Luminous Chemical VaporDeposition and InterfaceEngineering

By Hirotsuga

Yasuda,

Marcel Dekker,

2005, hardcover,

819 pages, 53,

45 s, ISBN:0-8247-5788-2

Everybody working in the fields of

plasma chemistry has used H. Yasuda’s

book on ‘‘Plasma Polymerization’’

published in 1985 as a standard work.

Main content, besides some considera-

tions on gas-phase reaction in general,

are kinetic and mechanistic aspects of

plasma polymerization. The influence

of different operational parameters,

separately and in combination, on the

film properties of deposits have been

discussed in detail. The book ends up

with a summary on potential applica-

tions due to unique properties of the

plasma polymerized films.

Now, twenty years later, a new book

from H. Yasuda on ‘‘luminous chemi-

cal vapor deposition and interface

engineering’’ is published. The book

consists of 36 chapters divided in four

main parts. These parts are:

I. Fundamentals of LCVD

II. Operation of LCVD and LCVT

III. Fundamentals of Surface and

Interface

IV. Interface Engineering

Whilst the first two parts comprise the

content of the previous book completed

by discussion of some process set-ups.

Part III and IV are mainly dedicated

to application-related surface properties.

All four parts are combined to offer a so

called ‘‘system approach interface engi-

neering’’ (SAIE). This means the devel-

opment of a plasma based process has

to cover all the demands of application

from the beginning, as there are stability

under practical conditions, large area

treatment, continuous in-line capability,

uniform treatment, high conversion rate

of the precursor and low-maintenance

processes.

The reader is well advised to set up a

list of the used abbreviations together

with their meaning, otherwise he is

likely to get lost in a labyrinth of new,

often unusual definitions. LCVD and

LCVT for example mean luminous

chemical vapordeposition and luminous

chemical vapor treatment, respectively.

The first one is often used in this book as

a synonym for plasma polymerization,

the latter one for plasma treatment.

Physics of plasma deposition or treat-

ment systems are described in a rather

phenomenological manner. Thus, depo-

sition processes are correlated to the

different zones of the glow in the dis-

charge and visualized by series of pic-

tures. From these pictures andadditional

spectral data the author derived the con-

clusion that ‘‘ionization is not an accu-

rate picture of the step that creates the

luminous gas phase’’ where the main

reactions start which are responsible for

deposition processes. With this concept

Yasuda reinitiates the discussion which

he has finished in 1981 with his concept

of ‘‘atomic polymerization’’. The

question whether charged particles or

radicals are mainly responsible for the

polymerization is back, and Yasuda’s

answer today is: Dissociation processes

(creation of radicals) in the ‘‘onion’’-

layered structureof the ‘‘luminousglow’’

aremainly appearing in the cathode layer

and less in the ‘‘negative glow’’ (named

here ‘‘dissociation glow’’, DG, and ‘‘ion-

ization glow’’, IG, respectively). Thus

the DG is mainly responsible for the

deposition. This concept is demonstrated

by spectral data from different glow reg-

ions and their correlation to photographs

of the glow zones using deposition pro-

cesses based on trimethylsilane (TMS)

and TMS/oxygen in a DC discharge. In

consequence details on ions and their

influence are really rare in the new book.

The observations are derived for DC

discharges because in RF discharges the

dissociation processes might happen

predominately in the vicinity of the

electrodes but do not result in a clearly

visible cathodic glow.

The book at hand is a huge compila-

tion of experimental data, for example

the precursors cited above are also

polymerized using different frequencies

and results are compared for 40 kHz,

13.56 MHz and DC. Beside some new

aspects the influence of the controlling

variables (substrate temperature, power

input, flow, chemical structure of mono-

mers etc.) on the deposition mechanism

and kinetics, already discussed in the

older book, is recapitulated in the first

part of the new book. Due to the aim of

covering application demands a new

paragraph on dangling bonds (which

can destabilize thin films) is added.

Often publications lack in sufficient

data to correlate different parameters, but

here a large amount of data and spectra is

shown, for example in the paragraph on

‘‘reactor size’’. They are taken from

different positions in three tubular reac-

tors which differ only by the diameter of

the used glass tubes. Working with such

geometries, interpretation is not easy,

because the compared deposition rate

will vary almost continuously as well as

the composition of the film along the

tube. Discrepancies to be expected with

such set ups are therefore shortly dis-

cussed by Yasuda and an additional

chapter on flow pattern predominantly

seen in such tubular reactors demon-

strates this problem in detail. Thus this

very busyworkmight bear less relevance

for comparison or scaling of reactors

in general, and demonstrates well

that tubular reactors are of less interest

for application purposes where homo-

geneity in composition and film thick-

ness is necessary.

Looking at the data presented here

from several reactor configurations

(‘‘anode magnetron torch’’, different

tubular reactors and a tumbler reactor)

as well as for different working modes

(primary, secondary and pulsed dis-

charges) the interest is mainly focused

on the change inwettability. Therefore it

is obvious to spend some chapters on

this surface property in more detail. In

the third part of the book at least four

Plasma Process. Polym. 2006, 3, 636–637 � 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

636 DOI: 10.1002/ppap.200600079 Book Review

chapters aremainly dedicated to several

aspects of wettability. Surface compo-

sition and its dynamic change due to

thermodynamically driven rearrange-

ments in contact with different media

(air or water etc.) is stressed. Again a

large amount of experimental data

are stringed busily together and the

most common methods for the meas-

urement of surface tension are men-

tioned (the sessile drop and Wilhelmy

plate method). Due to the fact that wet-

ting is a complex problem and there-

fore different models may be applied

more or less taking thermodynamic,

friction, molecular- and hydrodynamic

aspects into account, the phenomeno-

logical approach of Yasuda is justified

here and is the reason for the amount

of experimental data. Whilst in other

publications often the hysteresis of con-

tact angle measurement (the difference

between advancing and receding con-

tact angle) is not mentioned, here it is

stressed in detail and different influ-

ences on static and dynamic contact

angle measurement are qualitatively

discussed. Thus many data shown in

diagrams are presented, where summa-

rizing these data in a table would be

more appropriate and much more con-

cise. But nevertheless this part is bub-

bling over with ideas. These chapters

are suitable to initiate an overdue and

for sure controversial discussion on this

topic.

The fourth part of the book is mainly

dedicated to application demands where

plasma processes may give an answer.

It starts with a chapter on corrosion

protection. There it is mentioned that

barrier layers for this purpose have to be

stable with time and against humidity

andother corrosion initiating agents.The

segmental mobility of polymers is

described and held responsible for

instabilities and breakdown, not only of

thewettability but also of barrier proper-

ties, for which an ‘‘imperturbable sur-

face’’ (rigid highly cross-linked layer) is

strongly desired.

Thus, there is some contradiction

between surface mobilities to be

taken into account for polymers and

which are described in the third part of

the book and the requirements for

protective layers. Therefore in a first

example of ‘‘system approach inter-

face engineering (SAIE)’’ a complex

assembly of different layers is needed

and mentioned to result in a corrosion

protection layer for aluminum. Toge-

ther with different corrosion tests and

electrochemical impedance measure-

ments this approach is evaluated.

Beside high cross-linking also good

adhesion is a main goal of ‘‘SAIE’’ to

get long-term stable protective layers.

Consequentially the initiation of corro-

sion at interfaces and delamination is

discussed. Furthermore attempts are

described for enhanced adhesion on

polyethylene and for paint on Parylene

C (a CVD-deposited chlorinated poly-

paraxylylene). Again many experimen-

tal data are given to demonstrate the

effect of different plasma treatments on

the enhancement of adhesion. In the

same manner related examples of appli-

cation are described like corrosion

protection of cold rolled steel and iron.

The book ends up with a chapters on

membrane treatment, mainly covering

the literature up to 1994andonLCVD in

Biomaterials. Finally a semi-quantita-

tive economical comparison of a depo-

sition by a plasma process versus layer-

by-layer coatings is added to show that

plasma processes may compete with

liquid based processes.

Trying to summarize all aspects of

plasma technology addressed byYasuda

in his new book on 800 pages must

remain by far incomplete especially if

more a compilation than a textbook is

presented.

Who should read this book?Although

the book covers many aspects related to

plasma treatment, students expecting a

textbook that will guide them step by

step through this very complex field of

activity will not be satisfied and will

lose the plot from time to time. But if

they know already the basics from

elsewhere and if they are looking more

for special surface treatments or meth-

ods to measure application-relevant

surface properties, then they will find

here helpful suggestions from the view

of an experienced polymer chemist.

Secondly, physicists will on one

hand miss models or known theory

behind the phenomenological appro-

ach or at least they will miss some

attempts to consider more physical as-

pects and, if they are experienced they

possibly will be confused by the new

definitions and abbreviations. These

colleagues may take offense at this

compendium what hopefully will sti-

mulate them to start a fruitful discus-

sion on this book, what possibly is

provoked by the author. Thus, if

colleagues do not expect a textbook

or basics in plasma physics they will

earn a lot of stimuli for new experi-

ments or to edge their tools.

For colleagues who plan to start

activities in the field of plasma chem-

istry the book will give a first impres-

sion about examinations already done

and have not to be repeated, or where

however additional aspects have to be

considered.

The book covers many chemical and

especially polymer chemistry related

topics as they are seldom compiled in a

book dealing with plasma chemistry.

Unfortunately it is mainly restricted

to the author’s own work. From 58 lite-

rature references considered since the

year 2000 there are 56 from the author

himself. That means the book is more

or less the life’s work of Yasuda and

shows up the intensive activity he has

developed since the early seventies in

(t) his area and for which he is well-

known in the community.

Christian Oehr

Stuttgart (Germany)

Book Review 637

Plasma Process. Polym. 2006, 3, 636–637 www.plasma-polymers.org � 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim