Fabrication challenges for next-generation devices: MEMS for rf wireless communications

With wireless communications becoming an important technology and growth engine for the semiconductor industry, many semiconductor companies are developing technologies that differentiate themselves in this space. One means of accomplishing this goal is to find a way to integrate passive components, which currently make up over 70% of the discrete components in a wireless handset today, directly on-chip thereby greatly simplifying handsets. While a number of technologies are being investigated to allow on-chip integration, microelectromechanical systems (MEMS) technologies are an important part of this development effort. They have been used to create switches, filters, local oscillators, variable capacitors and high quality factor inductors to name a few examples. The lithography requirements for these devices are very different than those found in standard semiconductor fabrication with the most important involving patterning over extreme topography. In this paper, we discuss some of the fabrication challenges for these devices as well as some approaches that have been demonstrated to satisfy them.