Probing Pad Reinforcement Pattern for Copper Oxidation Prevention
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Solution Overview
Problem
The existing methods for wafer probing in semiconductor integrated circuits often result in damage to the underlying copper metal layer due to excessive probing force, especially when using low-k insulation layers, leading to oxidation and potential chip damage.
Innovation Solution
A method involving the formation of an inlaid metal wiring with a reinforcement pattern covered by a passivation dielectric film, where a conductive pad is created to fill the inter-spaces of the pattern, allowing the probe tip to penetrate the pad instead of the underlying copper layer, thereby reducing stress and preventing exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a probe tip directly contacts the aluminum pad through the via opening, then good electrical contact is achieved, but the underlying copper metal layer may be exposed and oxidized due to excessive probing force
Solution Approach 1:
A probe protection layer is introduced as an intermediary between the probe tip and the underlying copper metal layer. This protection layer has higher mechanical strength than the passivation dielectric film, allowing it to absorb excessive probing force and prevent the probe tip from penetrating through the aluminum pad and exposing the copper layer, thus eliminating the harmful oxidation effect while maintaining reliable electrical contact
2Reliability
If probing force is increased to ensure good contact, then electrical connection reliability improves, but damage to the copper metal layer and insulation layer occurs
Solution Approach 1:
The probe protection layer is designed with higher mechanical strength than the passivation dielectric film to serve as a cushioning layer before the probe tip can cause damage. This protection layer absorbs and distributes the excessive probing force, preventing the probe tip from penetrating through the aluminum pad and damaging the underlying copper metal layer and insulation layer, thus protecting the chip structure while ensuring reliable electrical contact
Data Source
AI summary
A method for fabricating a probing pad is disclosed. A substrate having thereon a dielectric layer is provided. An inlaid metal wiring is formed in the dielectric layer. The inlaid metal wiring and the dielectric layer are covered with a passivation dielectric film. A portion of the passivation dielectric film is then etched away to form a reinforcement pattern on the inlaid metal wiring. The reinforcement pattern has inter-space that exposes a portion of the underlying inlaid metal wiring. A conductive pad is formed over the reinforcement pattern and the passivation dielectric film. The conductive pad fills the inter-space of the reinforcement pattern.