Semiconductor Device Etching for Power Transistor Performance
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Solution Overview
Problem
Power transistors in automotive and industrial electronics face challenges in achieving low on-state resistance while maintaining high voltage blocking capability, particularly in thin semiconductor substrates where existing methods are inefficient in manufacturing and patterning.
Innovation Solution
A method involving the formation of a mask with inert structures on a semiconductor substrate, followed by epitaxial growth and anisotropic etching, which induces different etch rates based on the pattern of inert structures, allowing for the creation of a power semiconductor device with a stepped rear surface and controlled thickness, enabling efficient voltage blocking and current conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional manufacturing methods are used on thin substrates, then substrate thickness is reduced, but manufacturing efficiency and patterning quality deteriorate
Solution Approach 1:
The method performs preliminary thinning of the substrate before device fabrication, and uses preliminary patterning steps to create masks that define subsequent etching regions. This preliminary action enables efficient processing of thin substrates without compromising manufacturing productivity.
Solution Approach 2:
The patent replaces conventional mechanical patterning methods with chemical etching processes that use patterned masks. This substitution allows for higher precision and efficiency in creating device structures on thin substrates, resolving the contradiction between substrate thinness and manufacturing efficiency.
2Manufacturing precision
If conventional etching methods are used, then manufacturing process is simple, but etching precision and anisotropy are insufficient
Solution Approach 1:
The patent introduces patterned masks as intermediary structures that mediate between the etching chemistry and the desired final pattern. These masks enable precise control over etching locations and depths, achieving high etching precision while managing process complexity through systematic mask design and application.
Solution Approach 2:
The method applies different etching conditions and mask patterns to different regions of the substrate to achieve locally optimized etching precision. By varying mask patterns, etching times, and chemical compositions across different areas, the process achieves high precision without requiring uniformly complex procedures throughout.
3Reliability
If uniform thickness is maintained, then manufacturing is easier, but on-state resistance increases
Solution Approach 1:
The patent creates local variations in substrate thickness through selective etching processes. Different regions of the substrate are etched to different depths based on patterned masks, creating locally optimized thickness profiles that reduce on-state resistance in current-conducting regions while maintaining adequate thickness for voltage blocking in other regions.
Solution Approach 2:
The substrate is segmented into different thickness zones through selective etching. By dividing the substrate into regions with different thicknesses tailored to specific functional requirements, the method simultaneously achieves low on-state resistance in active regions and high voltage blocking capability in termination regions.
4Reliability
If rear surface is left flat, then processing is simpler, but voltage blocking performance is reduced
Solution Approach 1:
The method performs preliminary patterning of the rear surface using etching processes before final device assembly. By creating the stepped structure in advance, the patent enables improved voltage blocking performance without complicating subsequent processing steps, as the structured surface is already in place for subsequent operations.
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 effectively reduces on-state resistance and enhances voltage blocking capability by creating a semiconductor device with a patterned rear surface and controlled thickness, improving the performance and robustness of power transistors in thin substrates.
Implementation Method 1
thereafter, anisotropically etching a semiconductor region laterally adjoining the inert structures
Implementation Method 2
forming a semiconductor layer over the first main surface
Data Source
AI summary
According to embodiments, a method for manufacturing a semiconductor device includes forming a mask comprising a pattern of inert structures on a side of a first main surface of a semiconductor substrate. A semiconductor layer is formed over the first main surface, and the semiconductor substrate is thinned from a second main surface opposite to the first main surface. Thereafter, a semiconductor region laterally adjoining the inert structures is anisotropically etched.