Self-Assembly Circuit Pads With Wettability-Controlled Alignment
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Solution Overview
Problem
Existing self-assembly methods struggle to achieve precise alignment of electronic circuits with conductive pads, especially as pitch and width dimensions decrease, leading to misalignment and poor interconnection, and require complex and expensive robotic alignment systems.
Innovation Solution
A manufacturing method that defines the edges and locations of conductive pads and insulating posts in a single photolithography step, followed by etching and polishing to form assembly sites with controlled wettability differences, enabling precise alignment and hybrid bonding of electronic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If robotic pick-and-place machines are used for alignment, then assembly rate can be maintained, but alignment precision deteriorates due to decreasing dimensions
Solution Approach 1:
The patent replaces the mechanical robotic pick-and-place system with a self-alignment mechanism based on liquid confinement and surface tension. The liquid bridge automatically pulls the die into precise alignment with the wafer through capillary forces, eliminating the need for complex robotic positioning systems while achieving sub-micron alignment accuracy.
Solution Approach 2:
The alignment process is made self-aligning through the liquid bridge mechanism. The die automatically aligns itself to the wafer assembly site through the forces exerted by the confined liquid, without requiring external robotic positioning or complex alignment machinery. The system uses its own liquid confinement mechanism to achieve precise alignment.
2Manufacturing precision
If alignment accuracy is increased to less than 1 μm, then interconnection reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical alignment machines with a simple liquid confinement system. The alignment is achieved through the physical forces of surface tension and capillary action in the liquid bridge, which naturally provide sub-micron precision without requiring expensive robotic positioning systems or complex alignment machinery.
Solution Approach 2:
The liquid bridge serves as an intermediary medium that facilitates precise alignment between the die and wafer. Instead of using complex mechanical positioning systems, the confined liquid acts as a mediator that transmits alignment forces through surface tension and capillary action, achieving high precision with simple equipment.
3Area of moving object
If pitch and width dimensions are decreased, then circuit density improves, but alignment precision deteriorates
Solution Approach 1:
The self-alignment mechanism through liquid confinement automatically adjusts to achieve precise alignment even as pitch and width dimensions decrease. The liquid bridge forces naturally adapt to smaller features, maintaining alignment precision proportional to the feature size without requiring separate alignment systems for different pitch scales.
Solution Approach 2:
The patent changes the alignment mechanism from mechanical positioning to liquid-based self-alignment, where the alignment precision is determined by the physical parameters of the liquid bridge (surface tension, volume, confinement geometry) rather than mechanical tolerances. This allows alignment precision to scale with decreasing pitch and width dimensions.
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
Ensures accurate alignment and bonding of conductive pads between electronic circuits, compatible with conventional manufacturing techniques, and reduces misalignment issues, allowing for smaller feature sizes and improved interconnection reliability.
Implementation Method 1
The electronic circuit to be assembled may be a die (or chip) and correspond to an integrated circuit. The support generally corresponds to another electronic circuit... A method of self-assembly of an electronic circuit on a support may be based on the confinement of a drop of a liquid, for example, water, on a surface having a high wettability (which can be designated as a hydrophilic surface) located on the support and corresponding to the desired location of the electronic circuit.
Implementation Method 2
The forces exerted by the drop on the electronic circuit then displace electronic circuit 200 all the way to the desired alignment relative to the assembly site 110... The wettability of a material may be characterized by the contact angle θ (visible in FIG. 1) of a liquid drop on the material
Data Source
AI summary
The present description relates to a method of manufacturing an electronic circuit (30) comprising:a support (32),an assembly site (31) having a first surface protruding from said support intended to be assembled to an assembly site of another electronic circuit by a self-assembly method; anda peripheral area (39) around said assembly site,the assembly site (31) comprising at least one level, each level comprising conductive pads (34) and insulating posts (380) between the conductive pads,said manufacturing method comprising the forming of said at least one level of the assembly site, such that the edges, in at least one direction (X) of the main plane (XY), of each level of the assembly site and the locations, in the at least one direction (X), of the conductive pads and of the insulating posts of the same level are defined in a same photolithography step of said method.