Three-Stage Laser Waveform for Internal Wafer Processing Control
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Solution Overview
Problem
Existing laser processing methods using chevron-shaped pulse waveforms generate excessive energy that hinders the formation of laser processing regions, causes thermal damage to wafer surfaces, and shortens the lifespan of the laser engine, without adequately addressing the different energy requirements for void and laser processing region formation.
Innovation Solution
A laser processing method utilizing a pulse waveform with a first stage rising to a maximum power, a second stage falling to a reference power, and a third stage maintaining a fluctuating power within a predetermined range, optimizing energy distribution to form laser processing regions efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chevron-shaped pulse waveform is used for internal focusing processing, then laser processing region can be formed inside the wafer, but excessive energy is generated causing thermal damage and shortening laser engine lifespan
Solution Approach 1:
The patent changes the pulse waveform parameters from a conventional chevron shape to a three-stage waveform with specific characteristics: first stage with power rising to maximum at time t0 (1%-20% of pulse width), second stage with power falling to reference value (30%-60% of maximum) at time t1 (3%-40% of pulse width), and third stage with power maintained within predetermined fluctuation range. This parameter optimization reduces excessive energy generation while maintaining laser processing region formation capability.
2Manufacturing precision
If higher power pulsed laser light is used to ensure processing performance, then laser processing region formation is improved, but service life of laser engine is shortened
Solution Approach 1:
The patent optimizes pulse waveform parameters to achieve efficient energy utilization. The three-stage waveform with controlled power distribution (rising to maximum, falling to reference value within 30%-60% range, and maintaining with predetermined fluctuation) reduces the total energy required for processing, thereby extending laser engine service life while maintaining processing performance.
3Force
If conventional pulse waveform is used, then dividing force is increased, but excessive energy hinders laser processing region formation and causes thermal damage
Solution Approach 1:
The patent modifies the pulse waveform parameters to create a three-stage structure that optimizes energy distribution. The first stage builds power to maximum at t0 (1%-20% of pulse width), the second stage reduces power to reference value at t1 (3%-40% of pulse width), and the third stage maintains power within predetermined fluctuation range. This ensures sufficient dividing force while preventing excessive energy that would hinder processing region formation.
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
Enables low-energy internal focusing processing while maintaining processing performance, reducing thermal damage and extending the laser engine's lifespan.
Implementation Method 1
irradiating the workpiece with pulsed laser light with a focal point aligned inside the workpiece
Implementation Method 2
internal focusing processing in which pulsed laser light is irradiated from a laser engine along the street while a focal position of an objective lens of the laser engine is aligned with the inside of the wafer
Data Source
AI summary
In this laser processing method, a pulse waveform F of pulsed laser light L that forms a laser processing region P inside a workpiece (wafer W) includes a first stage waveform ST1 in which power of the pulsed laser light L rises to a maximum value (peak power Pmax) at time to, a second stage waveform ST2 in which the power falls to a reference value (base power Pb) at time t1, and a third stage waveform ST3 in which the power is maintained within a predetermined fluctuation range without falling below the reference value, in which the reference value is within a range of 30% to 60% of the maximum value, the time t0 is within a range of 1% to 20% of the pulse width te, the time t1 is within a range of 3% to 40% of the pulse width te, and a time tp corresponding to half the maximum value is within a range of 2% to 40% of the pulse width te.