Glass-Glass Wafer Bonding for Microfluidic Devices

The AML AWB04 wafer bonding platform has been used to develop glass – glass bonding processes for both quartz and Pyrex substrates. This allows the accurate wafer to wafer alignment and bonding of two microfluidic (or any other glass device) wafers. In the case of Quartz, the process is also useful in the field of SAW (Surface Acoustic Wave) device fabrication. Although there are simpler and cheaper ways of creating micro fluidic devices (e.g adhesive bonded glass wafers, or all polymer devices), Pyrex is often required as the material is qualified for use in pharmaceutical and medical industries. The transmission properties of glass are also often needed where optical sensing and measurement is required. Pyrex is often needed for chemical compatibility, and is commonly used for glassware. Using the AML equipment, Pyrex and Quartz devices can be sealed at the wafer level with placement accuracies approaching ±1μm. The bonding process can also seal vacuum cavities, or seal controlled atmosphere cavities (e.g. reference cavities for optical absorption measurements). It is sometimes important to maintain precise glass micromachining dimensions and therefore it is necessary to bond at a temperature substantially less than the strain point of the glass: the AML equipment and processes can achieve this. The sealing strength is sufficient to withstand high pressure fluidic applications.