Interface Characterization of HfO2/GaSb MOS Capacitors With Ultrathin Equivalent Oxide Thickness by Using Hydrogen Plasma Treatment

• Published in: IEEE transactions on electron devices Vol. 63; no. 9; pp. 3459 - 3465
• Main Authors: Ming-Li Tsai, Jun-Yu Ko, Shin-Yuan Wang, Chao-Hsin Chien
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitor; dielectric interface; equivalent oxide thickness (EOT); Etching; gallium antimonide; Hafnium compounds; hafnium oxide; hydrogen plasma; Plasmas; Rough surfaces; Surface roughness; Surface topography; surface treatment
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2016.2587902

We investigate p-type GaSb MOS capacitors with various HfO 2 thicknesses grown using an atomic layer deposition. GaSb surfaces treated with ex-situ chemical solution and in situ remote hydrogen plasma are inspected. After a series of etching steps, the GaSb surfaces exhibit smooth topography, indicating that this combination of treatments is capable of realizing ultrathin dielectric deposition. After etching processes, the ultrathin (approximately 3 nm) HfO 2 layer deposited successfully on GaSb exhibit high-permittivity (approximately 21) properties as well as equivalent oxide thickness (EOT) of 0.75 nm, which can be attributed to the flat surface. To the best of our knowledge, the EOT of GaSb capacitor prepared using the exploited approach is record low. Furthermore, we find that the interlayer present after hydrogen plasma treatment and forming gas annealing could efficiently passivate interface state density and achieve high C-V modulation. Compared with the benchmark of gate leakage current versus EOT, the electrical performance with low gate leakage current of the GaSb MOS capacitors demonstrates the high feasibility of the proposed treatments.