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PMOS Tuning

PMOS devices are a special case since the boron doped Source/Drain implants overall tend to absorb interstitials rather than emit them. The reverse short channel effect in buried channel PMOS devices can be caused by high angle implants. If high angle implants are used, the reverse short channel effect can be tuned using the LAT.RATIO1 parameter in the IMPLANT statement.

7.8.5: Related Issues on using the Device Simulator ATLAS for MOS Process Tuning

It should now be known that calibrating an ATHENA process file involves using the device simulator ATLAS to a significant extent. Hence, it’s imperative that the use of the device simulator doesn’t create additional errors, rendering the process calibration results invalid.

Fortunately, the device physics involved in simulating the conditions required to extract a threshold voltage are not demanding. The drain voltage required to extract a threshold voltage is only 50-100mV so effects such as impact ionization can be neglected. The field perpendicular to the gate is also relatively low around the threshold voltage so field effects in this direction will do little effect. We recommend, however, using at least the models SRH and CVT during the calculation. Other parameters for silicon are sufficiently well known for silicon to the point that the results from the device simulator are reliable.

The first important point is to ensure that you let the device simulator calculate the work function of the gate electrode from the simulated doping profile rather than assigning a value to it. This means, making sure that the polysilicon gate is not itself defined as an electrode but rather a layer of metal, usually aluminum, is deposited on top of the polysilicon gate. Therefore, this metal layer is the film defined as the electrode. Do not assign a work function to this deposited metal electrode to ensure that it behaves as an ohmic contact rather than a Schottky contact. The effective work function of the poly gate will then be correctly calculated from the doping profile in the polysilicon.

An important area for accuracy in MOSFETs is modeling the inversion region under the gate. As it is, this charge that is responsible for current conduction in the device. The inversion region charge under the gate-only extends approximately 30 Angstroms into the silicon. The inversion region charge density under the gate falls off rapidly with depth into the silicon. It is imperative that there are several mesh points in the Y direction in this inversion region to model the drain current correctly. Accordingly, we recommend that the mesh spacing under the gate be no more than 10 Angstroms (1 nm).

You would think that a 10 Angstrom mesh under the gate would result in a huge number of mesh points. But, there only needs to be approximately three mesh points within the inversion region in the Y direction. The grid spacing can increase rapidly in spacing away from the oxide-silicon interface.

Figure 7.43 shows the effects of changing the mesh spacing at the interface on the simulated drain current. You can see from this figure that too coarse of a mesh always results in too high of a current simulated.

Figure 7.43: The effect of changing the mesh spacing at the interface on the simulated drain current

If contact resistance is a problem, then include it in the CONTACT statement. The resistance added to the CONTACT statement should be the measured resistance per contact divided by the number of contacts on each individual electrode. Obviously for D.C. measurements, the resistance on the gate contact will have no effect on the results since no current flows in this direction.

Checking the Predictive Powers of Tuned Process Parameters

If the process simulation has been correctly tuned, the process and device simulators should have predictive powers. To check the validity of the tuning process, use a new set of electrical data that was not used during the tuning process. For example, a good alternative set of data is to check the threshold voltage versus gate length for a non-zero voltage applied to the MOSFET body contact.


Using just one set of easily obtained measured electrical data, namely a plot of threshold voltage versus gate length, you can obtain most of the tuning parameters required for accurate process simulation. The other most important piece of data required is an accurate measurement of the gate oxide thickness, which is routinely measured in any instance.

You have been given specific advice as to which process and device models to use for each process in order to get the best results out of the simulation software. In particular, the correct use of models for the implantation and diffusion processes is stressed, as this has a dramatic effect on MOSFET characteristics, especially as anneal times and device dimensions decrease.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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