An Experimental Study on Laser Annealing of Thin Silicon Layers

A laser annealing technique directed toward producing single crystalline silicon on substrates is studied. In this paper the laser-induced melting of thin silicon films is studied experimentally. Direct heating of thin silicon layers on substrates is shown to produce a variety of different silicon melting patterns. A systematic study of these phase change phenomena has been performed. The important parameters are: (1) the laser beam power, (2) the laser beam intensity distribution, and (3) the speed of the translating silicon layer. Unstable silicon phase boundaries break up to form regions where solid and melt silicon coexist. Complicated silicon phase boundary patterns are shown. The experimental results showed the occurrence of organized patterns of alternating solid and liquid silicon stripes for two-dimensional heating distributions. Finally, temperature fields for the experimental operating conditions are calculated using an enthalpy model.

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Ultrafast carbothermal reduction of silica to silicon using a CO2 laser beam

Scientific Reports ◽

10.1038/s41598-020-78562-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Seok-Ho Maeng ◽

Hakju Lee ◽

Min Soo Park ◽

Suhyun Park ◽

Jaeki Jeong ◽

...

Keyword(s):

Carbon Black ◽

Laser Beam ◽

Carbothermal Reduction ◽

Gas Flow ◽

Crystalline Silicon ◽

Reduction Process ◽

Reaction Chamber ◽

Raman Shift ◽

Influence Of Process Parameters ◽

Laser Beam Intensity

AbstractWe report the extraction of silicon via a carbothermal reduction process using a CO2 laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown after laser beam irradiation for a few tens of seconds, and clear peaks of crystalline silicon were observed by Raman shift measurements, confirming the successful carbothermal reduction of silica. The influence of process parameters, including the laser beam intensity, radiation time, nitrogen gas flow in a reaction chamber, and the molar ratios of silica/carbon black of the mixture, on the carbothermal reduction process is explained in detail.

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Self-compression of two co-propagating laser pulse having relativistic nonlinearity in plasma

Laser and Particle Beams ◽

10.1017/s0263034617000787 ◽

2017 ◽

Vol 35 (4) ◽

pp. 722-729

Author(s):

S. Kumar ◽

P. K. Gupta ◽

R. K. Singh ◽

R. Uma ◽

R. P. Sharma

Keyword(s):

Laser Beam ◽

Pulse Width ◽

Pulse Compression ◽

Group Velocity Dispersion ◽

Refractive Index Profile ◽

Intense Laser ◽

Laser Beams ◽

Critical Parameters ◽

Beam Power ◽

Laser Beam Intensity

AbstractThe study proposes a semi-analytical model for the pulse compression of two co-propagating intense laser beams having Gaussian intensity profile in the temporal domain. The high power laser beams create the relativistic nonlinearity during propagation in plasma, which leads to the modification of the refractive index profile. The co-propagating laser beams get self- compressed by virtue of group velocity dispersion and induced nonlinearity. The induced nonlinearity in the plasma broadens the frequency spectrum of the pulse via self-phase modulation, turn to shorter the pulse duration and enhancement of laser beam intensity. The nonlinear Schrodinger equations were set up for co-propagating laser beams in plasmas and have been solved in Matlab by considering paraxial approximation. The propagation characteristics of both laser beams inside plasma are divided into three regions through the critical divider curve, which has been plotted between pulse width τ01 and laser beam power P01. Based on the preferred value of critical parameters, these regions are oscillatory compression, oscillatory broadening, and steady broadening. In findings, it is observed that the compression of the laser beam depends on the combined intensity of both beams, plasma density, and initial pulse width.

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The Recrystallization Depth Control of the Excimer-Laser-Recrystallized Poly-Crystalline Silicon Film

MRS Proceedings ◽

10.1557/proc-557-689 ◽

1999 ◽

Vol 557 ◽

Author(s):

Kee-Chan Park ◽

Kwon-Young Choi ◽

Jae-Hong Jeon ◽

Min-Cheol Lee ◽

Min-Koo Han

Keyword(s):

Laser Beam ◽

Excimer Laser ◽

Laser Annealing ◽

Silicon Oxide ◽

Crystalline Silicon ◽

Silicon Film ◽

Film Structure ◽

Excimer Laser Annealing ◽

Silicon Oxide Layer ◽

Thin Oxide Film

AbstractA novel method to control the recrystallization depth of amorphous silicon (a-Si) film during the excimer laser annealing (ELA) is proposed in order to preserve a-Si that is useful for fabrication of poly-Si TFT with a-Si offset in the channel. A XeCl excimer laser beam is irradiated on a triple film structure of a-Si thin native silicon oxide (~20Å)/thick a-Si layer. Only the upper a-Si film is recrystallized by the laser beam irradiation, whereas the lower thick a-Si film remains amorphous because the thin native silicon oxide layer stops the grain growth of the poly-crystalline silicon (poly-Si). So that the thin oxide film sharply divides the upper poly-Si from the lower a-Si.

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Real Time Monitoring Of The Optical Properties Of Cw Laser Annealed Silicon

MRS Proceedings ◽

10.1557/proc-1-133 ◽

1980 ◽

Vol 1 ◽

Author(s):

John F. Ready ◽

B. Thompson Mcclure ◽

Terry L. Brewer ◽

William L. Larson

Keyword(s):

Laser Beam ◽

Laser Annealing ◽

Crystalline Silicon ◽

Past History ◽

Implantation Dose ◽

Oscillatory Behavior ◽

Index Of Refraction ◽

Destructive Interference ◽

History Of ◽

Surface Reflectivity

ABSTRACTThe surface reflectivity of ion implanted silicon is a function of the entire past history of the material, including the nature of the implanted species and the implant dose. It is influenced by interference effects, arising from discontinuities in index of refraction at the surface and at the boundary between damaged and undamaged material. The reflectivity may be either higher or lower than that of the unimplanted silicon. As the crystalline silicon regrows from below, the reflectivity changes because of variable constructive or destructive interference. This paper describes monitoring of the surface reflectivity during continuous laser annealing. The beam from a continuous argon ion laser is scanned in a raster pattern over the silicon surface. The surface reflectivity for a HeNe laser beam is monitored as a function of time during crystalline regrowth. The reflectivity contains an oscillatory component which arises because of changes in interference due to the decreasing thickness of the noncrystalline layer. The oscillatory behavior produces a signature characteristic of the annealing. The reflectivity monitoring technique is useful for investigating the influence of parameters such as the spatial profile of the laser beam and the implantation dose on the annealing characteristics. The results are correlated with measurements of the depth profile of the implanted ions, as revealed by anodic oxidation and stripping.

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Faster Quenching by Silicon Pulsed Laser Annealing Under Water

MRS Proceedings ◽

10.1557/proc-74-129 ◽

1986 ◽

Vol 74 ◽

Cited By ~ 1

Author(s):

A. Polman ◽

S. Roorda ◽

S. B. Ogale ◽

F. W. Saris

Keyword(s):

Laser Pulse ◽

Laser Annealing ◽

Crystalline Silicon ◽

Diffusion Theory ◽

Pulsed Laser ◽

Silicon Layer ◽

Water Layer ◽

Amorphous Layer ◽

Pulsed Laser Annealing ◽

Novel Method

AbstractA novel method of pulsed laser processing of ion-implanted silicon is presented, in which samples are irradiated in water ambient. The water layer in contact with the silicon during irradiationh as a considerable influence on melting and solidificationd ynamics. Still, perfect epitaxy of a thin amorphous layer can be obtained using this method.For epitaxy to occur on a sample irradiated under water, 40 % more absorbed energy is necessary than for a sample irradiated in air. This indicates the occurrence of a considerable heat-flow from the silicon into the water layer during the laser pulse. From impurity redistribution after irradiation it is found that by processing a sample under water liquid-phase diffusion is reduced. Diffusion theory arguments indicate that this can be due to a reduction in total melt duration by about afactor 2–3. This can be due to faster cooling of the liquid silicon layer after the laser pulse whereas the melt-in time might be influenced as well. As a consequence, shallower impurity profiles can be obtained in crystalline silicon. No oxygen incorporation is detected and the surface morphology is not disturbed using this new process.

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Behavior of contact-silicided TFSOI gate structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172036 ◽

1994 ◽

Vol 52 ◽

pp. 860-861

Author(s):

N. David Theodore ◽

Juergen Foerstner ◽

Peter Fejes

Keyword(s):

Semiconductor Device ◽

Series Resistance ◽

Field Effect Transistors ◽

Silicon Layer ◽

Device Fabrication ◽

Silicon On Insulator ◽

Continuous Layer ◽

Buried Oxide ◽

Device Structures ◽

Thin Silicon

As semiconductor device dimensions shrink and packing-densities rise, issues of parasitic capacitance and circuit speed become increasingly important. The use of thin-film silicon-on-insulator (TFSOI) substrates for device fabrication is being explored in order to increase switching speeds. One version of TFSOI being explored for device fabrication is SIMOX (Silicon-separation by Implanted OXygen).A buried oxide layer is created by highdose oxygen implantation into silicon wafers followed by annealing to cause coalescence of oxide regions into a continuous layer. A thin silicon layer remains above the buried oxide (~220 nm Si after additional thinning). Device structures can now be fabricated upon this thin silicon layer.Current fabrication of metal-oxidesemiconductor field-effect transistors (MOSFETs) requires formation of a polysilicon/oxide gate between source and drain regions. Contact to the source/drain and gate regions is typically made by use of TiSi2 layers followedby Al(Cu) metal lines. TiSi2 has a relatively low contact resistance and reduces the series resistance of both source/drain as well as gate regions

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Formation of Nanocrystalline Silicon in Tin-Doped Amorphous Silicon Films

Ukrainian Journal of Physics ◽

10.15407/ujpe65.3.236 ◽

2020 ◽

Vol 65 (3) ◽

pp. 236

Author(s):

R. M. Rudenko ◽

O. O. Voitsihovska ◽

V. V. Voitovych ◽

M. M. Kras’ko ◽

A. G. Kolosyuk ◽

...

Keyword(s):

Amorphous Silicon ◽

Crystalline Silicon ◽

Solid Phase ◽

Nanocrystalline Silicon ◽

Recrystallization Temperature ◽

Nanocrystalline Phase ◽

Silicon Phase ◽

Silicon Nanocrystallites ◽

Lower Temperature ◽

Two Stages

The process of crystalline silicon phase formation in tin-doped amorphous silicon (a-SiSn) films has been studied. The inclusions of metallic tin are shown to play a key role in the crystallization of researched a-SiSn specimens with Sn contents of 1–10 at% at temperatures of 300–500 ∘C. The crystallization process can conditionally be divided into two stages. At the first stage, the formation of metallic tin inclusions occurs in the bulk of as-precipitated films owing to the diffusion of tin atoms in the amorphous silicon matrix. At the second stage, the formation of the nanocrystalline phase of silicon occurs as a result of the motion of silicon atoms from the amorphous phase to the crystalline one through the formed metallic tin inclusions. The presence of the latter ensures the formation of silicon crystallites at a much lower temperature than the solid-phase recrystallization temperature (about 750 ∘C). A possibility for a relation to exist between the sizes of growing silicon nanocrystallites and metallic tin inclusions favoring the formation of nanocrystallites has been analyzed.

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Short Channel Poly-Si TFT with Single Grain Boundary by Excimer Laser Annealing on Al-masked a-Si Layer

MRS Proceedings ◽

10.1557/proc-715-a7.8 ◽

2002 ◽

Vol 715 ◽

Author(s):

Sang-Hoon Jung ◽

Jae-Hoon Lee ◽

Min-Koo Han

Keyword(s):

Grain Boundary ◽

Laser Annealing ◽

Thin Film Transistor ◽

High Mobility ◽

Silicon Layer ◽

Silicon Thin Film ◽

Short Channel ◽

Excimer Laser Annealing ◽

Boundary Density ◽

Single Grain

AbstractA short channel polycrystalline silicon thin film transistor (poly-Si TFT), which has single grain boundary in the center of channel, is reported. The reported poly-Si TFT employs lateral grain growth method through aluminum patterns, which acts as a selective beam mask and a lateral heat sink during the laser irradiation, on an amorphous silicon layer. The electrical characteristics of the proposed poly-Si TFT have been considerably improved due to grain boundary density lowered. The reported short channel poly-Si TFT with single grain boundary exhibits high mobility as 222 cm2/Vsec and large on/off current ratio exceeding 1 × 108.

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