Multilayer Stack Patterning to Prevent Photoresist Residues
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Solution Overview
Problem
Conventional methods for patterning metallic layers in quantum computing devices face issues with hardened photoresist residues at the edges of patterned features, which can hinder uniform layer formation and affect electromagnetic properties, leading to decoherence and loss of qubit coherence or resonator quality.
Innovation Solution
A three-layer stack process is employed, where a protective layer is deposited between the metallic layer and the supporting layer, and a photoresist layer is deposited on the supporting layer, forming an undercut profile to prevent direct contact between the hardened photoresist and the metallic layer, and using reactive ion etching to anisotropically remove the protective layer, thereby reducing residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a photoresist layer is deposited directly on a metallic layer for patterning, then the patterning process can be simplified, but hardened photoresist residues form at the edges of patterned features
Solution Approach 1:
A supporting layer is introduced as an intermediary between the photoresist layer and the metallic layer. This supporting layer prevents direct contact between the photoresist and metallic layer, thereby eliminating the formation of hardened photoresist residues at the edges of patterned features while still enabling the patterning process to proceed
2Manufacturing precision
If photoresist residues are present at the edges of patterned features, then the patterning can be completed, but uniform layer formation is hindered and electromagnetic properties are affected
Solution Approach 1:
The supporting layer acts as a mediator that prevents photoresist residues from contaminating the metallic layer, thereby ensuring both uniform layer formation and preserved electromagnetic properties of the quantum computing device
3Object-generated harmful factors
If a supporting layer is introduced between the photoresist and metallic layer, then photoresist residue formation is prevented, but the device structure becomes more complex
Solution Approach 1:
The original single-layer structure (photoresist on metallic layer) is segmented into two separate layers (photoresist on supporting layer on metallic layer). This segmentation allows the supporting layer to perform the specific function of preventing photoresist residue formation while maintaining the overall patterning functionality
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 provides improved protection against residues, ensuring cleaner edges and reduced decoherence, enhancing the coherence time and quality factor of quantum information processing devices by preventing dielectric/metallic residues from contacting the metallic structure.
Implementation Method 1
the supporting layer is soluble in the developer
Implementation Method 2
anisotropically dry etching the substrate
Data Source
AI summary
A method of fabricating a device is presented. The method includes forming a multilayer stack (101′, 102′, 103′) on a substrate (10′, 100′) which has a principal surface. The multilayer stack includes a supporting layer (102′) formed over the principal surface of the substrate and a photoresist layer (103′) formed on the supporting layer, patterning the multilayer stack to form at least one opening such that the photoresist layer is undercut by the supporting layer and anisotropically dry etching the substrate.