Electrode structure with corrosion resistance and power durability
An apparatus for filtering is disclosed that implements an electrode structure with corrosion resistance and power durability. In an example aspect, the apparatus includes an acoustic filter with a piezoelectric layer and the electrode structure. The electrode structure is formed by a metal layer comprising copper and silicon and by an adhesion layer. The adhesion layer is deposited between the metal layer and the piezoelectric layer.
1 . An apparatus comprising:
an acoustic filter comprising:
a piezoelectric layer; and
an electrode structure formed by:
a metal layer comprising a combination of copper and silicon, wherein the copper forms a first part of the metal layer and the silicon forms a second part of the metal layer; and
an adhesion layer deposited between the metal layer and the piezoelectric layer.
2 . The apparatus of claim 1 , wherein the electrode structure comprises multiple fingers formed by the metal layer and the adhesion layer.
3 . The apparatus of claim 1 , wherein the electrode structure comprises at least one busbar formed by the metal layer and the adhesion layer.
4 . The apparatus of claim 1 , wherein:
the copper comprises copper atoms;
the silicon comprises silicon atoms;
an axis is approximately perpendicular to two opposite surfaces of the electrode structure and passes through the metal layer and the adhesion layer;
the copper atoms are distributed within the first part of the metal layer along at least a portion of the axis, and
the silicon atoms are distributed within the second part of the metal layer along at least the portion of the axis.
5 . The apparatus of claim 4 , wherein:
the two opposite surfaces of the electrode structure comprise a first surface that faces the piezoelectric layer and a second surface that is opposite the first surface; and
a concentration of the silicon atoms along the axis is higher proximate to the second surface compared to the first surface.
6 . The apparatus of claim 4 , wherein a quantity of the silicon atoms is between approximately half a percent and ten percent of a quantity of the copper atoms.
7 . The apparatus of claim 6 , wherein the quantity of the silicon atoms is between approximately one percent and five percent of the quantity of the copper atoms.
8 . The apparatus of claim 7 , wherein the quantity of the silicon atoms is approximately equal to two percent of the quantity of the copper atoms.
9 . The apparatus of claim 1 , wherein the metal layer comprises silver.
10 . The apparatus of claim 9 , wherein:
the silver comprises silver atoms;
an axis is approximately perpendicular to two opposite surfaces of the electrode structure and passes through the metal layer and the adhesion layer;
the two opposite surfaces comprise a first surface that faces the piezoelectric layer and a second surface that is opposite the first surface; and
a concentration of the silver atoms along the axis is higher proximate to the first surface compared to the second surface.
11 . The apparatus of claim 1 , wherein the adhesion layer comprises chromium.
12 . The apparatus of claim 1 , wherein:
the electrode structure is formed by a protection layer; and
the metal layer is deposited between the protection layer and the adhesion layer, wherein the protection layer is formed over the second part of the metal layer.
13 . The apparatus of claim 12 , wherein the protection layer comprises chromium.
14 . The apparatus of claim 1 , further comprising:
a wireless transceiver coupled to at least one antenna, the wireless transceiver comprising the acoustic filter and configured to filter, using the acoustic filter, a wireless signal communicated via the at least one antenna.
15 . The apparatus of claim 1 , wherein the acoustic filter comprises a surface-acoustic-wave filter.
16 . The apparatus of claim 15 , wherein the surface-acoustic-wave filter is without a compensation layer disposed on the metal layer of the electrode structure.
17 . The apparatus of claim 15 , wherein the surface-acoustic-wave filter comprises a thin-film surface-acoustic-wave filter.
18 . The apparatus of claim 15 , wherein the surface-acoustic-wave filter comprises a temperature-compensated surface-acoustic-wave filter.
19 . The apparatus of claim 1 , wherein the acoustic filter comprises a bulk-acoustic-wave filter.
20 . The apparatus of claim 1 , wherein a quantity of copper atoms in the first part of the metal layer is greater than a quantity of silicon atoms in the second part of the metal layer.
21 . A method of manufacturing an electrode structure of an acoustic filter, the method comprising:
providing an adhesion layer; and
providing a metal layer including a combination of a silicon layer and a copper layer on one side of the adhesion layer, wherein the copper layer forms a first part of the metal layer and the silicon layer forms a second part of the metal layer.
22 . The method of claim 21 , wherein the providing the adhesion layer comprises providing the adhesion layer between a piezoelectric layer of the acoustic filter and the silicon layer and the copper layer.
23 . The method of claim 21 , further comprising:
providing an additional layer on the one side of the adhesion layer, the additional layer comprising a material that provides stabilization for the copper layer.
24 . The method of claim 21 , wherein:
the copper layer comprises copper atoms;
the silicon layer comprises silicon atoms;
an axis is approximately perpendicular to two opposite surfaces of the electrode structure and passes through the copper layer and the silicon layer; and
the method further comprises diffusing the copper layer and the silicon layer to distribute the silicon atoms within the second part of the metal layer and the copper atoms within the first part of the metal layer along at least a portion of the axis.
25 . An apparatus comprising:
an acoustic filter comprising:
a piezoelectric layer; and
an electrode structure having a first surface that faces the piezoelectric layer and a second surface that is opposite the first surface, an axis being approximately perpendicular to the first surface and the second surface, the electrode structure comprising:
copper atoms forming a first part of the electrode structure;
silicon atoms forming a second part of the electrode structure, the silicon atoms having, along the axis, a higher concentration proximate to the second surface compared to the first surface, wherein the silicon atoms are distributed between at least a portion of the copper atoms; and
chromium atoms having, along the axis, a higher concentration proximate to the first surface compared to the second surface.
26 . The apparatus of claim 25 , wherein a quantity of the silicon atoms is between approximately half a percent and ten percent of a quantity of the copper atoms.
27 . The apparatus of claim 25 , wherein the electrode structure comprises silver atoms having, along the axis, a higher concentration proximate to the first surface compared to the second surface.
28 . An apparatus comprising:
an acoustic filter comprising:
a piezoelectric layer; and
an electrode structure formed by:
a metal layer comprising copper and silicon, wherein the copper comprises copper atoms and the silicon comprises silicon atoms, and wherein a quantity of the silicon atoms is between approximately half a percent and ten percent of a quantity of the copper atoms; and
an adhesion layer deposited between the metal layer and the piezoelectric layer;
wherein:
an axis is approximately perpendicular to two opposite surfaces of the electrode structure and passes through the metal layer and the adhesion layer; and
the copper atoms and the silicon atoms are distributed within the metal layer along at least a portion of the axis.
29 . The apparatus of claim 28 , wherein the electrode structure comprises multiple fingers formed by the metal layer and the adhesion layer.
30 . The apparatus of claim 28 , wherein the electrode structure comprises at least one busbar formed by the metal layer and the adhesion layer.