AVS 51st International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS1+DI-FrM

Paper PS1+DI-FrM9
Selective Etching of HfO@sub 2@ High-k Dielectric over Si in C@sub 4@F@sub 8@/Ar/H@sub 2@ Inductively Coupled Plasmas

Friday, November 19, 2004, 11:00 am, Room 213A

Session: High K and Difficult Materials Etch
Presenter: K. Takahashi, Kyoto University, Japan
Authors: K. Takahashi, Kyoto University, Japan
K. Ono, Kyoto University, Japan
Y. Setsuhara, Kyoto University, Japan
Correspondent: Click to Email
As integrated circuit device dimensions continue to be scaled down, increasingly strict requirements are being imposed on plasma etching technology. Regarding gate dielectrics, the technological challenge continues for growing ultrathin SiO@sub 2@ films of high quality; however, the ultimate solution relies on high dielectric constant (k) materials. In integrating high-k materials into device fabrication, an understanding of the etching characteristics of the materials is required for their removal and for contact etching. This paper presents the etch rates and possible etch mechanisms for HfO@sub 2@ thin films on Si substrate in inductively coupled plasmas containing mixtures of CF@sub 4@/Ar/H@sub 2@ and C@sub 4@F@sub 8@/Ar/H@sub 2@, as a function of gas composition and rf bias power. In the experiments, the discharge was established at a gas pressure of 20 mTorr and an rf source power of 280 W. The gas flow rates of fluorocarbon and Ar were 2.5 and 247.5 sccm (the ratio of fluorocarbon to total was 1 %). The rate of H@sub 2@ was varied between 0 and 16 sccm. As the dc selfbias voltage was maintained at the constant value of -90 V, HfO@sub 2@ and Si were etched in the CF@sub 4@/Ar/H@sub 2@ plasma with no relation to H@sub 2@ flow rate. In the C@sub 4@F@sub 8@/Ar/H@sub 2@ plasma, however, the conditions could be found where HfO@sub 2@ was etched at the rate more than 10 nm/min, and the fluorocarbon polymer deposited on Si. In this regime, it can be possible to selectively etch HfO@sub 2@ over Si. The chemical composition of the polymer was carbon-rich, and the carbon content on HfO@sub 2@ was not so much as on the polymer. It can be said that carbonized products may correspond to etch products for HfO@sub 2@. @FootnoteText@ This work was supported by NEDO/MIRAI Project.