Chemical Processing With Lasers

Laser Processing and Chemistry gives an overview of the fundamentals and applications of laser-matter interactions, in particular with regard to laser material processing. Special attention is given to laser-induced physical and chemical processes at gas-solid, liquid-solid, and solid-solid interfaces. Starting with the background physics, the book proceeds to examine applications of laser techniques in micro-machining, and the patterning, coating, and modification of material surfaces. This fourth edition has been revised and enlarged to cover new topics such as 3D microfabrication, advances in nanotechnology, ultrafast laser technology and laser chemical processing (LCP). Graduate students, physicists, chemists, engineers, and manufacturers alike will find this book an invaluable reference work on laser processing.

It has often been said that the laser is a solution searching for a problem. The rapid development of laser technology over the past dozen years has led to the availability of reliable, industrially rated laser sources with a wide variety of output characteristics. This, in turn, has resulted in new laser applications as the laser becomes a familiar processing and analytical tool. The field of materials science, in particular, has become a fertile one for new laser applications. Laser annealing, alloying, cladding, and heat treating were all but unknown 10 years ago. Today, each is a separate, dynamic field of research activity with many of the early laboratory experiments resulting in the development of new industrial processing techniques using laser technology. Ten years ago, chemical processing was in its infancy awaiting, primarily, the development of reliable tunable laser sources. Now, with tunability over the entire spectrum from the vacuum ultraviolet to the far infrared, photo chemistry is undergoing revolutionary changes with several proven and many promising commercial laser processing operations as the result. The ability of laser sources to project a probing beam of light into remote or hostile environments has led to the development of a wide variety of new analytical techniques in environmental and laboratory analysis. Many of these are reviewed in this book.

The possibility of initiating chemical reactions by high-intensity laser exci tation has captured the imagination of chemists and physicists as well as of industrial scientists and the scientifically informed public in general ever since the laser first became available. Initially, great hopes were held that laser-induced chemistry would revolutionize synthetic chemistry, making possible "bond-specific" or "mode-specific" reactions that were impos sible to achieve under thermal equilibrium conditions. Indeed, some of the early work in this area, typically employing high-power continuous-wave sources, was interpreted in just this way. With further investigation, however, a more conservative picture has emerged, with the laser taking its place as one of a number of available methods for initiation of high-energy chemical transformations. Unlike a number of these methods, such as flash photolysis, shock tubes, and electron-beam radiolysis, the laser is capable of a high degree of spatial and molecular localization of deposited energy, which in turn is reflected in such applications as isotope enrichment or localized surface treatments. The use of lasers to initiate chemical processes has led to the discovery of several distinctly new molecular phenomena, foremost among which is that of multiple-photon excitation and dissociation of polyatomic molecules. This research area has received the greatest attention thus far and forms the focus of the present volume.

The high cost of laser energy is the crucial issue in any potential laser-processing application. It is expensive relative to other forms of energy and to most bulk chemicals. We show those factors that have previously frustrated attempts to find commercially viable laser-induced processes for the production of materials. Having identified the general criteria to be satisfied by an economically successful laser process and shown how these imply the laser-system requirements, we present a status report on the uranium laser isotope separation (LIS) program at the Lawrence Livermore National Laboratory (LLNL).

It has often been said that the laser is a solution searching for a problem. The rapid development of laser technology over the past dozen years has led to the availability of reliable, industrially rated laser sources with a wide variety of output characteristics. This, in turn, has resulted in new laser applications as the laser becomes a familiar processing and analytical tool. The field of materials science, in particular, has become a fertile one for new laser applications. Laser annealing, alloying, cladding, and heat treating were all but unknown 10 years ago. Today, each is a separate, dynamic field of research activity with many of the early laboratory experiments resulting in the development of new industrial processing techniques using laser technology. Ten years ago, chemical processing was in its infancy awaiting, primarily, the development of reliable tunable laser sources. Now, with tunability over the entire spectrum from the vacuum ultraviolet to the far infrared, photo chemistry is undergoing revolutionary changes with several proven and many promising commercial laser processing operations as the result. The ability of laser sources to project a probing beam of light into remote or hostile environments has led to the development of a wide variety of new analytical techniques in environmental and laboratory analysis. Many of these are reviewed in this book.

Nine expert contributors describe the application of laser processing techniques in the fabrication of semiconductor materials & devices for the microelectronics industry. This book comprises a carefully edited collection of specially written reviews by leading figures in all aspects of this important area of high technology. This subject matter should interest anyone involved with a semiconductor fabrication facility or a development laboratory with an interest in modern advances in processing technology, especially those people working in the larger electrical & electronics companies. In addition, it will be of value to university groups in engineering & physics departments involved in laser processing of materials, & of subsidiary interest to microfilm technologists working in optics fabrication.