Multi-Tone Photomask for TFT Pixel Electrode Manufacturing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional amorphous silicon TFT manufacturing processes require six masks, leading to increased manufacturing time and cost due to the complexity of the photolithography process, which also results in higher chances of photomask misalignment and reduced yield.
Innovation Solution
A semiconductor device manufacturing method using four masks, employing half-tone or gray-tone photomasks to simplify the process, reducing the number of photolithography steps and aligning photomasks, thereby improving manufacturing efficiency and reducing misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If six photomasks are used for conventional amorphous silicon TFT manufacturing, then the manufacturing process can be completed with standard photolithography steps, but the manufacturing time and cost increase significantly
Solution Approach 1:
The patent combines multiple patterning functions into a single photomask by stacking transparent and metal films in specific regions. The multi-tone photomask integrates both the common electrode pattern and gate electrode pattern formation into one exposure step, eliminating the need for separate photomasks and reducing the total number of photolithography cycles from six to four.
Solution Approach 2:
The patent introduces a vertical stacking dimension by forming a stack of transparent conductive film and metal film in specific regions of the photomask. This multi-layer structure creates different transparency levels (multi-tone) that enable complex pattern formation in a single exposure, effectively adding a dimensional aspect to the traditional planar photomask design.
2Manufacturing precision
If six photomasks are used for conventional amorphous silicon TFT manufacturing, then complete pattern formation is achieved, but photomask misalignment issues increase and yield decreases
Solution Approach 1:
The patent merges multiple pattern formation steps into fewer photomask alignments by using multi-tone regions that simultaneously define both common electrode and gate electrode patterns. This reduction in the number of alignment operations from six to four directly decreases the cumulative misalignment error and improves manufacturing yield.
3Ease of manufacture
If standard photolithography with six masks is used, then manufacturing processes are well-established, but manufacturing cost and time increase
Solution Approach 1:
The patent performs preliminary structuring by stacking transparent and metal films in specific regions before the photolithography step. This pre-prepared multi-tone photomask structure enables complex patterns to be formed in fewer exposure steps, reducing the total manufacturing cycle time while maintaining compatibility with existing photolithography equipment and processes.
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 method reduces manufacturing time and cost by minimizing the number of photomask alignments and steps, enhancing the reliability and yield of semiconductor devices by using multi-tone masks for patterning and etching processes.
Implementation Method 1
a light exposure technique using a half-tone photomask or a gray-tone photomask that is a first multi-tone mask
Data Source
AI summary
The number of photomasks is reduced in a method for manufacturing a liquid crystal display device which operates in a fringe field switching mode, whereby a manufacturing process is simplified and manufacturing cost is reduced. A first transparent conductive film and a first metal film are sequentially stacked over a light-transmitting insulating substrate; the first transparent conductive film and the first metal film are shaped using a multi-tone mask which is a first photomask; an insulating film, a first semiconductor film, a second semiconductor film, and a second metal film are sequentially stacked; the second metal film and the second semiconductor film are shaped using a multi-tone mask which is a second photomask; a protective film is formed; the protective film is shaped using a third photomask; a second transparent conductive film is formed; and the second transparent conductive film is shaped using a fourth photomask.