Semiconductor Device Metal Electrode Oxidation Resistance
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Solution Overview
Problem
The existing power semiconductor devices face increased ohmic resistance and forward voltage due to oxidation of metal layers in contact with n-type and p-type regions, leading to higher contact resistance and inefficiency.
Innovation Solution
A semiconductor device with a metal electrode structure comprising a first metal layer in contact with both n-type and p-type regions, and a second metal layer with a lower oxygen concentration than the interface between the first metal layer and the regions, formed through methods such as sputtering or chemical treatment to minimize natural oxide film presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is used in contact with n-type and p-type regions to reduce forward voltage, then ohmic resistance is reduced, but the metal layer undergoes oxidation increasing contact resistance
Solution Approach 1:
The metal electrode is divided into multiple layers with distinct functions: the first metal layer (Al or Al-Si alloy) provides low ohmic resistance contact with semiconductor regions, while the second metal layer (Ni or Ni-Si alloy) serves as an oxidation-resistant protective layer. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The invention uses a composite multi-layer metal structure combining different metal materials with complementary properties. The aluminum-based first layer provides excellent electrical conductivity and low contact resistance, while the nickel-based second layer provides oxidation resistance, creating a composite electrode system that achieves both low resistance and high reliability.
2Reliability
If a multi-layer metal structure is formed to prevent oxidation, then device complexity increases, but contact resistance is reduced
Solution Approach 1:
The multi-layer structure applies local quality by providing different material properties at different locations within the electrode: the first layer contacts the semiconductor regions directly where low resistance is critical, while the second layer is positioned at the exposed surface where oxidation resistance is critical. Each layer's properties are optimized for its specific local function.
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
This configuration reduces ohmic resistance and forward voltage by maintaining low oxygen concentrations at the interfaces, enhancing the performance of semiconductor devices like diodes and RC-IGBTs.
Implementation Method 1
a first metal layer 6a in contact with both of the n cathode layer 4a and the p cathode layer 4b. The first metal layer 6a is in ohmic contact with the n cathode layer 4a and the p cathode layer 4b
Implementation Method 2
forming the first metal layer 6a and the second metal layer 6b through sputtering
Data Source
AI summary
A semiconductor device, which is a diode, includes the following: an n cathode layer, which is an n-type region, disposed in a surface layer of a semiconductor substrate; a p cathode layer, which is a p-type region, disposed in the surface layer; and a cathode electrode, which is a metal electrode, in contact with both of the n cathode layer and the p cathode layer. The cathode electrode includes a first metal layer in contact with both of the n cathode layer and the p cathode layer, and a second metal layer disposed on the first metal layer. A contact surface between the first metal layer and the second metal layer has an oxygen concentration lower than the oxygen concentration of a contact surface between the first metal layer, and the n cathode layer and the p cathode layer.