Trench Charge Compensation in Semiconductor Devices
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Solution Overview
Problem
High voltage power switching devices face a trade-off between on-state resistance (Rdson) and breakdown voltage (BVdss), with existing superjunction devices presenting manufacturing challenges.
Innovation Solution
A semiconductor device with deep trench charge compensation structures, featuring multiple layers of opposite conductivity type separated by intrinsic layers, which balance charge and reduce intermixing, enhancing conduction efficiency and providing low Rdson and high BVdss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional superjunction devices use heavily-doped diffused n-type and p-type regions, then on-state resistance is reduced, but manufacturing complexity and difficulty increase significantly
Solution Approach 1:
The device segments the semiconductor body into multiple vertical columns, each containing alternating n-type and p-type superjunction regions. This segmentation allows independent formation of charge compensation regions in each column, simplifying the manufacturing process while maintaining the low on-state resistance through parallel current paths across multiple segments.
Solution Approach 2:
The patent transitions from planar superjunction structures to vertical columnar structures extending through the semiconductor body. This dimensional change enables charge compensation regions to be formed vertically between the n-type and p-type regions, providing a more efficient charge balance mechanism that reduces manufacturing difficulty while maintaining low on-state resistance.
2Reliability
If conventional superjunction devices use heavily-doped diffused n-type and p-type regions, then breakdown voltage is maintained, but manufacturing precision requirements become excessively stringent
Solution Approach 1:
The n-type and p-type superjunction regions are designed to automatically compensate for each other's charge through their inherent doping profiles and geometric arrangement. This self-compensation mechanism maintains the required breakdown voltage without requiring extremely precise control of doping concentrations and junction depths, thereby reducing manufacturing precision requirements.
Solution Approach 2:
The patent modifies the doping parameters and geometric dimensions of the superjunction regions to create a more tolerant design. By adjusting the doping concentrations, region thicknesses, and column spacing, the device achieves robust breakdown voltage characteristics that are less sensitive to manufacturing variations, thereby reducing the stringency of precision requirements.
3Reliability
If conventional superjunction devices use alternating n-type and p-type regions, then the trade-off between Rdson and BVdss is improved, but device structure complexity increases
Solution Approach 1:
The vertical columnar structure serves multiple functions simultaneously: it provides current conduction paths, establishes charge compensation regions, defines breakdown voltage characteristics, and enables scalable device design. This multi-functionality reduces the need for separate structural elements, thereby simplifying the overall device structure while maintaining the improved Rdson-BVdss trade-off.
Solution Approach 2:
The patent employs a nested structure where p-type regions are positioned within or adjacent to n-type regions in a compact vertical arrangement. This nesting efficiently utilizes the semiconductor body volume, provides intimate charge compensation interfaces, and simplifies the overall structural complexity by integrating multiple functional regions into a compact hierarchical arrangement.
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 solution effectively reduces on-state resistance and increases breakdown voltage, improving the performance of high voltage power switching devices while simplifying manufacturing processes.
Implementation Method 1
multiple monocrystalline semiconductor layers including alternately spaced, doped layers of opposite conductivity type separated by intrinsic or buffer layers to balance charge and reduce intermixing
Data Source
AI summary
In one embodiment, a method of forming a semiconductor device with trench charge compensation structures includes exposing the trench sidewalls to a reduced temperature hydrogen desorption process to enhance the formation of monocrystalline semiconductor layers.