Laser Wafer Thinning Control for Uniform Modification Layers
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Solution Overview
Problem
The existing semiconductor wafer thinning processes are inefficient due to the need for frequent replacement of grinding whetstones and the generation of waste liquids, which complicates the disposal and maintenance, and there is a need to improve throughput in the thinning process.
Innovation Solution
A wafer processing system equipped with a modifying apparatus that uses laser light to form modification layers within the wafer, allowing for dry processing without the need for grinding whetstones and waste liquids, and a controller to optimize the positioning and frequency of laser light application for efficient thinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If grinding whetstone is used for wafer thinning, then wafer thickness can be controlled, but maintenance frequency increases and waste liquid is generated
Solution Approach 1:
The patent replaces the mechanical grinding system with a laser-based processing system. The laser irradiation modifies the wafer material properties without requiring physical contact or grinding whetstones, thereby eliminating maintenance needs and waste liquid generation while maintaining thickness control precision
Solution Approach 2:
The patent changes the processing parameter from mechanical force (grinding) to optical energy (laser irradiation). By controlling laser power, irradiation time, and scanning speed, the wafer thickness is precisely controlled without the drawbacks of mechanical grinding
2Manufacturing precision
If grinding whetstone is used for wafer thinning, then wafer thickness can be controlled, but waste liquid disposal becomes complicated
Solution Approach 1:
The patent replaces mechanical grinding with laser irradiation, which is a non-contact, dry processing method. This substitution eliminates the generation of waste liquid and grinding slurry, removing the disposal complications while maintaining precise wafer thickness control
Solution Approach 2:
The patent converts the potential harm of material removal into a beneficial controlled process. By using laser irradiation, the material is selectively modified and removed only where needed, without generating harmful waste liquid byproducts
3Productivity
If laser light frequency is increased to reduce processing time, then throughput improves, but modification layer precision decreases
Solution Approach 1:
The patent dynamically adjusts laser processing parameters based on real-time conditions. The controller modifies laser power, scanning speed, and irradiation pattern adaptively to maintain precision across varying processing speeds, allowing high throughput without sacrificing modification layer accuracy
Solution Approach 2:
The patent implements a feedback control system that monitors the modification layer formation process and adjusts laser parameters accordingly. This ensures that even at high processing speeds, the precision of modification layers is maintained through continuous optimization based on actual process conditions
4Productivity
If laser moving speed is increased to enhance throughput, then processing efficiency improves, but boundary position accuracy decreases
Solution Approach 1:
The patent replaces mechanical positioning systems with a laser-based optical positioning and measurement system. This allows for high-speed processing while maintaining boundary position accuracy through non-contact optical detection and real-time position feedback
Solution Approach 2:
The patent performs preliminary positioning and boundary determination before the main processing occurs. By pre-establishing accurate boundary positions using optical measurement and planning the laser path in advance, the system achieves high processing speeds without compromising position accuracy during actual material modification
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 approach reduces maintenance frequency, eliminates waste disposal issues, and enhances processing efficiency by shortening the time required for wafer thinning, thereby improving throughput.
Implementation Method 1
a modifying device configured to radiate laser light to an inside of the processing target object held by the holder to form modification layers
Implementation Method 2
radiate laser light to an inside of the processing target object held by the holder to form modification layers along a plane direction thereof
Data Source
AI summary
In forming modification layers by radiating laser light to an inside of a processing target object from a modifying device periodically while rotating the processing target object held by a holder relative to the modifying device by a rotating mechanism and by moving the modifying device relative to the holder in a diametrical direction by a moving mechanism, a boundary position of the laser light in the diametrical direction is calculated, the boundary position being a position where a circumferential distance between the modification layers becomes a required threshold value, and a diametrical distance between the modification layers is reduced in a moving direction of the modifying device from the boundary position and/or a frequency of the laser light is reduced.