NMOS transistor structure and forming method thereof

Abstract

The invention discloses an NMOS transistor structure and a forming method thereof, which relate to the technical field of basic electronic components. The transistor comprises a substrate, a gate structure, a channel region and a source and drain region. The semiconductor structure further comprises a spherical blocking device, and a carbon-containing material layer located at the interface of thesubstrate and the channel region and at the interface of the substrate and the source and drain region. The spherical blocking device is arranged in the substrate and located below the source and drain region and the channel region. The spherical blocking device is an empty cavity or is filled with an insulating medium. The weight ratio of carbon atoms to silicon atoms in the carbon-containing material layer below the channel region is 1: (0.7-2.4). The leakage current of the semiconductor structure is significantly reduced, and the electrical performance is obviously improved. The method offorming the semiconductor structure has the advantages of simple process, low cost and less impurity introduced, and can further improve the performance of the semiconductor structure.

Description

technical field [0001] The present application relates to the field of semiconductors, in particular to semiconductor structures and methods for forming them, NMOS transistors and methods for forming them. Background technique [0002] In the existing semiconductor structure, as the feature size of MOS devices decreases continuously, the length of the channel becomes shorter, and the width will also be reduced in the same proportion, which will lead to serious short channel effect. This is because when a high voltage is applied to the drain, since the gate is very short, the source is also affected by the electric field of the drain. The depletion region of the junction is connected, so the device cannot be turned off, resulting in a large leakage current. As the channel length is further shortened, the short-channel effect becomes more obvious, which seriously deteriorates the threshold voltage of transistor devices. [0003] In order to solve the above-mentioned technica...

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Problems solved by technology

[0002] In the existing semiconductor structure, with the continuous reduction of the feature size of MOS devices, the length of the channel becomes shorter, and the width will also be reduced in the same proportion, which will lead to serious short channel effect.

This is because when a high voltage is applied to the drain, since the gate is very short, the source is also affected by the electric field of the drain. The depletion region of the junction is connected, so the device cannot be turned off, resulting in a large leakage current

As the channel length is further shortened, the short channel effect is more obvious, which seriously deteriorates the threshold voltage of transistor devices

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