Abstract
A MEMS component includes a lower electrode. The MEMS component also includes an upper electrode. The upper electrode overlies the lower electrode. The MEMS component also includes a first piezoelectric layer between the lower electrode and the upper electrode. The first piezoelectric layer has a first piezoelectric material comprising AlN and Sc.
Claims
1. A MEMS component comprising: a first lower electrode on a substrate; a first upper electrode overlying the first lower electrode; a first piezoelectric layer between the first lower electrode and the first upper electrode, wherein the first piezoelectric layer comprises Sc-doped AlN; a second lower electrode on the substrate; a second upper electrode overlying the second lower electrode; and a second piezoelectric layer between the second lower electrode and the first lower electrode, wherein the second piezoelectric layer is thicker than the first piezoelectric layer, and wherein the second piezoelectric layer has a different material composition than the first piezoelectric layer.
2. The MEMS component of claim 1, wherein the first lower electrode, the first piezoelectric layer and the first upper electrode form part of a first BAW resonator; and the second lower electrode, the second upper electrode and the second piezoelectric layer form a part of a second BAW resonator.
3. The MEMS component of claim 2, wherein the second piezoelectric layer comprises AlN.
4. The MEMS component of claim 2, wherein the second piezoelectric layer has an etching rate for a phosphoric acid solution that is different from an etching rate of the first piezoelectric layer for the phosphoric acid solution.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Examples of MEMS components and their manufacturing methods and the respective working principles are shown in the schematic figures.
(2) FIG. 1 shows a basic MEMS component with a piezoelectric layer PL1 between two electrode layers LE, UE;
(3) FIG. 2 shows a MEMS component with two BAW resonator stacks;
(4) FIG. 3 shows elements of a BAW component comprising acoustic minors;
(5) FIG. 4 shows a stage of a manufacturing process;
(6) FIG. 5 shows a stage of a manufacturing process;
(7) FIG. 6 shows a stage of a manufacturing process;
(8) FIG. 7 shows a final stage of a manufacturing process;
(9) FIG. 8 shows a component with piezoelectric switches with different thicknesses of piezoelectric material;
(10) FIG. 9 shows a component with further layers; and
(11) FIG. 10 shows a component with piezoelectric switches with different closing voltages.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
(12) FIG. 1 shows a MEMS component MC comprising a first piezoelectric layer PL1 between a lower electrode LE and an upper electrode UE. The first piezoelectric layer PL1 comprises the first piezoelectric material with AlN and Sc. This allows for a high-quality MEMS component with a structured first piezoelectric layer PL1, as methods for structuring Sc and AlN comprising piezoelectric material were found.
(13) FIG. 2 shows a MEMS component MC where a first BAW resonator BAWR1 is arranged next to a second BAW resonator BAWR2. Both resonators can be arranged on or above a carrier substrate CS. Both resonators comprise a lower electrode LE and an upper electrode UE. At least the first BAW resonator BAWR1 comprises a first piezoelectric material. Piezoelectric layers PL1, PL2 and the electrodes LE, UE establish a first lamination LS1 and a second lamination LS2 of the resonator, respectively, in which an acoustic wave is excited when an RF signal is applied to the respective electrodes. The piezoelectric layer PL2 of the second BAW resonator BAWR2 is thicker than the piezoelectiric layer PL1 of the first resonator BAWR1. Thus, both resonators have different resonance frequencies although they can be manufactured by means of easy-to-perform manufacturing steps one next to the other on or above a common carrier substrate CS.
(14) FIG. 3 shows main components of a BAW component BAWC where mainly the top electrode is omitted. Two resonator stacks are arranged on respective acoustic mirrors AM. The acoustic minors AM comprise a layer system with alternating high and low acoustic impedance. The acoustic minor AM confines acoustic energy and allows establishing a resonance mode of the respective resonator.
(15) FIG. 4 shows a stage during one of several possible manufacturing processes where two layer stacks are arranged next to each other on a common carrier substrate CS. After depositing and structuring a lower electrode LE, the first piezoelectric layer PL1 is deposited and structured on the lower electrode LE of at least one layer stack.
(16) FIG. 5 shows an optional stage of a manufacturing process where a resist layer RES is arranged on the second piezoelectric material. If the first and the second piezoelectric materials have the same composition, an etching agent will etch both materials at the same rate. If the layer thicknesses are to be different, one stack, i.e. the stack with the second piezoelectric material, may be covered with the resist layer RES. If the two piezoelectric materials are of different composition, a different etching rate can be obtained and no resist layer is needed to obtain different thicknesses.
(17) Accordingly, FIG. 6 shows a stage during which a difference in layer thickness is obtained by etching the first piezoelectric layer PL1.
(18) Although it is in principle possible to adjust the thicknesses by etching it is preferred to adjust the thicknesses by depositing material. To obtain different thicknesses one layer stack can have an additional layer. Then, phosphoric acid can be used to structure resonator stacks comprising Sc and AlN.
(19) FIG. 7 shows a final manufacturing stage where an upper electrode UE has been deposited and structured on both layer stacks to yield respective BAW resonators BAWR1, BAWR2.
(20) FIG. 8 shows another embodiment of the MEMS component where additional piezoelectric layers APL are arranged between the first PL1 and the second piezoelectric layer PL2, respectively, on one side and the upper electrode UE on the other side. A difference in the thickness of the piezoelectric material is obtained by providing a thickness difference between the first PL1 and the second PL2 piezoelectric layers.
(21) FIG. 9 shows an embodiment of the MEMS component where additional layers AL are arranged between the piezoelectric and/or electrode layers. One or more additional layers AL can be seed layers, adhesion layers, passivation layers, further piezoelectric layers or anti-acoustomigration layers.
(22) FIG. 10 shows a BAW component where a lamination comprising a first piezoelectric layer PL1 and a second piezoelectric layer PL2 are each arranged between a respective lower electrode LE upper electrode UE to establish a first cantilever-shaped switch SW1, and a second cantilever-shaped switch SW2. The switches are arranged next to each other on the same carrier substrate. The different constructions of the two switches allow different closing voltages.
(23) Neither the MEMS component nor the method for manufacturing such a MEMS component are limited to the embodiments described in the specification or shown in the figures. Components and methods comprising further materials or layers or components comprising further resonators or methods comprising further deposition steps or etching steps or combinations thereof are also covered by the present invention.
