Direct bonding is done at high temperature, which makes the bond very strong (high-pressure resistant - to 150 bar / 2175 psi). Bonding defects rarely occur. Most of the times, a glass layer with holes is bonded to another glass layer with channels. Alignment is very accurate.

Bonding of three or four layers is no problem for us.

Micronit is one of the few companies in microtechnology that offers direct glass to glass and glass to silicon bonding (without an intermediate layer).

Process
In the figures below three different possible processes are shown. Depending on the designs of chips or structured wafers the processes can be mixed or other possibilities can be added.

    A. Standard Process                              B. Thin Bottom Process                         C. Integrated Electrodes

    Top substrate (1.1 mm or 700             Top substrate (1.1 mm or 700             Top substrate (1.1 mm or 700
    µm) with powderblasted holes            µm) with powderblasted holes            µm) with powderblasted holes
    is bonded to bottom substrate             and HF etched or powder-                   and HF etched or powder-
    (1.1 mm or 700 µm) with HF                blasted channels is bonded to            blasted channels is bonded to
    etched or powderblasted                      bottom substrate of 175 µm.                bottom substrate with 
    channels.                                                                                                                     electrodes.