LED Chiplet Dicing Groove Structure to Prevent Crack Extension
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Solution Overview
Problem
The existing LED chiplet dicing process using laser stealth dicing results in cracks and edge/corner chipping due to the brittleness of the PV protective layer, which can extend into the epitaxial structure, affecting the performance and reliability of the LED chiplets.
Innovation Solution
A patterned structure with a groove is introduced in the intersecting areas of the dicing channels of LED chiplets, which isolates the repeated contact points of the dicing blade from the epitaxial structure, preventing cracks from extending into the epitaxial layer and reducing the risk of edge and corner chipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser stealth dicing is used to split LED chiplets, then the dicing process can be completed, but cracks and edge/corner chipping occur due to repeated contact between the dicing blade and the brittle PV protective layer
Solution Approach 1:
The patent introduces a patterned structure (groove or hole array) in the PV protective layer at the intersecting area of dicing channels. This segmentation isolates the repeated contact points of the dicing blade from the epitaxial structure, preventing crack propagation into the chiplet. The patterned structure divides the continuous protective layer into separated regions, allowing the dicing blade to contact only the patterned features rather than the underlying epitaxial layer.
Solution Approach 2:
The patterned structure in the PV protective layer acts as an intermediary between the dicing blade and the epitaxial structure. By placing grooves or hole arrays at the intersecting areas, the patent creates a buffer zone that absorbs the mechanical stress and repeated contact of the dicing blade, preventing direct transmission of stress to the brittle epitaxial layer and thus avoiding crack formation and edge/corner chipping.
2Ease of manufacture
If the dicing blade contacts the PV protective layer twice in the intersecting area of dicing channels, then the chiplets can be split, but the repeated contact causes cracks to extend into the epitaxial structure
Solution Approach 1:
The patent applies preliminary action by pre-forming a patterned structure (groove or hole array) in the PV protective layer at the intersecting areas of dicing channels before the dicing process. This pre-prepared patterned structure guides the dicing blade contact points and prevents direct contact with the epitaxial structure, thereby preventing crack extension while maintaining the chiplet splitting function.
Solution Approach 2:
The patent applies local quality by modifying only the specific intersecting areas of the PV protective layer where dicing channels cross, rather than the entire protective layer. The patterned structure (grooves or hole arrays) is localized to these critical intersecting regions, providing crack prevention exactly where the repeated blade contact occurs, while leaving the rest of the protective layer intact to maintain its overall protective function.
3Strength
If the PV protective layer is brittle, then it provides structural integrity, but it is prone to cracking under repeated dicing blade contact
Solution Approach 1:
The patent applies parameter changes by modifying the physical structure of the PV protective layer at the intersecting areas through patterned grooves or hole arrays. This structural parameter change creates stress relief zones that reduce the susceptibility to cracking under repeated dicing blade contact, while the bulk of the PV protective layer maintains its structural integrity and protective function.
Data Source
AI summary
A light-emitting diode includes: a substrate, an epitaxial layer and a protective layer; the epitaxial layer is disposed on the substrate and includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially in that order; the protective layer covers the epitaxial layer; the epitaxial layer is divided into chiplets, each chiplet includes transverse and longitudinal sidewalls intersecting in transverse and longitudinal directions, dicing channels are defined between adjacent chiplets, the dicing channels include transverse and longitudinal dicing channels extending respectively in the transverse and longitudinal directions, the protective layer covers the dicing channels and chiplet sidewalls, a patterned structure is disposed on the protective layer in an intersecting area of the transverse and the longitudinal dicing channels, and includes a groove extending toward the substrate. The light-emitting diode effectively prevents the crack extension, avoids edge and corner chipping during dicing, thus ensuring element quality.