Radiation effects in Al2O3-based MOS capacitors

We studied the γ-ray (60Co) radiation response of MOS capacitors with an atomic layer deposited Al2O3 as insulating layer up to a total dose of 6.2 kGy. Preirradiation electrical characterization showed a voltage instability for samples with an n-type substrate due to tunneling transitions between the substrate and preexisting defects inside the dielectric layer. No instability was observed in the case of p-type samples, aming them suitable for the study of the radiation effects in these devices. With respect to the radiation response, real-time capacitance-voltage (C-V) measurements showed a monotonic shift of the C-V characteristic towards negative voltages, indicating and increase of the positive trapped charge with dose, which accords with previous results in the literature. From this results the fraction of generated holes that is captured in a trap could be calculated, resulting in a value of 30%, what suggests a high trapping efficiency. Moreover, from the stretch-out of the C-V curve, an increase in the Si/Al2O3 interface trap density was observed up to 4 kGy when saturation occurred.

[1]  L. Larcher,et al.  Modeling TANOS Memory Program Transients to Investigate Charge-Trapping Dynamics , 2009, IEEE Electron Device Letters.

[2]  B. Govoreanu,et al.  A Novel Trapping/Detrapping Model for Defect Profiling in High- $k$ Materials Using the Two-Pulse Capacitance–Voltage Technique , 2010, IEEE Transactions on Electron Devices.

[3]  Kinam Kim,et al.  A novel SONOS structure of SiO/sub 2//SiN/Al/sub 2/O/sub 3/ with TaN metal gate for multi-giga bit flash memories , 2003, IEEE International Electron Devices Meeting 2003.

[4]  Won-Ju Cho,et al.  High performance silicon-on-insulator based ion-sensitive field-effect transistor using high-k stacked oxide sensing membrane , 2011 .

[5]  Daniel M. Fleetwood,et al.  Low-frequency noise and radiation response of metal-oxide-semiconductor transistors with Al2O3/SiOxNy/Si(100) gate stacks , 2003 .

[6]  W. Marsden.  I and J , 2012 .

[7]  L. Larcher,et al.  Investigation of trapping/detrapping mechanisms in Al2O3 electron/hole traps and their influence on TANOS memory operations , 2010, Proceedings of 2010 International Symposium on VLSI Technology, System and Application.

[8]  Ronald Kakoschke,et al.  Use of Al2O3 as inter-poly dielectric in a production proven 130 nm embedded Flash technology , 2008 .

[9]  R. J. Luyken,et al.  Retention time of novel charge trapping memories using Al/sub 2/O/sub 3/ dielectrics , 2003, ESSDERC '03. 33rd Conference on European Solid-State Device Research, 2003..

[10]  J.A. Felix,et al.  Bias-temperature instabilities and radiation effects in MOS devices , 2005, IEEE Transactions on Nuclear Science.

[11]  Jian Fu Zhang,et al.  Energy and Spatial Distributions of Electron Traps Throughout $\hbox{SiO}_{2}/\hbox{Al}_{2}\hbox{O}_{3}$ Stacks as the IPD in Flash Memory Application , 2010, IEEE Transactions on Electron Devices.

[12]  E. Yilmaz,et al.  Use of Al2O3 layer as a dielectric in MOS based radiation sensors fabricated on a Si substrate , 2008 .

[14]  L. Larcher,et al.  A Comprehensive Understanding of the Erase of TANOS Memories Through Charge Separation Experiments and Simulations , 2011, IEEE Transactions on Electron Devices.

[15]  Ronald D. Schrimpf,et al.  Radiation-Induced Charge Trapping in Thin , 2003 .

[16]  Fernanda Irrera,et al.  Characterization of charge trapping in SiO2/Al2O3 dielectric stacks by pulsed C-V technique , 2007, Microelectron. Reliab..

[17]  L. S. Salomone,et al.  Charge trapping/detrapping in HfO2-based MOS devices , 2011, 2011 Argentine School of Micro-Nanoelectronics, Technology and Applications.

[18]  J. M. Rafí,et al.  Electrical characteristics of metal-insulator-semiconductor structures with atomic layer deposited Al2O3, HfO2, and nanolaminates on different silicon substrates , 2011 .

[19]  J. F. Zhang,et al.  Two-Pulse C – V : A New Method for Characterizing Electron Traps in the Bulk of SiO 2 / high-κ Dielectric Stacks , 2009 .

[20]  A. Paccagnella,et al.  Heavy-Ion Induced Threshold Voltage Shifts in Sub 70-nm Charge-Trap Memory Cells , 2011, IEEE Transactions on Nuclear Science.

[21]  T. Schram,et al.  Influence of Al2O3 crystallization on band offsets at interfaces with Si and TiNx , 2011 .

[22]  R. Degraeve,et al.  Trap Spectroscopy by Charge Injection and Sensing (TSCIS): A quantitative electrical technique for studying defects in dielectric stacks , 2008, 2008 IEEE International Electron Devices Meeting.

[23]  A. Al-Kabbani,et al.  Characteristics and radiation effects of MOS capacitors with Al2O3 layers in p-type silicon , 1995 .