Compensating Deposition Non-Uniformities in Quantum Circuit Elements
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Solution Overview
Problem
Quantum computing circuit elements, such as Josephson junctions, face non-uniform deposition issues due to variations in film thickness across substrates, leading to inconsistent junction resistance and performance, which affects the controllability and reproducibility of qubits.
Innovation Solution
A uniformity function is applied to modify lithography mask write files to compensate for non-uniform deposition processes, adjusting geometric features and deposition parameters to achieve consistent film thickness and resistance across the substrate, using data processing to generate and apply these functions to multiple device layouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography mask write files are used without modification, then the fabrication process is simple and quick, but the deposited film thickness is non-uniform across the substrate, leading to inconsistent junction resistance and device performance
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing deposition uniformity data from test structures before actual device fabrication. This uniformity data is then used to modify lithography mask write files in advance, compensating for anticipated deposition non-uniformities. This approach eliminates the need for manual calibration during production while achieving uniform film thickness across the substrate.
Solution Approach 2:
The patent changes parameters in the lithography mask write file based on deposition uniformity measurements. Specifically, it adjusts geometric features (such as feature dimensions and positions) and deposition parameters (such as deposition rate and timing) to compensate for non-uniform deposition. This parameter modification ensures that the final deposited structures have consistent dimensions and properties across the entire substrate.
2Manufacturing precision
If manual calibration is performed for each device layout to achieve uniform deposition, then deposition uniformity improves, but the fabrication time and complexity increase significantly
Solution Approach 1:
The patent creates a reusable uniformity function that captures deposition non-uniformity characteristics. This function serves as a template that can be automatically applied to multiple different device layouts without requiring manual recalibration for each case. The uniformity function is derived from test structure measurements and then copied/adapted across various production designs, dramatically reducing calibration time while maintaining junction resistance uniformity.
Solution Approach 2:
The system performs self-service by automatically modifying lithography mask write files using the uniformity function without requiring manual intervention. The process autonomously adjusts mask parameters based on stored uniformity data, eliminating the need for operators to perform time-consuming manual calibration for each device layout while achieving consistent deposition uniformity.
3Manufacturing precision
If deposition parameters are kept constant for all features, then the deposition process is simple and fast, but features at different locations on the substrate receive non-uniform film thickness
Solution Approach 1:
The patent applies local quality by assigning different deposition parameters to different regions or features on the substrate based on their specific location and requirements. The uniformity function modifies deposition parameters (such as deposition rate, timing, and beam intensity) locally for each feature or region to compensate for position-dependent non-uniformities. This ensures that each location receives the appropriate deposition conditions to achieve uniform film thickness across the entire substrate.
Data Source
AI summary
A method of fabricating a circuit element, such as a quantum computing circuit element, including obtaining a lithography mask write file that includes mask information characterizing one or more mask features, obtaining a uniformity function that is configured to modify the mask information to compensate for a non-uniform deposition process, applying the uniformity function to the lithography mask write to obtain a modified lithography mask write file, and performing lithography as directed by the modified lithography mask write file.