Qubit Chip Mounting Warpage Control via Localized Heating
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Solution Overview
Problem
The mounting process of a qubit chip over a first substrate and then a first substrate over a second substrate results in warpage due to differing linear expansion coefficients, leading to increased temperature of the qubit chip and changes in its characteristics when the second bump is heated, affecting positional accuracy and device performance.
Innovation Solution
The method involves mounting the qubit chip over a first substrate using a first bump and locally heating a second bump at a position not overlapping the qubit chip, with no joining member at overlapping positions, to minimize temperature increase and maintain qubit chip characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first substrate is mounted over the second substrate first using the second bump, then the mounting process can be completed, but warpage occurs in the first substrate and second substrate due to difference in linear expansion coefficient, making it difficult to mount the qubit chip with high positional accuracy
Solution Approach 1:
The qubit chip is mounted on the first substrate before the first substrate is mounted on the second substrate. This preliminary mounting action ensures that the qubit chip is positioned with high accuracy on the first substrate before any warpage occurs during the subsequent mounting of the first substrate on the second substrate.
2Ease of manufacture
If the second bump is heated using a heating furnace to mount the first substrate over the second substrate, then the mounting can be achieved, but the qubit chip mounted on the first substrate is also heated causing temperature increase and change in characteristics
Solution Approach 1:
The heating is applied locally only to the region where the second bump is located, rather than heating the entire assembly. This localized heating approach allows the second bump to be reflowed for mounting while the qubit chip, being in a different location, is not exposed to excessive heat that would change its characteristics.
Solution Approach 2:
The heating process is segmented into a localized region around the second bump rather than applying uniform heat across the entire structure. This segmentation of the heating zone enables selective heating of only the necessary area for mounting while preserving the thermal sensitivity of the qubit chip.
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 suppresses changes in qubit chip characteristics by controlling temperature fluctuations, ensuring precise positioning and maintaining device integrity.
Implementation Method 1
The process of mounting the first substrate over the second substrate using the second bump is performed by heating the second bump
Implementation Method 2
heating the second bump, thereby mounting the first substrate over the second substrate
Implementation Method 3
warpage occurs in the first substrate and in the second substrate due to a difference in linear expansion coefficient between the first substrate and the second substrate
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3C
AI summary
A method for manufacturing a quantum device, the method includes: mounting a qubit chip over a first substrate by using a first bump; and mounting the first substrate over a second substrate by, after mounting the qubit chip, locally heating a second bump provided at a position that does not overlap the qubit chip in plan view, wherein no joining member that joins the first substrate and the second substrate is provided between the first substrate and the second substrate at a position that overlaps the qubit chip in plan view.