Pillar Stop Structure for Precise Chip-to-Chip Separation
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Solution Overview
Problem
Existing quantum computing technologies face challenges in achieving precise and uniform chip-to-chip separation in stacked devices, which affects the repeatability and precision of electrical connections between substrates, limiting the density and coupling of superconducting qubits.
Innovation Solution
The use of pillars as compressible stops during the bonding process, combined with superconducting bump bonds, to maintain a consistent separation distance and improve the accuracy of chip-to-chip alignment, allowing for precise electrical connections and improved coupling between 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 chip-to-chip separation distance is imprecise and non-uniform
Solution Approach 1:
Pillars are pre-formed on the substrate before the bonding process. These pillars serve as predetermined stops that define the exact separation distance between chips, ensuring precise and uniform spacing is established before bonding occurs, thereby resolving the precision issue without requiring complex real-time control during bonding
Solution Approach 2:
Pillars act as intermediary elements between the substrate and the bonding interface. They mediate the separation distance by physically limiting how close the bonded chip can approach the substrate, providing a simple mechanical stop that ensures uniform spacing without complicating the overall bonding structure
2Manufacturing precision
If pillars with large cross-sectional area are used, then the separation distance is more precise, but the pillar structure becomes more prominent and may interfere with circuit elements
Solution Approach 1:
Pillars are strategically positioned only in specific locations where separation distance control is critical, rather than covering the entire substrate surface. This localized approach provides precise separation control where needed while minimizing the total pillar area and avoiding interference with circuit elements in other regions
Solution Approach 2:
The pillar structure is designed with asymmetric dimensions where the cross-sectional area is optimized to provide sufficient stopping force for precise separation control, while the height and positioning are asymmetrically adjusted to clear circuit elements and avoid interference, thereby balancing precision requirements with spatial constraints
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 enhances the repeatability, precision, and uniformity of substrate separation, leading to better coupling and reduced energy loss in quantum computing devices, thereby increasing the density and functionality of superconducting qubits.
Implementation Method 1
The bonding of the first substrate and the second substrate includes applying a force between the first substrate and the second substrate to compress the multiple bump bonds to the same thickness as the thickness of the at least one pillar
Implementation Method 2
Each pillar of the one or more pillars has a thickness that corresponds to a predetermined separation distance between the first substrate and the second substrate when the first substrate and the second substrate are bonded together
Implementation Method 3
applying a force between the first substrate and the second substrate to compress the multiple bump bonds to the same thickness as the thickness of the at least one pillar
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.