Transparent Pixel Capacitor Structure for High-Aperture Semiconductor Displays
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high aperture ratio, increased charge capacity of capacitors, reduced number of masks in photolithography steps, low off-state current, low power consumption, and high reliability, while maintaining image quality and reducing power consumption.
Innovation Solution
A semiconductor device is designed with a light-transmitting capacitor using an oxide semiconductor layer as one electrode and a light-transmitting conductive film as the other, along with a dielectric formed by multiple insulating films, allowing for increased capacitor area without reducing the aperture ratio and utilizing a transparent semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of the light-blocking conductive film is increased to increase the capacitor area, then the charge capacity of the capacitor is improved, but the aperture ratio of the pixel decreases
Solution Approach 1:
The patent applies the principle of optical property changes by using a light-transmitting conductive film instead of a conventional light-blocking metal film for the capacitor electrode. This transparent conductive film allows light to pass through the capacitor region, maintaining high aperture ratio while providing sufficient charge capacity through its conductive properties. The film is formed in the same region as the semiconductor layer to create the capacitor structure without blocking light.
Solution Approach 2:
The patent employs composite material structure by combining the light-transmitting conductive film with the semiconductor layer to form the capacitor. The conductive film serves dual purposes as both the capacitor electrode and a transparent conductive element, while the semiconductor layer provides both transistor function and capacitor electrode function. This composite approach allows the capacitor to achieve sufficient charge capacity without requiring large area of light-blocking material.
2Device complexity
If a light-blocking metal film is used to form the capacitor electrode, then the capacitor structure is simple, but the aperture ratio decreases and display quality degrades
Solution Approach 1:
The patent changes the optical property of the capacitor electrode from light-blocking to light-transmitting by using a transparent conductive film. This maintains the simplicity of the capacitor structure (single film formation step) while eliminating the light-blocking issue that degrades display quality and reduces aperture ratio.
Solution Approach 2:
The light-transmitting conductive film serves multiple functions: it acts as the capacitor electrode, provides light transmission for display, and maintains electrical conductivity. This multi-functionality replaces the need for separate light-blocking metal films while achieving the same capacitor formation purpose with improved optical properties.
3Quantity of substance
If the area of the capacitor is increased to increase charge capacity, then the capacitance value is improved, but the number of masks in photolithography steps increases
Solution Approach 1:
The patent merges the capacitor formation process with the transistor formation process by forming the light-transmitting conductive film in the same region that serves as the semiconductor layer for the transistor. This combined approach allows the capacitor to achieve sufficient area and charge capacity without requiring additional photolithography mask steps, as the same film formation process creates both structures.
Data Source
AI summary
A semiconductor device with high aperture ratio is provided. The semiconductor device includes a transistor and a capacitor having a pair of electrodes. An oxide semiconductor layer formed over the same insulating surface is used for a channel formation region of the transistor and one of the electrodes of the capacitor. The other electrode of the capacitor is a transparent conductive film. One electrode of the capacitor is electrically connected to a wiring formed over the insulating surface over which a source electrode or a drain electrode of the transistor is provided, and the other electrode of the capacitor is electrically connected to one of the source electrode and the drain electrode of the transistor.