• Knaut, Martin
• Trommer, Jens
• Mikolajick, Thomas
• Sharma, Saurabh
• Mauersberger, Tom
• Pohl, Darius
• Rellinghaus, Bernd
• Heinzig, André

Abstract

The integration of new materials such as high-k dielectrics or metals into advanced CMOS gate stacks has led to major developments in plasma etching. The authors present a study which is dedicated to the etching of amorphous hafnium zirconium oxide (HZO) and titanium nitride (TiN) layers with Ar/Cl2 chemistry in one single step. By adjusting the gas ratio and the inductively coupled plasma power, the etching process is shown to have a slow and well controllable etch rate for HZO and TiN. Additionally, a high selectivity between both materials and SiO2 can be achieved. Gate stack etching was successfully demonstrated and transmission electron microscopy-images revealed good anisotropic etching for HZO and TiN with an etch stop in SiO2 without damaging the silicon underneath. The process is further applied for the fabrication of metal-ferroelectric-metal capacitors, here TiN-HZO-TiN, and the feasibility of the chosen material combination is proven by electrical characterization. The strategy of using low temperature plasma-enhanced atomic layer deposition for TiN-deposition and forming gas anneal after structuring leads to high remanent polarization-values.

Topics

• impedance spectroscopy
• amorphous
• zirconium
• nitride
• anisotropic
• transmission electron microscopy
• Silicon
• titanium
• forming
• tin
• hafnium
• atomic layer deposition
• plasma etching