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P: Fachverband Plasmaphysik

P 10: Poster: Plasmatechnologie

P 10.12: Poster

Dienstag, 31. März 2009, 17:30–19:30, Foyer des IfP

Plasma Etching of High-k Dielectric HfO2 Films for Technological Applications — •Harald Richter, Mirko Fraschke, Mindaugas Lukosius, Christian Wenger, Dirk Wolansky, Jürgen Berthold, Steffen Marschmeyer, and Ioan Costina — IHP Frankfurt, Im Technologiepark 25, 15236 Frankfurt (Oder)

The integration of novel CMOS compatible materials is going to play an important role in semiconductor industry. Materials with higher k values are of essential interest for gate isolators or capacitor dielectrics in advanced technologies. Using high-k material HfO2 integrated passive MIM (metal-insulator-metal) capacities can be increased essentially. This work is dedicated to plasma etching of MIM stack TiN/HfO2. In contrast to other studies using high temperatures (up to 350°C), HfO2 plasma etching was realized by magnetically enhanced reactive ion etching at conventional cathode and wall temperatures of 60°C. For plasma etching of capacitor layers a two-stage process was developed. First, the upper TiN electrode was etched in HBr reaching selectivities to underlying HfO2 up to 15:1. Afterwards, BCl3 containing plasma is used to etch HfO2 with acceptable etch rates and sufficient selectivity realizing critical etch stop at lower TiN electrode. Process control is based on optical emission spectroscopy detecting 273nm wavelength. Surface analysis of etched HfO2 films supports thermodynamical predictions of plasma reactions between Boron and HfO2. In comparison to capacitors using classical dielectric Si3N4, the successful integration of HfO2 into a quarter-micron BiCMOS technology leads to almost three times higher MIM area capacities.