R. A. Levy

Amorphous magnetism--II

Survey of Theories of Spin Glass.- Some Percolation Scaling Applications to Low Temperature Dilute Magnets.- + Studies of Dilute PdFe Alloys.- Spin Waves in Heisehberg Spin Glasses.- Temperature-Dependent Skew Scattering in an AuMn Spin Glass.- Slowly Relaxing Remanence and Metastability of Spin Glasses.- Effective Field Theories of Topologically Disordered Magnets.- Spin Glasses and Mictomagnets - Revisited.- Concentration Effects in Spin Glasses.- Effect of Pressure on Impurity-Impurity Interactions in Spin Glass Alloys.- Critical Properties of a Simple Glass Model.- Magnetic Ordering of AuCr: An Ultrasonic Investigation.- Two Approaches to the Theory of Spin Glasses: A Comparison with Each Other and with Experiment.- Localized Moment and Spin-Glass-Like Behavior in Amorphous YFe2.- Real Space Renormalization Group Calculations for Spin Glasses.- The Remanent Magnetization of Spin Glasses and the Dipolar Coupling.- The Magnetic Behavior of Pd-Mn Alloys.- Some Controversial Aspects of Electronic and Magnetic Interactions in the Amorphous Metallic State.- Magnetic Susceptibility of an Amorphous Non-Transition Metal Alloy: Mg 70Zn 30.- 31P Nuclear Magnetic Resonance Study in the Metallic Glass Systems (Niy Pt1?y), 75P25 and (Ni0.50Pd0.50)100?xPx.- NMR and Mossbauer Studies of the Amorphous System Fe79P21?xBx+.- Magnetism in Amorphous Zr-Cu(Fe), Zr-Cu(Gd), and Nb-Ni(Fe).- From Superconductivity to Ferromagnetism in Amorphous Gd-La-Au Alloys.- The High Temperature Electronic and Magnetic Properties of Pd-Alloys in the Glassy, Crystalline and Liquid State.- Ferromagnetic and Antiferromagnetic Coupling in Amorphous (Ni100-cMnc)78P14B8.- Electronic and Magnetic Properties of Amorphous Fe-P-B Alloys.- Mossbauer Study of a Glassy Fe80B20 Ferromagnet.- The Resistivity of Amorphous Ferromagnets.- Magnetic Regimes in Amorphous Ni-Fe-P-B Alloys.- Resistivity of Metglas Alloys From 1.5 K to 800 K.- Electrical Resistivity and Crystallization of Amorphous Metglas 2826 and Metglas 2826A.- Transformation of Some Amorphous FePC Alloys During Isothermal Aging.- Perspective on Application of Amorphous Alloys in Magnetic Devices.- High Magnetic Permeability Amorphous Alloys of the Fe-Ni-Si-B System.- Magnetostriction of Metallic Glasses.- On the Magnetically Induced Anisotropy in Amorphous Ferromagnetic Alloys.- Application of Domain Wall Pinning Theory to Amorphous Ferromagnetic Materials.- Magnetic Characterization of Semi-Amorphous Nickel on Alumina Dispersions: Correlations with Their Methanation and Chemisorption Activities.- Surface Effects in Amorphous Ferromagnets with Random Anisotropy.- Spin Wave Excitation and Propagation in Amorphous Bubble Films.- Temperature Dependence of the Extraordinary Hall Effect in Amorphous Co-Gd-Mo Thin Films.- Current Views on the Structure of Amorphous Metals II.- Structure Simulation of Transition Metal - Metalloid Glasses, II.- Structural Models for Amorphous Transition Metal Binary Alloys.- Small-Angle Magnetic Scattering in Amorphous TbFe2.- Magnetism and Structure of Amorphous Fe80P13C7 Alloy.- The Magnetic and Electronic Properties of Amorphous Nickel Phosphorus Alloys.- Structure and Physical Properties of an Amorphous Cu57Zr43 Alloy.- A Proposed Structure Model for Amorphous Pd0.8Si0.2 Alloy.- Ground State of an Ising Antiferromagnet with a Dense Random Packing Structure.- Magnetic Resonance and Glass Structure.- Magnetic Susceptibility and EPR Studies of Reduced Titanium Phosphate Glass.- Characterization of Ferromagnetic Precipitates in Glass by Ferromagnetic Resonance.- Low Temperature Thermal Conductivity of MnO*Al2O3*SiO2 Glass.- A Calorimetric Investigation of a CoO*Al2O3*SiO2.- Exchange Fields and Crystal Fields in CoO*Al2O3*SiO2 Glass: A Mossbauer Study.- Oxidation - Reduction Equilibrium in Glass Forming Melts.- Effect of Temperature and Oxygen Partial Pressure on Coordination and Valence States of Fe Cations in Calcium Silicate Glasses - A Mossbauer Study.- A Mossbauer Study on the Clustering and Crystallization Phenomena in BaO-4B2O3 Glasses Containing Dilute Concentrations of Fe2O3.- Magnetic Properties of (Fe2O3-TiO2) in BaO-B2O3-SiO2 Oxide Glasses.- Magnetic Properties of an Iron Borosilicate Glass.- Paramagnetic Impurity Concentrations in Amorphous Polymers.- List of Participants.

Characterization of LPCVD Aluminum for VLSI Processing

Aluminum and aluminum alloys are widely used for metallizing devices in VLSI processing. Such films can be deposited by a variety of techniques, which all presently suffer from inadequate step coverage. In this paper, we discuss the properties of aluminum films deposited by a low pressure chemical vapor deposition process using tri‐isobutyl aluminum as a source. Results of this work demonstrate that this process provides conformal step coverage, introduces no surface states, and promises to yield high wafer throughput. Films deposited on oxidized silicon monitors exhibit excellent properties in terms of chemical purity, adhesion, and electrical resistivity. Films deposited on device wafers prove to be compatible with current VLSI processing in terms of patterning, dry etching, and bondability and appear to have no effect on overall device performance. However, drawbacks of LPCVD aluminum appear to be in its structure‐related properties: namely, electromigration resistance and Al‐Si interdiffusion. These problems and potential solutions are addressed.

Aluminum films prepared by metal-organic low pressure chemical vapor deposition

Abstract In this study, we have chemically vapor deposited aluminum films by the pyrolysis of triisobutylaluminum, an aluminum alkyl, at temperatures of 220–300 °C onto silicon, SiO2 and device wafer substrates. The step coverage of our films is good, as demonstrated by our ability to deposit films conformally in the 2.5 μm windows of a typical device. The optical reflectivity of the films is low because of surface roughness of the order of 1000–1500 A, which also renders them frosty in appearance. The films are highly pure aluminum with resistivities ranging between 2.8 and 3.5 μΩ cm. Transmission electron microscopy examination of the films shows them to be composed of columnar grains 1–3 μm in width, whcch may either be strongly oriented with a 〈111〉 fiber texture or be randomly poriented, depending on the surface activation treatment. Chemically vapor-deposited aluminum films have potential as metallizations for future generations of very-large-scale integrated devices.

Microelectronic materials and processes

1 Silicon Crystal Growth.- 1.1 Introduction.- 1.2 Growth Characteristics.- 1.3 Impurity Incorporation.- 1.4 Trends in Large-Diameter Silicon Growth.- 1.5 Conclusions.- 2 Silicon Epitaxy.- 2.1 Introduction.- 2.2 EPI Equipment.- 2.3 Deposition.- 2.4 Doping.- 2.5 Autodoping.- 2.6 Pattern Shift.- 2.7 Defects.- 2.8 EPI Characterization.- 2.9 Conclusions.- 3 Silicon Oxidation.- 3.1 Introduction.- 3.2 Oxide Formation.- 3.3 Silicon Dioxide Properties.- 3.4 Conclusions.- 4 Physical Vapor Deposition.- 4.1 Introduction.- 4.2 Deposition Methods.- 4.3 Alloys and Compounds.- 4.4 Film Properties.- 4.5 Conclusions.- 5 Chemical Vapor Deposition.- 5.1 Introduction.- 5.2 Some Basic Aspects of CVD.- 5.3 Types of CVD Processes.- 5.4 Production CVD Reactor Systems.- 5.5 Deposition of Various Materials for VLSI Device Fabrication.- 5.6 Conclusions.- 6 Dielectric Materials.- 6.1 Introduction.- 6.2 Dielectric and Insulator Materials and their Applications in VLSI Technology.- 6.3 Methods of Film Formation and Equipment.- 6.4 Vertical Insulation in VLSI Technology.- 6.5 High Temperature Interconductor Insulation.- 6.6 Low Temperature Intermetal Insulation.- 6.7 Over-Metal Passivation Layer.- 6.8 Conclusions.- 7 Properties and Applications of Suicides.- 7.1 Introduction.- 7.2 Properties.- 7.3 Formation of Suicides and their Processing.- 7.4 Process Stability of Silicides-Resistivity, Stress and Device Reliability.- 7.5 Limitations.- 7.6 Conclusions.- 8 Forefront of Photolithographic Materials.- 8.1 Introduction.- 8.2 Extending Positive Resist Performance in the UV Region.- 8.3 Negative Resist Materials Which Do Not Swell During Development.- 8.4 Image Reversal Techniques.- 8.5 Contrast Enhancing Materials (CEMs).- 8.6 Amplification in Photoresist Technology.- 8.7 Deep UV Resists.- 8.8 Multilevel Resist Technology and Planarization.- 8.9 Bilayer Resist Processes.- 8.10 Gas-Phase-Functionalized Plasma-Developed Resists.- 8.11 Conclusions.- 9 Fine-Line Lithography.- 9.1 Introduction.- 9.2 Basic Fabrication Processes and Ultimate Resolution.- 9.3 UV Shadow Printing.- 9.4 X-Ray Lithography.- 9.5 Ion and Electron Beam Proximity Printing.- 9.6 Optical Projection.- 9.7 Scanning Electron Beam Lithography.- 9.8 Scanning Ion Beam Lithography.- 9.9 Conclusions.- 10 Dry Etching Processes.- 10.1 Introduction.- 10.2 RF Glow Discharges (Plasmas).- 10.3 Etching Considerations.- 10.4 Profile Control.- 10.5 Process Monitoring (Diagnostics).- 10.6 Other Dry Etch Techniques.- 10.7 Radiation Damage.- 10.8 Safety Considerations.- 10.9 Conclusions.- 11 Ion Implantation.- 11.1 Introduction.- 11.2 Ion Implanters.- 11.3 Range Distributions.- 11.4 Ion Damage.- 11.5 Annealing of Implanted Dopant Impurities.- 11.6 Ion Beam Annealing.- 11.7 Conclusions.- 12 Diffusion in Semiconductors.- 12.1 Introduction.- 12.2 Phenomenological Description.- 12.3 Point Defects and Atomistic Diffusion Mechanisms.- 12.4 Diffusion in Silicon.- 12.5 Diffusion in Germanium.- 12.6 Diffusion in Gallium Arsenide.- 12.7 Conclusions.- 13 Interconnect Materials.- 13.1 Introduction.- 13.2 Material and Process Requirements for VLSI Technology.- 13.3 Gate Metallization.- 13.4 Metal-Silicon Contacts.- 13.5 Interconnect Lines.- 13.6 Conclusions.- 14 Imperfection and Impurity Phenomena.- 14.1 Introduction.- 14.2 Imperfections and Impurities.- 14.3 Electrical Phenomena.- 14.4 Defect-Free Processing.- 14.5 Conclusions.- 15 Process Simulation.- 15.1 Introduction.- 15.2 Epitaxy.- 15.3 Ion Implantation.- 15.4 Diffusion.- 15.5 Lithography.- 15.6 Conclusions.- 16 Diagnostic Techniques.- 16.1 Introduction.- 16.2 Physical Background of Diagnostic Techniques.- 16.3 Analytical Aspects of Diagnostic Techniques.- 16.4 Areas of Application of Diagnostic Techniques.- 16.5 Specific Features and Applications of the Different Methods.- 16.6 Conclusions.- 16.7 Explanation of Acronyms and Abbreviations.

Synthesis and characterization of low pressure chemically vapor deposited titanium nitride films using TiCl4 and NH3

Abstract This study investigates the inter-relationships governing the growth kinetics, composition, and properties of titanium nitride (TiN) films synthesized by low pressure chemical vapor deposition (LPCVD) using titanium tetrachloride (TiCl 4 ) and ammonia (NH 3 ) as reactants. In the deposition temperature regime of 450 to 600 °C, an Arrhenius dependence was observed from which an activation energy of 42 kJ/mol was calculated. The growth rate dependencies on the partial pressures of NH 3 (50 to 100 mTorr) and TiCl 4 (1 to 12 mTorr) yielded reaction rate orders of 1.37 and −0.42, respectively. RBS spectrometry was used for establishing the Ti/N ratio and the chlorine content of the films as a function of the processing variables. Films with compositions trending towards stoichiometry were produced as the deposition temperature was decreased and the NH 3 partial pressure was increased. The chlorine concentration in the films was observed to decrease from 7.2% ( a / o ) at the deposition temperature of 450 °C down to 0.15% at 850 °C. The film density values increased from 3.53 to 5.02 g/cm 3 as the deposition temperature was increased from 550 to 850 °C. The resistivity of the films was dependent on changes in deposition temperature and flow rate ratios. The lowest resistivity value of 86 μΩ cm was measured for a deposition temperature of 600 °C and an NH 3 /TiCl 4 flow ratio of 10/1. The film stress was found to be tensile for all deposits and to decrease with higher deposition temperatures. Nano-indentation measurements yielded values for the hardness and Youngs modulus of the films to be around 15 and 250 GPa, respectively. X-ray diffraction measurements revealed in all cases the presence of cubic TiN phase with a preferred (200) orientation. For the investigated aspect ratios of up to 4:1, the deposits were observed to exhibit conformal step coverage over the investigated range of processing conditions.

A new LPCVD technique of producing borophosphosilicate glass films by injection of miscible liquid precursors

This study introduces a new, simple, and viable LPCVD technique based on the injection of miscible liquid precursors. The preparation of BPSG films from liquid mixtures of TEOS, TMB, and TMP is used here as a prime example for implementing this concept. The relationship between starting solution composition and resulting film composition is investigated to provide guidelines for achieving desired stoichiometries. Variations in growth rate and composition are examined to assess the relative effects of deposition temperature, total pressure, solution composition, and injection rate. At the high boron and phosphorus levels (greater than or equal to4 weight percent), the reaction chemistry associated with the use of TMP is seen to produce severe depletion effects. At optimum deposition conditions, select properties of BPSG films are investigated. The results indicate high compositional uniformity within the film, a dielectric constant value in close agreement with that of thermally grown, SiO/sub 2/, conformal step coverage even in the case of severe aspect ratios, and desirable flow profiles at temperatures and phosphorus concentrations significantly lower than those being currently achieved with phosphosilicate glass films.

Twin-Tub CMOS II-An advanced VLSI technology

An advanced CMOS technology has been developed for the fabrication of VLSI circuits having 2.5 µm features. The structure uses Twin-Tubs in a lightly-doped n-epitaxial layer over an n+-substrate2. Local oxidation and self-aligned chan-stops provide device isolation. The gate level has a nominal sheet resistance of 2.5Ω/□ and consists of a composite layer of TaSi2over n+polysilicon. The gate oxide is 350 Å thick, and the electrical channel lengths for the n- and p-channel transistors are nominally 1.5 µm The threshold voltages of the n- and p-channel devices are 0.7V and -1.1V respectively. A compensating threshold-adjustment implant is used to tailor the p-channel threshold voltage. The limitations and advantages of this technique are addressed here. We present the process highlights discuss the device properties and present some of the applications of this technology.

Reduced thermal processing for ULSI

As feature dimensions of integrated circuits shrink, the associated geometrical constraints on junction depth impose severe restrictions on the thermal budget for processing such devices. Furthermore, due to the relatively low melting point of the first aluminum metallization level, such restrictions extend to the fabrication of multilevel structures that are now essential in increasing packing density of interconnect lines. The fabrication of ultra large scale integrated (ULSI) devices under thermal budget restrictions requires the reassessment of existing and the development of new microelectronic materials and processes. This book addresses three broad but interrelated areas. The first area focuses on the subject of rapid thermal processing (RTP), a technology that allows minimization of processing time while relaxing the constraints on high temperature. Initially developed to limit dopant redistribution, current applications of RTP are shown here to encompass annealing, oxidation, nitridation, silicidation, glass reflow, and contact sintering. In a second but complementary area, advances in equipment design and performance of rapid thermal processing equipment are presented in conjunction with associated issues of temperature measurement and control. Defect mechanisms are assessed together with the resulting properties of rapidly deposited and processed films. The concept of RTP integration for a full CMOS device process is also examined together with its impact on device characteristics.

Modeling of boron and phosphorus implantation into (100) Germanium

Boron and phosphorus implants into germanium and silicon with energies from 20 to 320 keV and ion doses from 5/spl times/10/sup 13/ to 5/spl times/10/sup 16/ cm/sup -2/ were characterized using secondary ion mass spectrometry. The first four moments of all implants were calculated from the experimental data. Both the phosphorus and boron implants were found to be shallower in the germanium than in the silicon for the same implant parameters and high hole concentrations, as high as 2/spl times/10/sup 20/ cm/sup -3/, were detected by spreading resistance profiling immediately after boron implants without subsequent annealing. Channeling experiments using nuclear reaction analysis also indicated high substitutional fractions (/spl sim/19%) even in the highest dose case immediately after implant. A greater straggle (second moment) is, however, observed in the boron implants in the germanium than in the silicon despite having a shorter projected range in the germanium. Implant profiles predicted by Monte Carlo simulations and Lindhard-Scharff-Schiott theory were calculated to help clarify the implant behavior. Finally, the experimentally obtained moments were used to calculate Pearson distribution fits to the boron and phosphorus implants for rapid simulation of nonamorphizing doses over the entire energy range examined.

Implantation and activation of high concentrations of boron in Germanium

There is renewed interest in the development of Ge-based devices. Implantation and dopant activation are critical process steps for future Ge devices fabrication. Boron is a common p-type dopant, which remarkably is active immediately after implantation in Ge at low doses. This paper examines the effect of increasing dose (i.e., 5/spl times/10/sup 13/-5/spl times/10/sup 16/ cm/sup -2/) and subsequent annealing (400/spl deg/C-800/spl deg/C for 3 h in nitrogen) on activation and diffusion of boron in Ge. Secondary ion mass spectrometry (SIMS), spreading resistance profiling (SRP), high resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA) are used to characterize the implants before and after annealing. It is found that very high fractions of the boron dose (/spl sim/5%-55%) can be incorporated substitutionally immediately after implantation leading to very high hole concentrations, /spl ges/2/spl times/10/sup 20/ cm/sup -3/, deduced from SRP. Small increases in activation after annealing are observed, however, 100% activation is not indicated by either SRP or NRA. Negligible diffusion after annealing at either 400/spl deg/C or 600/spl deg/C for 3 h was, furthermore, observed.