FinFET Support Structure for Stable Gate Trench Etching
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Solution Overview
Problem
Trench MOSFETs and FinFETs face mechanical instability due to the free-standing nature of narrow fins before gate electrode introduction, which can lead to structural issues during the etching process.
Innovation Solution
A support structure is provided using a mask that represents the fins, extending from the source layer to the drain layer, with supports connecting adjacent fins to stabilize them, allowing for continuous gate trenches and reduced mechanical instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If narrow fins are used to increase device density, then the number of gate electrodes that can be arranged increases, but the mechanical stability of the fins deteriorates
Solution Approach 1:
A support structure is introduced as an intermediary element between adjacent fins to provide mechanical stability. The support structure connects the fins laterally without interfering with the vertical gate trench etching process, allowing narrow fins to maintain both high density and structural integrity during manufacturing.
Solution Approach 2:
The support structure is segmented to connect only adjacent fins while leaving other regions open for gate trench formation. This selective segmentation allows the fins to be stabilized where needed while maintaining the necessary spaces for gate electrode introduction.
2Stability of the object's composition
If support structure is introduced to stabilize fins, then mechanical stability improves, but device complexity increases
Solution Approach 1:
The support structure serves multiple functions: it provides mechanical stability to narrow fins, maintains spacing between adjacent fins, and allows continuous gate trenches to be formed. By combining these functions into a single structural element, the overall device complexity is minimized while achieving the desired stability.
3Reliability
If continuous gate trenches are formed, then gate electrode continuity is improved, but the risk of disrupting fin structure increases
Solution Approach 1:
The support structure is formed in advance before the gate trench etching process. This preliminary action ensures that the fins are already stabilized and protected when the continuous gate trenches are subsequently formed, eliminating the risk of structural disruption during the etching process.
Data Source
AI summary
A field-effect transistor. The field-effect transistor includes: a source layer doped according to a first type, a drain layer doped according to a first type, a channel layer located vertically between the source layer doped according to a first type and the drain layer doped according to a first type, and, extending in particular horizontally, fins and gate trenches, wherein the fins and the gate trenches in each case extend in the vertical direction from the source layer doped according to a first type to the drain layer doped according to a first type, and wherein the gate trenches are in each case formed between two adjacent fins, wherein the field-effect transistor further includes a support structure for the fins.