Seminar on Embedded MEMS Modules for BiCMOS Process

Submitted to :Dr. R. NakkeeranAssociate ProfessorDept. of electronicsPondicherry university

Submitted by :Himanshu ranjan dasM.Tech (electronics)Pondicherry university

ABSTRACT

Different MEMS process techniques have been integrated to 0.25 μm BiCMOS process. First developed technique is Back-End-Off-Line (BEOL) integration. This technique was developed using standard metallization layers of BiCMOS process with an additional MEMS process steps. An RFMEMS capacitive switch was realized using BEOL embedded MEMS module. Back-side substrate etch method was developed as second MEMS integration technique. This technique is demonstrated by several high-Q passive components which can prevent from substrate losses. Additional MEMS modules were achieved by only adding few more lithography and etch steps. Fully embedded integration of these MEMS process techniques to a standard BiCMOS process will allow realizing single-chip mm-wave transceivers using cost-effective standard SiGe process and allows designer to operate higher frequencies with less losses.

What is MEMS?

Micro-Electro-Mechanical Systems, or MEMS, is a technology that in its most general form can be defined as miniaturized mechanical and electro-mechanical elements (i.e., devices and structures) that are made using the techniques of microfabrication. The critical physical dimensions of MEMS devices can vary from well below one micron on the lower end of the dimensional spectrum, all the way to several millimeters.

Note: MEMS are made up of components between 1 to 100 micrometres in size (i.e. 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micrometres (20 millionths of a metre) to a millimetre (i.e. 0.02 to 1.0 mm).

What Is bicmos ?

BiCMOS' is an evolved semiconductor technology that integrates two formerly separate semiconductor technologies - those of the bipolar junction transistor and the CMOS transistor - in a single integrated circuit device.

Advantages of bicmos

Bipolar junction transistors offer high speed.

High gain, and low output resistance, which are excellent properties for high-frequency analog amplifiers.

whereas CMOS technology offers high input resistance and is excellent for constructing simple, low-power logic gates.

Disadvantages

BiCMOS as a fabrication process is not currently as commercially viable for some applications, such as microprocessors, as with exclusively BJT or CMOS fabrication. Unfortunately, many of the advantages of CMOS fabrication, for example, do not transfer directly to BiCMOS fabrication.

An inherent difficulty arises from the fact that optimizing both the BJT and MOS components of the process is impossible without adding many extra fabrication steps and consequently increasing the process cost

Why bicmos……?

There is a growing interest in providing fully integrated solutions with the availability of the new applications such as 60 GHz for wireless personal area wireless network, the 77 GHz for adaptive cruise control radar and the 94 GHz for military radar applications. As the operating frequency of RFICs moves to mm-wave frequency range, it becomes difficult to achieve affordable Q-factors from on-chip passive components using conventional thin-film, planar IC processes.

MEMS processing techniques came up as an emerging technology for realizing high performance passive components at high frequencies. Several different MEMS processing techniques were developed and published.

In fact, the results of these works seem excellent but integration problem of these structures to high-frequency BiCMOS ICs came up due to packaging and handling of these structures.

Cont…….

Several integration methods were tried to integrateMEMS components into IC using hybrid, monolithic andpost-processing methods . Especially for mm-wavecircuits, developed integration methods are not adequate dueto the effects of parasitic components from integrationmethods. Figure. 1 summarizes the basic integration methodsof MEMS to BiCMOS silicon substrates.

Areas of work

Back End of Line (BEOL) Technology Integration.

Integration of MEMS switches into a standard CMOS or BiCMOS Back-end-of-Line (BEOL) is appearing to be the most promising one to enable the realization of fully integrated multi-band transceivers.

Integrating of RF mems using bicmos process.

packaging and handling of these structures.

SOFTWARE REQUIRED :

COMSOL.

COVENTOR.

MEMS+.

INTELLISUITE SOFTWARE.

comsol

Comsol multiphysics is a finite element analysis , solver and simulation software/package for various physics and engineering application,especially coupled phenomena or multi physics.

coventor

Coventor is a software predicting actual from virtual.

It provides predictive 3D modelling and simulation for advance micro and nano fabrication technologies.

It enables to simulate ,optimize the fabrication process and is a time consuming process

coventor

Successful MEMS suppliers verify all aspects of their designs with simulations before sending them to the fab. Successful MEMS suppliers use the CoventorWare® design and simulation platform.

Mems +

MEMS+® provides designers with a solution to this vexing challenge. MEMS+ is a different kind of FEA, based on a unique MEMS-specific library of high-order, parametric finite elements.

conclusion

We are convinced that in near future, there is a need for integrating MEMS processing techniques in order to develop the concept of Microsystems for mm-wave communications. Fully embedded integration of these MEMS process techniques to a standard BiCMOS process will allow realizing single-chip mm-wave transceivers using cost-effective standard SiGe process and allows designer to operate higher frequencies with less losses.

REFERENCE

Embedded MEMS Modules for BiCMOS Process ,Technische Universitat Berlin, HFT4, Einsteinufer 25, 10587, Berlin, Germany

Thank u....!