Semiconductor Device Electrode Segmentation for Current and Resistance
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Solution Overview
Problem
Transistors using oxide semiconductors face challenges in increasing on-state current due to high contact resistance and difficulty in miniaturization, as they lack established techniques for valence electron control and require specific electrode configurations to maintain electric field integrity.
Innovation Solution
A semiconductor device structure with a pair of first conductive films under an insulating surface, a semiconductor film, and a pair of second conductive films connected to the first, with a third conductive film overlapping the semiconductor film, allowing for controlled channel length and reduced contact resistance, enabling miniaturization without interrupting the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of source electrode and drain electrode is decreased to ensure step coverage with semiconductor film, then the coverage is improved, but the resistance of source electrode and drain electrode increases
Solution Approach 1:
The source electrode and drain electrode are divided into multiple layers (first conductive film and second conductive film). The first conductive film provides good step coverage with the semiconductor film, while the second conductive film provides low resistance and connects to external circuits. This segmentation allows each layer to optimize for its specific function without compromise.
Solution Approach 2:
The electrode structure uses composite material configuration with different conductive films having different properties. The first conductive film is designed for optimal adhesion and coverage, while the second conductive film is designed for optimal electrical conductivity. This composite approach allows simultaneous achievement of good coverage and low resistance.
2Productivity
If the gap between source electrode and drain electrode is shortened to miniaturize transistor, then the device size is reduced, but the electric field may be interrupted by the electrodes
Solution Approach 1:
The electrode structure extends in the vertical dimension with the first conductive film positioned to ensure proper spacing. By utilizing the vertical dimension for electrode configuration, the horizontal gap can be minimized for miniaturization while maintaining electric field integrity through proper vertical positioning and insulation.
Solution Approach 2:
The first conductive film acts as an intermediary structure between the source and drain regions. It provides a controlled interface that maintains proper electric field distribution while allowing the overall device to be miniaturized. The insulating film also serves as an intermediary to prevent field interruption.
3Device complexity
If oxide semiconductor transistor uses direct connection of conductive film to channel formation region, then the structure is simplified, but the contact resistance becomes high
Solution Approach 1:
The direct connection structure is segmented into multiple conductive films. The first conductive film provides the connection interface with the channel formation region, while the second conductive film provides the external connection. This segmentation allows optimization of each interface for its specific function, reducing contact resistance while maintaining structural clarity.
Data Source
AI summary
Provided is a semiconductor device including a transistor with large on-state current even when it is miniaturized. The transistor includes a pair of first conductive films over an insulating surface; a semiconductor film over the pair of first conductive films; a pair of second conductive films, with one of the pair of second conductive films and the other of the pair of second conductive films being connected to one of the pair of first conductive films and the other of the pair of first conductive films, respectively; an insulating film over the semiconductor film; and a third conductive film provided in a position overlapping with the semiconductor film over the insulating film. Further, over the semiconductor film, the third conductive film is interposed between the pair of second conductive films and away from the pair of second conductive films.