Structure and method of manufacture for acoustic resonator or filter devices using improved fabrication conditions and perimeter structure modifications
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 bulk acoustic wave device comprising:
a piezoelectric layer overlying a surface of a substrate, the piezoelectric layer having a top piezoelectric surface and a bottom piezoelectric surface;
a top metal electrode on the top piezoelectric surface;
a backside energy confinement structure on the bottom piezoelectric surface, the backside energy confinement structure defined by a backside structure geometric area and a backside structure perimeter;
a backside metal electrode on the bottom piezoelectric surface opposite the top metal electrode wherein the backside structure perimeter of the backside energy confinement structure is outside a perimeter of the backside metal electrode; and
a resonator cavity in the substrate exposing the backside metal electrode.
2. A bulk acoustic wave device comprising:
a piezoelectric layer overlying a surface of a substrate, the piezoelectric layer having a top piezoelectric surface and a bottom piezoelectric surface;
a top metal electrode on the top piezoelectric surface;
a backside energy confinement structure on the bottom piezoelectric surface, the backside energy confinement structure defined by a backside structure geometric area and a backside structure perimeter; and
a backside metal electrode underlying the bottom piezoelectric surface opposite the top metal electrode wherein the backside structure perimeter of the backside energy confinement structure is outside a perimeter of the backside metal electrode.
3. A bulk acoustic wave device comprising:
a piezoelectric layer having a top piezoelectric surface and a bottom piezoelectric surface;
a topside groove in the top piezoelectric surface;
a topside metal electrode on the top piezoelectric surface extending into the topside groove, the topside metal electrode having a topside metal electrode edge and having a topside electrode edge geometric shape;
a backside metal electrode, the backside metal electrode including a backside metal electrode edge having a backside electrode edge geometric shape; and
a backside energy confinement structure on the bottom piezoelectric surface.
4. The bulk acoustic wave device of claim 3 wherein the topside metal electrode includes a first stepped sidewall that conforms to a first edge of the topside groove in the top piezoelectric surface.
5. The bulk acoustic wave device of claim 4 wherein the topside metal electrode extends across topside groove to the topside metal electrode edge opposite in the topside groove opposite the first edge of the topside groove to define a gap located between the topside metal electrode edge and a second stepped sidewall of the topside groove that is opposite the first stepped sidewall.
6. The bulk acoustic wave device of claim 5 wherein the gap exposes a portion of the top piezoelectric surface.
7. The bulk acoustic wave device of claim 5 wherein the gap exposes a portion of the bottom piezoelectric surface.
8. The bulk acoustic wave device of claim 3 further comprising:
a backside groove in the bottom piezoelectric surface, wherein the backside metal electrode extends into the backside groove.
9. The bulk acoustic wave device of claim 8 wherein the backside metal electrode includes a first stepped sidewall that conforms to a first edge of the backside groove.
10. The bulk acoustic wave device of claim 9 wherein the backside metal electrode extends across backside groove to the backside metal electrode edge in the backside groove opposite the first edge of the backside groove to define a gap located between the backside metal electrode edge and a second stepped sidewall of the backside groove that is opposite the first stepped sidewall.