Oxide Semiconductor Transistor Layout for Hot-Carrier Stability
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Solution Overview
Problem
Semiconductor devices using oxide transistors experience significant threshold voltage shifts due to degradation caused by hot carriers resulting from high voltage application between the source and drain.
Innovation Solution
The semiconductor device incorporates a second insulating film with a thick film region and a thin film region, where the thick film region suppresses hydrogen diffusion and the thin film region allows hydrogen to reach the oxide semiconductor, forming low-resistance regions adjacent to the channel region, thereby reducing degradation and maintaining high resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high voltage is applied between the source and drain to improve transistor performance, then the transistor can operate with higher drive current, but degradation by hot carriers occurs causing significant threshold voltage shift
Solution Approach 1:
The second insulating film is designed with different thicknesses in different regions: a first thickness in the channel region and a second thickness (greater than the first) in the low-resistance region. This local variation in film thickness creates different hydrogen diffusion characteristics in different regions, allowing the low-resistance region to receive hydrogen while the channel region maintains higher resistance, thus suppressing hot carrier degradation without sacrificing drive current capability
Solution Approach 2:
The second insulating film acts as a hydrogen diffusion barrier with controlled permeability. By adjusting its thickness in different regions, it mediates the hydrogen diffusion process to selectively supply hydrogen to the low-resistance region while preventing excessive hydrogen from reaching the channel region, thereby resolving the contradiction between maintaining low resistance and suppressing degradation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses degradation from hot carriers, stabilizes the threshold voltage, and enhances the reliability of the oxide semiconductor transistor.
Implementation Method 1
the thick film region suppresses hydrogen diffusion
Implementation Method 2
the thin film region allows hydrogen to reach the oxide semiconductor
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first insulating film formed of silicon nitride, a second insulating film disposed above the first insulating film and formed of silicon oxide, including a first region and a peripheral region surrounding the first region and thinner than the first region, an oxide semiconductor disposed on the second insulating film and intersecting the first region, a source electrode overlapping the peripheral region and a drain electrode overlapping the peripheral region. The first region is located between the source electrode and the drain electrode and separated from the source electrode and the drain electrode.