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Background: I'm a statistician working with a design of experiments example regarding plasma etching of circuits, and unfortunately, the author does not define what is meant by the units used for the etch rate ($\mathring{A}$/min). A google search has proved fruitless due to the specialized symbol and the fact that other texts also assume you already know what the $\mathring{A}$ symbol means (which is probably true for those who work in this field, but not for the rest of us).

Question: What does the $\mathring{A}$ unit mean in a plasma etching experiment, for "Etch rate ($\mathring{A}$/min)."

hazzey
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Meg
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    $\AA$ is the symbol for an Angstrom, $10^-10$ meters. – Carlton Feb 06 '16 at 15:13
  • For the record, the best way to render this symbol here might be with [the Unicode character](http://www.fileformat.info/info/unicode/char/212b/index.htm) (i.e., `$\unicode{x212b}$` --> $\unicode{x212b}$) since there's [an open issue describing the inability of MathJax to render `\AA`.](https://github.com/mathjax/MathJax/issues/795) That said, it makes sense to leave the question as it is in case people use "mathring" in a search query. – Air Feb 11 '16 at 18:25

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Anisotropic etching is a linear process, like welding, so presumably the units would be distance per time. Unlike welding it is at a small scale. See this slideshare. In this case units are Angstroms per minute. One Angstrom is $10^{-10}\ \textrm{m}$, indicating the process is on an atomic scale. Since it appears to be used for integrated circuit fabrication, those units are sensible depending on the scale.

do-the-thing-please
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