Semiconductor Device Embedded Conductive Layers Contact Resistance
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Solution Overview
Problem
The challenge in semiconductor devices is to achieve high-speed driving with improved on-state characteristics while minimizing the risk of short circuits between electrodes, particularly when using oxide semiconductors, where the thin gate insulating layer coverage failure leads to increased resistance and reliability issues.
Innovation Solution
The solution involves embedding conductive layers in an insulating layer, ensuring that the source and drain electrodes overlap with the gate electrode, and providing a large contact area between embedded conductive layers and electrodes, reducing contact resistance and enhancing channel formation region coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gate insulating layer is thinned for miniaturization, then the transistor size is reduced and integration density is improved, but coverage failure occurs leading to short circuits between electrodes
Solution Approach 1:
The gate electrode structure is segmented into multiple parts: a gate electrode main body and protruding portions that extend toward the source and drain electrodes. This segmentation allows the gate electrode to maintain proper spacing from the source/drain electrodes while ensuring complete coverage by the gate insulating layer, thereby preventing short circuits even when the gate insulating layer is thinned for miniaturization.
Solution Approach 2:
The gate insulating layer is formed to cover the gate electrode protruding portions before the source and drain electrodes are formed. This preliminary action ensures that the gate insulating layer is already in place and provides insulation coverage before the conductive source/drain electrodes are deposited, preventing short circuits from the beginning of the device operation.
2Reliability
If the gate electrode is spaced from the source and drain electrodes, then short circuits are prevented, but the resistance in the space region increases
Solution Approach 1:
The gate electrode is segmented into a main body and protruding portions. The protruding portions extend toward the source and drain electrodes, reducing the spacing distance and thus the resistance in the space region, while the main body remains spaced to prevent short circuits. This segmentation optimizes both electrical performance and reliability.
Data Source
AI summary
A highly reliable structure is provided when high-speed driving of a semiconductor device is achieved by improving on-state characteristics of the transistor. The on-state characteristics of the transistor are improved as follows: an end portion of a source electrode and an end portion of a drain electrode overlap with end portions of a gate electrode, and the gate electrode surely overlaps with a region serving as a channel formation region of an oxide semiconductor layer. Further, embedded conductive layers are formed in an insulating layer so that large contact areas are obtained between the embedded conductive layers and the source and drain electrodes; thus, the contact resistance of the transistor can be reduced. Prevention of coverage failure with a gate insulating layer enables the oxide semiconductor layer to be thin; thus, the transistor is miniaturized.