Two-Block Laser Mask for Uniform Polysilicon Crystallization
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Solution Overview
Problem
Existing laser crystallization methods for polycrystalline silicon thin films often result in shot marks due to laser beam overlap, which can lead to non-uniform crystallization and reduced process efficiency.
Innovation Solution
A two-block laser mask is used, with each block having a reverse pattern of the other, allowing for two-shot crystallization of active regions without overlap, utilizing first and second mask patterns to irradiate laser beams and prevent shot marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser mask is used for crystallization, then the process is simple, but shot marks occur due to laser beam overlap
Solution Approach 1:
The laser mask is divided into multiple blocks (first block and second block), each responsible for crystallizing specific regions. The first block crystallizes first active regions, while the second block crystallizes second active regions, preventing laser beam overlap and shot marks through spatial segmentation of the crystallization process
Solution Approach 2:
The patent introduces a block dimension to the mask structure, organizing crystallization regions into distinct blocks. This dimensional organization allows simultaneous or sequential processing of different regions without interference, solving the shot mark problem by distributing laser irradiation across multiple spatial zones
2Manufacturing precision
If laser beams are irradiated to cover all active regions, then complete crystallization is achieved, but shot marks occur due to beam overlap
Solution Approach 1:
Active regions are segmented into first active regions and second active regions, which are crystallized by separate laser beams through different blocks. This segmentation ensures complete coverage of all active regions while preventing shot marks by assigning distinct laser paths to different regions
Solution Approach 2:
Instead of using a single laser beam to cover all regions (which causes overlap), the patent inverts the approach by using multiple laser beams with non-overlapping paths, where the first laser beam covers first active regions and the second laser beam covers second active regions, eliminating the shot mark harmful effect
3Productivity
If conventional laser crystallization is used, then the process is fast, but electrical characteristics are reduced due to shot marks
Solution Approach 1:
The crystallization process is segmented into multiple independent laser irradiation steps through different blocks, maintaining fast processing speed while eliminating shot marks. Each block's laser beam processes its designated regions without interfering with others, preserving both productivity and electrical characteristics
Solution Approach 2:
By organizing the crystallization process into multiple blocks with distinct laser paths, the patent adds a spatial dimension to the processing scheme. This allows parallel or sequential processing that maintains speed while improving reliability through non-overlapping laser irradiation that prevents shot marks
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 enables uniform crystallization of silicon thin films without shot marks, improving the electrical characteristics and process efficiency by selectively crystallizing active regions, thereby enhancing the performance of thin film transistors in display devices.
Implementation Method 1
an amorphous silicon thin film is crystallized by instantaneously irradiating a high energy laser beam onto the amorphous silicon thin film for a time of tens of nsec (nanoseconds)
Implementation Method 2
the amorphous silicon thin film is melted and crystallized in a very short time
Data Source
AI summary
Provided is a method for crystallizing using a laser mask for selectively crystallizing active regions without a laser shot mark, including: providing an array substrate in which N×M active regions are defined; positioning a laser mask having first and second blocks over the substrate, wherein the first and second blocks have first and second mask patterns, respectively, and the second mask pattern is a reverse pattern of the first mask pattern; irradiating a first laser beam onto the active regions through the first block; and irradiating a second laser beam onto the active regions through the second block.