Wafer Bonding

MEMS devices and microfluidic chips are manufactured i.a. through eutectic bonding, anodic bonding, adhesive bonding or fusion / direct bonding.

The profound know how of Micronit GmbH allows the fabrication of  systems with up to 21 glass layers as well as closed chambers which can be used for reference pressure measurements in a chip. For MEMS applications free suspended membranes of oxide or nitride are required, which are build using bonding and back etching.

There are different wafer bonding techniques such as

  • Fusion bonding of silicon
  • Fusion resp. direct bonding of glass
  • Eutectic bonding
  • Anodic bonding
  • Thermo-compression bonding
  • Adhesive bonding

Fusion or Direct Bonding

Fusion or direct bonding is a technique whereby two or more wafers of the same material are joined together. Fusion bonding is conducted at high temperatures, which makes the bond as strong as the mechanical strength of the  base material. However, direct bonding at lower temperature is also feasible.

Technical Details

Technical Details

  • Integrated electrodes
  • Pressures resistance up to 400 bar
  • Glass bonding of different glass types, liek fused silica (quartz) or floaf glass line BF33®
  • Aligned bonding
  • Multi-stacks up to 21 layers (glass)
  • Starting with glass thicknesses of 145 µm
  • Structured or unstructured glass

Applications

Applications

  • Microfluidics, such als microreactors, micromixers
  • Cover of microfluidic channels
  • Sensors such as pressure sensors
  • Packaging
  • Channel port connections

Anodic Bonding

Anodic bonding is a bonding technique whereby two or more wafers of different materials (silicon with glass) are bound together. The bonding is done at low temperatures.

The process of anodic bonding is usually done at 400°C that is at lower temperatures as with direct bonding. For the European project BIOINTENSE Micronit developed a special low temperature bonding process at less than 180°C. The low temperature maintains the biological/chemical characteristic of the infused sensors and reduces the tension in glass and silicon layers.

Technical Details

Technical Details

  • Silicon to glass
  • SOI or SDOI to glass
  • Triple-stack-bonding (Glass-Si-Glass)
  • Aligned bonding
  • Vacuum bonding
  • Pressure definde bonding
  • Integration of electrodes
  • Integration of bio sensores, f.e. oxygen sensors
  • Hermetic connection

Applications

Applications

  • MEMS structures
  • MEMS sensors
  • Cover lid for microfluidic channels
  • Packaging
  • Channel port connections
  • BioMEMS devices
  • Lab-on-a-chip (LOC) or point-of-care (PoC)
  • MOMS

Eutectic Bonding

Using eutectic bonding means forging a material bound connection through application of pressure and temperature treatment between two silicon or glass wafers. An established eutectic alloy is gold-silicon.

Technical Details

Technical Details

  • Pressure up to 90 kN
  • Structures gold layser (thin film technique), not for adhesive
  • Combinations of other metals with silicon feasible, not for adhesive
  • Aligned bonding

Applications

Applications

  • MEMS packaging
  • 3D Integration
  • Microfluidics / Lab-on-a-chip
  • Through-connection (via)  f.e for BioMEMS

Adhesive Bonding

During adhesive bonding of PCB resp. SU-8 bonding polymers are applied to structures wafers and then structured with own layout. The bonding is done with a second wafer, which might be structured as well. Both wafers must not be necessarily of the same material.

Technical Details

Technical Details

  • Glas and /or silicon
  • Controlled heating & cooling-off
  • Structured PCB, SU-8 layers, other polymers as well
  • Integration of sensors, f.e. oxygen sensors
  • Integrated electrodes
  • Integration of functional layers

Applications

Applications

  • Lab-on-a-chip resp. Microfluidic structures
  • Optical sensors resp. Waver guides
  • IC devices
  • Isolating layers
  • BioMEMS
  • MEMS Packaging

If you have any questions or requests, please call +49 (0) 231 88 68 077