Semiconductor Device Corner Low-Impurity Region for Breakdown Prevention
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Solution Overview
Problem
Conventional semiconductor devices face challenges in preventing breakdown due to local impact ionization during switching operations, which often require additional processes that increase production costs, such as implanting impurities or forming grooves to enhance resistance.
Innovation Solution
A semiconductor device design featuring a semiconductor substrate with a first region of one conductivity type and a second region of another conductivity type, including a low-impurity-concentration region in the corners of the second region to reduce impact ionization without increasing production costs, by forming a p low-concentration layer with a lower impurity concentration than the surrounding regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional impurity implantation or groove formation is performed to prevent breakdown, then breakdown prevention is improved, but production cost increases
Solution Approach 1:
The patent applies local quality by forming a low-impurity-concentration region specifically at the corner portions of the second region, rather than uniformly modifying the entire structure. This localized approach reduces impact ionization at the critical corner areas where breakdown is most likely to occur, while avoiding the need for additional impurity implantation or groove formation processes that would increase production cost.
Solution Approach 2:
The patent changes the impurity concentration parameter locally at the corner portions by forming a low-impurity-concentration region with impurity concentration lower than the surrounding second region. This parameter change reduces the electric field strength at corner portions, preventing impact ionization and breakdown without requiring additional manufacturing processes.
2Strength
If the electric field is strengthened to improve current blocking, then current blocking is improved, but impact ionization increases causing breakdown
Solution Approach 1:
The patent applies local quality by creating a low-impurity-concentration region specifically at the corner portions where impact ionization is most problematic. This localized modification reduces the electric field strength at these critical points, preventing impact ionization while maintaining strong current blocking capability in the bulk regions of the device.
Solution Approach 2:
The patent converts the harmful effect of strong electric fields causing impact ionization into a benefit by strategically creating low-impurity-concentration regions at corner portions. These regions act as electric field relief zones that prevent breakdown, allowing the device to maintain overall high electric field strength for current blocking while avoiding localized breakdown at corners.
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 design effectively suppresses local impact ionization and prevents breakdown in semiconductor devices, achieving this without the need for additional processes that would raise production costs, thereby maintaining cost-effectiveness.
Implementation Method 1
local impact ionization and may result in breakdown
Implementation Method 2
the electric field is further strengthened in the corners of the device-formed region
Data Source
AI summary
In one surface of a semiconductor substrate, an n− layer, a p base layer, a p well layer, another p well layer, a channel stopper layer, an emitter electrode, a guard ring electrode, and a channel stopper electrode for example are formed. In the other surface of the semiconductor substrate, an n+ buffer layer, a p+ collector layer, and a collector electrode are formed. In a curved corner of the p well layer, a p low-concentration layer having a lower impurity concentration than the impurity concentration of the p well layer is formed from the surface to a predetermined depth.