Globalfoundries Inc.

Globalfoundries U.S. Inc.

Srikanth Srihari

Anthony K Stamper

Steven M Shank

Uzma B Rana

Venkata N R Vanukuru

A transistor includes a bulk semiconductor substrate, and a first source/drain region in the bulk semiconductor substrate separated from a second source/drain region in the bulk semiconductor substrate by a channel region. A first air gap is defined in the bulk semiconductor substrate under the first source/drain region, and a second air gap is defined in the bulk semiconductor substrate under the second source/drain region. A gate is over the channel region. A spacing between the first air gap and the second air gap is greater than or equal to a length of the channel region such that the first and second air gaps are not under the channel region. The air gaps may have a rectangular cross-sectional shape. The air gaps reduce off capacitance of the bulk semiconductor structure to near semiconductor-on-insulator levels without the disadvantages of an air gap under the channel region.

Transistor with air gap under source/drain region in bulk semiconductor substrate

An SPDT switch in a RF communication transceiver provides for choosing the transmit/receive path for the RF signal. It consists of the series and shunt branches each consisting of stack of FETs. Performance metrics of the RF switch are insertion loss and isolation. At high frequency, the device/FET capacitance and the parasitic capacitances provide a leakage path for the signal, resulting in higher insertion loss and lower isolation. A parallel resonant LC network across each of the series and/or shunt branch FETs in a SPDT switch provides lower insertion loss, higher switch isolation, and lower out of band harmonics when compared to that of the state of the art SPDT switch. A method to reduce the form factor of such switch configuration is disclosed which is useful in wireless front end modules.

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Bengaluru, India

Srikanth Srihari