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Electronic devices fabrication (1) IC wafer - - PowerPoint PPT Presentation
Electronic devices fabrication (1) IC wafer - - PowerPoint PPT Presentation
Electronic devices fabrication (1) IC wafer and looking closer ... and even closer Material: Silicon Technology: planar (epitaxial) Why silicon (wrt. Ge)? - excellent oxide (SiO 2 ) - its a mask for
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… and looking closer… ... and even closer
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Material: Silicon Technology: planar (epitaxial) Why silicon (wrt. Ge)?
- excellent oxide (SiO2)
- it’s a mask for dopants
- excellent dielectric material (for MOSFET gates and
as insulator)
- relatively easy processing
- wider gap ->
less sensitive to T * however, VCEsat is large and carrier mobility is lower
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Planar epitax. technology: how a junction is built
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Short review (anticipation?) on … PN junction inverse saturation current ~ nA breakdown parasitic capacitances BJT C: low doping (to have large Vbr ) B: narrow/short (for speed and gain) E: high doping (to have “good” carriers)
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BJT
- junction isolation
- > n- tank (tub)
- > parasitic C
- buried n+ layer (to have low
Rcoll)
- n+ for C (to avoid Schottky)
+ + +
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More components together...
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CMOS (e.g.: N-well process, poly gate, double metal) (well, there is an error... where?)
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