The VLSI era will require increased Active Electronic Gate (AEG) density and reduced IC leakage current. The fabrication of circuits to achieve these ends, however, is often accompanied by process-induced defects which degrade the desired circuit characteristics. This brief review will highlight the influence of several point, line and surface defects on the fabrication and electrical characteristics of devices/IC's. Several examples of bulk defect gettering and lithographic processes resulting in unique device/IC configurations to reduce these deleterious effects will then be described.

Formation of buried p-type and n-type layers in silicon by megavolt ion implantation has potential to replace epitaxial growth for buried layer formation. We present arguments for the use of ion implantation for buried layer formation.

The Schottky barrier heights of amorphous Ni₃₆W₆₄ film contacts on n-type and p-type silicon are 0.65 eV and 0.45 eV, respectively. The barrier heights stay constant up to 550°C for a 30 min annealing in vacuum, but the interface, the leakage current, and the ideality factors degrade at 450°C. The contact resistivities of amorphous Ni-W films is (1.4 ± 0.3) 10_-6 Ωcm² on n⁺Si and (8.9 ± 0.2) 10^-7 0cm2 on p⁺Si. The values remain stable after vacuum annealing for 30 min up to 600°C.

This paper reviews our current understanding of the near-noble metal silicides and the interfaces formed with Si(100). Using x-ray photoemission spectroscopy, we compare the chemical composition and electronic structure of the room temperature metal-silicon and reacted silicide-silicon interfaces. The relationship between the interfacial chemistry and the Schottky barrier heights for this class of metals on silicon is explored.

The formation of platinum nickel silicide has been studied by sputter depositing a 600 Å Pt.₄Ni.₆ alloy layer onto (111) n-type Si and annealing for 20 min. in N2 at tempera-tures between 300 and 750°C. RBS, AES and cross-sectional STEM/EDS were used for character-ization. The ternary silicide develops as a two or three layer structure and only at the higher temperatures does a uniform Pt₄Ni.₆Si layer result. An interfacial monosilicide layer containing mostly Ni is present throughout the growth sequence. The silicide growth mechanism can be understood in terms of metal atom diffusion with the preferential bonding of Si to Pt leaving Ni to diffuse deeper into the Si substrate.

Evaporated W ≈ N 3A thick has been used as a diffusion marker during the growth of Pd₂Ge. Pd films ≈ 1200Å thick were vacuum deposited onto Ge < 100 > substrates and annealed in vacuum at temperatures between 230 to 260'C for various times to form the Pd2Ge layer. MeV ⁴He backscattering spectrometry has been used to determine the marker displacement and Pd₂Ge thickness. We find that Pd is the dominant diffusing species, making up about 2/3 of the total atomic transport. We have also measured the Pd₂Ge growth kinetics in this temperature range. We find growth to be proportional to square root of time, i.e. diffusion limited, with an activation energy of 1.08 0.05eV . Thus we find the reaction of Pd with Ge to form Pd₂Ge is very similar to the reaction of Pd with Si to form Pd₂Si.

A review of the techniques developed for using infrared reflection spectroscopy to study properties of heavily implanted semiconductors is presented. Several structural models are considered and calculations based on them are applied to measurements of implanted Si, Ge and GaAs. These comparisons of model calculations and measured spectra show how a number of important physical parameters can be obtained as well as new information concerning implantation-induced amorphous material.

The growth of device quality Al203 dielectric films by an indirect plasma-enhanced CVD technique is described. The films were grown on InP using trimethylaluminum and nitrous oxide reactants in the range of 230-300°C. Direct exposure of substrate to the d.c. generated plasma was minimized by a novel reactor configuration. For optimum deposition conditions, stoichiometric films with indices of refraction between 1.65-1.67 were obtained. InP-M0S capacitors consisting of 1000° thick Al₂0₃ dielectric films and Al-metal field plates showed interface state densities in the range of 3x 10¹¹cm^-2 eV^-1.

The effect of CdS surface orientation on the phase distribution and morphology of the Cu₂S/CdS heterojunction has been investigated. The first high resolution transmission electron microscope (HRTEM) images of Cu₂S/CdS interfaces reveal the presence of the metastable tetragonal phase in heterojunctions formed in terraced CdS surfaces. This observation is rationalized by considering i) the effects of lattice misfit, and ii) the factors influencing the nucleation of h.c.p.-to-f.c.c. transformation dislocations. The implications of this result for the reproducible fabrication of high efficiency Cu₂S/CdS solar cells are discussed.

In this paper, implants of Be, Cd, Si and Se into semi-insulating GaAs as well as the fast diffusion of substrate impurities such as Mn were investigated to establish the profile parameters needed for device applications. Chemical and electrical depth profiles derived from secondary ion mass spectrometry and capacitance-voltage measurements indicate that both Be and Mn diffuse by the donor interstitial-acceptor substitutional mechanism. These conclusions are derived from chemical profiles of Mn in samples implanted with high and low mass donors, Si and Se and light and heavy mass acceptors, Be and Cd. Purity and impurity concentrations in the Be implanted GaAs had marked effects on its post-anneal distribution. A primary factor which influences these profiles is the extent of the host atom damage and the stoichiometric disturbances introduced during the ion implantation process. During the electrical activation of implants by capless controlled atmosphere anneal-ing using AsH₃ in H₂, rapidly diffusing impurities such as Mn can be used to trace the changes in depth of the host atom points defects. The associated diffusions under highly non-equilibrium states are discussed. Our model incorporates the effects of relative damage due to the implant, the effect of Fermi energy on impurity migration and the effect of the arsine overpressure and anneal temperature on the diffusion profiles.

This paper addresses the depth distributions of implanted hydrogen (¹H) in n-type GaAs and the asso-ciated damage in the crystalline material. Secondary ion mass spectrometry measurements are used to demonstrate the presence of hydrogen atoms in the implanted material and to obtain the range profiles of these atoms for fluences of 5E14 and 5E15 cm-2. The nature and the distribution of the resulting lattice damage are studied using transmission electron microscopy. Elevated temperature implants are shown to alter the range profiles and to increase the TEM-visible damage.

The objectives of this paper are three-fold: (1) to describe the necessary conditions for low temperature (i.e. < 500°C) reduction of native oxides from GaAs surfaces; (2) to describe a technique and procedure for establishing those conditions in H2 and possibly N2 gas; and (3) to present results of GaAs native oxide reduction including reduction rates and factors which affect them. Thermodynamic calculations of the necessary ^PH₂0/^PH₂ ratios (equivalent to ^P0₂) for oxide reduction from GaAs are presented. These same conditions would be sufficient to remove native oxides from GaInAs and from Ge. Experimental data will show that these atmospheres can be controlled and measured in flowing H₂ and N₂ through the use of calcia-stabilized zirconia solid electrolytic cells. H₂ atmospheres have been obtained with less than 20 parts per billion of water vapor, low enough to reduce oxides of GaAs at temperatures as low as 270°C. Reduction rates have been determined for an anodic oxide on GaAs indicating that the rate as a function of temperature was proportional to exp(-26600/RT); and it was also directly proportional to the logarithm of the average oxide thickness.

Features and analysis modes of secondary ion mass spectrometry (SIMS) as applied to elemental and compound semiconductors are reviewed. Semiconductor materials are described. The SIMS technique and what it can do are analyzed by examining separately the ion beam, sputtering, the surface, mass analysis, and the secondary ions. Secondary ion enhancement, sputtering rates, impurity - matrix interactions, machine parameters, signal detection modes and dynamic range, depth profile scale calibration, detection sensitivity and depth profile aberrations are discussed. The applications of bulk analysis, imaging, mass scanning, and depth profiling are described. Special capabilities like high mass resolution are pointed out.

The structure of interfaces between silicon oxides grown in dry oxygen on singular and vicinal (111) surfaces of silicon has been studied using cross-sectional high resolution transmission electron microscopy. Crystalline silicon was found to terminate abruptly on (111) planes, where it transforms to amorphous Si0₂. One interplanar distance high ledges, separated by (111) terraces were found to be present on all surfaces studied. The width of the terraces was surface orientation dependent. It is suggested that such a structure of the interface can be explained by a terrace-ledge-kink model and that high temperature oxidation proceeds by a ledge mechanism similar to that for evaporation from the surface.

The major secondary defect in post-annealed 5 x 10¹⁴/cm² As⁺ implanted (111) silicon is microtwins. This was shown to be true for rapid thermal annealing similar to conventional furnace annealing. However, the twin density after rapid thermal annealing to 1100°C for 10 seconds was found to be greater than that in a comparable specimen furnace annealed at 1000°C for 10 minutes. Sheet resistivity after annealing was found to be closely related to the twin density of the specimen. Thermal stress was shown not to be the cause of this increase in twin growth. The higher average crystal regrowth temperature appears to be responsible for growth of more large area twin. Twins of small size were shown to anneal out at high temperature but large area twins did not. Twin free specimens were obtained by regrowth of the amorphous layer at low temperature which formed only small area twins followed by a high temperature anneal which annihilated all the small twins.

This study was directed toward exploring the relationship between the implant conditions and the depth and nature of the amorphous layers generated in silicon. High dose implants of As and P were used to generate buried ane surface amorphous layers at slightly higher than room temperature. The amorphous layer depths were measured and the depth-fluence and depth-energy relationships were compared with Brice's anfiysis. It was found that good fits weri obtained for a threshold damage density of 2.5 x 10²⁰ keV cm^-3 for As and 1.0 x 10²¹ keV cm^-3 for P. Phosphorus ion implantations exhibted a greater tendency to generate buried amorphous layers as well as to generate amorphous layers which included a smaller fraction of the total fluence than was found for As ion implantations.

Research has been conducted in an attempt to correlate the results obtained by cross-sectional transmission electron microscopy (XTEM) to data obtained by angle lapping/ staining (ALS) or Secco etching of various ion implanted specimens. The results indicate that while the stain nearly always delineates the damage or amorphous/crystalline interface, it cannot distinguish between heavily damaged and amorphous regions. An unexpected result was the delineation of deep bands in the implanted wafers 2 to 11 times the LSS projected implantation range (R_p). These bands were found to occur in both neutral and dopant implants and their depth was found to be a mild function of dose but strong functions of temperature and implant ion mass.

Interest in the study of optical properties associated with shallow impurity centers and Wannier excitons in superlattices and quantum well structures is fairly recent. This paper reviews briefly both the theoretical and experimental work done in this field in the last few years. Several recent calculations of the energy levels of hydrogenic impurity states and Wannier excitons in quantum well structures, such as Ga_1-xAl_xAs-GaAs-Ga _1-xAl_xAs, assuming infinite and finite potential barriers at the interfaces are reviewed. The behavior of these levels as a function of the quantum well size is discussed. It is shown that the behavior of the energy states of these shallow systems in finite height potential wells is both qualitatively and quantitatively different from that in infinite height potential wells especially in thin (<100Å) wells. Recent experimental data concerning the variations of the binding energies of shallow acceptors and Wannier excitons as a function of the GaAs quantum well size is reviewed. A comparison between these experimental meas-urements and the results of recent calculations is presented.

The technique of Raman microprobe spectroscopy has been extended to allow polarization sensitive characterization of local crystal quality with lateral mapping capability. Computer minimization algorithms have been utilized to invert Raman scattering intensity versus incident laser polarization information to local crystal orientation. This microprobe method has been applied to investigate the quality of laser annealed polysilicon over oxide films. During the course of laterally seeded epitaxial regrowth of silicon over the oxide film, it was found that the annealed crystal tends to develop large grains of varied size and orientation. Measurements of the local phonon frequency shift, which monitors strain in the material, show large variations across the structures. It is demonstrated that the strain inferred from phonon frequency shifts must be interpreted in terms of the local crystal orientation.

The phosphorus and silicon contents of phosphosilicate glass films deposited by chemical vapor deposition (CVD) on silicon wafers were determined. These films were prepared for use as x-ray fluorescence (XRF) spectrometry standards. The thin films were removed from the wafer by etching with dilute hydrofluoric acid, and the P and Si concentrations in solution were determined by inductively coupled plasma atomic emission spectroscopy (ICP). The calculated phosphorus concentration ranged from 2.2 to 12 wt %, with an uncertainty of 2.73 to 10.1 relative percent. Variation between the calculated weight loss (summation of P₂O₅ and SiO₂ amounts as determined by ICP) and the measured weight loss (determined gravimetrically) aver-aged 4.9 %. Results from the ICP method, Fourier transform-infrared spectroscopy (FT-IR), dispersive infrared spectroscopy, electron microprobe, and x-ray fluorescence spectroscopy for the same samples are compared.

In order to study the mechanisms of acoustooptic interactions in a channel waveguide structure, multimode crossed channel waveguides are fabricated on YZ LiNb0₃ substrate. Besides, an intedigital transduce centered at 320 MHz is made on the same substrate for AO interaction by its generated surface acoustic wave. Butt coupling is used for the coupling between Helium-Neon Laser and channel waveguide. The mode conversion due to the AO interaction in multimode channel waveguide is found. This mode conversions only occur among harmonic modes but not TE to TM modes. Those phenomena are studied and demonstrated theoretically and experimentally. In conclusion, the mode conversion of AO interaction in channel waveguide structure is caused by the acoustic beam spread. This result can be explained by phase matching condition.

The characteristics of oxidation of undoped and heavily phosphorus doped poly-si films deposited by LPCVD has investigated in wide temperature using wet It It is showed that when the oxidation temperature is below 900°C, the characteristics of oxidation is markedly different with that of single-crystalline silicon. For undoped poly-si films, the oxidation is faster not only than (100) si but also than (111) si; for heavily phosphorus doped poly-si films, the oxidation is slower not only than (111) si but also than (100) si. While the range of temperature is 1000-1200°C, it could be described by Deal-Grove model except the initial stage, Xi, is much longer. It is related to, and can be explained by the existance of grain boundaries.