Air Bridge Flip-Chip Mounting With Sacrificial Layer Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods face challenges in flip-chip mounting chips with air bridges due to the fragility of air bridges and the difficulty in removing sacrificial layers without damaging underlying metal layers, particularly in superconducting quantum circuits.
Innovation Solution
A method involving depositing a conductive layer to form an air bridge on a sacrificial layer, mounting the chip with the sacrificial layer intact, and then removing the sacrificial layer underneath the air bridge, using a reinforced photoresist layer to support the air bridge during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the sacrificial layer is removed before mounting the chip, then the air bridge structure is formed, but the air bridge becomes fragile and cannot withstand subsequent processing
Solution Approach 1:
The sacrificial layer is removed in advance during chip fabrication while the air bridge is still supported, creating the air bridge structure beforehand. The chip is then mounted with this pre-formed structure, and the sacrificial layer supporting the air bridge during mounting is removed after mounting completes, allowing the air bridge to maintain its shape throughout processing
Solution Approach 2:
The sacrificial layer serves as a temporary intermediary support structure during chip mounting. It provides mechanical support to the air bridge during the mounting process, then is removed after mounting to leave the final air bridge structure without the intermediary
2Shape
If the sacrificial layer is removed early to form the air bridge, then the air bridge structure is created, but underlying metal layers are damaged during subsequent processing
Solution Approach 1:
The air bridge structure is formed preliminarily on the sacrificial layer during chip fabrication before mounting. This preliminary formation allows the air bridge to be created in a controlled environment where underlying metal layers are protected, and the structure is then mounted as a complete unit
Solution Approach 2:
The sacrificial layer acts as a protective intermediary between the air bridge and underlying metal layers during mounting and subsequent processing. It shields the vulnerable metal layers from damage while allowing the air bridge to be formed and mounted, then is removed after the metal layers are protected
3Shape
If a traditional air bridge manufacturing method is used, then the air bridge is formed by removing interlayer dielectric, but the chip cannot be flip-chip mounted due to fragility
Solution Approach 1:
The manufacturing approach transitions from forming the air bridge by removing material in the vertical dimension (interlayer dielectric removal) to forming it by depositing material on a sacrificial layer, creating a supported structure that extends in multiple dimensions and can withstand mounting operations
Solution Approach 2:
The sacrificial layer serves as a temporary intermediary support that enables flip-chip mounting by providing mechanical strength during the mounting process, then is removed to leave the final air bridge structure
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
Enables stable flip-chip mounting of chips with air bridges, enhancing mechanical strength and allowing for subsequent processing without damaging underlying metal layers, thus facilitating the integration of superconducting quantum circuits.
Implementation Method 1
forming (depositing) a conductive layer, which is to be an air bridge, on a sacrificial layer
Data Source
AI summary
A device manufacturing method includes: forming a conductive layer, which is to be an air bridge, on a sacrificial layer in a first surface of a chip to pattern form the conductive layer; removing the sacrificial layer other than the sacrificial layer underneath the air bridge; mounting the chip with the sacrificial layer left underneath the air bridge on a board such that the first surface of the chip opposes the board; and removing the sacrificial layer left underneath the air bridge.