1-2hit |
Takashi YAMAMOTO Yukiko IZUMI Naoyuki SUGIYAMA Kazuhiro YOSHIKAWA Hideki HASHIMOTO Yoshihiro SUGITA
We prepared HfO2 films by atomic layer deposition (ALD) on three kinds of silicon substrate surfaces (chemical oxide, HF-last surface and thermal oxide), and characterized their morphologies, structures, compositions, and crystallinities by physical analysis. The results revealed that the as-deposited HfO2 films consisted of nano-crystalline particles with a different crystalline system from that of the annealed films. The size of the nano-crystalline particles on the film on the chemical oxide was smaller than those on the other surfaces. The reason is thought to be the difference in OH concentration on the substrate surface. The predominant crystalline phases of all HfO2 films were monoclinic after annealing. Moreover, the film prepared on the chemical oxide had the smoothest surface after annealing. However, island structures with grain boundaries developed in the films on the other surfaces.
Yusuke MORISAKI Takayuki AOYAMA Yoshihiro SUGITA Kiyoshi IRINO Toshihiro SUGII Tomoji NAKAMURA
The characteristics of HfO2 gate stacks, which consisted of the SiN layer deposited between the HfO2 and poly-Si gate electrode and the SiON interfacial layer were investigated. The SiN layer played important role to reduce the leakage current caused by the defect of the crystallized HfO2. The SiN layer was also effective to achieve the prevention of the interfacial reaction, the suppression of dopant penetration. Furthermore, that stack structure indicated excellent TDDB reliability fabricated by conventional high temperature processes.