Gate-Fin Field Effect Transistors for Surface Breakdown Control
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Solution Overview
Problem
Field effect transistors often suffer from surface breakdown voltage due to complex extended low doped drain (LDD) structures, which increase process complexity and cost.
Innovation Solution
A semiconductor structure with a shallow trench isolation structure and a field effect transistor featuring line trenches, a channel region, a gate dielectric contacting all surfaces of the trenches, a gate electrode with planar and fin portions, and source and drain regions laterally spaced by the channel region, along with a method of forming these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex extended low doped drain (LDD) structure is used, then surface breakdown characteristics are improved, but process complexity and cost increase
Solution Approach 1:
The patent extracts the essential function of the complex LDD structure (surface breakdown protection) and implements it through a simpler gate electrode fin structure that protrudes into the trench, eliminating the need for extended LDD regions while maintaining the breakdown voltage characteristics
Solution Approach 2:
Instead of using extended LDD structures to protect the surface, the patent inverts the approach by using a protruding gate electrode fin structure that actively enhances the electric field distribution to improve surface breakdown characteristics, achieving the same protective effect through an opposite structural configuration
2Reliability
If complex extended low doped drain (LDD) structure is used, then surface breakdown characteristics are improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the costly extended LDD structure while retaining the essential surface breakdown protection function through a simpler gate electrode fin design, reducing manufacturing steps and material usage
Solution Approach 2:
The patent replaces the expensive and complex extended LDD structure with a more economical gate electrode fin structure that achieves the same protective function, effectively using a simpler, cheaper alternative to accomplish the required reliability
Data Source
AI summary
A field effect transistor includes at least one line trench extending downward from a top surface of a channel region which laterally surrounds or underlies the at least one line trench, a gate dielectric contacting all surfaces of the at least one line trench and including a planar gate dielectric portion that extends over an entirety of a top surface of the channel region, a gate electrode, a source region, and a drain region.