Laser-Assisted Wafer Grinding for Thickness Distribution Control
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Solution Overview
Problem
Existing processing methods for device chips, such as grinding and polishing, face challenges in achieving high accuracy due to variability in workpiece thickness and irregularities, leading to inconsistent results.
Innovation Solution
A processing apparatus equipped with a chuck table, a processing unit, a measuring unit, a laser beam applying unit, and a control unit that adjusts the laser beam power based on the workpiece's thickness distribution to control the removal amount during grinding or polishing, ensuring precise processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional grinding or polishing methods are used without real-time thickness control, then the processing speed is maintained, but the manufacturing precision deteriorates due to variability in workpiece thickness and warping
Solution Approach 1:
The system performs preliminary measurement of workpiece thickness distribution using a measuring unit before processing, and pre-calculates the required laser beam power for each region based on the measured thickness variations. This preliminary action enables the subsequent processing to achieve high precision without requiring complex real-time adjustments during the actual grinding or polishing operation.
Solution Approach 2:
The system implements a feedback mechanism where the measuring unit continuously monitors the workpiece thickness distribution, and the control unit adjusts the laser beam power accordingly based on the measured data. This closed-loop feedback system maintains manufacturing precision by compensating for thickness variations and warping in real-time during the processing operation.
2Manufacturing precision
If uniform laser beam power is applied across the entire workpiece, then the device complexity is reduced, but the manufacturing precision deteriorates due to inability to compensate for thickness variations in different regions
Solution Approach 1:
The system applies local quality by varying the laser beam power according to the specific thickness requirements of different regions on the workpiece. The control unit calculates and applies higher power to thicker regions and lower power to thinner regions, ensuring uniform material removal rate across the entire workpiece surface and achieving consistent thickness control in each local area.
Solution Approach 2:
The system changes the laser beam power parameter dynamically across different spatial locations on the workpiece. By adjusting the power parameter based on the measured thickness distribution, the system optimizes the processing effectiveness in each region, enabling precise thickness control without requiring complex mechanical adjustments to the processing tool itself.
3Manufacturing precision
If the laser beam power is increased to process thicker regions, then the removal amount increases for those regions, but the manufacturing precision deteriorates due to excessive removal in already thin regions
Solution Approach 1:
The system applies different laser beam power levels to different regions based on their local thickness characteristics. Thicker regions receive higher power to achieve sufficient material removal, while thinner regions receive lower or no power to prevent excessive removal. This localized power distribution ensures that material is removed only where needed, maintaining target thickness accuracy while minimizing unnecessary material loss.
Solution Approach 2:
The system applies partial action by selectively applying laser beam power only to regions where material removal is needed, rather than uniformly treating the entire workpiece surface. This approach prevents excessive action (over-removal) in already thin regions while ensuring sufficient action in thicker regions, thereby achieving precise thickness control with minimal material waste.
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 enables highly accurate processing of workpieces by controlling the laser beam power to match the workpiece's thickness distribution, resulting in improved precision and consistency in achieving target thickness and flatness.
Implementation Method 1
a laser beam applying unit that has an adjustor for adjusting power of a laser beam applied to the workpiece
Data Source
AI summary
A processing apparatus includes: a chuck table that is configured to be capable of rotation in a state of supporting the workpiece; a processing unit including a spindle to which a processing tool for grinding or polishing is mounted and a drive source that rotates the spindle; a measuring unit that measures distribution of thickness of the workpiece; a laser beam applying unit that has an adjustor for adjusting power of a laser beam applied to the workpiece; and a control unit including a power setting section that sets the power of the laser beam applied to an arbitrary region of the workpiece based on the distribution of the thickness of the workpiece measured by the measuring unit, and an adjustor control section that controls the adjustor of the laser beam applying unit such as to realize the power of the laser beam set by the power setting section.