LTPS Display TFT Structure Using Oxide Contact for Higher Mobility
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving high electron mobility and improved electrical characteristics in thin film transistors, particularly due to limitations in polysilicon active patterns and the integration of oxide semiconductor patterns.
Innovation Solution
The display apparatus incorporates a polysilicon active pattern with direct contact to an oxide semiconductor pattern, formed using a low temperature polysilicon (LTPS) process, where the oxide semiconductor pattern affects the polysilicon active pattern separately from impurity doping, enhancing electron mobility and electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polysilicon active pattern is used in thin film transistors, then the device structure is simple and manufacturing is easier, but electron mobility and electrical characteristics are insufficient
Solution Approach 1:
The patent combines polysilicon and oxide semiconductor materials to form a composite active pattern. The polysilicon portion provides good electrical characteristics and mobility, while the oxide semiconductor portion contributes to threshold voltage control and device stability. This composite structure resolves the contradiction by achieving high electron mobility through material composition rather than structural complexity.
Solution Approach 2:
The active pattern is divided into different regions with different materials: polysilicon in areas requiring high electron mobility and oxide semiconductor in areas requiring threshold voltage control. This local differentiation allows each material to contribute its superior properties to specific functional regions, improving overall device performance without requiring complex global structural changes.
2Reliability
If oxide semiconductor pattern is integrated with polysilicon active pattern, then electrical characteristics are improved, but manufacturing process becomes more complex
Solution Approach 1:
The oxide semiconductor layer is formed and positioned in advance during the active pattern formation process, before final device assembly. This preliminary integration allows the oxide semiconductor to be pre-aligned with the polysilicon regions, simplifying subsequent manufacturing steps while achieving the desired electrical characteristics through the pre-established material configuration.
3Power
If polysilicon transistor is used for driving, then driving capability is sufficient, but electron mobility is limited compared to oxide semiconductor
Solution Approach 1:
The patent merges the advantages of polysilicon transistors (high driving capability) with oxide semiconductor transistors (high electron mobility) by creating a unified active pattern where both materials coexist. The polysilicon region handles high current driving requirements while the oxide semiconductor region provides high mobility channels, achieving both driving capability and electron mobility in a single device structure.
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
This configuration improves electron mobility and electrical characteristics of the thin film transistor, leading to enhanced display quality by utilizing a polysilicon transistor for driving, an oxide semiconductor transistor for switching, and a polysilicon transistor with improved mobility for circuit constitution.
Implementation Method 1
the oxide semiconductor pattern affects the polysilicon active pattern separately from impurity doping, enhancing electron mobility and electrical characteristics
Data Source
AI summary
A display apparatus includes a base substrate, a polysilicon active pattern disposed on the base substrate, including polycrystalline silicon, including a source region and a drain region each doped with impurities and a channel region between the source region and the drain region, and including indium, a first gate electrode overlapping the channel region, and a source electrode electrically connected to the source region and a drain electrode electrically connected to the drain region.