Flip-Chip Alignment Structures for Quantum Chip Separation Control
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Solution Overview
Problem
Existing processes for fabricating 3D integrated circuit devices do not allow for precise control of chip separation, orientation, and alignment, limiting flexibility and component density in qubit chip design.
Innovation Solution
A method involving etching substrates to form raised and recessed alignment structures with specific trapezium-shaped cross-sections, allowing precise alignment and bonding through flip-chip bumps or indium film, with restricted movement along axes, and forming quantum circuit components like qubits and through-substrate vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing flip chip processes are used for 3D integrated circuit fabrication, then chip stacking and component density are achieved, but precise control of chip separation, orientation, and alignment is lost
Solution Approach 1:
The patent applies preliminary action by pre-forming raised alignment structures on one substrate and corresponding recessed alignment structures on the other substrate before the bonding process. These structures are etched into the substrates in advance, creating predetermined geometric features that will automatically guide and constrain the relative positioning of the substrates during bonding, thereby achieving precise alignment control before the actual assembly occurs.
Solution Approach 2:
The patent uses the raised and recessed alignment structures as intermediary elements that mediate the alignment between two substrates. These alignment structures act as physical intermediaries that transmit and enforce the desired relative positioning, orientation, and separation distance between substrates during the bonding process, eliminating the need for complex external alignment control systems.
2Manufacturing precision
If passive alignment apparatus with recesses and projections are used, then some alignment is achieved, but precise control of separation distance and orientation is still limited
Solution Approach 1:
The patent applies local quality by creating alignment structures with specific local geometric properties (raised portions on one substrate, recessed portions on the other) that are tailored to control specific parameters such as separation distance and orientation. The trapezium-shaped cross-sections with specifically engineered angles and dimensions provide localized control over the bonding interface, enabling precise separation distance control while maintaining process simplicity through direct integration into the substrates.
3Manufacturing precision
If substrates are bonded directly without alignment structures, then manufacturing process is simple, but chip separation and alignment control is poor
Solution Approach 1:
The patent applies the nested doll principle by having the raised alignment structure on one substrate fit into the recessed alignment structure on the other substrate during bonding. This nesting arrangement creates a hierarchical structure where the alignment features are integrated within the substrate structures themselves, providing precise relative orientation control while minimizing overall device complexity through self-contained alignment mechanisms.
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 precise control of chip separation and alignment, enhancing flexibility and component density in qubit chip design, facilitating the fabrication of advanced quantum circuits.
Implementation Method 1
Bonding the first substrate to the second substrate may comprise thermocompression bonding
Implementation Method 2
depositing at least one of: a plurality of flip-chip bumps on at least one of the first surface of the first substrate or first surface of the second substrate
Data Source
Figure 1
Figure 2A~2D
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AI summary
The invention relates to the field of chip fabrication, in particular to the fabrication of superconducting integrated circuits for use in quantum computers. Raised and recessed alignment structures are provided on the surfaces of two substrate such that the raised and recessed alignment structure extends within the recessed alignment structure to a maximum depth determined by the geometry of the alignment structures. The alignment structures act as a hard stop for positioning and aligning the substrates for flip chip bonding.