Laser Processing Apparatus for Sapphire Substrate Peeling
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Solution Overview
Problem
The existing methods face difficulties in reliably breaking the thin gallium nitride buffer layer in optical device wafers using a laser beam, as it is challenging to distinguish and target this layer without damaging the underlying substrate.
Innovation Solution
A laser processing apparatus equipped with plasma detecting means, including a dichroic mirror, band-pass filter, and photodetector, is used to detect the light intensity of plasma generated by applying a pulsed laser beam to the buffer layer, allowing for precise power adjustment to break only the buffer layer while maintaining the substrate integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser beam is applied to the buffer layer to break it, then the epitaxy substrate can be peeled off, but it is difficult to reliably break only the buffer layer without damaging the substrate
Solution Approach 1:
The patent employs plasma light detection as a feedback mechanism to monitor the laser processing of the buffer layer in real-time. The plasma detecting means measures the intensity of plasma light generated during laser irradiation, providing feedback information about the buffer layer breakdown state. This allows dynamic adjustment of laser parameters to achieve reliable selective breaking of the buffer layer without damaging the substrate.
Solution Approach 2:
The patent utilizes the characteristic plasma light emission (color change) that occurs when the buffer layer breaks down under laser irradiation. By detecting the intensity and characteristics of this plasma light, the system can identify the precise moment of buffer layer breakdown, enabling controlled and reliable separation without excessive energy input that could damage the substrate.
2Reliability
If the laser power is increased to ensure buffer layer breaking, then the buffer layer can be reliably broken, but the substrate may be damaged
Solution Approach 1:
The plasma detecting means provides real-time feedback on the buffer layer breakdown status, allowing the laser power to be precisely controlled and adjusted during the process. This feedback mechanism prevents excessive laser power application that could damage the substrate while ensuring sufficient power to break the buffer layer reliably.
Solution Approach 2:
The patent implements dynamic control of laser parameters based on real-time plasma light detection. The laser processing conditions are adjusted dynamically during the process rather than using fixed parameters, enabling the system to adapt to variations in material properties and achieve reliable buffer layer breaking at optimal power levels without substrate damage.
3Manufacturing precision
If the laser beam is applied from the back side of the epitaxy substrate, then the buffer layer can be targeted, but precise power control is difficult without plasma detection
Solution Approach 1:
The plasma detecting means provides real-time feedback on the buffer layer breakdown status, transforming the difficult power control problem into a straightforward feedback-controlled process. The system automatically adjusts laser power based on plasma light intensity, making precise buffer layer breaking achievable without requiring complex manual power adjustment procedures.
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 enables reliable peeling of the sapphire substrate from the optical device layer by accurately controlling the laser power based on plasma light intensity detection, ensuring efficient transfer of the optical device layer to a transfer substrate without damaging the epitaxy substrate.
Implementation Method 1
applying a pulsed laser beam to the optical device wafer held on the chuck table to break the buffer layer
Implementation Method 2
plasma detecting means for detecting the light intensity of plasma light produced in the buffer layer by the application of the pulsed laser beam
Implementation Method 3
the plasma detecting means includes a dichroic mirror for transmitting the pulsed laser beam applied from the laser beam applying means and reflecting the plasma light produced in the buffer layer
Implementation Method 4
a band-pass filter for passing the predetermined wavelength region of the plasma light generated from the substance forming the buffer layer
Implementation Method 5
a photodetector for detecting the light intensity of the plasma light passed through the band-pass filter
Data Source
AI summary
A laser processing apparatus removes a sapphire substrate from an optical device wafer configured by forming an optical device layer on the front side of the sapphire substrate through a buffer layer. A chuck table holds the optical device wafer. A pulsed laser beam is applied to the optical device wafer to break the buffer layer, and the light intensity of plasma light produced in the buffer layer by the application of the pulsed laser beam is detected and displayed. The light intensity of a predetermined wavelength region of the plasma light generated from a substance forming the buffer layer is detected.