Photosensitive Sheet Detection for Laser Beam Leak Light in Semiconductor Wafer Processing
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Solution Overview
Problem
The existing methods for processing semiconductor wafers using laser beams often result in asymmetric intensity distribution and leak light that can interfere with chip division, making it difficult and costly to evaluate and correct the state of leak light, which affects device quality.
Innovation Solution
A detection method involving a photosensitive sheet positioned between the workpiece and the laser beam's second face, allowing for direct observation of leak light by irradiating the workpiece with a laser beam and confirming the state through the photosensitive reaction, enabling efficient suppression of leak light and adjustment of the optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam with asymmetric intensity distribution is used to process a workpiece, then the processing can be performed, but the modified layer becomes less liable to break and the leak light expands beyond the scheduled division line
Solution Approach 1:
The patent applies preliminary action by positioning a photosensitive sheet on the workpiece before laser beam irradiation. This allows the asymmetric intensity distribution and leak light to be detected in advance through photosensitive reactions, enabling correction of optical system settings before actual processing to ensure accurate division lines
Solution Approach 2:
The photosensitive sheet serves as an intermediary between the laser beam and the workpiece. It captures the leak light and asymmetric intensity distribution through photosensitive reactions, making the invisible laser effects visible and measurable, thereby enabling detection and correction of optical system issues
2Reliability
If conventional methods are used to evaluate leak light influence, then device quality can be assessed, but it requires a very great number of man-hours for electric characteristic evaluation
Solution Approach 1:
The patent replaces the complex electrical characteristic evaluation system with a simple optical detection system using a photosensitive sheet. Instead of performing time-consuming electrical tests on each device chip, the photosensitive sheet provides immediate visual feedback on leak light distribution, dramatically reducing evaluation time while maintaining reliability
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 easy and cost-effective confirmation of leak light, facilitating the selection of optimal processing conditions and adjustment of the optical system, thereby improving the quality and efficiency of semiconductor wafer processing.
Implementation Method 1
a photosensitive sheet positioning step of holding the workpiece on a holding face of a chuck table with a photosensitive sheet, which has a photosensitive layer, interposed therebetween such that the photosensitive layer is opposed to the second face of the workpiece
Data Source
AI summary
A method of detecting a transmission laser beam is disclosed. A laser beam of a wavelength having a transparency to a plate-shaped workpiece having a first face and a second face is irradiated upon the workpiece from the first face side with a focal point of the laser beam positioned in the inside of the workpiece. The laser beam is detected after it has passed through the workpiece to the second face side. A photosensitive sheet is positioned to hold the workpiece on a holding face of a chuck table. A photosensitive layer between the sheet and the workpiece is opposed to the second face of the workpiece. The laser beam is irradiated from the first face side of the workpiece, and the state of the transmission laser beam from a photosensitive reaction region formed in the photosensitive layer of the photosensitive sheet is confirmed.