LTPS-LCD Transparent Electrode Capacitance Mask Reduction
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Solution Overview
Problem
Conventional LTPS-LCD manufacturing processes require six masks for photolithography, leading to reduced capacitance due to undoped poly-silicon islands and increased manufacturing costs.
Innovation Solution
The LTPS-LCD structure incorporates a transparent electrode on the substrate, with a silicon-oxide insulator layer and conductive layers formed in a simplified photolithography process, reducing the number of masks needed and enhancing capacitance by forming effective capacitance in the un-doped poly-silicon area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional LTPS photolithography manufacturing processes are used with six masks, then complete doping coverage is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The transparent electrode is formed on the substrate before the poly-silicon layer is deposited. This preliminary positioning allows the electrode to serve as a foundation for subsequent capacitance formation without requiring additional doping steps or masks in the conventional photolithography process.
Solution Approach 2:
The transparent electrode positioned at the bottom of the display structure serves multiple functions: it acts as an electrical contact and simultaneously forms part of the capacitance storage device by creating capacitance with the un-doped poly-silicon island. This eliminates the need for separate capacitance structures that would require additional masks.
2Reliability
If poly-silicon islands are used for capacitance storage, then capacitance is provided, but the islands must be doped which reduces effective capacitance
Solution Approach 1:
Instead of doping the poly-silicon island to create capacitance (conventional approach), the invention inverts the approach by leaving the poly-silicon island un-doped and forming capacitance between the transparent electrode and the un-doped island. This inversion preserves the high carrier mobility of un-doped LTPS while still achieving capacitance storage.
Solution Approach 2:
The transparent electrode positioned at the bottom serves as an intermediary element that enables capacitance formation with the un-doped poly-silicon island. This intermediary structure allows capacitance storage without requiring doping of the poly-silicon island, thus maintaining the electrical characteristics of un-doped LTPS.
3Manufacturing precision
If six masks are used for photolithography, then complete structure formation is achieved, but manufacturing cost increases
Solution Approach 1:
The invention merges the function of the transparent electrode formation with the capacitance storage device formation. By positioning the transparent electrode at the bottom before poly-silicon deposition, the electrode serves both as an electrical contact and as part of the capacitance structure, eliminating the need for separate capacitance formation steps and reducing mask requirements.
Solution Approach 2:
The transparent electrode is formed in advance before the poly-silicon layer deposition. This preliminary action allows the electrode to be integrated into the final structure without requiring additional photolithography masks, thereby simplifying the manufacturing process and reducing costs.
Data Source
AI summary
An LTPS-LCD structure and a method for manufacturing the structure are provided. The structure comprises a substrate where a plurality of pixels are formed thereon. Each of these pixels comprises a control area, a capacitance area, and a display area. The structure is initially formed with a transparent electrode on the substrate, followed by a control device, a capacitance storage device. The display unit is then formed on the control area, the capacitance area, and the display area, respectively. As a result, the capacitance of the structure can be enhanced and the manufacturing processes of masks can be reduced.