Catalytic Forming Gas Anneal on III-V/Ge MOS systems
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1194-A07-06
Catalytic Forming Gas Anneal on III-V/Ge MOS systems Wei-E Wang1, H.-C. Lin1, G. Brammertz1, A. Delabie1, S. Sioncke1, E. Simoen1, M. Caymax1, M. Meuris1, and M. Heyns1 1
IMEC, Kapeldreef 75, 3001 Leuven, Belgium,
ABSTRACT Catalytic-FGA, a combination of the standard forming gas anneal with a catalytic metal gate, has been applied to study the hydrogen passivation of III-V/Ge MOS systems. Pd (or Pt) metal gate catalytically dissociates molecular hydrogen into atomic hydrogen atoms, which then diffuse through the dielectric layer and neutralize certain semiconductor/dielectric interfacial defects. MOS systems with various interfacial qualities, including lattice-matched (n/p) In0.53Ga0.47As/10nm ALD-Al2O3 (or ZrO2)/Pd capacitors, an undoped Ge/~1nm GeO2/4nm ALD-Al2O3/Pt capacitor, and an nGe/8nm ALD-Al2O3/Pt capacitor are fabricated to evaluate the effectiveness of C-FGA. INTRODUCTION Due to the highly reactive and amphoteric nature, hydrogen can play a significant role in altering the electrical properties of its host materials [1]. The beneficial effect of molecular or atomic hydrogen anneal on the electrical performance of Si MOS systems is well documented [2,3], even though hydrogenated species release at the interface has also been linked to the negative-bias temperature instability NBTI issue for p-MOSFETs [4]. Hydrogen passivation on III-V systems has been studied extensively as well, but with less conclusive results [5,6]. For example, Pearton [7] reported that the atomic hydrogen anneal is quite effective in passivating deep donors of GaAs and yet molecular hydrogen anneal is not. However, Chang and Coleman [8] reported that the molecular hydrogen anneal did improve their GaAs MOS device performance. Results about hydrogen passivation on Ge MOS systems are far from conclusive. Afanas’ev et al. showed that interfacial traps and dangling-bond defects at (100)Ge/HfO2 interface are very resistant to hydrogen passivation [9]. Weber et al. claimed that passivation of germanium danglingbonds by hydrogen passivation would simply be ineffective because the interstitial hydrogen is stable exclusively in the negative charge state [10]. Then again, Matsubara et al. recently showed that an atomic hydrogen anneal before the metal gate formation is effective in passivating Ge/GeO2 interface states [11]. Bellenger et al. also reported similar hydrogen passivation benefits on (n/p)Ge/~1nm GeO2/9nm Al2O3/Pt capacitors using the technique to be described below [12]. Atomic hydrogen can be generated in many ways [13]. A simple technique is by depositing a metallic catalyst in the platinum group, such as Pd and Pt, which can dissociate molecular hydrogen into atomic during a standard forming gas anneal [14,15]. The effect of atomic hydrogen on III-V-platinum group metal contacts is also well documented [16]. The same atomic hydrogen effect on the III-V (and Ge) MOS capacitors using platinum group as metal gate, on the other hand, is much less known and
is the focus of this study. This method, though widely utili
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