Slow etching Insulator with HF

Hi,

I am looking for an insulator which has a much slower etch rate in HF than SiOx. It would be important, that it could be grown either by thermal evaporation or sputter deposition on top of Si0x. Does such a material exist?

Also, does anyone know a good reference where etch rates of materials are listed?

Last question: What happens to Cu and Co in HF?

Thanks a lot!

Barbaros

Beeswax can be deposited from vapor, and it resists HF.

Hi Mark,

I am also worried about outgasing in UHV; do you have perhaps a reference on how beeswax is evaporated?

Thanks

Barbaros

Silicon nitride is a good candidate. While deglassivating ICs, I would remove the silicon dioxide with a buffered HF solution. Then I would have to remove the silicon nitride with a plasma etcher.

Al

A mixture of beeswax and rosin was used as a sealant in 19th and early 20th century vacuum systems, so I don't think it would outgas at room temperature.

Simple heating should evaporate it, as in a candle. Though I can't guarantee there won't be some thermal degradation. Beeswax molecules are long chains, which may be difficult to volatilize without some decomposition.

Rosin is also resistant to HF, as it is used in some formulations of resist for glass etching. Rosin for sure can be volatilized cleanly. That might be another candidate for your resist layer.

What about silicon nitride? You can sputter silicon in a nirtogen ambient. And then there is aluminum oxide, similarly can be reactively sputtered. Both have low etch rates in HF, but alumina is tough to etch in anything, so is hard to pattern.

Cu survives in HF as well as most non-oxidizing acids. It is a fairly nobel metal. Co I dont know about.

Get a copy of Thin Film Technology by Vossen and Kern. It has an etching table.

-J

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