摘要:

Microcrystalline silicon(μc-Si)was deposited in a simple, low cost microwave electron cyclotron resonance plasma system byH2dilution of 2%SiH4/Ar.The film growth and properties have been examined with substrate temperatures between 300 and 450 °C for pressures of 1–40 mTorr. Raman spectroscopy has been used extensively to study the microstructure of the film, and to determine the crystallized fraction and grain sizes in the film, for growth variations caused byH2dilution, growth pressure, and temperature.H2dilution of the plasma is found to increase the grain size and the crystallized fraction of the deposited films. Crystallization could also be initiated in the films deposited using only the Ar dilutedSiH4by increasing the power coupled to the discharge. Increasing theH2dilution results in compact films with a low hydrogen content, while a decrease is seen to create more voids in the film. Theμc-Sifilms (∼70% crystallized fraction), prepared at 400 °C, with grain sizes between 200 and 300 Å, exhibit a low dark conductivity of3×10−6S/cm with conduction activation energies between 0.3 and 0.43 eV. The structural properties of the film, evaluated by Raman spectroscopy and evolved gas analysis, are correlated with the dark/photoconductivity observed in the film. The experimental data suggest etching by atomic hydrogen to be the primary mechanism responsible for the crystallization of the films.

ISSN:0734-2101    

DOI:10.1116/1.581481

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Silicon oxynitride films exhibiting refractive indexes in the 2.01–1.49 range have been deposited in a plasma assisted chemical vapor deposition system usingSiH4+NH3+O2gas mixtures. TheO2/NH3gas ratio was varied in order to obtain different oxynitride compositions, ranging from silicon nitride to nearly stoichiometric silicon oxide. A single peak, in contrast to two separate peaks normally associated with silicon oxide and silicon nitride, was observed in the IR spectra, indicating the formation of a unique oxynitride compound. The IR absorption spectra as well as the refractive indexes measured by ellipsometry were used to estimate the stoichiometry of the films, the results being well correlated to Auger analysis.

ISSN:0734-2101    

DOI:10.1116/1.581513

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Hydrofluorinated amorphous silicon–carbon alloys(a-Si1−xCx:H,F)are obtained by plasma decomposition ofSiF4–CH4–H2mixtures. The analysis of the plasma phase, by mass spectrometry and optical emission spectroscopy, and of the resultant material, by Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, allows us to gain information about the film growth chemistry. The growth kinetics and the material composition of thea-Si1−xCx:H,Ffilms are studied as a function of the addedCH4amount to theSiF4.The peculiarity ofSiF4–CH4system is that smallCH4addition (10%) toSiF4produces silicon carbon alloys with high C incorporation (60 at. %). This has been explained on the basis of a growth model in which the chemisorption ofCHnon the surface prevails on that ofSiFn.

ISSN:0734-2101    

DOI:10.1116/1.581418

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Pure and conductingRuO2thin films were deposited on a Si substrate at 250–450 °C usingRu(C11H19O2)3as a precursor by low pressure metal organic chemical vapor deposition (MOCVD). At a lower deposition temperature, the smoother and denserRuO2thin films were deposited. The amount ofO2addition did not seriously affect the properties of theRuO2thin film. TheRuO2thin films which were crack free and well adhered onto the substrates showed very low resistivity of 45–60 μΩ cm. At a lower deposition temperature and a smaller amount ofO2addition,RuO2thin films showed better step coverage, indicating that MOCVDRuO2thin films fromRu(C11H19O2)3can be applied for an electrode of high dielectric thin films for a capacitor of ultralarge scale integrated dynamic random access memory.

ISSN:0734-2101    

DOI:10.1116/1.581419

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The inductively coupled plasma etching of platinum withAr/Cl2gas chemistries is described. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical binding states of the etched surface with variousAr/(Ar+Cl2)mixing ratios. Atomic percentage of Cl element increases with increasingAr/(Ar+Cl2)mixing ratio with the exception ofAr/(Ar+Cl2)mixing ratio of 1. At the same time, the peaks that seem to be subchlorinated Pt at XPS narrow scan spectra are found and Cl–Pt bonds rapidly increase atAr/(Ar+Cl2)mixing ratio of 0.62. Quadrupole mass spectrometry (QMS) is used to examine the variations of plasma characteristics with variousAr/Cl2gas chemistries. QMS results show thatCl2molecules are converted to Cl radicals with adding Ar gas toCl2plasma. QMS results support the increased atomic percentages of Cl elements on the etched Pt surface. Single Langmuir probe measures ion current density with variousAr/Cl2gas plasma. Ion current densities are used to investigate the ion bombardment effects on the etched surface. Thin film thickness measuring system, scanning electron microscope and a four-point probe are used to extract the Pt etching characteristics. The maximum etch rate of Pt is approximately 140 nm/min at theAr/(Ar+Cl2)mixing ratio of 0.9. These results are consistent with XPS, QMS, and Langmuir probe data.

ISSN:0734-2101    

DOI:10.1116/1.581420

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

An experimental and theoretical investigation of a Helicon plasma source has been completed as a precursor to the development of an automatic system for controlling the operation of such sources. The number density in an argon plasma has been observed over a parameter space defined by the input variables of filling pressure (1–100 μbar), magnetic field (0–450 G) and rf power (0–1250 W). Four distinct modes of operation have been identified, namely: electrostatic, inductive, Helicon and high pressure Helicon modes. A global model of the source has been modified to include the effect of radial confinement by the axial field. Comparisons with the experimental results show that the model generally can predict the plasma density to within 15%–20% for both the inductive and Helicon modes. It is found that the ratio of the ion cyclotron radius compared with the radius of the plasma is a useful measure of the amount of confinement. An alternative measure based on the product of the ion cyclotron frequency and the collision time for momentum transfer does not lead to satisfactory agreement between the global model and the experimental observations. The modified global model appears to describe the behavior of the plasma well enough to allow the development of a conventional control system that can be used within each of the modes. The model, however, is unable to predict the locations of the mode jumps within the parameter space.

ISSN:0734-2101    

DOI:10.1116/1.581421

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A new technique for semiconductor epitaxy at low substrate temperatures is presented, called low-energy dc plasma enhanced chemical vapor deposition. The method has been applied to Si homoepitaxy at substrate temperatures between 400 and 600 °C and growth rates between 0.1 and 1 nm/s, using silane as the reactive gas. The quality of the Si films has been examined by reflection high-energy electron diffraction, scanning tunneling microscopy, cross-section transmission electron microscopy, and high-resolution x-ray diffraction. Two effects have been identified to lead to the formation of stacking faults after an initial layer of defect-free growth: (1) substrate bombardment by ions with energies in excess of 15 eV, and (2) hydrogen adsorption limiting the surface mobility of Si atoms and silane radicals. Both result in the accumulation of surface roughness, facilitating the nucleation of stacking faults when the roughness reaches a critical level. Defect introduction can be eliminated effectively by biasing the substrate during growth and by decreasing the hydrogen coverage, either by admixing small amounts of germane to the silane or by using a sufficiently high plasma density.

ISSN:0734-2101    

DOI:10.1116/1.581422

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

GaN thin films were deposited by reactive molecular beam epitaxy method with a modifiedASTeX® compact electron cyclotron resonance (ECR) plasma source of nitrogen. The effect of different ECR exit apertures on the growth rate and photoluminescence properties of GaN films was investigated. An aperture with a matrix of 1.6 mm holes allowed for GaN films with good optical properties at growth rates up to 1μm/h.Apertures of larger diameter resulted in semi-insulating films. Room temperature photoluminescence for both undoped and Si-doped GaN films with full width at half maximum less than 100 meV has been obtained at the highest growth rates. We suggest that such an aperture effectively blocks the energetic ions from reaching the substrate thus reducing ion damage, resputtering, and increasing the Ga surface population. It also creates a higher pressure inside the ECR resonator, and therefore, provides a higher flux of active species. While further optimization will result in better GaN film quality, our results suggest that the growth rate in Ga-rich condition is limited by the microwave power available in the ASTeX compact ECR source.

ISSN:0734-2101    

DOI:10.1116/1.581423

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The plasma enhanced chemical vapor deposition of silicon nitride films fromSiH4andN2gases was investigated below 450 K in a helical resonator plasma reactor usingin situspectroscopic ellipsometry andin situattenuated total reflection Fourier transform infrared spectroscopy. Silicon nitride growth proceeds through nitridation of a thin Si-rich region at the film surface and the effects of the externally controlled parameters, such as plasma power and pressure, on the film composition and structure can be understood in terms of this mechanism. The key factor that affects the film composition and structure is the active nitrogen(N2*)flux arriving at the surface which determines the nitridation rate of Si–Si bonds. Silicon nitride films deposited using low plasma power and high pressure, conditions that produce lowN2*flux, contains a relatively high concentration of H in the form of Si–H anda-Si inclusions. Increasing the power or decreasing the pressure results in higherN2*flux and nitridation rate. The films deposited under such conditions have less SiH anda-Si incorporation but higherNHx(x=1,2) which disrupts the interconnectedness of the nitride network resulting in films that contain voids. Film properties can be tailored and optimized between these two extremes by manipulating power and pressure.

ISSN:0734-2101    

DOI:10.1116/1.581424

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Aluminum nitride films have been deposited on Si(111) substrates at different substrate temperatures using two techniques; pulsed laser deposition or reactive magnetron sputtering. The films deposited by either of the techniques have been characterized by x-ray diffraction and transmission electron microscopy to determine the crystalline quality, grain size, and epitaxial growth relation with respect to the substrate. The bonding characteristics and the residual stresses present in the films have been evaluated using Raman and Fourier transform infrared spectroscopy. Secondary ion mass spectrometry has been performed to determine the nitrogen stoichiometry and the presence of impurities such as oxygen and silicon. The adhesion strength of the AlN films to the silicon substrate and the wear resistance have been determined by scratch test and a specially designed microscopic wear test. A comparison of the different characteristic features associated with the AlN films deposited by pulsed laser deposition or magnetron sputtering is presented with particular emphasis to electronic and tribological applications.

ISSN:0734-2101    

DOI:10.1116/1.581425

出版商:American Vacuum Society    

年代:1998

数据来源: AIP