Laser Groove Width Control via Strobe Imaging Feedback
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Solution Overview
Problem
The width of laser-processed grooves in semiconductor wafers becomes inconsistent due to changes in laser beam output power or optical system distortion, leading to suboptimal processing.
Innovation Solution
A laser processing apparatus equipped with a control system that uses strobe light and imaging means to monitor the width of laser-processed grooves in real-time, adjusting the position of the laser beam and suspending processing if deviations exceed acceptable limits, ensuring consistent groove width and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam output power changes or optical system distortion occurs, then laser processing can be performed, but the width of laser-processed groove becomes inconsistent leading to processing quality degradation
Solution Approach 1:
The patent implements a feedback mechanism where the imaging means captures images of the laser-processed groove, the control means calculates the groove width from these images, and this information is fed back to adjust the laser beam output power or optical system parameters to maintain consistent groove width despite power fluctuations or distortion
Solution Approach 2:
The system performs preliminary measurement of the groove width immediately after laser processing using the imaging means, before the workpiece moves to the next processing stage. This allows real-time detection and correction of width variations, ensuring consistent quality
2Manufacturing precision
If real-time monitoring of groove width is implemented, then processing quality can be maintained, but device complexity increases due to additional imaging and control components
Solution Approach 1:
The imaging means serves multiple functions: it captures the groove morphology for width measurement, verifies processing quality, and provides data for feedback control. This multi-functionality reduces the need for separate dedicated measurement devices, thereby limiting the increase in system complexity
Solution Approach 2:
The control means automatically calculates groove width from images captured by the imaging means and performs real-time adjustments without requiring external measurement equipment or manual intervention, making the monitoring system self-sufficient and minimizing additional complexity
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 solution allows for real-time detection and correction of groove width and alignment issues, maintaining desired processing quality by preventing abnormal processing caused by changes in laser beam output or optical distortion.
Implementation Method 1
a dichroic mirror that is disposed between the pulse laser beam oscillating means and the condenser and reflects the pulse laser beam oscillated from the pulse laser beam oscillating means to lead the pulse laser beam to the condenser. The dichroic mirror allows transmission of light having a wavelength other than the wavelength of the pulse laser beam through the dichroic mirror
Implementation Method 2
a beam splitter that is disposed between the strobe light irradiating means and the dichroic mirror and splits light from the workpiece held by the chuck table
Implementation Method 3
a condenser that condenses the pulse laser beam oscillated from the pulse laser beam oscillating means and emits the pulse laser beam to the workpiece held by the chuck table
Data Source
AI summary
A laser beam irradiation unit of laser processing apparatus includes a pulse laser beam oscillating unit, a condenser that condenses a pulse laser beam and emits the beam to a workpiece held by a chuck table, a dichroic mirror disposed between the pulse laser beam oscillating unit and the condenser, a strobe light irradiation unit that emits light to a path on which the dichroic mirror and the condenser are disposed, a beam splitter disposed between the strobe light irradiation unit and the dichroic mirror, and an imaging unit disposed on the path of light split by the beam splitter. A controller actuates the strobe light irradiation unit and the imaging unit according to the timing of the pulse laser beam, and detects the width of a laser-processed groove immediately after emission of the pulse laser beam on the basis of an image signal from the imaging unit.