What is self-aligned gate process?

From Wikipedia, the free encyclopedia. In electronics, a self-aligned gate is a transistor manufacturing feature whereby a refractory gate electrode region of a MOSFET (metal–oxide–semiconductor field-effect transistor) is used as a mask for the doping of the source and drain regions.

Why polysilicon is used in CMOS?

Undoped polysilicon has very high resistivity, approximately 108 ohm/Cm. So, polysilicon is doped in such a way that its resistance is reduced. The other reason for selecting polysilicon is that the threshold voltage of MOS transistor is correlated with the work function difference between the gate and the channel.

Why polysilicon is used for gate in MOSFET?

Thus, poly-crystalline silicon (polysilicon) became the modern gate material because it is the same chemical composition as the silicon channel beneath the gate oxide. In inversion, the work-function difference is close to zero, making the threshold voltage lower and ensuring the transistor can be turned on.

What is the difference between metal gate and polysilicon gate technology?

One major difference is between transistors with a metal gate and transistors with a polysilicon gate. When a polysilicon gate is used, polysilicon is deposited before the gate is defined. The source and drain regions are then doped while keeping the channel doping at a different type.

What is MOS silicon gate technology?

The Silicon Gate Technology was the world’s first commercial MOS self-aligned-gate process technology. Before this technology, the control gate of the MOS transistor was made with aluminum instead of polycrystalline silicon. In 1968, almost all the integrated circuits sold used bipolar transistors.

What is pMOS transistor?

A p-channel metal-oxide semiconductor (pMOS) transistor is one in which p-type dopants are used in the gate region (the “channel”). A negative voltage on the gate turns the device on.

Why is polysilicon used?

– polysilicon is used as semimetal layer for conveying signals. and so one can add an additional layer of the integrated circuit to increase the interconnects and the transistor density. – One can use them for self aligning the source and drain where one defines the gate, the source and drain simultaneously.

What is polysilicon used for?

Polysilicon is a hyper pure form of silicon and is the earth’s second most abundant element. Due to its semiconductor-like material properties, polysilicon is used as feedstock material in most solar energy applications. Polysilicon is an initial building block for the process of manufacturing silicon based Solar PV.

What is the main use of polysilicon in designing?

Polysilicon is used both as gate electrode material for MOS transistors and also as an interconnect medium in silicon integrated circuits. Undoped polysilicon has relatively high resistivity. The resistivity of polysilicon can be reduced, however, by doping it with impurity atoms.

What is the difference between silicon and polysilicon?

In context|chemistry|lang=en terms the difference between silicon and polysilicon. is that silicon is (chemistry) a nonmetallic element (symbol si) with an atomic number of 14 and atomic weight of 280855 while polysilicon is (chemistry) containing many silicon atoms, especially when linked into chains or networks.

What is NMOS PMOS and CMOS?

CMOS and NMOS are two logic families, where CMOS uses both MOS transistors and PMOS for design and NMOS use only field-effect transistors for design. CMOS is selected over NMOS for the designing of an embedded system.