Package, Process & Microassembly

Research that includes:

  • Low temperature MEMS-on-CMOS Silicon-Germanium process for adding MEMS to finished CMOS wafers or dice
  • Silicon Carbide process for adverse environment MEMS and high frequency RF resonators
  • Localized bonding: eutectic, fusion, solder, laser, inductive, rapid thermal processing, and ultrasonic; suitable for device level or wafer level packaging or sealing applications to plastic, glass, silicon and Bio materials, including liquid encapsulation
  • Fluidic microassembly for post-process combining of dissimilarly processed microdevices
  • Carbon nanotube and silicon nanowire directional growth in post-process, low ambient temperature environments
  • Stiction mitigation for MEMS

RTH35: Novel SiGe Processes for Electrostatically Actuated MEMS Resonators

Carrie Low
2006

As an alternative material for surface micromachining, polycrystalline silicon-germanium (poly-SiGe) has comparable processes and material properties to polycrystalline silicon (poly-Si). Its low processing temperature is the major advantage of poly-SiGe as it enables post-CMOS integration of MEMS. This modular approach to MEMS integration is an attractive route to higher performance and lower cost microsystems.

Project end date: 01/24/07

APP77: MEMS Strain Gauge on Steel: Elastic Encapsulation

Robert G. Azevedo
2006

The MEMS strain gauge on steel project aims to design a MEMS strain gauge that can be bonded directly to steel and accurately measure strain in small strain fields (gauge length of 1 mm or less). Encapsulation of the MEMS strain gauge, in contrast to microelectronics or inertial force sensor packaging, requires that the package be a mechanical transducer of the measurand to the sense elements. To meet the objective of hermetic, minimally-aliasing encapsulation of the strain gauge, we propose an elastic, wafer-level solution.

Project end date: 01/26/07

RM5/RTH: Silicon carbide process development and characterization for harsh-environment sensors

Jingchun Zhang
Carlo Carraro
2007

Silicon carbide (SiC) is a wide band gap semiconductor with extraordinary properties and has attracted considerable attention for high temperature electronics. Recently, this material is being pursued for microelectromechanical systems (MEMS) applications in harsh environments. The goal of this project is to develop a series of SiC-based sensors and to characterize them for harsh environments. In order to achieve thisgoal, a series of microfabrication technologies including low-temperature CVD, reactive ion etching, and metalization of poly-SiC films need to be developed. In addition...

LWL24: Rapid Bonding of MEMS Strain Gauge to Steel

Brian D. Sosnowchik
Ko-Min Liao
2007

A rapid and reliable bonding method is needed to bond MEMS strain gauges to steel. The MEMS strain gauge is to be bonded to the manufactured steel after all other steel treatment steps have been completed; hence the bonding method must be kept at low temperature to prevent any thermal damage to the steel composition. In addition, the bonding method must not introduce high residual strains, which would cause error in strain gauge measurements. The strain gauge to steel bond must also have the ability to survive several years in a wide working temperature range (-60oC to 150oC) in an...

RTH42: Nanowire-Coupled Resonators

Noel Arellano
2007

We have developed fabrication processes to create top down nanowire coupled resonators. The critical dimensions were defined using a combination of iline lithography, photoresist ashing techniques and focused ion beam trimming. Nanowires are used as mechanical elements to demonstrate low velocity and maximum velocity coupling. We have also demonstrated an bottom up/ top down integrated fabrication process. Features for the top down segment of the fabrication process are aligned to (111) flat on a (110) SOI wafer. A gold based galvanic displacement method selectively deposits catalyst...

BPN306: SiC TAPS: Ion Beam Assisted Deposition (IBAD) Encapsulation

Debbie G. Jones
2007

The goal of this project is to develop a low temperature, wafer-level vacuum encapsulation technique for harsh environment, silicon carbide (SiC) sensors.

Project end date: 08/07/07

BPN389: SiC TAPS: Characterization of Silicon Carbide Ion Beam Assisted Deposition (IBAD) Films

Matt Chan
2007

Silicon Carbide (SiC) is an appealing material for harsh environment MEMS applications. It can be sputtered at low temperatures by an Ion-Beam Assisted Deposition (IBAD) system to produce amorphous thin-films and vacuum encapsulations. The goal of this project is to investigate the stress-temperature relation of these amorphous SiC films in order to calculate their biaxial moduli and coefficients of thermal expansion. The “double-substrate technique” is employed to compare the differences in these properties for films that are sputtered both with and without ion-beam assistance...

BSAC5: VUV Lamp Assembly for Wafer Scale Surface Modification

Matthew Wasilik
2007

Liftoff is a processing technique often preferred for patterning metal thin films. In a liftoff process, the resist is patterned first, and then the metal film is deposited. After metal deposition, the resist is dissolved and – if the process has been optimized to insure poor metal step coverage - the unwanted metal is removed (“lifted off”) from the regions where the remaining resist is dissolved. Liftoff is preferable for difficult to etch metals, in cases where the metal etch has a poor selectivity relative to underlying layers and in situations that require minimizing...

BPN387: Modeling of Temperature Effects on Piezoresistor Sensitivity

Zachary Lee
2007

Joule heating occurs in any conductor when current passes through it due to the resistance of the conductor. Semiconductor strain gauges in particular are very susceptible to such temperature changes as they can cause significant fluctuations in the resistance of the gauge itself. This is generally referred to as self-heating of the strain gauge. Self-heating effects are undesirable as they can drastically decrease the signal-to-noise ratio of the strain gauges. In order to improve the sensitivity of a strain gauge it is of interest to characterize the thermal effects of the current...

APP80: Micro Plastic Injection Molding: Microneedle Molding

Julian Lippmann
2007

This project along with APP79 investigates the manufacturing and integration of um scale plastic parts through injection molding. Emphasis is placed on developing robust, but simple fabrication methods capable of molding microneedles 100um X 100um hollow tubes. The issues to be addressed span the micro and meso regimes. At the microscale effort focuses on creating accurate, robust molds that can deliver MEMS scale needles. On the mesoscale, Plastic injection materials and processes are being investigated to yield optimum results.

Project end date: 01/23/08