Acoustic resonator devices and methods providing patterned functionalization areas
A micro-electrical-mechanical system (MEMS) resonator device includes a top side electrode overlaid with an interface layer including a material having a surface (e.g., gold or other noble metal, or a hydroxylated oxide) that may be functionalized with a functionalization (e.g., specific binding or non-specific binding) material. The interface layer and/or an overlying blocking material layer are precisely patterned to control locations of the interface layer available to receive a self-assembled monolayer (SAM), thereby addressing issues of misalignment and oversizing of a functionalization zone that would arise by relying solely on microarray spotting. Atomic layer deposition may be used for deposition of the interface layer and/or an optional hermeticity layer. Sensors and microfluidic devices incorporating MEMS resonator devices are also provided.
1. A micro-electrical-mechanical system (MEMS) resonator device comprising:
a substrate;
a bulk acoustic wave resonator structure arranged over at least a portion of the substrate, the bulk acoustic wave resonator structure including a piezoelectric material, a top side electrode arranged over a portion of the piezoelectric material, and a bottom side electrode arranged between the piezoelectric material and the substrate, wherein a portion of the piezoelectric material is between the top side electrode and the bottom side electrode to form an active region; an interface layer arranged over at least a portion of the active region, wherein less than an entirety of the piezoelectric material is overlaid with interface layer material that is available to receive a self-assembled monolayer (SAM); and
the self-assembled monolayer arranged over at least a portion of the interface layer.
2. The MEMS resonator device of claim 1 , wherein the interface layer comprises a hydroxylated oxide surface, and the self-assembled monolayer comprises an organosilane material.
3. The MEMS resonator device of claim 1 , wherein the interface layer comprises gold or another noble metal, and the self-assembled monolayer comprises a thiol material.
4. The MEMS resonator device of claim 1 , wherein the interface layer is arranged over less than an entirety of the piezoelectric material.
5. The MEMS resonator device of claim 1 , further comprising a patterned blocking layer arranged over at least one portion of the interface layer.
6. The MEMS resonator device of claim 5 , wherein the patterned blocking layer comprises at least one of silicon nitride, silicon carbide, photoresist, SU-8, polyimide, parylene, or poly (ethylene glycol).
7. The MEMS resonator device of claim 1 , further comprising at least one functionalization material arranged over at least a portion of the self-assembled monolayer, wherein at least a portion of the at least one functionalization material is registered with the active region.
8. The MEMS resonator device of claim 1 , wherein the top side electrode comprises a non-noble metal, and the MEMS resonator device further comprises a hermeticity layer arranged between the interface layer and the top side electrode.
9. The MEMS resonator device of claim 8 , wherein the hermeticity layer comprises an oxide, a nitride, or an oxynitride dielectric material, and the hermeticity layer comprises a water vapor transmission rate of no greater than 0.1 (g/m 2 /day).
10. The MEMS resonator device of claim 1 , wherein the piezoelectric material comprises a hexagonal crystal structure piezoelectric material that comprises a c-axis having an orientation distribution that is predominantly non-parallel to normal of a face of the substrate.
11. A sensor comprising the MEMS resonator device of claim 1 .
12. A fluidic device comprising the MEMS resonator device of claim 7 , and a fluidic passage arranged to conduct a liquid to contact the at least one functionalization material.
13. A method for biological or chemical sensing, the method comprising:
supplying a fluid containing a target species into the fluidic passage of a fluidic device according to claim 12 , wherein said supplying is configured to cause at least some of the target species to bind to the at least one functionalization material;
inducing a bulk acoustic wave in the active region; and
sensing a change in at least one of a frequency property, a magnitude property, or a phase property of the bulk acoustic wave resonator structure to indicate at least one of presence or quantity of target species bound to the at least one functionalization material.
14. A micro-electrical-mechanical system (MEMS) resonator device comprising:
a substrate;
a bulk acoustic wave resonator structure arranged over at least a portion of the substrate, the bulk acoustic wave resonator structure including a piezoelectric material, a top side electrode arranged over a portion of the piezoelectric material, and a bottom side electrode arranged between the piezoelectric material and the substrate, wherein a portion of the piezoelectric material is arranged between the top side electrode and the bottom side electrode to form an active region;
a self-assembled monolayer arranged over at least a portion of the active region; and
at least one functionalization material arranged over at least a portion of the self-assembled monolayer, wherein less than an entirety of the piezoelectric material is overlaid with the at least one functionalization material.
15. A method for fabricating a micro-electrical-mechanical system (MEMS) resonator device, the method comprising:
forming a bulk acoustic wave resonator structure including a piezoelectric material, a top side electrode arranged over a portion of the piezoelectric material, and a bottom side electrode arranged between the piezoelectric material and a substrate, wherein a portion of the piezoelectric material is arranged between the top side electrode and the bottom side electrode to form an active region;
depositing an interface layer over at least a portion of the active region, wherein less than an entirety of the piezoelectric material is overlaid with interface layer material that is available to receive a self-assembled monolayer (SAM); and
forming a self-assembled monolayer over at least a portion of the interface layer, wherein at least a portion of the self-assembled monolayer is arranged over the active region.
16. The method of claim 15 , further comprising applying a patterned mask over at least a portion of the bulk acoustic wave resonator structure prior to the depositing of the interface layer.
17. The method of claim 15 , further comprising depositing at least one functionalization material over at least a portion of the self-assembled monolayer, wherein the at least one functionalization material is registered with at least a portion of the active region.
18. The method of claim 15 , wherein the top side electrode comprises a non-noble metal, and the method further comprises depositing a hermeticity layer between at least portions of the interface layer and the top side electrode, wherein the hermeticity layer comprises an oxide, a nitride, or an oxynitride dielectric material, and wherein the hermeticity layer comprises a water vapor transmission rate of no greater than 0.1 (g×mm)/(m 2 ×day).
19. The method of claim 15 , further comprising depositing a patterned blocking layer over at least one portion of the interface layer.
20. The method of claim 15 , further comprising forming at least one wall over a portion of the bulk acoustic wave resonator structure and defining a fluidic passage containing the active region.