Thanks for all the comments. These were very helpful. Best Regards David Huisman ----------------------------------------------------------------------- ORBIT COMMUNICATIONS Reliable Wireless Solutions (Telemetry, Control, Monitoring ...) Website : http://www.orbitcoms.com PO Box 3469 Tuggerah NSW 2259, AUSTRALIA Phone: 61-2-4393-3627 Fax : 61-2-4393-3685 Mobile: 61-413-715-986 ----- Original Message ----- From: "Alan B. Pearce" To: Sent: Wednesday, April 24, 2002 11:35 PM Subject: Re: [EE]: Xrays and Flash memory > >my next preoccupation would be that during such long exposure or the > >very very high levels encountered in particles in space applications > >would not only transport the gate charge, but also "shoot holes" in the > >semiconductor structure as well. Shielding the entire semiconductor will > >reduce this risk also, but do you have any knowledge of the > >semiconductor being altered in dotation or structure due to radiation > >effects > > I am not aware of such problems, but that is not my area of expertise, I am > an end user of the electronics parts. > > What does happen in some parts is what is termed Single Event Upset (SEU) > where a radiation particle causes the inherent substrate SCR to fire, > creating high currents through the device from the power supply, using > abnormal paths through the device structure. This will cause physical device > failure through localised overheating, and sometimes it is necessary to put > crowbar type protective circuits in the power rails to shut down the power > to a device when this happens. This is usually only required with older PMOS > devices which are very prone to this failure mode. Not normally required > with modern CMOS devices as these are much more radiation hardened. > > The other part of the loop is that devices with small geometries, IIRC > design rules with <2.5u geometries, are inherently radiation hardened > because of their small geometries. This may sound the opposite of what is > sensible, but those who deal with this side of technology tell me it is so. > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > > > --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.338 / Virus Database: 189 - Release Date: 14-Mar-02 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.