Nanosheet transistor with heterogeneous gate medium and preparation method

Abstract

The invention discloses a nanosheet transistor with a heterogeneous gate medium and a preparation method. The nanosheet transistor comprises a substrate, a source region, a drain region, a gate material and a plurality of nanosheet channel layers; the gate material coats the nanosheet channel layers to form a fence structure; the source region, the fence structure and the drain region are sequentially arranged on the substrate along the channel direction; the channel direction is the direction from the source region to the drain region; heterogeneous gate dielectric layers are arranged between the adjacent surfaces of the gate material and the nanosheet channel layer and between the adjacent surfaces of the gate material and the substrate. Each heterogeneous gate dielectric layer comprises a plurality of gate dielectric materials which are continuously arranged along the channel direction, and the relative dielectric constants of the plurality of gate dielectric materials are gradually reduced along the channel direction; the source region is isolated from the gate region through a first isolation medium; the drain region is isolated from the gate region through the first isolation medium. According to the invention, the short-channel effect of the small-size field effect transistor is reduced, the off-state current leakage is reduced, and the electrical performance of the small-size semiconductor device is improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to a nanosheet transistor with a heterogeneous gate medium and a preparation method thereof. Background technique [0002] As the size of semiconductor devices gradually decreases, the short-channel effect, which has little effect on large-size devices, gradually threatens the performance of small-size devices. The short-channel effect refers to that under the condition of an applied voltage, the depletion region formed at the source-drain PN junction will shorten the channel length in a phase-changing manner. For small-sized devices, the impact of the short-channel effect becomes difficult to ignore. Moreover, due to the shortening of the channel, the electric field intensity at the drain terminal increases, making it easy for carriers to reach the drain terminal through tunneling, resulting in off-state current leakage; this phenomenon seems to reduce the barri...

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Problems solved by technology

[0004] However, even for the nano field effect transistor with the best gate control ability, at a small size, its performance will still be inhibited by the short channel effect due to the high electric field strength at the drain; and if a high dielectric constant material is used as the gate Dielectric to improve the on-state characteristics, the short-channel effect and the current leakage effect in the off-state will be more obvious, which greatly increases the static power consumption of the device

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