Metal Pattern Formation Using Halftone Mask and Soft-Baking
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Solution Overview
Problem
The high cost of dry etching processes and the need for multiple masks in forming metal patterns for liquid crystal display apparatuses, which complicates and expenses the manufacturing of display substrates.
Innovation Solution
A method of forming a metal pattern that skips the dry etching process by using a halftone mask to create a photo pattern with varying thicknesses, where the area overlapping the gate electrode has a thickness of 0.1 μm to 0.2 μm, and utilizing soft-baking and ultraviolet exposure to develop the pattern, allowing for the formation of source and drain electrodes without the need for dry etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry etching process is used to remove thin areas of the photo pattern, then the metal pattern can be formed with precise thickness control, but the manufacturing cost increases significantly
Solution Approach 1:
The patent extracts and removes only the thinnest portions of the photo pattern (0.1-0.2 μm areas) that overlap with the gate electrode, rather than using a complete dry etching process. This selective removal approach achieves the necessary thickness differentiation while avoiding the high costs associated with full dry etching operations.
Solution Approach 2:
The patent employs a disposable halftone mask with varying transparency regions instead of requiring multiple expensive masks. The halftone mask creates the initial thickness variation in the photo pattern, which then allows for simplified subsequent processing to achieve the final metal pattern without costly dry etching.
2Manufacturing precision
If multiple masks are used to form the metal pattern, then the pattern precision can be maintained, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the functions of multiple masks into a single halftone mask that contains both slit areas and transparent areas. This consolidated mask design creates the necessary pattern differentiation in one step, eliminating the need for sequential masking operations and reducing overall process complexity.
Solution Approach 2:
The halftone mask serves multiple functions simultaneously: it defines the overall pattern geometry, creates thickness variations in the photo pattern, and enables selective exposure regions. This multi-functional mask reduces the total number of masking steps required while maintaining pattern 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 approach simplifies the process of forming metal patterns, reduces costs, and enables the efficient manufacturing of display substrates by eliminating the dry etching step, thereby decreasing process expenses and improving efficiency.
Implementation Method 1
The photo pattern may be soft-baked within a temperature range of about 80° C. to about 120° C.
Implementation Method 2
The photo pattern may be exposed to an amount of ultraviolet light with energy of about 40 mJ to about 60 mJ.
Data Source
AI summary
A method of forming a metal pattern is disclosed. According to the method, a gate electrode and a pixel electrode are formed on a substrate. A metal layer is formed covering the gate electrode and the pixel electrode. A photo pattern is formed wherein a thickness of an area of the photo pattern that overlaps the gate electrode is smaller than a thickness of other areas of the photo pattern. The photo pattern is soft-baked. The photo pattern is exposed to light. The photo pattern is developed to expose a portion of the metal layer that overlaps the gate electrode. The exposed portion of the metal layer is removed to form a source electrode and a drain electrode, the source electrode and the drain electrode being spaced apart from each other with respect to the gate electrode.