Insulated-Gate Transistor Isolation Trench Simultaneous Etching
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Solution Overview
Problem
Existing insulated-gate transistors face challenges in isolating a sense region from an active region without significantly increasing the number of process steps, particularly in forming element isolation layers using insulators like oxides in silicon carbide substrates.
Innovation Solution
The design incorporates an isolation trench that surrounds the sense region, using insulating films and conductors made of the same material as the gate trench, allowing for simultaneous formation of the isolation trench and gate trench, thus isolating the sense region from the active region without increasing the process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an element isolation layer is formed between the main cell region and the sense cell region using insulators like oxides, then the sense region is isolated from the active region, but the number of process steps significantly increases
Solution Approach 1:
The patent merges the formation of the gate trench and isolation trench into a single simultaneous etching process. Both trenches are formed through the same etching step using a single etch mask, eliminating the need for separate etching processes. This integration maintains effective isolation between regions while significantly reducing the total number of manufacturing steps
Solution Approach 2:
The single etch mask serves multiple functions: it defines both the gate trench pattern and the isolation trench pattern simultaneously. This multi-functional approach allows one mask layer to control two critical structural features, reducing mask fabrication steps and simplifying the overall process flow while maintaining precise isolation
2Manufacturing precision
If separate etching processes are used for gate trench and isolation trench, then precise control is achieved, but the manufacturing complexity increases
Solution Approach 1:
The patent combines the etching of gate trenches and isolation trenches into a single etching process step. Both types of trenches are formed simultaneously through the same etching reaction conditions, temperature, and time parameters, achieving consistent precision for both structures while halving the number of etching steps required
Solution Approach 2:
A specifically designed etch mask acts as an intermediary that patterns both gate and isolation trenches simultaneously. The mask's geometric design and material properties enable it to define both trench types through a single etching exposure, translating complex dual-pattern requirements into a single fabrication step while maintaining precise dimensional control
Data Source
AI summary
The sense region is spaced from the active region. The isolation trench surrounds the sense region and isolates the sense region from the active region. The active region is provided with a first gate trench defined by a first side surface and a first bottom surface continuing to the first side surface. The first insulating film is in contact with both the first side surface and the first bottom surface. The first conductor is provided on the first insulating film. The second insulating film is provided in the isolation trench. The second conductor is provided on the second insulating film. The isolation trench reaches a first impurity region. The first insulating film is made of a material identical to that of the second insulating film. The first conductor is made of a material identical to that of the second conductor and is electrically isolated from the second conductor.