Oxide Semiconductor Transistor Light Irradiation LDD Region
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Solution Overview
Problem
Transistors with oxide semiconductors in display devices suffer from characteristic deterioration due to electric field concentration and hot carrier injection, leading to shifts in threshold voltage and reliability issues.
Innovation Solution
Incorporating a low-resistance light irradiation region between the channel forming region and the source/drain regions, formed by irradiating light with a luminous intensity of 100 cd/m2 or more, which functions as a lightly doped drain (LDD) region to mitigate electric field concentration and reduce resistance, thereby suppressing characteristic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor with oxide semiconductor is used in display devices, then the transistor can be provided in the pixel circuit of display area, but characteristic deterioration occurs due to electric field concentration and hot carrier injection
Solution Approach 1:
The patent introduces a lightly doped drain (LDD) region with specific doping concentration (1×10^18 to 1×10^20 atoms/cm³) between the channel and source/drain regions. This creates a localized gradient in doping concentration, where the LDD region has intermediate doping between the channel and heavily doped source/drain, thereby reducing electric field concentration at the drain junction and suppressing hot carrier injection while maintaining transistor functionality
Solution Approach 2:
The LDD region is formed prior to the final source/drain contact formation, establishing a protective gradient structure before high-current operation begins. This preliminary structural preparation prevents characteristic deterioration by already having the electric field distribution optimized before the transistor undergoes stress operation
2Reliability
If light irradiation is used to form low-resistance region, then resistance is reduced and electric field concentration is mitigated, but additional manufacturing process step is required
Solution Approach 1:
The patent combines the LDD region formation with the existing light irradiation process used for other purposes in the manufacturing sequence. By integrating multiple functions into a single process step (forming LDD region while simultaneously reducing resistance through light irradiation), the patent reduces overall process complexity compared to adding a separate dedicated LDD formation step
Solution Approach 2:
The light irradiation process serves multiple functions: it forms the low-resistance LDD region, reduces overall contact resistance, and potentially activates dopants. This multi-functionality eliminates the need for separate process steps, thereby reducing manufacturing complexity while achieving multiple beneficial outcomes
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 implementation of a low-resistance LDD region through light irradiation effectively reduces electric field concentration and prevents characteristic deterioration in transistors, enhancing their reliability and performance.
Implementation Method 1
a light irradiation region which is made low-resistance by irradiating light thereto
Data Source
AI summary
According to one embodiment, a transistor includes a first gate electrode, a second gate electrode, an oxide semiconductor layer disposed between the first gate electrode and the second gate electrode, and a source electrode and a drain electrode each connected to the oxide semiconductor layer, wherein the oxide semiconductor layer includes a channel forming region, a source region, and a drain region, a light irradiation region which is made low-resistance by irradiating light thereto is each formed between the channel forming region and the source region and between the channel forming region and the drain region, and the first date electrode and the second gate electrode have different lengths.