Wafer Laser Processing Position Correction via Plasma Imaging
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Solution Overview
Problem
The focused point of a laser beam in semiconductor wafer processing cannot be accurately set at a preset processing position due to strain in the optical system, leading to errors in processing location.
Innovation Solution
A wafer processing method using a pulsed laser beam with alignment and imaging techniques to detect and correct the positional relation between the laser processed groove and the preset processing position, incorporating metal patterns for precise kerf checks and real-time correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam processing is performed using a laser processing apparatus, then wafer division can be achieved, but the focused point cannot be set at the preset processing position due to strain in the optical system, resulting in processing position errors
Solution Approach 1:
The patent implements a feedback mechanism where the imaging means captures the actual position of the laser processed groove, compares it with the preset processing position, and feeds back the positional deviation information to the control means. The control means then adjusts the laser processing parameters based on this feedback to correct the position error, forming a closed-loop control system that continuously monitors and corrects processing position deviations.
Solution Approach 2:
The patent replaces direct mechanical positioning measurement with optical field-based measurement. Instead of using mechanical sensors to detect groove position, the system uses imaging means (optical system) to capture images of the laser processed groove and determine its position through image processing, substituting mechanical measurement with optical measurement to achieve higher precision and avoid mechanical interference.
2Measurement precision
If alignment means are used to detect division lines, then processing position can be determined, but strain in the optical system causes the focused point to deviate from the preset position
Solution Approach 1:
The system uses feedback by imaging the actual laser processed groove position and comparing it with the preset position. The positional deviation detected through imaging feedback is used to correct alignment errors, ensuring that subsequent grooves are formed at accurate positions even when initial alignment has deviations due to optical system strain.
Solution Approach 2:
The patent creates an optical copy (image) of the laser processed groove using the imaging means. This optical copy is then processed to determine the actual groove position, allowing virtual measurement and correction without physical contact, thereby preserving the integrity of both the alignment and processing systems.
3Manufacturing precision
If real-time imaging of beam plasma is performed to measure positional relation, then processing accuracy can be improved, but the system complexity increases
Solution Approach 1:
The imaging means serves multiple functions: it images the division lines during alignment, images the beam plasma during processing, and provides positional measurement data. By making the imaging system multi-functional, the patent avoids adding separate dedicated measurement devices, thereby reducing overall system complexity while achieving real-time positional monitoring and measurement capabilities.
Solution Approach 2:
The patent merges the alignment function and the measurement function into a single integrated system. The same imaging means used for detecting division lines during alignment is also used for imaging beam plasma and measuring groove position during processing, combining multiple functions into one device to simplify the overall system architecture.
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 accurate processing of wafers at desired positions by detecting and correcting deviations in laser groove formation, ensuring high precision and avoiding erroneous recognition, thus improving the accuracy of wafer division.
Implementation Method 1
pulsed laser beam applying means to apply a pulsed laser beam from the pulsed laser beam applying means to the wafer
Implementation Method 2
imaging an area including a beam plasma generated by applying the pulsed laser beam from the pulsed laser beam applying means to the wafer
Data Source
AI summary
Disclosed herein is a wafer processing method including a processed position measuring step of imaging an area including a beam plasma generated by applying a pulsed laser beam to a wafer, by using an imaging unit during the formation of a laser processed groove on the wafer, and next measuring the positional relation between the position of the beam plasma and a preset processing position. Accordingly, it is possible to check whether or not the laser processed groove is formed at a desired position, in real time during laser processing. If the position of the laser processed groove is deviated, the processed position can be immediately corrected.