Oxide Semiconductor Transistor Layout for Pixel-Driver Speed Balance
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high-speed operation and high display quality with both pixel and driver circuits on a single substrate, as they require conflicting characteristics such as high on/off ratio and high operation speed, which are difficult to reconcile for improved aperture ratio and definition.
Innovation Solution
A semiconductor device is developed with two types of transistors, one for the pixel portion and one for the driver circuit, both featuring oxide semiconductor layers with crystalline regions, where the channel position is selected by the gate electrode layer, and the transistors are optimized for high-speed operation using specific materials and manufacturing processes like rapid thermal annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor is designed for high on/off ratio (pixel portion), then switching characteristics improve, but operation speed decreases
Solution Approach 1:
The patent applies local quality by creating two distinct transistor types with different oxide semiconductor layer structures: one optimized for pixel portions with high on/off ratio requirements, and another optimized for driver circuits with high speed requirements. Each transistor type has tailored channel formation regions and gate structures suited to its specific functional demands.
Solution Approach 2:
The patent segments the semiconductor device into functionally distinct transistor types: pixel transistors and driver circuit transistors. This segmentation allows independent optimization of each transistor type for its specific application, resolving the contradiction between switching characteristics and operation speed by treating them as separate design requirements.
2Manufacturing precision
If aperture ratio is increased to improve display quality, then definition improves, but writing time increases
Solution Approach 1:
The patent changes the parameter of transistor operation speed by implementing driver circuit transistors with optimized oxide semiconductor layers that enable faster switching. This allows the display to refresh more quickly, compensating for the increased writing time associated with higher aperture ratios and improved definition.
3Speed
If high-speed operation is achieved in driver circuit, then operation speed improves, but switching characteristics deteriorate
Solution Approach 1:
The patent applies local quality by designing driver circuit transistors with oxide semiconductor layer structures specifically optimized for high-speed operation, while maintaining separate pixel transistors optimized for switching characteristics. This localized optimization allows each transistor type to excel at its primary function without compromising the other.
4Speed
If oxide semiconductor layer is crystallized to improve field-effect mobility, then operation speed improves, but manufacturing complexity increases
Solution Approach 1:
The patent changes the physical state parameter of the oxide semiconductor layer by introducing crystalline regions within the amorphous matrix. This partial crystallization approach improves field-effect mobility and operation speed while avoiding the need for complete crystallization, thereby limiting the increase in manufacturing complexity to manageable levels.
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 approach enables the manufacturing of semiconductor devices with high-speed driver circuits and reliable pixel portions on a single substrate, enhancing display quality and reliability by optimizing transistor performance and reducing off-state current.
Implementation Method 1
rapid thermal annealing
Implementation Method 2
a first oxide semiconductor layer including a crystalline region including nanocrystals
Data Source
AI summary
An object of an embodiment of the present invention is to manufacture a semiconductor device with high display quality and high reliability, which includes a pixel portion and a driver circuit portion capable of high-speed operation over one substrate, using transistors having favorable electric characteristics and high reliability as switching elements. Two kinds of transistors, in each of which an oxide semiconductor layer including a crystalline region on one surface side is used as an active layer, are formed in a driver circuit portion and a pixel portion. Electric characteristics of the transistors can be selected by choosing the position of the gate electrode layer which determines the position of the channel. Thus, a semiconductor device including a driver circuit portion capable of high-speed operation and a pixel portion over one substrate can be manufactured.