Thin Film Transistor Array Panel Contact Hole Etching
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Solution Overview
Problem
Current thin film transistor array panels face challenges in achieving a high aperture ratio due to the large size of contact holes, which hinder the development of small-sized display panels with high resolution.
Innovation Solution
The implementation of a thin film transistor array panel design that includes a reduced-sized contact hole, achieved by using an overcoat with inorganic materials like silicon nitride or silicon oxide, which allows for precise etching of the color filter and passivation layer to expose the drain electrode, enabling a pixel electrode connection with a contact hole width of 10 micrometers or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the contact hole size is reduced to improve aperture ratio, then the aperture ratio is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The contact hole formation process is segmented into two distinct etching stages: first etching through the color filter layer, then etching through the overcoat layer. This segmentation allows each etching step to be optimized independently, with the first step creating the initial opening and the second step precisely defining the final contact hole dimensions through the overcoat mask, thereby achieving small contact holes with controlled precision
Solution Approach 2:
The overcoat layer is deposited and patterned in advance before the contact hole etching process. This preliminary action creates a precise etching mask that defines the contact hole pattern, enabling subsequent etching steps to achieve the required precision for small contact holes (10 micrometers or less) without directly patterning the sensitive contact hole dimensions
2Area of stationary object
If the contact hole size is reduced to improve aperture ratio, then the aperture ratio is improved, but the device complexity increases
Solution Approach 1:
The overcoat layer serves multiple functions: it acts as a protective barrier during manufacturing, provides a precise etching mask for contact hole formation, and serves as part of the final device structure. This multi-functionality reduces the need for additional dedicated layers or processes, thereby limiting the increase in device complexity despite the enhanced contact hole precision requirements
Solution Approach 2:
The color filter layer and overcoat layer are combined in the contact hole formation process, where the overcoat is deposited over the color filter and both layers are etched together in a coordinated two-step process. This merging allows the contact hole to penetrate both layers simultaneously with controlled dimensions, achieving small contact holes without requiring separate processing steps for each layer
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 design significantly improves the aperture ratio of the thin film transistor array panel by reducing the contact hole size, enhancing the performance of small-sized display panels with high resolution.
Implementation Method 1
performing first dry etching using the photosensitive film pattern as a mask to etch the overcoat
Implementation Method 2
performing second dry etching using the overcoat as a mask to etch the color filter through the preliminary contact hole
Data Source
AI summary
A method of manufacturing a thin film transistor array panel includes: a gate insulating layer disposed on a gate electrode, a semiconductor disposed on the gate insulating layer, a source electrode opposite a drain electrode disposed on the semiconductor, a color filter disposed on the gate insulating layer, an overcoat disposed on the color filter and including an inorganic material. A first dry etching is performed using the photosensitive film pattern as a mask to etch the overcoat and provide a preliminary contact hole, through which a portion of the color filter is exposed. A second dry etching is performed using the overcoat as a mask to etch the color filter through the preliminary contact hole and to provide a contact hole, through which a portion of the drain electrode is exposed. A pixel electrode is connected to the drain electrode through the contact hole, on the overcoat.