Air gap over transistor gate and related method

Abstract

The invention relates to an air gap over transistor gate and a related method. A semiconductor device may include a transistor gate in a device layer; an interconnect layer over the device layer; and an air gap extending through the interconnect layer to contact an upper surface of the transistor gate. The air gap provides a mechanism to reduce both on-resistance and off-capacitance for applications using SOI substrates such as radio frequency switches.

Description

technical field [0001] The present invention relates to semiconductor devices, and more particularly to an air gap over a gate of a transistor and a method for forming the same. This air gap reduces the off-state capacitance (C off ). Background technique [0002] Radio frequency (radio frequency; RF) switches are widely used in telecommunication devices such as smartphones to route high frequency telecommunication signals through transmission paths. For example, RF switches are commonly used in smartphones to allow the use of different digital wireless technology standards in different terrains. Current RF switches are typically fabricated using semiconductor-on-insulator (SOI) substrates. Typically, SOI substrates use layered silicon-insulator-silicon substrates instead of more traditional silicon substrates (bulk substrates). SOI-based devices differ from conventional silicon-built devices in that the silicon junction sits on top of an electrical insulator, typically ...

AI Technical Summary

Problems solved by technology

[0003] One challenge in forming RF switches in SOI substrates is controlling two conflicting parameters: the on-resistance (R on ), the resistance of the switch when the power is on; and the off-state capacitance (C off ), which represents the amount of crosstalk or noise that may occur within the system, that is, the amount by which a signal transmitted on one circuit adversely affects another circuit

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