Nitrided Tetragonal $\hbox{ZrO}_{2}$ as the Charge-Trapping Layer for Nonvolatile Memory Application

Abstract

Employment of a tetragonal ZrO 2 film as the chargetrapping layer for nonvolatile memory was investigated and the NH 3 nitridation effect of the ZrO 2 film on memory performance was also explored in this letter. The permittivity of the tetragonal ZrO 2 film is slightly reduced from 38.7 to 36.9 after nitridation; nevertheless, nitridation introduces more trapping sites and passivates the grain boundary channel which results in a high operation speed in terms of 2.6-V flatband voltage shift by programming at +10 V for 10 ms and a good retention characteristic with 20.2% charge loss after ten-year operation at 125 • C, both are superior to that without NH 3 nitridation. Most importantly, the process is fully compatible with existent ULSI technology and paves the way to adopt a high-permittivity crystalline dielectric as the charge-trapping layer for future high-performance nonvolatile memory.

Defect states and charge trapping characteristics of HfO2 films for high performance nonvolatile memory applications

“…To solve these problems in SONOS type CTF memory, CTF memory devices using high-k materials such as HfO 2 , Al 2 O 3 , ZrO 2 , etc., have been developed in recent years. [9][10][11][12][13][14][15] These devices can provide large band offset with respect to Si, high trap density, and small equivalent oxide thickness (EOT). Therefore, the CTF memory device with high-k film is expected to offer better device performance as compared to the conventional CTF device with Si 3 N 4 film.…”

Charge-trapping characteristics of fluorinated thin ZrO2 film for nonvolatile memory applications

“…[2][3][4] On the other hand, ZrO 2 shows similar dielectric properties as HfO 2 but has higher k value ($37). 5 Consequently, there is an increasing interest in exploring ZrO 2 as CTL. 5,6 Wu et al studied the charge-trapping characteristics of ZrO 2 with and without nitridation and found that MONOS device with nitrided ZrO 2 showed better performance than that without nitridation due to nitrogen passivation of the ZrO 2 film.…”

“…5,6 Wu et al studied the charge-trapping characteristics of ZrO 2 with and without nitridation and found that MONOS device with nitrided ZrO 2 showed better performance than that without nitridation due to nitrogen passivation of the ZrO 2 film. 5 Besides nitrogen, fluorine is also an excellent passivant to remove oxide defects and strengthen the dielectric films due to its very high electronegativity. 9 Therefore, fluorination is an effective way to improve the charge-trapping characteristics of dielectrics.…”

(ZrO2)x(La2O3)1-x Alloy as High-k Gate Dielectric for Advanced CMOS Devices

“…Worth to be mentioned is that insignificant leakage current change can be obtained after RTA. The leakage current of annealed samples is much lower than that reported in [3] and it can be ascribed to the amorphous phase of the (ZrO 2 ) x (La 2 O 3 ) 1-x alloy which does not have grain boundary induced leaky paths as a crystalline dielectric [6][7].…”