question on native transistor

[mohdfaaf]

native nmos

I read in one of IC processing company (1) official website about their CMOS transistor characteristics. One of the devices they have is native transistor, besides nmos and pmos.
My question is what is native transistor?

One article in website (2) describes native transistor is transistor which lies directly in the substrate. But it doesnt make sense since if the transistor is build in p sub ( which almost all CMOS is build ) , therefore it will be nmos. I believe the description given in the website (1) is referring to a different type transistor other than nmos and pmos.

Please advise.

 

[Hughes]

native transistor

Native mos if formed directly in the substrate. Although it may be nmos, but it has different characteristic with normal nmos. The threshold voltage is very low, and sometimes will be negative. Lack of channel doping makes the native mos have better noise characterisic than normal nmos and pmos.

 

[mohdfaaf]

native mos

Is the different characteristic you mentioned on native transistor due to different design/layout or its just purely due to difference in channel or S/D dopant concentration?

If the Vt is too low or negative for nmos native transistor would it be like depletion type nmos? not enhancement?

It would be helpful if anyone can give me any url/ files that have the details on this.

Thanks.

 

[djalli]

use of native transistors

mohdfaaf it is combination of both: difference in channel & dopining.

 

[mohdfaaf]

native device cmos

any materials or layout to show how this native transistor looks like> ?
I tried to look into websites but failed to find any.

 

[mohdfaaf]

native transistors

to all.

Finally found the definition of native transistor.

"A transistor that has not undergone the channel doping process is termed a "native transistor" and has a lower threshold voltage because it must rely on the intrinsic background or body of the transistor to set the threshold voltage. The typical native transistor threshold voltage can range from 0.1V to 0.3V"
quote from patent description on charge pump

 

[Freakwency]

cmos native device

Hi there, I came here to search for "native mos" and found this thread.
Foundries provide these low-threshold devices but I am wondering what they can do( better than conventional NMOS and PMOS devices.) Is it low-voltage operation?
One poosible application I think about is using them as capacitors since the conventional ones need to be biased in the strong inversion region or the accumulation region but the native transistors don't.

 

[sinbeloanthi]

what are native transistor

NATIVE TRANSISTOR is a transistor formed in a doped semiconductor region, the channel of which has not undergone any surface depletion (P type doping for a PMOS transistor) or surface enhancement (N type doping for a PMOS transistor). The channel is therefore formed directly on the surface of the doped region without the performance of an ion implantation or diffusion after the formation of the well. In the present case, the native transistor is a P type transistor and it is generally formed in an N type well diffused in a P type substrate. The use of such a native transistor in the arm that defines the voltage Vref2, in combination with the use of a resistive divider bridge in the arm that defines Vref1, leads to high stability of the threshold value Vs of supply voltage Vcc that is to be detected. One of the reasons for this stability is the fact that the absence of doping of the channel eliminates a factor of variation of characteristics in the manufacturing method. Furthermore, the use of a resistive divider bridge, alone or complemented by a non-linear element, enables the very efficient control, by a simple choice of relative values of resistance, of the zone of intersection of the curves of Vref1 and Vref2 as a function of Vcc.

 

[mary96960]

native tr

The native NMOS is directly built in a lightly-doped
p-type substrate, whereas the normal NMOS (PMOS) is in a
heavily-doped p-well (n-well) in a P-substrate twin-well
CMOS technology, as shown in Fig. 1. The native NMOS is
fully process-compatible with the standard CMOS process
without adding extra mask. The threshold voltage of native
NMOS is almost zero (-O,lV), however, that of normal
NMOS is about 0.34 V in a 0.13-pm CMOS process.
quote from paper dealing with SCR

 

[montu.gaurav]

what is native mos devices

Hi,

I was looking for Native NMOS and I reached this thread. Can any one explain me the reason of low VT for the native NMOS transistors? If a transistor is being made in p-well then it will be NMOS thts ok with me. Is the reason for very low VT is very lightly doped p type substrate?

 

[soheil_radiom]

native nmos transistor

Could you please explain for me more about the native transistors?
I would like to know if I can use them in rectifiers with RFID applications where they should be diode connected. There, we need low Vth transistors since the input voltage range is not that much and it helps us to bias the transistors in Saturation instead of Subthreshold.
But I am wondering what is the disadvantage of using them? How will be the leakage current behavior there?

Thanks in advance.

 

[sandeep_torgal]

what is different in native mos transistors

Native mos if formed directly in the substrate. Although it may be nmos, but it has different characteristic with normal nmos. The threshold voltage is very low, and sometimes will be negative. Lack of channel doping makes the native mos have better noise characterisic than normal nmos and pmos.

Can anybody throw more light on this...

 

[timof]

native devices cmos

Intrinsic transistors are more prone to source-drain leakage due to lower doped channel (short channel effect, DIBL).

In CMOS image sensors, intrinsic transistors are used for transfer gates to
transfer photo-generated charge from the photodiode to the sense node (floating diffusion) - having lower doping in the channel leads to lower potential barrier for electron transfer from photodiode to sense node, and helps to avoid lag effect (incomplete transfer of photogenerated charge and resulting memory effect).

 

[tzg6sa]

Re: what is different in native mos transistors

Native mos if formed directly in the substrate. Although it may be nmos, but it has different characteristic with normal nmos. The threshold voltage is very low, and sometimes will be negative. Lack of channel doping makes the native mos have better noise characterisic than normal nmos and pmos.

Can anybody throw more light on this...

A possible explanation:
Since it is not doped, there are not so many charge traps in the substrate. In that case the flicker noise would be less, but it should not affect the thermal noise.

But I am not a technology expert.

 

[arnabbiswas_ece]

i am wondering how a topic is alive so long because it generated in 2004.and now it is 2010.

 

[tdf]

Hi all,

For a certain process, the threshold voltage will increase as follows: native NMOS, low-Vt NMOS, normal NMOS and high-Vt NMOS. Is that right? Can anyone confirm?

How about the alternative native NMOS?

Thanks,

TDF