Specific Process Knowledge/Etch/Wet Polysilicon Etch: Difference between revisions
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The PolySi Etch is typically used for opening holes in poly-silicon thin-films, using photoresist as an etch mask or to strip Poly silicon of a wafer. Due to its isotropic nature the under-etching (etch-bias) at least amounts to the thickness of the poly-silicon layer. Another example of usage is etching of "circular-shaped" holes in silicon substrates. | The PolySi Etch is typically used for opening holes in poly-silicon thin-films, using photoresist as an etch mask or to strip Poly silicon of a wafer. Due to its isotropic nature the under-etching (etch-bias) at least amounts to the thickness of the poly-silicon layer. Another example of usage is etching of "circular-shaped" holes in silicon substrates. | ||
The PolySi Etch is based on the combined oxidation of silicon followed by dissolution of the silicon oxide. The etch solution consists of: | The PolySi Etch is based on the combined oxidation of silicon (by nitric acid) followed by dissolution of the silicon oxide (by hydrofluoric acid). The etch solution consists of: | ||
HNO<sub>3</sub> : BHF : H<sub>2</sub>O - (20 : 1 : 20) | HNO<sub>3</sub> : BHF : H<sub>2</sub>O - (20 : 1 : 20) | ||