Materials used for fabricating devices:

• classification on engineering use: metallic (Al, Cu, Au), polymers, ceramics, organic, alloys (Ni-Fe, Pb-Sn), piezoelectrics (ZnO), superconductive materials (YBa₂Cu₃O_7-x)
• classification on structure: amorphous (no long range order), polycrystalline, monocrystalline
• classification on conductivity: conductors, semiconductors, dielectric
• classification on mechanical properties: brittle or easily stretched
• classification on optical properties: reflective or transparent

LARGE DIVERSITY due to various composition, bonding, structure.

Examples:

• Single crystalline silicon is the most important
  • Fabrication: Czocharalski method, Floating zone method, epitaxial
• Polysilicon
• has a columnar structure
• grain size of 1 micron
• inside the grain the material is crystalline
• the neighbouring grains have various crystalline orientations
• the grain boundaries have deletorious effect upon conductivity, due to high density of traps
• deposited by LPCVD at 600oC
• Silicon dioxide
  • grown at 1000oC in furnace
  • deposited at lower temperature with plasma but worse properties
• Silicon nitride
  • insulator with high intrinsic stress (solved for Si rich films) deposited at 800oC
• Silicides
  • alloys between silicon and metals MoSi₂, WSi₂, TaSi₂, TiSi₂, PtSi, PdSi₂
  • fabricated by sputtering and CVD
• Metals
  • aluminium and Cu (for electrical interconnections), FeNi, Pa, Pl (for sensors and actuators)
  • PVD, CVD, electroplating - are the main fabrication methods
• Organic layers
  • photoresist, passivation layer
  • separation of DNA and proteins in nanotechnology