Passivation Film Tapering for Semiconductor Electrode Crack Resistance
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Solution Overview
Problem
Existing semiconductor devices face reliability issues due to cracks in the passivation film caused by thermal stress, leading to moisture ingress and corrosion of the surface electrode during temperature humidity bias (THB) reliability tests.
Innovation Solution
A semiconductor device design featuring a semiconductor substrate with an insulating film, a first surface electrode, and a passivation film with a tapered cover portion that becomes wider as it approaches the semiconductor substrate, along with a second metal portion with higher corrosion resistance, to reduce stress concentrations and prevent moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passivation film covers the vertically rising surface electrode, then the electrode is protected, but the passivation film develops cracks due to stress concentration
Solution Approach 1:
The surface electrode is designed with a curved side surface instead of a vertical profile. The curvature radius is specifically controlled to be 0.5-2.0 times the passivation film thickness, creating a gradual transition that eliminates stress concentration points and prevents crack formation in the passivation film.
Solution Approach 2:
The invention changes the geometric parameters of the surface electrode by controlling the curvature radius of its side surface. This parameter modification allows the electrode to maintain protective coverage while eliminating the stress concentration that causes passivation film cracking.
2Ease of manufacture
If a simple single-layer electrode structure is used, then the manufacturing is simpler, but the corrosion resistance is insufficient
Solution Approach 1:
The surface electrode is constructed as a composite structure with multiple metal layers, each providing different functional properties. The first metal layer provides structural foundation while the second metal layer enhances corrosion resistance, creating a synergistic effect that improves overall electrode reliability.
Solution Approach 2:
The electrode structure is optimized with different metal materials at different locations and depths. The second metal layer with superior corrosion resistance is positioned at the critical interface with the passivation film, providing localized protection where it is most needed against moisture ingress.
Data Source
AI summary
The object is to provide a technology capable of enhancing the reliability of a semiconductor device. A semiconductor device includes: an insulating film along an upper surface of a semiconductor substrate; a first surface electrode selectively provided on the insulating film; and a passivation film covering the insulating film and the first surface electrode. The passivation film includes a cover portion covering the first surface electrode, the cover portion having a tapered shape with at least one of a first structure or a second structure such that the cover portion becomes wider as the cover portion is closer to the semiconductor substrate in a cross-sectional view.