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The Resonant Body Transistor and Oscillator

Detailed Technology Description

A novel resonant body transistor (RBT) comprising a bulk-mode resonator with side-wall dielectric for capacitive drive and gate oxide sensing which is easier to fabricate and operates better than existing RBTs has been developed.

Others

• Patent:  8,624,337
• Patent application:  200880126205.7
• Weinstein, Dana, Bhave, Sunil A. (2007, December 10-12). Internal dielectric transduction of a 4.5 GHz silicon bar resonator. IEEE International Electron Devices Meeting (IEDM 2007), Washington, DC, 415-418.
• Weinstein, Dana, Sunil, Bhave A. (2008, June 1-5). Piezoresistive sensing of a dielectrically actuated silicon bar resonator. Solid State Sensor, Actuator and Microsystems Workshop, Hilton Head Island, South Carolina, 368-371.  

*Abstract

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The novel nano-electromechanical system (NEMS) device functions as a building block in deep, sub-micron (DSM) CMOS applications. The RBT consists of an internal dielectric bulk acoustic resonator embedded with a transistor in the resonant body (see figure 1).

 

 

Acoustic resonance is first excited in the device with a harmonic force (AC voltage) at the transistor gate(s). At resonance, the transconductance of the transistor is enhanced due to (1) the harmonic change in gate oxide thickness, (2) piezoresistive effects, and (3) strain-induced mobility enhancement of the charge carriers in the inverted region of the device. This novel method of electromechanical transduction bypasses the obstacle of large feed-through capacitance and improves motional impedance relative to traditional capacitively-transduced acoustic resonators.

 

The RBT enables sensing of resonant excitation at frequencies above 10 GHz. Furthermore, by closing the feedback loop on the RBT, one can form a resonant body oscillator (RBO). With a footprint of < 1m², the RBO provides a compact, low-power solution to on-chip local clock distribution.

 

Figure 2 shows a schematic of a simple Piece crystal oscillator. Each of the four components in the oscillator generates a 90 degree phase shift while the transistor provides the gain necessary to close the feedback loop. The crystal and transistor of the Piece oscillator can be replaced by a single RBT, which can be engeneered to incorporate shunt capacitors. The entire Piece crystal oscillator can therefore be formaed from a single Resonant Body Transistor, as shown in figure 3.

                                     

Potential Applications

• Resonant Body Oscillator (RBO) can serve as a low-power, compact internal resonator for chips to replace global clocks for generating the synchronizing signal with a local clock.
• Resonant Body Transistor (RBT) - in addition to forming a key component of the RBO, can be used to make a FinFet, a very compact transistor that is of great interest to chip-makers due to compactness.

                                                      

Advantages

• Easy to fabricate
• Improved performance over existing RBTs
• RBO is compact, low-power, compatible with CMOS

*Licensing

Patrick Govangpjg26@cornell.edu(607) 254-2330

Country/Region

USA