Optical Semiconductor Electrode Pad Stepped Structure
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Solution Overview
Problem
In optical semiconductor devices, insufficient contact between the bar and spacer leads to gaps and adhesion issues with insulating films, affecting wire bonding reliability and complexity in manufacturing due to the need for trench structures in electrode pad portions.
Innovation Solution
The optical semiconductor device features a mesa structure with an electrode pad portion and peripheral portion that includes rising surfaces, allowing for improved contact and preventing insulating film adhesion, along with a recess and resin coating to enhance wire bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact between the bar and the spacer is insufficient, then gaps are generated between the bar and the spacer, but the insulating film material wraps around and adheres to the electrode pad portion surface, lowering wire bonding adhesion density
Solution Approach 1:
The electrode pad portion is designed with a stepped structure having different height levels. The first region (pad surface) is at a higher level while the second region (peripheral area) is at a lower level. This dimensional change in height prevents the insulating film material from reaching and adhering to the wire bonding surface, while maintaining proper contact between the bar and spacer at the lower level.
Solution Approach 2:
The electrode pad portion is segmented into distinct regions: a first region for wire bonding and a second region at the periphery. This segmentation allows different functional requirements to be met in different areas - the first region maintains clean surface for wire bonding while the second region provides contact surface for the bar and spacer, preventing material adhesion to the critical bonding area.
2Reliability
If a trench structure is formed in the electrode pad portion to prevent material adhesion, then wire bonding reliability is improved, but the manufacturing process becomes complicated
Solution Approach 1:
Instead of forming complex trench structures, the invention changes the height parameter of the electrode pad portion to create a stepped structure. This parameter change (creating different height levels) achieves the same protective function of preventing material adhesion to the wire bonding surface, but through a simpler manufacturing process that doesn't require complex trench formation.
3Reliability
If the lower surface of the electrode pad portion is made higher than the upper surface of the mesa structure, then wire bonding adhesion is improved, but the risk of insulating film material wrapping around increases
Solution Approach 1:
The invention uses dimensional change by creating a stepped structure with different height levels in the horizontal plane. The electrode pad portion has a first region at a higher level for wire bonding and a second region at a lower level at the periphery. This resolves the contradiction by preventing material wrapping to the high region while maintaining proper contact at the low region.
Data Source
AI summary
Provided is an optical semiconductor device including a semiconductor substrate; a first semiconductor multilayer that is stacked on a first surface side of the semiconductor substrate, has a mesa structure extending along a light emitting direction, and emits light from an exit end surface; an electrode pad portion for wire bonding which is electrically connected to the upper surface of the mesa structure of the first semiconductor multilayer, is disposed on one side of the mesa structure, and is electrically connected to outside; and an electrode pad peripheral portion including a first rising surface which is in contact with the outer edge of the electrode pad portion on the exit end surface side and rises along the stacking direction from the electrode pad portion, in which a lower surface of the electrode pad portion is higher than the upper surface of the mesa structure of the first semiconductor multilayer.