Semiconductor Buffer Layer Design for Leakage Current Control
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Solution Overview
Problem
Existing semiconductor device manufacturing techniques fail to adequately suppress the generation of non-implanted regions due to foreign matters on the implantation surface, leading to inadequate suppression of adverse effects on breakdown voltage and leakage current characteristics.
Innovation Solution
A semiconductor device structure with a first buffer layer and a second buffer layer, each having a higher impurity concentration peak than the drift layer, where the second buffer layer is formed closer to the surface and has a lower kurtosis of impurity concentration, and the impurities are implanted at different angles to minimize the impact of foreign matters, ensuring effective impurity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple impurity implantation steps are performed to form buffer layers, then breakdown voltage characteristics and leakage current characteristics are improved, but foreign matters on the implantation surface cause non-implanted regions that reduce manufacturing precision
Solution Approach 1:
The buffer layer formation is divided into multiple separate implantation steps, each creating a distinct buffer layer with specific impurity concentration. This segmentation allows each layer to be optimized independently while collectively suppressing adverse effects on breakdown voltage and leakage current characteristics.
Solution Approach 2:
The patent introduces angular diversity by implanting impurities at different angles (e.g., 0° and 45°) relative to the implantation surface normal. This dimensional change in implantation approach ensures that foreign matters on the surface cannot consistently block all implantation paths, thereby preventing non-implanted regions and improving manufacturing precision.
2Device complexity
If a single buffer layer is formed, then the structure is simple, but foreign matters on the implantation surface create non-implanted regions that adversely affect breakdown voltage and leakage current
Solution Approach 1:
Instead of forming a single buffer layer, the patent segments the buffer region into multiple layers with different impurity concentrations and depths. This segmentation ensures that even if foreign matters block some implantation, the multiple layers provide redundant coverage that maintains reliability of breakdown voltage and leakage current characteristics.
Solution Approach 2:
The patent adds angular dimension to the implantation process by using multiple implantation angles. This creates overlapping impurity distribution patterns that compensate for blocking effects of foreign matters, thereby maintaining reliability without significantly increasing structural complexity.
3Quantity of substance
If impurities are implanted at high dose to ensure sufficient buffer layer formation, then buffer layer effectiveness is improved, but foreign matters cause complete blocking leading to non-implanted regions
Solution Approach 1:
The total impurity dose is segmented across multiple implantation steps rather than delivered in a single high-dose step. Each step uses moderate dosing that is sufficient when combined with other steps, preventing complete blocking by foreign matters while ensuring adequate total impurity concentration in the buffer layer.
Solution Approach 2:
The patent uses multiple implantation angles to deliver impurities from different directions. This ensures that even at high total doses, foreign matters cannot completely block all implantation paths, thereby maintaining both sufficient impurity concentration and complete coverage.
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 proposed solution effectively suppresses the generation of non-implanted regions, stabilizing breakdown voltage and leakage current characteristics by ensuring proper impurity distribution and reducing the likelihood of non-implanted regions extending through the buffer layers.
Implementation Method 1
a first buffer layer of a first conductivity type is formed between the drift layer and the back surface impurity layer... and a second buffer layer are formed between the drift layer and the back surface impurity layer
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having a drift layer of a first conductivity type and a collector layer of a second conductivity type. A first buffer layer having a higher impurity concentration peak than that of the drift layer is formed between the drift layer and the collector layer and a second buffer layer having a higher impurity concentration peak than that of the drift layer is formed between the first buffer layer and the collector layer. A kurtosis of a peak of an impurity concentration of the second buffer layer is lower than a kurtosis of a peak of an impurity concentration of the first buffer layer.