Method for fabricating an acoustic resonator device
A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.
1. A method for fabricating an acoustic resonator device, the method comprising:
forming a piezoelectric film overlying a growth substrate, the piezoelectric film having a top piezoelectric surface region and a bottom piezoelectric surface region;
forming a first electrode overlying the piezoelectric film, the first electrode having one or more first electrode edges being characterized by a first electrode edge geometric shape;
forming a first passivation layer overlying the first electrode and the piezoelectric film;
forming a sacrificial layer overlying the first passivation layer, the first electrode, and the piezoelectric film;
forming a support layer overlying the sacrificial layer, the first passivation layer, the first electrode, and the piezoelectric film thereby forming a device on the growth substrate;
polishing the support layer;
forming a bonding support layer overlying a bond substrate;
flipping the device on the growth substrate and bonding the polished support layer to the bonding support layer thereby forming a bonded device;
removing the growth substrate from the bonded device;
forming an electrode contact via within the piezoelectric film overlying the first electrode on the bonded device;
forming one or more release holes within the piezoelectric film and the first passivation layer overlying the sacrificial layer on the bonded device;
forming a second electrode layer overlying the piezoelectric film and within the contact via;
etching the second electrode layer to form a top metal separated from a second electrode, wherein the top metal is physically coupled to the first electrode through the electrode contact via and the second electrode is overlying the piezoelectric film, the second electrode having one or more second metal electrode edges being characterized by a second electrode edge geometric shape;
forming a first contact metal overlying the second electrode and the piezoelectric film;
forming a second contact metal overlying the top metal and the piezoelectric film;
forming a second passivation layer overlying the piezoelectric film, the second electrode, and the top metal; and
removing the sacrificial layer by way of the one or more release holes to form an air cavity within the bonded device.
2. The method of claim 1 wherein forming the first electrode and the second electrode includes an edge profile fabrication process to form the one or more first electrode edges and the one or more second electrode edges, wherein the edge profile fabrication process can be selected from the following: a patterned sputtering process, a patterned evaporation and lift-off process, an evaporation and patterned etching process, a trimming process, a laser ablation process, and an ion beam milling process.
3. The method of claim 1 wherein the second electrode edge geometric shape includes one of the following shapes: a down slope edge, an up slope edge, an up and down slope edge, an up-flat-down slope edge, a stair steps edge, and a circular edge.
4. The method of claim 1 wherein the second electrode includes a groove formed within the second electrode within a vicinity of the one or more second electrode edges.
5. The method of claim 1 wherein the first electrode edge geometric shape includes one of the following shapes: a down slope edge, an up slope edge, an up and down slope edge, an up-flat-down slope edge, a stair steps edge, and a circular edge.
6. The method of claim 1 wherein the first electrode includes a groove formed within the first metal electrode within a vicinity of the one or more first electrode edges.
7. The method of claim 6 wherein forming the first electrode includes forming the first electrode such that first electrode edge geometric shape is spatially configured within or below the bottom piezoelectric surface region.
8. The method of claim 1 wherein each of the first electrode edge geometric shape and the second electrode edge shape includes one of the following shapes: a down slope edge, an up slope edge, an up and down slope edge, an up-flat-down slope edge, a stair steps edge, and a circular edge;
wherein the first electrode includes a groove formed within the first electrode within a vicinity of the one or more first electrode edges; and
wherein the second electrode includes a groove formed within the second electrode within a vicinity of the one or more second electrode edges.
9. The method of claim 1 further comprising removing a portion of the piezoelectric film to form a first topside groove on the top piezoelectric surface region, wherein the first topside groove is spatially configured overlying the air cavity.
10. The method of claim 9 further comprising removing a portion of the piezoelectric film to form a second topside groove on the top piezoelectric surface region; wherein the second topside groove is spatially configured within the vicinity of an edge of the second electrode and the first topside groove.
11. The method of claim 10 wherein the first topside groove is spatially configured overlying a portion of the air cavity and the second topside groove is spatially configured overlying a portion of the substrate.
12. The method of claim 1 further removing a portion of the piezoelectric film to form a first backside groove on the bottom piezoelectric surface region, wherein the first backside groove is spatially configured within the air cavity.
13. The method of claim 12 further comprising removing a portion of the piezoelectric film to form a second backside groove on the bottom piezoelectric surface region; wherein the second topside groove is spatially configured within the vicinity of an edge of the second electrode and the first backside groove.
14. The method of claim 13 wherein the first backside groove is spatially configured within a portion of the air cavity and the second topside groove is spatially configured within a portion of the air cavity.
15. The method of claim 1 further comprising forming a topside edge border material overlying and physically coupled to a portion of the top piezoelectric surface region and physically coupled to a portion of the topside metal electrode.
16. The method of claim 15 wherein the topside edge border material includes a metal material or a dielectric material.
17. The method of claim 15 wherein forming the topside edge border material includes forming the topside edge border material overlying a portion of the second electrode.
18. The method of claim 15 further comprising removing a portion of the second electrode within a vicinity of the topside edge border material to form a topside electrode groove.
19. The method of claim 1 further comprising forming a backside edge border material underlying and physically coupled to a portion of the bottom piezoelectric surface region and physically coupled to a portion of the backside metal electrode.
20. The method of claim 19 wherein the backside edge border material includes a metal material or a dielectric material.
21. The method of claim 19 wherein forming the backside edge border material includes forming the backside edge border material overlying a portion of the first electrode.
22. The method of claim 19 further comprising removing a portion of the first electrode within a vicinity of the backside edge border material to form a backside electrode groove.