RESONATOR
A method of making a resonator, preferably a nano-resonator, includes starting with a FINFET structure with a central bar, first and second electrodes connected to the central bar, and third and fourth electrodes on either side of the central bar and separated from the central bar by gate dielectric. The structure is formed on a buried oxide layer. The gate dielectric and buried oxide layer are then selectively etched away to provide a nano-resonator structure with a resonator element 30, a pair of resonator electrodes ( 32,34 ), a control electrode ( 36 ) and a sensing electrode ( 38 ).
1 . A method of manufacturing a resonator, comprising:
forming a Fin-Field Effect Transistor (FINFET) structure with a substrate, a buried oxide layer on the substrate, a semiconductor layer on the buried oxide layer, the semiconductor layer being patterned to define four semiconductor regions coming together in a central region, the four regions including opposed first and second regions linked by a central bar and opposed third and fourth regions on either side of the central bar, with oxide insulator between each the third and fourth regions and the central bar; and
selectively etching the buried oxide layer and the oxide insulator in the central region to form a cavity under the central bar and to etch away the oxide insulator between the third and fourth regions and the central bar so that the central bar forms a resonator element, the first and second regions form resonator anchors, and the third and fourth regions form control and sensing electrodes.
2 . A method according to claim 1 wherein the step of forming a FINFET structure includes:
forming a first semiconductor layer on the buried oxide layer;
patterning the first semiconductor layer to form the first and second regions and the central bar;
depositing the oxide insulator on the central bar;
depositing a second semiconductor layer; and
patterning the second semiconductor layer to form the third and fourth region on either side of the central region separated from the central bar by the oxide insulator.
3 . A method according to claim 2 , wherein the step of pattering the second semiconductor layer includes carrying out a chemical mechanical polishing step to remove the second semiconductor layer above a predetermined level to remove the second semiconductor layer from above the central bar.
4 . A method according claim 2 wherein the steps of patterning at least one of the first semiconductor layer and the second semiconductor layer include forming a hard mask, patterning the hard mask and then using the hard mask to etch the respective semiconductor layer.
5 . A method of manufacturing a semiconductor device including a resonator, the method comprising:
providing a substrate;
forming a buried oxide layer on the substrate;
forming a resonator on the substrate in a resonator region of the substrate using a method according to claim 1 and forming at least one active device on at least one active device region of the substrate;
depositing and patterning a thermal decomposable polymer over the resonator region;
depositing a permeable dielectric layer over the active device region and over thermal decomposable polymer over the resonator region;
heating the device to decompose the thermal decomposable polymer to form a second cavity.
6 . A method of manufacturing a semiconductor device including a resonator according to claim 5 further comprising, after the step of heating the device to decompose the thermal decomposable polymer, depositing a premetal dielectric over the permeable dielectric layer, and planarising the premetal dielectric by chemical-mechanical polishing.
7 . A method of manufacturing a semiconductor device including a resonator according to claim 6 further comprising forming a multi-layer metallisation over the premetal dielectric.
8 . A method according to claim 5 further comprising etching an opening from the upper surface of the semiconductor device through the permeable dielectric layer to the second cavity to expose the cavity.
9 . A resonator, comprising
a substrate having a first major surface extending longitudinally and laterally;
an insulating layer on the first major surface of the substrate, the insulating layer defining a cavity;
a pair of resonator electrodes longitudinally spaced on the insulating layer on either side of the cavity;
a resonator element linking the resonator electrodes and spanning the cavity;
a control electrode laterally spaced from and on one side of the resonator element;
a sensing electrode laterally spaced from and on the other side of the resonator element from the control electrode;
wherein spacing between the control electrode and the resonator element is less than about 100 nm and the spacing between the sensing electrode and the resonator element is less than about 100 nm.
10 . A semiconductor device, including:
a resonator according to claim 9 on a resonator region of the substrate; and
at least one active device on at least one active device region on the substrate; and
an encapsulant over the resonator region and active device region, the encapsulant defining a cavity, the resonator being in the cavity.
11 . A semiconductor device according to claim 10 , further comprising a multilayer metalisation over the active device region.
12 . A semiconductor device according to claim 10 further comprising an opening through the encapsulant linking the cavity to the outside.