Multilayer Stack Patterning to Prevent Photoresist Edge Residues

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Solution Overview

Problem

Existing methods for patterning metallic layers in quantum computing devices face challenges due to hardened photoresist residues, which can hinder the uniform formation of subsequent layers and affect electromagnetic properties.

Innovation Solution

A three-layer structure is used, comprising a protective layer, a supporting layer, and a photoresist layer, where the protective layer provides additional protection against residues and facilitates easier solvent entry for removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-layer photoresist structure is used for patterning metallic layers, then the process is simple, but hardened photoresist residues remain near the edges of patterned features

Engineering Contradiction:

Improvepatterning process simplicityVSAvoidhardened photoresist residues

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent divides the single photoresist layer into two separate layers: a supporting layer in direct contact with the metallic layer, and a photoresist layer on top. This segmentation allows the supporting layer to remain as a barrier preventing photoresist residues from contacting the metallic layer, while the photoresist layer can be completely removed after patterning. The supporting layer is patterned along with the photoresist layer, providing edge protection throughout the process.

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If the photoresist layer is made thicker to prevent residue formation, then edge protection improves, but solvent penetration and removal become more difficult

Engineering Contradiction:

Improveedge protection against residuesVSAvoidsolvent entry and photoresist removal

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

By separating the protective function into a thin supporting layer (providing edge protection) from the thicker photoresist layer (providing patterning coverage), the patent enables complete solvent penetration of the photoresist layer without requiring excessive thickness for protection. The supporting layer, being thin and in direct contact with the metallic layer, provides sufficient barrier protection while the photoresist layer above it can be fully removed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The supporting layer acts as an intermediary barrier between the metallic layer and the photoresist layer. It provides a protective interface that prevents photoresist residues from directly contacting the metallic layer, while still allowing the process to use standard photoresist thicknesses that are easily removable with solvents.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If photoresist residues are allowed to remain on the metallic layer, then the fabrication process is faster, but subsequent layer formation becomes non-uniform and electromagnetic properties are affected

Engineering Contradiction:

Improvefabrication speedVSAvoiduniformity of subsequent layers

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the protective function from the photoresist function, allowing complete removal of the photoresist layer while maintaining protection during fabrication. The supporting layer remains as a thin protective barrier that does not interfere with subsequent layer formation, enabling both fast processing and high precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent converts the potential harm of photoresist residues into a benefit by using the supporting layer as a sacrificial barrier. The supporting layer is designed to be patterned along with the photoresist, providing edge protection during the entire process, and then completely removed afterward, leaving no harmful residues while having served its protective purpose.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces the occurrence of hardened photoresist residues near the edges of patterned metallic layers, improving the cleanliness and quality of the patterned features, which is crucial for quantum information devices.

Implementation Method 1

patterning the multilayer stack to form at least one opening

Methodology Applied

Scientific EffectPhotolithography: Photopolymerisation

Implementation Method 2

the photoresist layer is undercut by the supporting layer

Methodology Applied

Scientific EffectSelective dissolution: Solvation

Implementation Method 3

patterning the multilayer stack may comprise developing the photoresist layer using a developer

Methodology Applied

Scientific EffectPlasma oxidation: Oxidation

Implementation Method 4

anisotropically dry etching the substrate

Methodology Applied

Scientific EffectAnisotropic etching:

Data Source

PatentUS12288687B2Fabricating a device using a multilayer stack

Publication Date: 2025.04.29 GOOGLE LLC

AI summary

A method of fabricating a device is presented. The method includes forming a multilayer stack on a substrate which has a principal surface. The multilayer stack includes a supporting layer formed over the principal surface of the substrate and a photoresist layer 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.