Thin Films - Functional Materials
The miniaturisation brought about by the scaling associated with the silicon semiconductor industry has been mirrored by the reduction in length scales for ferroelectric and other functional materials. This is especially apparent in MEMs devices. Today, significant barriers present obstacles to the development of new or improved materials and devices and to a large part are related to measurement confidence. Work at NPL will bridge some of these industrial and market failures, by addressing some of the major metrology issues pertinent to functional thin films.
Functional, particularly ferroelectric, thin films have recently been highlighted in an international study as being very important over the next five years in a number of applications, including microactuators and micromotors (Micro-Electro-Mechanical Systems, MEMS), capacitors and other thin film devices. Integrated dielectric devices and packages were considered very important for use in high frequency communications systems. The world wide research activity in ferroelectric thin films has historically been focused on those films having application within the semiconductor memory markets. The great interest for Gbit scale FE-RAMS (FerroElectric Random Access Memories) has been fuelled by their non-volatile operation and low voltage requirements, as well as their exciting potential for large scale integration and CMOS compatibility. A tremendous amount of work has been carried out in the development of these materials, notably by those countries that have the core semiconductor processing capabilities, such as USA, Japan, Korea.
Functional thin films are being used and are under development for use in a diverse range of applications including: accelerometers (air bag devices); force sensors; vibration, thickness and chemical sensors as well as biosensors; MEMS applications such as piezo microactuators and sensors; very small scale micro-reaction vessels for chemical and biological (lab on a chip) sensing; ferroelectric memories; electro-optical devices for military and civil thermal imaging based on the pyroelectric effect, shutters, optical switches, optical computation, information storage; ferroelectric thin film capacitors for integration with Si-CMOS process architectures (based in recent times on Relaxor technologies); strain generation from the functional (piezoelectric) properties of the thin films for microscale movements, micropump actuation, micromotors etc.; amplification structures based on functional thin films have been proposed; display technologies; pressure mats (piezoelectric thin film); Surface Acoustic Wave (SAW) devices for high frequency telecommunications filtering; embedded structures based on thin film technology for Smart Systems, active and adaptive structures (vibration control, etc.), and more.
For more information, please contact Mark Stewart