Thin Film Transistor Array Panel Pixel Electrode Lift-Off
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Solution Overview
Problem
Conventional liquid crystal display (LCD) manufacturing processes require numerous photolithography steps, increasing production time and cost, necessitating a method to reduce the number of these processes.
Innovation Solution
A selective lift-off method for forming pixel electrodes on a thin film transistor array panel, which eliminates a photolithography step by using a photosensitive film pattern to expose and remove a passivation layer, allowing for the deposition and subsequent lift-off of a conductive layer to form the pixel electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography processes are used to form pixel electrodes, then manufacturing precision is maintained, but the number of photolithography steps increases production time and cost
Solution Approach 1:
The patent extracts and eliminates one photolithography step from the conventional multi-step process by using a selective lift-off method. The pixel electrode is formed by depositing a conductive layer and then selectively removing it in non-pixel areas using a photosensitive film pattern as mask, rather than forming the electrode pattern through photolithography
Solution Approach 2:
Instead of forming the pixel electrode pattern directly through photolithography (positive approach), the patent uses an inverse approach: deposit a complete conductive layer and then remove the portions that should not be present (negative approach via lift-off). This inversion reduces the number of patterning steps required
2Manufacturing precision
If multiple photolithography processes are used to form pixel electrodes, then manufacturing precision is maintained, but manufacturing cost increases
Solution Approach 1:
The patent merges the pixel electrode formation process with the passivation layer formation process. The photosensitive film pattern serves dual purposes: as a mask for etching the passivation layer and as a mask for the subsequent conductive layer deposition and lift-off, combining multiple functions into a single process sequence
Solution Approach 2:
The patent extracts and eliminates dedicated photolithography steps for pixel electrode formation by using the lift-off method, reducing the total number of photolithography processes from multiple steps to fewer steps, thereby lowering manufacturing cost
3Manufacturing precision
If complex photolithography masking steps are used, then manufacturing precision is maintained, but process complexity increases
Solution Approach 1:
The photosensitive film pattern serves multiple functions: it acts as an etch mask for removing the passivation layer, and subsequently as a lift-off mask for the conductive layer deposition. This multi-functionality eliminates the need for separate photolithography masks and steps for each operation
Solution Approach 2:
The photosensitive film pattern automatically defines the pixel electrode boundaries through the lift-off process. The pattern itself serves as the precise mask without requiring additional photolithography alignment steps, as the conductive layer is deposited conformally and then removed wherever the photosensitive film is present
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
This method simplifies the manufacturing process, reduces the number of photomasks required, and decreases production time and cost while minimizing errors associated with complex masking steps, enabling efficient production of thin film transistor array panels.
Implementation Method 1
coating a photosensitive film on the first passivation layer and exposing the photosensitive film to light using a first photomask to form a first photosensitive film pattern
Implementation Method 2
depositing a conductive layer on the second photosensitive film pattern
Data Source
AI summary
The present disclosure relates to a thin film transistor array panel and a manufacturing method thereof. The method comprises: forming a thin film transistor on a substrate; forming a color filter adjacent to the thin film transistor and over the same substrate; depositing a first passivation layer on the color filter; coating a photosensitive film on the first passivation layer and exposing the photosensitive film to light using a first photomask to form a first photosensitive film pattern that comprises a first portion and a second portion that is thicker than the first portion, the first photosensitive film pattern exposing the first passivation layer around a circumference of the second portion; removing the exposed first passivation layer using the first photosensitive film pattern as an etch mask; blanket etching a whole surface of the first photosensitive film pattern until the first portion is removed to form a second photosensitive film pattern; depositing a conductive layer on the second photosensitive film pattern; and removing the second photosensitive film pattern to thereby selectively lift off portions of the conductive layer where a left behind portion forms a pixel electrode.