Electroless Deposition for Pad Metallization: Xenolyte

The Xenolyte portfolio includes cleaning and activation pre-treatment solutions and plating chemistries for the electroless deposition of nickel, palladium and gold in pad metallization technologies. Xenolyte products are used as the under bump metallization (UBM) for the connection to solder balls, wire bonds, and wedge bonds. The Xenolyte nickel, palladium and gold process provides a corrosion protection layer for the underlaying interconnects and solder joint connection to the IC substrate.

The nickel layer serves as the diffusion barrier and provides protection against the formation of Kirkendall voids. The palladium and gold depositions provide adhesion for the soldering and bonding, as well as protection against oxidation.

The Xenolyte electroless UBM process is compatible with aluminum and copper pads, with specialized pre-treatments for each. Xenolyte has demonstrated compatibility with standard aluminum and gold bonding, as well as emerging copper wire bonding technology.

Features and Benefits

The industry requirements for UBM include a robust and stable connection, with low resistance, to the IC substrate. With Xenolyte's proven technologies, the following process and deposition requirements are satisfied at significantly lower costs compared to traditional sputtering technology.

• Enhanced adhesion between UBM and IC substrate
• Robust bond pad for wire bonding
• Stress minimized metal stack
• Improved reliability with pure palladium for wire bonding technology
• Process flexibility for use with aluminum, gold, and copper wire bonding technologies

To address the semiconductor industry's requirements for green technology solutions, Atotech has developed innovative products for UBM applications. Xenolyte lead-free nickel and cyanide-free gold enable customers to implement environmentally responsible production solutions.