do PNP sit above each other in a wafer?

[PZ]

So in a wafer, in the process of dopant addtion and diffustion, I
understand it is ion implantation to blow a a donor to the vacant
space. Does this apply only to P? how about N type? In reality, for a
transistor, do PNP sit above each other? or in the same planor?


If one sits above another, that means, when blowing ion, there has to
be some kind of strength difference?

 

[Dave Platt]

In article <1137003653.094476.262310@z14g2000cwz.googlegroups.com>,
PZ <patrick.zou@gmail.com> wrote:

So in a wafer, in the process of dopant addtion and diffustion, I
understand it is ion implantation to blow a a donor to the vacant
space. Does this apply only to P? how about N type? In reality, for a
transistor, do PNP sit above each other? or in the same planor?

Either or both. In some transistor designs, the layers are
horizontal. In others, they're vertical / side-by-side. In many,
there's a combination of these two techniques.

As an example - many power MOSFET designs these days are vertical
(VMOSFET) or trench. High power density, low on-resistance and thus
low losses, and thus preferred for high-power switching (motor drive,
switch-mode power supplies, etc.). However, there's still a market
for the older 'lateral' MOSFETs, which seem to find favor in linear
amplification applications such as audio-frequency power amps.

If one sits above another, that means, when blowing ion, there has to
be some kind of strength difference?

Yup. If the ions are implanted via a beam, the energy of the beam
(i.e. the momentum of the ions) controls how deeply they penetrate the
base material before coming to rest.

Ion-beam methods aren't the only ones used for doping. Thermal
diffusion of a gas-transported dopant is another.

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Dave Platt <dplatt@radagast.org> AE6EO
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