| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Friday Sessions |
| Session PS1-FrM |
| Session: | Plasma-Surface Interactions in Materials Processing II |
| Presenter: | J. Chung, Tohoku University, Japan |
| Authors: | J. Chung, Tohoku University, Japan S. Yasuhara, Tohoku University, Japan K. Tajima, Semiconductor Technology Academic Research Center, Japan H. Yano, Semiconductor Technology Academic Research Center, Japan S. Kadomura, Semiconductor Technology Academic Research Center, Japan M. Yoshimaru, Semiconductor Technology Academic Research Center, Japan N. Matsunaga, Semiconductor Technology Academic Research Center, Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
While the feature size of ultra-large-scale integrated circuits (ULSIs) has been shrinking, conventional Al/SiO2 interconnects have been substituted by Cu/low-dielectric (low-k) film interconnects to reduce the resistance-capacitance (RC) delay and power consumption of the circuits . Since suitable Cu etching processes are not readily available, damascene processes have been developed for Cu/low-k interconnects. Plasma processes are extensively used for the etching of low-k films. However, since low-k films, such as porous silica films incorporated with methyl groups (SiOC films), are vulnerable to plasma irradiation, low-k films are severely damaged during plasma etching processes. During such processes, methyl groups are extracted from SiOC films due to ion, radical, and photon irradiation from plasma. As a result, the dielectric constant of SiOC films increases during plasma etching processes. We previously proposed a neutral beam process, in which the effects of photon irradiation from plasma can be eliminated, and using this process, we achieved low-damage etching/ashing of low-k films, which is not possible with the conventional plasma process. We speculated that the elimination of photon irradiation was attributed to the low-damage etching of low-k films. Still, the damage mechanism in low-k films during plasma etching has not been fully clarified. Further experiments are therefore needed to fully understand the degradation mechanism of structure and k value of low-k film and influences of ion, radical, and/or photon irradiation on the structure and k value of low-k film during the plasma etching processes. For these reasons, we precisely investigated the changes of structure (linear Si-O, Cage Si-O, Network Si-O, Si-CH3/Si-O, Si-(CH3)1/Si-(CH3)1 ,and k value by ions, chemical reactions by radicals and ions, and photon irradiation on SiOC films during Ar, CF4, O2 and H2 plasma irradiation. We found that the damage degree of low-k film depends on its structure components ratio.