Multibeam Semiconductor Laser Wiring Layout for Spacer Pressure Relief
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Solution Overview
Problem
In multibeam semiconductor laser elements with narrow beam pitches, the multilayered wiring structure connecting electrode pads and laser resonators can lead to reliability issues during the coating process, as the pressure from spacers can concentrate and cause cracks in the insulating layer, resulting in electrical short circuits.
Innovation Solution
The introduction of a thick film pad in the pad region, with a height higher than the multilayered wiring structure, redistributes the pressure during the coating process, reducing the force on the wiring structure and enhancing the reliability of the semiconductor laser element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a narrow beam pitch is adopted to downsize the lens and MEMS mirror, then the beam pitch is reduced, but the electrode pad must be positioned at the chip end requiring multilayered wiring that crosses the laser resonator, causing the multilayered wiring structure to contact spacers during coating and concentrate pressure that may crack the insulating layer
Solution Approach 1:
A thick film pad is introduced as an intermediary structure between the multilayered wiring and the spacer. This thick film pad has a height greater than that of the multilayered wiring structure, allowing it to contact the spacer first and prevent direct contact between the spacer and the multilayered wiring, thereby distributing the pressure and preventing insulating layer cracks
Solution Approach 2:
The solution adds a height dimension by forming a thick film pad that protrudes above the multilayered wiring structure. This vertical dimensionality change creates a stepped structure where the thick film pad serves as a pressure-bearing element, separating the horizontal wiring layout from the vertical pressure application point
2Ease of manufacture
If the multilayered wiring structure is formed to connect the electrode pad and laser resonator, then electrical connection is achieved, but the wiring structure height creates contact with spacers during coating causing pressure concentration
Solution Approach 1:
The thick film pad acts as a mediator that intercepts the pressure from the spacer before it reaches the multilayered wiring structure. By being positioned in the pad region and having greater height, it serves as a protective intermediary that distributes mechanical stress away from the sensitive wiring and insulating layer
Data Source
AI summary
A semiconductor laser element includes a plurality of three or more laser resonators integrated adjacent to each other in the first direction. Each laser resonator has an independent power supply electrode, a second direction which is regarded as a longitudinal direction, and an end face which is coated. A plurality of electrode pads are formed in a pad region adjacent to the laser region in the first direction. Each of the wirings for connection extends in the first direction and is electrically connected the power supply electrode of the corresponding laser resonator and the corresponding electrode pad. The thick film pad is formed on the pad region and is higher than the multilayered wiring structure of the wirings for connection.