Capacitive micro-electro-mechanical switch and method of manufacturing the same
View Patent ↗The present invention relates to a capacitive micro-electro-mechanical switch and method of manufacturing the same. In the capacitive micro-electro-mechanical switch for use in the radio frequency (RF) and the microwave driven by the electrostatic force, a capacitor of a 3-dimensional structure is formed on a signal transmission line. An ON capacitance is increased without increasing an capacitor area while preventing an increase in an OFF capacitance using the capacitor. Thus, an ON/OFF capacitance ratio of the capacitive micro-electro-mechanical switch can be increased and insertion loss and isolation characteristic could be improved.
1. A capacitive micro-electro-mechanical switch, comprising:
a first line form on a substrate;
an insulating layer having a hole through which a given region of the first line is exposed;
a capacitor of a 3-dimensional structure formed in the hole on the first line;
a metal post formed, on the insulating layer, in a direction vertical to the first lines from the capacitor; and
a second line spaced apart from the top of the capacitor by a given gap, wherein a portion of the second line is overlapped with the capacitor and an edge of the second line is fixed to the metal post in a direction vertical to the first line.
2. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein a plurality of holes are formed in the insulating layer, and wherein the capacitor has a stack structure of an assistant bottom electrode, a dielectric film and an assistant top electrode and each of the plurality of holes has shape with a 3-dimensional structure.
3. The capacitive micro-electro-mechanical switch as claimed in claim 2 , wherein the capacitor includes unit capacitors formed in every hole and the unit capacitors are in parallel connected one another.
4. The capacitive micro-electro-mechanical switch as claimed in claim 2 , wherein the assistant bottom electrode and the assistant top electrode are made of any one of Au, Al, W, Cu, TiN and Pt.
5. The capacitive micro-electro-mechanical switch as claimed in claim 2 , wherein the dielectric film is made of any one of Si 3 N 4 , Ta 2 O 5 , SrTiO 3 and Ba 0.5 Sr 0.5 TiO 3 .
6. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the capacitor has a 3-dimensional structure of a multi-layered shape including:
an assistant bottom electrode having multi-layered electrode layers connected one another at one edge of the first line and electrically connected to the first line;
an assistant top electrode having multi-layered electrode layers connected one another at the other edge of the first line, wherein the uppermost layer of the assistant top electrode is exposed; and
a dielectric film formed between the assistant bottom electrode and the assistant top electrode.
7. The capacitive micro-electro-mechanical switch as claimed in claim 1 , further comprising an adhesive layer between the substrate and the first line.
8. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the insulating layer is made of any one of silicate glass, PSG and BPSG.
9. The capacitive micro-electro-mechanical switch as claimed in claim 1 , further comprising a conductive contact pad on the capacitor.
10. The capacitive micro-electro-mechanical switch as claimed in claim 9 , wherein the contact pad is made of a noble metal or a conductive oxide layer.
11. The capacitive micro-electro-mechanical switch as claimed in claim 1 , further comprising ground lines on the substrate with the first line intervened, and wherein the metal post is electrically connected to the ground lines.
12. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the metal post is formed only 1 in number and is connected to the second line in a cantilever shape.
13. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the metal post is formed at both sides of the capacitor and both ends of the second line are fixed to the metal post.
14. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the metal post is made of any one of Au, Al, W, Cu, TiN, Pt and Ni.
15. The capacitive micro-electro-mechanical switch as claimed in claim 1 , wherein the second line is made of any one of Au, Al, W, Cu, TiN, Pt and Ni.