THIN FILM SCEINCE

Recent years, thin film science has grown world-wide into

a major research area. The importance of coatings and the

synthesis of new materials for industry have resulted in a

tremendous increase of innovative thin film processing technologies.

Currently, this development goes hand-in-hand

with the explosion of scientific and technological breakthroughs

in microelectronics, optics and nanotechnology

[1]. A second major field comprises process technologies for

films with thicknesses ranging from one to several microns.

These films are essential for a multitude of production areas,

such as thermal barrier coatings and wear protections,

enhancing service life of tools and to protect materials

against thermal and atmospheric influences . Presently,

rapidly changing needs for thin film materials and

devices are creating new opportunities for the development

of new processes, materials and technologies.

Therefore, basic research activities will be necessary in

the future, to increase knowledge, understanding, and to

develop predictive capabilities for relating fundamental

physical and chemical properties to the microstructure

and performance of thin films in various applications. In

basic research, special model systems are needed for quantitative

investigations of the relevant and fundamental processes

in thin film materials science. In particular, these

model systems enable the investigation of i.e. nucleation

and growth processes, solid state reactions, the thermal

and mechanical stability of thin film systems and phase

boundaries. Results of combined experimental and theoretical

investigations are a prerequisite for the development

of new thin film systems and the tailoring of their

microstructure and performance.

State of the Art

The major exploitation of thin film science is still in the

field of microelectronics. However, there are growing applications

in other areas like thin films for optical and magnetic

devices, electrochemistry, protective and decorative

coatings and catalysis. Most features of these thin film

activities are represented by a relatively new research area,

called surface engineering. Surface engineering has been

one of the most expanding scientific areas in the last 10

years and includes the design and processing of surface

layers and coatings, internal interfaces and their characterization.

Surface engineering is directed by the demands

of thin film and surface characteristics of materials.

(a) Thin film processing techniques

There exists a huge variety of thin film deposition processes

and technologies which originate from purely physical

or purely chemical processes. The more important thin

film processes are based on liquid phase chemical techniques,

gas phase chemical processes, glow discharge processes

and evaporation method. Recently, a considerable

number of novel processes that utilize a combination

of different processes have been developed. This combination

allows a more defined control and tailoring of the

microstructure and properties of thin films. Typical processes

are e.g. ion beam assisted deposition (IBAD) and

plasma enhanced CVD (PECVD). Examples for novel thin

film processing techniques, which are still under development,

are pulsed laser ablation (PLD) and chemical solution

deposition (CSD). Both techniques enable the synthesis

of complex thin film materials (complex oxides, carbides,

and nitrides).

Presently, experimental efforts are increasingly supported

by computational approaches that address complex growth

processes, saving time and money. These approaches

enable e.g. the description of the evolution of thin film

microstructures as a function of processing parameters.

(b) In situ characterization

The thin film process equipment can be categorized into

production equipment for device manufacturing, equipment

for research and development, and prototype apparatus

for fundamental investigations of new or established

deposition processes. One reason for the world-wide rapid

growth of deposition technology is that equipment manufacturers

have successfully met the demands for more

sophisticated deposition systems including in situ characterization

(e.g. reflection high-energy electron diffraction

(RHEED), scanning probe microscopy (SPM)) and process

monitoring techniques for measuring process parameters

and film properties (e. g. ellipsometry, plasma analysis

techniques). Novel experimental tools have enabled

discoveries of a variety of new phenomena at the nanoscale

which have in turn opened unexpected opportunities

for the development of thin film systems, and tremendous

progress regarding a fundamental understanding of the

respective technological processes has been made.

(c) New materials

Thin film systems necessitate direct control of materials

on the molecular and atomic scale, including surface modifications,

deposition and structuring. Many of these techniques

were improved during the last decade, resulting in

remarkable advances in the fundamental understanding

of the physics and chemistry of thin films, their microstructural

evolution and their properties. This progress has

led to the development of new materials, expanded applications

and new designs of devices and functional thin film

systems. One of the most outstanding examples is the successful

development of semiconductor devices with novel

materials like oxides and nitrides (e.g. GaN). Other typical

examples are advances in the synthesis of hard coatings

based on borides, carbides and nitrides.

Expectations 2000 –2010

The gap between solving fundamental materials problems

and developing new thin film devices for microelectronic

and nanotechnological applications is quickly increasing.

For example, in many applications the development of thin

film systems is accompanied by a variety of materials and

processing problems, which require extensive future

efforts to be solved. Prominent examples are the adhesion

and the thermal and environmental stability of thin film

systems. Future developments are critical to overcoming

obstacles to miniaturization as feature sizes in devices

reach the nanoscale. Basic research in this field will refer

to developments of experimental tools necessary to in situ

characterize and measure thin film structures (e.g. optical

and magnetic characterization), and developments of

novel techniques for synthesis and design. These techniques

may be more reliable, less expensive, or capable of

producing films with new or improved properties. Typical

examples are chemical solution deposition (CSD), including

hydrothermal approaches, biomimetic pathways for

assembling inorganic thin films, or device applications of

liquid crystalline polymer film.

Experiments alone will be insufficient. Theory and modelling

are essential for a complete understanding of the fundamental

growth and deposition processes. Multiscale

modelling of thin film and nanostructuring processes will

be an absolute necessity in the next decade in order to

utilize the tremendous potential of thin film science and

technology. It is expected that time consuming and expensive

experiments will be replaced by theory and modelling.

Especially, it is still necessary to develop a fundamental

understanding of the decisive growth and deposition processes.

It will be important for research institutes to focus

on the development of fundamental and novel processes

and devices. This will only be realized if a more defined

connection of the activities between single research

groups and industry can be achieved, based on a fluent

exchange of information. Research institutes and companies,

which cannot achieve this, will have difficulty competing

in future. In this field, Europe must compete directly

with the U.S. and Japan. In comparison to Europe,

there appears to exist an advantageous research environment

in the U.S. and Japan, which supports a more fluent

conversion of results from basic research into applications.

This could be balanced in Europe by improved

networking between industry and research laboratories in

the field of basic researc.

                  Morales R. Karelis

                     CI 1808995

                      ESS secc 2