Time-Resolved Reflectivity Measurements of Silicon And Germanium Using A Pulsed Excimer Laser

1985 ◽  
Vol 51 ◽  
Author(s):  
G. E. Jellison ◽  
D. H. Lowndes ◽  
D. N. Mashburn ◽  
R. F. Wood
Keyword(s):  
Excimer Laser ◽  
Surface Region ◽  
Finite Energy ◽  
Time Resolved ◽  
Model Calculations ◽  
Near Surface ◽  
Maximum Reflectivity ◽  
Liquid Phases ◽  
Silicon And Germanium ◽  
Melt Duration

ABSTRACTTime-resolved reflectivity measurements of silicon and germanium have been made during pulsed KrF excimer laser irradiation. The reflectivity was measured simultaneously at both 1152 and 632.8 nm wavelengths, and the energy density of each laser pulse was monitored. The melt duration and the time of the onset of melting were measured and compared with the results of melting model calculations. For energy densities just above the melting threshold, it was found that the melt duration was never less than 20 ns for Si and 25 ns for Ge, while the maximum reflectivity increased from the value of the hot solid to that of the liquid over a finite energy range. These results, along with a reinterpretation of earlier time-resolved ellipsometry measurements, indicate that, during the melt-in process, the near-surface region does not melt homogeneously, but rather consists of a mixture of solid and liquid phases. The reflectivity at the onset of melting and in the liquid phase have been measured at both 632.8 and 1152 nm, and are compared with the results found in the literature.

Time-Resolved Studies of Rapid Solidification in Highly Undercooled Molten Silicon

1984 ◽  
Vol 35 ◽  
Author(s):  
D.H. Lowndes ◽  
G.E. Jellison ◽  
R.F. Wood ◽  
S.J. Pennycook ◽  
R.W. Carpenter
Keyword(s):  
Liquid Layer ◽  
Laser Energy ◽  
Surface Region ◽  
Experimental Information ◽  
Molten Silicon ◽  
Undercooled Liquid ◽  
Time Resolved ◽  
Model Calculations ◽  
Near Surface ◽  
Si Substrates

ABSTRACTA KrF (248 nm) pulsed laser was used to melt 90-, 190-, and 440-nm thick amorphous silicon layers produced by Si ion implantation into (100) crystalline Si substrates. Time-resolved reflectivity measurements at two different probe wavelengths (633 nm and 1.15 μm) and post-irradiation TEM measurements were used to study the formation of an undercooled liquid Si phase and the subsequent solidification processes. The time-resolved measurements provide new experimental information about the nucleation of fine-grained Si crystallites in undercooled liquid Si, at low laser energy densities (Eℓ), and about the growth of large-grained Si in the near-surface region at higher Eℓ. Measurements with the infrared probe beam reveal the presence of a buried, propagating liquid layer at low ??. Model calculations indicate that this liquid layer is generated in part by the release of latent heat associated with the nucleation and growth process.

Low Temperature Crystallization of Amorphous Silicon Films Using an Excimer Laser

1989 ◽  
Vol 149 ◽  
Author(s):  
S. E. Ready ◽  
J. B. Boyce ◽  
R. Z. Bachrach ◽  
R. I. Johnson ◽  
K. Winer ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Excimer Laser ◽  
Laser Energy ◽  
Amorphous Material ◽  
Surface Region ◽  
Silicon Films ◽  
Starting Material ◽  
Near Surface ◽  
Silicon Thin Films ◽  
Crystallite Sizes

ABSTRACTIn an effort to enhance the electrical properties of silicon thin films, we have performed recrystallization experiments on a variety of amorphous silicon films using an excimer laser. The intense, pulsed UV produced by the laser (308nm, using XeCl gas) is highly absorbed by the amorphous material and thus provides intense localized heating in the near surface region. Two types of starting films were studied: plasma CVD a-Si:H and LPCVD a-Si. The subsequent modification produces crystallites whose structure and electrical characteristics vary due to starting material and laser scan parameters. The treated films have been characterized using Raman, x-ray diffraction, TEM, SIMS and transport measurements. The results indicate that crystallites nucleate in the surface region. The degree of crystallization near the surface increases dramatically as a function of deposited laser energy density and less so as a function of laser shot density. The hall mobility of the highly crystallized samples exhibit an increase of 2 orders of magnitude over the amorphous starting material. In the PECVD material, the rapid diffusion of hydrogen causes voids to be formed at intermediate laser energy densities and removal of film at higher energy densities. The LPCVD material withstands the high laser energies to produce well crystallized films with crystallite sizes greater then 1000Å.

Time-Resolved and Post-Irradiation Studies of the Interaction of High-Power Pulsed Microwave Radiation with Silicon

1986 ◽  
Vol 74 ◽  
Author(s):  
R. B. James ◽  
P. R. Bolton ◽  
R. A. Alvarez ◽  
R. E. Valiga ◽  
W. H. Christie
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Surface Damage ◽  
Threshold Value ◽  
Optical Measurements ◽  
Time Resolved ◽  
Near Surface ◽  
Reflected Power ◽  
Secondary Ion

AbstractWe have measured the microwave-induced damage to the near-surface region of silicon for 1.9-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 7.2 MW. Rectangular samples were irradiated in a test section of WR-284 waveguide that was filled with freon to a pressure of 30 psig. Incident, transmitted and reflected powers were monitored with directional couplers and fast diodes. The results of the time-resolved optical measurements show that the onset of surface damage is accompanied by a large increase in the reflected power. Examination of the irradiated surfaces shows that the degree of damage is greatest near the edges of the samples. Using secondary ion mass spectrometry to profile the implanted As, we find that the microwave pulses can melt the near-surface region of the material for pulse powers exceeding a threshold value.

Time-resolved optical studies of oxide-encapsulated silicon during pulsed laser melting

1988 ◽  
Vol 3 (3) ◽  
pp. 498-505 ◽  
Author(s):  
G. E. Jellison ◽  
D. H. Lowndes ◽  
J. W. Sharp
Keyword(s):  
Laser Annealing ◽  
Laser Energy ◽  
Threshold Energy ◽  
Pulsed Laser ◽  
Silicon Layer ◽  
Oxide Thickness ◽  
Time Resolved ◽  
Model Calculations ◽  
Near Surface ◽  
Surface Profiling

Nanosecond time-resolved reflectivity and ellipsometry experiments have been performed on (100) Si wafers encapsulated by 5.5–76.2 nm thick thermal oxides, using pulsed KrF (248 nm) laser energy densities sufficient to melt the Si beneath the oxide. Post-irradiation nulling ellipsometry, optical microphotography, and surface profiling measurements were carried out. It was found that the threshold energy density required to melt the Si varies with oxide thickness; this is explained primarily by the reflective properties of the oxide overlayer. The time-resolved reflectivity and ellipsometry measurements show that rippling of the SiO2 layer occurs on the 20–40 ns timescale and results in a decrease in specular reflectivity of the rippled silicon surface beneath. Optical model calculations suggest that pulsed laser annealing through a thick oxide layer results in a damaged near-surface silicon layer (∼ 30 nm thick); this layer contains defects that are probably responsible for the degraded performance of devices.

Excimer Laser Induced Modification of Teflon Surface into Silicon Carbide-Like

1991 ◽  
Vol 236 ◽  
Author(s):  
M. Okoshi ◽  
K. Toyoda ◽  
M. Murahara
Keyword(s):  
Silicon Carbide ◽  
Excimer Laser ◽  
Photochemical Reaction ◽  
Surface Region ◽  
Mixed Gas ◽  
Near Surface ◽  
Modification Process ◽  
Gas Atmosphere ◽  
Ft Ir ◽  
Arf Excimer Laser

AbstractA silicon carbide-like layer was produced in the near-surface region of teflon by irradiating with an ArF excimer laser in a SiH4 and B(CH3)3 mixed gas atmosphere. The pure photochemical reaction was employed in the modification process, and the defluorination of the surface was performed with boron atoms which were photodissociated from B(CH3)3. The CH3 radicals, also photodissociated, induced the dehydrogenation of SiH4 gas; which followed the production of SiHx radicals. The SiHx radicals and CH3 radicals which could not have induced the dehydrogenation of SiH4 were substituted for fluorine atoms of the surface. As a result, the surface was photomodified into silicon carbide. Chemical composition of the photomodified surface was inspected by the XPS and the ATR-FT-IR spectra measurement, and the bonding of the Si-CH3 radicals which traded off the reduction of the fluorine atoms was comfirmed. The Si/C composition ratio of the photomodified surface was 0.7.

Rapid Heating of Ion-Implanted Silicon by High-Power Pulsed Microwave Radiation

1988 ◽  
Vol 124 ◽  
Author(s):  
R. B. James ◽  
P. R. Bolton ◽  
R. A. Alvarez ◽  
W. H. Christie
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Light Emission ◽  
Electrical Breakdown ◽  
Rapid Heating ◽  
Surface Region ◽  
Time Resolved ◽  
Near Surface ◽  
Microwave Induced Plasma ◽  
Spatially Homogeneous ◽  
Secondary Ion

ABSTRACTWe have used 1.1-μs microwave pulses at a frequency of 2.856 GHz to rapidly heat the near-surface region of arsenic-implanted silicon. The samples were irradiated inside a WR-284 waveguide by single-pass TE10 traveling wave pulses. Post-irradiation studies show that surface melting occurs for incident pulse powers exceeding about 3 MW. Time-resolved measurements of the microwave reflectivity (R) show that there is an abrupt and large increase in R for microwave pulse powers greater than the melt threshold. Significant light emission was also observed from the test cell, which is most likely due to the relaxation of a microwave-induced plasma formed by electrical breakdown of gas. Using secondary ion mass spectrometry, we measured the depth profile of the implanted arsenic and found that the penetration of the melt front in the near-surface region is not spatially homogeneous over the silicon surface.

Pulsed Microwave Irradiation of Graphite/Epoxy Composites

1988 ◽  
Vol 124 ◽  
Author(s):  
R. B. James ◽  
P. R. Bolton ◽  
R. A. Alvarez
Keyword(s):  
Light Emission ◽  
Electrical Breakdown ◽  
Surface Region ◽  
Surface Damage ◽  
Sample Surface ◽  
Optical Measurements ◽  
Time Resolved ◽  
Near Surface ◽  
Reflected Power ◽  
Surface Decomposition

ABSTRACTWe have measured the microwave-induced damage to the near-surface region of a graphite/epoxy composite material for 1.1-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 8 MW. Rectangular samples were irradiated by single-pass TE10 traveling wave pulses inside a WR-284 waveguide, and in situ and post irradiation studies were performed to characterize the material modifications induced by the microwave pulses. The results of the time-resolved optical measurements in vacuo show that surface decomposition of the epoxy resin occurs for incident pulse powers exceeding 1.1 MW, and that the surface damage is accompanied by a large increase in the reflected microwave power. Simultaneous with the onset of surface decomposition, significant light emission from the sample and a large enhancement of the gas pressure in the test cell were observed. The large increments in both the reflected power and light emission are attributed to the formation of a plasma due to electrical breakdown of the gas at (or near) the sample surface.

Fabrication of p+/n Ultra Shallow Junctions (USJ) in silicon by excimer laser doping from spin-on glass sources

2004 ◽  
Vol 810 ◽  
Author(s):  
S. Coutanson ◽  
E. Fogarassy ◽  
J. Venturini
Keyword(s):  
Excimer Laser ◽  
Surface Region ◽  
Oxide Glass ◽  
Near Surface ◽  
Laser Doping ◽  
Dopant Incorporation ◽  
Ultra Shallow Junctions ◽  
20 Nm ◽  
Short Time ◽  
Dopant Source

ABSTRACTIn this work was investigated a simple laser doping method employing doped oxide glass films as dopant source (up to 2.1021cm−3) which are deposited onto silicon by the spin coating technique. Both short (20 ns) and long (200 ns) pulse duration excimer laser beams were used to deposit a large amount of energy in a short time onto the near-surface region. Under suitable conditions, the irradiation leads to surface melting and dopant incorporation by liquid phase diffusion from the surface. Boron distribution profiles in the two pulses duration regimes were studied as well as their electrical properties, and the junction formation of less than 20 nm in depth was demonstrated.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

The Effects of Ion Implantation on the Surface Features of Inconel 600

1985 ◽  
Vol 43 ◽  
pp. 288-289
Author(s):  
John D. Rubio
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Nuclear Power ◽  
Power Plants ◽  
Surface Region ◽  
Selective Dissolution ◽  
Boundary Region ◽  
Near Surface ◽  
Inconel 600 ◽  
Steam Generator Tubing

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.

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