Multi Metal Stack Pillar
Using the Solstice® Solvent and Wet Etch Chambers
Enabling High-Density Advanced Packaging
As advanced packaging architectures continue to evolve, manufacturers require interconnect technologies capable of supporting higher I/O density, finer pitches, improved reliability, and greater electrical performance.
Multi-metal pillar structures have become a widely adopted solution for advanced packaging applications, combining the electrical conductivity of copper (Cu) with barrier and solderable layers such as nickel (Ni), tin-silver (SnAg), or gold.
Among these, Cu-Ni-SnAg pillar structures have emerged as the industry’s most common configuration for flip-chip and advanced packaging applications.
Multiple Metals, One Automated Process
Successful multi-metal pillar manufacturing requires the precise deposition of several materials in sequence while maintaining uniformity, minimizing contamination, and maximizing throughput.
Key process requirements include:
- Uniform copper pillar formation
- Precise nickel barrier deposition
- Consistent SnAg cap plating
- Automated inter-metal rinsing
- Contamination control
- High throughput and repeatability
Meeting these requirements efficiently requires a tightly integrated process platform.
How ClassOne Enables Multi-Metal Stack Pillars
The Solstice® platform combines multiple electroplating and support processes on a single automated system, allowing manufacturers to create complete multi-metal pillar structures with minimal wafer handling and maximum process control.
Cu-Ni-SnAg Process Flow on Solstice®
Copper Plating
High-uniformity copper pillar formation.
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Automated Inter-Metal Rinsing
Clean wafer transfer between process steps.
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Nickel Plating
Reliable diffusion barrier deposition.
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Automated Inter-Metal Rinsing
Contamination-free process integration.
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SnAg Plating
Uniform solder cap formation.
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Finished Cu-Ni-SnAg Pillar Structure
Ready for downstream assembly.
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Photoresist Strip
Using the Solstice® Solvent Chamber
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UBM Etch
Using the Solstice® Wet Etch Chamber
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From a seed and patterned wafer to a fully metallized wafer, Solstice provides turnkey metallization processing.
Why Solstice®?
The modular Solstice® platform was specifically designed to integrate multiple electroplating and wet process technologies on a common automated system. This flexibility makes it uniquely suited for multi-metal stack applications.
Key Advantages
- Automated Cu-Ni-SnAg processing
- Dedicated chambers and rotors that eliminate bath cross-contamination
- Automated inter-metal wafer rinses
- Vacuum pre-wet (VPW) for challenging structures
- Advanced scheduling for optimized throughput
- Excellent wafer-to-wafer repeatability
- R&D through high-volume manufacturing scalability
Typical Performance
- Within-wafer uniformity: <5%
- Wafer-to-wafer uniformity: <1%
- Void-free fill performance
See Cu-Ni-SnAg Pillar Plating in Action
The video here demonstrates a typical Cu-Ni-SnAg process flow and highlights how Solstice® automates multiple plating and support processes on a common platform to simplify manufacturing and maximize productivity.
Talk to Our Experts
Whether you are developing Cu-Ni-SnAg pillar structures for advanced packaging, AI processors, memory devices, or next-generation semiconductor applications, ClassOne Technology provides the automated electroplating solutions required to simplify process integration and scale manufacturing.
Solstice® Single-Wafer Platform for Advanced Packaging
