Anodic Bonding

Anodic bonding joins to substrates using an electric field an elevated temperatures. It is essential that one of the substrates is able to create mobile ions which can oxidise the surface of the partner at their interface. The other substrate needs to be (at least slightly) electrically conducting.

This way alkaline containing glasses or ceramics can be bonded to metals and semiconductors. Anodic bonding of BF33 and silicon is commonly used in microsystems technology. Fig. 6 and 7 show the front and back side of an anodic bonded micro reactor consisting of a wet chemically micromachined silicon substrate and a mechanically processed BF33.

Anodic bonding allows to sequentially bond various aligned substrates. Fig. 8 shows the cross section of stack of BF33/Si/BF33 bonded together. The silicon substrate contains DRIE etched fluidic channels and feed-throughs. The BF33 has been structured by ultrasonic drilling.

Fig. 6: Front side of an anodic bonded micro reactor, silicon side
Fig. 7: Back side of micro reactor, glass side
Fig. 8: Bonded stack consisting of BF33/Si/BF33