Conductive Seed Layer Deposition for Precise Wafer Interconnect Printing
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Solution Overview
Problem
Current metal additive manufacturing techniques, such as selective laser melting (SLM) and electron beam melting (EBM), are limited by high costs and result in rough surface finishes due to unmelted metal powder, while electrochemical additive manufacturing faces challenges in achieving high-quality parts due to variable deposition rates and quality without well-developed feedback control.
Innovation Solution
An electrochemical additive manufacturing method using deposition feedback control, where a cathode and anode array are used in an electrolyte solution, with feedback signals analyzed to adjust process parameters and modify layer descriptions, enabling precise construction of interconnection features like wafer bumps or pillars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrochemical additive manufacturing is used to construct interconnection features, then deposition precision can be improved, but deposition quality becomes variable due to inconsistent seed layer conductivity
Solution Approach 1:
A conductive seed layer is deposited on the substrate before the main interconnection features are constructed. This preliminary action ensures that the substrate has sufficient electrical conductivity to support consistent electrochemical deposition throughout the manufacturing process, thereby improving deposition quality consistency while maintaining precision.
2Ease of manufacture
If traditional metal additive manufacturing (SLM/EBM) is used, then structural parts can be produced, but surface finish becomes rough due to unmelted powder
Solution Approach 1:
The patent replaces thermal-based additive manufacturing (SLM/EBM) with electrochemical additive manufacturing. Instead of using heat and mechanical melting to construct parts, electrochemical reactions are used to deposit material layer by layer. This substitution eliminates the rough surface finish problem caused by unmelted powder while maintaining the ability to produce complex structural parts.
3Manufacturing precision
If photoresist masking is used in conventional wafer bumping, then pattern definition can be achieved, but manufacturing complexity increases due to multiple processing steps
Solution Approach 1:
The patent extracts and eliminates the photoresist masking step from the conventional wafer bumping process. By using electrochemical additive manufacturing with direct digital deposition, pattern definition is achieved through digital control of the deposition process rather than through physical masks. This reduces manufacturing complexity by removing multiple processing steps while maintaining pattern definition accuracy.
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 method allows for the production of high-quality interconnection features with precise control over deposition, overcoming the limitations of traditional methods by ensuring consistent material distribution and quality across the manufacturing process.
Implementation Method 1
anode array, each having a corresponding control circuit configured to control the current flow through the anode. The substrate is placed into contact with an electrolyte solution, and the conductive seed layer on the substrate is aligned with and placed into contact with the anode array
Implementation Method 2
The printhead is immersed in an electrolyte solution, and a current is passed through the printhead to construct the interconnection features layer by 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.