diff --git a/process_chemistry/chemistry_etching.tex b/process_chemistry/chemistry_etching.tex
index 9a0d7c2..2dcd6ea 100644
--- a/process_chemistry/chemistry_etching.tex
+++ b/process_chemistry/chemistry_etching.tex
@@ -8,7 +8,7 @@ \section{Etching silicon dioxide}
 \end{itemize}
 This can be prepared, for example, by mixing 113 g of $NH_4F$ in 170 ml of $H_2O$, and adding 28 ml of HF.\\
 The etch rate at room temperature can range from 1000 to 2500 \r{A}/min (100-250nm/min).
-This depends on the actual density of the oxide which, as an amorphous layer, can have a more compact structure (if thermally grown in is oxygen) or less compact (if grown by CVD).
+This depends on the actual density of the oxide which, as an amorphous layer, can have a more compact structure (if thermally grown in oxygen) or less compact (if grown by CVD).
 The following etching reaction holds:
 \begin{equation}
 	SiO_2 + 6HF \rightarrow H_2SiF_6 + H_2O