The application of in-situ grazing incidence X-ray diffraction to the determination of the atomic structure of surfaces and to the quantitative evaluation of mifit strains in the very first stages of heteroepitaxy is illustrated by the particular example of the molecular beam epitaxial (MBE) growth of GaAs on Si. Such experiments have been made possible by the coupling of MBE chambers with ultra-high vacuum compatible X-ray diffractometers and the advent of powerful synchrotron radiation X-ray sources.

A new x-ray analytical technique, Total reflection X-Ray Fluorescence (TXRF) analysis, is now available for process development and control of heavy metal surface impurities in microelectronic integrated processing. The detection limits are on the order of 1011 atoms/cm2, several orders of magnitude better than Auger electron spectroscopy and electron spectroscopy for chemical analysis. The measurements are also quantitative in the top 3-4 nm of the surface, unlike secondary ion mass spectrometry. TXRF data are presented to support the quantification method, to show the stability of the measurement procedure, and to demonstrate application to process development of dry etching, ion implantation, and rapid thermal annealing, and process control of substrate cleaning. In addition, the TXRF signal change with incident angle is used to distinguish plated contamination from residue or particulate contamination.

Use of sapphire substrates instead of silicon for measurement of phosphorus in BPSGs and PSGs can improve the precision of the phosphorus measurement from 3σ = 0.32 wt.% to 3o = 0.05 wt.%. Improvement in precision results from elimination of the background silicon counts, elimination of film thickness as a factor in phosphorus calculations, use of peak intensity ratios rather than absolute intensities, and elimination of wafer reloading effects.

We have successfully applied the contactless, non-invasive electromodulation method of photoreflectance as an in-situ sensor of the OMVPE process. The direct gaps of GaAs and Ga_1-xAl_xAs(x = 0.17) have been measured as a function of temperature up to 690°C, in-situ, under actual OMVPE growth conditions, including a rotating substrate holder (~ 500 rev/min) and flowing gases.

In this study, GaAs surface damage resulting from reactive ion etching (RI E) and wet etching was assessed by temperature dependent photoluminescence (PL) and room temperature Raman spectroscopy. Four samples of GaAs grown by molecular beam epitaxy (MBE), etched and then epitaxially regrown were analyzed. Two of these samples were etched reactively, one with HC1 and the other with C12. The third sample was wet etched and the final sample was used as a control. AlI the samples were initially cleaved from the same MBE grown wafer and were regrown together in order to maintain similar growth conditions. To further elucidate the damage, cross-sectional Transmission Electron Microscopy (TEM) was performed on these samples. For all of the samples except the HC1 etched, it was possible to obtain a fit to the temperature dependence of the PL intensity of the exciton. In addition, we found a strong correlation between the samples' relative LO phonon Raman intensity to the relative PL intensities in which the sample etched by HC1 was found to be inferior to the other samples. Further, because of the presence of the "forbidden" TO peak, the Raman spectra indicated the presence of structural defects such as dislocations and twinning. Cross-sectional TEM was used to compare the interface region of the four samples where the damage due to etching and the quality of initial regrowth is observable. The TEM results confirmed the presence of dislocations and twinning defects in varying concentrations correlating to the optical observations of the samples.

Damage threshold energies for a pulsed XeCl excimer laser at 308nm have been obtained for a number of microelectronic materials which may have patterning applications. A photoacoustic technique is used to identify the damage process. An example of laser patterning illustrating the constraints on laser energy is given.

Proper instrumentation, documentation, and analysis are crucial to the continued advance of micro-electronic materials science. Many important phenomenon are visible. Many of those are progressive events that need observation throughout their transitory period. Microelectronics scientists and engineers have long required optical systems tools which properly handle visible phenomena. An optical based system, called a high-resolution Still/Video system, to fulfill crucial microelec-tronic needs is available. Microelectronic dimensions require the highest possible resolution to resolve the small details. The system provides 1134 by 486 pixel video frames. The transient nature of many events requires video and the associated capability of video recording. The system stores over 14,000 high-resolution video frames on a single standard commercial VHS tape. The widespread use of microscopy requires the ability to operate with a variety of optical microscopes. The system is directly compatible with most microscopes. In addition, analysis requires the ability to produce film and computer processed results of all crucial images. The system has both a companion film printer and a direct computer interface.

The deposition of high quality superconducting thin films based on the metal oxides has given rise to a variety of needs for diagnostic techniques. These needs are primarily for monitoring, 1. the material ejection process from the target, 2. the ejected vapor interaction with the background oxygen, 3. the crystallization dynamics at the substrate and 4. post deposition analysis and processing of the film. This paper summarizes some of the recent work in this direction

In 1986, Bendorz and Muller1 discovered that metallic oxide with a perovskite structure in the La-Ba-Cu-O system exhibited superconductivity at 20°K. In early 1987, Chu and his co-workers² made a YBa2Cu3O7-x compound which had a Tc higher than the temperature of liquid nitrogen. Since these discoveries, the research and development of high-Tc superconductors has aroused unpecedented attention, not only from the scientific community, but also from various industries and governments. As these new superconducting materials are in general very "brittle" and difficult to machine, it is extremely difficult to fabricate them into thin wires. In addition, practical use of new high-Tc superconductors will require materials with very high critical current density. Thus thin film preparation is particularly important for many applications of superconductors, such as electronics for the computer industry. Films with high superconducting transition temperatures have been prepared by electron beam evaporation, organometallic chemical vapor deposition, DC sputtering, molecular beam epitaxy, and laser evaporation and deposition processes. For example, Rice et al.3 used electron beam and thermal evaporation to produce Ca-Sr-Bi-Cu-O superconducting films from CaF2, SrF2, Bi, and Cu targets. Berry et al.' produced a superconductive film by organometallic chemical vapor deposition. Hellman et al.⁵ used molecular beam epitaxy to produce a DyBa2Cu307, film on a SrTiO3 substrate. Lynds et al.6 used a Nd-YAG laser beam to do laser evaporation and deposition to prepare a YBa2Cu307-x thin film from targets of Y203, Bat CO3, and CuO. Kwok et al.⁷ applied a homogeneous excimer laser to obtain a film with the right stoichiometry of YBa2Cu307,. However, most of the films in the works cited above need to be annealed in an oxygen environment in order to produce superconductivity. Recently, several research groups obtained superconductive films of YBa2Cu307, by raising the temperature of the substrate and introducing oxygen into the chamber during the thin film preparation process.8 However, no superconductive films of the Bi-Sr-Ca-Cu-O or Tl-Sr-Ba-Cu-0 systems were obtained without oxygen annealing. Nevertheless, the right ratio of various metal elements is one of the key factors in achieving superconductivity. Superconductive films are usually obtained based on repeated trials and adjustments. Venkatesan et al.⁹ observed two distinct components during pulsed laser deposition of high-T, superconductive film. It was pointed out that the quality of the superconductive film depends on controlling the film stoichiometry. The role of introducing oxygen into the thin film preparation chamber has never been fully understood. Thus, the need for a real-time monitor for high-Tc thin film preparation is quite critical.

The Raman Microprobe MOLE provides the capability to acquire analytical quality Raman spectra with him spatial resolution. These spectra allow molecular and/or crystalline identification for contaminant analysis and microstructural studies. The ability of the Raman microprobe to identify organic contaminants is unique in the arsenal of analytical tools available in the manufacture of integrated circuits. Structural studies of materials undergoing engineering development include semiconductor superlattices, superconductors, diamond and diamond-like carbon (DLC) films.

This paper summarizes results of our investigations of growth on (001) and (110) GaAs by atmospheric-pressure organometallic chemical vapor deposition (OMCVD). We follow evolutions of surface species to a sensitivity of 0.01 monolayer (ML) on a time scale of 0.1 s under alternating flows of trimethylgallium (TMG) and arsine (AsH3) as functions of partial pressure, sample temperature, and surface orienta-tion. The reaction of TMG with an AsH3-saturated (001) surface is rate-limited by com-petition between desorption and decomposition of TMG molecules chemisorbed to surface lattice sites via an excluded-volume mechanism, while the reaction of AsH3 with the TMG-saturated (001) surface is essentially instantaneous. In contrast, TMG reacts essentially instantaneously with the AsH3 -saturated (110) surface while the AsH3 reaction with the TMG-saturated (110) surface is the rate-limiting step. However, the latter rate is not intrinsic to the AsH3-surface reaction but appears to be determined by desorption of adsorbed species that block active sites.

Examples of applications of in situ spectroscopic polarization techniques (from UV to IR) to the study of the growth of semiconductor materials are presented. The high sensitivity of these in situ diagnostics is emphasized. In particular, the ability of kinetic ellipsometry in the UV range, to study interfaces involving reactive processes like plasma deposition, with submonolayer resolution, is described. In the UV-visible range, it is shown that reflectance-difference spectroscopy (RDS) allows the real-time characterization of crystalline III-V materials and heterojunctions. In the infrared, ellipsometry appears particularly well adapted for performing detailed analysis of the vibrational properties and the growth processes of amorphous thin films. Such sensitivity to film deposition mechanisms illustrates the capacity of real-time optical diagnostics for fundamental studies and in situ control process.

We have used the contactless electromodulation technique of photoreflectance (PR) to investigate the strain in the near surface region (-100 R) of Si in thermally prepared (~100Å) Si/Si02 interfaces. We have tracked the position of the E1 optical feature (Λ3 - Λl transitions) relative to its position in a reference Si wafer (not intentionally oxided). From the observed red-shifts we can deduce both the magnitude and sign (tensile) of the strain. These observations are consistent with the compressive stress in the SiO, at the Si/Si02 interface as evaluated previously using it transmission, ellipsometry and laser-beam deflection studies.

We have studied the mechanisms of the copper metallization on P-silicon wafers immersed in CuCN solutions, using photoelectrochemical measurements and optical/electron microscopy. In this process the electroplating is enhanced by the minority carries in illuminated areas of the silicon. cathode. The photo-selective deposition with high resolution have been obtained only on low doped P-silicon. The kinectics of the film growth is strongly dependent on the film thickness, and two mechanisms have been identified. Patterns of resolution of ~4 microns can be realized only with thickness bellow ~20 nm. Further investigation is needed for prevent the oxidation of the as-deposited film.

An ultrahigh vacuum system has been built which allows molecular beam epitaxial deposition of compound semiconductors and scanning tunneling microscopy (STM) imaging, as well as angle-resolved photoemission, X-ray photoemission and Auger electron spectroscopies, and low energy electron diffraction. Samples can be moved from station to station for individual operations. We demonstrate the utility of the system with examples of homoepitaxial GaAs(100) and GaAs(111) surfaces, and heteroepitaxial GaAs/Si(100). We also compare the STM results with complementary measurements from the literature. Finally, we comment on the utility of such systems.

An ultraclean and integrated processing laboratory for Si technology is described whose purpose is to explore (1) the fundamental chemistry and physics of thermal processes, (2) the potential of ultraclean growth conditions for obtaining good materials properties, and (3) the integration of related process sequences in-situ. In-situ analysis and monitoring plays a key role in all three. Defect formation is analyzed by surface analytical techniques, based mostly on electron spectroscopies, and consequences for film growth are discussed. An important distinction is made between molecular contamination on the level of sub-monolayer coverages (of order 1014cm^-2 ) and individual point defects caused by particles (of order 103cm^-2). Different analytical techniques and detection schemes are required to deal with such vastly different contamination densities.

Self-supporting bi-layer structures of Al/SiO2 thin-films has been investigated by a combination "in-situ" of Rapid Thermal Processing (RTP) and Transmission Electron Microscopy (TEM). We observed that the Al/Si02 mismatch results in high tensile stress that contribute to slower the kinectics of the Al nucleation. Practically there is no change of the Al morphology in the annealed samples even at temperatures up to 720 K. A metastable Al silicide was observed at temperatures around 370 K.

Electron beam induced chemical vapor deposition of W and Si has been studied in a transmission electron microscope. WF6 and SiH2C12 were used as gas sources. Si and W clusters were initially formed. The W clusters, about 3nm in size, were β-W crystal, while the Si clusters were amorphous. The larger W clusters deposited on carbon films, about 10nm in size, were δ-W crystal. Deposition rates can be directly calcula,ted, by using this techniques. For example, a 120-kV electron beam at 100A/cm2 current density will deposit W at 5nm/min at 5x10^-7Torr, and Si at 2nm/min at 5x10^-5Torr. A W rod, 15nm in diameter, has been deposited using a 3-nm-dim focused electron beam.

Currently, there is increased interest in the polyimide / copper interface. This arises from the use of polyimide as a dielectric media between copper interconnect layers in multichip modules. In this paper we report on studies of the processes/reactions occurring at the polyimide-copper interface using Auger depth profiling and FTIR spectroscopy. The samples were prepared by spin coating polyimide onto the deposited sputtered copper metal. Following this coating, the polyimide film was heat treated to promote imidization for curing. Examination of the interface showed considerable intermixing of copper ions in the polyimide layer, as revealed by Auger depth profiling and FTIR. This penetration prevents the polyimide films from complete curing during the heating process therefore limiting the long term reliability and causing failure of the interconnect. A possible failure mechanism involving copper carboxylate in polyimide film is proposed. Experimental results will be presented in details.

When forming waveguides in LiNbO3 by Ti or H diffusion, measuring the lateral and depth distribution of the diffusing species is important to accurately model waveguide formation. We have analyzed waveguides using secondary ion mass spectrometry (SIMS) image depth profiling to provide a three-dimensional analysis of Ti-diffused and proton-exchanged waveguides 2-20 micrometers wide. Cesium ion bombardment and negative secondary ion spectrometry were utilized to obtain the optimal detection limits and sputtering rates. The image depth profiling technique consists of sequentially recording digital ion images of a sample as it is sputtered. Computer processing of the imaged volume allows cross-sectional images and depth profiles of selected areas to be constructed. Measured Ti-diffusion depth profiles are a function of initial Ti film thickness, stripe width, and processing conditions. Cross-sectional images of both types of waveguides shows that lateral diffusion of Ti is greater than that of H for 6 micrometer waveguides.

Titanium diffusion in lithium niobate (LiNbO3) is the most prevalent fabrication method for form-ing optical waveguides in this substrate. Three dimensional profiles of the diffused Ti can be used to model diffusion constants of Ti in LiNb03 and to predict optical properties. We have studied Ti diffusion in LiNb03 by image depth profilling mode of secondary ion mass spectrometry (SIMS). The novel application of SIMS to this substrate has enabled us to construct lateral cross sections at various depths as well as depth profiles. We varied the Ti thickness, Ti strip width, diffusion time and diffusion temperature to determine the diffused profile laterally and vertically. The SIMS depth profiles show that within the temperature range studied, the diffused profile depends strongly on the temperature with a weaker dependence on Ti thickness and diffusion time. Ti lateral cross sections at various depths indicate a concentra-tion dependent lateral diffusion constant. We calculated Ti diffusion constants and activation energies in the vertical dimension based on the SIMS data. The results of our study using this technique are applicable to integrated optics technology

In the process of the molecular beam epitaxy (MBE) the electron diffraction is traditionally used for nondestructive crystal-structure monitoring. We have shown that similar results could be obtained by detection of the second harmonic of the laser light generated in a film (SHG-method). Laser-assisted methods are very attractive for diagnostics in high-vacuum systems. It is easy to input and to output radiation via small diameter windows. It is also easy to realize distant continuous local monitoring during the growth process.