Effect of Nitridation on Low-Frequency (1/f) Noise in n- and p-MOSFETS with HFO[sub 2] Gate Dielectrics

Abstract

The nitridation effects on low-frequency ͑1/f͒ noise in metallorganic chemical vapor deposited HfO 2 n-and p-metal oxide semiconductor field effect transistors ͑MOSFETs͒ are reported. Devices with a postdeposition anneal ͑PDA͒, performed after HfO 2 deposition, in a N 2 or NH 3 ambient were investigated. A significant variation in noise was observed when different PDAs were employed. Devices annealed with N 2 showed lower input referred noise S VG ͑ϳ125 V 2 /Hz͒ for ͉V G -V T ͉ ϳ 0.1 V, close to the ITRS specifications when compared to NH 3 anneals ͑ϳ1100 V 2 /Hz͒. Carrier trapping is shown to be the origin of the 1/f fluctuations for most n-MOSFET process splits. For p-MOSFETs, no significant impact of the PDA was observed, yielding a constant S VG ͑ϳ200 V 2 /Hz͒. Additionally, two types of interfacial layers were considered for n-MOSFETs, i.e., nitrided and non-nitrided interfaces, prepared by a decoupled plasma nitridation before HfO 2 deposition. Different trap density profiles were derived from the noise spectra for the nitrided-and non-nitrided-interface n-MOSFETs. This suggests that nitridation can induce nitrogen-related defects which lead to a variation in the concentration of oxygen vacancies in the bulk HfO 2 . The binding configuration between the atoms may also play an important role.

Comparison oF Electrical Measurements with Structural Analysis oF Thin High-k Hafnium-based Films

“…Using the conductance method, as before, the value of D it was calculated for the two forming gas annealed samples and the results are presented in table II. The obtained values (in the range of few 10 11 cm -2 ) are consistent with the values previously reported on similar samples that have undergone both DPN and FGA (10). The presence of nitrogen reduces the effectiveness of Si/SiO 2 interface passivation, so as the values of D it for these samples are higher than the ones expected for a Si/SiO 2 interface after FGA (~10 10 cm -2 ).…”

“…Although this value is quite high, it is consistent with the values reported in the literature from other groups on as-grown high-k dielectric films (7,8). However, it has been found that using a forming gas anneal at the end of the fabrication process, the value of D it can be reduced to as low as ~10 10 cm -2 (2,5,6,(9)(10)(11). This is due to the fact that hydrogen passivates effectively the interface between the Si substrate and the thin SiO 2 film underneath the Hf-based film, thus reducing the number of interface states.…”

Assessment of temperature dependence of the low frequency noise in unstrained and strained FinFETs

“…One can note that the nitridation of the hafnium oxide prevents the penetration of dopants in the oxide. This has been proven in previous observations in planar transistors [7]. examples of the frequency normalized noise spectral density versus temperature behavior for a p and n-channel device.…”

(Invited) Degradation in MOSFET Multistack High-k Gate Dielectrics Due to Hot Carrier and Constant Voltage Stress

“…Some of the reasons for these discrepancies are higher trap density (6), interfaces between multilayer gate stacks (7) and nonuniform spatial (8) and energy (9) distribution of the high-k gate oxide traps compared to the conventional, native gate oxide.…”