IEEE TRANSACTIONS ON ELECTRONDEVICES, VOL. 60, NO. 5, MAY 2013 1555 Electrical Characteristics of Al 2 O 3 /InSb MOSCAPs and the Effect of Postdeposition Annealing Temperatures Hai Dang Trinh, Yueh Chin Lin, Edward Yi Chang, Senior Member, IEEE, Ching-Ting Lee, Fellow, IEEE , Shin-Yuan Wang, Hong Quan Nguyen, Yu Sheng Chiu, Quang Ho Luc, Hui-Chen Chang, Chun-Hsiung Lin, Simon Jang, and Carlos H. Diaz, Fellow, IEEE Abstract— The characteristics of Al 2 O 3 /InSb MOSCAPs processed with different postdeposition annealing (PDA) temperatures are investigated. X-ray photoelectron spectroscopy analysis shows a significant reduction of InSb-oxides after HCl plus trimethyl aluminum treatment and oxide deposition. Multifrequency capacitance-voltage (C–V ) characteristics exhibit low-frequency and asymmetrical C–V behaviors, in which capac- itance in the InSb conduction band side is lower than in the valence band side. The electrical properties of the MOSCAPs are sensitive to PDA temperature and degraded significantly at PDA temperature > 300 °C. This degradation is closely related to the diffusion of In, Sb into Al 2 O 3 as indicated by transmission electron microscopy analyses. Index Terms— Al 2 O 3 , asymmetrical C –V , atomic layer depo- sition (ALD), InSb, MOS, post deposition annealing (PDA). I. I NTRODUCTION B ESIDES the use in infrared imaging systems, high carrier mobility, narrow-gap InSb has drawn attention for its potential in extremely high-speed, low-power CMOS devices application such as nanowire, quantum well (QW) or band-to-band tunneling (T) field-effect-transistors (FETs). Among III–V compounds, InSb has the highest electron Manuscript received December 17, 2012; revised February 2, 2013; accepted March 15, 2013. Date of current version April 18, 2013. This work was supported by the Taiwan National Science Council under Contract 101-2923- E-009-002-MY3 and Contract 99-2221-E-164-MY3. H. D. Trinh was with the Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan. He is currently with the Manufacturing Company Limited, Hsinchu Science Park, Hsinchu 300, Taiwan (e-mail: trinhhaidang@gmail.com). Y. C. Lin, H. Q. Nguyen, Y. S. Chiu, and Q. H. Luc are with the Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (e-mail: nctulin@yahoo.com.tw; quansply@yahoo.com; laurance0319@yahoo.com.tw; lucquangho@gmail.com). E. Y. Chang is with the Department of Materials Science and Engineering and the Department of Electronic Engineering, National Chiao Tung Univer- sity, Hsinchu 300, Taiwan (e-mail: edc@mail.nctu.edu.tw). C.-T. Lee is with Department of Electrical Engineering, National Cheng Kung University, 01 University Road, Tainan 701, Taiwan (e-mail: ctlee@ee.ncku.edu.tw). S.-Y. Wang is with the Department of Electronic Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (e-mail: leoplct@gmail.com). H.-C. Chang, C.-H. Lin, S. M. Jang, and C. H. Diaz are with the Taiwan Semiconductor Manufacturing Company Limited, Hsinchu Science Park, Hsinchu 300, Taiwan (e-mail: changhcm@tsmc.com; linchzzz@tsmc.com; smjang@tsmc.com; chdiaz@tsmc.com). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TED.2013.2254119 mobility of 7.7 × 10 4 cm 2 V -1 s -1 and hole mobility of 840 cm 2 V -1 s -1 [1], which promise of both n- and p- channel high-performance transistors. InSb-based QWFETs demonstrated very-high speed performance at low supply voltage (0.5 V) for both n- and p-channels devices [2], [3]. The integration of InSb on Si for MOS devices application was also reported [4]. For both infrared and CMOS applications, the deposition of dielectric layer with good quality interfacial properties is essential for the effective performance of devices. Several methods such as anodic oxidation, plasma-enhanced chemical vapor deposition (PECVD), remote PECVD, and low-temperature chemical vapor deposition are used to deposit the insulator/oxide layer on InSb for studying. However, the study of InSb MOS capacitors (MOSCAPs) using atomic layer deposition (ALD) oxide is still seldom [4]–[7]. The ALD method is well known to be a robust and manu- facturable process, which is promising for manufacturing of CMOS technology. Because InSb has low thermal budget [1], the electrical characteristics of the ALD oxide/InSb MOSCAPs are sensitive to thermal processes. In this paper, the electrical properties of ALD Al 2 O 3 /InSb MOSCAPs and their dependent on postdeposition annealing (PDA) temperatures are studied. The multifrequency asymmetrical C –V behavior of Al 2 O 3 /n-InSb MOSCAPs due to the low density of state (DOS) in InSb conduction band is experimentally observed in this paper. The out diffusion of In, Sb atoms into Al 2 O 3 is found to be the major effect on the electrical degradation of the MOSCAPs such as hysteresis, frequency dispersion, C –V modulation, C –V stretch-out, and interface density of states D it . II. MATERIALS AND EXPERIMENT Wafers used in this research are InSb (100) undoped sub- strate, naturally n-type behavior with donor concentration of 2.2 × 10 16 cm -3 at room temperature, determined by Hall measurement. The wafers are initially degreased by rinsing in acetone and isopropanol for 2 min each. The samples are dipped in the diluted HCl 4% solution for 2 min, rising in deionized water, and blown dry by N 2 gas. The samples are then loaded into ALD chamber (Cambridge NanoTech Fiji 202 DSC) within 5 min after cleaning. In ALD chamber, the samples are precleaned by using ten pulses of trimethyl alu- minum (TMA)/Ar [8]–[10] before the deposition of 85 cycles 0018-9383/$31.00 © 2013 IEEE