Fabrication of Ge-MOS capacitors with high quality interface by ultra-thin SiO2/GeO2 bi-layer passivation combined with the subsequent SiO2-depositions using magnetron sputtering

Abstract

Ge-MOS capacitors were fabricated by a novel method of ultra-thin SiO 2 /GeO 2 bilayer passivation (BLP) for Ge surface combined with the subsequent SiO 2-depositions using magnetron sputtering. For the Ge-MOS capacitors fabricated by BLP with O 2 , to decrease oxygen content in the subsequent SiO 2 deposition is helpful for improving interface quality. By optimizing process parameters of the Ge surface thermal cleaning, the BLP, and the subsequent SiO 2 deposition, interface states density of 4 10 11 cm-2 eV-1 at around midgap was achieved, which is approximately three times smaller than that of non-passavited Ge-MOS capacitors. On the contrary, for the Ge-MOS capacitors fabricated by BLP without O 2 , interface quality could be improved by an increase in oxygen contents during the subsequent SiO 2 deposition, but the interface quality was worse compared with BLP with O 2 .

Postmetallization annealing effect of TiN-gate Ge metal-oxide-semiconductor capacitor with ultrathin SiO2/GeO2 bilayer passivation

“…Hiroshi Nakashima, 1,a͒ Yoshiaki Iwamura, 2 Keita Sakamoto, 2 The postmetallization annealing ͑PMA͒ effect was investigated for a TiN-gate Ge metaloxide-semiconductor capacitor with an ultrathin SiO 2 / GeO 2 bilayer passivation. PMA at 450°C led to the incorporation of nitrogen atoms into the gate stack.…”

“…2,3 By optimizing this bilayer passivation ͑BLP͒ and subsequent gate-insulator deposition, an interface state density ͑D it ͒ of 4 ϫ 10 11 cm −2 eV −1 was achieved near the midgap despite the very thin thickness ͑1.6 nm͒ of the GeO 2 layer. 2 To apply this BLP to a high-permittivity ͑high-k͒/Ge gate stack, there are two major topics to be addressed. One is high-k film fabrication matched with BLP.…”

“…The details of BLP are given elsewhere. 2,3 After complete volatilization of GeO 2 by vacuum annealing, a 1.0-nm-thick SiO 2 interlayer ͑IL͒ was deposited on the cleaned Ge surface at 350°C using rf magnetron sputtering from a SiO 2 target with the addition of O 2 . Note that a GeO 2 layer grows during the SiO 2 deposition and its thickness is approximately 1.0 nm.…”

The Analysis Of Structure For The Multi-Layered Of Ge/TiO2 Films Prepared By The Differential Prressure Co-Sputtering

“…Figure 2 shows the XPS of 8.8 at.% Ge/TiO 2 multi-layer. The spectrum of as-deposited film has only one peak of Ge 3d at 29.3 eV [4,5], and no other peak corresponding to Ge oxide was observed. On the other hand, the spectrum of annealed film has two broad peaks at 32.5 eV and 37.3 eV in addition to the main peak at 29.3eV.…”

“…On the other hand, the spectrum of annealed film has two broad peaks at 32.5 eV and 37.3 eV in addition to the main peak at 29.3eV. The broad peak at 32.5 eV [4,5] and 37.5 eV [6] correspond to Ge oxide such as GeO 2 , and Ti 3p, respectively. Even if oxidations of Ge were occurred in the thin film by annealing, it was very small.…”