The Foundations of Vacuum Coating Technology

Donald M. Mattox

• Publisher: William Andrew
• Year: 2018
• Edition: 2
• eBook ISBN:
  9780128130858
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

The Foundations of Vacuum Coating Technology, Second Edition, is a revised and expanded version of the first edition, which was published in 2003. The book reviews the histories of the various vacuum coating technologies and expands on the history of the enabling technologies of vacuum technology, plasma technology, power supplies, and low-pressure plasma-enhanced chemical vapor deposition. The melding of these technologies has resulted in new processes and products that have greatly expanded the application of vacuum coatings for use in our everyday lives. The book is unique in that it makes extensive reference to the patent literature (mostly US) and how it relates to the history of vacuum coating. The book includes a Historical Timeline of Vacuum Coating Technology and a Historical Timeline of Vacuum/Plasma Technology, as well as a Glossary of Terms used in the vacuum coating and surface engineering industries. - History and detailed descriptions of Vacuum Deposition Technologies - Review of Enabling Technologies and their importance to current applications - Extensively referenced text - Patents are referenced as part of the history - Historical Timelines for Vacuum Coating Technology and Vacuum/Plasma Technology - Glossary of Terms for vacuum coating

Chapter 1

About This Book

Abstract

This work is meant to portray the historical aspects of the subject of vacuum coating rather than the more contemporary aspects. This chapter discusses the details of what is covered and what is not covered. The book is unique in that it references a great deal of patent literature. The types of references used are discussed and examples provided as to how they affect history. History is in the eyes of the author so it is not expected that everyone will agree as to the weight that is given to each subject particularly patents. From the Preface of the first edition:

Those that do not know the history of their field are doomed to repeat its mistakes or end up in patent litigation.

G. Santayana, paraphrased

Keywords

History; terminology; source of references

Introduction

This work portrays the subject of vacuum coating from an historical perspective. For more contemporary aspects the reader is referred to more recent journals, proceedings, and books dedicated to the subject of interest.

Vacuum coating has evolved as an important industrial process in the past 65 years. In the last 50 years vacuum coating has allowed numerous new applications to be developed. Vacuum coating is normally associated with vaporization from a solid or liquid surface. However, it should be recognized that the use of chemical vapor precursors such as hydrocarbon compounds has become more important as a condensing vapor source in hybrid vacuum deposition processes, using both vaporization of a solid/liquid along with the decomposition of the chemical vapor precursor.

The advancements in the enabling technologies of vacuum technology (Chapter 2: Vacuum Technology), together with advancements in plasma technology and electrical power supplies (Chapter 3: Plasmas and Plasma Enhanced CVD) are discussed. Appendix 1 provides an historical timeline of both vacuum deposition and vacuum and plasma technology. Other enabling technologies of surface preparation [1–3] and processing environments such as “clean rooms” [4,5] will not be discussed. It should be noted that the successful production of a product not only depends on the deposition process but upon all aspects of the process flow from the incoming material to the final packaging. Fig. 1.1 shows a “flowchart” that not only shows the processing flow but also the decisions about vacuum equipment and processing that must be made during the development phase (also see Ref. [6]). The reproducibility of the process depends on controlling the process parameters within the parameter “windows.”

Figure 1.1 Flowchart of the vacuum coating processing sequence. This chart includes the equipment and process decisions that are relevant to developing a vacuum coating process. <http://www.mpinm.com> Process Flow diagram for PVD processing [6].

Terminology

Vacuum Deposition–Vacuum Coating–Physical Vapor Deposition–Chemical Vapor Deposition

Vacuum deposition is accomplished by vaporizing a solid or liquid in “good vacuum” such that the vapor deposits as atoms or molecules on the surface to be coated. If vaporization does not take place in a good vacuum the vapors condense in the vapor phase by multibody collisions to form particulates (soot). The term Physical Vapor Deposition (PVD) was first used in 1955 by C.F. Powell et al. in the book Vapor-Plating: The Formation of Coatings by Vapor-Deposition Techniques to differentiate PVD from Chemical Vapor Deposition (CVD) [7]. In PVD the vaporization is from a solid or liquid surface. CVD is when the material to be deposited comes from a chemical vapor precursor. If a plasma is used to aid the CVD process it is called plasma-enhanced CVD (PECVD) or in some cases “plasma deposition.” The rational for this PVD/CVD distinction was discussed in the Preface of the 1966 book Vapor Deposition edited by C.F. Powell et al. [8]. The term PVD was not widely used until the 1990s but instead the process was more generally called “Vacuum Deposition” (e.g., Ref. [9]).

The term “vacuum coating” covers both PVD and low-pressure CVD such as PECVD. The hybrid vacuum coating process of PVD and PECVD (PVD/PECVD) began to be developed and applied to products in the early 1970s with the introduction of the “ion plating” process where “plasma activation” of CVD precursors takes place at low pressures (Chapter 3: Plasmas and Plasma Enhanced CVD). By having ion bombardment during deposition the substrate surface may directly heated. Activation and heating both promote chemical reactions on the surface (Chapter 7: Ion Plating).

“Thin Film” Versus “Coating”

The literature on vacuum deposition uses the terms “thin film” and “coating” often without any definition. Early uses of vacuum coatings were for reflecting surfaces and antireflection films, both of which only require film thicknesses on the order of a quarter of the wavelength of visible light or about 1500 Å (150 nm), so it seems logical to call these film thicknesses “thin” films. As the vacuum deposits became thicker, for tribological purposes for instance, it would have been logical to call them “thick” films but that terminology has a specific meaning in hybrid microelectronic technology [10]. Therefore the term “vacuum coating” seemed to be a good compromise.

Units of Pressure

There are different units for the pressure in a vacuum environment used in different countries and in different disciplines. The most common system of units are the centimeter-gram-second (CGS), the meter-kilogram-second (mks), the foot-pound-second (fps), and the “customary system” of units. In the United States a customary system of units (pounds per square inch—psi and inches Hg—inHg {aeronautical}) are generally used, though the US Metric Conversion Act was passed in 1975 which was supposed to encourage changing to the metric system. Among scientists the International Standard (SI) units are used and some journals will not accept any other unit system in their papers. The SI system has basic units such as the meter (m), kilogram (kg), second (s), Ampere (A), and Kelvin temperature (K) and derived units such as Newton (N) for force, Joule (J) for heat, and Pascal (Pa) for pressure.

The first units used for pressure was millimeters of mercury (mmHg) which became 1 mmHg=1 Torr, named after Torricelli. In vacuum technology the use of milliTorr (1/1000 of a Torr) (0.133 Pa) is often used and in some literature 1/1000 mmHg is called a “micron.”

The International Standard Atmosphere (ISO) is taken to be 101,325 Pa (1.01325 bar; 14.6959 psi; 29.92 inchesHg; 760 mmHg) at 15°C. The common units of pressure in meteorology are the millibar (mb), and the hectopascal (hPa).¹

Text References

This work is meant to be more historical than contemporary though many contemporary references are provided along with the historical references. The author has striven to give the earliest references to a particular subject. The source of references may be divided into the categories of: (1) books and book chapters, (2) periodic journals and transactions, (3) proceedings of conferences and meetings, (4) patents, (5) documents, such as reports and magazines, (6) the Internet (Blogs, YouTube, etc.), and (7) others, such as oral histories and private communications.

Books and Book Chapters

Book references were the earliest references for vacuum technology. Often early books were published by the author to disseminate their work since few scientific journals were available in the 16th and 17th century. Today very few technical books have single authors but are rather collections of chapters written by different authors who have expertise in the subject being covered in that chapter. Portions of early books or the whole book are often available on the Internet (e.g., Google Books) [11].

Periodic Journals and Transaction Articles

Articles in periodic journals may or may not be “peer-reviewed.” Emphasis on peer reviewing and “refereeing” of articles for journals has mostly developed since the 1950s [12,13]. The use of the title transaction for a group of articles was and sometimes is used the way proceedings is often used today. Often transactions are not peer-reviewed.

In 1660 King Charles II founded the Royal Society of London in England to promote the theory and application of science. In 1662 the newly formed “Royal Society of London for Improving Natural Knowledge” was granted a charter to publish by King Charles II and on March 6, 1665, the first issue of Philosophical Transactions was published under the editorship of Henry Oldenburg, who was also the Secretary of the Society. The first volumes of what was the world’s first scientific journal were very different from today’s journal, but in essence it served the same function; namely, to inform the Fellows of the Society and other interested readers of the latest scientific discoveries. As such, Philosophical Transactions established the important principles of scientific priority and peer review, which have become the central foundations of scientific journals ever since. In 1886 the breadth and scope of scientific discovery had increased to such an extent that it became necessary to divide the journal into two, Philosophical Transactions A and B, covering the physical sciences and the life sciences, respectively.

The first scientific society, in what became the United States, was the American Philosophical Society, which was founded in 1743 under the leadership of Benjamin Franklin. The Transactions of the American Philosophical Society began publication in 1771. Up to that time most American scientists published in European journals. In 1819 Benjamin Silliman, who has been called the “father of American scientific education,” started publishing the American Journal of Science and Arts (AJSA). The AJSA is the oldest journal still published in the United States and is now known as the American Journal of Science and publishes mainly on geology. The term “arts” was used for what we now call “technology” well into the 20th century and the term is still used in the patent literature.

Many early papers on vacuum coating were published in the Journal of the Electrochemical Society (JES), which began in 1853. The Journal of the Optical Society of America (JOSA) began publishing in 1917. The journal Vacuum began publishing in January 1951 in England. The American Vacuum Society (AVS) was formed in 1953 to provide a forum for those interested in the scientific and industrial development of vacuum equipment and processes in the United Sta...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Biography
• Foreword
• Preface
• Acknowledgments
• Chapter 1. About This Book
• Chapter 2. Vacuum Technology
• Chapter 3. Plasmas and Plasma Enhanced CVD
• Chapter 4. Physical Sputtering and Sputter Deposition
• Chapter 5. Thermal Evaporation and Deposition in Vacuum
• Chapter 6. Cathodic Arc Vaporization and Cathodic Arc Vapor Deposition
• Chapter 7. Ion Plating
• Chapter 8. Condensation, Nucleation, Interface Formation, and Film Growth
• Appendix I. Historical Timeline
• Appendix II. Glossary of Terms Used in Vacuum Coating
• Index