SiC Electrode Layer Composition for Conductivity and Adhesion
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Solution Overview
Problem
Existing methods for forming an electrode layer on a silicon carbide substrate face challenges in enhancing electrical conductivity while suppressing the precipitation of C atoms on the surface, leading to impaired conductivity and potential peeling of metal pad layers.
Innovation Solution
A semiconductor device with an electrode layer containing Ni atoms not less than 67% of the total Ni and Si atoms, where the surface side has a lower C atom concentration, and a method involving laser annealing to form a nickel silicide compound at the substrate interface, along with a metal pad layer like Al, to enhance conductivity and prevent C diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ratio of Ni atoms is increased to enhance electrical conductivity of the electrode layer, then electrical conductivity is improved, but C atoms are precipitated from the silicon carbide substrate to the surface of the electrode layer during annealing
Solution Approach 1:
The patent changes the compositional parameters by setting Ni atom ratio to at least 67% and controlling C atom concentration on the surface side to be lower than Ni atom concentration. This parameter optimization resolves the contradiction by achieving high conductivity while suppressing C precipitation through precise compositional control
Solution Approach 2:
The electrode layer is designed as a composite structure containing Ni atoms, Si atoms, and controlled C atom distribution. The composite nature with specific atomic ratios and the presence of Ni-Si compounds at the substrate interface enable simultaneous achievement of high conductivity and suppressed C precipitation
2Reliability
If the ratio of Ni atoms is increased to enhance electrical conductivity, then electrical conductivity is improved, but adhesion of metal pad layer to electrode layer deteriorates
Solution Approach 1:
By controlling C atom concentration on the surface side to be lower than Ni atom concentration and maintaining Ni atom ratio at least 67%, the patent optimizes surface composition parameters to improve both conductivity and adhesion properties simultaneously
Solution Approach 2:
The electrode layer exhibits local quality differentiation with Ni-Si compounds concentrated at the substrate interface region and controlled C atom distribution at the surface side. This spatial variation in composition allows the interface region to provide strong adhesion while the surface region provides high conductivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach effectively enhances electrical conductivity of the electrode layer and reduces C atom precipitation on the surface, minimizing the likelihood of metal pad layer peeling and improving overall device performance.
Implementation Method 1
By annealing the material layer with laser beams, an electrode layer of which side at least in contact with the silicon carbide substrate contains a compound of Si and Ni is formed
Data Source
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AI summary
An electrode layer (16) lies on a silicon carbide substrate (90) in contact therewith and has Ni atoms and Si atoms. The number of Ni atoms is not less than 67% of the total number ofNi atoms and Si atoms. A side of the electrode layer (16) at least in contact with the silicon carbide substrate (90) contains a compound of Si and Ni. On a surface side of the electrode layer (16), C atom concentration is lower than Ni atom concentration. Thus, improvement in electrical conductivity of the electrode layer (16) and suppression of precipitation of C atoms at the surface of the electrode layer (16) can both be achieved.