CN115565856A - SiC power device ohmic contact, preparation method and application - Google Patents

SiC power device ohmic contact, preparation method and application Download PDF

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Publication number
CN115565856A
CN115565856A CN202211376435.7A CN202211376435A CN115565856A CN 115565856 A CN115565856 A CN 115565856A CN 202211376435 A CN202211376435 A CN 202211376435A CN 115565856 A CN115565856 A CN 115565856A
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sic
ohmic contact
substrate
power device
preparation
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Inventor
徐傲雪
田亮
仇坤
查祎英
王谦
史志扬
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Nanruilianyan Semiconductor Co ltd
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Nanruilianyan Semiconductor Co ltd
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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
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H01L29/1608Silicon carbide
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/40Electrodes ; Multistep manufacturing processes therefor
    • H01L29/401Multistep manufacturing processes
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/40Electrodes ; Multistep manufacturing processes therefor
    • H01L29/43Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/45Ohmic electrodes

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

Abstract

The invention discloses an ohmic contact of a SiC power device, a preparation method and application, comprising the steps of preprocessing the back surface of a 4H-SiC substrate, including the processes of etching and removing water vapor; preparing a material with a 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate; and finally, depositing a metal layer on the surface of the 3C-SiC crystal to prepare ohmic contact. The method simplifies the manufacturing process of ohmic contact, reduces specific contact resistance and power loss, and improves the reliability of the SiC power device.

Description

SiC power device ohmic contact, preparation method and application
Technical Field
The invention relates to ohmic contact of a SiC power device, a preparation method and application, and belongs to the technical field of semiconductor power devices.
Background
Since silicon devices are difficult to be applied in high-temperature, high-frequency, high-power and strong-radiation environments, electronic devices which can be applied in severe high-temperature radiation environments such as aerospace, oil exploration, nuclear energy, communication and the like are urgently needed, and a new generation of semiconductor materials is sought to become one of the hotspots of research in the field.
Silicon carbide is the third generation semiconductor material following silicon, germanium, gallium arsenide with its good physical and electrical properties. Commercial silicon carbide substrates and epitaxial materials were first reported since 1991, and significant progress was subsequently made in the process of fabricating silicon carbide devices. However, some key manufacturing process problems of the silicon carbide device still need to be solved and improved, wherein the ohmic contact is always the key and difficult point of the silicon carbide device preparation, the specific contact resistance determines the performance of the device, and the specific contact resistance has many influencing factors, such as the carrier concentration on the wafer surface, the type and thickness of the metal, the pretreatment on the wafer surface, the high-temperature annealing condition of the metal, and the like. In the prior art, ohmic contact is prepared on a silicon carbide power device, and is mainly formed by alloying and annealing a plurality of metals, so that the technical problems of large difference of process parameters, poor repeatability, complex and uncontrollable reaction mechanism exist.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides the ohmic contact of the SiC power device, the preparation method and the application thereof, so that the manufacturing process of the ohmic contact is simplified, the complexity of a metal annealing process is reduced, the specific contact resistance and the power loss are reduced, and the reliability of the SiC power device is improved.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a preparation method of ohmic contact of a SiC power device, which comprises the following steps:
carrying out pretreatment on the back of the 4H-SiC substrate, wherein the pretreatment comprises the processes of etching and removing water vapor;
preparing a material with a 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate;
and depositing a metal layer on the surface of the 3C-SiC crystal to prepare ohmic contact.
Further, the etching comprises the steps of treating the back surface of the silicon carbide substrate by using hydrofluoric acid and/or hydrochloric acid, removing oxide layer, organic matters and particle contamination on the back surface of the substrate, and then removing water vapor on the back surface of the substrate.
Further, the method for preparing the material with the 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate comprises the following steps:
at 0-100 deg.C, mixing at 5 × 10 18 ~5×10 20 cm -3 Al ions are injected into the back surface of the 4H-SiC substrate;
a carbon film sputtering device is adopted to sputter a carbon film with the thickness of 10nm to 30nm on the back of the 4H-SiC substrate after ions are injected;
performing activation annealing treatment on the 4H-SiC substrate with the carbon film sputtered on the back surface of the substrate at 1700-1900 ℃ for 3-10min to prepare a 3C-SiC crystal material;
oxidizing and removing the carbon film sputtered on the back of the 4H-SiC substrate;
putting the back surface of the 4H-SiC substrate with the carbon film removed into a high-temperature furnace for thermal oxidation of 500 to 800A, and then placing the substrate in CI 2 The RIE etching system of Ar gas performs etching.
Further, the method for preparing the material with the 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate comprises the following steps:
selecting monosilane or propane or ethylene as an epitaxial precursor, and selecting hydrogen and/or argon as a carrier gas to be introduced in advance, wherein the flow rate of the carrier gas is 300-600sccm;
in the chemical vapor deposition system, the epitaxial precursor deposits a 3C-SiC crystal structure with a thickness of 2-5 μm on the back of the pretreated 4H-SiC substrate.
Further, the deposition pressure in the chemical vapor deposition system is 800Pa-1400Pa, the growth temperature of the 3C-SiC crystal structure is 1500-1650 ℃, and the growth speed is 3-15 mu m/h.
Further, the method for preparing the material with the 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate comprises the following steps:
connecting the pretreated 4H-SiC substrate and the surface of the 3C-SiC wafer which needs to be bonded;
performing activation annealing at 1600-1900 ℃ in Ar atmosphere, and bonding the contact surface;
the unbonded surface of the 3C-SiC wafer is put into a high-temperature furnace for thermal oxidation 500A-800A, and then the surface is subjected to CI 2 And etching by using an RIE etching system of Ar gas.
Further, the metal layer is Ni, ti, W, al, ta, taC, tiN, tiW, niSi 2 ,CoSi 2 Any one or more of them.
In a second aspect, the invention provides an ohmic contact of a SiC power device, which is prepared by any one of the preparation methods.
Further, the SiC power device ohmic contact device can be applied to Schottky barrier diodes, metal oxide field effect transistors, MOS control thyristors, electron injection enhanced gate transistors, ultra-high power thyristors or insulated gate bipolar transistors.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides an ohmic contact of a SiC power device, a preparation method and application, which effectively simplify the manufacturing process of ohmic contact on the back of the power device, and the obtained contact resistivity can reach 10e -6 Ω·cm 2 The magnitude is high, so that the specific contact resistance and the power loss are effectively reduced;
according to the invention, the 3C-SiC material is formed on the back surface of the 4H-SiC substrate by adopting the mode of ion implantation, epitaxial growth or wafer bonding, a high-temperature annealing process is not needed, and ohmic contact can be formed by continuously depositing metal on the back surface of the pretreated silicon carbide substrate.
Drawings
Fig. 1 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to an embodiment of the present invention;
FIG. 2 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to a second embodiment of the present invention;
FIG. 3 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to a third embodiment of the present invention;
FIG. 4 is a schematic view of an ion implantation method according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an epitaxy method provided by an embodiment of the invention;
fig. 6 is a schematic diagram illustrating a wafer bonding method according to an embodiment of the invention.
Detailed Description
The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The ohmic contact and preparation method of the SiC power device provided by the invention are suitable for back ohmic contact of a SiC junction barrier Schottky diode and a SiC MOSFET and preparation of back ohmic contact of other devices similar to the SiC device, and the back ohmic contact comprises a metal oxide field effect transistor, an MOS control thyristor, an electron injection enhanced gate transistor, a super-power thyristor, an insulated gate bipolar transistor and the like.
The invention provides a flow chart of a preparation method of ohmic contact of a SiC power device, which mainly comprises the processes of processing, etching, removing water vapor and the like of the back of a 4H-SiC substrate, then preparing a material with a 3C-SiC crystal structure on the back of the 4H-SiC substrate, and finally depositing a metal layer on the back of the pretreated silicon carbide substrate to form ohmic contact.
Wherein the deposited metal layer is Ni, ti, W, al, ta, taC, tiN, tiW, niSi 2 ,CoSi 2 Any one or more of them.
The invention is further described below with reference to the accompanying drawings.
Example one
Fig. 1 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to this embodiment, which specifically includes the following steps:
step 1: performing hydrofluoric acid etching treatment on the back surface of the 4H-SiC substrate to remove oxide layer, organic matters and particle contamination on the back surface of the 4H-SiC substrate, and performing high-temperature N treatment 2 And removing water vapor on the back surface of the substrate in the atmosphere.
Step 2: the material with the 3C-SiC crystal structure is prepared by adopting an ion implantation method, and as shown in figure 4, the specific steps are as follows:
a. under the ion implantation condition of 0-100 ℃, the temperature is 5 multiplied by 10 18 ~5×10 20 cm -3 Injecting Al ions into the back surface of the 4H-SiC substrate;
b. preparing a carbon film with the thickness of 10nm to 30nm on the substrate 1 by adopting carbon film sputtering equipment;
c. performing high-temperature activation annealing process for 3-10min at 1700-1900 ℃ by using high-temperature activation annealing equipment to obtain a 3C-SiC crystal material;
d. the carbon film sputtered on the back surface is removed by oxygen plasma oxidation;
e. putting the back surface of the pretreated silicon carbide substrate into a high-temperature furnace for thermal oxidation of 500-800A, and then performing thermal oxidation on the back surface of the pretreated silicon carbide substrate in CI 2 The RIE etching system of Ar gas etches the oxide layer.
And step 3: depositing a Ni/Si metal layer, and sequentially depositing Ni and Si with the thicknesses of 10 to 50nm and 40 to 80nm as contact metal electrodes.
Example two
Fig. 2 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to this embodiment, which specifically includes the following steps:
step 1: and performing hydrofluoric acid etching treatment on the back of the 4H-SiC substrate, removing contamination of an oxide layer, organic matters and particles on the back of the substrate, and finally removing water vapor on the back of the substrate in a high-temperature N2 atmosphere.
Step 2: the method of growth epitaxy is adopted, as shown in fig. 5, and the specific steps are as follows:
a. any one or more of monosilane, propane and ethylene are selected as epitaxial precursors, and hydrogen or argon is selected as carrier gas. The flow rate of the carrier gas is 300-600sccm, the carrier gas and the epitaxial precursor are introduced 5 minutes ahead of the deposition, and a 4H-SiC substrate is selected;
b. depositing the pressure of 800Pa-1400Pa in a chemical vapor deposition system, depositing a 3C-SiC film on the back of a 4H-SiC substrate, wherein the deposition thickness is about 2-5 μm, and the growth temperature and growth speed of the 3C-SiC film are about 1500-1650 ℃ and 3-15 μm/H.
And step 3: and depositing a Ni/Si metal layer, and sequentially depositing Ni with the thickness of 10 to 50nm and Si with the thickness of 40 to 80nm as contact metal electrodes to form ohmic contact.
EXAMPLE III
Fig. 3 is a flowchart of a method for manufacturing an ohmic contact of a SiC power device according to this embodiment, which specifically includes the following steps:
step 1: etching the back of the 4H-SiC substrate with hydrofluoric acid to remove the contamination of oxide layer, organic matter and particles on the back of the substrate, and finally performing high-temperature N 2 And removing water vapor on the back surface of the substrate in the atmosphere.
And 2, step: the method of bonding wafers, as shown in fig. 6, includes the following steps:
a. connecting the 4H-SiC substrate with the surface of the 3C-SiC wafer to be bonded;
b. performing activation annealing at 1600-1900 ℃ for 10-60min in Ar atmosphere to obtain a bonded composite substrate;
c. putting the non-bonded surface of the 3C-SiC wafer into a high-temperature furnace for thermal oxidation 500-800A to obtain an oxidized composite substrate, and then performing thermal oxidation on the oxidized composite substrate at CI 2 And etching by using an RIE etching system of Ar gas.
And 3, step 3: and depositing a Ni/Si metal layer, and sequentially depositing Ni and Si with the thickness of 10 to 50nm and 40 to 80nm as a contact metal electrode.
The invention also provides an ohmic contact of the SiC power device, which is prepared by any one of the preparation methods.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, it is possible to make various improvements and modifications without departing from the technical principle of the present invention, and those improvements and modifications should be considered as the protection scope of the present invention.

Claims (9)

1. A preparation method of ohmic contact of a SiC power device is characterized by comprising the following steps:
preprocessing the back of the 4H-SiC substrate, including the processes of etching and removing water vapor;
preparing a material with a 3C-SiC crystal structure on the back of the pretreated 4H-SiC substrate;
and depositing a metal layer on the surface of the 3C-SiC crystal to prepare ohmic contact.
2. The method for preparing the ohmic contact of the SiC power device as claimed in claim 1, wherein the etching comprises treating the back surface of the silicon carbide substrate with hydrofluoric acid and/or hydrochloric acid and then removing moisture from the back surface of the substrate.
3. The preparation method of the ohmic contact of the SiC power device according to claim 1, wherein a material with a 3C-SiC crystal structure is prepared on the back surface of the pretreated 4H-SiC substrate, and the preparation method comprises the following steps:
at 0-100 deg.C, mixing 5 × 10 18 ~5×10 20 cm -3 Injecting Al ions into the back surface of the 4H-SiC substrate;
sputtering a carbon film with the thickness of 10nm to 30nm on the back surface of the 4H-SiC substrate by adopting carbon film sputtering equipment after the ions are injected;
performing activation annealing treatment on a 4H-SiC substrate with a carbon film sputtered on the back surface of the substrate at 1700-1900 ℃ for 3-10min to prepare a 3C-SiC crystal material;
oxidizing and removing the carbon film sputtered on the back of the 4H-SiC substrate;
putting the back surface of the 4H-SiC substrate with the carbon film removed into a high-temperature furnace for thermal oxidation of 500 to 800A, and then placing the substrate in CI 2 And etching by using an RIE etching system of Ar gas.
4. The preparation method of the ohmic contact of the SiC power device according to claim 1, wherein a material with a 3C-SiC crystal structure is prepared on the back surface of the pretreated 4H-SiC substrate, and the preparation method comprises the following steps:
selecting monosilane or propane or ethylene as an epitaxial precursor, and selecting hydrogen and/or argon as a carrier gas to be introduced in advance, wherein the flow rate of the carrier gas is 300-600sccm;
in the chemical vapor deposition system, the epitaxial precursor deposits a 3C-SiC crystal structure with a thickness of 2-5 μm on the back of the pretreated 4H-SiC substrate.
5. The preparation method of the ohmic contact of the SiC power device according to claim 4, wherein the deposition pressure in the chemical vapor deposition system is 800Pa-1400Pa, the growth temperature of the 3C-SiC crystal structure is 1500-1650 ℃, and the growth speed is 3-15 μm/h.
6. The method for preparing the ohmic contact of the SiC power device according to claim 1, wherein a material with a 3C-SiC crystal structure is prepared on the back of the pretreated 4H-SiC substrate, and the method comprises the following steps:
connecting the pretreated 4H-SiC substrate and the surface of the 3C-SiC wafer, which needs to be bonded;
performing activation annealing at 1600-1900 ℃ in Ar atmosphere, and bonding the contact surface;
the unbonded surface of the 3C-SiC wafer is put into a high-temperature furnace for thermal oxidation 500A-800A, and then the surface is subjected to CI 2 And etching by using an RIE etching system of Ar gas.
7. The method of claim 1, wherein the metal layer is Ni, ti, W, al, ta, taC, tiN, tiW, niSi 2 ,CoSi 2 Any one or more of them.
8. An ohmic contact of a SiC power device, characterized in that the ohmic contact of the SiC power device is prepared by the preparation method of any one of claims 1 to 7.
9. The SiC power device ohmic contact of claim 8, applied to Schottky barrier diodes, metal oxide field effect transistors, MOS controlled thyristors, electron injection enhanced gate transistors, ultra high power thyristors or insulated gate bipolar transistors.
CN202211376435.7A 2022-11-04 2022-11-04 SiC power device ohmic contact, preparation method and application Pending CN115565856A (en)

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Application Number Priority Date Filing Date Title
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