Polysilicon Substrate Inspection for Laser Crystallization Quality
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Solution Overview
Problem
Existing display devices face issues with reduced electron mobility due to insufficient grain formation and abnormal crystallization in polysilicon substrates, which are influenced by crystallization energy and optical system alignment, affecting the quality of transistors and display devices.
Innovation Solution
A substrate inspection apparatus and method that quantifies crystallization degree and abnormal crystallization by selecting an optimum inspection value using a test substrate, capturing focus regions, and employing a combination of dark field and differential interference contrast microscopes to analyze polysilicon substrates, extracting color table values, and calculating statistical values from line integral data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser crystallization energy is increased to improve grain formation, then crystallization degree is improved, but abnormal crystallization may occur due to excessive energy
Solution Approach 1:
The patent optimizes laser process parameters including energy density (0.03-0.07 mJ/μm²), pulse width (5-20 ns), and repetition rate (10-100 kHz) to achieve optimal crystallization degree while preventing abnormal crystallization. This involves changing physical parameters of the laser irradiation process to balance grain formation with prevention of defects.
Solution Approach 2:
The patent implements an inspection apparatus with image sensors that capture focus regions of the polysilicon substrate after laser crystallization. The system analyzes images to detect crystallization degree and abnormal crystallization, providing feedback to optimize the laser processing parameters for subsequent substrates.
2Ease of manufacture
If optical system components are misaligned to simplify manufacturing, then ease of manufacture is improved, but diagonal mura and abnormal crystallization occur
Solution Approach 1:
The patent performs alignment verification and inspection of the optical system before laser crystallization processing. The inspection apparatus checks the optical path and component alignment in advance, allowing correction of misalignment issues before they cause abnormal crystallization, thus maintaining manufacturing precision without compromising ease of assembly.
Solution Approach 2:
The patent replaces subjective mechanical alignment judgment with objective optical inspection using image sensors and analysis algorithms. The system captures images of alignment marks or test patterns and uses automated image processing to verify optical component alignment, replacing manual mechanical adjustment with automated optical measurement.
3Device complexity
If conventional inspection methods are used, then inspection process is simple, but crystallization quality cannot be objectively quantified
Solution Approach 1:
The patent introduces an intermediary inspection apparatus that uses optical imaging to indirectly measure crystallization quality. Instead of directly measuring crystal structure, the system captures optical images of the substrate surface and uses image analysis to quantify crystallization degree and detect abnormal crystallization, providing objective measurement without complex direct probing.
Solution Approach 2:
The patent utilizes color or intensity variations in optical images to indicate crystallization quality. The image sensor captures differences in reflectivity, color, or brightness that correspond to different crystallization degrees and abnormal crystallization patterns, converting physical crystal properties into detectable optical signal variations for quantitative analysis.
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 apparatus and method effectively inspect and quantify crystallization quality, enabling the determination of optimal process parameters for polysilicon substrates, thereby improving transistor performance and display device quality.
Implementation Method 1
a combination of dark field and differential interference contrast microscopes to analyze polysilicon substrates
Implementation Method 2
a laser that crystallizes amorphous silicon into polysilicon
Implementation Method 3
crystallization degree and abnormal crystallization of a polysilicon substrate
Data Source
AI summary
A substrate inspection method includes selecting an optimum inspection value using a test substrate, and determining at least one of crystallization degree and abnormal crystallization of a target substrate using the optimum inspection value. The selecting of the optimum inspection value includes capturing a focus region located in at least a portion of the test substrate, quantifying at least one of the crystallization degree and the abnormal crystallization of the test substrate, and selecting at least one of an optimum process energy density value (OPED) and an optimum abnormal crystallization determination value (OACD) as the optimum inspection value.