Charge trapping induced frequency-dependence degradation in n-MOSFETs with high-k/metal gate stacks

• Published in: Thin solid films Vol. 520; no. 5; pp. 1511 - 1515
• Main Authors: Dai, Chih-Hao, Chang, Ting-Chang, Chu, Ann-Kuo, Kuo, Yuan-Jui, Hung, Ya-Chi, Lo, Wen-Hung, Ho, Szu-Han, Chen, Ching-En, Shih, Jou-Miao, Chung, Wan-Lin, Chen, Hua-Mao, Dai, Bai-Shan, Tsai, Tsung-Ming, Xia, Guangrui, Cheng, Osbert, Huang, Cheng Tung
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30.12.2011; Elsevier
• Subjects: Applied sciences; Charge; Charge carriers: generation, recombination, lifetime, trapping, mean free paths; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectrics; Diffusion; Dynamics; Electron trapping; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Electronics; Exact sciences and technology; Gates; High-k gate dielectric; Nitrides; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Stresses; Threshold voltage instability; TiN metal gate; Transistors; Trapping; High-k gate dielectric; Electron trapping; TiN metal gate; Threshold voltage instability; Voltage threshold; MOSFET; Frequency dependence; Vacancies; Titanium nitride; Hafnium oxide; Transients; CV characteristic; Charge carrier trapping; Gallium tellurides; Stress effects; Instability; High k dielectric; Reliability; Gates
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.07.027

This letter investigates the reliability issues of HfO 2/Ti 1 − x N x metal-oxide-semiconductor field effect transistor in terms of static and dynamic stress. The results indicate threshold voltage ( V th ) instability under dynamic stress is more serious than that under static stress, owning to transient charge trapping within high-k dielectric. Capacitance–voltage techniques verified that electron trapping under dynamic stress was located in high-k dielectric near the source/drain (S/D) overlap region, rather than the overall dielectric. Furthermore, the V th shift clearly increases with an increase in dynamic stress operation frequency. This phenomenon can be attributed to the fact that electrons injecting to the S/D overlap region have insufficient time to de-trap from high-k dielectric. We further investigated the impact of different Ti 1 − x N x composition of metal-gate electrode on charge trapping characteristics, and observed that V th shift decreases significantly with an increase in the ratio of nitride. This is because the nitride atoms diffusing from the metal gate fill up oxygen vacancies and reduce the concentration of traps in high-k dielectric.