Flip-Chip Fabrication of Advanced Microelectromechanical Systems and Integrated Microsystems.

摘要

One of the most enabling features of any Microelectromechanical Systems (MEMS) fabrication service is the number of structural layers available to the designer of surface-micromachined components. The complexity and capabilities of such devices increases significantly with the number of structural layers since more intricate mechanisms can be created and there are more choices in the thickness and height of any desired structure. Commercial foundries, however, limit designers to very few choices of materials or number of structural layers. As a result, it may not be possible to create many specialized devices required for more demanding applications without custom fabrication methods which are usually very expensive. As an alternative, this research has demonstrated a novel, simple, repeatable, reliable, and inexpensive post-process flip-chip assembly technique that was developed to use existing fabrication processes. Commercial foundries have fully optimized fabrication for increased yield, turn-around time, and reduced cost. Therefore, rather than develop an entirely new method of fabrication, the flip-chip assembly technique leverages the existing industry and is far more efficient and realizable. Highly complex structures and integrated microsystems can be made by flip-clip bonding surface-micromachined features onto a variety of other work surfaces like ceramic substrates, CMOS control chips or even other MEMS chips fabricated in the same process. The original silicon host substrate is them removed during the release etch to produce highly advanced systems that are better suited to RF, microwave, or optical applications where specific material properties, additional layers or control electronics are required.