US 6,396,368 B1 · CMOS-compatible MEM switches and method of making

Abstract

A microelectromechanical (MEM) switch is fabricated inexpensively by using processing steps which are standard for fabricating multiple metal layer integrated circuits, such as CMOS. The exact steps may be adjusted to be compatible with the process of a particular foundry, resulting in a device which is both low cost and readily integrable with other circuits. The processing steps include making contacts for the MEM switch from metal plugs which are ordinarily used as vias to connect metal layers which are separated by a dielectric layer. Such contact vias are formed on either side of a sacrificial metallization area, and then the interconnect metallization is removed from between the contact vias, leaving them separated. Dielectric surrounding the contacts is etched back so that they protrude toward each other. Thus, when the contacts are moved toward each other by actuating the MEM switch, they connect firmly without obstruction. Tungsten is typically used to form vias in CMOS processes, and it makes an excellent contact material, but other via metals may also be employed as contacts. Interconnect metallization may be employed for other structural and interconnect needs of the MEM switch, and is preferably standard for the foundry and process used. Various metals and dielectric materials may be used to create the switches, but in a preferred embodiment the interconnect metal layers are aluminum and the dielectric material is SiO2, materials which are fully compatible with standard four-layer CMOS fabrication processes.

Claims19

Dependent claims

A microelectromechanical switch comprising:

a moveable armature having a first position and a second position;
a foundation relative to which said armature moves;
actuation-force regions for applying a force between said armature and said foundation to move the armature from the first position to the second position;
and
at least one mating contact pair, each mating contact pair including at least one contact point on said armature and at least a second contact point on said foundation, the mating contacts contacting each other when the armature is in the second position and being separated from each other when the armature is in the first position;
wherein at least one of said contact points includes tungsten and each contact point of said mating contact pair protrudes through partially surrounding dielectric material towards a mating contact point.

3 more elements

A microelectromechanical switch structure comprising:

a foundation relative to which said armature moves, said foundation having a metal lower plate;
a moveable armature moving relative to said foundation and having a first position and a second position, said armature comprising:
an anchor portion disposed on said foundation;
a cantilever portion having a proximal end and a distal end, said proximal end disposed at said anchor portion;
and
an armature portion disposed at said distal end, said armature portion having a metal upper plate disposed above said lower plate;
a switch contact electrically connected to said upper plate, wherein a voltage applied between said switch contact and said lower plate moves the armature from the first position to the second position;
and
at least one mating contact pair, each mating contact pair including at least one contact point on said armature and at least a second contact point on said foundation, the mating contacts contacting each other when the armature is in the second position and being separated from each other when the armature is in the first position,
wherein the electrical connection between the switch contact and the upper plate comprises a vertical via disposed within said anchor portion and a conducting strip disposed on or within said cantilever portion and connecting said vertical via to said upper plate.

7 more elements

Dependencies are inferred from the claim text.

CMOS-compatible MEM switches and method of making

Life of this patent

CMOS-compatible MEM switches and method of making

Life of this patent

Abstract

Claims19