AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeM

Paper PS2-WeM2
Etching Characteristics of High-k Dielectric HfO@sub 2@ Films in Inductively Coupled Fluorine-Containing Plasmas

Wednesday, November 5, 2003, 8:40 am, Room 315

Session: Etching Difficult Materials
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, C@sub 4@F@sub 8@/Ar, or SF@sub 6@/Ar, as a function of gas composition, rf bias power, and surface temperature. The discharge was established at a gas pressure of 20 mTorr and an rf source power of 300 W. As the concentration of F-containing gases was decreased, the etch rate of Si decreased owing to the decreased amount of F radicals, while the etch rate of HfO@sub 2@ remained almost unchanged, resulting in an increase in etch selectivity of HfO@sub 2@ over Si. Increasing the bias power increased the etch rates of both Si and HfO@sub 2@; however, the increase in etch rate was more significant for HfO@sub 2@ than for Si, also resulting in an increase in selectivity. These results imply that the etching of HfO@sub 2@ relies primarily on the sputtering by ion bombardment, and the etch rates were typically on the order of 20 nm/min with a selectivity > 1 at large Ar concentrations and high bias powers. A comparison is made with the results of plasma and surface diagnostics, to gain a better understanding of the physics and chemistry underlying the processing, and to achieve higher selectivities. @FootnoteText@ This wark was supported by NEDO/MIRAI Project.