Superconductor Interconnects Oxide Removal
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Solution Overview
Problem
The fabrication of superconducting circuits faces challenges in mass production due to oxidation of conductive contacts and lines during the dual damascene process, leading to degraded performance and reduced yield, uniformity, and repeatability, as well as high-loss interface oxides between dielectric and superconducting traces.
Innovation Solution
A single-chamber physical vapor deposition system that integrates a precleaning process using Inductively Coupled Plasma (ICP) mode for oxide removal and Self-Ionized Plasma (SIP) mode for metal deposition, eliminating exposure to oxidizing environments and reducing contamination from transfer and buffer chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is transferred between chambers for deposition, then the deposition process can be performed, but oxidation of conductive contacts and lines occurs during transfer and exposure, degrading performance
Solution Approach 1:
The patent combines the precleaning process and superconducting metal deposition process into a single deposition chamber. The chamber is configured to perform precleaning (removal of surface oxides and contaminants) followed by deposition without requiring substrate transfer to another chamber, thereby eliminating oxidation during transfer and improving circuit performance
Solution Approach 2:
The deposition chamber maintains an inert or reducing atmosphere throughout both the precleaning and deposition processes. This controlled environment prevents oxidation of the substrate and newly deposited superconducting metals, addressing the harmful oxidation effect that occurs during chamber transfer
2Manufacturing precision
If multiple chambers are used for precleaning and deposition, then process specialization is achieved, but contamination from transfer and buffer chambers increases
Solution Approach 1:
The patent merges the precleaning and deposition functions into a single chamber system, eliminating the need for substrate transfer through buffer chambers. This integration removes the source of contamination that would otherwise degrade the uniformity and yield of Josephson Junctions
3Ease of manufacture
If interface oxides are present between dielectric and superconducting traces, then the structure can be formed, but loss tangent increases
Solution Approach 1:
The patent performs precleaning as a preliminary action before deposition to remove interface oxides between the dielectric layer and superconducting traces. This pre-removal of oxides prevents energy loss in the final superconducting structure while maintaining ease of manufacture through an integrated process
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
This approach effectively eliminates surface oxides and contaminants, improving the critical current performance of interconnects, yield, and uniformity of Josephson Junctions, and reducing the effective loss tangent of superconducting circuit elements by eliminating interface oxides, as validated by SIMS data.
Implementation Method 1
performing a cleaning process on the top surface of the dielectric layer and in the interconnect opening while in the deposition chamber
Implementation Method 2
depositing a superconducting metal in the interconnect opening while in the deposition chamber to form a superconducting element
Implementation Method 3
setting the PVD chamber to a Self Ionized Plasma (SIP) mode resulting in the depositing of superconducting niobium in the interconnect opening from the slab of superconducting niobium target material
Data Source
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AI summary
A method is provided of forming a superconductor interconnect structure. The method comprises forming a dielectric layer overlying a substrate, forming an interconnect opening in the dielectric layer, and moving the substrate to a deposition chamber. The method further comprises performing a cleaning process on the top surface of the dielectric layer and in the interconnect opening while in the deposition chamber, and depositing a superconducting metal in the interconnect opening while in the deposition chamber to form a superconducting element in the superconductor interconnect structure.