Acoustic wave filter formed on a V-groove topography and method for producing the same
Methods of forming a shear-mode acoustic wave filter on V-shaped grooves of a [100] crystal orientation Si layer over a substrate and the resulting devices are provided. Embodiments include forming a set of V-shaped grooves in a [100] crystal orientation Si layer over a substrate; and forming a shear-mode acoustic wave filter over the V-shaped grooves, the shear-mode acoustic wave filter including a first metal layer, a thin-film piezoelectric layer, and a second metal layer, wherein the second metal layer is an IDT pattern or a sheet.
1. A method comprising:
forming a set of V-shaped grooves in a [100] crystal orientation silicon (Si) layer over a substrate; and
forming a shear-mode acoustic wave filter over the V-shaped grooves, the shear-mode acoustic wave filter comprising a first metal layer, a thin-film piezoelectric layer, and a second metal layer,
wherein the second metal layer comprises an interdigitated (IDT) pattern or a sheet.
2. The method according to claim 1 , further comprising:
forming pairs of vias through the thin-film piezoelectric layer and the first metal layer and optionally through the second metal layer, the thin-film piezoelectric layer, and the first metal layer down to the [100] crystal orientation Si layer subsequent to the forming of the shear-mode acoustic wave filter, each via of each of the pairs of vias formed on an opposite side of the set of V-shaped grooves; and
forming a cavity in the [100] crystal orientation Si layer under the first metal layer, the cavity extending beyond the set of V-shaped grooves,
wherein the pairs of vias are formed through second metal layer when the second metal layer is the sheet.
3. The method according to claim 2 , comprising forming each opposing slope of the V-shaped grooves with an angle of 54.7 degrees by a wet etch or with an angle between 10 degrees and 70 degrees by a dry etch.
4. The method according to claim 2 , wherein the IDT pattern has a same or a different lateral width across the set of V-shaped grooves.
5. The method according to claim 2 , wherein the V-shaped grooves are formed by a wet etch and the second metal layer is the sheet, the method comprising forming the V-shaped grooves with a flat bottom.
6. The method according to claim 1 , further comprising:
forming a Bragg reflector along the V-shaped grooves prior to the forming of the shear-mode acoustic wave filter; and
forming the shear-mode acoustic wave filter over the Bragg reflector.
7. The method according to claim 6 , further comprising:
forming pairs of vias through the thin-film piezoelectric layer and the first metal layer and optionally through the second metal layer, the thin-film piezoelectric layer, and the first metal layer down to the [100] crystal orientation Si layer subsequent to the forming of the shear-mode acoustic wave filter, each via of each of the pairs of vias formed on an opposite side of the set of V-shaped grooves; and
forming a cavity in the [100] crystal orientation Si layer under the Bragg reflector, the cavity extending beyond the set of V-shaped grooves,
wherein the pairs of vias are formed through second metal layer when the second metal layer is the sheet.
8. The method according to claim 7 , comprising forming each opposing slope of the V-shaped grooves with an angle of 54.7 degrees by a wet etch or with an angle between 10 degrees and 70 degrees by a dry etch.
9. A device comprising:
a set of V-shaped grooves in a [100] crystal orientation silicon (Si) layer over a substrate; and
a shear-mode acoustic wave filter over the V-shaped grooves, the shear-mode acoustic wave filter comprising a first metal layer, a thin-film piezoelectric layer, and a second metal layer,
wherein the second metal layer comprises an interdigitated (IDT) pattern or a sheet.
10. The device according to claim 9 , further comprising: pairs of vias through the thin-film piezoelectric layer and the first metal layer and optionally through the second metal layer, the thin-film piezoelectric layer, and the first metal layer down to the [100] crystal orientation Si layer, each via of each of the pairs of vias formed on an opposite side of the set of V-shaped grooves; and
a cavity in the [100] crystal orientation Si layer under the first metal layer, the cavity extending beyond the set of V-shaped grooves,
wherein the pairs of vias are formed through second metal layer when the second metal layer is the sheet.
11. The device according to claim 10 , wherein each opposing slope of the V-shaped grooves has an angle of 54.7 degrees or an angle between 10 degrees and 70 degrees.
12. The device according to claim 10 , wherein the IDT pattern has a same or a different lateral width across the set of V-shaped grooves.
13. The device according to claim 10 , wherein the set of V-shaped grooves comprises a row or a column of 10 V-shaped grooves, 10 rows or 10 columns of the 10 V-shaped grooves, or a plurality of V-shaped grooves.
14. The device according to claim 10 , wherein the second metal layer is the sheet, the V-shaped grooves have a flat bottom.
15. The device according to claim 9 , further comprising:
a Bragg reflector along the V-shaped grooves; and
the shear-mode acoustic wave filter over the Bragg reflector.
16. The device according to claim 15 , wherein each opposing slope of the V-shaped grooves has an angle of 54.7 degrees or an angle between 10 degrees and 70 degrees.
17. The device according to claim 15 , wherein the Bragg reflector comprises layers of alternating high and low acoustic impedance thin-film material.
18. The device according to claim 15 , further comprising: pairs of vias through the thin-film piezoelectric layer and the first metal layer and optionally through the second metal layer, the thin-film piezoelectric layer, and the first metal layer down to the [100] crystal orientation Si layer, each via of each of the pairs of vias formed on an opposite side of the set of V-shaped grooves; and
a cavity in the [100] crystal orientation Si layer under the Bragg reflector, the cavity extending beyond the set of V-shaped grooves,
wherein the pairs of vias are formed through second metal layer when the second metal layer is the sheet.
19. The device according to claim 18 , wherein the set of V-shaped grooves comprises a row or a column of 10 V-shaped grooves, 10 rows or 10 columns of the 10 V-shaped grooves, or a plurality of V-shaped grooves.
20. A device comprising:
a set of a [111] V-shaped grooves in a [100] crystal orientation silicon (Si) layer over a substrate of sapphire, silica glass, or [111] crystal orientation Si, each opposing slope of the [111] V-shaped grooves having an angle between 10 degrees and 70 degrees;
a shear-mode acoustic wave filter over the set of the [111] V-shaped grooves, the shear-mode acoustic wave filter comprising a first metal layer, a thin-film piezoelectric layer, and a second metal layer in an interdigitated (IDT) pattern with a same or a different lateral width across the set of the [111] V-shaped grooves; pairs of vias through the thin-film piezoelectric layer and the first metal layer down to the [100] crystal orientation Si layer, each via of each of the pairs of vias formed on an opposite side of the set of the [111] V-shaped grooves; and
a cavity in the [100] crystal orientation Si layer under the shear-mode acoustic filter, the cavity extending beyond the set of the [111] V-shaped grooves.