface or sputter layer of metal, after annealing, form ohmic contact;
2) in ohmic contact, evaporate or sputter one deck barrier metal overleaf;
3) be coated with one deck resin, baking oven high-temperature baking cured resin at SiC front wafer surface;
4) SiC front wafer surface Coating glue protect, wet method HF corrosion, cleans and dries;
5) at SiC chip back surface precipitation thickening metal;
6) scribing of removing photoresist, chip does shearing force assessment after being sintered on carrier.
The described Ni metal at the evaporation of SiC chip back surface or sputter layer of metal 100nm, 1000 oafter C annealing 10min, form good ohmic contact; The Ni metal of 100nm, in high temperature rapid thermal annealing, all reacts with SiC, and the Ni that top layer does not have and SiC reacts is also dense, has stopped separating out of carbon, has the carbon of blackout to separate out, as shown in Figure 2 so now do not observe the back side.
In described ohmic contact overleaf, sputter one deck barrier metal comprises W, Ti, and WTi, WiTiAuTi, thickness is 10nm~300nm, adopts the mode of evaporation or sputter to form, as shown in Figure 3.
Described is the thick resin bed of 4 μ m at SiC front wafer surface painting one deck resin, and baking oven heating-up temperature is since 25 DEG C, and multistage 2h is heated to 400 DEG C, then, after 400 DEG C of constant temperature 2h, cools to room temperature; After time high-temperature process, carbon has diffused into barrier metal layer, is combined with W, Ti or its alloy, has prevented the diffusion of carbon to metal surface, avoids forming on surface free carbon-coating, the adhesiveness of impact thickening metal, as shown in Figure 4.
Described SiC front wafer surface Coating glue protect, wet method HF corrosion, is that quality matched proportion density is 20% HF% processing 1min, as shown in Figure 5.
Described is after step 4) at SiC chip back surface precipitation thickening metal, the thickening metal of back side evaporation, sputter or plating 1 μ m~6 μ m, and back side thickening metal comprises Au, Ag, NiAu, NiAg, TiNiAu, TiNiAg; Scribing after removing photoresist, as shown in Figure 6.
Described back side ohmic metal also comprises Ni, Ti, and Gr, Mo, W and alloy thereof, annealing temperature is 600 oc~1100 oc.
Sputter one deck barrier metal on the ohm of the described back side, this barrier metal comprises W, Ti, WTi, WiTiAuTi, thickness is 10nm~300nm, adopts the mode of evaporation or sputter to form.
Described at SiC front wafer surface painting one deck resin, resin bed is benzocyclobutene (BCB) or polyimides, and baking oven baking temperature is 100 oc~500 oc, baking time is 1h~12h.
The quality matched proportion density of described HF is 5%~10%, or 30%~50%, the time of processing is 10s~9min.

Claims (10)

1. the carborundum back metal thickening method of high temperature resistant processing, the method comprises the following steps:
1), in the evaporation of SiC chip back surface or sputter layer of metal, after annealing, form ohmic contact;
2) in ohmic contact, evaporate or sputter one deck barrier metal overleaf;
3) be coated with one deck resin, baking oven high-temperature baking cured resin at SiC front wafer surface;
4) SiC front wafer surface Coating glue protect, wet method HF corrosion, cleans and dries;
5) at SiC chip back surface precipitation thickening metal;
6) scribing of removing photoresist, chip does shearing force assessment after being sintered on carrier.
2. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, is characterized in that the described Ni metal at the evaporation of SiC chip back surface or sputter layer of metal 100nm, 1000 oafter C annealing 10min, form good ohmic contact; The Ni metal of 100nm, in high temperature rapid thermal annealing, all reacts with SiC, and the Ni that top layer does not have and SiC reacts is also dense, has stopped separating out of carbon, has the carbon of blackout to separate out so now do not observe the back side.
3. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, described in it is characterized in that, sputter one deck barrier metal comprises W, Ti in ohmic contact overleaf, WTi, WiTiAuTi, thickness is 10nm~300nm, adopts the mode of evaporation or sputter to form.
4. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, it is characterized in that described is the thick resin bed of 4 μ m at SiC front wafer surface painting one deck resin, baking oven heating-up temperature is since 25 DEG C, multistage 2h is heated to 400 DEG C, then after 400 DEG C of constant temperature 2h, cool to room temperature; After time high-temperature process, carbon has diffused into barrier metal layer, is combined with W, Ti or its alloy, has prevented the diffusion of carbon to metal surface, avoids forming on surface free carbon-coating, the adhesiveness of impact thickening metal.
5. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, is characterized in that described SiC front wafer surface Coating glue protect, and wet method HF corrosion is that quality matched proportion density is 20% HF% processing 1min.
6. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, it is characterized in that described is after step 4) at SiC chip back surface precipitation thickening metal, the thickening metal of back side evaporation, sputter or plating 1 μ m~6 μ m, back side thickening metal comprises Au, Ag, NiAu, NiAg, TiNiAu, TiNiAg; Scribing after removing photoresist.
7. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, is characterized in that described back side ohmic metal also comprises Ni, Ti, and Gr, Mo, W and alloy thereof, annealing temperature is 600 oc~1100 oc.
8. the carborundum back metal thickening method of high temperature resistant processing according to claim 1, is characterized in that sputter one deck barrier metal on the ohm of the described back side, and this barrier metal comprises W, Ti, WTi, WiTiAuTi, thickness is 10nm~300nm, adopts the mode of evaporation or sputter to form.
9. the carborundum back metal thickening method of high temperature resistant processing according to claim 4, is coated with one deck resin at SiC front wafer surface described in it is characterized in that, resin bed is benzocyclobutene or polyimides, and baking oven baking temperature is 100 oc~500 oc, baking time is 1h~12h.
10. the carborundum back metal thickening method of high temperature resistant processing according to claim 5, the quality matched proportion density that it is characterized in that described HF is 5%~10%, or 30%~50%, the time of processing is 10s~9min.
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CN105826167A (en) * 2015-01-23 2016-08-03 三菱电机株式会社 Substrate for semiconductor device and method of manufacturing same
CN107331606A (en) * 2017-05-09 2017-11-07 中国电子科技集团公司第五十五研究所 The preparation method of SiC device back metal system
CN109830456A (en) * 2018-12-25 2019-05-31 厦门市三安集成电路有限公司 The preparation method of method and power device that the back metal of power device thickeies
CN109994376A (en) * 2017-12-30 2019-07-09 无锡华润微电子有限公司 Ohmic contact structure formed in silicon carbide substrates and forming method thereof
CN113539800A (en) * 2021-06-10 2021-10-22 上海积塔半导体有限公司 Method for manufacturing semiconductor structure
CN113802184A (en) * 2021-08-25 2021-12-17 东莞市天域半导体科技有限公司 Method for quickly removing deposits on back of wafer in silicon carbide epitaxial process
CN113539800B (en) * 2021-06-10 2024-05-31 上海积塔半导体有限公司 Method for preparing semiconductor structure

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CN109994376A (en) * 2017-12-30 2019-07-09 无锡华润微电子有限公司 Ohmic contact structure formed in silicon carbide substrates and forming method thereof
CN109994376B (en) * 2017-12-30 2021-10-15 无锡华润微电子有限公司 Ohmic contact structure formed on silicon carbide substrate and forming method thereof
CN109830456A (en) * 2018-12-25 2019-05-31 厦门市三安集成电路有限公司 The preparation method of method and power device that the back metal of power device thickeies
CN113539800A (en) * 2021-06-10 2021-10-22 上海积塔半导体有限公司 Method for manufacturing semiconductor structure
CN113539800B (en) * 2021-06-10 2024-05-31 上海积塔半导体有限公司 Method for preparing semiconductor structure
CN113802184A (en) * 2021-08-25 2021-12-17 东莞市天域半导体科技有限公司 Method for quickly removing deposits on back of wafer in silicon carbide epitaxial process
CN113802184B (en) * 2021-08-25 2022-06-28 东莞市天域半导体科技有限公司 Method for quickly removing deposits on back of wafer in silicon carbide epitaxial process

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