Although classical materials characterization methods have existed for many years, modern microanalytical techniques had their start just over twenty years ago. In this paper, I will discuss some of the common techniques available today including AES, XPS, or ESCA, RBS, SIMS, and EDAX. A comparison of the key capabilities and limitations will be given including sensitivity, spatial resolution, quantitative analysis, nondestructive testing, chemical state determination, and analysis speed. It is clear that the reason each of these techniques still exists as commercial instrumentation is that each provides a unique set of capabilities, but also a unique set of limitations. To become viable in the materials analysis arena, a new technique must offer a significant extension of the capabilities already available but not at the cost of too severe a set of limitations. Examples would be the development of tools that offer both high sensitivity with accurate quantitative analysis, or good spatial resolution with high sensitivity, or minimal damage but good spatial resolution, etc. A number of papers in this volume will describe the details of these emerging technologies which provide advances in these areas; and I will attempt here to put a number of these new developments in perspective with regard to the more commonplace techniques available.

The scanning electron microscope is now a common instrument in materials characterization laboratories. The basic role of the SEM as a topographic imaging system has steadily been expanding to include a wide variety of SEM-based analytical techniques. These techniques cover the range of basic semiconductor materials characterization to live-time device characterization of operating LSI or VLSI devices. This paper will introduce many of the more commonly used techniques, describe the modifications or additions to a conventional SEM required to utilize the techniques, and give examples of the use of such techniques. First, the types of signals available from a sample being irradiated by an electron beam will be reviewed. Then, where applicable, the type of spectroscopy or microscopy which has evolved to utilize the various signal types will be described. This will be followed by specific examples of the use of such techniques to solve problems related to semiconductor technology. Techniques to be emphasized will include: x-ray fluorescence spectroscopy, electron beam induced current (EBIC), stroboscopic voltage analysis, cathodoluminescence and electron beam IC metrology. Current and future trends of some of these techniques, as related to the semiconductor industry, will be discussed.

The application of Raman spectroscopy to various semiconductor thin film, interface and surface problems will be presented. Specific focus will be on the vibrational excitations of the materials systems which are probed by the Raman measurements. Experimental configurations are described which are optimized for general thin film analysis, microprobe analysis, and in situ UHV surface/interface analysis. The vibrational properties can be used for phase and composition identification, crystal/amorphous structure, strain, impurity configurations, and superlattice properties. Specific examples will include thermal processing of CVD Si films, microprobe of laser annealed films, MOCVD AlxGa1−xAs films, silicide formation and identification, amorphous superlattices, and hydrogen impurities in crystalline Si.

We review the technique of x-ray double crystal diffractometry as applied to measurement of microscopic profiles of strain in semiconductor materials. The first step in this technique is the extraction of average strains and layer thicknesses directly from the x-ray rocking curves. Profiles of strains with depth are then found by iterative fitting of the experimental rocking curves with trial distributions, incorporated into a theoretical model for the diffraction. The kinematic approximation is accurate for thicknesses up to 1μm in most semiconductors. For greater thicknesses, the more precise dynamical model must be applied.

Photothermal spectroscopy employs the small rise in temperature associated with the absorption of electromagnetic radiation to probe optical and transport properties of materials. A review of the various photothermal detection schemes is given, and examples which illustrate the power of this technique are reviewed.

This paper briefly reviews previous results and developments, then presents new results, using a novel surface analytical technique that uses non-resonant multiphoton ionization (MPI) of neutral atoms and molecules sputtered by an ion beam, or desorbed by an electron beam or laser beam. In this method, which we call surface analysis by laser ionization (SALI), the non-resonant MPI, or “laser ionization,” is coupled with state-of-the-art time-of-flight mass spectrometry to provide extremely sensitive, general, and readily quantifiable surface analysis. Examples are presented for two applications relevant to the semiconductor industry and for the analysis of the near surface region of two specially pretreated stainless steels. A discussion also describes the favorable prospects for implementation of SALI with submicron dimension liquid metal ion beams for microanalysis, including situations with electron beam sensitive samples.

Ion beam channeling analysis has recently been applied to lattice strain measurements on strained-layer superlattices (SLS). In this review talk, we outline three different methods of strain measurement: axial dechanneling, angular scans, and planar resonance. We describe the principles and illustrate them with examples; we also give a detailed theoretical treatment of the planar resonance effect in SLS's.

The use of deep-level transient spectroscopy for electronic defect characterization in semiconductors is reviewed with emphasis on the underlying principles and concepts.

Recognition of the importance of the mechanical properties of thin deposited films has received increasing attention over the past decade. The film or near surface region must be treated as a material to understand its particular mechanical properties in terms of the unique microstructure present. A vapor condensed film often has an extremely small grain size and gives brittle behavior. It is not uncommon to form an impurity stabilized amorphous film during growth.

In this paper emphasis is placed on concepts and recent instrumentation for measurements of the stress during film deposition. This growth stress and its distribution results from the microstructure plus the mechanical constraints of the underlying material, and may be modified by the processing. Both elastic and plastic components are present and local deformation maps allow a reasonable level of modelling. Lacking in this approach are experimental material parameters for the film, near surface, or interfacial material. New data for the tensile properties of cast polystyrene and SiO films is presented.

We describe a highly sensitive, noncontact method for inspecting important, but previously difficult to monitor, processes used in the manufacture of integrated circuits. This technique, based on the detection of thermal waves through laser-induced modulation of the sample's optical reflectance, has proven to be an excellent means for detecting and quantifying the extent of lattice damage or disorder in silicon and gallium arsenide wafers that results from chemopolishing, ion implantation and etching processes. This technique thus provides a powerful and cost effective method for monitoring the quality of incoming wafers, the dose and uniformity of ion implantations and the efficiency and uniformity of dry etch processes. Furthermore this method may be used on actual product wafers as well as test wafers since the measurements are performed in a completely nondamaging fashion and with micronscale resolution.

The technique of Auger Electron Spectroscopy has been investigated for the purposes of detecting contamination levels in high dose ion implants. Historically, Auger sensitivities have been considered to be on the order of 1%. This is due to the rather large secondary electron background and the various combinations of electron beam and detector noise that may occur. In this study, it is shown that the use of background subtraction and integration of the resulting EN(E) Auger peak will result in considerably better sensitivities for the case of ion implants in silicon.

It has been well established that sputtering artifacts such as ion beam mixing, preferential sputtering and cone formation ultimately limit interface resolution in Auger and ESCA depth profiling. We have conducted a comparision of the effect of sample rotation, and of the angle of incidence of the ion beam using one and two ion guns on interface resolution. Our investigation has concentrated on the interface resolution and detection of impurities at the various interfaces of a typical semiconductor metallization scheme [Al 700 nm/ TiW 100 nm/ Si02 100 nm/Si]. We have determined that in going from a standard sputtering geometry of a 67 degree tilt from the surface normal to 80 degrees one obtains a factor of five improvement in interface resolution. Sample rotation, on the other hand, was found to improve interface resolution by a factor of two at 67 degrees and to result in minor improvement at 80 degrees. The effect of two ion guns was found to have a negligible effect on the samples studied.

The compositions of sputtered amorphous thin films of Se50Te50, Ge50Te50, and (Te90Ge5 In5)100-x 0 x=0-25 have been measured by electron microprobe x-ray analyzer (EMP) and Auger electron spectroscopy (AES) with sputter depth profiling. Preferential removal of certain elements from the surface region during sputtering is shown to significantly alter the AES-determined surface composition. The effects of sputtering ion mass (He1, Ar1, Xe1), Ar+ energy (1.5 and 4.0 keV), and target temperature (-100 and 25°C) were investigated. The degree of preferential sputtering is found to be controlled predominantly by differences in surface binding energy of the elements with secondary contributions in the case of 0 due to bombarding atom to target atom collisional energy transfer processes.

With X-ray diffraction techniques, it is possible to routinely measure lattice parameters to several parts in 104 for macroscopic specimens. However, measurements of lattice parameter changes for quaternary (InGaAsP) device structures several microns in width are not usually feasible with X-ray diffraction techniques. Convergent Beam Electron Diffraction (CBED), which is one of the techniques available on a modern transmission electron microscope (TEM), may be sensitive to these small, localized lattice parameter changes. Unfortunately, dynamical diffraction effects prevent direct extraction of changes in the lattice parameter from CBED patterns which are obtained from high atomic number materials. For this reason, we have chosen to calibrate the relative position of CBED features with X-ray lattice parameter measurements which were obtained from planar quaternary layers grown on InP substrates. For the active quaternary region of an electro-optical device structure, it is shown that this approach may be sensitive to a relative change in the lattice parameter as small as ±2 parts in 104, which is the uncertainty in the X-ray calibration measurements.

The utility of various electron optical methods to characterize the microstructure and composition of thin films of amorphous silicon-carbon films formed by plasma-activated CVD of SiH4 and CH4 has been investigated. The techniques employed include conventional and high resolution transmission electron microscopy and diffraction, non-dispersive x-ray spectroscopy and electron energy loss spectroscopy.

The effect of uniaxial straining during isothermal heat treatment of a Type 304 stainless alloy has been examined using scanning transmission electron microscopy/energy dispersive x-ray spectroscopy (STEM/EDS) and electrochemical potentiokinetic reactivation (EPR) methods. Solution-annealed, flat tensile specimens were deformed at 600°C at various strain rates up to 6%/h. EPR and STEM/EDS results show an acceleration in sensitization development with increasing deformation. STEM/EDS measurement suggest that simultaneous straining affects both the kinetics of sensitization and the chromium concentrations established at grain boundaries.

We have applied the SEM-EBIC technique (electron-beam-induced current method using a scanning electron microscope) to the characterization of both semiconducting and semi-insulating liquid encapsulated Czocralski (LEC) grown GaAs and have found this technique to be effective for semiinsulating materials as well as semiconducting ones. In semiconducting Si-, In- and undoped LEC-GaAs, growth striations were observed under usual measurement conditions. In semi-insulating undoped LEC-GaAs, clear EBIC images of individual dislocations and cell structures of dislocations were obtained by applying a high reverse bias voltage of about 10∼100 V to the specimens. We have also investigated nearly dislocation-free semiinsulating In-doped LEC-GaAs and found inhomogeneities which are different from those observed in undoped specimens. The spatial resolution of this technique is estimated to be 2–3 μm, which agrees with the experimental result

In many semiconductor materials problems, structural characterizations must be achieved in both the lateral and vertical dimensions. Although a combination of cross-sectional and planar transmission electron microscopy can provide this information, the sample preparation time is demanding and only relatively small volumes of material are examined. We describe here an alternative approach in which the charge collection (‘CCM’) imaging mode of the scanning electron microscope (SEM) is used. It is shown that, by varying the incident electron beam energy, electricallly active defects at different positions beneath the entrance surface of the material can be imaged and their depth estimated.

This study demonstrates a new technique of measuring transport properties of minority carriers by varying the generation rate of the electron-beam induced carriers and measuring the amount of collected charge per incident electron. The technique is suitable. for measurements of very short diffusion length in bulk GaAs material and for measurements in polycrystalline, CVD grown GaAs layers containing grains that are smaller than the diffusion length.

The diffusion length in single crystal GaAs measured at several values of electron-beam energy was.32μm. For l-2μm polycrystalline grains it was found that the diffusion length in the bulk of the. grain can remain high (8μm) but high recombination levels (up to 2 × 106 cm sec−1) prevail at the grain boundaries.

Raman scattering was applied to study mixing of GaAs/AlAs superlattices. Different implantation ions and doses were used. The evolution from partially amorphous to completely amorphous and from partially mixed to completely mixed structures was observed. Rapid thermal annealing caused recrystallization of the damaged material. Different types of structures were obtained, depending on the implantation doses and species of ions. Completely mixed crystalline alloys could be obtained only for high implantation doses.