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SiC surface ohmic contact optimization method

An optimization method, ohmic contact technology, applied in electrical components, semiconductor/solid-state device manufacturing, circuits, etc., can solve problems such as damaging device performance, deteriorating electrode metal adhesion, increasing process difficulty, etc., to reduce generation and pollution, and improve performance and process optimization

Inactive Publication Date: 2018-12-25
NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when Ni metal forms an ohmic contact with SiC, the reaction will generate a large amount of carbon impurity
The generated carbon impurities are continuously precipitated during the process, polluting the product wafer, eventually deteriorating the adhesion of the electrode metal and destroying the performance of the device
On the other hand, in order to form a high-quality SiC surface ohmic contact, the Ni metal electrode needs to be annealed at a temperature greater than 900 degrees, which increases the difficulty of the process and limits the optimization and improvement of the process.

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0039] Such as figure 1 As shown, the SiC surface ohmic contact optimization method, the specific steps are as follows:

[0040] (1) On the SiC substrate, the side where the ohmic contact electrode needs to be formed is heavily doped by ion implantation, and activated by high-temperature annealing to form a SiC layer with a higher doping concentration;

[0041] The activation step of implanting ions can be performed simultaneously with other activation process steps of SiC products.

[0042] (2) On the surface of the SiC heavily doped layer, a thin layer of metal is grown, and the metal type is Ti, or Ni, or a Ti / Ni multilayer metal layer;

[0043] Select the metal type and proportion according to the needs. The selection of metal Ti can reduce the temperature required to form ohmic contact, but the ohmic contact resistance is higher than that of Ni metal; the thickness of the thin layer of metal is proportional to the thickness of heavily doped SiC, ensuring that TiSi can be...

Embodiment 2

[0049] Such as figure 2 As shown, the SiC surface ohmic contact optimization method, the specific steps are as follows:

[0050] (1) On the SiC substrate, on the side where the ohmic contact electrode needs to be formed, epitaxially grow a polysilicon layer with a certain thickness;

[0051] The grown polysilicon layer may also be an amorphous silicon layer or a good-quality single crystal silicon layer; the growth method may be LPCVD growth or other growth methods.

[0052] (2) doping the epitaxially grown polysilicon layer, and forming a heavily doped polysilicon layer after activation;

[0053] (3) On the surface of the heavily doped polysilicon layer, grow a Ni metal layer proportional to the thickness of the polysilicon;

[0054] The thickness of the grown polysilicon layer is proportional to the Ni metal, ensuring that the polysilicon layer can fully react.

[0055] (4) low-temperature annealing for a certain period of time, so that the metal Ni reacts with the polys...

Embodiment 3

[0066] Such as image 3 As shown, the SiC surface ohmic contact optimization method, the specific steps are as follows:

[0067] (1) On the SiC substrate, the side where the ohmic contact electrode needs to be formed is heavily doped by ion implantation and activated by high-temperature annealing;

[0068] (2) Epitaxially grow a polysilicon layer with a certain thickness on the surface of the SiC heavily doped layer;

[0069] (3) doping the epitaxially grown polysilicon layer, and forming a heavily doped polysilicon layer after activation;

[0070] (4) On the surface of the heavily doped polysilicon layer, grow a Ni metal layer proportional to the thickness of the polysilicon, or grow a Ti / Ni metal layer;

[0071] (5) Low temperature annealing for a certain period of time, so that the metal Ni reacts with the polysilicon layer to form a NiSi alloy, and the remaining part of the alloy layer is heavily doped with SiC layer;

[0072] (6) Continue high-temperature annealing of ...

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Abstract

The invention discloses some optimized schemes for forming surface ohmic contact in the preparation process of SiC-based device. The invention comprises three sub-schemes. The first part mainly adoptsheavy doping and mainly adopts Ti metal system, so that the required annealing temperature can be reduced, and good surface ohmic contact of SiC can be obtained after low-temperature alloy. In the second part, a polycrystalline silicon layer is introduced between the surface of SiC and the electrode metal Ni, so that most of the alloying reaction takes place between Ni and polycrystalline silicon, which reduces the formation and contamination of elemental carbon. In the third part, the ohmic contact properties and process of SiC surface are optimized by integrating and optimizing both the first two parts of the process.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a method for optimizing ohmic contact on a SiC surface. Background technique [0002] SiC materials have large bandgap width, high breakdown electric field, high saturation drift velocity and high thermal conductivity. The superior properties of these materials make them ideal materials for making high-power, high-frequency, high-temperature-resistant, and radiation-resistant devices. Silicon carbide Schottky diodes have a series of advantages such as high breakdown voltage, high current density, and high operating frequency, so their development prospects are very broad. [0003] The cathode electrode of the silicon carbide diode is an ohmic contact electrode, and the quality of the ohmic contact will affect the electrical performance of the device, especially the turn-on voltage value and the forward working resistance value. The smaller the ohmic contact resista...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L21/04H01L29/45
CPCH01L21/0485H01L29/45
Inventor 陈允峰黄润华李士颜柏松栗锐汪玲
Owner NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD