Oxide Semiconductor Gate Structure for High On-State Current
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high on-state current, field-effect mobility, favorable frequency characteristics, electrical reliability, low power consumption, and miniaturization, while maintaining consistent transistor characteristics.
Innovation Solution
A semiconductor device structure is designed with an oxide semiconductor film, source and drain electrodes, interlayer insulating film, gate insulating film, and barrier insulating film, where the barrier insulating film is positioned between the source and gate insulating film and drain and gate electrodes, with a tapered shape and specific materials like silicon nitride and aluminum oxide, and a manufacturing method involving etching and wet etching treatments to form a gate insulating film and gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a transistor is formed using an oxide semiconductor thin film, then leakage current in off state is reduced, but on-state current and field-effect mobility are insufficient
Solution Approach 1:
The patent applies local quality by forming a tapered barrier insulating film with varying thickness - thinner at the gate electrode side and thicker at the source/drain electrode sides. This localized variation in insulating film thickness optimizes different regions: the thinner region at the gate side improves field-effect mobility and on-state current by reducing barrier height, while the thicker regions at the source/drain sides maintain low leakage current by providing sufficient insulation. This resolves the contradiction between low leakage current and high on-state current.
Solution Approach 2:
The patent changes the physical parameter of the barrier insulating film by creating a tapered structure with controlled thickness variation. The film thickness transitions from a maximum value at the source/drain sides to a minimum value at the gate side, forming an inclined or curved profile. This parameter change enables the barrier insulating film to simultaneously provide low resistance contact at the gate interface (improving on-state current) and sufficient barrier height at the source/drain interfaces (reducing leakage current).
2Productivity
If transistor size is reduced for higher density integration, then device miniaturization is achieved, but manufacturing precision and characteristic consistency become difficult to maintain
Solution Approach 1:
The patent applies preliminary action by forming the barrier insulating film with a predetermined tapered shape before subsequent processing steps. The inclined or curved profile is created in advance through selective etching or deposition, establishing a built-in gradient that compensates for variations introduced during miniaturization. This pre-formed structural feature ensures consistent electrical characteristics across scaled-down devices by providing a controlled transition region that reduces sensitivity to dimensional variations.
Solution Approach 2:
The patent employs curvature by forming the barrier insulating film with a tapered, inclined, or curved profile rather than a flat geometry. The curved transition from thick to thin regions creates a gradual change in barrier properties, which smooths out electrical field distributions and reduces hot spots. This curved structure improves manufacturing precision and characteristic consistency in miniaturized transistors by providing a more robust geometry that is less sensitive to lithographic and etching variations.
Data Source
AI summary
A semiconductor device with a high on-state current is provided. An oxide film; a source electrode and a drain electrode over the oxide film; an interlayer insulating film covers the oxide film, the source electrode, and the drain electrode; a gate insulating film over the oxide film; a barrier insulating film over the oxide film; and a gate electrode over the gate insulating film are included. The barrier insulating film is between the source electrode and the gate insulating film and between the drain electrode and the gate electrode. An opening is formed in the interlayer insulating film so as to overlap with a region between the source electrode and the drain electrode. The barrier insulating film, the gate insulating film, and the gate electrode are in the opening. Above the barrier insulating film, the gate insulating film is in contact with the interlayer insulating film.