Oxide Semiconductor Transistor Electrode Contact Structure
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Solution Overview
Problem
Current semiconductor devices using oxide semiconductors face challenges in achieving favorable electrical characteristics, high on-state current, miniaturization, low power consumption, high integration, and reliable data retention even when power is stopped.
Innovation Solution
A semiconductor device with a transistor structure that includes an oxide semiconductor layer, a source electrode layer, and a drain electrode layer, where the electrode layers have a specific conductive layer configuration to minimize oxygen depletion from the insulating layer, allowing for improved electrical characteristics and increased on-state current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transistor structure with oxide semiconductor is used, then the device can be manufactured with existing processes, but the electrical characteristics are not favorable and on-state current is low
Solution Approach 1:
The source electrode layer and drain electrode layer are divided into multiple conductive layers (first conductive layer and second conductive layer) instead of using a single uniform electrode structure. This segmentation allows the first conductive layer to contact the top surface of the oxide semiconductor layer while the second conductive layer contacts the side surface, enabling better electrical contact and higher on-state current without requiring entirely new manufacturing processes
Solution Approach 2:
The electrode structure transitions from a planar contact (only top surface) to a three-dimensional contact configuration that includes both top surface and side surface contact. This dimensional change increases the contact area between the electrode and oxide semiconductor layer, improving electrical characteristics and on-state current while remaining compatible with existing thin-film fabrication techniques
2Length of moving object
If the oxide semiconductor layer is made thinner to enable miniaturization, then the device size is reduced, but the on-state current decreases
Solution Approach 1:
By extending the electrode contact to include the side surface of the oxide semiconductor layer in addition to the top surface, the effective contact area is increased without increasing the planar footprint of the device. This allows thinner oxide semiconductor layers to maintain sufficient on-state current while enabling device miniaturization
Solution Approach 2:
The second conductive layer is positioned to contact the side surface of the oxide semiconductor layer, effectively nesting the contact structure within the vertical profile of the device. This nested configuration maximizes the use of available space, allowing improved electrical contact without increasing the device's planar dimensions
3Use of energy by moving object
If the oxide semiconductor layer is made thinner to reduce power consumption, then the power consumption is reduced, but the electrical characteristics deteriorate
Solution Approach 1:
The multi-layer electrode structure with separate top surface contact (first conductive layer) and side surface contact (second conductive layer) compensates for the reduced channel thickness by increasing the effective contact area, maintaining good electrical characteristics even when the oxide semiconductor layer is made thinner for lower power consumption
Data Source
AI summary
A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a source electrode layer and a drain electrode layer which are electrically connected to an oxide semiconductor layer, a gate insulating film over the oxide semiconductor layer; the source electrode layer, and the drain electrode layer; and a gate electrode layer that overlaps with the oxide semiconductor layer, the source electrode layer, and the drain electrode layer with the gate insulating film positioned therebetween. The source electrode layer and the drain electrode layer each include a first conductive layer and a second conductive layer. The first conductive layer is in contact with a top surface of the oxide semiconductor layer. The second conductive layer is in contact with a side surface of the oxide semiconductor layer. The first conductive layer and the second conductive layer are electrically connected to each other.