Split-Gate Trench MOSFET Layout With Source-Connected Field Plate
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Solution Overview
Problem
The existing semiconductor device manufacturing process is inefficient due to the need for separate external connections for the field plate and source electrodes, leading to increased manufacturing costs and potential functional issues if holes do not reach the gate electrodes completely, affecting the reliability of the MOSFET.
Innovation Solution
A semiconductor device design where the field plate electrode is connected to the source electrode through a contact portion within the trench, allowing the gate electrode to function even if one of the divided gate electrodes is not fully connected, by using a specific hole configuration and interlayer insulating film structure to ensure electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If separate external connection members are used for the field plate electrode and source electrode, then the breakdown voltage can be improved, but the layout efficiency decreases and manufacturing cost increases
Solution Approach 1:
The field plate electrode and source electrode are merged into a single source electrode structure. The source electrode is configured to extend into the trench and make contact with the field plate electrode at the bottom, eliminating the need for separate connection members while maintaining the electrical connection function and improving layout efficiency.
2Ease of manufacture
If the field plate electrode is exposed to the upper surface by forming a region throughout the trench, then connection below the source electrode is enabled, but the gate electrode is divided requiring individual connections
Solution Approach 1:
The gate electrode is segmented into multiple portions along the trench, with each portion independently connected to the gate wiring through separate contact holes. This segmentation allows flexible connection strategies where not all portions need to be connected, simplifying the manufacturing process while maintaining device functionality.
3Reliability
If holes are formed to connect gate wiring to gate electrodes, then electrical connectivity is achieved, but reliability decreases if holes do not reach the gate electrode completely
Solution Approach 1:
The gate electrode is designed with extended portions that protrude toward the upper surface before hole formation. This preliminary extension ensures that even if holes are not formed with perfect precision, the extended gate electrode portions will still make contact with the gate wiring, guaranteeing electrical connectivity and MOSFET functionality.
4Adaptability or versatility
If the gate electrode is divided into multiple portions, then flexibility in connection is improved, but the manufacturing process complexity increases
Solution Approach 1:
The gate electrode structure is designed with universal extended portions that can be selectively connected through standard contact hole formation processes. This multi-functional design allows the same structural feature to serve both as a connection point and as a precision tolerance buffer, simplifying the manufacturing process while maintaining connection flexibility.
Data Source
AI summary
An improved power MOSFET of a split gate structure including a gate electrode and a field plate electrode in a trench is disclosed. The improved power MOSFET includes a field plate electrode FP formed at a lower portion of a trench TR and a gate electrode GE formed an upper portion of the trench TR. The field plate electrode FP further includes a contact portion FPa which is formed at the upper portion of the trench TR to provide a source potential. The gate electrode GE further includes a connecting portion GEa at the both sides of the contact portion FPa in the trench TR. The connecting portion GEa electrically connects between one portion of the gate electrode GE at a region 2A side and the other portion of the gate electrode GE at a region 2A′ side.