Curved Pad Interconnects for Passivation Integrity
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Solution Overview
Problem
In semiconductor device fabrication, the reliability of wire bonding pads is compromised due to metal corrosion during thermal cycles, leading to passivation stack destruction and moisture ingress, which affects the integrity and performance of the device.
Innovation Solution
A method of forming semiconductor devices with pad interconnects that lack 90° angles and angled structures, using a pad dielectric layer and conductive layer to create a pattern that enhances the integrity of the passivation layer, thereby reducing corrosion and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pad interconnect patterns with 90° angles are used, then manufacturing is simpler, but the passivation layer integrity deteriorates during thermal cycles
Solution Approach 1:
The patent replaces conventional 90° angled pad interconnect patterns with curved or rounded patterns. This curvature eliminates the sharp corners that act as stress concentration points during thermal cycling, thereby preventing passivation layer destruction while maintaining manufacturability through standard photolithography processes.
2Reliability
If conventional pad patterns with sharp corners are used, then fabrication is easier, but corrosion resistance deteriorates due to moisture ingress
Solution Approach 1:
The curved pad interconnect patterns eliminate sharp corners that create stress concentrations and facilitate moisture ingress. The rounded geometry provides uniform stress distribution during thermal expansion and contraction, preventing passivation layer failure and reducing corrosion risk while remaining compatible with standard fabrication processes.
3Reliability
If standard thermal cycle testing is performed on conventional devices, then reliability assessment is achieved, but device failure occurs due to passivation destruction
Solution Approach 1:
The curved pad interconnect design fundamentally changes the stress distribution pattern during thermal cycling. By eliminating 90° corners, the design prevents stress concentration that would otherwise cause passivation layer cracking and destruction, allowing devices to successfully pass standard thermal cycle reliability testing.
Data Source
AI summary
Device and method for forming a device are presented. A substrate having circuit component and a back-end-of-line (BEOL) dielectric layer with interconnects is provided. A pad dielectric layer is formed over the BEOL dielectric layer. The pad dielectric layer includes a pad via opening which exposes a surface of one of the interconnects in the BEOL dielectric layer. A pad interconnect is formed on the pad dielectric layer and the pad interconnect is coupled to one of the interconnect in the BEOL dielectric by a pad via contact in the pad via opening. The pad interconnect comprises a pad interconnect pattern which is devoid of 90° angles and any angled structures contained in the pad interconnect pattern less than 90°. A passivation layer is formed on the substrate. The passivation layer lines the pad interconnect and covers an exposed surface of the pad dielectric layer.