Bond Pad Protective Layer for Fluorine Byproduct Isolation
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Solution Overview
Problem
During integrated chip fabrication, bond pads are prone to damage from fluorine-based etching byproducts, leading to electrical failures and reduced reliability due to the formation of compounds like AlOH3 and 3HF, and subsequent use of non-fluorine based etchants can cause surface roughness and adhesion issues, slowing down the process and increasing costs.
Innovation Solution
A protective layer is formed over the bond pad, comprising materials like titanium nitride, which has high etching selectivity, allowing for the separation of etching byproducts from the bond pad, thereby preventing damage and enabling a smooth surface through a wet etching process without the need for non-fluorine based etchants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fluorine-based etching is used to form openings, then etching performance is improved, but etching byproducts damage the bond pad causing electrical failure
Solution Approach 1:
A protective layer is introduced as an intermediary between the bond pad and the fluorine-based etching process. This protective layer selectively protects the bond pad from fluorine-based etching byproducts while allowing the etching process to proceed at high speed on the passivation layer. The protective layer acts as a mediator that enables the use of fast fluorine-based etching without compromising bond pad integrity.
Solution Approach 2:
The protective layer is formed on the bond pad before the fluorine-based etching process. This preliminary action prepares the bond pad by providing a protective barrier that prevents damage from upcoming etching byproducts, allowing the subsequent etching process to be performed without risk of bond pad degradation.
2Reliability
If non-fluorine based etchants are used to remove byproducts, then bond pad damage is prevented, but surface roughness and adhesion issues occur
Solution Approach 1:
The protective layer serves as a mediator that prevents direct contact between non-fluorine based etchants and the bond pad. This intermediary barrier allows the use of non-fluorine based etchants to remove fluorine-based etching byproducts from the passivation layer without causing surface roughness or adhesion issues on the bond pad itself.
3Reliability
If additional etching steps and dedicated chambers are used, then byproduct removal is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The protective layer enables a single etching chamber to perform multiple functions: it can handle both the fluorine-based etching of the passivation layer and the removal of byproducts, eliminating the need for dedicated chambers. The protective layer's selective protection property allows the same chamber to process different layers with different requirements without cross-contamination or equipment specialization.
Solution Approach 2:
The use of the protective layer allows combining multiple etching steps that would otherwise require separate dedicated chambers into a single integrated process. The protective layer enables the merging of fluorine-based etching and byproduct removal operations in one chamber, reducing manufacturing complexity and equipment requirements.
4Reliability
If additional etching steps are used, then byproduct removal is improved, but manufacturing time increases
Solution Approach 1:
The protective layer enables a single etching chamber to perform multiple functions: it can handle both the fluorine-based etching of the passivation layer and the removal of byproducts, eliminating the need for dedicated chambers. The protective layer's selective protection property allows the same chamber to process different layers with different requirements without cross-contamination or equipment specialization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The protective layer effectively mitigates the formation of etching byproducts, ensuring a smooth bond pad surface, improving reliability and throughput by eliminating the need for additional etching steps and dedicated chambers, thus adhering to q-time requirements.
Implementation Method 1
A protective layer is formed over the bond pad, comprising materials like titanium nitride, which has high etching selectivity, allowing for the separation of etching byproducts from the bond pad
Implementation Method 2
enabling a smooth surface through a wet etching process without the need for non-fluorine based etchants
Data Source
AI summary
The present disclosure, in some embodiments, relates to an integrated chip. The integrated chip includes a bond pad disposed over a substrate and a passivation structure disposed over the substrate and the bond pad. The passivation structure has one or more sidewalls directly over the bond pad. A protective layer is disposed directly between the passivation structure and the bond pad. The passivation structure extends from directly over the protective layer to laterally past a sidewall of the protective layer that faces a central region of the bond pad.