Broad Area Semiconductor Laser Chip Grooves to Stop Cleavage Cracks
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Solution Overview
Problem
Broad area semiconductor laser chips experience failures when driven for long durations due to cracking during wafer cleavage, which is exacerbated by the formation of scribing scratches.
Innovation Solution
The chip design includes grooves or stepped regions along the side surfaces, with a minimum spacing of 25 µm from the current injection stripe, to prevent cracking and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If scribing scratch is formed on wafer to form trigger in cleavage, then cleavage can be initiated, but cracking occurs in crystal from starting point of cleavage
Solution Approach 1:
The patent introduces grooves as intermediary structures that mediate between the scribing scratch (cleavage trigger) and the active layer. These grooves act as stress relief channels that intercept cracks before they reach the active layer, thus allowing cleavage to proceed while preventing crack propagation to the functional region.
Solution Approach 2:
The patent segments the wafer structure by introducing grooves that divide the crystal lattice continuity. These grooves create discrete regions that allow controlled separation during cleavage while maintaining structural integrity in the active layer region, effectively segmenting the stress propagation path.
2Reliability
If spacing between grooves and side surfaces is increased to prevent crack propagation, then crack influence is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by establishing the groove spacing parameter (≥25 μm from side surfaces) during the manufacturing process design phase. This predetermined spacing creates a built-in safety margin that accommodates normal manufacturing variations without compromising the crack prevention function, thereby reducing the actual precision requirements during fabrication.
Data Source
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AI summary
Provided is a semiconductor laser chip in which a failure is less likely to occur even when a drive time is long. A broad area type semiconductor laser chip (chip 10) includes a substrate (11), an active layer (13), and a current injection stripe which injects a current into the active layer (13). A pair of side surfaces of the chip include respective rough surfaces (1142, 1162), which serve as starting points of cleavage, and respective cleavage surfaces (1141, 1161), grooves (G1, G2) penetrating the active layer (13) are each formed in a region between a corresponding one of the rough surfaces (1142, 1162) and the current injection stripe, and spacing between each of the grooves (G1, G2) and the corresponding one of the side surfaces is not less than 25 pm.