A photolithographically patterned spring contact is formed on a substrate and electrically connects contact pads on two devices. The spring contact also compensates for thermal and mechanical variations and other environmental factors. An inherent stress gradient in the spring contact causes a free portion of the spring contact to bend up and away from the substrate. An anchor portion remains fixed to the substrate and is electrically connected to a first contact pad on the substrate. The spring contact is made of an elastic material and the free portion compliantly contacts a second contact pad, thereby electrically interconnecting the two contact pads.

Photolithographically patterned spring contact

Integrated high-Q coils are much sought after because they enable high-quality radio-frequency circuits that do not rely on off-chip discretes. We present a novel surface micro-machined inductor with its coil axis parallel to the substrate plane. Coils fabricated on standard unaltered low-resistance silicon exhibit record-high-quality factors (Q) of over 70 at 1 GHz. The devices are made by three-dimensional (3-D) self-assembly of stress-engineered structures fabricated with standard semiconductor batch processing techniques. We also designed, fabricated, and characterized silicon Bi-CMOS L-C oscillators built around these coils. Compared side by side against state-of-the-art planar spirals, they produce a 12.3 dB lower phase noise at 100 kHz offset, and 14.6 dB after normalizing to frequency and power.

Out-of-plane high-Q inductors on low-resistance silicon

Photolithographically patterned spring contact and apparatus and methods for electrically contacting devices

A novel external electrode concept is introduced and compared with the conventional and often used parallel plate electrode scheme for the electrostatic actuation of micro-electromechanical devices. In contrast to conventional parallel plate actuation, the presented external electrode configuration allows controlled operation of electrostatic actuators over their entire range of motion by avoiding electrostatic instability. The test vehicle for studying deflection versus voltage is a cantilevered beam with a free end, i.e. the worst-case scenario from a stability standpoint. Modeling and fabrication of test devices is discussed and experimental results are presented.

https://iopscience.iop.org/article/10.1088/0960-1317/14/4/003/pdf

A novel external electrode configuration for the electrostatic actuation of MEMS based devices

Disclosed is a MEMS device which comprises at least one shape memory material such as a shape memory alloy (SMA) layer and at least one stressed material layer. Examples of such MEMS devices include an actuator, a micropump, a microvalve, or a non-destructive fuse-type connection probe. The device exhibits a variety of improved properties, for example, large deformation ability and high energy density. Also provided is a method of easily fabricating the MEMS device in the form of a cantilever-type or diaphragm-type structure.

Stressed material and shape memory material MEMS devices and methods for manufacturing

We have used sputter-deposition and standard lithography to fabricate arrays of cantilevered metal micro-springs on 80 /spl mu/m pitch, and we have obtained 100% electrical contact to 200-pad chips bonded face-down against them. Four-point resistance is 0.38 /spl Omega/ for Mo-Cr springs on Al pads. Since the contacts themselves are not bonded and since the springs have high elastic compliance, this technology is very resistant to mechanical shock and stress, can accommodate large nonplanarity in mating surfaces, facilitates replacement of bad chips, and could be used for wafer-scale probing.

A.S. Alimonda

Papers

A new flip-chip technology for high-density packaging