Laser Power Adjustment for Wafer Thickness Control
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Solution Overview
Problem
Existing methods for processing wafers, such as chemical mechanical polishing, struggle to achieve high accuracy in achieving target thickness and flatness, especially when there are variations in thickness or irregularities like warpage, recesses, and protrusions.
Innovation Solution
A processing method involving the use of a gas or liquid containing active species, where the workpiece is measured for thickness distribution and irradiated with a laser beam of adjustable power to control the removal amount, with continuous remeasurement and power readjustment to ensure precise processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing is used to process wafers, then the thickness can be adjusted and flatness enhanced, but high accuracy in achieving target thickness and flatness cannot be achieved when there are variations in thickness or irregularities like warpage, recesses, and protrusions
Solution Approach 1:
The patent applies local quality by adjusting laser beam power based on local thickness variations. The thickness distribution is measured first, then the laser beam power is selectively adjusted for different regions - higher power for thick regions, lower power for thin regions - enabling precise thickness control that adapts to local conditions rather than applying uniform processing
Solution Approach 2:
The patent changes the laser beam power parameter based on measured thickness distribution. By dynamically adjusting the power parameter according to actual thickness variations, the processing achieves high accuracy for wafers with warpage, recesses, and protrusions, overcoming the limitation of fixed-parameter polishing methods
2Manufacturing precision
If fixed power laser beam irradiation is used, then the processing is simple, but the removal amount cannot be precisely controlled for regions with different thickness
Solution Approach 1:
The patent implements feedback control by measuring the thickness distribution before processing, using this measurement to adjust the laser beam power, performing processing, and potentially remeasuring to verify results. This closed-loop feedback system enables precise removal amount control despite the added complexity of measurement and adjustment systems
Solution Approach 2:
The patent performs preliminary measurement of thickness distribution before laser processing. This preliminary action provides the necessary information to pre-adjust the laser power settings, ensuring that the subsequent processing achieves the desired precision without requiring complex real-time adjustments during processing
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 method allows for high-accuracy processing of wafers by controlling the removal amount based on thickness distribution, effectively addressing variations and irregularities to achieve the target shape.
Implementation Method 1
a laser beam irradiation step of irradiating the workpiece in the gas or liquid with a laser beam of which the power is adjusted based on the distribution of the thickness measured in the measurement step
Implementation Method 2
a removal amount by which a region irradiated with the laser beam in the workpiece is removed by the active species
Data Source
AI summary
A processing method of a workpiece used when the workpiece is processed is provided. The processing method of a workpiece includes a disposing step of disposing the workpiece in a gas containing a substance that generates an active species that reacts with the workpiece, a measurement step of measuring the distribution of the thickness of the workpiece disposed in the gas, and a laser beam irradiation step of irradiating the workpiece in the gas with a laser beam of which the power is adjusted based on the distribution of the thickness measured in the measurement step. In the laser beam irradiation step, the removal amount by which a region irradiated with the laser beam in the workpiece is removed by the active species is controlled by irradiating the workpiece with the laser beam of which the power is adjusted.