Mechanical landing pad formed on the underside of a MEMS device

DETAILED DESCRIPTION Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention.
Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.
Variations on a device with the inventive landing pad structure are depicted in FIGS.
1A-1C.
In a first embodiment of the invention, depicted in FIG.
1A, a basic device 100 includes a device layer 102 and at least one landing pad 104 protruding from an underside 106 of device layer 102.
Landing pad 104 is attached to device layer 102 by a plug 108 passing through an opening 110 in device layer 102.
The landing pad provides a smaller contact area 112 than an area of underside 106.
The smaller contact area serves to reduce stiction between device 100 and an underlying substrate 90.
Stiction may also be reduced by proper choice of the material comprising landing pad 104.
Device 100 may be any type of electromechanical device.
Suitable devices include side-actuated motors, and electromagnetically or thermally actuatable mirrors for optical switches.
Device layer 102 is typically a semiconductor material such as silicon, although other possible materials including metals and dielectrics may also be used.
Depending on the specific application, landing pad 104 may be made from a dielectric material, such as silicon nitride, or a metal, such as Tungsten, titanium nitride or the like.
Alternatively the landing pad may be made from polycrystalline silicon or other similar material.
Two variations on the basic device 100 are depicted in FIGS.
1B and 1C.
FIG.
1B depicts a second embodiment of the invention.
The basic structure of the device in this embodiment shares features in common with device 100 of FIG.
1A.
In the second embodiment, a device 120 includes at least one landing pad 124 having a diameter greater than a plug 126