5-13-99

Hi All,



This has possibly been covered so I'll apologise in advance.



Does anyone out there know of a method to accurately determine the thickness

of carbon films used on TEM grids? EELS is a possibility but I was looking

for a more direct measurement eg using an SPM.



Thanks very much.



Colin Veitch





Instrumentation Scientist

Electron Microscopy

Textile and Material Technology Group

CSIRO Textile and Fibre Technology

PO Box 21, BELMONT, Vic. 3216. Australia.



E-mail: colin.veitch@tft.csiro.au

Web: http://www.tft.csiro.au



Tel: +61 (0) 3 5246 4000

Fax: +61 (0) 3 5246 481

Hi. I was recently asked of a way to determine C film thickness. I remember

that using a polished brass specimen and observing the color is one way.

Does anyone have a source in the literature for this method? Thanks.

 

______________________

Roberto Garcia

Senior Analyst, Metallography

North Carolina State University

Analytical Instrumentation Facility

Box 7531, Room 303 EGRC

Raleigh, NC 27695-7531

rgarcia@unity.ncsu.com

http://spm.aif.ncsu.edu/aif

Roberto, We used a thin gold coating on the shiny side of household aluminum

foil. This works great for relative thicknesses. Russ

Gillmeister, Russ

RGillmeister@sdms.usa.xerox.com

Hallo Roberto,

In the first edition of "Electron Microprobe Analysis" of S.B.J. Reed

(Cambridge University Press 1975) you can find the next table.

for Carbon on polished brass

Thickness in nm Colour

15 Orange

20 Indigo red

25 Blue

30 Bluish green

35 Green blue

40 Pale green

45 Silver gold

We determined the thickness with our thin layer program and found out that

the values were very good.

The table is not found in newer editions of Reed's book.

Ir.Hans Heijligers

Solid State and Materials Chemistry Lab.

STO 2.45, Eindhoven University of Technology

POBox 513 NL-5600 MB Eindhoven

E-mail: H.J.M.Heijligers@TUE.NL

Tel.: +31 (0)402473051

Fax.: +31 (0)402445619

Glenn Poirier and Bernard Kestel (both messages appended)

advocate very accurate means of determining C film

thickness. No doubt these means have some applications.

However, for most applications it is rather more convenient

to determine thickness at the time of coating with fairly

good accuracy.

It is no use to an analyst to break the vacuum to determine

that another 3nm of carbon are required. For these reason

the polished brass slide method and the still more

convenient, auto-terminating thickness monitors are the

preferred means to determine coating thickness.

Incidentally, for WDS/EDS I used indigo red - 20nm; its

enough C to prevent charging on flat specimens and absorbs

fewer light X-rays.

Cheers

Jim Darley

ProSciTech Microscopy

PLUS

PO Box 111, Thuringowa QLD 4817 Australia

Phone +61 7 4774 0370 Fax: +61 7 4789 2313

Great microscopy catalogue, 500 Links, MSDS, User Notes

********************** www.proscitech.com.au *****

>

> If you have access to an AFM, accurate measurement of C

> thickness takes

> about 4 minutes.

> If I'm looking at flat samples, I use a toothpick to

> remove a thin line of

> carbon. I then can bring the sample to the AFM and

> directly measure the

> height of the step betwwen the sample and the top of the

> carbon film.

> Alternatively, if I can't work directly on the sample I

> coat a plain glass

> slide (making sure it is the same distance from the arc

as

> the sample) and

> measure the C thinckness on it.

> Hope this helps

>

> Glenn



> Glenn Poirier Tel: (514) 398 6774

> MicroAnalysis Laboratrory Fax: (514) 398 4680

> Earth and Planetary Sciences email: glennp@eps.mcgill.ca

> Rm. 238, 3450 University St.

> http://castaing.eps.mcgill.ca

> Montréal, Qc

> H3A 2A7

> Millennium hand and shrimp

When great accuracy of film thickness is not needed, we

simply place a small metal washer upon a glass slide near

the "specimen area".

after evaporation the step height between the shaded and

coated areas is measured optically on a bench interference

microscope. Ours is a Zeiss two beam unit that is good for

30 nanometer resolution, (+ or -), with no physical contact

with the film. It works for ANY reflective metallic film

and fairly well even on "dull" carbon coatings because it

has three different reference mirrors that can be quickly

changed. Each mirror has a different reflectivity that one

merely tests to get reasonable interference fringes which

can also be photographed via polaroid or 35 mm. film.

Bernie Kestel

Materials Science Division Argonne National Laboratory

Robert,

Try The American Mineralogist, Volume 58, pages 920-925, 1973.

The role of Carbon Film Thickness in Electron Microprobe

Analysis - Kerrick DM, Eminhizer LB amd Villaume JF.



Bob

RmacKay

rmackay@IS.Dal.Ca

[Return to Tips & Tricks Menu]