Oxide Semiconductor Channel Structure for Stable Normally-Off Operation
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Solution Overview
Problem
Existing semiconductor devices with oxide semiconductor transistors tend to have normally-on characteristics due to impurities such as water or hydrogen in the channel formation region, leading to instability in electrical characteristics.
Innovation Solution
A semiconductor device structure is developed with a semiconductor layer having a channel formation region and low-resistance source and drain regions, where the channel formation region is isolated from the low-resistance regions by a sidewall insulating layer, and the device includes a nitrogen-containing insulating layer to reduce impurity concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat treatment is performed in an oxygen atmosphere to reduce source and drain resistance, then the resistance of source and drain regions is reduced, but the channel formation region becomes contaminated with oxygen and water, causing normally-on characteristics
Solution Approach 1:
The patent divides the insulating layer into multiple segments: a first insulating layer covering the source and drain regions, and a second insulating layer covering the channel formation region. This segmentation allows different regions to be treated differently during heat treatment, enabling oxygen supply to source/drain regions while protecting the channel formation region from contamination.
Solution Approach 2:
The patent applies different properties to different parts of the insulating structure. The first insulating layer has oxygen permeability to supply oxygen to source and drain regions, while the second insulating layer has low oxygen permeability to protect the channel formation region. This local differentiation of properties resolves the contradiction between reducing source/drain resistance and preventing channel contamination.
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
The proposed solution achieves stable and favorable electrical characteristics by reducing the resistance of the source and drain regions and purifying the channel formation region, enabling miniaturization, high integration, and high productivity of semiconductor devices.
Implementation Method 1
the device includes a nitrogen-containing insulating layer to reduce impurity concentration
Data Source
AI summary
A semiconductor device that can be highly integrated is provided.The semiconductor device includes a semiconductor layer, a first insulating layer, a second insulating layer, a third insulating layer, and a first conductive layer. The third insulating layer is positioned over the semiconductor layer and includes a first opening over the semiconductor layer. The first conductive layer is positioned over the semiconductor layer, the first insulating layer is positioned between the first conductive layer and the semiconductor layer, and the second insulating layer is provided in a position that is in contact with a side surface of the first opening, the semiconductor layer, and the first insulating layer. The semiconductor layer includes a first portion overlapping with the first insulating layer, a pair of second portions between which the first portion is sandwiched and which overlap with the second insulating layer, and a pair of third portions between which the first portion and the pair of second portions are sandwiched and which overlap with neither the first insulating layer nor the second insulating layer. The first portion has a smaller width than the first opening and has a thinner shape of the semiconductor layer than the second portions, and the second portions have a thinner shape of the semiconductor layer than the third portions.