Oxide Semiconductor Column Structure for Threshold and Contact Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving optimal threshold voltage and contact resistance due to uniform film thickness and continuous contact surfaces in transistor structures.
Innovation Solution
The semiconductor device incorporates a non-continuous semiconductor layer configuration with a cavity between specific portions, allowing for a thinner channel film thickness and wider, circular contact surfaces, enhancing threshold voltage and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform film thickness is used in the semiconductor layer, then the manufacturing process is simple, but the threshold voltage cannot be optimized
Solution Approach 1:
The semiconductor layer is divided into multiple regions with different thicknesses: a first semiconductor layer with first thickness, a second semiconductor layer with second thickness, and a third semiconductor layer with third thickness. This segmentation allows each region to have optimized electrical characteristics, achieving desired threshold voltage while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
Different portions of the semiconductor layer are given different thicknesses to achieve local optimization of electrical properties. The first, second, and third semiconductor layers have distinct thicknesses tailored to specific functional requirements, enabling precise control of threshold voltage and contact resistance in different device regions.
2Manufacturing precision
If a continuous contact surface is used between the semiconductor layer and electrode, then the structure is simple, but contact resistance is high
Solution Approach 1:
The contact interface between the semiconductor layer and electrode is segmented into multiple discrete contact regions rather than a continuous surface. This segmentation creates optimized contact pathways that reduce resistance while maintaining structural simplicity through straightforward electrode positioning on specific semiconductor layer portions.
3Manufacturing precision
If the channel film thickness is increased, then the transistor gain is improved, but the threshold voltage control becomes difficult
Solution Approach 1:
The channel region is divided into multiple semiconductor layers with different thicknesses. This segmentation enables the channel to have sufficient overall thickness for adequate gain while specific thinner regions provide precise threshold voltage control, resolving the trade-off between gain and threshold voltage controllability.
Solution Approach 2:
Different sections of the channel have locally optimized thicknesses. The first, second, and third semiconductor layers provide local thickness variations that simultaneously achieve high transistor gain in certain regions and precise threshold voltage control in other regions, eliminating the need to compromise between these competing requirements.
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first conductive layer between first and second insulating layers with an oxide semiconductor column extending in the first direction through these layers. A third insulating layer covers the column. The column has a first semiconductor portion at a first position matching the first insulating layer, a second semiconductor portion at a second position matching second insulating layer, and a third semiconductor portion at a third position matching the first conductive layer. The first semiconductor portion is continuous along a second direction between the third insulating layer, the second semiconductor portion is continuous along the second direction between the third insulating layer, but the third semiconductor portion is not continuous between the third insulating layer.