The Dependence of ETCH Pit Density on the Interfacial Oxygen Levels in Thin Silicon Layers Grown by Ultra High Vacuum Chemical Vapor Deposition

ABSTRACTFor low temperature silicon epitaxy it is not only important to have an oxygen free environment during growth but also an initial silicon surface free of trace concentrations of oxygen, carbon and other impurities. Variations in the pre-clean process (using the standard ex-situ aqueous hydrofluoric acid dip) used for ultra high vacuum chemical vapor depostion (UHVCVD) of silicon, result in interfacial oxygen levels ranging from 2 × 1012atoms/cm2 to 1014atoms/cm2 as measured by secondary ion ion mass spectroscopy (SIMS). Using a dilute Schimmel etch we have delineated the dislocations in the thin silicon epitaxial layers grown by UHVCVD. Correlation of the etch pit density to the interfacial oxygen levels suggests a power law dependence. Plausibility arguments are presented to explain this power law dependence.

Download Full-text

One-Step Cost-Effective Growth of High-Quality Epitaxial Ge Films on Si (100) Using a Simplified PECVD Reactor

Electronic Materials ◽

10.3390/electronicmat2040033 ◽

2021 ◽

Vol 2 (4) ◽

pp. 482-494

Author(s):

Jignesh Vanjaria ◽

Venkat Hariharan ◽

Arul Chakkaravarthi Arjunan ◽

Yanze Wu ◽

Gary S. Tompa ◽

...

Keyword(s):

Film Growth ◽

High Vacuum ◽

Chemical Vapor ◽

Cost Effective ◽

Single Step ◽

Film Deposition ◽

Ultra High Vacuum ◽

Ex Situ ◽

High Quality ◽

X Ray

Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH4) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (>10−6 Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy.

Download Full-text

Self-assembled Ge quantum dots on SiC substrates grown by UHV-CVD

MRS Proceedings ◽

10.1557/proc-742-k2.20 ◽

2002 ◽

Vol 742 ◽

Author(s):

C. Calmes ◽

V. Le ◽

D. Bouchier ◽

S. E. Saddow ◽

V. Yam ◽

...

Keyword(s):

Quantum Dots ◽

High Vacuum ◽

Chemical Vapor ◽

High Energy ◽

Surface Cleaning ◽

Ultra High Vacuum ◽

Ex Situ ◽

First Results ◽

Ge Quantum Dots

AbstractWe report our first results using a ultra high vacuum chemical vapor deposition (UHV-CVD) system to form Ge quantum dots on off-axis SiC substrates. Pure SiH4 and hydrogen-diluted GeH4 were used as gas precursors. The SiC substrates were chemically cleaned using the modified RCA process and the SiO2 layer was removed in-situ under a low SiH4 flow rate at a temperature between 1030°C and 1080°C. The Ge quantum dots were grown at a temperature of 750°C. In-situ reflection high-energy electron diffraction (RHEED) was used to monitor the surface cleaning and the Ge quantum dot growth. Ex-situ scanning electron microscope and atomic force microscopy were used to confirm the presence of Ge dots. The observed dots are smaller (350 Å width and 100 Å height) than similar Ge dots grown on Si.

Download Full-text

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010648x ◽

1988 ◽

Vol 46 ◽

pp. 884-885

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove ◽

R. T. Tung

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Defect Density ◽

High Vacuum ◽

Ultra High Vacuum ◽

Ex Situ ◽

Metal Base ◽

In Situ Experiments ◽

Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Download Full-text

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154287 ◽

1989 ◽

Vol 47 ◽

pp. 462-463

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Electron Diffraction ◽

High Vacuum ◽

High Energy ◽

Energy Electron ◽

Ultra High Vacuum ◽

Ex Situ ◽

Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Download Full-text

Challenge to 200 mm 3C-SiC Wafers Using SOI

Materials Science Forum ◽

10.4028/www.scientific.net/msf.483-485.205 ◽

2005 ◽

Vol 483-485 ◽

pp. 205-208 ◽

Cited By ~ 10

Author(s):

Motoi Nakao ◽

Hirofumi Iikawa ◽

Katsutoshi Izumi ◽

Takashi Yokoyama ◽

Sumio Kobayashi

Keyword(s):

Cross Section ◽

Vapor Deposition ◽

Seed Layer ◽

High Vacuum ◽

Chemical Vapor ◽

Ultra High Vacuum ◽

Average Thickness ◽

Entire Region ◽

Transmission Electron ◽

Good Crystallinity

200 mm wafer with 3C-SiC/SiO2/Si structure has been fabricated using 200 mm siliconon- insulator (SOI) wafer. A top Si layer of 200 mm SOI wafer was thinned down to approximately 5 nm by sacrificial oxidization, and the ultrathin top Si layer was metamorphosed into a 3C-SiC seed layer using a carbonization process. Afterward, an epitaxial SiC layer was grown on the SiC seed layer with ultra-high vacuum chemical vapor deposition. A cross-section transmission electron microscope indicated that a 3C-SiC seed layer was formed directly on the buried oxide layer of 200 mm wafer. The epitaxial SiC layer with an average thickness of approximately 100 nm on the seed was recognized over the entire region of the wafer, although thickness uniformity of the epitaxial SiC layer was not as good as that of SiC seed layer. A transmission electron diffraction image of the epitaxial SiC layer showed a monocrystalline 3C-SiC(100) layer with good crystallinity. These results indicate that our method enables to realize 200 mm SiC wafers.

Download Full-text

Ultra-high vacuum chemical vapor deposition and in situ characterization of titanium oxide thin films

Journal of Materials Research ◽

10.1557/jmr.1991.1913 ◽

1991 ◽

Vol 6 (9) ◽

pp. 1913-1918 ◽

Cited By ~ 31

Author(s):

Jiong-Ping Lu ◽

Rishi Raj

Keyword(s):

Thin Films ◽

Chemical Vapor Deposition ◽

Titanium Oxide ◽

Vapor Deposition ◽

Photoelectron Spectroscopy ◽

High Vacuum ◽

Chemical Vapor ◽

Titanium Isopropoxide ◽

Ultra High Vacuum

Chemical vapor deposition (CVD) of titanium oxide films has been performed for the first time under ultra-high vacuum (UHV) conditions. The films were deposited through the pyrolysis reaction of titanium isopropoxide, Ti(OPri)4, and in situ characterized by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). A small amount of C incorporation was observed during the initial stages of deposition, through the interaction of precursor molecules with the bare Si substrate. Subsequent deposition produces pure and stoichiometric TiO2 films. Si–O bond formation was detected in the film-substrate interface. Deposition rate was found to increase with the substrate temperature. Ultra-high vacuum chemical vapor deposition (UHV-CVD) is especially useful to study the initial stages of the CVD processes, to prepare ultra-thin films, and to investigate the composition of deposited films without the interference from ambient impurities.

Download Full-text