Silicon oxidation and Si–SiO2 interface of thin oxides

High-resolution transmission electron microscopy (HRTEM) and ellipsometry techniques have been employed to measure thicknesses of silicon oxide, grown at 800°C in dry oxygen, in the thickness range of 2–20 nm. While the oxide growth data measured from TEM obey a nearly linear behavior, those obtained from ellipsometry are seen to vary nonlinearly. The interface structure as function of the increasing oxide thickness was studied using HRTEM. At these oxidation temperatures, the earlier reported variations of roughness at the interface on the oxide thickness for oxides grown at 900°C are not seen. Attempts aimed at correlating the high-resolution transmission electron micrographs with some physical parameters like the refractive index and the dielectric breakdown lead to considerations of the importance of the effect of protrusions of silicon atoms of 1 mm size into SiO2 layers on the interface properties. These findings lead to explanations of some key features concerning the refractive index and density of thin SiO2.

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Thickness-Dependent Interface Parameters of Silicon Oxide Films Grown on Plasma Hydrogenated Silicon

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.159.163 ◽

2010 ◽

Vol 159 ◽

pp. 163-166 ◽

Cited By ~ 1

Author(s):

S. Alexandrova ◽

A. Szekeres

Keyword(s):

Refractive Index ◽

Plasma Treatment ◽

Silicon Oxide ◽

Oxide Films ◽

Oxide Thickness ◽

Hydrogenated Silicon ◽

Oxide Structure ◽

Interface Parameters

In the present paper we discuss the defects at the oxide/Si interface and the structure of silicon oxide films grown on plasma hydrogenated (100) and (111)Si. The effect of oxide thickness ranging from 7 to 40 nm on the interface parameters was examined. Electrically active defects were characterized through C-V and G-V measurements. The dependence of the refractive index on oxide thickness was studied. Information on the oxide structure was inferred through the refractive index evaluated from ellipsometric measurements. From both, the electrical and optical results a characteristic oxide thickness was found, below which the oxide structure is different from SiO2, most probably SiOх. It is related to a modified Si surface during the pre-oxidation plasma treatment and its value depends on Si orientation and pre-clean conditions. A characteristic oxide thickness of 13 nm was found for Si hydrogenated without heating and, of 9 nm for Si hydrogenated at 300oC.

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Effects of N2O Fluence on the PECVD-grown Si-rich SiOx with Buried Si Nanocrystals

MRS Proceedings ◽

10.1557/proc-862-a19.11 ◽

2005 ◽

Vol 862 ◽

Author(s):

Chun-Jung Lin ◽

Hao-Chung Kuo ◽

Chia-Yang Chen ◽

Yu-Lun Chueh ◽

Li-Jen Chou ◽

...

Keyword(s):

Room Temperature ◽

Silicon Oxide ◽

Chemical Vapor ◽

Blue Shift ◽

Annealing Process ◽

Room Temperature Photoluminescence ◽

Transmission Electron ◽

Si Nanocrystals ◽

20 Nm ◽

Oxidation Effect

AbstractThe optimized N2O fluence is demonstrated for plasma enhanced chemical vapor deposition (PECVD) of Si-rich substoichiometric silicon oxide (SiOx) films with buried Si nanocrystals. Strong room-temperature photoluminescence (PL) at 550-870 nm has been observed in SiOx films grown by PECVD under a constant SiH4 fluence of 20 sccm with an N2O fluence varying from 105 sccm to 130 sccm. A 22-nm-redshift in the central PL wavelength has been detected after annealing from 15 min to 180 min. The maximum PL irradiance is observed from the SiOx film grown at the optimal N2O fluence of 120 sccm after annealing for 30 minutes. Larger N2O fluence or longer annealing time leads to a PL band that is blue-shifted by 65 nm and 20 nm, respectively. Such a blue shift is attributed to shrinkage in the size of the Si nanocrystals with the participation of oxygen atoms from N2O incorporated within the SiOx matrix. The (220)-oriented Si nanocrystals exhibit radii ranging from 4.4 nm to 5.0 nm as determined by transmission electron microscopy (TEM). The luminescent lifetime lengthens to 52 μs as the nc-Si size increase to > 4 nm. Optimal annealing times for SiOx films prepared at different N2O fluences are also reported. A longer annealing process results in a stronger oxidation effect in SiOx films prepared at higher N2O fluences, yielding a lower PL irradiance at shorter wavelengths. In contrast, larger Si nanocrystals can be precipitated when the N2O fluence becomes lower; however, such a SiOx film usually exhibits weaker PL at longer wavelength due to a lower nc-Si density. These results indicate that a N2O/SiH4 fluence ratio of 6:1 is the optimized PECVD growth condition for the Si-rich SiO2 wherein dense Si nanocrystals are obtained after annealing.

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Uranium Fixation During Uranium Migration Under an Oxidizing Condition

MRS Proceedings ◽

10.1557/proc-353-1219 ◽

1994 ◽

Vol 353 ◽

Cited By ~ 1

Author(s):

Takashi Murakami ◽

Katsuyuki Tsuzuki ◽

Tsutomu Sato ◽

Hiroshi Isobe ◽

Toshihiko Ohnuki

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Rock Specimen ◽

Uranium Mineral ◽

Ore Deposit ◽

Iron Minerals ◽

Transmission Electron ◽

Uranium Migration ◽

20 Nm

AbstractA rock specimen, collected downstream of the Koongarra uranium ore deposit, Australia, was examined mainly by high resolution transmission electron microscopy in order to understand the uranium fixation mechanism. Uranium was found to exist as saleeite (Mg(UO2)2(PO4)2.10H2O) microcrystals of 1 – 20 nm scattered between iron minerals (mainly goethite and hematite) of 2 – 50 nm. The microtextural relationship between saléeite and the iron minerals revealed that the iron minerals function as catalyst for the formation of saléeite. The intermediate metamict microstructures of the saléeite microcrystals are consistent with the estimated formation age of saléeite, 1 to 3 × 106 years. Uranium has been, thus, fixed as saléeite downstream as well as in the secondary ore deposit. Saléeite in the secondary ore deposit showed completely periodic to fully metamict microstructures, suggesting that saléeite, a major uranium mineral in the secondary ore deposit, probably began to form a few million years ago and continued to form for the next million years.

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Electrical Characteristics of TaOxNy/ZrSixOy Stack Gate Dielectric for MOS Device Applications

MRS Proceedings ◽

10.1557/proc-670-k4.6 ◽

2001 ◽

Vol 670 ◽

Author(s):

Hyungsuk Jung ◽

Hyundoek Yang ◽

Kiju Im ◽

Hyunsang Hwang

Keyword(s):

Interfacial Layer ◽

Silicon Oxide ◽

Gate Dielectric ◽

Oxide Thickness ◽

Tem Analysis ◽

Mos Capacitors ◽

Zirconium Silicate ◽

Transmission Electron ◽

High K ◽

Device Applications

ABSTRACTThis letter describes a unique process for the preparation of high quality tantalum oxynitride (TaOxNy) with zirconium silicate (ZrSixOy) as an interfacial layer for use in gate dielectric applications. Compared with conventional native silicon oxide and oxynitride as an interfacial layer, tantalum oxynitride (TaOxNy) MOS capacitors using zirconium silicate (ZrSixOy) as an interfacial layer exhibit lower leakage current levels at the same equivalent oxide thickness. We were able to confirm TaOxNy/ZrSixOy stack structure by auger electron spectroscopy (AES) and transmission electron microscope (TEM) analysis. The estimated dielectric constant of TaOxNy and ZrSixOywere approximately 67 and 7, respectively. The zirconium silicate is a promising interfacial layer for future high-k gate dielectric applications.

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Microstructural Characterization Methods for Magnetic Thin Films

MRS Proceedings ◽

10.1557/proc-562-3 ◽

1999 ◽

Vol 562 ◽

Cited By ~ 2

Author(s):

J. E. Wittig ◽

J. Bentley ◽

T. P. Nolan

Keyword(s):

Thin Films ◽

High Resolution ◽

Microstructural Characterization ◽

Magnetic Thin Films ◽

Complete Analysis ◽

Structure Property ◽

Characterization Methods ◽

Transmission Electron ◽

High Resolution Tem ◽

20 Nm

ABSTRACTMicrostructural characterization is key to determining the structure-property-processing relationships required to optimize the performance of magnetic thin films for longitudinal magnetic recording. Since the grain size of modem recording media is on the order of 10 to 20 nm, only high-resolution characterization methods such as transmission electron microscopy (TEM) can accurately describe the microstructure. Complete analysis requires a combination of conventional and high-resolution TEM imaging with analytical methods such as energy dispersivespectroscopy and energy-filtered TEM imaging. This paper provides examples from CoCr(Pt,Ta) alloys that reveal the strengths and limitations of these characterization methods as they apply to microstructural characterization of magnetic thin films.

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Studies of Defect Structure in Epitaxial AlN/GaN Films Grown on (111) 3C-SiC

Nanomaterials ◽

10.3390/nano11051299 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1299

Author(s):

Andreea Bianca Serban ◽

Vladimir Lucian Ene ◽

Doru Dinescu ◽

Iulia Zai ◽

Nikolay Djourelov ◽

...

Keyword(s):

High Resolution ◽

Diffusion Length ◽

X Ray Diffraction ◽

Correlation Lengths ◽

Transmission Electron ◽

Dislocation Densities ◽

Elemental Diffusion ◽

20 Nm ◽

The Relationship

Several aspects such as the growth relation between the layers of the GaN/AlN/SiC heterostructure, the consistency of the interfaces, and elemental diffusion are achieved by High Resolution Transmission Electron Microscopy (HR-TEM). In addition, the dislocation densities together with the defect correlation lengths are investigated via High-Resolution X-ray Diffraction (HR-XRD) and the characteristic positron diffusion length is achieved by Doppler Broadening Spectroscopy (DBS). Moreover, a comparative analysis with our previous work (i.e., GaN/AlN/Si and GaN/AlN/Al2O3) has been carried out. Within the epitaxial GaN layer defined by the relationship (111) 3C-SiC || (0002) AlN || (0002) GaN, the total dislocation density has been assessed as being 1.47 × 1010 cm−2. Compared with previously investigated heterostructures (on Si and Al2O3 substrates), the obtained dislocation correlation lengths (Le = 171 nm and Ls =288 nm) and the mean distance between two dislocations (rd = 82 nm) are higher. This reveals an improved crystal quality of the GaN with SiC as a growth template. In addition, the DBS measurements upheld the aforementioned results with a higher effective positron diffusion length = 75 ± 20 nm for the GaN layer.

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HRTEM Image Simulations for Gate Oxide Metrology

Microscopy and Microanalysis ◽

10.1017/s1431927600037892 ◽

2000 ◽

Vol 6 (S2) ◽

pp. 1080-1081

Author(s):

S. Taylor ◽

J. Mardinly ◽

M.A. O'Keefe ◽

R. Gronsky

Keyword(s):

Silicon Oxide ◽

Spherical Aberration ◽

Semiconductor Industry ◽

Gate Oxide ◽

Oxide Thickness ◽

Objective Lens ◽

Specimen Thickness ◽

Hrtem Image ◽

Transmission Electron ◽

Image Simulations

High resolution transmission electron microscopy (HRTEM) has found extensive use in the semiconductor industry for performing device metrology and characterization. However, shrinking device dimensions (gate oxides are rapidly approaching 10Å) present challenges to the use of HRTEM for many applications, including gate oxide metrology. In this study, we performed HRTEM image simulations of a MOSFET device to examine the accuracy of HRTEM in measuring gate oxide thickness. Length measurements extracted from simulated images were compared to actual dimensions in the model structure to assess TEM accuracy. The effects of specimen tilt, specimen thickness, objective lens defocus and coefficient of spherical aberration (CS) on measurement accuracy were explored for nominal 10Å and 16Å gate oxide thicknesses.The gate oxide was modeled as an amorphous silicon oxide situated between a gate electrode and substrate, both modeled as single crystal Si(100). Image simulations of the sandwich structure were performed in cross-section (with Si[110] parallel to beam direction) using the multislice approximation for a 200 kV microscope with Cs=0.5mm.

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Low Temperature Synthesis of Silicon Oxide Nanowires

MRS Proceedings ◽

10.1557/proc-879-z10.10 ◽

2005 ◽

Vol 879 ◽

Author(s):

Rezina Siddique ◽

George Sirinakis ◽

Michael A. Carpenter

Keyword(s):

Electron Microscopy ◽

Silicon Nanowires ◽

Physical Vapor Deposition ◽

Gas Flow ◽

Silicon Oxide ◽

Logic Gates ◽

Transmission Electron ◽

Potential Applications ◽

Lower Temperature ◽

20 Nm

AbstractSilicon Nanowires (SiNWs) have many potential applications that include diodes, transistors, logic gates, circuitry, and sensors. SiNWs also open the possibility for integrating optoelectronics with microelectronics, since silicon has semiconducting properties and amorphous silicon nanowires have been shown to emit blue light. It has been demonstrated that SiNWs have tunable electrical properties, depending on the dopant used. With such a range of applications, the ability to mass-produce silicon nanowires simply and easily with no other source of silicon needed other than the substrate itself will prove very useful. Such methods have previously been reported, but our method involves production of the SiNWs at a lower temperature than those widely observed. A (100) silicon substrate was cleaned for five minutes each in ethanol followed by acetone. Films with thicknesses of less than 20 nm of either gold or 60/40 gold/palladium were deposited on the substrate through physical vapor deposition to serve as the growth center for the SiNWs. The samples were placed in a furnace and annealed to 900° C, under a 1500 sccm flow of argon at atmospheric pressure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization of the SiNWs. The resulting SiNWs were amorphous in structure and very convoluted, with lengths on the order of tens of microns, diameters of 40 nm and a bed thickness of approximately 10 m. The effect of varying gold concentration, annealing time, temperature, and gas flow rate were then investigated. The results, which will be discussed in further detail, indicate that adjusting these parameters allows for control over the length, thickness, density, and morphology of the nanowires.

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