摘要:

The thickness uniformity of a spin‐cast film is governed by the air flow through the spin coater, particularly the boundary layer flow above the surface of the spinning wafer, which controls solvent evaporation from the dry film. Laser Doppler velocimetry (LDV) and hot wire anemometry (HWA) are used to map the flow field throughout an industrial spin coater and to study flow instabilities in the boundary layer for various combinations of wafer spin speed and exhaust flow rate. The flow field measured by LDV compares well with a numerical simulation of laminar, axisymmetric, and steady air flow throughout the coating bowl. However, Ekman spiral flow instabilities of both type I (positive spiral angle) and type II (negative spiral angle) were found by HWA in the boundary layer near the surface of the spinning wafer. The type‐II spirals form at Reynolds number in the range 2000–2500 and the type‐I spirals form at Reynolds number in the range 80 000–85 000. It is the type‐II spirals that are responsible for disrupting the air flow in the boundary layer flow and that cause nonuniform drying of spin‐cast films. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358751

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Experiments have been performed to investigate voltage scaling in a plasma opening switch (POS) as the radius of the cathode is varied. Two different opening switch configurations have been used. In one of these the anode and cathode are simple coaxes with constant radii. In the other, there is an increase in anode radius immediately downstream of the switch. It is found that for all the data the peak voltage of the POS follows a simple scaling law with cathode radius for short conduction times, but that as conduction time is increased the two sets of data diverge. The configuration with the increased anode radius shows a marked improvement in operating voltage at long conduction times as compared to the simple hardware, however, the data from each set of hardware continue to follow the derived scaling law for all conduction times observed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358752

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present the results of a new computer simulation model developed to study the propagation of electromagnetic waves in a dielectric medium in both the linear and nonlinear regimes. The model is constructed by combining a microscopic model used in the semi‐classical approximation for the dielectric media and a particle model developed for the plasma simulations. It is shown that the model may be useful for studying linear and nonlinear wave propagation in the dielectric media. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358753

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The structural properties of sputtered CoCrPt at levels of 0.1, 0.3, 0.5, and 1 kW sputtering power were measured by x‐ray diffraction, small‐angle x‐ray scattering (SAXS), x‐ray absorption fine structure, and transmission electron microscope (TEM). XRD indicated a continuous increase in the intensity of the peak of hcp(002) orientation, as sputtering power increases. SAXS, on the other hand, in the range of 0.5°–3°, indicated the presence of scattering center for the 0.1 and 0.3 kW samples alone, not for the others. Similarly discontinuous were the spectra produced by x‐ray absorption near‐edge structure of CoKedge. Only the 0.1 kW sample showed a spectrum different from the others. This means that the electronic state for 0.1 kW sample is different from that for the others. TEM observation, carried out to examine the structural morphology, indicated a clear small‐grain structure for the 0.1 kW sample, less clearly defined grains for the 0.3 kW sample, and no observable grains for the others after chemical etching pretreatment. The grain size for the 0.1 and 0.3 kW samples are about 100 and 200 A˚, respectively. The grain is considered to consist of a Co‐rich boundary and Pt‐rich inside region from the chemical analysis of the solvent. The sputtering power dependence of the structural properties is able to be explained consistently as follows. As the sputtering power decreases, the segregated grain structure appears and affects SAXS. When the segregated grain size becomes smaller, it affects the electronic state. The different sputtering power dependence of structural properties comes from the different correlation lengths included in the measurements. Therefore, to understand the relationship between the magnetic and structural properties, structural investigation should include various range orders. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358754

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Damage and strain produced in a 370‐nm‐thick strained epitaxial Ge0.10Si0.90film on Si(100) by irradiation with 320 keV28Si+ions at fixed temperatures ranging from 40 to 150 °C and for doses from 1 to 30×1014/cm2have been measured by MeV4He channeling spectrometry, transmission electron microscopy, and high‐resolution x‐ray diffractometry. The ion energy was chosen so that the maximum damage created by irradiation occurs very near the GeSi‐Si interface. For all temperatures, the retained damage and the perpendicular strain induced by the irradiation are significantly greater in the GeSi epilayer than in the Si substrate. For all doses the retained damage and the induced perpendicular strain become small above 100 °C. Both rise nonlinearly with increasing ion dose. They are related to each other differently in GeSi than in bulk Si or Ge irradiated at room temperature. Postirradiation furnace annealing can remove a large portion of the induced damage and strain for nonamorphized samples. Amorphized samples regrow by solid‐phase epitaxy after annealing at 550 °C for 30 min; the regrown GeSi is, however, highly defective and elastically relaxed. A consequence of this defectiveness is that irradiation‐induced amorphization in metastable GeSi is undesirable for applications where good crystalline quality is required. Ion implantation above room temperature can prevent amorphization. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358755

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Radiation‐induced defects in a new second harmonic generation material, lithium vanadate single crystal, have been studied by electron paramagnetic resonance (EPR) and optical absorption measurements. EPR detects two intense signals due to intrinsic O−and impurity‐associated CO−3trapped‐hole centers at 77 K, but no such signal in the case of trapped‐electron centers. The EPR signal of impurity Fe3+ions is suppressed by 77 K irradiation. Low‐temperature irradiation produces three optical absorption bands peaking at 3.14, 2.0, and 1.56 eV. It has been concluded that some of the free electrons produced by irradiation are trapped by Fe3+ions at low temperatures. After annealing at room temperature all the optical absorption bands disappear, although the EPR signals of CO−3trapped‐hole centers and unidentified electron‐type centers atg=1.96 remain stable up to 330 K. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359541

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Results are presented on the ablation by 157 nm laser radiation of polytetrafluoroethylene (PTFE), polyimide, polyhydroxybutyrate (PHB), poly(methyl methacrylate) (PMMA), and poly(2‐hydroxyethyl methacrylate) with 1% of ethylene glycol dimethacrylate as a crosslinking monomer. Direct photoetching of PHB and undoped PTFE is demonstrated for laser fluences ranging from 0.05 to 0.8 J/cm2. The dependence of the ablation process on the polymer structure is analyzed, and insight into the ablation mechanism is gained from an analysis of the data using Beer–Lambert’s law and the kinetic model of the moving interface. Consideration of the absorbed energy density required to initiate significant ablation suggests that the photoetching mechanism is similar for all the polymers studied. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358756

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Low‐energy ion bombardment of the Ge(001)‐(2×1) surface produces surface point defects, which are detected and quantified usinginsitureflection high‐energy electron diffraction. Surface defect production rates are determined for a range of ion energies and ion masses. At low substrate temperatures (T≊−100 °C), copious production of surface defects is observed, with defect yields as high as 20–30 defects per ion for 500 eV Ar and Xe bombardment. The observed He surface defect yields exceed the surface yield predicted by binary collision simulations, indicating that defects created in the subsurface region migrate to the surface for these conditions. The observed surface defect yield is reduced at elevated substrate temperatures. Based on a simple model this reduction is attributed to surface recombination of point defects created within the same cascade. A constant surface defect yield is reached at temperatures greater than 100 °C which is consistent with the net defect production due to the vacancies left by sputtering. However, even at elevated temperatures, significantly larger populations of mobile point defects than can be accounted for by sputtering may reside transiently on the surface, which can modify the overall surface morphology. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358757

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This paper demonstrates that Kelvin probe force microscopy (KFM) is applicable to the characterization of semiconductor devices. The optimum operating conditions for KFM measurements are determined experimentally. Low potential deviation of less than several mV and high topographic resolution sufficient to display monolayer‐height steps were obtained at tip‐sample distances ranging from 40 to 60 nm. Potential distributions were measured on thin InGaAs resistors using KFM. The steep potential drops observed at the contact edges attributable to the contact resistance are verified by measuring the contact resistance using the transfer length method and the results of previously reported scanning tunneling potentiometry. The KFM results accurately explain the electrical properties of the metal/semiconductor interface. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358758

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using chemical‐vapor deposition nanodispersed silicon has been prepared in carbon at temperatures between 850 and 1050 °C. Samples with up to 11% atomic silicon in carbon show the same pregraphitic x‐ray‐diffraction pattern as those without silicon. X‐ray‐absorption spectroscopy shows that the silicon is bonded mostly to carbon neighbors and that large clusters of silicon are not found. It is believed that silicon atoms, or small clusters of a few silicon atoms, are located in regions of ‘‘unorganized carbon’’ which separate small regions of organized graphene layers. These materials may have application as electrode materials in advanced rechargeable lithium batteries. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358759

出版商:AIP    

年代:1995

数据来源: AIP