Program Organizers: Jagdish Narayan, Dept of Matls Sci & Engrg, Box 7916, NC State University, Raleigh, NC 27695; John Sanchez, Advanced Micro Devices, M3 160, PO Box 3453, Sunnyvale, CA 94088
Tuesday, PM Room: Orange County 5
February 6, 1996 Location: Anaheim Marriott Hotel
Session Co-Chairs: F. Meyer, University of Paris, Orsay Cedex, France; R. J. Nemanich, North Carolina State Universitiy, Raleigh, NC 27695
2:00 pm Invited
METAL SILICIDES - ACTIVE ELEMENTS OF ULSI CONTACTS: C.M. Osburn, J.Y. Tasi, Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC 27695- 7911
As device dimensions scale to the 0.1 um regeme the self- aligned silicide (SALICIDE) contact technology increasingly becomes an integral part of both the ultra- shallow junction and the MOSFET device itself. This paper will discuss the effect of silicide materials and formation processes on silicide stability, junction consumption, the ability to accurately profile shallow junctions, and contact resistance in series with the channel. The use of silicides as diffusion sources (SADS) provide an important pathway towards optimization silicide technology. Diffusion of boron and arsenic from nearly epitaxial layers of CoSi2, formed with bilayers of Ti and Co, offer good silicide stability, ultra-shallow, low-leakage junctions, and low contact resistance.
2:30 pm
STUDIES ON GRAIN GROWTH AND WETTING BEHAVIOR OF AN Cu- Sn ALLOY AND PURE Cu FOR ADVANCED CHIP INTERCONNECTS: J. Zhang, H.K. Kim, K.N. Tu, Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095
Copper- Tin alloys have been studied as interconnects for advanced device applications where a high resistance to electromigration is required. A bulk Cu2 at.% Sn alloy was prepared and used to study the effect of Sn on Cu grain growth. The alloy was heat- treated at 700, 800, and 900deg.C and the average grain sizes, grain morphology and orientation were quantified and compared with those of pure Cu. No secondary grain growth in the Cu- Sn alloy was observed, in contrary to pure Cu. The grain growth rate and mechanism in both systems will be discussed. A comparison of wetting behavior of eutectic SnPb solder on both materials will also be given.
3:00 pm Invited
EPITAXIAL TiN BASED CONTACTS FOR SILICON DEVICES: J. Narayan, R. D. Vispute, Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695- 7916
Fabrication of modern integrated circuits heavily relies on TiSi2 compound (C- 54 phase with specific resistivity of 15-cm) and an orthorhombic structure (a=0.825, b= 0.478, c=0.854 nm). However, this structure is incompatible with diamond cubic, and, therefore, it is not be able to grow epitaxially on silicon (a=0.543 nm). The polycrystalline TiSi2 films have the following problems: (i) interface roughness, and (ii) grain boundaries along which dopants diffuse out. Recently, we have grown epitaxial TiN/Si(100) and multilayerd epitaxial Cu/TiN/si(100) heterostructures by domain matching epitaxy where four lattice units of TiN match with three of silicon, and six units of TiN match with seven units of copper (Narayan, US Patent # 5406123, Apnl 11, 1995). We also found that epitaxial TiN has 15 - cm resistivity with excellent barrier properties. In addition, Schottky barrier height of TiN is close to that of TiSi2 (0.SeV). Thus for next generation device CMOS structures, Cu/TiN/Si(100) contacts hold considerable promise, particularly since Cu is a low resistivity metal (2- cm) and is resistant to electromigration.
3:30 pm BREAK
4:00 pm Invited
MICROSTRUCTURE AND ELECTRICAL PROPERTIES OF SrRuO3 THIN FILMS ON LaAlO3 SUBSTRATES: F. Chu ,Q.X. Jia, X.D. Wu, T.E. Mitchell, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos NM 87545
Conductive oxide SrRuO3 thin films have been deposited using pulsed laser deposition on LaAlO3 substrates at different substrate temperatures. Structural and microstructural properties of the SrRuO3/LaAlO3 system have been studied using xray diffraction and scanning electron microscopy. Electrical properties of SrRuO3 thin films have been measured. It was found that the film deposited at 250deg.C is amorphous, showing semiconductor- like temperature dependence of electrical conductivity. The film deposited at 425deg.C is crystalline with very fine grain size (100~200A), showing both metallic and semiconductor- like temperature dependence of the electrical conductivity in different temperature regions. Epitaxial [001] growth of the films takes place above 650deg.C deposition temperature. The film deposited at 775deg.C shows a resistivity of 280 u[[Omega]]- cm at room temperature. The optimized deposition conditions to grow SrRuO3 thin films on LaAlO3 substrates have been found. Possible engineering applications of SrRuO3 thin films deposited at different temperatures will be discussed.
4:30 pm
LaNiO3 AND Cu3Ge CONTACTS lN YBa2Cu3O7- FILMS: D. Kumar, R.D. Vispute, O. Aboelfotoh, S. Oktyabrsky , J. Narayan, Department of Materials Science and Engineering, North Carolina State University Raleigh, NC 27695- 7916; P.R. Apte, R.Pinto, Tata Institute of Foundamental Research, Bombay, India
Epitaxial LaNiO3 (LNO) metallic oxide thin films have been grown on YBa2Cu3O7-x(YBCO) films at 700[[ring]]C using pulsed laser evaporation technique. The sheet resistance of LNO films was measured to be 2[[Omega]]/square at 300 K which decreases to 0.75[[Omega]]/square at 100K indicating good metallicty of LNO films. The contact resistance of LNO- YBCO thin film interface was found to be reasonably low (of the order of 10- 4 [[Omega]]cm2 at 77 K) which suggests that interface formed between the two films is quite clean and LNO can emerge as a promising metal electrode- material to YBCO films. A preliminary investigation related to chemical compatibility of Cu3Ge as an alternative metallic electrode to YBCO films would also be presented.
5:00 pm
THERMOMECHANICAL FATIGUE BEHAVIOR OF LAP SHEAR JOINTS: R.K. Mahidhara, S. Hariprasad, High Performance Materials Inc., Campus Box 1087, B. Goldstein, S.M.L. Sastry, K.L. Jerina, Mechanical Engineering Department, Campus Box 1185, Washington University, St. Louis, MO 63130
Abstract not available.
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