Laser Dicing Across Bonded Wafer Interfaces With Less Damage
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Solution Overview
Problem
Conventional laser dicing methods for bonded wafers are prone to thermal damage, debris formation, and uneven stress, leading to reduced production yield and increased fabrication costs due to the need for cooling and mechanical sawing, which are not effective for simultaneous dicing of multiple wafers.
Innovation Solution
A laser dicing system that forms ablation structures within the bonded structure, allowing for simultaneous separation of wafers with uniform cross-sections by adjusting the focal plane of the laser beam to create ablation structures across the bonding interface, eliminating the need for cooling and minimizing debris and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical probes or chemical etchants are used to separate bonded structures, then separation can be achieved, but the structures are damaged or degraded
Solution Approach 1:
The patent replaces mechanical probing methods with optical field-based laser separation. Instead of using physical mechanical probes that contact and potentially damage the bonded structures, the invention uses focused laser energy to selectively break bonds through photonic mechanisms, thereby eliminating mechanical damage while achieving precise separation.
Solution Approach 2:
The patent changes the separation mechanism from mechanical/chemical parameters to optical parameters. By controlling laser wavelength, pulse duration, and intensity, the system achieves bond separation without the damaging effects of mechanical force or chemical etchants, preserving structural integrity while enabling precise separation.
2Reliability
If mechanical probes are used for separation, then bonds can be broken, but cross-contamination occurs and structures are damaged
Solution Approach 1:
The patent replaces mechanical contact-based separation with non-contact optical field-based separation. The laser energy interacts with the bonds through electromagnetic fields without physical contact, eliminating the source of cross-contamination that arises from mechanical probe contact with multiple structures.
3Reliability
If chemical etchants are used to separate structures, then bonds can be broken, but the structures are damaged
Solution Approach 1:
The patent replaces chemical etching processes with optical field-based laser separation. Instead of using chemical reactions that can damage or degrade the structures being separated, the laser method uses controlled photonic energy to break bonds selectively, preserving structural integrity while achieving reliable separation.
Solution Approach 2:
The patent transitions from chemical parameter control to optical parameter control. By adjusting laser wavelength, pulse width, and power, the system achieves bond separation with precision that avoids the damaging side effects of chemical etchants, maintaining both separation reliability and structure integrity.
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
The system achieves more uniform cross-sections, reduces damage and waste, and decreases dicing time by allowing simultaneous separation of bonded wafers with fewer defects and no cooling water requirements.
Implementation Method 1
a laser is shone on the bonded structures to break bonds between the first and second structures
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
System and methods for dicing a bonded structure are provided. A method includes the following operations: determining a scan pattern for forming a series of ablation structures in a bonded structure (502); determining relative positions between the series of ablation structures and a bonding interface of the bonded structure (504); determining at least one of one or more focal planes or a depth of focus of a laser beam based on the relative positions between the series of ablation structures and the bonding interface (506); generating the laser beam (508); and moving the laser beam in the bonded structure according to the scan pattern to form the series of ablation structure in the bonded structure (510).