Electrochemical Wafer Interconnect Deposition With Feedback Control
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Solution Overview
Problem
Current metal additive manufacturing techniques, such as selective laser melting and electron beam melting, are limited by high costs and result in rough surface finishes due to the thermal fusion of powdered metals, while electrochemical additive manufacturing faces challenges in achieving high-quality parts due to variability in deposition rate and quality across time and location, requiring improved control methods.
Innovation Solution
The implementation of a closed-loop feedback control system in electrochemical additive manufacturing that monitors deposition throughout the process and adjusts manufacturing parameters, using a cathode and anode array in an electrolyte solution to deposit material onto a substrate, allowing for precise control of layer formation and interconnection feature creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrochemical additive manufacturing is used to deposit material onto a substrate, then material deposition occurs, but the deposition rate and quality vary across time and location
Solution Approach 1:
The patent implements a feedback control system that continuously monitors deposition current and uses this information to adjust manufacturing parameters in real-time. The system measures the current flowing through the electrolyte solution and uses this feedback signal to maintain consistent deposition quality and rate across different locations and time periods, resolving the variability issue inherent in electrochemical additive manufacturing.
Solution Approach 2:
The patent dynamically adjusts electrochemical parameters such as current density, voltage, and deposition time based on real-time monitoring data. By changing these parameters adaptively rather than using fixed settings, the system compensates for variations in deposition conditions and maintains consistent material deposition quality throughout the manufacturing process.
2Productivity
If selective laser melting or electron beam melting is used for metal additive manufacturing, then metal parts are produced, but the cost is high
Solution Approach 1:
The patent replaces thermal-based manufacturing systems (laser melting, electron beam melting) with an electrochemical deposition system. Instead of using high-energy beams to melt and fuse metal powder, the system uses electrochemical reactions to deposit metal ions onto the substrate, thereby eliminating the need for expensive laser or electron beam equipment while maintaining metal additive manufacturing capabilities.
Solution Approach 2:
The patent changes the fundamental manufacturing parameter from thermal energy input to electrochemical current input. By using electrical current to drive metal ion deposition instead of thermal melting, the system achieves comparable metal part production at lower cost, as electrochemical equipment is significantly less expensive than selective laser melting or electron beam melting systems.
3Productivity
If powdered metals are thermally fused together to produce a part, then metal parts are manufactured, but the surface finish is rough
Solution Approach 1:
The patent replaces the thermal fusion process with electrochemical deposition. Instead of melting and fusing metal powder particles which leaves unmelted powder on the surface, the system deposits metal ions layer-by-layer through electrochemical reduction, producing a smooth, continuous metal surface without the roughness characteristic of thermally fused powder.
Solution Approach 2:
The patent utilizes the electrochemical phase transition of metal ions from dissolved state to solid metal deposition. This phase change process occurs uniformly at the substrate surface, creating a smooth deposit, whereas thermal melting involves complex phase transitions of powder particles that result in surface roughness from sintered and unmelted material.
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 enables the production of high-quality parts with improved surface finish and precision, overcoming the limitations of traditional metal additive manufacturing methods by ensuring consistent deposition quality and allowing for the creation of complex interconnection features like wafer bumps and pillars.
Implementation Method 1
energizing the anode causing charge to flow through the anode. This creates an electrochemical reduction reaction to occur at the substrate near the anode and deposition of material on the substrate
Implementation Method 2
One or more feedback signals may be measured across the anode array, and these signals may be analyzed to generate a deposition analysis that indicates the extent to which deposition has progressed at locations within the layer
Data Source
AI summary
A system and method of using electrochemical additive manufacturing to add interconnection features, such as wafer bumps or pillars, or similar structures like heatsinks, to a plate such as a silicon wafer. The plate may be coupled to a cathode, and material for the features may be deposited onto the plate by transmitting current from an anode array through an electrolyte to the cathode. Position actuators and sensors may control the position and orientation of the plate and the anode array to place features in precise positions. Use of electrochemical additive manufacturing may enable construction of features that cannot be created using current photoresist-based methods. For example, pillars may be taller and more closely spaced, with heights of 200 μm or more, diameters of 10 μm or below, and inter-pillar spacing below 20 μm. Features may also extend horizontally instead of only vertically, enabling routing of interconnections to desired locations.