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Tutorial Course Descriptions

Detailed Syllabus

C-315 Reactive Sputter Deposition

This tutorial covers the fundamental mechanisms and technology of high rate reactive sputter deposition of conducting and insulating thin films. Following a brief introduction to reactive sputtering, including discussion of basic issues, target choices, and system configurations, we examine the effects of reactive gas addition on target surface and glow discharge processes which control film growth rates. Deposition approaches used in reactive sputtering – dc, rf, magnetron, pulsed dc, and ion beam – are discussed and compared. Process control strategies (e.g.: flow, partial pressure, and target voltage, and multi-loop control) and their implementation are described in detail using numerous examples. The advantages and disadvantages of these different modes of operation are examined from the point of view of controlling film properties. Emphasis is placed on developing a sufficient understanding of reactive sputter deposition to provide direction in designing new processes. The effects of energetic particle irradiation (positive and negative ions and fast neutrals) on film properties are also discussed. Present and future trends in reactive sputter deposition are addressed.

 

Topical Outline:
  • Introduction to reactive sputter deposition of conducting and insulating thin films
  • Target processes during reactive sputtering
  • Glow discharge volume processes during reactive sputtering
  • Deposition technologies used in reactive sputtering (dc, rf, magnetron, pulsed dc, ion beam)
  • Process control strategies
  • Particle irradiation effects during film growth
  • Film properties
  • Computer-based modeling
Course Details:

Preface

  • Useful data (periodic table, sputtering yield curves)
  • Physical constants
  • Selected unit conversions
  • Selected relationships (ideal gas law, mean free paths, momentum transfer)


Review of sputter deposition and introduction to reactive sputtering

  • General reference lists for sputter deposition and reactive sputtering
  • Mechanisms of sputtering (definition, ion/surface interactions, yields)
  • Fundamental sputter deposition technologies (dc, rf, magnetron)
  • Reactive sputtering (system configurations, issues, categories)
o example applications
o target choice (metal vs compound)
o film properties (electrical, mechanical, optical, nanostructures)


Target processes during reactive sputtering

  • High deposition rates: the fundamental issue
  • Metal/gas systems (exs: Ti/N2, Al/O2, Al/N2, Cr/O2, Ti/O2, V/N2, V/O2, Zr/N2)
o materials dependence (e.g., In/N2 vs In/O2)
o secondary electron yields
  • Metal/metalloid systems (ex.: Ti/B2H6, TiB2/Ar, GaAs/As4)
  • Arcing (ex: Al/O2)
  • Negative ions (exs: Al/O2, In/O2, Zn/O2, YBa2Cu3O7-x, PbZr0.5Ti0.5O3, BaCu2Ox)

Gas phase processes during reactive sputtering

  • Ionization cross-sections: rare gases
  • Ionization cross-sections: reactive gases
  • Charge exchange cross-sections
  • Glow discharge volume processes
  • Gas phase transport of sputtered species (preferential scattering, preferential resputtering, preferential resputtering with segregation, gas rarefaction)

Process control strategies during metal/gas reactive sputtering

  • Introduction and history: high pumping speeds, baffled systems, and gas pulsing (exs:Ti/N2, Al/O2)
  • Process control strategies
  • Flow control (exs: Ti/N2, Ti/O2, CdSn2/O2, Al/O2, Cr/O2, Zn/O2)
    o two reactive gases (ex: Si/N2+O2)
  • Partial pressure control (exs: Ti/N2, Ti/O2, Al/O2, Cr/O2, Zr/O2, Zn/N2, Hf/N2, Zr/N2)
    o two reactive gases (ex: Ti/N2+O2)
  • Target voltage control (ex: Al/O2)
  • Compositional uniformity, manifold design and gas distribution (exs: Al/O2, Si/O2)


Process control strategies during metal/metalloid reactive sputtering

  • The issue
  • Examples: TiB2, GaAs
  • Process control methods
  • High rate sputtering


Reactive sputtering of insulators: pulsed dc and mid-frequency ac

  • Fundamental issues (ex: Al/O2)
o arc and droplet formation: mechanisms and estimate of minimum frequency to quench arcs (example: Al/O2)
o solutions: rf, symmetric and asymmetric pulsed dc, mid-frequency ac
  • Asymmetric bipolar pulsed dc (exs: Al/O2, Al/N2)
o mechanisms of operation, characteristics, and waveforms (exs: Al/O2, Al/N2)
o duty cycle effects (examples: Al/O2, Al/N2)
o advantages and disadvantages: redundant anode
o pulsed dc substrate biasing
  • ac mid-frequency dual target reactive sputtering
o mechanisms of operation, characteristics, waveforms (exs: Al/O2, Al/N2, Si/O2)
o advantages and disadvantages
o substrate heating (exs: Al/Ar, Al/N2)
  • Symmetric pulsed dc dual target sputtering
o mechanisms of operation, characteristics, waveforms (exs: Al/O2, Ti/O2)
o advantages and disadvantages
o alloys (exs: TiSi/O2)


Computer-based modeling

  • Metal/gas systems
o early models and recent models including gas flow
o origin of hysteresis effects
o multi-phase materials (e.g.: Cr in Ar/N2)
o two reactive gases
o co-sputtering from two targets vs alloy targets
  • Metal/metalloid systems (examples: Ti in Ar/B2H6 and GaAs in Ar/As4)

Instructor: Joe Greene, Willett Professor of Materials Science and Physics, University of Illinois
Joe Greene

is the D.B. Willett Professor of Materials Science and Physics, the Tage Erlander Professor of Materials Physics at Linkoping University, a Chaired Professor at the National Taiwan University of Science and Techology, and Past Director of the Frederick Seitz Materials Research Laboratory at the University of Illinois. The focus of his research has been the development of an atomic-level understanding of adatom/surface interactions during vapor-phase film growth in order to controllably manipulate microchemistry, microstructure, and physical properties. His work has involved film growth by all forms of sputter deposition (MBE, CVD, MOCVD, and ALE). He was President of the American Vacuum Society in 1989, a consultant for several research and development laboratories, and a visiting professor at several universities. Recent awards include receipt of the Aristotle Award from SRC (1998), the Adler Award from the American Physical Society (1998), Fellow of the American Vacuum Society (1993) and the American Physical Society (1998), the Turnbull Prize from the Materials Research Society (1999), Fellow of the Materials Research Society (2013), and the Mentor Award from SVC (2015). He was elected to the US National Academy of Engineering in 2003 and is the Editor-in-Chief of Thin Solid Films.


This course is currently available via:
On Location Education Program

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