Workpiece Dividing via Laser Through Planarized Adhesive Tape
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Solution Overview
Problem
The challenge is to accurately form modified layers in a workpiece, such as a semiconductor wafer, when a laser beam is applied through a supporting tape with a pear-skin surface, as the refractive index difference between the tape and air causes scattering, preventing sufficient focusing and layer formation.
Innovation Solution
A method involving the application of a liquid resin to planarize the pear-skin surface of the supporting tape, followed by curing, allowing the laser beam to be focused at a predetermined depth within the workpiece, thereby forming modified layers along division lines for precise division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a supporting tape with pear-skin surface is attached to the workpiece to facilitate handling and expansion, then ease of operation is improved, but manufacturing precision deteriorates due to laser beam scattering at the uneven surface
Solution Approach 1:
A liquid resin coating is applied as an intermediary layer between the pear-skin surface of the supporting tape and the laser beam. This coating fills the uneven portions of the pear-skin surface, creating a planarized surface that allows the laser beam to pass through without scattering, thereby enabling precise formation of modified layers while maintaining the ease of handling provided by the supporting tape
Solution Approach 2:
The surface topology of the supporting tape is changed from uneven (pear-skin) to planar by applying and curing liquid resin. This parameter change in surface flatness eliminates the scattering effect on the laser beam while preserving the underlying supporting tape's functional properties for handling and expansion
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 ensures accurate formation of modified layers even with a pear-skin surface, enabling reliable division of the workpiece along desired lines, improving processing accuracy and efficiency.
Implementation Method 1
applying a laser beam having a transmission wavelength to the liquid resin, the adhesive tape, and the workpiece from the side of the exposed surface of the adhesive tape to the workpiece in the condition where the focal point of the laser beam is set at a predetermined depth in the workpiece
Implementation Method 2
forming a plurality of modified layers in the workpiece along the division lines
Implementation Method 3
applying a liquid resin to the exposed surface of the adhesive tape and next curing the liquid resin to thereby planarize the exposed surface of the adhesive tape
Data Source
AI summary
In a semiconductor wafer with a supporting tape attached to the back side of the wafer, a coating member having a refractive index close to that of the supporting tape is formed on a pear-skin surface of the supporting tape to thereby planarize the pear-skin surface. Thereafter, a pulsed laser beam is applied from the upper side of the coating member to the semiconductor wafer in the condition where the focal point of the pulsed laser beam is set at a predetermined depth in the semiconductor wafer. Accordingly, the pulsed laser beam can be sufficiently focused inside the semiconductor wafer to thereby well form a modified layer inside the semiconductor wafer.