Radiation-induced interface state generation in MOS devices with reoxidised nitrided SiO2 gate dielectrics

AbstractThis paper reports on the formation of high quality ultrathin oxynitride gate dielectric by in-situ rapid thermal multiprocessing. Four such gate dielectrics are discussed here; (i) in-situ NO-annealed SiO2, (ii) N2O- or NO- or O2-grown bottom oxide/RTCVD SiO2/thermal oxide, (iii) N2O-grown bottom oxide/Si3N4/N2O-oxide (ONO) and (iv) N2O-grown bottom oxide/RTCVD SiO2/N2O-oxide. Results show that capacitors with NO-based oxynitride gate dielectrics, stacked oxynitride gate dielectrics with varying quality of bottom oxide (O2/N2O/NO), and the ONO structures show high endurance to interface degradation, low defect-density and high charge-to-breakdown compared to thermal oxide. The N2O-last reoxidation step used in the stacked dielectrics and ONO structures is seen to suppress charge trapping and interface state generation under Fowler-Nordheim injection. The stacked oxynitride gate dielectrics also show excellent MOSFET performance in terms of transconductance and mobility. While the current drivability and mobilities are found to be comparable to thermal oxide for N-channel MOSFET's, the hot-carrier immunity of N-channel MOSFET's with the N2O-oxide/CVD-SiO2/N2O-oxide gate dielectrics is found to be significantly enhanced over that of conventional thermal oxide.

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Effect of Growth Conditions on the Reliability of Ultrathin MOS Gate Oxides

MRS Proceedings ◽

10.1557/proc-428-355 ◽

1996 ◽

Vol 428 ◽

Cited By ~ 2

Author(s):

Tien-Chun Yang ◽

Krishna C. Saraswat

Keyword(s):

Gate Oxide ◽

Interface State ◽

Growth Conditions ◽

Physical Stress ◽

Constant Current ◽

Strong Function ◽

Oxidation Rates ◽

Mos Devices ◽

State Generation ◽

Mos Gate

AbstractIn this work we demonstrate that in MOS devices the reliability of ultrathin (< 100Å) gate oxide is a strong function of growth conditions, such as, temperature and the growth rate. In addition, for constant current gate injection the degradation of SiO2 is enhanced as the thickness is reduced. We attribute this to physical stress in SiO2 resulting from the growth process. The degradation is always more for those growth conditions which result in higher physical stress in SiO2. Higher temperatures and slower oxidation rates allow stress relaxation through viscous flow and hence result in SiO2 of better reliability. We also found that for constant current stressing, the interface damage is more at the collecting electrode than at the injecting electrode. ΔDit (stress induced interface state generation) can be reduced after a high temperature Ar post anneal after the gate oxide growth.

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Transconductance degradation and interface state generation in metal‐oxide‐semiconductor field‐effect transistors with oxynitride gate dielectrics under hot‐carrier stress

Applied Physics Letters ◽

10.1063/1.102819 ◽

1990 ◽

Vol 56 (3) ◽

pp. 250-252 ◽

Cited By ~ 8

Author(s):

G. Q. Lo ◽

W. C. Ting ◽

D. K. Shih ◽

D. L. Kwong

Keyword(s):

Metal Oxide ◽

Field Effect ◽

Gate Dielectrics ◽

Field Effect Transistors ◽

Interface State ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Hot Carrier ◽

Hot Carrier Stress ◽

State Generation

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Fabrication of High Quality MOS Devices for Application in Hazardous Environments Based on RTP Gate Dielectrics with In Situ RTCVD of Polysilicon Gates

MRS Proceedings ◽

10.1557/proc-300-587 ◽

1993 ◽

Vol 300 ◽

Author(s):

B. Fröschle ◽

H.P. Bruemmer ◽

W. Lang ◽

K. Neumeier ◽

P. Ramm

Keyword(s):

Threshold Voltage ◽

Gate Dielectrics ◽

Chemical Vapor ◽

Process Variations ◽

Interface State ◽

State Density ◽

Breakdown Field ◽

Polysilicon Gate ◽

Radiation Induced

ABSTRACTProcess modules for MOS gate fabrication were developed which can be completed subsequently in one RTP reactor: atmospheric process sequences for gate oxides and oxynitrides as well as low pressure chemical vapor deposition of polysilicon (RTCVD). Prior to the Rapid Thermal Oxidation (RTO), the wafers were treated with a Rapid Thermal Cleaning process (RTC) in H2/Ar ambient. After the desoxidation step the RTO was done in O2/H2/Ar followed by an anneal (RTA) for the gate oxide or a nitridation in NH3 (RTN) and reoxidation for the oxynitrides, respectively. The polysilicon gate electrode was fabricated either by RTCVD in situ or in a conventional furnace reactor. The two-step RTCVD process resulted in a very good thickness uniformity for the polysilicon layers of 3% (3mm from the edge). The influence of the process variations on breakdown field, fixed oxide charge, interface state density, flatband voltage, and threshold voltage of the different types of gate dielectrics was investigated. The charges and voltages were determined by LF-HF CV measurements. In order to characterize the radiation tolerance of electronic devices, radiation induced flatband and threshold voltage shifts as well as the build up of interface charges were determined. The irradiation was performed at a Co - 60 gamma source. Breakdown fields in the range of 19 MV/cm, interface state densities of less than 109 eV−1cm−2, and radiation induced threshold voltage shifts below 0.1 V after 1.5 Mrad(Si) were obtained.

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Structure and Growth of N2O Gate Oxynitrides

MRS Proceedings ◽

10.1557/proc-428-393 ◽

1996 ◽

Vol 428 ◽

Cited By ~ 1

Author(s):

K. A. Ellis ◽

E. C. Carr ◽

R. A. Buhrman

Keyword(s):

Flow Rate ◽

Atomic Oxygen ◽

Gate Dielectrics ◽

Total Concentration ◽

Nitrogen Sources ◽

Interface State ◽

Silicon Oxynitride ◽

Nitrogen Incorporation ◽

Exothermic Decomposition ◽

State Generation

AbstractA series of investigations have been conducted into the properties of N2O silicon oxynitride gate dielectrics, and the various methods of their growth. One of the principle advantages of these oxides is their resistance to interface state generation. This is linked to the presense of nitrogen near the substrate interface, where it is triply bonded to silicon. It is also demonstrated that during N2O-based furnace growth, the total concentration of NOx species varies strongly with the flow rate of N2O. This has been correlated to the temperature profile of the furnace, which can be affected by the exothermic decomposition of N2O. This property has been exploited to controllably adjust the rate of nitrogen incorporation by up to a factor of three. Although nitrogen incorporation during furnace processing is generally stable, it is shown that atomic oxygen is capable of removing previously incorporated nitrogen. Sources of atomic oxygen include the decomposition of N2O during RTP treatment, N2O processing in a high flow rate furnace, or from ozone annealing.

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Gate Oxynitride Grown in N2O and Annealed in NO Using Rapid Thermal Processing

MRS Proceedings ◽

10.1557/proc-387-241 ◽

1995 ◽

Vol 387 ◽

Cited By ~ 1

Author(s):

S. C. Sun ◽

C. H. Chen ◽

J. C. Lou ◽

L. W. Yen ◽

C. J. Lin

Keyword(s):

Gate Dielectrics ◽

Charge Trapping ◽

Oxide Thickness ◽

Interface State ◽

No Oxidation ◽

Nitrogen Accumulation ◽

Electrical Stress ◽

Wide Range ◽

State Generation ◽

Stress Induced Leakage Current

AbstractIn this paper a new technique for the formation of high quality ultrathin gate dielectrics is proposed. Gate oxynitride was first grown in N2O and then annealed by in-situ rapid thermal NO-nitridation. This approach has the advantage of providing a tighter nitrogen distribution and a higher nitrogen accumulation at or near the Si-SiO2 interface than either N2O oxynitride or nitridation of SiO2 in the NO ambient. It is applicable to a wide range of oxide thickness because the initial rapid thermal N2O oxidation rate is slow but not as self-limited as NO oxidation. The resulting gate dielectrics have reduced charge trapping, lower stress-induced leakage current and significant resistance to interface state generation under electrical stress

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Radiation‐induced interface‐state generation in reoxidized nitrided SiO2

Journal of Applied Physics ◽

10.1063/1.350390 ◽

1992 ◽

Vol 71 (2) ◽

pp. 1029-1031 ◽

Cited By ~ 7

Author(s):

V. Ramgopal Rao ◽

J. Vasi

Keyword(s):

Interface State ◽

State Generation ◽

Radiation Induced

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Ensemble Monte Carlo study of interface-state generation in low-voltage scaled silicon MOS devices

IEEE Transactions on Electron Devices ◽

10.1109/16.502424 ◽

1996 ◽

Vol 43 (7) ◽

pp. 1123-1132 ◽

Cited By ~ 18

Author(s):

J.J. Ellis-Monaghan ◽

R.B. Hulfachor ◽

K.W. Kim ◽

M.A. Littlejohn

Keyword(s):

Monte Carlo ◽

Low Voltage ◽

Monte Carlo Study ◽

Interface State ◽

Ensemble Monte Carlo ◽

Mos Devices ◽

State Generation

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Low Temperature (850 °C) Two-Step N2O Annealed Thin Gate Oxides

MRS Proceedings ◽

10.1557/proc-428-405 ◽

1996 ◽

Vol 428 ◽

Author(s):

Chao Sung Lai ◽

Chung Len Lee ◽

Tan Fu Lei ◽

Tien Sheng Chao ◽

Chun Hung Peng ◽

...

Keyword(s):

Low Temperature ◽

Gate Dielectric ◽

Gate Dielectrics ◽

Charge Trapping ◽

Interface State ◽

Constant Current ◽

Short Channel ◽

Gate Oxides ◽

Current Stressing ◽

State Generation

AbstractThe electrical characteristics of thin gate dielectrics prepared by low temperature (850 °C) two-step N20 nitridation (LTN) process are presented. The gate oxides were grown by wet oxidation at 800 °C and then annealed in N2O at 850 °C. The oxide with N2O anneal, even for low temperature (850 °C), had nitrogen incorporation at oxide/silicon interface. The charge trapping phenomena and interface-state generation (ΔDitm) induced by constant current stressing were reduced and charge-to-breakdown (Qbd) under constant current stressing was increased. This LTN oxynitride was used as gate dielectric for N-channel MOSFET, whose hot-canrier immunity was shown improved and reverse short channel effect (RSCE) was suppressed.

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