摘要:

The discharge characteristics of an unbalanced magnetron sputtering device, equipped with a 100‐mm‐diam planar circular target and with two electromagnetic coils, have been analyzed in a range of operation pressures from 0.02 to 1 Pa. The variation of discharge extinction and ignition pressures and target voltage is presented as a function of the ratio of currents in the magnetron coils and discharge current. A maximum discharge current beyond which it is not possible to sustain the discharge at low pressures has been observed. This extinction current increases with operating pressures. An explanation for the effect is based on the loss of gas from the plasma due to gas heating with energetic sputtered particles and subsequent gas density rarefaction in the near target region. Higher pressure is thus necessary to keep constant gas density in the magnetron plasma when the discharge current is increased. The magnetic field configuration is presented for several values of the ratio of currents in the magnetron coils and correlated to the variation of discharge extinction and ignition pressures, extinction current, and target voltage. The low pressure operation of the magnetron strongly depends on optimization of the magnetic field shape on the sputtered target. The deposition rate of titanium films is a linear function of magnetron power up to 2.5 kW and does not depend on Ar pressure in the pressure range studied (0.08–0.6 Pa). ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146181

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A novel experimental method has been developed and applied to measure the thermal conductivity of a thin (5.6 &mgr;m thick) boron‐doped diamond film produced by a hot filament CVD process. Thermal fields were created by Joule heating in a 3‐mm‐diam, free‐standing diamond diaphragm; infrared imaging thermography was used to quantify these fields. Parameter estimation was applied to determine the thermal conductivity of the film using more than 100 temperatures in each property determination. The experimental design chosen was selected on the basis of an analysis which maximized the sensitivity for the determination of thermal conductivity while minimizing the uncertainty in the estimation of this property. Parameters such as characteristic length, film resistivity, and thickness were chosen from the model to reduce convective effects, obtain the desired temperature rise, and minimize the uncertainty in the estimation of the thermal conductivity. Preliminary results for the thermal conductivity were obtained using the method of least squares to minimize the error between the measured temperatures recorded by the infrared temperature acquisition system and the calculated temperatures determined by the optimal radial heat flow model. A single doped film was energized at three power levels in five experiments. The thermal conductivity was determined to be 240±11 W/m K. The measured standard deviation of the mean matched the estimated uncertainty closely and the relative contributions to the experimental uncertainty have been quantified. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146182

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A two‐dimensional (2D) imaging ellipsometric microscope (IEM) has been constructed. It overcomes several problems inherent in existing 2D imaging ellipsometers. One can use IEM to measure and map the 2D film thickness profile with high spatial resolution and thickness sensitivity. The performance of the device is demonstrated through the study of the thin‐film profile of a spreading liquid drop on a molecularly smooth silicon wafer surface. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146183

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Diffuse reflectance spectroscopy can be used as a noninvasive probe for measurement of temperature in real time. We have measured the precision of this technique to determine the temperature of Si and GaAs substrates during semiconductor processing. Our results show that the standard deviation of the noninvasive optical technique is less than 1.5 °C for GaAs and less than 2.0 °C for Si over the temperature range 25 °C<T<600 °C. This standard deviation compares favorably to that for a type‐Kthermocouple used in the same measurements: s.d.<1.5 °C. These results support the notion that noninvasive optical temperature measurement can be used in semiconductor processing with a precision approaching that of a thermocouple. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146184

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the design of an ultrahigh vacuum compatible vapor dosing system for organometallic compounds. A unique feature of this doser is the elimination of all metallic surfaces in order to reduce the reactivity of the organometallic molecules towards the doser walls. The vapors only come in contact with glass, Teflon, and Kalrez and the doser is heatable to temperatures of 150 °C. A novel modification to a commercial glass stopcock is described. These modified valves are used in the doser to seal the ultrahigh vacuum system from the organometallic sample compartment and have been shown to be able to allow the vacuum system to maintain ultrahigh vacuum conditions even when the sample compartment is vented to atmosphere. Spring‐loaded Teflon seals are used to seal the valve shaft against the glass wall thereby maintaining ultrahigh vacuum conditions and a chemically inert surface for the organometallic compounds. A further modification to these commercial valves is described allowing it to function as the sample compartment for the organometallic material. This compartment features a heatable reservoir, vacuum seals to ultrahigh vacuum levels, and a rapid exchange design to permit the interchange of dosing materials. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146119

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The characterization of semiconductor heterostructures requires different measurement techniques such as photoluminescence, Shubnikov–de Haas, and cyclotron resonance. We present a simple experimental setup which allows to make use of all these techniques without changing the equipment. There is no need for electrical contacts. The performance is demonstrated on InxGa1−xAs/InP quantum wells. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146120

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This paper presents a precise absolute measurement of the drift velocity and mobility of electrons in high resistivity silicon at room temperature. The electron velocity is obtained from the differential measurement of the drift time of an electron cloud in a silicon drift detector. The main features of the transport scheme of this class of detectors are: the high uniformity of the electron motion, the transport of the signal electrons entirely contained in the high‐purity bulk, the low noise timing due to the very small anode capacitance (typical value 100 fF), and the possibility to measure different drift distances, up to the wafer diameter, in the same semiconductor sample. These features make the silicon drift detector an optimal device for high precision measurements of carrier drift properties. The electron drift velocity and mobility in a 10 k&OHgr; cm NTDn‐type silicon wafer have been measured as a function of the electric field in the range of possible operation of a typical drift detector (167–633 V/cm). The electron ohmic mobility is found to be 1394 cm2/V s. The measurement precision is better than 1%. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146121

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

With semiconductor compounds of the group III–V and in particular GaAs, energy band structure investigations have been carried out by several researchers by effecting, in particular, Hall effect measurements under hydrostatic pressure. Their results allow one to conclude that the energy gap increase which occurs with increasing pressure up to a transition point of up to approximately 33 kbar, leads the semiconductor Hall sensitivity to increase correspondingly with applied pressure. Thus, commercialn‐type GaAs Hall elements can effectively be used as pressure sensors, and subsequently, if appropriate calibration of the output Hall voltage to corresponding values of pressure is carried out, as pressure transducers. ©1995 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1146122

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A thermal‐wave resonant cavity was constructed using a thin aluminum foil wall as the intensity‐modulated‐laser‐beam induced oscillator source opposite a pyroelectric polyvilidene fluoride wall acting as a signal transducer and cavity standing‐wave‐equivalent generator. It was shown that scanning the frequency of oscillation produces the fundamental and higher overtone resonant extrema albeit with increasingly attenuated amplitude—a characteristic of thermal‐wave behavior. Experimentally, scanning the cavity length produced a sharp lock‐in in‐phase resonance with simple linewidth dependencies on oscillation (chopping) frequency and intracavity gas thermal diffusivity. The thermal diffusivity of air at 294 K was measured with three significant figure accuracy: 0.211±0.004 cm2/s. The novel resonator can be used as a high‐resolution thermophysical property sensor of gaseous ambients. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146123

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This article describes a new two‐color pyrometer able to obtain multiple temperature reading using charge couple device type sensors. The device was tailored to fit the characteristics of self‐propagating high‐temperature synthesis processes in order to be able to detect temperature profiles and propagation rates of the combustion front. The light intensities at the two working wavelengths and the relative temperature profile are detected in 512 or 1024 points on the sample surface. The time between the acquisition of two profiles can be varied between 100 ms and 10 s. The pyrometer is interfaced with the BUS of a PC and is fully software programmable. The constructive details, procedure for sensors alignment, and temperature calibration are described. Few examples of applications are discussed. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146124

出版商:AIP    

年代:1995

数据来源: AIP