Electroplating Processes

1. Seedless Copper Metallization Commercial Si Wafers

The miniaturization of ULSI design below 32 nm required new strategy to copper interconnects metallization in the microelectronics industry. Alternative approach was developed by CAE for seedless copper metallization on the Ta barrier being initially covered in pristine passive oxide layer. The proposed method is provided Ta oxide reduction prevented its re-oxidation and copper deposition from the single electro-chemical bath. Cu electrodeposition includes 2 steps: 1st) Ta oxide removing from theTa barrier layer by the electrochemical reduction; 2d) copper electroplating on Ta from pyrophosphate electrolyte. This method is a generic one and may also be applied to other passivated metals and alloys (Ru and Ru/Ta mixed metals), being currently considered as barrier films for future seedless integrated systems.

Schematic visualization of the copper electroplating over Ta

Two regions represent Cu deposition procedure over Ta as function
of applied potentials:1st.Ta oxide reduction ; 2d. Cu electroplating

Cu filling 22 nm trenches over TaN/Ta barrier formed on the commercial Si wafers


2. High temperature solar absorptive coatings

A solar absorptive coating accumulated solar energy by receiver of the solar power tower has a temperature limit, its efficiency is reduced with operation time in air at elevated temperatures >600°C.
The solar absorptive coatings with thermal corrosion resistance during long term operation in air at 700°C based on electrophoretic deposition ( EPD) the composite materials was developed by CAE.
The EPD proceeds via three processes, particle charging, particle transport via a voltage difference, and particles deposition via neutralization.
A new developed solar absorptive coating provides exceptional optical absorptivity and high resistance to thermal oxidation in air at temperatures above 700°C. Solar absorptive coating was electrodeposited on the Inconel 625 alloy substrate from suspension containing the micronized metal oxide powders, glass frit and polysiloxane binder . Upon heat treatment of the composite coating melted glass frit formed a glass matrix which protected the alloy surface from high temperature oxidation and sealed micro cracks formed during thermal oxidative stress. Developed composite coating provides high optical absorptivity ~ 95-96% in a wide range of solar spectrum and thermal stability at exposition at 750°C in air atmosphere during aging test.

Solar absorptive coatings sprayed &
EP deposited on the Inconel alloy

Inconel tube & flat specimens with
high temperature solar absorptive coating

Similar absorptivity was obtained on Inconel alloy covered by high temperature solar absorptive coating after aging test performed at 750°C during 1145hrs in air