Reliability Characteristics of W/WN/TaO[sub x]N[sub y]/SiO[sub 2]/Si Metal Oxide Semiconductor Capacitors

Abstract

We investigated the effects of post-gate anneal and WN sputtering power on the gate dielectric integrity of W/WN/TaO x N y /SiO 2 /Si metal oxide semiconductor ͑MOS͒ capacitors. The process damage induced by physical vapor deposited metal gates in the high-permittivity ͑k͒ gate dielectric was partially relieved by a post-gate anneal. This is manifested by reduced leakage current, higher wear-out breakdown voltage, reduced charge trapping, and improved interface characteristics such as reduced hysteresis and interface state density (D it ). We observed a noticeable increase of charge trapping and interfacial roughness at the WN/TaO x N y interface with WN power density while the D it level remained similar. Degradation in the reliability characteristics with sputtering power density might be attributed to irrecoverable damage in the TaO x N y film.With shrinking of complementary metal oxide semiconductor ͑CMOS͒ device dimensions to the sub-0.1 m regime, the vertical dimension of SiO 2 is also being scaled down to less than 20 Å in order to obtain the high device performance and to suppress short channel effects. In this regime of SiO 2 thickness, however, the large gate leakage current due to direct tunneling will increase static power consumption and affect circuit operation. 1 Several highpermittivity ͑k͒ dielectrics have been widely studied to prevent the problems caused by the large gate current. 2-5 Especially, direct metal gate on high-k gate dielectric has attracted a lot of attention because of low resistance in narrow gate lines and no gate depletion that allows the metal/high-k gate stack to have smaller capacitance equivalent thickness ͑CET͒. Since some metals have chemical and thermal instability with dielectrics at elevated temperatures, selection of a stable metal gate on the high-k dielectric is a prerequisite for device application. For instance, the TiN/SiO 2 interface is stable up to 850°C, while the WN/SiO 2 interface becomes unstable over 650°C. 6 TiN unfortunately has chemical reaction with Ta 2 O 5 at temperatures higher than 750°C, resulting in an increase of leakage current. 7 WN gate electrode on Ta 2 O 5 shows better thermal stability and lower leakage current. 8 Other issues of direct metal gates are the metal penetration and plasma damage into the SiO 2 when prepared by the physical vapor deposition ͑PVD͒ method. The damage which is more severe for higher energy sputtering 9 leads to the degradation of reliability, interface, and bulk properties of SiO 2 /Si MOS system; 10-12 however, PVD metal gate on the high-k gate dielectric in terms of process-induced damage has not yet been reported.In this study, we report an in-depth study of sputtered W/WN metal gate on the TaO x N y /SiO 2 gate dielectric, i.e., the effects of post-gate anneal and sputtering power density during WN deposition on the reliability of the high-k gate dielectric. ExperimentalFor the evaluation of PVD metal gate on the high-k gate dielectric, W/WN/TaO x N y /SiO 2 /Si metal oxide semiconductor ͑MOS͒ capacitors were ...

Improved Electrochemical Performance of the 5 V Spinel Cathode LiMn[sub 1.5]Ni[sub 0.42]Zn[sub 0.08]O[sub 4] by Surface Modification

“…[13][14][15][16] Also, the coating materials for the 5 V spinels are limited to ZnO [13][14][15] and Bi 2 O 3 , 16 thus far. Al 2 O 3 is regarded as an excellent coating material for 4 V cathodes, [25][26][27][28] but to our knowledge, the surface modification of the 5 V spinel cathodes with Al 2 O 3 has not been explored.…”

An exploratory analysis: extracting materials science knowledge from unstructured scholarly data

“…To further analyze two different approaches, the sample abstract (Cho et al , 2002) described in Figure 5 was used as an input document to demonstrate different outputs from HIVE-4-MAT and MatScholar.…”

Thermal Stability and Electrical Characteristics of Tungsten Nitride Gates in Metal–Oxide–Semiconductor Devices

“…[7][8][9][10] Moreover, there are also some reports on the electrical characteristics and reliability of MOS devices with tungsten nitride gates. [11][12][13][14] An obvious phenomenon of nitrogen desorption from tungsten nitride films was noticed. However, electrical effects of nitrogen desorption in previous studies were not thoroughly explored.…”