Method of manufacturing an acoustic mirror for a piezoelectric resonator and method of manufacturing a piezoelectric resonator

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 the piezoelectric resonator;
• and
• (d) planarizing the structure from (c) by removing at least part of the planarization layer remaining outside the portion.

A method of manufacturing a piezoelectric resonator, the method comprising:

• (a) producing 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 producing comprising:
• (a.1) alternately producing the first layers and the second layers;
• (a.2) applying a planarization layer on the structure produced in (a.1);
• (a.3) exposing a portion of a topmost second layer by structuring the planarization layer, wherein the portion of the topmost second layer is associated with an active region of the piezoelectric resonator;
• and (a.4) planarizing the structure from (a.3) by removing the portions of the planarization layer remaining outside the portion;
• (b) producing a lower electrode substantially at least partially on the acoustic mirror;
• (c) producing a piezoelectric layer at least partially on the lower electrode;
• (d) producing an upper electrode at least partially on the piezoelectric layer, wherein a region in which the upper electrode, the piezoelectric layer, and the lower electrode overlap, defines an active region of the piezoelectric resonator.