Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Technology Stocks : Advanced Micro Devices - Moderated (AMD) -- Ignore unavailable to you. Want to Upgrade?

To: jeff_boyd___ who wrote (21492)	12/4/2000 8:01:04 PM
From: Gopher Broke	Respond to of 275872

jeff, I believe that the ISON changes are not related to SOI. SOI requires a completely new process, whereas, as I understand it, the isotopically pure silicon has such similar properties to the impure stuff that it is just a question of replacing your wafers with the special high-conductivity ones.

To: jeff_boyd___ who wrote (21492)	12/4/2000 9:09:56 PM
From: Bill Jackson	Respond to of 275872

jeff, ISON makes isotopically pure Si28. Silicon(Si) as found as natural compounds is a mixture of Si 28,29 and 30. These are all natural stable elements. no radiation. they vary only in their atmic weight. Their atomic number is the same thuse they are chemically identical(almost). The small differences show up when you make a regular crystal from the Si that is very pure and you cut your wafers from it to make CPUs. As you follow the crystal reggularity you find mostly Si28 with a scattering of Si29 and Si30 in there. This has the ability to interfere with heat conduction, slowing it down. From their web site they mention phonon-electron interactions. Phonons are sound quanta and I surmise that the most regular the Si grid the further the phonons travel before interacting with electrons(I am a bit vague on this.....anyone??) This increase in the mean free path of the phonons traslates into increased heat flow. So the CPU on the wafer makes heat and it travels down through the Si substrate of the flip chip and into the heat transfer compound and through that into the copper heat spreader. The better the Si is at heat conduction and the thinner the heat transfer compound and the better the heat transfer compound does it's heat transfer job....the more heat can be taken away from the CPU. This means the CPU can run faster. Hence AMD can make a faster CPU since they can remove the larger heat flow that comes from faster CPUs. Now SOI is silicon on insulator and in a way this interferes with heat flow. the insulator allows the CPU to run faster by lowering the capacitive coupling to the substrate. That also means faster CPUs. By using an insulation with bibbles in it to lower the K factor they can make faster CPUs. Trouble is bubbles hinder heat flow as the place a has in the way of the heat flow. Still you can have SOI together with Si28 and it becomes a problem of iteratively approaching the optimum balance between all the factors. Bill.