Active Matrix Substrate Surface Roughening for I-V S Value
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Solution Overview
Problem
Current active matrix substrates for organic electroluminescence (EL) display devices face challenges in achieving a gentle slope of I-V characteristics, which is essential for effective gray scale control, as existing manufacturing methods cannot create sufficient irregularities on the semiconductor film surface to disrupt crystal arrangements and increase the S value.
Innovation Solution
A method involving the application of a resist on the underlayer inorganic insulating film, followed by a first ashing process to form irregularities, and subsequent second ashing and etching processes to roughen the underlayer surface, allowing the semiconductor film to be formed with a roughened surface that disrupts crystal arrangements, thereby increasing the S value of I-V characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an ordinary etching process or an ordinary ashing process is performed on the underlayer inorganic insulating film, then the film is uniformly reduced, but it is not possible to make the surface rough to a degree that disrupts the crystal arrangement of the semiconductor film
Solution Approach 1:
The patent divides the surface treatment process into multiple stages: first applying a resist film to the underlayer inorganic insulating film, then performing a first ashing process to remove part of the resist and create initial irregularities, followed by a second ashing process and etching process to further roughen the surface. This segmentation allows achieving the required surface roughness that ordinary single-step processes cannot accomplish.
Solution Approach 2:
The patent applies a resist film as a preliminary layer before performing the ashing and etching processes. This resist film serves as a sacrificial layer that enables controlled roughening of the underlayer inorganic insulating film surface. The preliminary application of resist allows subsequent processes to create the necessary surface irregularities without directly attacking the inorganic film in an uncontrolled manner.
2Reliability
If the surface of the underlayer inorganic insulating film is made rough to disrupt crystal arrangement, then the S value of I-V characteristics increases, but the manufacturing process becomes more complex
Solution Approach 1:
The patent changes the surface morphology parameter of the underlayer inorganic insulating film by introducing controlled roughness through the multi-step ashing and etching process. This parameter change (from smooth to rough surface) directly affects the crystal arrangement of the semiconductor film, disrupting it to increase the S value of I-V characteristics and improve gray scale control performance.
Solution Approach 2:
The patent uses the resist film as an intermediary material to achieve the desired surface roughness. The resist film mediates between the manufacturing process and the underlayer inorganic insulating film, allowing controlled roughening through ashing and etching processes that would be difficult to apply directly to the inorganic film without compromising its integrity.
3Ease of operation
If the semiconductor film surface is roughened to increase resistance, then current flow is reduced for better gray scale control, but the process requires additional ashing and etching steps
Solution Approach 1:
The patent changes the electrical parameter of the semiconductor film by roughening its surface. The increased surface roughness increases the resistance of the semiconductor film, which reduces current flow for a given voltage. This parameter change enables better gray scale control in the organic EL display device, allowing more precise control of display brightness levels.
Solution Approach 2:
The patent segments the surface roughening process into distinct stages (first ashing, second ashing, etching) to achieve the required resistance increase in the semiconductor film. This segmented approach allows precise control over the degree of roughness and resulting resistance, optimizing gray scale control while managing the additional process steps required.
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 approach effectively increases the S value of I-V characteristics, resulting in a gentler slope that is advantageous for gray scale control in organic EL display devices.
Implementation Method 1
performing an ashing process of forming a surface having irregularities on a surface of the resist by a first ashing process
Implementation Method 2
performing a second ashing process and an etching process on the underlayer inorganic insulating film
Implementation Method 3
performing a second ashing process and an etching process on the underlayer inorganic insulating film
Data Source
AI summary
In a method for manufacturing an active matrix substrate, forming of an underlayer inorganic insulating film includes applying a resist onto the underlayer inorganic insulating film, performing an ashing process of forming a surface having irregularities on a surface of the resist by a first ashing process, and, after the ashing process has been performed, roughening a surface of the underlayer inorganic insulating film by performing a second ashing process and an etching process on the underlayer inorganic insulating film. When forming a semiconductor film, a surface of at least a part of the semiconductor film is roughened following a rough surface of the underlayer inorganic insulating film.