Wafer processing

Four-inch wafer production at CiS includes the usual procedures for monolithic integration of sensor and electronic functions in silicon wafers and chips.

The standard microstructuring procedures at CiS include:

  • High temperature processes (oxidation, oxygen enrichment DO, diffusion, carrier gas diffusion)
  • LP-CVD (silicon nitride, high temperature oxide, poly-silicon, low temperature oxide [doped and undoped])
  • PE-CVD (silicon nitride, oxynitride, silicon oxide)
  • Precision cleaning processes (Carosche acid / piranha solution, RCA, HF, etc.)
  • RIE and plasma etching
  • WET bench (anisotropic silicon etching with and without etch stop, electrochemical isotropic silicon etching),
  • Automatic enamelling and developing cluster, modified for double-sided wafer processing
  • Double-sided adjustment and exposure,
  • Projection lithography based on sodium-free enamel, plus lift-off masks and spray coating
  • Magnetron sputters for metallisation systems (AlSi, TiN, MoSi etc.)

CiS has in addition developed a number of technological modules for double-sided and three-dimensional structuring and provides them for specific applications as technology platforms for R&D work as well as for prototyping and series production:

  • Lift-off masking procedure, especially for non-CMOS-compatible materials (under-bump metallisation Ti-Ni-Au etc.)
  • Spray coating
  • Optimised passivation layers
  • Polymer coating and structuring
  • Three-dimensional modules from combinations of silicon, glass and ceramics can be implemented through wafer level connection and structuring options.

When processing especially radiation-resistant detectors for high-energy physics (e.g. for LHC at CERN), special optoelectronic 3D chip-in-chip modules for precision, route and length measuring as well as piezoresistive highly tensile pressure sensor chips for process measuring, CiS has acquired many years of experience in process integration, based on which we are able to develop new process-ready procedures and technologies and incorporate them in our production lines.