Bulk-acoustic wave resonator
A bulk-acoustic wave resonator includes: a substrate; a first electrode disposed on the substrate; a piezoelectric layer disposed to cover at least a portion of the first electrode; a second electrode disposed to cover at least a portion of the piezoelectric layer; a metal pad connected to the first electrode and the second electrode; and a connection member connected an upper surface of the metal pad. A lower end portion of the connection member includes a tapered portion decreasing in a diameter in a direction toward a lower end of the connection member, and an angle between an inclined surface of the tapered portion and the upper surface of the metal pad is 45° to 80°.
1. A bulk-acoustic wave resonator, comprising:
a substrate;
a first electrode disposed on the substrate;
a piezoelectric layer disposed to cover at least a portion of the first electrode;
a second electrode disposed to cover at least a portion of the piezoelectric layer;
a metal pad connected to the first electrode and the second electrode; and
a connection member connected an upper surface of the metal pad,
wherein an upper end portion of the connection member includes a cylindrical portion having a constant diameter,
wherein a lower end portion of the connection member includes a tapered portion disposed below the cylindrical portion and decreasing in a diameter in a direction toward the lower end of the connection member,
wherein an angle between an inclined surface of the tapered portion and the upper surface of the metal pad is 45° to 80°, and
wherein a diameter of a bottom surface of the tapered portion is 60 μm or more.
2. A bulk-acoustic wave resonator, comprising:
a substrate;
a first electrode disposed on the substrate;
a piezoelectric layer disposed to cover at least a portion of the first electrode;
a second electrode disposed to cover at least a portion of the piezoelectric layer;
a metal pad connected to the first electrode and the second electrode; and
a connection member connected an upper surface of the metal pad,
wherein a lower end portion of the connection member includes a tapered portion decreasing in a diameter in a direction toward the lower end of the connection member, the tapered portion has a height of 6 μm or more, and an angle between an inclined surface of the tapered portion and the upper surface of the metal pad is 45° to 80°.
3. The bulk-acoustic wave resonator of claim 2 , wherein an upper end portion of the connection member includes a cylindrical portion having a constant diameter, and wherein the tapered portion is disposed below the cylindrical portion.
4. The bulk-acoustic wave resonator of claim 3 , wherein a diameter of a bottom surface of the tapered portion is 60 μm or more.
5. The bulk-acoustic wave resonator of claim 2 , wherein the connection member is made of any one of gold (Au), a gold-tin (Au—Sn) alloy, copper (Cu), a copper-tin (Cu—Sn) alloy, and aluminum (Al), and an aluminum alloy, or a material containing any two or more of gold (Au), a gold-tin (Au—Sn) alloy, copper (Cu), a copper-tin (Cu—Sn) alloy and aluminum (Al), and an aluminum alloy.
6. The bulk-acoustic wave resonator of claim 2 , further comprising an insertion layer disposed between the first electrode and the piezoelectric layer.
7. The bulk-acoustic wave resonator of claim 2 , further comprising a membrane layer forming a cavity together with the substrate.
8. The bulk-acoustic wave resonator of claim 7 , further comprising:
an etch stop portion disposed to surround the cavity; and
a sacrificial layer disposed to surround the etch stop portion.
9. The bulk-acoustic wave resonator of claim 7 , wherein the membrane layer comprises an inclined portion disposed obliquely with respect to an upper surface of the substrate, and a flat portion disposed in an active region in which the first electrode, the piezoelectric layer, and the second electrode all overlap one another.
10. The bulk-acoustic wave resonator of claim 9 , wherein the second electrode includes a frame disposed at an edge of the active region, and wherein the frame has a thickness greater than a thickness of a remainder of the second electrode.
11. The bulk-acoustic wave resonator of claim 7 , further comprising an insulating layer disposed on the substrate, below the cavity.
12. The bulk-acoustic wave resonator of claim 2 , wherein the metal pad comprises a first metal pad connected to the first electrode, and a second metal pad connected to the second electrode.
13. A bulk-acoustic wave resonator, comprising:
a substrate;
a first electrode disposed on the substrate;
a piezoelectric layer disposed to cover at least a portion of the first electrode;
a second electrode disposed to cover at least a portion of the piezoelectric layer;
a metal pad connected to the first electrode and the second electrode; and
a connection member connected to an upper surface of the metal pad,
wherein the connection member comprises:
a cylindrical portion disposed at an upper end portion of the connection member and having a constant diameter; and
a tapered portion disposed below the cylindrical portion, the tapered portion having a height of 6 μm or more and a diameter that is smaller at a lower end of the tapered portion than an upper end of the tapered portion.
14. The bulk acoustic wave resonator of claim 13 , wherein a bottom surface of the tapered portion is in contact with the upper surface of the metal pad.
15. The bulk acoustic wave resonator of claim 14 , wherein a diameter of the bottom surface of the tapered portion is 60 μm or more.