Thin Film Transistor Etching Stop Layer for Active Layer Integrity
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Solution Overview
Problem
The etching process for forming source and drain in thin film transistors with metallic element semiconductor active layers damages the active layer region between the source and drain, affecting design requirements and mobility.
Innovation Solution
A method involving the formation of a semiconductor film, an etching stop film, and a source and drain film on a substrate, using a same mask plate to create a pattern with an etching stop layer that electrically connects the source and drain with the active layer, protecting the semiconductor film during etching and ensuring the active layer's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching process is used to form source and drain, then source and drain can be formed, but the active layer region between source and drain is damaged
Solution Approach 1:
An etching stop film is formed on the semiconductor film before the etching process. This preliminary protective layer prevents the etching solution from damaging the active layer region between source and drain, while still allowing the etching to proceed to form the source and drain electrodes.
Solution Approach 2:
The etching stop film acts as an intermediary layer between the semiconductor film and the etching solution. It mediates the etching process by being selectively removed in specific regions to expose the source and drain, while protecting the active layer from direct contact with the etching solution.
2Manufacturing precision
If multiple mask plates are used for patterning, then precise patterning can be achieved, but process complexity and cost increase
Solution Approach 1:
The patent combines multiple patterning functions into a single mask plate. The mask plate is designed with multiple opening regions that simultaneously define the patterns for source, drain, and etching stop layer removal, eliminating the need for multiple sequential masking steps.
Solution Approach 2:
The single mask plate serves multiple functions: it defines the source electrode pattern, defines the drain electrode pattern, and defines the regions where the etching stop film should be removed. This multi-functional mask plate simplifies the overall fabrication process while maintaining patterning precision.
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 protects the semiconductor film from etching damage, maintains the active layer's performance, simplifies the process, and reduces costs by using a single mask plate for patterning.
Implementation Method 1
exposing and developing the photoresist layer by using a gray tone mask plate, to form a first photoresist completely retained region in a region corresponding to a pattern of source to be formed, forming a second photoresist completely retained region in a region corresponding to a pattern of drain to be formed
Implementation Method 2
wet etching the source and drain film for a first time, to retain the source and drain film in a region corresponding to the first photoresist completely retained region, the second photoresist completely retained region, and the photoresist partially retained
Implementation Method 3
dry etching the etching stop film for a first time, to retain the etching stop film in a region corresponding to the first photoresist completely retained region, the second photoresist completely retained region, and the photoresist partially retained
Implementation Method 4
ashing the photoresist layer in the first photoresist completely retained region, the second photoresist completely retained region, and the photoresist partially retained region, to completely remove the photoresist layer in the photoresist partially retained region
Data Source
AI summary
A thin film transistor, a method for fabricating the same, an array substrate, and a display panel are disclosed. The method includes: forming a semiconductor film comprising metallic elements, an etching stop film, and a source and drain film on a substrate in this order; and forming a pattern comprising an active layer, an etching stop layer, and a source and drain on the active layer by using a same mask plate, wherein the etching stop layer electrically connects the source and drain with the active layer. Since an etching stop film is formed on a semiconductor film comprising metallic elements, during etching the metal layer, the etching stop film can protect the semiconductor film comprising metallic elements from being etched, and this ensures the performance of the resultant active layer.