Oxide Semiconductor Transistor Stress Layout for Stable Characteristics
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving small variation in transistor characteristics, favorable reliability, favorable electrical characteristics, high on-state current, miniaturization, high integration, and low power consumption.
Innovation Solution
A transistor is designed with an oxide semiconductor film, source and drain electrodes with compressive stress, and a gate electrode positioned over the oxide semiconductor film, with an opening in the interlayer insulating film to overlap with the region between the source and drain electrodes, and a barrier insulating film containing silicon nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor is formed using conventional semiconductor materials and structures, then manufacturing processes are well-established, but transistor characteristics show large variation and reliability is insufficient
Solution Approach 1:
The patent applies parameter changes by introducing compressive stress to the source and drain electrodes, which induces tensile stress in the oxide semiconductor film. This stress engineering modifies the electrical characteristics of the transistor, improving on-state current and threshold voltage stability, thereby reducing characteristic variation and enhancing reliability
Solution Approach 2:
The patent uses composite materials by combining oxide semiconductor film with specific electrode materials (such as tungsten or molybdenum) that generate compressive stress. This composite structure leverages the beneficial properties of both materials: the oxide semiconductor provides low leakage current while the stress-generating electrode material improves carrier mobility and characteristic consistency
2Productivity
If transistor size is reduced for miniaturization and high integration, then device density increases, but maintaining favorable electrical characteristics and high on-state current becomes difficult
Solution Approach 1:
The patent employs stress engineering as a parameter change technique to decouple device scaling from performance degradation. By introducing compressive stress in electrodes that induces tensile stress in the channel region, the patent maintains high carrier mobility and on-state current even as device dimensions are reduced, enabling miniaturization without sacrificing electrical characteristics
Solution Approach 2:
The patent applies local quality by creating non-uniform stress distribution within the transistor structure. The compressive stress is localized in the source and drain electrodes, which then translates to tensile stress specifically in the oxide semiconductor channel region. This localized stress application improves carrier mobility where needed without affecting other parts of the device, maintaining performance during miniaturization
3Loss of energy
If oxide semiconductor transistors are used to achieve low leakage current, then power consumption decreases, but achieving high on-state current and favorable electrical characteristics simultaneously is challenging
Solution Approach 1:
The patent uses stress engineering to modify the electrical parameters of the oxide semiconductor. By inducing tensile stress through compressive electrode stress, the patent increases carrier mobility and adjusts threshold voltage, thereby achieving high on-state current while maintaining the inherently low leakage current of oxide semiconductors. This parameter modification resolves the trade-off between off-state and on-state performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a semiconductor device with small variation in transistor characteristics, favorable reliability, favorable electrical characteristics, high on-state current, miniaturization, high integration, and low power consumption.
Implementation Method 1
the source electrode and the drain electrode have compressive stress
Implementation Method 2
a barrier insulating film containing silicon nitride
Data Source
AI summary
A semiconductor device with a small variation in transistor characteristics is provided. An oxide semiconductor film, a source electrode and a drain electrode over the oxide semiconductor film, an interlayer insulating film placed to cover the oxide semiconductor film, the source electrode, and the drain electrode, and a gate electrode over the oxide semiconductor film are included; an opening is formed overlapping with a region between the source electrode and the drain electrode in the interlayer insulating film; the gate electrode is placed in the opening in the interlayer insulating film; and the source electrode and the drain electrode include a conductive film having compressive stress.