The Road To Flexible Mems Integration
- PDF / 1,199,196 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 87 Downloads / 184 Views
1075-J05-01
The Road To Flexible Mems Integration Ann Witvrouw PT/IPSI, IMEC, Kapeldreef 75, Leuven, 3001, Belgium ABSTRACT This paper first discusses the reasons for choosing CMOS-MEMS integration, in particular integration by poly-SiGe processing above CMOS. Next the current state-of-the-art for polySiGe MEMS integration and the needs for the future will be addressed. Market trends are translated into two roadmaps for MEMS integration. The first roadmap is based on existing polySiGe deposition processes at 400 - 450 ºC. The second roadmap explores processing techniques to lower the thermal budget and widen the application field of MEMS integration by using processing techniques such as metal-induced crystallization, laser annealing or self-assembly.
INTRODUCTION Polycrystalline silicon-germanium (poly-SiGe) has already shown its potential for integrating MEMS and CMOS in a MEMS-last approach. Fully functioning integrated SiGe MEMS devices such as CMOS-integrated gyroscopes [29] and resonators [22] have been demonstrated. First the current state-of-the-art of the MEMS integration work using poly-SiGe is presented, highlighting the material developments that were needed to get flat and reliable working devices. Then this paper addresses the question of what is expected to be needed for MEMS integration in the near and far future. To answer this question, first market trends are analyzed and translated into needs for MEMS integration. Two main trends are seen: first the trend towards increased functionality/unit area and thus lower cost/device and second a trend towards lower thermal budgets. Both trends are translated into roadmaps for MEMS integration. The first roadmap is based on existing poly-SiGe deposition processes at 400 - 450 ºC. The second roadmap explores processing techniques to lower the thermal budget and widen the application field of MEMS integration. These processing techniques use tricks to lower the crystallization temperature such as metal-induced crystallization or laser annealing. Ultimately self-assembly techniques might be used to integrate MEMS on any type of substrate. Both roadmaps are illustrated with examples from ongoing developments.
INTEGRATION OF MEMS AND CMOS Integration of the MEMS device with the integrated circuit becomes increasingly important for compactness and performance reasons [1-4]. About half of the current MEMS market [31], however, still uses a hybrid approach (Figure 1). Such an approach is modular and, as a consequence, has a much shorter development time as compared to the monolithic approach. Also it allows for an independent optimization of the integrated circuit (IC) and the MEMS technology. On the other hand, the assembly and packaging cost is higher in comparison to the monolithic approach. Consequently, once volumes become high enough, the longer development time needed for the monolithic approach is most likely to be paid back by the reduced assembly
and packaging cost. Monolithic integration is also often chosen in cases where a lot of interconnections
Data Loading...
