How to reliably get a ~5nm carbon coat thickness?

[AnneF]

Hi Everyone!

I've done enough EPMA work to be pretty good at getting a reliable 20nm carbon coat on samples. However, I'm now prepping to send my samples (1x1 cm pieces of thin sections) off for some nanoSIMS analysis, and that will require a carbon coat closer to 5 nm thick. The first time I used nanoSIMS, my samples had a 20 nm C coat, and it took hours for the tiny Cs+ beam to sputter through to the actual sample material. The lab tech recommended we try just 5 nm of carbon on this next run. I don't currently have access to a carbon coater with a digital thickness meter, so do any of you know how I could approximate 5 nm with brass disks or another method? The ones I have access to are both sputter coaters.

Thanks!

[Probeman]

Hi Everyone!

I've done enough EPMA work to be pretty good at getting a reliable 20nm carbon coat on samples. However, I'm now prepping to send my samples (1x1 cm pieces of thin sections) off for some nanoSIMS analysis, and that will require a carbon coat closer to 5 nm thick. The first time I used nanoSIMS, my samples had a 20 nm C coat, and it took hours for the tiny Cs+ beam to sputter through to the actual sample material. The lab tech recommended we try just 5 nm of carbon on this next run. I don't currently have access to a carbon coater with a digital thickness meter, so do any of you know how I could approximate 5 nm with brass disks or another method? The ones I have access to are both sputter coaters.

Thanks!

Hi Anne,
I don't think you can rely on the color on brass method for a reproducible 5 nm thickness, and if you don't have a quartz crystal thickness monitor your best bet might be using some sort of electrical conductivity or light transmission method. 

See the posts from Karsten Goemann and Ben Wade in this topic:

https://probesoftware.com/smf/index.php?topic=1252.msg8842#msg8842