Method of manufacturing an acoustic mirror for a piezoelectric resonator
View Patent ↗A mirror for a piezoelectric resonator consisting of alternately arranged layers of high and low acoustic impedance is manufactured by at first producing a first layer on which a second layer is produced, so that the second layer partially covers the first layer. Then, a planarization layer is applied on the first layer and on the second layer. Subsequently, a portion of the second layer is exposed by structuring the planarization layer, wherein the portion is associated with an active region of the piezoelectric resonator. Finally, the resulting structure is planarized by removing the portions of the planarization layer remaining outside the portion.
1. A method of manufacturing an acoustic mirror of alternately arranged layers of high and low acoustic impedance, wherein the mirror comprises an alternating layer sequence of a plurality of layers with high acoustic impedance and a plurality of layers with low acoustic impedance, the method comprising:
(a) alternately producing the first layers and the second layers;
(b) applying a planarization layer on the structure produced in (a);
(c) exposing a portion of a topmost second layer, wherein the portion of the topmost second layer is associated with an active region of a piezoelectric resonator; and
(d) planarizing the structure from (c) by removing at least part of the planarization layer remaining outside the portion.
2. The method of claim 1 , wherein the topmost second layer is a conductive layer.
3. The method of claim 1 , wherein the exposing further comprises structuring the planarization layer using a mask.
4. The method of claim 3 , wherein the mask comprises a resist mask or a hard mask.
5. The method of claim 1 , further comprising applying an etch stop layer between the first layer and an initial second layer.
6. The method of claim 1 , wherein the first layer comprises a non-conductive layer, and wherein the second layer comprises a conductive layer.
7. The method of claim 1 , wherein the first layer comprises an oxide layer, and wherein the second layer comprises a tungsten layer.
8. The method of claim 1 , wherein the planarizing further comprises planarizing the structure such that a surface of the second layer and a surface of the planarization layer applied on the first layer are substantially flush.