Superjunction Drift Region Layout With Trench Sidewall Doping
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Solution Overview
Problem
There is a need for a cost-efficient method to form the drift region of a superjunction transistor device, which involves alternating regions of different doping types in a semiconductor body, as existing methods are inefficient and costly.
Innovation Solution
The method involves forming trenches in a semiconductor layer, implanting dopant atoms of different types into the trench sidewalls, filling the trenches with semiconductor material, and diffusing the dopants through a thermal process to create alternating regions of specific widths, allowing for the formation of a superjunction transistor device with enhanced voltage blocking capability and reduced on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to form the drift region with alternating doped regions, then the superjunction transistor device can be produced, but the production cost is high and the process is inefficient
Solution Approach 1:
The drift region is segmented into multiple alternating doped regions (first doped regions and second doped regions) with different conductivity types. This segmentation allows for optimized electrical characteristics while using a simplified formation process through trench-based doping, reducing both cost and complexity compared to conventional approaches.
Solution Approach 2:
Different regions of the drift region are given different doping types and concentrations to optimize local electrical properties. The first doped regions and second doped regions have complementary doping types, creating localized p-n junctions that improve voltage blocking capability and reduce on-resistance in specific areas while maintaining overall device performance.
2Ease of manufacture
If the number of semiconductor layers is reduced to lower production costs, then manufacturing becomes more cost-effective, but the voltage blocking capability and on-resistance performance may be compromised
Solution Approach 1:
The invention optimizes the width ratio between trenches and mesa regions, with the first width being at least 1.05 times the second width. This parameter optimization allows for effective voltage blocking and controlled on-resistance with fewer semiconductor layers, reducing production costs while maintaining reliable electrical performance through carefully controlled doping parameters and geometric dimensions.
3Manufacturing precision
If the first width of trenches is made larger than the second width of mesa regions, then the doping regions can be better formed with optimized electrical characteristics, but the device structure becomes more complex
Solution Approach 1:
The trench structure uses asymmetric dimensions where the first width (trench width) is deliberately made larger than the second width (mesa region width), with a ratio of at least 1.05. This asymmetric design optimizes the doping region formation and electrical characteristics while maintaining a relatively simple fabrication process, avoiding excessive structural complexity.
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 approach enables the cost-effective production of superjunction transistors with improved voltage blocking capabilities and reduced on-resistance by optimizing the width and depth of trenches, reducing the number of semiconductor layers required and thus lowering production costs.
Implementation Method 1
diffusing the first type dopant atoms and second type dopant atoms in a thermal process so that the first type dopant atoms form the first regions and the second type dopant atoms form the second regions
Implementation Method 2
implanting first type dopant atoms and second type dopant atoms into each of opposing sidewalls of the plurality of trenches
Data Source
AI summary
A method for forming a drift region of a superjunction transistor and a superjunction transistor device are disclosed. The method includes forming first regions of a first doping type and second regions of a second type in a semiconductor body such that the first and second regions are arranged alternatingly in the body. The first and second regions are formed by: forming trenches in at least one semiconductor layer; implanting first type dopant atoms and second type dopant atoms into opposing sidewalls of the trenches; filling the trenches with a semiconductor material; and diffusing the dopant atoms in a thermal process so that the first type dopant atoms form the first regions and the second type dopant atoms form the second regions. Each trench has a first width, the trenches are separated by mesa regions each having a second width, and the first width is greater than the second width.