ICMCTF2005 Session B4: Ion Beam Technologies

Dry etching with reactive plasma has been widely used in the fabrication of semiconductor devices. In the view of the development of integrated semiconductor devices, more precise control of the etching process is required for further progress. It has been known that reactive ion species and reactive neutral species, which are produced in plasma, play a great role in etching reactions. However, the mechanism for the etching reaction has not yet been quantitatively described. It is necessary to clarify the roles of individual reactive ion bombardments and neutral species. A beam experimental method is very useful tool for investigation of interaction of individual species with surfaces. We have developed a mass analyzed low-energy ion beam and molecular beam system to investigate an interaction of reactive ion and neutral species with surfaces. As advanced high-k gate dielectrics, such as HfO₂, are being developed to replace SiO₂ in the near future generation of microelectronics devices, understanding their plasma etch characteristics becomes vital for introducing the new materials into the manufacturing process. We studies on the interactions of HfO₂ with Cl⁺, BCl_x+ (X = 1, 2) and SiCl _x⁺ (X = 1, 2, 3), using the mass-analyzed ion beam apparatus. Etching yields increase with increasing number of chlorine atoms contained in the incident ions, and etching products are hafnium chlorides. The kinetic energy of etching products was larger than 0.1 eV. Therefore, products are different from thermally desorbed molecules. This indicates that desorption is caused by the momentum transfer to hafnium chloride.

This work was supported by NEDO.