Wafer Division via Laser Grooves and Blade Cutting
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Solution Overview
Problem
The existing wafer dividing method using laser-processed grooves is prone to issues such as sudden cracking due to cutting blade contact, peeling of the functional layer, excessive groove width requiring larger division lines, and the undercut phenomenon caused by laser energy transmission through passivation films, which reduces device density and increases the risk of damage to circuitry.
Innovation Solution
A method involving a protective member to prevent cutting blade contact, forming cut grooves from the backside of the substrate, using dicing tape for support, and performing ablation processing with a laser beam along the division lines to cut the functional layer without contacting the cutting blade, allowing energy to escape through cut grooves and reducing groove width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cutting blade is used to cut along division lines, then the wafer can be divided, but the Low-k film peels off and reaches circuitry causing fatal damage
Solution Approach 1:
The cutting process is divided into two distinct stages: first forming laser-processed grooves to separate the Low-k film, then using a cutting blade to cut the substrate along the pre-formed grooves. This segmentation prevents the blade from directly contacting and peeling the Low-k film while still achieving complete wafer division.
Solution Approach 2:
The laser-processed grooves are formed in advance before the cutting blade operation. These grooves create a separation path that guides the subsequent blade cutting, ensuring the blade follows the division lines without causing Low-k film peeling that would occur with direct blade contact.
2Manufacturing precision
If laser beam irradiation is performed to form grooves, then the Low-k film can be separated, but fused material adheres to the groove side surface causing sudden cracking
Solution Approach 1:
The laser-processed groove acts as an intermediary structure that separates the Low-k film from the substrate. By forming this groove first, the subsequent cutting blade operates in a controlled path that avoids direct contact with the Low-k film, preventing both peeling and sudden cracking while maintaining separation precision.
3Reliability
If the laser-processed groove width is increased to prevent blade contact, then the Low-k film is protected, but the division line width must be enlarged reducing device count
Solution Approach 1:
The cutting process is segmented into laser groove formation followed by blade cutting along the groove. This allows the groove width to be optimized for Low-k film protection while the blade cutting precision ensures accurate division lines, maintaining high device density without compromising film integrity.
4Manufacturing precision
If laser beam irradiation is performed through the passivation film, then the functional layer can be processed, but the laser energy has no escape route causing undercut phenomenon
Solution Approach 1:
The harmful laser energy that would cause undercutting is extracted or removed by forming the laser-processed groove first. This groove provides a pathway that allows subsequent blade cutting to occur precisely along the division line without the laser energy spreading laterally into the functional layer, thereby eliminating the undercut phenomenon.
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 prevents sudden cracking and peeling, allows for narrower division lines increasing device density, and eliminates the undercut phenomenon by ensuring the laser processing does not contact the cutting blade, thereby enhancing the precision and efficiency of wafer division.
Implementation Method 1
irradiating a laser beam along the division lines formed in the functional layer forming the wafer for which the wafer supporting step has been carried out to perform ablation processing for the functional layer and cut the functional layer
Data Source
AI summary
A wafer processing method includes a cut groove forming step of positioning, from a back side of the substrate, a cutting blade to an area corresponding to a division line to form cut grooves in such a manner that the cutting blade does not reach a functional layer and part of a substrate is left, and a functional layer cutting step of performing irradiation with a laser beam along the division lines formed in the functional layer forming a wafer to perform ablation processing for the functional layer and cut the functional layer. In the cut groove forming step, the cut grooves are formed along the division lines in such a manner that an uncut part is left in a peripheral area of the wafer.