Laser Beam Overlap Control for Polycrystalline Silicon Defect Removal

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Solution Overview

Problem

Existing laser crystallization processes face challenges in effectively removing streak defects in polycrystalline silicon layers, which affect the reliability of display devices.

Innovation Solution

A laser crystallization apparatus with a laser controller that adjusts the intensity and beam width of laser beams using telescopic lenses and mirrors, allowing for multiple overlapping laser irradiations to enhance energy margin and improve the quality of polycrystalline silicon layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single laser beam is radiated onto the substrate, then the process is simple, but the energy margin is insufficient to remove streak defects

Engineering Contradiction:

Improvequality of polycrystalline silicon layerVSAvoidenergy margin of laser beam

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent combines multiple laser beams (first laser beam from laser irradiation part and second laser beam from laser controller) to irradiate the same region on the substrate. This merging of multiple energy sources increases the total energy margin delivered to the amorphous silicon layer, enabling effective removal of streak defects and improvement of polycrystalline silicon layer quality without requiring excessive intensity from a single beam

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the laser beam intensity is increased to remove streak defects, then the quality improves, but the risk of damage or overheating increases

Engineering Contradiction:

Improvequality of polycrystalline silicon layerVSAvoidoverheating or damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the laser irradiation process into two separate controllable beams: a first laser beam from a laser irradiation part and a second laser beam from a laser controller. Each beam can be independently controlled in intensity and timing, allowing the total energy to be distributed safely across two lower-intensity irradiations rather than one high-intensity irradiation, thus removing streak defects without causing overheating or damage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic or sequential irradiation where the first laser beam and second laser beam are radiated in sequence or with controlled timing. This periodic action allows the substrate to partially cool between irradiations, preventing thermal accumulation and damage while ensuring sufficient total energy delivery to eliminate streak defects through multiple passes

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If the laser beam is radiated only once, then the process is fast, but the energy margin is insufficient

Engineering Contradiction:

Improveenergy marginVSAvoidprocessing speed

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent uses a laser controller to receive and process a first laser beam before radiating it as a second laser beam onto the substrate. This preliminary action allows optimization of the second beam's parameters (intensity, timing, focus) to complement the first beam, ensuring that the combined energy delivery is efficient and effective in removing streak defects without requiring excessive processing time

Inventive Principle:

Principle #10Preliminary action

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 effectively removes streak defects in polycrystalline silicon layers, enhancing the reliability and quality of display devices by increasing the intensity of laser beams and securing energy margins.

Implementation Method 1

the laser controller includes a first lens having a first focal length and a second lens having a second focal length different from the first focal length, and the laser controller radiates a third laser beam

Methodology Applied

Scientific EffectLens focusing: Lens

Implementation Method 2

the laser controller may further include a first mirror and a second mirror which reflect the second laser beam

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

The temperature of an amorphous silicon layer on the substrate is increased by the excimer laser, and then decreased again, and the process is repeated, such that the amorphous silicon is melted and recrystallized

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 4

the amorphous silicon is melted and recrystallized

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 5

the amorphous silicon is melted and recrystallized

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS20260008126A1Laser crystallization apparatus

Publication Date: 2026.01.08 SAMSUNG DISPLAY CO LTD

AI summary

A laser crystallization apparatus includes a laser irradiation part which radiates a first laser beam to a substrate, a laser controller which receives a second laser beam, where the laser controller includes a first lens having a first focal length and a second lens having a second focal length different from the first focal length, and the laser controller radiates a third laser beam, where the second laser beam is the first beam reflected from the substrate, and the third laser beam is the second laser beam passed through the laser controller, where an intensity of the second laser beam is adjusted by the laser controller.