Auxiliary Trench Structures for Semiconductor Device Parameter Stability
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Solution Overview
Problem
The processing of trench semiconductor devices, such as power trench field effect transistors, faces challenges in maintaining consistent device parameters due to variations in trench distribution across the chip area, leading to differences in device behavior between edge and center regions.
Innovation Solution
The implementation of a semiconductor device with a trench transistor cell array and edge termination region, featuring auxiliary trench structures that are electrically connected and decoupled from the main trench electrodes, which helps stabilize device parameters by improving the reliability of trench semiconductor devices through precise etching and edge termination techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trenches are distributed over a chip area, then device functionality is achieved, but device parameters become unstable due to variations between edge and center regions
Solution Approach 1:
The patent segments the trench structure by introducing auxiliary trenches that are electrically decoupled from the main transistor trenches. These auxiliary trenches are distributed along the lateral direction and separated into different electrical groups, creating independent segments that can be individually controlled. This segmentation allows edge regions to be treated differently from center regions, compensating for distribution variations and stabilizing overall device parameters.
Solution Approach 2:
The patent applies local quality by giving different electrical characteristics to different spatial regions. The auxiliary trenches at edge locations have different electrical connections compared to center regions, with specific trenches electrically connected to different potential levels. This localized differentiation compensates for edge effects and ensures uniform device behavior across the chip area.
2Manufacturing precision
If chemical mechanical polishing is used to improve etching precision, then manufacturing precision improves, but process complexity increases
Solution Approach 1:
The patent employs preliminary action by performing chemical mechanical polishing on the electrode material before final trench formation. This preliminary planarization step ensures that subsequent etching processes achieve higher precision by working on a uniformly flat surface, reducing the need for multiple corrective processing steps and thereby managing overall process complexity.
3Reliability
If auxiliary trench structures are added to stabilize device parameters, then reliability improves, but device complexity increases
Solution Approach 1:
The auxiliary trench structures serve multiple functions simultaneously: they provide electrical decoupling to stabilize device parameters, act as field plates for edge termination, and enable independent electrical control of different chip regions. This multi-functionality allows a single structural addition to address multiple reliability issues without proportionally increasing complexity.
Solution Approach 2:
The patent creates equipotential regions by electrically connecting certain auxiliary trenches together and to specific potential levels. This equipotential arrangement stabilizes the electrical environment in edge regions, compensating for variations in trench distribution and reducing device parameter instability without requiring complex individual control of each trench.
Data Source
AI summary
An embodiment of a semiconductor device comprises a trench transistor cell array in a semiconductor body. The semiconductor device further comprises an edge termination region of the trench transistor cell array. At least two first auxiliary trench structures extend into the semiconductor body from a first side and are consecutively arranged along a lateral direction. The edge termination region is arranged, along the lateral direction, between the trench transistor cell array and the at least two first auxiliary trench structures. First auxiliary electrodes in the at least two first auxiliary trench structures are electrically connected together and electrically decoupled from electrodes in trenches of the trench transistor cell array.