Multi-tone Mask Photolithography for Display Device Manufacturing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing active matrix display devices require a large number of photolithography steps and photomasks, leading to increased complexity, cost, and reduced yield due to the need for complicated techniques like backside light exposure and lift-off methods.
Innovation Solution
The process is simplified by reducing the number of photolithography steps and photomasks through a method where a gate electrode, island-like semiconductor layer, and source/drain electrodes are formed using a multi-tone mask in fewer steps, allowing for the integration of a pixel electrode and counter electrode on one substrate without increasing the number of masks, and using a planarization insulating layer to improve coverage and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional photolithography steps are used to form gate electrode and semiconductor layer separately, then manufacturing precision is maintained, but the number of photomasks and process complexity increase
Solution Approach 1:
The patent combines the formation of the gate electrode and the semiconductor layer into a single photolithography step by using a multi-tone mask. This merging of previously separate processes reduces the total number of photomasks from five or more to three, while the multi-tone mask technology ensures that alignment precision is maintained through simultaneous patterning of multiple layers.
Solution Approach 2:
The multi-tone mask serves multiple functions: it patterns both the gate electrode and the semiconductor layer in a single exposure step, eliminating the need for separate photolithography steps. This multi-functional approach reduces process complexity while maintaining manufacturing precision through integrated patterning.
2Adaptability or versatility
If more photolithography steps are added to form additional layers, then device functionality is improved, but productivity decreases due to increased process steps
Solution Approach 1:
The patent merges the patterning of the gate electrode and semiconductor layer into a single photolithography step using a multi-tone mask. This combination maintains full device functionality while reducing the number of sequential process steps from five or more to three, thereby improving manufacturing efficiency and productivity.
3Ease of manufacture
If conventional techniques like lift-off method are used, then ease of manufacture is improved, but reliability decreases due to yield reduction
Solution Approach 1:
The patent combines multiple patterning steps into a single photolithography process using a multi-tone mask, eliminating the need for complex conventional techniques like lift-off or backside exposure. This integrated approach maintains ease of manufacture while improving reliability by reducing the number of process steps where defects can occur, thereby increasing fabrication yield.
Data Source
AI summary
An object is to reduce the number of photomasks used for manufacturing a transistor and manufacturing a display device to less than the conventional one. The display device is manufactured through, in total, three photolithography steps including one photolithography step which serves as both a step of forming a gate electrode and a step of forming an island-like semiconductor layer, one photolithography step of forming a contact hole after a planarization insulating layer is formed, and one photolithography step which serves as both a step of forming a source electrode and a drain electrode and a step of forming a pixel electrode.