Pulsed Laser Substrate Separation for Device Layer Protection
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Solution Overview
Problem
Conventional methods for separating substrates in semiconductor manufacturing, such as the laser lift-off process, face challenges in efficiently separating a second substrate from a first substrate due to the limitations in peak power control of the laser beam, leading to decreased throughput and potential damage to device layers.
Innovation Solution
A substrate processing method involving the formation of a separation modification layer by radiating a CO2 laser in a pulse shape to accumulate stress in a laser absorption layer, allowing for controlled separation of the second substrate from the first substrate without damaging the device layer, by managing the peak power and frequency of the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser beam frequency is reduced to control peak power for substrate separation, then the risk of device layer damage is reduced, but the throughput decreases
Solution Approach 1:
The patent applies periodic pulsed laser irradiation instead of continuous laser beam. By controlling the pulse width, frequency, and duty cycle, the system accumulates stress in the absorption layer during pulses while allowing stress release between pulses, enabling effective separation without requiring reduced peak power that would slow down the process
Solution Approach 2:
The patent changes the temporal parameters of laser irradiation from continuous to pulsed mode. By adjusting pulse width (e.g., 1-100 ns), repetition frequency (e.g., 1-100 kHz), and duty cycle, the system achieves both high peak power for rapid separation and controlled average power to prevent device layer damage, resolving the throughput-reliability contradiction
2Productivity
If high peak power laser beam is used for rapid substrate separation, then the throughput is improved, but the device layer may be damaged
Solution Approach 1:
The pulsed laser irradiation allows high peak power to be delivered in short bursts for rapid stress accumulation and separation, while the intervals between pulses allow heat dissipation and stress release, preventing cumulative damage to the device layer. This periodic action enables both high throughput and device layer protection
Solution Approach 2:
The pulsed irradiation scheme inherently provides cushioning by introducing rest periods between high-power pulses. During these intervals, the absorption layer can release accumulated stress and dissipate heat, preparing the system for the next pulse without causing damage, thus cushioning against potential device layer damage while maintaining high peak power capability
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 effective separation of substrates with improved throughput and reduced risk of device layer damage, as the stress accumulation in the separation modification layer allows for controlled release, facilitating efficient substrate separation without the need for reducing laser beam frequency.
Implementation Method 1
A laser absorption layer is formed on the second substrate... radiating a laser beam to the laser absorption layer in a pulse shape to accumulate a stress in the laser absorption layer
Implementation Method 2
forming a separation modification layer by radiating a laser beam to the laser absorption layer in a pulse shape to accumulate a stress in the laser absorption layer
Data Source
AI summary
A processing method of a combined substrate in which a first substrate and a second substrate are bonded to each other is provided. A laser absorption layer is formed on the second substrate. The substrate processing method includes forming a separation modification layer by radiating a laser beam to the laser absorption layer in a pulse shape to accumulate a stress in the laser absorption layer; and separating the second substrate by releasing the accumulated stress in a chain manner.