Semiconductor Substrate Laser Cutting via Modified Region Fracture
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Solution Overview
Problem
Conventional laser processing methods for cutting substrates with multilayer parts and semiconductor chips lack precision, particularly when forming modified regions within the substrate to initiate cutting, leading to suboptimal cutting results.
Innovation Solution
A laser processing method that forms a modified region within the substrate by irradiating it with laser light, creating a converging point to generate multiphoton absorption, allowing for precise cutting by forming a fracture that reaches the substrate's front face from the modified region's end part, and using an expandable member to enhance cutting precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a modified region is formed within the substrate by conventional laser processing methods, then cutting can be initiated from the modified region, but the cutting precision of the multilayer part is insufficient
Solution Approach 1:
The patent applies local quality by creating a modified region with specific characteristics (multiphoton absorption zone) at a precise location within the substrate. This modified region serves as a controlled starting point for fracture propagation, ensuring that the cutting process begins with high precision at the intended location while maintaining integrity of the multilayer part.
Solution Approach 2:
The patent employs preliminary action by pre-forming the modified region within the substrate before the actual cutting process. This modified region acts as a pre-prepared starting point that guides subsequent fracture propagation, ensuring accurate cutting initiation and improving overall cutting precision of the multilayer part.
2Manufacturing precision
If the converging point is located within the substrate to form a modified region, then cutting can start from the modified region, but the fracture may not reach the front face with sufficient precision
Solution Approach 1:
The patent applies parameter changes by optimizing the position of the converging point and the characteristics of the modified region to control fracture propagation. By adjusting parameters such as the depth and distribution of the modified region, the fracture is guided to reach the front face with high precision, overcoming the limitation of distance.
3Productivity
If conventional laser processing is used to cut the substrate and multilayer part, then cutting can be performed, but the multilayer part suffers damage or poor cut quality
Solution Approach 1:
The patent introduces the modified region as an intermediary element between the laser processing and the final cut. This modified region acts as a mediator that controls the fracture propagation path, ensuring that the cutting process proceeds cleanly through the multilayer part without causing damage, while maintaining high productivity.
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
Enables high-precision cutting of both substrates and multilayer parts, ensuring accurate separation of semiconductor chips with minimal damage to the front face, even when the substrate thickness ranges from 30 μm to 150 μm.
Implementation Method 1
forms a modified region within the substrate along a line to cut by generating multiphoton absorption or light absorption equivalent thereto within the substrate
Data Source
AI summary
A semiconductor device is provided, which, when cutting a substrate formed with a multilayer part including a plurality of functional devices, makes it possible to cut the multilayer part with a high precision in particular. In a state where a protective tape 22 is attached to the front face 16a of a multilayer part 16, a substrate 4 is irradiated with laser light L while using its rear face 4b as a laser light entrance surface, so as to form a modified region 7 within the substrate 4 along a line to cut, thereby generating a fracture 24 reaching the front face 4a of the substrate 4 from a front-side end part 7a of the modified region 7. Attaching an expandable tape to the rear face 4b of the substrate 4 and expanding it in the state where such a fracture 24 is generated can cut not only the substrate 4 but also the multilayer part 16 on the line to cut, i.e., interlayer insulating films 17a, 17b, with a favorable precision along the line to cut.