Trench MOSFET Gate Capacitance Reduction via Conductive Structures
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Solution Overview
Problem
In optimizing MOSFET performance, existing device structures and fabrication processes often face trade-offs where improvements in one parameter, such as figure of merit (on-resistance times total gate charge), result in degradation of other parameters like die size, limiting flexibility and efficiency.
Innovation Solution
The implementation of electronic devices with trenches containing fewer gate electrodes replaced by conductive structures, which reduces gate capacitance and allows for a smaller die size, improved performance, and increased flexibility in device packaging, while simplifying process integration by enabling top-side contact to conductive structures within the trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate electrodes are reduced and replaced by conductive structures, then gate capacitance is reduced and figure of merit is improved, but device complexity increases due to the need for insulating members and modified trench structures
Solution Approach 1:
The patent removes gate electrodes from alternating trenches and replaces them with simple conductive structures, extracting the gate function from those specific trenches while maintaining the necessary electrical control through the remaining gate electrodes in adjacent trenches. This reduction in gate electrode count directly lowers gate capacitance and improves figure of merit while reducing overall device complexity.
Solution Approach 2:
The patent segments the gate electrode arrangement by creating alternating patterns where some trenches contain gate electrodes while adjacent trenches contain only conductive structures. This segmentation allows the device to achieve lower gate capacitance through selective placement, improving figure of merit while managing complexity through a systematic alternating pattern rather than requiring complex individual structures in each trench.
2Area of stationary object
If trenches contain fewer gate electrodes, then gate capacitance and die size are reduced, but manufacturing precision requirements increase for forming insulating members and conductive structures
Solution Approach 1:
The patent divides trenches into alternating segments with gate electrodes and segments with conductive structures only. This segmentation creates a regular repeating pattern that simplifies manufacturing by using standard alternating deposition and etching processes, reducing the precision requirements compared to forming complex individual structures in each trench while still achieving reduced die size.
Solution Approach 2:
The patent uses universal deposition and patterning processes that can form both gate electrodes and conductive structures in the same alternating trench pattern. This multi-functional approach allows a single set of manufacturing processes to create the differentiated trench structures, reducing precision requirements compared to requiring separate specialized processes for each trench type.
3Productivity
If gate electrodes are removed from alternating trenches, then device performance is improved with smaller die size, but process integration complexity increases
Solution Approach 1:
The patent segments the trench array into alternating regions with full gate electrode structures and regions with conductive structures only. This segmentation enables improved device performance through reduced gate capacitance while maintaining relatively simple process integration by using sequential deposition steps that naturally create the alternating pattern through masking and etching processes.
Solution Approach 2:
The patent performs preliminary patterning to define which trenches will contain gate electrodes versus conductive structures before final material deposition. This preliminary action establishes the alternating pattern early in the process, allowing subsequent steps to follow a standardized sequence that improves device performance while keeping process integration manageable through pre-planned material placement.
Data Source
AI summary
An electronic device can include a transistor structure, including a patterned semiconductor layer overlying a substrate and having a primary surface. The electronic device can further include first conductive structures within each of a first trench and a second trench, a gate electrode within the first trench and electrically insulated from the first conductive structure, a first insulating member disposed between the gate electrode and the first conductive structure within the first trench, and a second conductive structure within the second trench. The second conductive structure can be electrically connected to the first conductive structures and is electrically insulated from the gate electrode. The electronic device can further include a second insulating member disposed between the second conductive structure and the first conductive structure within the second trench. Processing sequences can be used that simplify formation of the features within the electronic device.