Laser Processing Multilayer Substrates via Rear-Side Irradiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser processing methods for cutting substrates with multilayer parts struggle to achieve high precision, particularly when cutting functional devices such as semiconductor operating layers, light-receiving devices, and circuit devices, due to limitations in controlling fractures and preventing damage to low dielectric constant films.
Innovation Solution
A laser processing method that involves attaching a protective member to the front face of the multilayer part, irradiating the substrate with laser light using the rear face as the entrance surface to form a modified region within the substrate, generating a fracture that reaches the front face, and then using an expandable member to cut along the desired line, ensuring high precision and preventing damage to low dielectric constant films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser light is irradiated from the front face to form a modified region, then the modified region can be formed directly, but the multilayer part including low dielectric constant films may be damaged or torn
Solution Approach 1:
The patent applies inversion by irradiating laser light from the rear face of the substrate instead of the front face. This reverses the conventional approach, allowing the modified region to be formed without directly exposing the multilayer part on the front face to high-intensity laser energy, thereby preventing damage to low dielectric constant films while still achieving precise cutting
Solution Approach 2:
The substrate acts as an intermediary medium that transmits laser energy from the rear face to form a modified region. The protective member attached to the front face serves as another intermediary that prevents direct laser interaction with the multilayer part, allowing the cutting process to proceed without damaging sensitive films
2Productivity
If high power laser is used to generate fracture quickly, then productivity increases, but control over fracture propagation and cutting precision deteriorates
Solution Approach 1:
The patent applies preliminary action by first forming a modified region within the substrate before generating the final fracture. This pre-formed modified region serves as a controlled starting point for fracture propagation, ensuring that the fracture follows the desired cutting line with high precision while maintaining efficient cutting speed
Solution Approach 2:
The cutting process is segmented into distinct stages: first forming a modified region along the cutting line, then generating a fracture from this modified region. This segmentation allows each stage to be optimized independently - the modified region formation ensures precision while the subsequent fracture propagation provides efficient material separation
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 enables precise cutting of both the substrate and multilayer parts, including functional devices, with reduced risk of tearing or peeling of low dielectric constant films, achieving high precision and controlled fracture patterns.
Implementation Method 1
The modified region is formed by irradiating the substrate with laser light while locating a converging point therewithin, so as to form multiphoton absorption or light absorption equivalent thereto within the substrate.
Implementation Method 2
cutting the object along the line to cut by expanding the expandable member after attaching the expandable member
Data Source
AI summary
A laser processing method is provided, which, when cutting an object to be processed comprising a substrate and a multilayer part, formed on a front face of the substrate, including a functional device, can 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.