Semiconductor Light Emitting Device Metal Pillar Insulating Film
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Solution Overview
Problem
Existing semiconductor light emitting devices face challenges in downsizing while maintaining reliability, particularly in flip chip mounting where solder wettability issues lead to tombstone defects and electrical shorts due to exposed conductive surfaces during the mounting process.
Innovation Solution
The semiconductor light emitting device incorporates a structure with insulating films on the side faces of metal pillars, which have poorer solder wettability than the metal, and a resin layer that covers the pillars, preventing solder wetting and exposure, thus avoiding bonding defects and shorts. This structure includes a semiconductor layer with a light emitting layer, electrodes, interconnect layers, and metal pillars connected by insulating films and a resin layer for enhanced mechanical strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to perform flip chip mounting of LED chip, then electrical connection is achieved, but tombstone defects and electrical shorts occur due to poor solder wettability and exposed conductive surfaces
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the solder and the conductive metal pillar. This insulating film has better solder wettability than the metal pillar surface, allowing solder to properly wet and bond to the pillar without causing tombstone defects or electrical shorts to adjacent conductors.
Solution Approach 2:
The insulating film is selectively formed only on specific portions of the metal pillar that require solder bonding. This localized treatment provides different surface properties in different regions: the insulating film-covered regions have good solder wettability for reliable bonding, while other regions maintain their original metal properties.
2Volume of moving object
If device size is reduced for downsizing, then integration density increases, but manufacturing precision and reliability become more difficult to maintain
Solution Approach 1:
The solder wettability parameter of the metal pillar surface is changed by forming an insulating film layer. This parameter change enables reliable solder bonding even in downsized devices where manufacturing tolerances are tighter and precision is more critical.
3Reliability
If metal pillars are exposed without insulation, then electrical connectivity is maintained, but solder wets the metal surface causing bonding defects
Solution Approach 1:
The insulating film serves as a mediator between the solder and metal pillar, providing a surface that promotes proper solder wetting and bonding while preventing the harmful effects of direct solder contact with the metal surface, such as tombstone defects and electrical shorts.
Data Source
AI summary
According to one embodiment, a semiconductor light emitting device includes a semiconductor layer, a first electrode, a second electrode, an insulating layer, a first interconnect layer, a second interconnect layer, a first metal pillar, a second metal pillar, a film covering a side face of the first metal pillar and a side face of the second metal pillar, and a resin layer. The semiconductor layer includes a light emitting layer, a first major surface, and a second major surface formed on a side opposite to the first major surface. The film has a solder wettability poorer than a solder wettability of the first metal pillar and a solder wettability of the second metal pillar. The resin layer covers at least part of the film.