Transistor Gate Insulator Layout for Leakage and Voltage Resistance
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Solution Overview
Problem
The existing transistor structures with semiconductor films divided into small island regions are prone to localized protrusions and thin film portions in the gate insulating film, leading to decreased yield due to issues like voltage resistance deterioration and increased susceptibility to leakage.
Innovation Solution
A transistor design featuring a semiconductor portion with a gate insulating film that includes a layered structure with specific thick portions, allowing for improved distribution of film thickness and reduced likelihood of protrusions, thereby enhancing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the semiconductor film is divided into a plurality of small island regions, then grain boundary concentration is prevented and source-drain current uniformity is improved, but the sum of outer peripheral end lengths increases leading to localized protrusions and thin film portions
Solution Approach 1:
The gate insulating film is designed with non-uniform thickness, featuring first thick portions at specific locations and a second thick portion with greater thickness between them. This local variation in film thickness compensates for the increased outer peripheral end length, preventing localized protrusions and maintaining voltage resistance performance while allowing the semiconductor film to be divided into multiple small island regions for improved current uniformity.
2Manufacturing precision
If the semiconductor film is divided into a plurality of small island regions, then grain boundary distribution is improved, but the likelihood of minute foreign matter becoming protrusions increases
Solution Approach 1:
The gate insulating film incorporates second thick portions with greater thickness than the first thick portions, positioned between adjacent small island regions. These additional thick portions serve as a cushioning layer that prevents minute foreign matter from creating localized protrusions that would otherwise compromise device performance, while still allowing the semiconductor film to be segmented for improved grain boundary distribution.
3Speed
If the gate insulating film is made uniformly thin to reduce capacitance, then switching speed is improved, but voltage resistance performance deteriorates
Solution Approach 1:
The gate insulating film employs a non-uniform thickness design with first thick portions and second thick portions of greater thickness, allowing different regions to serve different functions. The thinner regions reduce capacitance for improved switching speed, while the locally thickened portions maintain voltage resistance performance, resolving the trade-off between speed and reliability.
Data Source
AI summary
A transistor includes a semiconductor portion extending in a first direction, a first electrode extending in a second direction intersecting the first direction and is disposed overlapping a portion of the semiconductor portion, a first insulating film that is interposed between the first electrode and the semiconductor portion, a second electrode that is connected to the semiconductor portion, and a third electrode that is connected to the semiconductor portion, in which the first insulating film includes a first thick portion and a second thick portion having a film thickness greater than that of the first thick portion, at least two of the first thick portions are disposed at intervals in the second direction at positions overlapping both the first electrode and the semiconductor portion, and the second thick portion is disposed to be interposed between the two first thick portions in the second direction at a position overlapping both the first electrode and the semiconductor portion.