Semiconductor Device Asymmetric Anode Cathode Diffusion Depth
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Solution Overview
Problem
The VF-EREC trade-off characteristics of semiconductor diodes are highly dependent on irradiation angle, temperature, and lattice defects, leading to fluctuations in electrical characteristics and thermal runaway due to self-heating and leak currents.
Innovation Solution
A semiconductor device design featuring a drift layer with specific p-type and n-type anode and cathode layers, where the first p-type anode layer has a greater diffusion depth and impurity concentration than the second, and the n-type cathode layer has a greater diffusion depth and impurity concentration than the p-type, allowing for adjustable VF-EREC characteristics without lifetime control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lifetime control using electron/ion beam irradiation is used to adjust VF-EREC trade-off characteristics, then the VF-EREC trade-off characteristics can be controlled, but the characteristics vary largely depending on irradiation angle, temperature, and lattice defects
Solution Approach 1:
The patent changes the physical and chemical parameters of the semiconductor layers by controlling diffusion depth and impurity concentration during manufacturing. The first p-type anode layer has greater diffusion depth and impurity concentration than the second, while the n-type cathode layer has greater diffusion depth and impurity concentration than the p-type cathode layer. This parameter-based approach during fabrication eliminates the need for post-manufacturing lifetime control and ensures stable electrical characteristics independent of operating conditions.
2Adaptability or versatility
If lifetime control is used to adjust VF-EREC trade-off characteristics, then characteristic adjustment is possible, but thermal runaway occurs during high-temperature operation due to large leak current
Solution Approach 1:
The patent applies local quality by creating regions with different impurity concentrations and diffusion depths within the semiconductor structure. The first p-type anode layer has higher impurity concentration and greater diffusion depth compared to the second p-type anode layer, while the n-type cathode layer has higher impurity concentration and greater diffusion depth than the p-type cathode layer. This localized variation in material properties optimizes carrier distribution and reduces leak current in specific regions, preventing thermal runaway during high-temperature operation.
3Adaptability or versatility
If conventional lifetime control methods are used, then VF-EREC characteristics can be modified, but snap-off and oscillation occur
Solution Approach 1:
The patent implements preliminary action by establishing the optimal impurity concentration and diffusion depth profiles during the manufacturing process itself. The first p-type anode layer is formed with greater diffusion depth and impurity concentration than the second, and the n-type cathode layer is formed with greater diffusion depth and impurity concentration than the p-type cathode layer. This pre-established structural configuration prevents snap-off and oscillation during operation by ensuring proper carrier distribution before the device is put into service, eliminating the need for post-manufacturing lifetime control that causes instability.
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 design enables adjustable VF-EREC trade-off characteristics over a wide range, preventing snap-off and oscillation, improving cutoff performance and current density control, while avoiding the limitations of conventional lifetime control methods.
Implementation Method 1
the first p-type anode layer has a greater diffusion depth than a diffusion depth of the second p-type anode layer, the first p-type anode layer has a greater impurity concentration than an impurity concentration of the second p-type anode layer
Data Source
AI summary
First and second p-type anode layers (2,3) are provided side by side on a drift layer (1). N-type cathode layer (5) and p-type cathode layer (6) are provided side by side below the drift layer (1). An n-type buffer layer (7) is provided between the drift layer (1) and the n-type cathode layer (5) and between the drift layer (1) and the p-type cathode layer (6). The first p-type anode layer (2,2a,2b) has a greater diffusion depth than a diffusion depth of the second p-type anode layer (3). The first p-type anode layer (2,2a,2b) has a greater impurity concentration than an impurity concentration of the second p-type anode layer (3). The n-type cathode layer (5) has a greater diffusion depth than a diffusion depth of the p-type cathode layer (6). The n-type cathode layer (5) has a greater impurity concentration than an impurity concentration of the p-type cathode layer (6).