Transflective LCD Panel Storage Capacitor and Aperture Ratio
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Solution Overview
Problem
Conventional transflective LCD panels require complex and time-consuming fabrication processes, involving multiple photolithographic steps, which complicate the definition of semiconductor layers, electrodes, and dielectric layers, leading to height gaps between reflection and transmission regions that hinder alignment and cell gap control.
Innovation Solution
A transflective LCD panel design that simplifies the process by using a polycrystalline silicon layer, insulating layers, and metal layers with reduced photolithographic steps, forming a storage capacitor beneath the data line and positioning the reflection electrode over the TFT, thereby improving the aperture ratio and simplifying the manufacturing process to seven photolithographic steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithographic processes are used to define semiconductor layers, electrodes, and dielectric layers, then the manufacturing precision is improved, but the device complexity and manufacturing time increase
Solution Approach 1:
The patent merges the definition of multiple layers (semiconductor layer, source/drain electrodes, gate electrode, dielectric layers) into a single photolithographic process step. By using a multi-layer photomask structure, all these components are patterned simultaneously in one exposure and development cycle, eliminating the need for multiple separate photolithographic steps while maintaining precise alignment and definition of each layer.
Solution Approach 2:
The photomask is designed with multi-functionality to perform multiple patterning tasks in one step. It includes transparent regions for defining semiconductor layers, opaque regions for defining electrodes, and specific pattern regions for defining dielectric layer features. This universal photomask replaces multiple specialized photomasks, simplifying the fabrication process while maintaining manufacturing precision.
2Manufacturing precision
If multiple photolithographic processes are used to define semiconductor layers, electrodes, and dielectric layers, then the manufacturing precision is improved, but the production time increases
Solution Approach 1:
The patent combines multiple sequential photolithographic processes into a single parallel process step. By using a multi-layer photomask that simultaneously defines semiconductor layers, electrodes, and dielectric layers, the fabrication time is reduced from multiple exposure-development cycles to one unified process, directly addressing the time loss issue.
Solution Approach 2:
The photomask is prepared in advance with all necessary pattern regions (transparent regions, opaque regions, pattern regions) pre-configured to define all required layers. This preliminary preparation of the multi-functional photomask enables the subsequent single-step exposure to achieve what would otherwise require multiple sequential steps, significantly reducing production time.
3Ease of manufacture
If a second inter-layer dielectric layer is formed only in the reflection region, then the reflection region structure is optimized, but height gaps are created between reflection and transmission regions
Solution Approach 1:
The patent applies local quality by forming the second inter-layer dielectric layer selectively only in the reflection region, not in the transmission region. This localized dielectric layer optimization improves the reflection region structure and performance while the patent simultaneously uses a common first inter-layer dielectric layer across both regions to maintain a uniform reference plane, thereby preventing height gaps and alignment issues.
4Ease of manufacture
If the reflection electrode is positioned in the reflection region only, then the reflection function is optimized, but the aperture ratio is reduced
Solution Approach 1:
The patent makes the reflection electrode multi-functional by extending it from the reflection region into the transmission region. This extended reflection electrode serves dual purposes: maintaining the reflection function in the reflection region and increasing the effective aperture area in the transmission region. The electrode's extended configuration allows it to participate in both reflection and transmission modes, optimizing overall display performance.
Data Source
AI summary
A method of forming a transflective LCD panel is provided. The transflective LCD includes a substrate, a first polycrystalline silicon pattern disposed in a reflection region, a second polycrystalline silicon pattern disposed in a peripheral region, an insulating layer disposed on the first and second polycrystalline silicon pattern and the substrate, a gate electrode disposed in the reflection region, a common electrode disposed in the peripheral region, a first inter-layer dielectric disposed on the insulating layer, the gate electrode and the common electrode, a reflection electrode disposed on the first inter-layer dielectric, a second inter-layer dielectric disposed on the first inter-layer dielectric and the reflection electrode, and a transmission electrode disposed on the second inter-layer dielectric and electrically connected to the reflection electrode through an opening of the second inter-layer dielectric. The second polycrystalline silicon pattern, the common electrode, and the insulating layer disposed therebetween form a storage capacitor.