摘要:

The ultraviolet and visible emission spectra from excimer laser‐produced silicon plasmas were studied and the ablation rate measured as a function of laser energy density and wavelength. A spectroscopic investigation of the laser‐produced plasma showed Si i, Si ii, and Si iiispectral lines with higher laser intensity causing a higher degree of ionization in the plasma. Both time‐integrated and time‐resolved spectroscopic studies showed electronic transitions superimposed on a weak continuum over the entire range from 250 to 640 nm. The photoablation rate of Si was independent of laser wavelength (193 or 248 nm), and had an energy density threshold of ≊1.3 J/cm2. The threshold was almost independent of the buffer gas pressure between vacuum and 1000 Torr. These results are described in the framework recently developed for excimer laser ablation of metals.

ISSN:1071-1023    

DOI:10.1116/1.583505

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

SiO2has been bombarded by 3 keV Ar+ions under simultaneous exposure to a thermal beam of Cl2or XeF2. Mass spectra and time‐of‐flight distributions of the sputtered species have been measured. It is observed that during XeF2exposure the sputtering yield of SiO2is enhanced with a factor of 2.3. After ionizing the neutral ejected Si species, we have detected SiF+x(x=0–4) and SiOF+y( y=0–2). The kinetic energy distributions of these particles indicate that the newly formed species have been bound loosely to the lattice and that they are sputtered predominantly by a collision cascade mechanism. The results are explained by assuming that adsorbed F atoms are mixed into subsurface layers in which Si–F bond formation takes place. Hardly any chemical enhancement of the sputtering yield of SiO2is observed when Cl2is added. In this case the Si species are detected as SiCl+xand SiOCl+y(x, y=0–2). The chlorine peak (Cl+) is an order of magnitude higher. The kinetic energy distribution of Cl shows that most of the chlorine is in the lattice chemically unbound. From the measurements it is concluded that the heat of formation determines that in the collision cascade Si–F bonds are formed while Si–Cl bonds are not. Differences in the enhancement of the sputtering yield between silicon and SiO2can also be explained by differences in heat of formation.

ISSN:1071-1023    

DOI:10.1116/1.583506

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

Ion beam simulation techniques are used to study fluorocarbon residue formation and substrate composition and structure modifications of silicon by CHF3plasma environment. Fluorocarbon residues are shown to grow by direct ion incorporation or ion activated growth processes in ion beams over the energy range 50–1000 eV. At ion energy>150 eV concurrent sputtering of the overlayer film results in a steady state film thickness of ∼30 Å, relatively independent of ion energy. Films are fluorine deficient, with C/F ratio of 1–3 depending on ion energy, dose, and film thickness. Energetic ion (300 eV) penetration of the film results in continuous Si etching and substantial substrate modification. For 560 eV ion energy an ion‐mixed interfacial layer of approximately 25 Å thickness is produced which contains substantial O, C, and F. A deeper (>150 Å) damaged layer is observed due to H+implantation. Removal of overlayer films and interfacial layers by standard cleaning procedures is addressed.

ISSN:1071-1023    

DOI:10.1116/1.583507

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

Plasma etching of silicon with H2and Cl2was simulated with mixtures of H2, Cl2, and SiCl4. The gas phase chemistry was elucidated by varying power and pressure. The cross sections for production of H (3p2P) atoms were probed through the emission response to pressure variations. Addition of rare gases to a hydrogen plasma identified qualitatively major energy transfer paths between the rare gas metastables and the H2/H system. We conclude that dissociation of hydrogen molecules and excitation of hydrogen atoms are separate electron impact collisional events that constitute the main excitation route in a hydrogen plasma. We find further that the role of metastable H atoms in the 2s2Sstate at 10.19 eV is minor, and that the direct dissociative excitation in a single electron impact at 16.57 eV is insignificant. The occurrence of state specific collisional energy exchange has limiting consequences for any actinometric method.

ISSN:1071-1023    

DOI:10.1116/1.583508

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The Auger electron spectroscopy sputter depth profiling technique has been used to evaluate the protective efficiency of ultrathin overlayers of As (∼25 Å) and GaAs (25 Å) against air exposure damaging effect of AlxGa1−xAs (x=0.3) epitaxial layers. It is shown that the As adsorbed overlayer is only partially effective to protect AlxGa1−xAs surface for a short air exposure. The surface of this reactive material can be more efficiently protected by GaAs, even for a very thin overlayer (25 Å). Results dealing with the effects of air and H2annealings on the AlxGa1−xAs surface are also reported. They confirm the Ga segregation at the AlxGa1−xAs surface recently reported [Stalletal., J. Vac. Sci. Technol. B3, 524 (1985) and Massiesetal.,ibid.3, 613 (1985)].

ISSN:1071-1023    

DOI:10.1116/1.583509

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

HgTe–CdTe superlattices were grown by molecular beam epitaxy on GaAs(100) substrates with CdTe buffer layers. The large (14.6%) lattice mismatch between CdTe and GaAs is relieved by a two‐dimensional array of misfit dislocations with a period of 3.1 nm. X‐ray diffraction, infrared transmittance, and Hall effect measurements are reported for thick (>5 μm) single crystalline superlattices.

ISSN:1071-1023    

DOI:10.1116/1.583510

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The growth of high quality GaAs and AlGaAs using the molecular beam epitaxy (MBE) technique requires that all of the components of the system be kept very clean, especially the source materials (Ga, As, and Al), the crucibles, and the furnaces since they are at high temperatures during the growth of the material. The crucibles, made of pyrolytic boron nitride (PBN), are used after a cleaning procedure that consists of a 1 h heat treatment at 1600 °C in a vacuum of approximately 5×10−9Torr or better. While this cleaning procedure has been used extensively, there have been no reported studies of the effectiveness of this procedure or its effect on the crucible. We have used mass spectrometry, AES, SIMS, XPS, and a modification of the LECO technique to study both baked and unbaked crucibles. In this paper we demonstrate that the cleaning procedure does remove impurities from the crucible, especially carbon. We also demonstrate that the cleaning procedure does not decompose the surface of the crucible as is commonly believed and that the recently observed dark striations on the interior of some of the crucibles after the bakeout are due to a physical restructuring of the surface and a possible local segregation of boron and not due to surface segregation of impurities such as carbon. We also present the first report of e‐beam induced decomposition of boron nitride.

ISSN:1071-1023    

DOI:10.1116/1.583511

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

In the present work, we have applied Raman scattering to study the damage produced by etching GaAs with inert and reactive gas plasmas. (AIP)

ISSN:1071-1023    

DOI:10.1116/1.583512

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.583513

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The increases in the packing density and the resulting shrinkage of the silicon integrated circuit dimensions led to the investigation and successful application of the deposited refractory silicide layers as the gate and interconnection metallization. The continued shrinking of the device dimensions has now turned attention to further lowering of the resistance at the gate level and to finding a contact metallization for the shallow junctions. Although refractory metals are being considered for the former, self‐aligned silicides of cobalt, titanium, platinum, and nickel offer the possibility of satisfying both the gate and interconnection and contact metallization requirements. This paper will review the present status of the refractory silicide and refractory metal technologies and compare them with the upcoming self‐aligned silicide technology.

ISSN:1071-1023    

DOI:10.1116/1.583514

出版商:American Vacuum Society    

年代:1986

数据来源: AIP