Laser Division of Crystalline Substrates for Shaped Chips
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Solution Overview
Problem
Crystalline substrates, such as silicon carbide, tend to crack when attempting to divide them into optionally shaped chips due to their crystal orientation, making it difficult to efficiently and reliably manufacture such chips using existing methods.
Innovation Solution
A method involving establishing a projected dicing line and division assisting lines on the substrate, followed by applying a laser beam to form division initiating points that are tangential to the chip contour and extend across all sides of the crystalline structure, allowing for precise and crack-reducing division of the substrate into optionally shaped chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dividing tool is used to divide crystalline substrates into optionally shaped chips, then the division process becomes automated and efficient, but the substrates are highly likely to crack along their crystal orientation
Solution Approach 1:
The patent applies preliminary action by forming modified layers at predetermined positions within the substrate before the division process. These modified layers are created by irradiating the substrate with a laser beam along the crystal orientation, positioning the focused spot inside the substrate to form regions with different physical properties that serve as controlled division paths, preventing cracks during subsequent dividing operations
Solution Approach 2:
The patent changes physical parameters by transforming the substrate material properties at specific locations through laser irradiation. The focused laser beam creates modified layers with altered density, refractive index, and mechanical properties, converting the substrate from a uniform crystalline structure to one with predetermined weak planes that guide crack propagation along desired paths rather than random crystal orientations
2Reliability
If manual division is performed to avoid cracks in crystalline substrates, then crack occurrence is reduced, but the division process becomes inefficient and requires skilled workers
Solution Approach 1:
The patent replaces the mechanical division system with an optical system. Instead of using mechanical dividing tools that directly contact and split the substrate, the invention uses laser beam irradiation to create modified layers that serve as division guides. This substitution eliminates the need for manual mechanical division while maintaining crack-free separation by following the predetermined modified layer paths
Solution Approach 2:
The patent introduces modified layers as an intermediary between the laser processing and the final division. These modified layers act as mediators that guide the division process, allowing automated mechanical division to proceed along predetermined safe paths without causing random cracks, thus enabling both automation and reliability
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 the reliable and efficient production of optionally shaped chips from crystalline substrates by minimizing the occurrence of cracks during the division process, effectively addressing the challenge of working with crystalline materials.
Implementation Method 1
applying a laser beam having a wavelength transmittable through the substrate to the substrate along the contour of the chip and the division assisting line while positioning a focused spot of the laser beam in the substrate at a predetermined position spaced from an upper surface of the substrate
Data Source
AI summary
A method of manufacturing an optionally shaped chip from a substrate having a crystalline structure includes establishing a projected dicing line on the substrate representing a contour of a chip to be fabricated from the substrate, and establishing a straight division assisting line contacting the contour of the chip for assisting in dividing the substrate. A division initiating point is formed after the projected dicing line is established and a laser beam is applied along the contour of the chip and the division assisting line while positioning a focused spot of the laser beam in the substrate at a predetermined position spaced from an upper surface of the substrate, thereby forming division initiating points in the substrate. The substrate is divided by applying external forces to the substrate in which the division initiating points have been formed, to divide the substrate along the division initiating points.