摘要:

In this article, by using surfaceI–VandC–Vcharacteristics, the levels of moisture uptake and the degree of surface polarization were studied on the newly developed all-aromatic and aromatic/aliphatic copolyester thermosetting thin films with a thickness of 1.0–5.0 μm. The all-aromatic copolyester films which contain more rigid structures appear less polarizable and less hygroscopic compared to aromatic/aliphatic copolyester. It was also found that both the surface current leakage and the polarization are lower than those of the commercially available polyimide systems. The data suggested three types of moisture which could be described by the dehydration conditions required to restore originalC–Vcharacteristics. The effects of curing conditions on moisture absorption and polarization are also presented.

ISSN:1071-1023    

DOI:10.1116/1.589766

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

In many chemical engineering processes the input control parameters and the product output quality are monitored dynamically in real-time. Almost all the processing steps associated with semiconductor manufacturing are chemical processes in which the surface of crystals or thin films are being chemically modified.In situmonitoring of the wafer attributes in real-time is essentially nonexistent in modern semiconductor manufacturing. For plasma etching processes several new diagnostic techniques (e.g., full-wafer imaging interferometry and ellipsometry) provide improved endpoint observation and some provide metrics for the state of the wafer at a given time. However, the methods that do provide metrics are usually quite expensive for a manufacturing environment. We propose a method whereby simple and economic endpoint methods can indicate in real-time the state of the wafer. Our method consists of finding the algorithm to mapin situwafer-state signatures (e.g., interferometry, ellipsometry) to wafer attributes and then mapping the process signatures (e.g., reflected rf power, pressure, flow rate, OES) to wafer-state signatures. From these we then have an abstract mapping from the process signatures to the wafer attributes in real-time. In this article we suggest that a learning machine can perform the mapping between process signatures, as a function of time and wafer state signatures, as a function of time.

ISSN:1071-1023    

DOI:10.1116/1.589767

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The effect of thermal annealing on the composition and morphology of the surface of strained SiGe layers grown on Si is investigated in the temperature range 400–900 °C. We show that Ge segregation starts at 400 °C and increases with increasing temperature. Above 700 °C, strain relaxation leads to the formation of islands on the surface. By combining atomic force microscopy and Auger electron spectroscopy we demonstrate that these islands are Ge rich and that at 900 °C rather pure Ge islands are formed on a Si rich underlying layer.

ISSN:1071-1023    

DOI:10.1116/1.589768

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The conductivity and Hall coefficient of polycrystalline SiC films deposited on quartz are studied in the temperature ranges of 13–1275 K and 17–800 K, respectively. Since conductivities were monotonically increasing with the increasing temperature, these films can be used as thermistors over the entire temperature range. While Hall mobility shows a weak temperature dependence, the electron concentration, as computed fromn=1/qRH,increases exponentially with temperature from1019to4×1020 cm−3.Three well-separated activation energies, computed from the measured conductivity and Hall concentration, are in the ranges of 0.4–3.8 meV, 7–20 meV, and55.5±5 meV.Due to high electron concentration measured at temperatures as low as 17 K, impurity/defect related conduction or thermally activated hopping may be dominant at low temperatures.

ISSN:1071-1023    

DOI:10.1116/1.589769

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have used x-ray photoelectron spectroscopy to determine the chemical elements present on the tops, sidewalls, and bottoms of submicron metal features etched in a high density inductively coupled plasma source usingCl2/BCl3gas mixtures. X-ray photoelectron spectroscopy analyses have shown that aluminum oxide is deposited on all the surfaces of the features exposed to the plasma due to erosion of the alumina liner located in the source region. A chlorine rich carbon film is formed on the sidewalls and at the bottom of the aluminum features during the etching process. At the bottom of the features, chlorine species must diffuse through the carbon layer to etch aluminum whereas spontaneous reactions between chlorine and aluminum are blocked on the sides of the features. On the sidewalls of the features, aluminum oxide species coming from the sputtering of the alumina liner are embedded in the carbon rich film as it grows. This sidewall passivation film enhances anisotropic etching by providing a thin protective layer against spontaneous etching reaction of chlorine with aluminum.

ISSN:1071-1023    

DOI:10.1116/1.589770

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The pressure dependence of the etch rate in an Al etching reactor has been studied with the goal of developing a method of numerically simulating the etching process. Experimentally, the etch rate was measured at pressures between 3 and 100 mTorr and reached a maximum at about 10 mTorr, whereas the calculated etch rate, which took the etching reaction between Al andCl2on an Al surface into account, increased with pressure. To explain the experimental data, the residence timeτ0of the inhibitor adsorbed on the Al surface and time-averaged surface coverage were included in the calculations. In the low-pressure region below 10 mTorr, the etch rate increased with an increase in pressure, due to the increasedCl2flux on the Al surface. On the other hand, in the high-pressure region over 10 mTorr, the etch rate decreased when the effect of the inhibitor became stronger; this was explained by developing an improved model. Consideration of the inhibitor adsorbed on the Al surface is important, where the increase ofτ0with pressure is necessary to precisely simulate the correlation between the etch rate and pressure.

ISSN:1071-1023    

DOI:10.1116/1.589772

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The kinetics of surface processes occurring onTiSi2andCoSi2thin films in the afterglow of aNF3plasma are studied. Analysis of the silicide surfaces by x-ray photoelectron spectroscopy and ellipsometry shows that a metal fluoride film forms duringNF3treatment. The thickness of the metal fluoride film on top ofCoSi2at 280–373 K andTiSi2atT300 K,the influence of theTiF4desorption becomes important. Both Co and Ti fluorides are completely removed in aH2SO4/H2O2mixture. After this treatment the silicide surface contains only 3–4 nm of silicon dioxide. Based on insight obtained in the fluorination process, the equations describing both the kinetics ofCoSi2andTiSi2etching and the change of selectivity ofSiO2etching towards the silicides are explained.

ISSN:1071-1023    

DOI:10.1116/1.589773

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Fluorinated gas discharges are widely used by the semiconductor industry in etching and chamber cleaning applications, but the performance of these discharges varies in unpredictable ways, for unknown reasons believed to be electrical in origin. To investigate possible mechanisms for this behavior, we have measured the electrical characteristics ofNF3/Ar,CF4/O2/Ar,andC2F6/O2/Archamber cleaning plasmas at 6.7–267 Pa in a 13.56 MHz, capacitively coupled, parallel-plate reactor, using radio-frequency current and voltage probes and optical emission spectroscopy. From the measurements, power losses in the external circuitry surrounding the discharge were determined. Furthermore, using the measurements and equivalent circuit models, the mechanisms by which power was absorbed within the discharge itself were investigated. Power was absorbed most efficiently at particular values of the discharge impedance. These optimal impedances occur in the middle of a transition from capacitive impedances at low pressures to resistive impedances at high pressures. These results illustrate that the plasma impedance is a useful parameter for monitoring and optimizing plasma processes in highly electronegative gases.

ISSN:1071-1023    

DOI:10.1116/1.589774

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

GaAs was nitrided in the helicon-wave exitedN2+Armixed plasma without and with a short-time pretreatment in inductively coupledO2+Armixed plasma. Nitridation of GaAs was also attempted using the inductively coupledN2+O2mixed plasma. Relatively good capacitance–voltage(C–V)characteristics were obtained as compared with those reported in a previous article, especially for the GaAs samples treated inN2+Arplasma with the pretreatment inO2+Arplasma and treated in theN2+O2plasma. Positive bias-temperature stress improved, to a certain degree, theC–Vcharacteristics. Photoluminescence at low temperature showed that the interface with good electrical quality was obtained after theseN2-plasma treatments. X-ray photoelectron spectroscopic data indicated that the stable GaN bonds were formed through nearly the whole depth of the grown film, with very small amounts of the suboxides of Ga and As. This indicates thatN2-plasma treatment substantially suppressed oxidation of GaAs.

ISSN:1071-1023    

DOI:10.1116/1.589775

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The thermal nitridation of GaAs(100) with ammonia was investigated by synchrotron radiation photoemission spectroscopy and atomic force microscope. This study revealed the chemical composition, chemical states, and morphological changes in the nitridated surface layer. We observed that ammonia can be decomposed to an activated nitrogen atom above 700 °C forming GaN on the surface. Thermally nitridated layers were composed of metallic Ga and GaN islands that are elongated along the [011] direction to relax the tensile strain in the [01̄1]direction. As the nitridation temperature increased, the composition of GaN increased in the nitridated layer due to the efficient thermal decomposition ofNH3and the subsequent incorporation of the N atom into the metallic Ga. The surface morphology of the nitridated layer, on the other hand, became substantially roughened at higher temperatures.

ISSN:1071-1023    

DOI:10.1116/1.589776

出版商:American Vacuum Society    

年代:1998

数据来源: AIP