Category Archives: Engineering

Microfluidics

Thin Film Services

Coating Technologies

GeSiM offers the deposition of conducting and insulating films by

  • Physical Vapor Deposition
  • Plasma-Enhanced Chemical Vapor Deposition
  • Screen Printing

 

Physical Vapor Deposition (PVD) by Magnetron Sputtering and Electron Beam Deposition

Can be applied to different materials:

  • Conductive materials: Aluminum (Al), titanium (Ti), platinum (Pt), tantalum (Ta):- Thickness from 0 to 200 Nanometers.
    – Resistance in the micro ohm range.
    – Patterning by lift-off and etching technologies.
    – Single-layer or multi-layer coating of these materials.
  • Conductive and transparent material ITO-90/10 (90% indium oxide In2O3 and 10% tin oxide SnO2):
    – Thickness from 20 to 200 Nanometers.
    – Resistance from 30 to 50 Ohm.
    – Patterning by lift-off and etching technologies.
  • Evaporated quartz SixOy, coated at 150° C.
Thin-Film_Examples-1

a) Platinum electrodes on glass, b) Thin film platinum resistors on a cantilever silicon nitride membrane, c) Aluminum metallization on a silicon chip, d) Gold electrodes on glass (From left to right)

 

Plasma Enhanced Chemical Vapor Deposition (PECVD)

  • Silicon oxide SiO2, silicon nitride Si3N4 and low stress oxinitride SixOyNz as alternative insulator materials:- Thickness from 20 Nanometers to 1.5 Microns.

    – Patterning by RIE dry etching and wet chemical etching.

  • Hydrofluorocarbon CxFy layers. Material similar to Teflon®:
    – Thickness range from 50 Nanometers to 2 Microns.
    – Patterning by O2 RIE plasma etching.

PVD and PECVD applies to all kind of substrates up to 4 inch diameter.

 

Screen Printing

  • Dispensing of the state of the art adhesives on printed circuit boards and micro system substrates for surface mounted device packaging.
  • Dispensing of silicon rubber.
  • Includes sieve design and production.
  • Typical thickness of printed materials in the range of 15 to 35 Microns.

 

Bonding

Connecting Microfluidic Chips with and without Glue

In order to achieve closed fludic channels MEMS technologies offers different – material dependent – methods. The GeSiM engineering service covers:

  • Anodic bonding
  • Silicon fusion bonding
  • Die bonding using adhesives
  • Wire bonding

 

Anodic Bonding

This process generates very tightly connected layers, produced by the application of high voltage and high temperature, and is ideal for the irreversible covering of microfluidic channels.

  • Bonding of double and triple sandwiches of silicon and Pyrex glass
  • Maximal substrate diameter: 4 inches (10 cm)
  • Process temperature between 300°C and 450°C.
  • Bonding with or without prealignment. Aligning accuracy ≥ 5 microns.
  • Bonding of insulator (Silicon oxide SiO2 or Silicon nitride Si3N4) silicon surfaces.

 

Silicon Fusion Bonding

  • Adhesive bonding after wet chemical pretreatment of substrates in strong acids
  • For double sandwiches of (micro-machined) silicon
  • Maximal substrate diameter: 4 inches (10 cm)
  • Process temperature between 950°C and 1100°C under nitrogen atmosphere

 

Die Bonding Using Adhesives

  • Computer Aided Design and sieve production for screen printing of adhesives
  • CAD and preparation of polymer spacers
  • Adhesive die bonding on whole wafers or on single chips
  • Aligning accuracy ≥ 5 microns
  • Usage of conductive adhesives to interconnect electrodes of top and bottom substrate of the die bonded sandwich
Bonding-Examples-2

a) Silicon-glass sandwich, b) Glass-silicon-glass sandwich (Patent 01993578.2-1524), c) 35 µm thick polymer layer on top of a glass wafer with SiO2– insulated platinum electrodes, d) Glass-polymer-glass flow through cell, assembled by die bonding using photolithographically patterned polymer spacer and screen printed adhesive Patent PCT/DE 01/03324) (From left to right)

Wire Bonding

  • On or between glass, silicon, ceramic, printed circuit boards with metal bond pads.
  • Wire material AlSi1, diameter: 25 microns.
  • Minimal bond pad area 30 x 30 microns².
  • Sealing of bond wires with epoxy.

 

 

Wafer Dicing Service

From the Batch Process to tiny Pieces

GeSiM accepts flat wafers with diameters up to 6 inch, furthermore tubes and objects of other geometries (please ask).

 

Substrate Materials

  • Silicon (up to 2 mm thick)
  • Different glasses (up to 1.5 mm thick)
  • Different Ceramics (up to 1.5 mm thick)
  • Stainless Steel (up to 1.0 mm thick)

 

Support

  • Pressure sensitive tapes
  • UV-curing tapes
  • Dicing wax
a) Glass capillary, diced into pieces of 1.5 mm length, b) Miniature mirrors, diced from a metallized 4 inch glass wafer, c) TEM cross section of a diced piece

a) Glass capillary, diced into pieces of 1.5 mm length, b) Miniature mirrors, diced from a metallized 4 inch glass wafer, c) TEM cross section of a diced piece (From left to right)

 

Instrumentation Service for R/D

Integrating the Worlds of Micro and Macrotechnology

The exchange of material and information with MEMS is more complex than with standard microelectronic chips. GeSiM offers customized solutions for packaging, liquid handling and instrument design.

  • Hybrid integration of Si or glass chips in ceramic of other wire bonding mounts,
  • Innovative electrical, fluidic and mechanical joining technology,
  • Integration of macrofluidic components (E.g. valves, pumps) or custom-specific parts,
  • Development of hard- and software,
  • Customization of GeSiM standard instruments.
Syringes_with_flowsensors

Multi-channel syringe module with flow sensors for supplying/removing fluids from microfluidic chips

 

 

Miscellaneous

Further MEMS Services

Microgalvanics

Galvanic deposition of thick layers of Ni (70 µm), Au (70 µm), Au (10 µm), after lift-off microstructuring

 

Screen Printing

  • Printing of SMD adhesives or silicone rubber on PCBs and microsystem substrates
  • Including sieve design and production
  • Typical thickness: 15 – 35 µm