Variable radio frequency micro-electromechanical switch

Abstract

A radio frequency micro-electromechanical switch (generally referred to using the acronyms RF MEMS) is described. Also described is a method of producing such an RF MEMS switch.

1 . A radiofrequency micro-electromechanical switch, comprising:
 at least one of a semiconductor or insulating substrate having an planar face;   a first RF line capable of conveying an RF signal, the first RF line comprising at least one metal layer, the first RF line being arranged on the planar face of the substrate;   a second RF line capable of conveying an RF signal, the second RF line comprising at least one metal layer;   a MEMS membrane able to be deflected by at least one activation of the electrostatic type in one direction among a direction toward the substrate and a direction opposite the substrate, the MEMS membrane comprising at least one layer of metal and being parallel to the substrate and being connected to the first RF line at least one anchors;   a dome, having an inner face across from the planar face of the substrate and an outer face opposite the inner face, comprising at least one dielectric layer, the dome being arranged between the second RF line and the MEMS membrane, hermetically encapsulating the MEMS membrane in a cavity, and being anchored on the planar face of the substrate,   wherein the second RF line comprises at least a first section in contact with the face of the substrate, and a second section adjacent and electrically connected to the first section, the second section at least partially covering the upper part of the dome.   
     
     
         2 . The switch according to  claim 1 , wherein the MEMS membrane further comprises at least one dielectric layer. 
     
     
         3 . The switch according to  claim 1 , wherein the second section of the second RF line is at least partially inserted into the dielectric layer of the dome. 
     
     
         4 . The switch according to  claim 1 , further comprising at least one of:
 at least one upper activation electrodes electrically connected to one another and able to deflect the MEMS membrane through an electrostatic activation, the at least one upper activation electrode being arranged on the outer face of the dome   at least one central activation electrodes connected to one another electrically and able to deflect the MEMS membrane through an electrostatic activation, the at least one central activation electrode being arranged on the inner face of the dome   at least one lower activation electrodes connected to one another electrically and able to deflect the MEMS membrane through an electrostatic activation, the at least one lower activation electrode being arranged on the face of the substrate in the hermetic cavity.   
     
     
         5 . The switch according to  claim 4 , comprising at least one upper activation electrodes, each upper activation electrode being electrically connected to a central electrode by means of a metal via. 
     
     
         6 . The switch according to  claim 4 , comprising at least one stop pins arranged in the cavity so as to prevent any contact between at least one of the central and lower activation electrodes and the MEMS membrane when the MEMS membrane is deflected. 
     
     
         7 . The switch according to  claim 4 , wherein the dome includes at least one opening in which a metal pin is housed that is formed in the extension of the second section of the second RF line, such that the MEMS membrane and the second section of the second RF line are able to come into contact when the MEMS membrane is activated by an upper or central activation electrode so as to thus form an ohmic contact. 
     
     
         8 . The switch according to  claim 1 , wherein the dome comprises at least one dielectric layer separating the MEMS membrane and the second section of the second RF line, so as to form a Metal-Dielectric-Metal capacitance when the membrane is activated and in contact with the dome. 
     
     
         9 . The switch according to  claim 8 , wherein a layer of metal is arranged below the dielectric layer and comes into contact with the MEMS membrane when the MEMS membrane is deflected toward the dome. 
     
     
         10 . A radiofrequency micro-electromechanical microsystem comprising a switch as defined according to  claim 1 . 
     
     
         11 . A method for manufacturing a switch, comprising the following steps:
 a) depositing, on a planar face of at least one of a semiconductor and an insulating substrate, a first sacrificial layer and producing a pattern by at least one of lift-off and etching of a portion of the first sacrificial layer;   b) depositing, on the first sacrificial layer and on the planar face, at least a first layer of metal; then producing a pattern by at least one of lift-off and etching a portion of the layer of metal, to form the first RF line and the first MEMS membrane;   c) depositing, on the first RF line, a second sacrificial layer; then producing a pattern by at least one of lift-off and etching a part of the second sacrificial layer;   d) depositing, on the second sacrificial layer, a dielectric layer; then producing a pattern by at least one of lift-off and etching a portion of the dielectric layer, to form the dome having an inner face across from the planar face of the substrate, an outer face opposite the inner face, as well as at least one openings in the dome;   e) eliminating the first and second sacrificial layers through the openings; then   f) depositing, on the outer face of the dome and on the planar face of the substrate, at least one second metal layer; then producing a pattern making it possible to plug the openings and forming the second RF line by at least one of lift-off and etching of a portion of the second metal layer.   
     
     
         12 . The switch according to  claim 1 , wherein the MEMS membrane further comprises at least one additional metal layer.