Silicon doping
 

HI,

How can I perform doping of silicon manually?

Asad

Asad wrote:
HI,

How can I perform doping of silicon manually?


I'm very skeptical about whether or not
it can be done.


--
\___/
/ O O \
\_____/ FTB. For email, remove my socks.

In science it often happens that scientists say, 'You know
that's a really good argument; my position is mistaken,'
and then they actually change their minds and you never
hear that old view from them again. They really do it.
It doesn't happen as often as it should, because scientists
are human and change is sometimes painful. But it happens
every day. I cannot recall the last time something like
that happened in politics or religion.

- Carl Sagan, 1987 CSICOP keynote address

you do realize that device grade silicon needs to be 99.99999% pure.
Then you normally dope it in a vacuum chamber. It's not something you
can really do by hand.

On Thu, 02 Jun 2005 18:45:58 -0700, Asad wrote:

HI,

How can I perform doping of silicon manually?

Asad

I don't think you can. I'm struggling to remember how it all works. I
think the initial doping is done by the people who make the ingot. Making
an ingot is pretty involved. You would have a very high utility bill if
you decided to make an ingot yourself. But maybe you could buy ingots.

So, let's say it is a P-type ingot. Now you have to create N-type
pockets in order for it to be useful. I think there are two main ways
to do this. (I'm trying to remember. It's all a bit hazy.) I believe
the normal way is that they mask off areas which are to remain P, and
leave the N areas unmasked. Then they heat the wafer and allow N-type
dopant to diffuse in. Like I say, it is all kind of hazy.

There would then be additional rounds of masking and diffusing where you
convert part of your new N-type well back into P-type material (that's
your base). And then there are also metalization steps. Then you would
have to somehow attach leads to the metalized areas. It just seems too
painful, and it's not like would be able to make anything fancier than the
stuff you can buy.

Also, I do remember that nasty chemicals are involved, and the process
control details are critical. Time, temperature, concentration/pressure.
Clean rooms.

--Mac

Asad wrote:
HI,

How can I perform doping of silicon manually?

Asad


sci.skeptic?

On 2 Jun 2005 18:45:58 -0700, "Asad" wrote:

HI,

How can I perform doping of silicon manually?

Asad

Rub Arsenic on the surface with your hand ?:-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"How can I perform doping of silicon manually? "

What dopant do you want to apply? What is the nature of the silicon
substrate? In general, you need a way to apply a closely controlled
concentration of the dopant onto the surface. Arsnic and phosphorus
can be applied as a liquid. Boron is typically applied in a vacuum
either through ion implantation or LPCVD. There are many texts that
explain the theory.

Jim Thompson wrote:
On 2 Jun 2005 18:45:58 -0700, "Asad" wrote:


HI,

How can I perform doping of silicon manually?

Asad


Rub Arsenic on the surface with your hand ?:-)


Wear gloves...arsenic is poison!!!



--
\___/
/ O O \
\_____/ FTB. For email, remove my socks.

In science it often happens that scientists say, 'You know
that's a really good argument; my position is mistaken,'
and then they actually change their minds and you never
hear that old view from them again. They really do it.
It doesn't happen as often as it should, because scientists
are human and change is sometimes painful. But it happens
every day. I cannot recall the last time something like
that happened in politics or religion.

- Carl Sagan, 1987 CSICOP keynote address

On Sat, 04 Jun 2005 01:54:23 +0200, fungus
wrote:

Jim Thompson wrote:
On 2 Jun 2005 18:45:58 -0700, "Asad" wrote:


HI,

How can I perform doping of silicon manually?

Asad


Rub Arsenic on the surface with your hand ?:-)


Wear gloves...arsenic is poison!!!

You missed the smiley ??

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Asad" wrote in message
oups.com...
HI,

How can I perform doping of silicon manually?

Asad


You need either a particle accelerator or an extremely deadly gas (Arsine,
Phosphine or Di-borine depending on you dopant type). Once the dopant is on
the surface of the wafer you will need to activate the dopant with a high
temp furnace (typically a drive-in is done at 950C-1100C). If you used the
particle accelerator you will need to aneal the wafer to restore the smooth
surface. If you only want to dope certain sections of the wafer then you
will need a lithography system. You should be able to pick up used equipment
for about $1million US. Or you can hire a fab to do the work for you.

Also, you will get a better response from sci.engr.semiconductors.

Dwayne