Back-Gate Transistor Stress Relief in Semiconductor Shift Registers
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Solution Overview
Problem
Thin film transistors with amorphous semiconductor channel regions face deterioration issues such as increased threshold voltage and decreased field-effect mobility, leading to operational failures in driver circuits, particularly in large display devices like liquid crystal televisions, which affects the reliability and productivity of semiconductor devices.
Innovation Solution
A semiconductor device incorporating a shift register with pulse output circuits using transistors having the same conductivity type, where a transistor with a back gate is employed to relieve stress by interchanging gate and back gate potentials during non-selection periods, and capacitors are strategically connected to maintain stable node potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin film transistors with amorphous semiconductor channel regions are used in driver circuits, then cost is reduced and integration is improved, but transistor deterioration occurs leading to increased threshold voltage and decreased field-effect mobility
Solution Approach 1:
The invention applies dynamic stress relief by periodically interchanging the potentials of the gate and back gate in non-selection periods. This dynamic potential interchange prevents permanent transistor deterioration by relieving accumulated stress, thereby maintaining transistor characteristics while using amorphous semiconductor TFTs in integrated driver circuits
Solution Approach 2:
The invention changes the electrical parameters (potentials) of the gate and back gate dynamically. By interchanging the potentials between selection and non-selection periods, the transistor operates under different electrical conditions that prevent degradation, thus maintaining reliability while using cost-effective amorphous semiconductor TFTs
2Productivity
If transistors operate continuously in selection periods, then driver circuit functionality is maintained, but stress accumulates causing transistor deterioration
Solution Approach 1:
The invention implements periodic stress relief by alternating between selection periods (where transistors perform their driving function) and non-selection periods (where potential interchange relieves stress). This periodic action allows the driver circuit to maintain functionality while preventing transistor deterioration through regular stress relief cycles
Solution Approach 2:
The invention applies preliminary anti-action by proactively relieving stress during non-selection periods before transistor deterioration can occur. The potential interchange in advance prevents the accumulation of damaging stress, thereby protecting transistor durability while maintaining continuous driver circuit operation
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 provides a highly reliable semiconductor device with improved productivity and low power consumption, reducing the likelihood of transistor degradation and ensuring stable operation of the shift register.
Implementation Method 1
In the non-selection period, by interchanging the potentials of the gates and those of the back gates, stress applied to the transistors can be relieved
Data Source
AI summary
A highly reliable semiconductor device is provided. A semiconductor device includes a shift register including a pulse output circuit formed using transistors having the same conductivity type, or the like. A transistor including a back gate is used as a transistor in which a potential difference between a source and a drain is not generated and positive stress is applied to a gate in a non-selection period of the pulse output circuit. In the non-selection period, stress applied to the transistors is reduced by interchanging the potentials of the gates and those of the back gates.