Silicon Nitride Passivation Layers to Prevent PV Undercut
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Solution Overview
Problem
The manufacturing of liquid crystal panels often results in Passivation Undercut (PV Undercut) during the formation of contact holes in the passivation layer, leading to dark spots and abnormal displays.
Innovation Solution
A manufacturing method for a silicon nitride thin film using atomic layer deposition, involving multiple layers with controlled thicknesses, specifically a first silicon nitride layer with a lower etch rate, and subsequent layers with higher etch rates, to form a passivation layer that minimizes PV Undercut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer passivation structure is used, then the manufacturing process is simple, but Passivation Undercut occurs causing dark spots and display abnormalities
Solution Approach 1:
The passivation layer is divided into multiple silicon nitride sub-layers with different thicknesses and etch rates. The first silicon nitride layer has a lower etch rate to prevent undercut, while subsequent layers have higher etch rates to complete the contact hole formation. This segmentation resolves the contradiction by maintaining both manufacturing feasibility and display quality.
Solution Approach 2:
Different regions of the passivation layer are assigned different etch rates through varying the composition or thickness of individual silicon nitride layers. The first layer is specifically designed with lower etch resistance at the contact hole region to prevent undercut, while maintaining overall passivation functionality. This local differentiation resolves the contradiction between simple manufacturing and reliable display performance.
2Length of stationary object
If the passivation layer thickness is reduced to meet cell gap requirements, then the cell gap specification is satisfied, but the film becomes prone to breakage
Solution Approach 1:
The passivation layer is constructed as a composite structure with multiple silicon nitride layers having different thicknesses and etch rates. The first layer provides mechanical strength and undercut prevention, while subsequent layers contribute to the overall thin profile needed for cell gap requirements. This composite approach resolves the contradiction between meeting cell gap specifications and maintaining film integrity.
Solution Approach 2:
The etch rate parameter is varied across different silicon nitride layers to achieve both thin overall thickness for cell gap compliance and sufficient mechanical strength. By controlling the etch rate of the first layer to be lower than subsequent layers, the structure maintains integrity while achieving the required thin profile.
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 effectively reduces the occurrence of dark spots and ensures high-quality display panels by accurately controlling the thickness and uniformity of the silicon nitride thin films, thereby preventing passivation layer breakage.
Implementation Method 1
The silicon nitride thin film is manufactured by an atomic layer deposition technology
Data Source
AI summary
A manufacturing method of a silicon nitride thin film, a thin film transistor, and a display panel are disclosed, the method including: providing a silane precursor into an atomic layer deposition apparatus for a preset time period, and remaining the silane precursor for a preset time period; providing an inert gas thereinto for a preset time period for the first time, and purging the silane precursor; providing a nitrogen supplying precursor for a preset time period, and remaining the nitrogen supplying precursor for a preset time period; providing the inert gas for a preset time period for the second time, and purging the nitrogen supplying precursor; repeating for a preset number of times the steps of providing the silane precursor, providing the inert gas for the first time, providing the nitrogen supplying precursor and providing the inert gas for the second time to form the silicon nitride thin film.