Oxide Semiconductor Thin Film Transistor Electrostatic Discharge Protection
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Solution Overview
Problem
Semiconductor devices with thin film transistors face challenges in reliability due to electrostatic breakdown and high power consumption, particularly in portable electronic devices and large television sets, where electrostatic discharge and power efficiency are critical concerns.
Innovation Solution
A semiconductor device is designed with a pixel and driver circuit portion on a single substrate, incorporating a pixel thin film transistor and a driver circuit thin film transistor, both using an oxide semiconductor layer. The structure includes a conductive layer between the gate electrode and oxide semiconductor layer, and a counter electrode layer that overlaps with both portions to manage electrostatic discharge and reduce parasitic capacitance, thereby enhancing reliability and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin film transistor is formed using conventional semiconductor materials, then the device can function as a switching element, but the device is susceptible to electrostatic breakdown and has high power consumption
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor to oxide semiconductor, which fundamentally alters the electrical characteristics to achieve both electrostatic breakdown resistance and low power consumption. The oxide semiconductor layer exhibits wide bandgap characteristics that prevent electrostatic discharge damage while maintaining low leakage current.
Solution Approach 2:
The patent employs a composite structure consisting of multiple oxide semiconductor layers with different compositions and characteristics. The first oxide semiconductor layer has different properties than the second oxide semiconductor layer, creating a composite material system that optimizes both reliability and power consumption characteristics.
2Use of energy by moving object
If an oxide semiconductor layer is used in the thin film transistor, then power consumption is reduced, but threshold voltage variation increases
Solution Approach 1:
The patent applies local quality by creating distinct oxide semiconductor layers with different compositions and properties at different locations within the transistor structure. The first oxide semiconductor layer has specific characteristics optimized for one function, while the second layer has different characteristics optimized for another function, thereby controlling threshold voltage variation while maintaining low power consumption.
Solution Approach 2:
The patent performs preliminary heat treatment on the oxide semiconductor layers before final device operation. This preliminary action stabilizes the threshold voltage by removing moisture and volatile components, ensuring consistent electrical characteristics while preserving the low power consumption benefits of the oxide semiconductor material.
3Stability of the object's composition
If dehydratation and dehydrogenation treatments are applied to the oxide semiconductor layer, then electric characteristics are stabilized, but manufacturing process complexity increases
Solution Approach 1:
The patent combines the dehydratation and dehydrogenation treatments into a single integrated heat treatment process step. By merging these two stabilization treatments into one process, the patent achieves electric characteristics stability while minimizing the increase in manufacturing process complexity.
Solution Approach 2:
The patent performs dehydratation and dehydrogenation treatments in an inert atmosphere environment, which prevents oxidation and contamination during the heat treatment process. This approach stabilizes electric characteristics while keeping the manufacturing process relatively simple by using a standard inert atmosphere rather than requiring complex controlled environments.
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 semiconductor device with improved reliability against electrostatic breakdown and reduced power consumption, enabling stable electric characteristics and efficient operation in electronic devices.
Implementation Method 1
dehydration/dehydrogenation treatments
Implementation Method 2
dehydration/dehydrogenation treatments
Implementation Method 3
the counter electrode layer diffuses static electricity applied by electrostatic discharge and prevents local electric charges (localization of electric charges)
Data Source
AI summary
Disclosed is a semiconductor device which consumes low power and has high reliability and tolerance for electrostatic discharge. The semiconductor device includes, over a first substrate, a pixel portion and a driver circuit portion both of which have a thin film transistor having an oxide semiconductor layer. The semiconductor device further possesses a second substrate to which a first counter electrode layer and a second counter electrode layer are provided, and a liquid crystal layer is interposed between the first and second substrates. The first and second counter electrode layers are provided over the pixel portion and the driver circuit portion, respectively, and the second counter electrode layer has the same potential as the first counter electrode layer.