Mems switch with beam contact portion continuously extending between input and output terminal electrodes

Abstract

Embodiments of the disclosure are directed to microelectromechanical system (MEMS) switches with a beam contact portion continuously extending between input and output terminal electrodes. In exemplary aspects disclosed herein, the movable beam includes a body and a contact with more conductivity and stiffness than the body. The contact continuously extends between and electrically couples the contact of the movable beam with the input and output terminal electrodes. Differing materials between the body and the contact allow for inclusion of the mechanical properties of the body (e.g., to reduce mechanical fatigue, creep, etc.) while utilizing the electrical properties of the contact (e.g., to reduce on-state electrical resistance). Accordingly, the MEMS switch provides low resistance loss during an on-state while maintaining high levels of isolation during an off-state.

1 . A microelectromechanical system (MEMS) switch, comprising:
 an input terminal electrode;   an output terminal electrode;   a pull-down electrode positioned between the input terminal electrode and the output terminal electrode; and   a movable beam positioned proximate the input terminal electrode and the output terminal electrode, the movable beam comprising:
 a body comprising a first conductivity and first stiffness; and 
 a contact comprising a second conductivity and a second stiffness more than the first conductivity and the first stiffness, the contact proximate to and continuously extending between the input terminal electrode and the output terminal electrode to limit on-state resistance therebetween; the movable beam configured to move between: 
 an on-state electrically coupling the contact of the movable beam with the input terminal electrode and the output terminal electrode; and 
 an off-state electrically isolating the contact of the movable beam from the input terminal electrode and the output terminal electrode. 
   
     
     
         2 . The MEMS switch of  claim 1 , wherein the input terminal electrode comprises an input RF electrode, and the output terminal electrode comprises an output RF electrode. 
     
     
         3 . The MEMS switch of  claim 1 , wherein the movable beam is coupled to an RF node. 
     
     
         4 . The MEMS switch of  claim 1 , wherein the body comprises at least one of TiAl or TiAlN. 
     
     
         5 . The MEMS switch of  claim 1 , wherein the contact comprises at least one of ruthenium, ruthenium oxide, platinum, or gold. 
     
     
         6 . The MEMS switch of  claim 1 , wherein the contact has a thickness between about 30 to 80 nm. 
     
     
         7 . The MEMS switch of  claim 1 , wherein a length of the contact is between 1% to 50% longer than a length between the input terminal electrode and the output terminal electrode. 
     
     
         8 . The MEMS switch of  claim 1 , wherein end portions of the contact are wider than a middle portion of the contact. 
     
     
         9 . The MEMS switch of  claim 1 , wherein the contact defines an aperture. 
     
     
         10 . The MEMS switch of  claim 1 , wherein:
 the input terminal electrode comprises a plurality of input terminal electrodes;   the output terminal electrode comprises a plurality of output terminal electrodes; and   the contact continuously extends over each of the plurality of input terminal electrodes and the plurality of output terminal electrodes.   
     
     
         11 . The MEMS switch of  claim 1 , wherein the movable beam is mechanically biased toward the off-state. 
     
     
         12 . The MEMS switch of  claim 1 , further comprising a pull-up electrode configured to electrically bias the movable beam toward the off-state. 
     
     
         13 . The MEMS switch of  claim 1 ,
 further comprising a substrate;   wherein the input terminal electrode, output terminal electrode, and pull-down electrode are mounted on the substrate;   wherein ends of the movable beam are mounted to the substrate such that the movable beam is suspended above the input terminal electrode, output terminal electrode, and the pull-down electrode in the off-state.   
     
     
         14 . The MEMS switch of  claim 13 ,
 further comprising a cover mounted to the substrate and defining a cavity between the cover and the substrate;   wherein the movable beam is positioned within the cavity.   
     
     
         15 . A microelectromechanical system (MEMS), comprising:
 a plurality of MEMS switches, each switch comprising:
 an input terminal electrode; 
 an output terminal electrode; 
 a pull-down electrode positioned between the input terminal electrode and the output terminal electrode; and 
 a movable beam positioned proximate the input terminal electrode and the output terminal electrode, the movable beam comprising:
 a body comprising a first conductivity and a first stiffness; and 
 a contact comprising a second conductivity and a second stiffness more than the first conductivity and the first stiffness, the contact proximate to and extending between the input terminal electrode and the output terminal electrode to limit on-state resistance therebetween; 
 
 the movable beam configured to move between:
 an on-state electrically coupling the contact of the movable beam with the input terminal electrode and the output terminal electrode; and 
 an off-state electrically isolating the contact of the movable beam from the input terminal electrode and the output terminal electrode. 
 
   
     
     
         16 . The MEMS device of  claim 15 , wherein for each MEMS switch, the body comprises at least one of TiAl or TiAlN, and the contact comprises at least one of ruthenium, ruthenium oxide, platinum, or gold. 
     
     
         17 . The MEMS device of  claim 15 , wherein for each MEMS switch, the contact has a thickness between about 30 to 80 nm. 
     
     
         18 . The MEMS device of  claim 15 , wherein for each MEMS switch, a length of the contact is between 1% to 50% longer than a length between the input terminal electrode and the output terminal electrode. 
     
     
         19 . The MEMS device of  claim 15 , wherein for each MEMS switch, end portions of the contact are wider than a middle portion of the contact. 
     
     
         20 . The MEMS device of  claim 15 , wherein for each MEMS switch, the contact defines an aperture.