Oxygen-Doped N-Buffer Layer for Oscillation Suppression in Semiconductor Diodes
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Solution Overview
Problem
Existing semiconductor diodes face challenges in suppressing oscillation phenomena during high-frequency switching in power converters, leading to increased recovery loss, while current solutions either require high-cost proton irradiation, lengthy high-temperature processing, or compromise on withstand voltage and cosmic radiation ruggedness.
Innovation Solution
A method for manufacturing semiconductor diodes with an n-buffer layer using oxygen as a dopant, which diffuses deeply and forms a carrier concentration gradient, reducing oscillation by heat treatment in an oxygen atmosphere, thereby enhancing productivity and maintaining high withstand voltage and radiation resistance without line contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep n-buffer layer is formed using phosphorus diffusion at high temperature for long time, then oscillation phenomenon is suppressed, but productivity decreases and manufacturing cost increases
Solution Approach 1:
The patent changes the dopant material from phosphorus to oxygen, and adjusts the diffusion temperature from high temperature (1300°C) to moderate temperature (800-900°C). This parameter change enables the formation of an n-buffer layer with sufficient carrier concentration (1×10^16 to 1×10^18 atoms/cm³) without requiring lengthy high-temperature processing, thus improving productivity while maintaining oscillation suppression capability
Solution Approach 2:
The patent uses oxygen, which is abundant and inexpensive, as the dopant material instead of phosphorus. The oxygen diffusion process can be integrated into existing thermal processing steps, eliminating the need for separate, costly high-temperature diffusion equipment and processes
2Reliability
If proton irradiation is used to generate n-buffer layer, then oscillation phenomenon is suppressed, but manufacturing cost increases due to cyclotron requirement
Solution Approach 1:
The patent replaces the mechanical/proton irradiation method with a thermal diffusion process. Instead of using a cyclotron to accelerate protons into the semiconductor substrate, the patent uses thermal energy to drive oxygen diffusion, which can be performed in standard semiconductor furnaces without requiring expensive particle acceleration equipment
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 method effectively suppresses oscillation phenomena, improves productivity, reduces costs, and maintains excellent withstand voltage and cosmic radiation ruggedness, ensuring stable power conversion systems with reduced electromagnetic interference.
Implementation Method 1
a first diffusion step in which oxygen is diffused into a silicon semiconductor substrate
Implementation Method 2
The annealing step transforms the oxygen present in the substrate into thermal donors and increases the doping concentration
Implementation Method 3
forming a high n-doped cathode region in the substrate at one surface thereof, grinding the opposite surface of the substrate
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
An anode electrode and a cathode electrode formed on a silicon semiconductor substrate, p-type layer formed next to the anode electrode, an n-type layer formed next to the cathode electrode by a V-group element being diffused, an n- layer formed between the p-type layer and the n-type layer, and an n-buffer layer formed between the n- layer and the n-type layer and containing oxygen are provided and an oxygen concentration in an area of a width of at least 30 µm from a surface on a side of the n-type layer of the cathode electrode toward the anode electrode is set to 1 x 1017 cm-3 or more and also the oxygen concentration of the n- layer in a position in contact with the p-type layer is set to less than 3 x 1017 cm-3.