Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2001-06-06
2002-08-13
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S151000, C438S149000
Reexamination Certificate
active
06432777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to semiconductor devices and more particularly to a method of manufacturing semiconductor device that reduces undesirable short-channel effects.
2. Description of the Related Art
The threshold voltage of a metal oxide semiconductor field effect transistor (MOSFET) decreases as the gate length or channel length decreases for “short” gate lengths. This is commonly known as the “short channel effect”. This short channel effect increases the off current of the minimum length MOSFET and is one of the constraining limitations in a MOSFET technology. Therefore, there is a need to reduce the short channel effect. Conventionally, the average well doping is increased as the gate length decreases to counter the short channel effect.
It is common practice to introduce higher well doping near the edge of the gate by an angled implantation after the gate is patterned. This is referred to as a “halo” implant. The halo implant doping is a larger fraction of the well doping for short gate lengths, thus increasing the average well doping for short gate lengths as compared to long gate lengths. A halo implant has limits in its effectiveness due to its limited spatial extent near the edge of the gate (e.g., the halo implant only exists around the edge of the gate conductor, not in the center region below the gate conductor).
The maximum electrically active dopant concentration achievable by halo implantation is limited by the solid solubility of the implanted dopant. Also, the angle at which the halo implant can be implanted is limited by the height and proximity of an adjacent gate structure which could potentially block the angled halo implant.
SUMMARY OF THE INVENTION
The invention includes a method of manufacturing a metal oxide semiconductor field effect transistor (MOSFET). The method forms an insulator layer over a substrate and a doped layer over the insulator layer. Further, the invention patterns a conductor layer over the doped layer. The conductor layer includes gate conductors. The invention implants a second impurity through the conductor layer and into the doped layer. The second impurity is of an opposite type than that of the first type of impurity. Also, the second impurity decreases the concentration of the first impurity in the doped layer. The amount of the second type of impurity that penetrates through the conductor layer into the doped layer changes depending upon the length of the gate conductors within the conductor layer.
The second impurity that penetrates through the conductor layer decreases in concentration as the length of the gate conductors decreases. Also, the decrease in the amount of the second impurity increases the concentration of the first impurity that remains in the doped layer. The invention anneals the MOSFET structure after the implanting process. The doped layer is formed by a deposited doped layer and an undoped layer followed by doping implantation.
REFERENCES:
patent: 4649629 (1987-03-01), Miller et al.
patent: 4737471 (1988-04-01), Shirato et al.
patent: 5091324 (1992-02-01), Hsu et al.
patent: 5166765 (1992-11-01), Lee et al.
patent: 5185279 (1993-02-01), Ushiku
patent: 5329138 (1994-07-01), Mitani et al.
patent: 5527721 (1996-06-01), Farb
patent: 5753958 (1998-05-01), Burr et al.
patent: 5814869 (1998-09-01), Dennen
patent: 5965917 (1999-10-01), Maszara et al.
patent: 5965926 (1999-10-01), Schwalke
patent: 6103580 (2000-08-01), Guo
patent: 6146953 (2000-11-01), Lee et al.
patent: 6291325 (2001-09-01), Hsu
patent: 6313012 (2001-11-01), Horiuchi et al.
patent: 6337505 (2002-01-01), Hwang et al.
patent: 6339244 (2002-01-01), Krivokapic
Rausch Werner
Young Ralph W.
Lindsay Jr. Walter L.
McGinn & Gibb
Niebling John F.
Pepper Margaret A.
LandOfFree
Method for increasing the effective well doping in a MOSFET... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for increasing the effective well doping in a MOSFET..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for increasing the effective well doping in a MOSFET... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2926871