Co Buffer Layer for Reliable Via Contacts in Interconnects
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Solution Overview
Problem
Existing semiconductor interconnect structures face issues with poor mechanical integrity and thermal cycling resistance due to the use of low k dielectric materials, particularly exacerbated by argon sputtering techniques that damage these materials and lead to high metal-to-metal leakage and misaligned via patterns, making integration with ultra-low k dielectrics challenging.
Innovation Solution
A Co-containing buffer layer is introduced at the interface between the upper and lower interconnect levels, eliminating the need for via gouging features and thus avoiding argon sputtering damage, while enhancing mechanical strength and adhesion, thereby improving the reliability and strength of the via-to-wire connection without increasing resistance or processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If argon sputtering technique is used to create via gouging features, then mechanical strength of contact stud is increased, but low k dielectric material is damaged
Solution Approach 1:
A Co-containing buffer layer is introduced as an intermediary between the conductive feature and the opening. This buffer layer serves as a mediator that provides the necessary mechanical strength and adhesion without requiring argon sputtering damage to the dielectric material. The buffer layer absorbs the mechanical stress and creates a strong interface without the harmful side effects of sputtering.
Solution Approach 2:
The invention extracts and eliminates the need for via gouging features and argon sputtering processes. By removing this damaging step entirely and replacing it with a Co-containing buffer layer formed by selective deposition, the patent achieves mechanical strength enhancement without dielectric material damage.
2Strength
If via gouging features are created by argon sputtering, then adhesion strength is improved, but metal-to-metal leakage increases
Solution Approach 1:
The Co-containing buffer layer acts as an intermediary that provides adhesion strength without creating the conditions for metal-to-metal leakage. The buffer layer forms a controlled interface that prevents direct metal-to-metal contact while maintaining strong adhesion, thereby eliminating the leakage problem associated with sputtered gouging features.
3Ease of manufacture
If conventional damascene process is used, then manufacturing simplicity is maintained, but mechanical integrity of metal studs is poor
Solution Approach 1:
The invention segments the interface structure by introducing a distinct Co-containing buffer layer between the conductive feature and the opening. This segmentation allows each layer to perform its specific function: the buffer layer provides mechanical integrity and adhesion, while the conductive feature maintains electrical conductivity. The segmented structure enhances mechanical integrity without significantly complicating the manufacturing process.
4Speed
If low k dielectric materials are used, then RC delay is reduced, but thermal cycling resistance deteriorates
Solution Approach 1:
The invention applies local quality enhancement by introducing a Co-containing buffer layer specifically at the via interface where mechanical strength is needed. This localized intervention allows the use of low k dielectric materials in the bulk for reduced RC delay, while the buffer layer provides enhanced thermal cycling resistance at the critical interface region.
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 Co-containing buffer layer enhances the mechanical and adhesion strength of the via-to-wire connection, reduces metal-to-metal leakage, and prevents dielectric damage, resulting in improved reliability and strength without the drawbacks of prior art methods, especially benefiting misaligned via patterns and ultra-low k dielectric materials.
Implementation Method 1
a Co-containing buffer layer which is formed selectively in, and is restricted to, the interface between the opening of an upper interconnect level and the underlying conductive feature of a lower interconnect level
Data Source
AI summary
A reliable and mechanical strong interconnect structure is provided that does not include gouging features in the bottom of the an opening, particularly at a via bottom. Instead, the interconnect structures of the present invention utilize a Co-containing buffer layer that is selectively deposited on exposed surfaces of the conductive features that are located in a lower interconnect level. The selective deposition is performed through at least one opening that is present in a dielectric material of an upper interconnect level. The selective deposition is performed by electroplating or electroless plating. The Co-containing buffer layer comprises Co and at least one of P and B. W may optionally be also present in the Co-containing buffer layer.