Sensitive CMOS

[Elektor]

why CMOS IC are so much sensitive towards ESD???????????

 

[Dr.EM]

As far as I know, they have a very thin layer of metal oxide in them, and a high enough voltage can arc through this layer, creating a hole.

 

[fsahmed]

CMOS technology is based upon enhancement type mosfets, which r common mosfets with no pre existing channel. A mosfet, or metal oxide semiconductor has a layer of metal (which serves as gate) which is insulated from the semiconductor by a thin layer of silicon dioxide, SiO2 (hence the name, Metal Oxide Semiconductor Field Effect Transistor: MOSFET).

It is the oxide layer that is sensitive to ESD, it cracks, shorting the gate metal with the semiconductor, turning the mosfet into something like a BJT. BJTs r made to handle current while mosfets r not, so excessive current flowing through the device causes it to blow up. (This may not be very accurate an account of what happens but this is the principle behind it all).

 

[audioguru]

I have been using many Cmoc IC's for about 30 years and there is a lot of static electricity here in Canada in winter. I don't use grounding straps and have never damaged one.
Their sensitive inputs are protected with clamp diodes that aren't big enough to arrest a lightning bolt or strong static arc but they do their job very well. About the only precaution I use is to discharge my body's static first before touching a Cmos IC. :lol:

 

[Screech]

About the only precaution I use is to discharge my body's static first before touching a Cmos IC. :lol:

How do you discharge yourself , Audiguru ?

 

[Styx]

touch/connect to earth

Whenever I am working on my PC I leave it plugged in and turn off the ATX at the rear.
That leaves the earth connected to the case.
IF I built up charge on my in touching the case I discharge myself, IF I then strapp myself in I am tied to earth

For electronics work I have an ESD plug which is just two plastic prong going into LIVE and NEUTRAL but metal going into teh EARTH pin. Then there is a 4mm socket on the front for me to jack into (as well as a mat)