Pillar Stop Bonding Structure for Uniform Chip Separation
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Solution Overview
Problem
Current quantum computing technologies face challenges in achieving precise and uniform chip-to-chip separation in stacked devices, which affects the repeatability and accuracy of qubit coupling, leading to inefficiencies in quantum information processing.
Innovation Solution
The use of pillars as stops during the bonding process between substrates, where the pillars act as compressible stops to maintain a predetermined separation distance and provide electrical connections, improving the precision and uniformity of the separation and coupling between qubits and control circuit elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bonding methods are used without pillars, then the bonding process is simpler, but the separation distance between substrates lacks precision and uniformity
Solution Approach 1:
Pillars are introduced as intermediary elements between the first and second substrates. These pillars serve as physical stops that define and maintain the precise separation distance during bonding. The pillars are positioned at specific locations on the substrates and prevent the substrates from coming into direct contact, thereby ensuring uniform separation without requiring complex bonding control mechanisms.
Solution Approach 2:
The invention changes the physical parameter of separation distance by using pillars with specific heights. By controlling the height parameter of the pillars, the separation distance between substrates is precisely determined. This transforms the separation distance control from a process parameter to a structural parameter, improving precision and uniformity.
2Manufacturing precision
If pillars with large cross-sectional area are used, then the separation distance precision is improved, but the electrical connection area for qubits is reduced
Solution Approach 1:
The bonding interface is segmented into multiple discrete pillar locations rather than using a continuous structure. This segmentation allows the pillars to be positioned strategically at locations that do not interfere with the qubit electrical connection areas. The bump bonds are also positioned at separate locations to provide electrical connections, thereby resolving the conflict between separation precision and connection area.
Solution Approach 2:
Different regions of the substrate are assigned different functions: pillars are placed in regions dedicated to separation control, while bump bonds are placed in regions dedicated to electrical connections. This local differentiation ensures that the pillars' cross-sectional area does not encroach on the electrical connection areas, as each component occupies its own optimized zone on the substrate.
3Manufacturing precision
If multiple pillars are used for precise separation, then the separation precision is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The pillars are formed on the substrates before the bonding process. This preliminary formation allows the pillars to be precisely positioned and their heights to be controlled during the substrate fabrication stage, rather than requiring complex control during bonding. The pre-formed pillars serve as ready-made separation stops, simplifying the overall manufacturing process while maintaining high precision.
Data Source
AI summary
A stacked device including a first substrate that includes a quantum information processing device, a second substrate bonded to the first substrate, and multiple bump bonds and at least one pillar between the first substrate and the second substrate. Each bump bond of the multiple bump bonds provides an electrical connection between the first substrate and the second substrate. At least one pillar defines a separation distance between a first surface of the first substrate and a first surface of the second substrate. A cross-sectional area of each pillar is greater than a cross-sectional area of each bump bond of the multiple bump bonds, where the cross-sectional area of each pillar and of each bump bond is defined along a plane parallel to the first surface of the first substrate or to the first surface of the second substrate.