P-type, N-type silicon wafer

[Newbies_Kid]

Can somebody tell me what the differences between P-type & N-type Si Wafer?? If i want to use it as a substrate to be coated with a metallic coating, which one should i preferred to choose? and why?. Thanks

[Klaynos]

It depends on which carrier concentration is increased by the doping.

 

What do you want to do with the coated substrate and how are you intending to coat it? What metal are you going to use?

[alpha2cen]

Can somebody tell me what the differences between P-type & N-type Si Wafer?? If i want to use it as a substrate to be coated with a metallic coating, which one should i preferred to choose? and why?. Thanks

 

Before making a chip, you need to simulate the chip making procedure and the chip electronic property by using commercial software. During that simulation the software tells you which wafers are suitable for making your chip.

[Newbies_Kid]

actually i didn't intended to make a chip or something from those Si wafer, currently i'm studying nanoscale thin film and i just want to use the Si-wafer as a test material before i do my real coating on Alumina substrate. The price for alumina is far more expensive and i'm afraid it will be wasted if the chosen sputtering parameters were wrong.So, I will coat using RF Magnetron sputtering and the target's material will be Ti-Al-Cu, and prior to the real coating, all parameters will be tested on Si-wafer first. I chose Si-wafer because it acquired single crystal structure as alumina had. But i'm getting confuse here when the supplier ask me for which one, N-type or P-type?? What are their differences based on structural kinetic and thermal properties? If you had any experience on Si-wafer deposition, which one can result good thin film? I search in most material's info website but nothing could help me so far

[Klaynos]

I've done quite a lot of evaporating metals onto Si, which isn't the same as sputtering.

 

So doping is adding another material to the Si, but in a quite low concentration.

 

Depending on how important the single crystal structure is to you I don't think it'll make that much difference the doping concentration is generally very low.

 

But if you want to be confident just buy undopped wafers, people like university wafer supply them.

 

You will nearly definitely get a bigger difference in results from your two different substrates than from between two differently dopped Si wafers in terms of smoothness, and adhesion strength. As for thermal properties, there is a useful graph here:

 

http://www.ioffe.ru/SVA/NSM/Semicond/Si/thermal.html

 

Which also has a decent reference, but note "For T > 100 K thermal conductivity is practically independent of N." So as long as you're at room temperature it's not going to make much difference.

[Newbies_Kid]

"Undopped wafers" thanks for the keyword! Seriously i never used to know about these material before because my background is mechanical engineering. I found the price of undopped wafers in University wafer but i'm wonder why the price for the undopped wafer is much higher than the dopped one?? For example, 15 wafers p-type Si:B [100] 4" 2,300micron thick is sold at $59.00 while a 100mm Intrinsic (100) 380um >20,000 ohm-cm SSP Prime one wafer sold for $150.00 each.. that's was so expensive just like the alumina...nevertheless i will try to ask our local supplier first. Secondly, there are one more type of Si-wafer which attract my attention, the SOI. I don't know how the oxide box are chemically bonded to the substrate and the thin Si film but i'm thinking if i grind out the thin si layer on the top, will the exposed oxide layer could stay unaffected and may not oxidized?

[Mr Skeptic]

I found the price of undopped wafers in University wafer but i'm wonder why the price for the undopped wafer is much higher than the dopped one??

 

My guess is that it is probably purer, and almost certainly far less used (so suffers from a lack of economies of scale).

[alimeeabey]

The electrical properties of silicon can be changed or manipulated by adding up the other elements called “dopants” which determine the type of silicon wafer. Either negative or positive, and these dopants also modify the resistivity of silicon to make it more conductive.

Therefore, we can say that the type of “dopant” added determines the final wafer. Whether it’s an N-Type or a P-Type silicon wafer. And the amount of dopant determines wafer’s final resistivity.

P-Type silicon wafers are very common in terms of production and sales volume. These types of wafers are formed with only one type of dopant called boron. Amount of boron in the silicon wafer determines its resistivity; the less boron the more will be the resistivity while the more boron the lower resistivity.

Visit here for more information - https://en.wikipedia.org/wiki/Extrinsic_semiconductor#N-type_semiconductors

http://www.wafernet.com/p-type-silicon-wafers.htm

[Enthalpy]

N or P makes no difference to sputter metal on it. Same conductivity, same crystal quality. Pick any.

 

If useful to measure your metal film, you can deposit or grow an insulating layer on the silicon.

 

As-grown silicon boule contains a little bit of boron from the BN melting pot. It was like 10^-12cm^-3 when I was in the business, during the paleomonolithic era. This is too much to be "intrinsic", for instance to deplete a 300µm thick wafer under a convenient voltage for a sensor (or even, the voltage may exceed breakdown). Since it's a minimum boron concentration, other tricks are needed to get the bulk free of carriers:

- Introduce a dopant with deep levels, which stabilizes the Fermi level around mid-gap

- Or grow more semiconductor by epitaxy. The quality improves there, it's generally done for chips (where it also allows a small doping over a strong one), but not over 300µm new thickness!