Polycrystalline Silicon Layers for Shallow Junction Formation: Phosphorus Diffusion from In Situ Spike-Doped Chemical Vapor Deposited Amorphous Silicon

1994 ◽  
Vol 343 ◽  
Author(s):  
D. Krüger ◽  
J. Schlote ◽  
W. Röpke ◽  
R. Kurps ◽  
Ch. Quick
Keyword(s):  
Amorphous Silicon ◽  
Structural Changes ◽  
Silicon Layer ◽  
Chemical Vapor ◽  
Heat Treatments ◽  
Si Substrate ◽  
Diffusion Limited ◽  
Pile Up ◽  
20 Nm

ABSTRACTShallow and lateral homogeneous delineated n+p-junctions were formed utilizing solid source diffusion from a deposited amorphous silicon layer with an in situ imbedded ultrathin phosphorus-rich zone. SIMS, AES, and TEM investigations were carried out to analyze the dopant behavior in correlation to morphological and structural changes during subsequent heat treatments. After heat treatments up to 950°C the layer remained flat, surface roughness was found to be less than 3 nm. Dopant pile up at the Si-layer/Si-substrate interface was observed and interpreted on the basis of segregation phenomena. From the time dependence the P segregation-pile-up was found to be diffusion limited except for a small starting period. The dopant concentration in the Si-substrate drops down over more than 2 orders of magnitude in a thickness range less than 20 nm.

Deposition and Crystallisation Behaviour of Amorphous Silicon Thin Films Obtained by Pyrolysis of Disilane Gas at Very Low Pressure

1994 ◽  
Vol 345 ◽  
Author(s):  
T. Kretz ◽  
D. Pribat ◽  
P. Legagneux ◽  
F. Plais ◽  
O. Huet ◽  
...  
Keyword(s):  
Activation Energy ◽  
Growth Rate ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Electrical Conductance ◽  
Chemical Vapor ◽  
Crystalline Fraction ◽  
Silicon Thin Films ◽  
Crystallisation Behaviour

AbstractHigh purity amorphous silicon layers were obtained by ultrahigh vacuum (millitorr range) chemical vapor deposition (UHVCVD) from disilane gas. The crystalline fraction of the films was monitored by in situ electrical conductance measurements performed during isothermal annealings. The experimental conductance curves were fitted with an analytical expression, from which the characteristic crystallisation time, tc, was extracted. Using the activation energy for the growth rate extracted from our previous work, we were able to determine the activation energy for the nucleation rate for the analysed-films. For the films including small crystallites we have obtained En ∼ 2.8 eV, compared to En ∼ 3.7 eV for the completely amorphous ones.

Hydrogen Release and Si-N Bond-Healing Infrared Study of Rapid Thermal Annealed Amorphous Silicon Nitride Thin Films

1995 ◽  
Vol 398 ◽  
Author(s):  
P. Santos-Filho ◽  
G. Stevens ◽  
Z. Lu ◽  
K. Koh ◽  
G. Lucovsky
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Gas Flow ◽  
Structural Changes ◽  
Thermal Dissociation ◽  
Chemical Vapor ◽  
Hydrogen Release ◽  
Ex Situ ◽  
Infrared Study ◽  
Amorphous Silicon Nitride

ABSTRACTWe address aspects of hydrogen bonding and its thermal evolution in amorphous Silicon nitride films grown by Remote Plasma Enhanced Chemical Vapor Deposition (RPECVD) from SiH4 and NH3 (or ND3) source gases. Rapid Thermal Annealing (RTA) decreases the Si-H(D) and SiN-H(D) bond populations. The hydrogen bonds break, and H2 (HD, D2) forms and evolves from the film with the heat treatment. This molecular hydrogen release is accompanied by Si- and N- bond healing as detected by a SiN infra red stretch mode signal gain. The ex-situ RTA experiment temperatures ranged from 400 °C to 1200 °C, in 100 °C steps and the film structural changes were monitored by Fourier Transform Infrared spectroscopy (FTIR) after each incremental anneal. Gas flow ratios R=NH3/SiH4 > 2 produced films in which SiN-H(D) bonds dissociated, and a gas desorption rate equation estimated an activation energy barrier of Ea = 0.3 eV. The release of hydrogen from the films in the form of H2 (D2) and ammonia radicals was detected by mass spectrometry and is shown here. The re-bonding of nitrogen to silicon upon thermal dissociation of hydrogen's is consistent with the improvement of the electrical properties of a-SiN:H films following RTA treatment.

Stress Induced During the Solid-phase Crystallization of Amorphous Silicon Deposited by LPCVD

1995 ◽  
Vol 403 ◽  
Author(s):  
T. Mohammed-Brahim ◽  
K. Kis-Sion ◽  
D. Briand ◽  
M. Sarret ◽  
F. Lebihan ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Solid Phase ◽  
Chemical Vapor ◽  
In Situ Monitoring ◽  
Crystallization Time ◽  
Solid Phase Crystallization ◽  
Pressure Chemical ◽  
Hall Effect Measurements ◽  
Deposition Techniques

AbstractThe Solid Phase Crystallization (SPC) of amorphous silicon films deposited by Low Pressure Chemical Vapor phase Deposition (LPCVD) using pure silane at 550'C was studied by in-situ monitoring the film conductance. The saturation of the conductance at the end of the crystallization process is found transient. The conductance decreases slowly after the onset of the saturation. This degradation is also observed from other analyses such as ellipsometry spectra, optical transmission and Arrhenius plots of the conductivity between 250 and 570K. Hall effect measurements show that the degradation is due to a decrease of the free carrier concentration n and not to a decrease of the mobility. This indicates a constant barrier height at the grain boundaries. The decrease of n is then due to a defect creation in the grain. Hence, whatever the substrate used, an optimum crystallization time exists. It depends on the amorphous quality film which is determined by the deposition techniques and conditions and on the crystallization parameters.

Formation and Crystallization of Amorphous Silicides at the Interface Between Thin Metal and Amorphous Silicon Films

1982 ◽  
Vol 18 ◽  
Author(s):  
S. R. Herd ◽  
K. Y. Ahn ◽  
K. N. Tu
Keyword(s):  
Amorphous Silicon ◽  
Amorphous Phase ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
Diffraction Peak ◽  
Gold Films ◽  
Cubic Form ◽  
No Formation ◽  
Transmission Electron

We investigated the interaction of extremely thin (less than 10 nm) crystalline gold and rhodium films with amorphous silicon by transmission electron microscope in situ annealing. In thin Au/Si bilayers an amorphous phase with a diffraction peak at d ≂ 0.226 nm is formed by thermal annealing between 150 and 200 °C. Depending on the thickness and composition, silicon sputtered onto thin gold films leads to the formation of a layer of amorphous silicon and a partially amorphous Au-Si layer during deposition. The silicon layer crystallizes by itself at temperatures as low as 150 °C, and at 300 °C the amorphous Au–Si layer crystallizes into a metastable gold silicide (for silicon-rich compositions). In Rh/Si bilayers an amorphous Rh–Si phase is formed by annealing to 300 °C and can be detected by electron diffraction for a rhodium thickness of less than 5 nm and compositions with more than 50% Si if completely reacted. Above 300 °C the amorphous Rh-Si crystallizes preferentially in the cubic form of RhSi for intermediate silicon compositions and in the orthorhombic form of RhSi for high silicon compositions. Excess amorphous silicon is not found to have a lowered crystallization temperature when in contact with the amorphous Rh-Si alloy, and crystalline silicon is only observed above 730 °C together with the cubic and/or orthorhombic RhSi. In Rh/Si bilayers with a thicker rhodium layer, no formation of an amorphous phase was observed on annealing; instead crystalline Rh2Si forms during annealing above 300 °C.

Effect of NH3 Plasma Treatment on Etching of Ti During Ticl4-Based Tin CVD Processes

1998 ◽  
Vol 514 ◽  
Author(s):  
M. E. Gross ◽  
E. Coleman ◽  
K. Ohto
Keyword(s):  
Integrated Circuit ◽  
Chemical Vapor ◽  
Ex Situ ◽  
Si Substrate ◽  
Barrier Films ◽  
Series Of Experiments ◽  
Pre Treatment ◽  
Initial Deposition ◽  
Ti Films

ABSTRACTIntegration of a TiCl4-based chemical vapor deposition (CVD) process for TiN barrier films with Ti underlayers for sub-micron integrated circuit metallization stacks exposes the Ti film to TiCl4 and NH3 adducts of TiCl4 that may etch the Ti in addition to depositing TiN. In this paper we report results of studies on the interactions of TiCl4 with ex situ PVD Ti films during the CVD TiN process. Deposition of TiN on Ti/SiO2/Si using a onestep 650°C process shows evidence of significant etching of the underlying Ti. A two-step process using a reduced TiCl4 flow for the initial deposition reduced the amount of etching but for Ti films over 200Å thick there was significant non-uniformity and peeling at the Ti/SiO2 interface. Pre-treatment of the Ti surface in situ with a 500W, 450 kHz NH3 plasma for 20–60 sec. leads to formation of TiN0.3, which shows a slight protective effect against etching. The same series of experiments with Ti deposited on Si reveals no etching, owing to reaction of the Ti with the Si substrate to form etch-resistant silicides. These results suggest that integration of a TiCl4-based CVD TiN process with an underlying Ti layer may be undesirable unless the surface of the Ti is protected against etching.

Controlled Growth of Amorphous Silicon Nanowires Via a Solid-Liquid-Solid (SLS) Mechanism

1999 ◽  
Vol 581 ◽  
Author(s):  
H. F. Yan ◽  
Y. J. Xing ◽  
Q. L. Hang ◽  
D. P. Yu ◽  
J. Xu ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Silicon Nanowires ◽  
Whisker Growth ◽  
Average Diameter ◽  
Si Substrate ◽  
Large Area ◽  
Vapor Liquid Solid ◽  
Silicon Source ◽  
20 Nm ◽  
Solid Liquid

ABSTRACTAmorphous silicon nanowires (a-SiNW's) with average diameter around 20 nm were synthesized at about 950° C under an Ar/H2 atmosphere on large area of a (11) Si substrate without supplying any gaseous or liquid Si sources. The Si substrate, deposited with a layer of Ni of about 40 nm thick, served itself as a silicon source for the growth of the a-SiNWs. Different from the well-known vapor-liquid-solid (VLS) for conventional whisker growth, it was found that growth of the a-SiNWs was controlled by a solid-liquid-solid mechanism, which is analogous to the VLS model.

Microstructural Observation of Focused Ion Beam Modification of Ni Silicide/Si Thin Films

1996 ◽  
Vol 439 ◽  
Author(s):  
Miyoko Tanaka ◽  
Kazuo Furuya ◽  
Tetsuya Saito
Keyword(s):  
Structural Changes ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Dark Field ◽  
In Situ Tem ◽  
Si Substrate ◽  
Ion Beam Modification ◽  
Surrounding Matrix ◽  
Transmission Electron

AbstractFocused ion beam (FIB) irradiation of a thin Ni2Si layer deposited on a Si substrate was carried out and studied using an in-situ transmission electron microscope (in-situ TEM). Square areas on sides of 4 by 4 and 9 by 9 μm were patterned at room temperature with a 25keV Ga+-FIB attached to the TEM. The structural changes of the films indicate a uniform milling; sputtering of the Ni2Si layer and the damage introducing to the Si substrate. Annealing at 673 K results in the change of the Ni2Si layer into an epitaxial NiSi2 layer outside the FIB irradiated area, but several precipitates appear around the treated area. Precipitates was analyzed by energy dispersive X-ray spectroscopy (EDS). Larger amount of Ni than the surrounding matrix was found in precipitates. Selected area diffraction (SAD) patterns of the precipitates and the corresponding dark field images imply the formation of a Ni rich silicide. The relation between the FIB tail and the precipitation is indicated.

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