How they make silicon wafers

[GaryB]

Is it true that the transistor elements in today's CPUs are Mosfets in essence?

Yes - all the transistors in a CPU are MOSFETs.

From a structural point of view the transistors in a CPU are MOSFETs. But the gate is not made from metal but from "poly-silicon".

Maik,
Your answer is accurate but probably causes some confusion to the typical diyaudio reader. Here's how I would answer it.

MOSFET = Metal Oxide Semiconductor Field Effect Transistor

Almost every mosfet built on silicon until very recently has used polycrystalline silicon (aka polysilicon) as the gate conductor or the metal in the MOSFET stack. The polysilicon is doped very heavily with an n-type impurity (typically phosphorus) so that it behaves like a metal. It is sometime also clad with a metal to further lower the resistance of the gate.
So CPU transistors are true MOSFETs.

In the 45nm and 32nm generations, Intel introduced a true metal gate electrode and also switched the dielectric from silicon dioxide (SiO2) to a metal oxide with a higher dielectric than SiO2. This was key to improving performance and lowering power of the latest generations of CPUs.

---Gary

 

[qusp]

very interesting commentary Gary, thanks for your time