摘要:

In this article, a force microscope using a twin‐path (common‐path) laser interferometer is presented. The interferometer was developed for the displacement detection of a small cantilever. Since the two interfering beams were very close to each other, the perturbation caused by the environmental disturbances were minimized. The optical path difference between the two beams was easily adjusted by the moire effect of the gratings. The vibrational amplitude of 10−3nm was measured under the resonance conditions of the tungsten lever. The drift rate of the interference signal was less than 10−3nm/s. An etched‐resist coated with thin gold film was imaged by using electrostatic forces under the conditions of ac mode operation.

ISSN:1071-1023    

DOI:10.1116/1.586301

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The thermal faceting of TiO2(001) rutile was studied in ultrahigh vacuum using scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction (LEED). The predominant facet planes observed by STM after annealing to 510 °C were (011) and stepped (011), in agreement with the LEED work of Firment. The step structure on (011) planes is indicative of facet growth by surface migration. A smaller number of (114) and (111) planes were observed, in agreement with the work of Firment and Tait and Kasowski. Facet structures resembling those proposed by Kurtz, based on electron simulated desorption ion angular distribution results, were observed for the (011) planes.

ISSN:1071-1023    

DOI:10.1116/1.586393

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The growth and the atomic structure of the Ge on the Si(111)‐((3)1/2×(3)1/2)R30° surface are investigated by scanning tunneling microscopy. The coexistence of the ((3)1/2×(3)1/2)R30° and thec(2×4) reconstruction at the Si‐substrate is discussed. Germanium on silicon, usually indistinguishable from the silicon is identified on the boron induced ((3)1/2×(3)1/2)R30° surface using the difference in reconstruction of the substrate and epitaxial material. The germanium deposit shows a dimer adatom stacking fault‐like structure while the substrate still remains ((3)1/2×(3)1/2)R30° reconstructed. A significant boron diffusion is only observed after annealing at 480 °C, which converts the island surface into a ((3)1/2×(3)1/2)R30° reconstruction.

ISSN:1071-1023    

DOI:10.1116/1.586292

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

An experimental study of damping and frequency of vibrating small cantilever beams in their lowest eigenstate is presented. The cantilever beams are fabricated from monocrystalline silicon by means of micromachining methods. Their size is a few millimeters in length, a few 100 μm in width, and a few 10 μm in thickness. Damping and resonance frequency are studied as a function of the ambient pressurep(1–105Pa) and the geometry of the beam. The purpose of this research was to obtain design rules for sensors employing vibrating beams. The analysis of the experimental results in terms of a semiqualitative model reveals that one can distinguish three mechanisms for the pressure dependence of the damping: viscous, molecular, and intrinsic. For viscous damping a turbulent boundary layer dominates the damping at high pressures (≊105Pa), while at smaller pressure laminar flow dominates. In the latter region, this leads to a plateau for the quality factorQand in the former toQα √p. The pressurepcat which the transition from laminar flow dominated damping to turbulent flow dominated damping occurs depends on the geometry of the beams.pcis independent on the length and decreases with both, the width and the thickness of the beams.

ISSN:1071-1023    

DOI:10.1116/1.586300

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

We have developed an unconventional approach to down‐stream plasma etching: only a small area of the substrate is exposed to the low pressure, reactive gaseous environment. The remainder of the substrate is outside the miniature plasma chamber, providing physical access for probing apparatus. Etch rates of 6 μm/h were obtained. The process can be especially useful wheninsitumonitoring of the effects of etching is required. Using this process, we improved the responsivity of a semiconductor optical detector deposited on top of an optical waveguide. This was accomplished by monitoring the transmitted intensity of light in an integrated optical waveguide while etching a thin semiconductor film covering a small region of the waveguide.

ISSN:1071-1023    

DOI:10.1116/1.586347

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Particle contamination on silicon wafers exposed to a SF6/Ar plasma is examined as a function of five critical plasma parameters using response surface methodology. Plasma parameters explored are 13.56 MHz rf power, pressure, process gas flow rate, 100 KHz wafer electrode power, and etch time. The experiment is conducted in a Tegal MCR‐1 single wafer reactor operated in the triode mode. Particle count is found to increase linearly as a function of 13.56 MHz rf power, 100 KHz power, and etch time. Also, the particle count has a quadratic dependence as a function of process gas flow rate. Surprisingly, in the pressure range explored, particle deposition on the wafers is found to be independent of pressure. Auger and EDX chemical analysis of the particles reveals the presence of silicon, fluorine, oxygen, sulfur, and aluminum.

ISSN:1071-1023    

DOI:10.1116/1.586351

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The deposition rate of silicon dioxide from tetraethylorthosilicate/O2capacitively coupled plasmas increases with increasing applied rf power, increasing total pressure and decreasing wafer temperature. These measured deposition rate dependences can be explained by a simple plasma deposition model in which deposition occurs through both an ion‐assisted and an oxygen atom initiated pathway. The relative contributions of these pathways were roughly isolated using limiting step coverage measurements on low aspect ratio trenches. Limiting step coverages decreased, and hence directionality increased, with increasing rf power density, decreasing total pressure, and increasing wafer temperature. A simple bulk plasma chemistry model combined with an analytical sheath model was developed to qualitatively explain our experimental findings. The model suggests that the ion‐enhanced deposition rate is directly proportional to oxygen ion flux, with a reactive sticking coefficient approaching unity. Using literature values for reaction rate parameters and rate forms for oxygen plasma reactions, the rate of the neutral‐induced deposition reaction was found to be nearly independent of temperature and tetraethylorthosilicate concentration and directly proportional to oxygen atom concentration. The model reveals that the influence of an activated atomic oxygen surface recombination reaction on oxygen atom concentration is responsible for the apparent negative activation energy for deposition of −2 kcal/mol. The model further shows that under the conditions of the experiments, oxygen atom loss was controlled by surface reaction processes and convective flow; volume recombination reactions were found to be relatively unimportant.

ISSN:1071-1023    

DOI:10.1116/1.586361

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The change in sheet conductance of a thin, highly doped layer of GaAs is measured after exposure to inert gas plasmas (He, Ar, and Xe) and to molecular gas plasmas (CCl2F2, CF4, SF6, and O2) in a parallel‐plate rf discharge. In order to compare these data, the change in sheet conductance is converted to a damage depth scale. A different linear relationship is found for the damage dependence on the rf‐induced dc bias for each plasma. An inverse‐mass relationship is derived from the data for He, Ar, and Xe plasma exposures. Using this, two models are tested for their ability to predict the damage from the molecular gas plasmas. For one model, the assumption is that damage is caused by molecular ions that remain intact upon impact. For the other model, which is quite successful at predicting the measured damage, the assumption is that molecular ions fragment completely upon impact. This interpretation indicates that Cl+and/or F from CF+in CCl2F2plasma, F from CF+in CF4plasma, and S from SF+in SF6plasma are responsible for the measured damage effect. Neither model adequately predicts the low level of damage from O2plasma. Helium ions caused the greatest amount of damage; when mixed with CCl2F2, the measured damage was a factor of three lower. Using optical emission spectroscopy, quenching of He ions was observed when molecular gases were introduced into a He plasma. Quenching was also observed in other mixed gas plasmas and this indicates that ions with ionization potentials substantially higher than those of other ions in the plasma will not be formed in typical rf glow discharges.

ISSN:1071-1023    

DOI:10.1116/1.586377

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Polysilicon emitter bipolarnpntransistors, silicided with platinum, exhibited emitter‐base leakage after the final passivation thermal cycle. Transmission electron microscopy studies revealed platinum silicide (PtSi) spiking through the polysilicon into the emitter‐base region, indicating an apparent release of Pt during high temperature (>400 °C) processing. A technique was developed to study the phenomenon using unpatterned monitor wafers. Observations from a series of tests indicate arsenic dose, Pt thickness, Pt sinter temperature, PtSi capping material, postsilicide formation temperatures, and exposure to oxygen during high temperature treatments (after silicide formation) as the major factors influencing PtSi spiking.

ISSN:1071-1023    

DOI:10.1116/1.586388

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A negative‐differential‐resistance (NDR) device with a sawtooth‐doping‐superlattice (SDS) structure, prepared by molecular‐beam epitaxy, has been fabricated and demonstrated. The SDS structure contains two different δ‐doping superlattices. Multiple‐state NDR performance is observed due to the strong field effect and avalanche multiplication. Theoretical analysis for a single δ‐doping structure and a SDS structure is carried out to study the two‐dimensional electronic properties of quantized states and minibands. An S‐shaped NDR device with the SDS structure is fabricated and studied. The δ‐doping density profile provides a barrier height variation in the superlattice which influences the transport properties. With adequate design of device parameters, e.g., superlattice periods and doping density, the proposed structure may provide good potential for multiple‐state logic circuit applications.

ISSN:1071-1023    

DOI:10.1116/1.586391

出版商:American Vacuum Society    

年代:1992

数据来源: AIP