ENGINEERING TRIPOS PART IIB - 2012/2013

Module 4M6 - Materials and Processes for Microsystems (MEMS)

AIMS

Microsystems (otherwise known as MicroElectroMechanical Systems, MEMS) are mechanical devices that are fabricated on a micrometre scale using techniques more commonly associated with the semiconductor industry for the fabrication of microelectronic devices. They can be classified as either passive devices (e.g. cantilevers, beams) or actuators (e.g. electrostatic drives, thermal expansion actuators) or sensors (e.g. gyroscopes, presure sensors) and the worldwide market for these devices has expanded greatly in recent years. This course will introduce both the processing methods by which these devices are manufactured and the properties of the materials which are employed, including traditional silicon-based technology and new materials, such as diamond-like carbon, polymers and biological thin films. Case studies will be used with particular reference to one sensing and one actuating application to exemplify how materials and fabrication processes are integrated. Those interested in taking this course might also be interested in 4C15 (MEMS Mechanical Design & Dynamic Performance).

More information can be found on the 4M6 website at http://www2.eng.cam.ac.uk/~ajf/4M6

LECTURE SYLLABUS

Introduction (1L)

• Overview of Microsystems technology and introduction of principal case studies

Materials and Growth (4L)

• Silcon-based materials
• Carbon-based materials
• Metals, TCOs and polymers

Materials Properties, Selection and Charcterisation (3L)

• Physical properties of thin films
• Materials selection
• Materials characterisation

Fabrication techniques (4L)

• Patterning
• Etching
• Bonding and planarisation and biomicrosystems
• Process flow
• Yield

COURSEWORK

One four hour lab session to fabricate and test a silicon nitrate cantilever. This will take place in the EDM Device Processing Clean Room. Students will be provided with a Si(100) wafer coated in silicon nitride. They will be expected to pattern the cantilever using photolithography, perform a dry RIE through the SiN layer, undercut the cantilever using a KOH etch and test the structure using a stylus profilometer.

OBJECTIVES

At the end of the module, students should:

• Appreciate the properties of a broad range of materials used in Microsystems.
• Be able to suggest suitable materials for given applications
• Understand a range of fabrication techniques applicable to the fabrication of micrometer scale structures and their limitations.
• Be able to design a process flow for the fabrication of a device.
• Be able to identify process steps that are likely to have the greatest impact upon yield.

REFERENCES

Please see the Booklist for Group R Courses for references for this module.

Last updated: June 2012