Sapphire Substrate Laser Division for LED Chip Cracking
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Solution Overview
Problem
The use of sapphire single crystal substrates in semiconductor light-emitting chip production often results in cracking during the division process, which affects the integrity and yield of the chips.
Innovation Solution
A method involving the formation of specific dividing grooves and modified regions on a sapphire substrate using laser irradiation, where the grooves and regions are oriented along distinct crystal planes of the sapphire, allowing for controlled division and minimizing cracking by varying the depth and intensity of laser irradiation and the overlap of these regions with the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sapphire single crystal substrate is used for semiconductor light-emitting chip production, then high thermal stability and chemical inertness are achieved, but cracking occurs in semiconductor light-emitting elements during the division process
Solution Approach 1:
The patent applies preliminary action by forming modified regions in the sapphire substrate before the division process. These modified regions are created through laser irradiation that changes the physical properties of the substrate, creating preferential paths for division that avoid cracking the semiconductor light-emitting elements. The modified regions serve as pre-prepared division paths that guide the cutting process safely through the substrate without transmitting harmful stresses to the mounted elements.
Solution Approach 2:
The patent applies local quality by creating modified regions with different physical properties than the surrounding sapphire substrate. The laser irradiation creates localized zones with altered density, refractive index, and mechanical properties. These locally modified regions provide controlled division paths while the rest of the substrate maintains its original high thermal stability and structural integrity, allowing division without affecting the overall reliability of the substrate material.
2Manufacturing precision
If laser beam is focused on interior of element-group formation substrate to form modified regions, then division control is improved, but complexity of the production process increases
Solution Approach 1:
The patent replaces mechanical division methods with optical field-based modified region formation. Instead of using mechanical sawing or cutting tools that directly contact and potentially damage the semiconductor elements, the invention uses laser irradiation to create modified regions that guide subsequent division. This substitution of mechanical action with optical field processing reduces direct mechanical stress on the elements while maintaining precise division control through the optically created pathways.
3Manufacturing precision
If dividing grooves are formed on semiconductor lamination substrate, then division paths are defined, but risk of cracking semiconductor layer increases
Solution Approach 1:
The patent applies dimensionality change by moving the division path creation from the surface level to the interior depth of the sapphire substrate. Instead of forming dividing grooves on or near the surface where semiconductor elements are mounted, the invention creates modified regions deeper within the substrate interior. This spatial relocation to another dimension (depth) allows definition of division paths that bypass the vulnerable surface region containing the semiconductor elements, thereby reducing cracking risk while maintaining precise path control.
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 effectively suppresses cracking in semiconductor light-emitting elements, improving the production yield and reducing defective chips, while maintaining the structural integrity of the chips.
Implementation Method 1
irradiating the semiconductor lamination substrate, on which the plural dividing grooves are formed, with laser light from a side of the back surface
Implementation Method 2
forming, in the sapphire substrate, plural first modified regions extending toward the first direction and plural second modified regions extending along the front surface of the sapphire substrate
Data Source
AI summary
In producing a semiconductor light-emitting chip whose substrate is composed of a sapphire single crystal, cracking in semiconductor light-emitting elements in the obtained semiconductor light-emitting chip is suppressed. A semiconductor light-emitting chip is obtained by forming, on an element-group formation substrate on a front surface of which semiconductor light-emitting elements are formed, the front surface being composed of a C-plane of a sapphire single crystal, dividing grooves extending toward a first direction along an M-plane of the sapphire single crystal and the front surface of the substrate from a substrate front surface side (step 103), forming first modified regions extending toward the first direction and second modified regions extending along the substrate front surface and toward a second direction different from the first direction in the substrate (step 104 and step 105), and dividing the element-group formation substrate using the first modified regions and the second modified regions (step 106).