Why lightly doped drains(LDD) are required in MOS fabrication?

[sheraz.pervaiz]

Why lightly doped drains(LDD) are required in MOS fabrication?

 

[icecream]

Re: Lightly doped drains

light-doped region of drain below gate electrode>>
- parasitic capacitance is suppressed
- the intensity of electric field in drain is decreased
- suppressed the probability of formation of hot electrons

heavy doped drain region far away from gate electrode>>
- serial resistance of drain is suppressed

regards

 

[hareeshnaidu]

Lightly doped drains

LDD structures are mainly to reduce the hot electron effects

 

[sabari]

Lightly doped drains

LDD -- (low dopped drain) structures are mainly to reduce the hot electron effects

 

[electronics_kumar]

Lightly doped drains

in BJT also DRAIN's counter part Emiiter is lightly doped

 

[SkyHigh]

Re: Lightly doped drains

hi electronics_kumar,

in BJT also DRAIN's counter part Emiiter is lightly doped

Drain in BJT?


To others, you have only answered with standard answer from textbooks, that is LDD is used to reduce the electric field strength, the gate-drain capacitance and the hot electron impact ionisation effect.

If you are a device engineer, you will know that LDD is only used in NMOS only, not PMOS.
From device engineering view point, LDD reduces the drain-bulk depletion region at the reversed biased junction diode. Therefore LDD reduces leakage current through this diode. This is especially important in advanced nodes at ultra-DSM.

 

[mqc_hn]

Lightly doped drains

If you are a device engineer, you will know that LDD is only used in NMOS only, not PMOS.

Actually N-LDD(for nmos)&P-LDD(for pmos) are default mask steps in any foundry, especially in advanced process.