Deposition Rate and Gap Filling Characteristics in Cu Chemical Vapor Deposition with Trimethylvinylsilyl Hexafluoro-acetylacetonate Copper (I)

Abstract

To obtain a low-resistivity material and good gap-filling characteristics in the interconnect metallization process for advanced ULSI devices, we investigated the deposition rate and gap-filling characteristics of Cu chemical vapor deposition. We used trimethylvinylsilyl hexafluoro-acetylacetonate copper (I) as the source at deposition temperatures from 150 to 240°C and source partial pressures (Ps) from 16 to 270 Pa. The deposition rate was studied as functions of the deposition temperature and Ps. The deposition rate increased as the temperature increased, but gap filling simultaneously deteriorated under constant Ps. To obtain good gap filling, Ps should be increased, but Ps is restricted by the saturated vapor pressure. Interpretations are given for gap-filling characteristics from the viewpoint of the deposition mechanism. It is concluded that the maximum deposition rate with excellent gap filling is regulated by the source vapor pressure. We succeeded in satisfactorily filling a hole of an aspect ratio of 5.5 at 200 Pa of Ps and at 170°C with the deposition rate of 40 nm/min. To obtain the same hole filling characteristic at a deposition temperature of 180°C, Ps should be raised to 250 Pa and the deposition rate should be 60 nm/min.