Method for etching an SiO.sub.2 film
AssigneesTokyo Electron Limited, Yasuhiro Horiike
InventorKouhei Kawamura
Life of this patent
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Abstract
An NF.sub.3 /H.sub.2 mixture as a feed gas for an etchant for etching an SiO.sub.2 film on an silicon wafer is used with a 1 : 160 NF.sub.3 /H.sub.2 mixed ratio. The mixture is made into plasma, and activated species of fluorine, hydrogen and nitrogen are supplied downstream to allow the species to be adsorbed in and on the SiO.sub.2 film. The NF.sub.3 /H.sub.2 mixed ratio of the mixture is so set as not to effect the etching of the SiO.sub.2 film under a chemical action. Then the adsorbed activated species are irradiated with Ar low energy ions so that the activated species are excited and etch the SiO.sub.2 film. During etching, the semiconductor wafer is maintained to about -100.degree. C. Less damage is caused to the silicon wafer and etching can be made in a high selection ratio.
Claims11
A method for etching an SiO.sub.2 film on a semiconductor wafer, comprising:
- positioning the wafer in a process chamber;
- evacuating the process chamber to a vacuum state;
- supplying activated species of fluorine and hydrogen in a mixed form onto the wafer to allow the species to be adsorbed in and on the SiO.sub.2 film, a mixed ratio of the activated species being so set as not to effect etching of the SiO.sub.2 film under a chemical action;
- and
- irradiating the adsorbed activated species with low energy ions of inert gas atoms to excite the activated species and etching the SiO.sub.2 film.
A method for etching an SiO.sub.2 film on a semiconductor wafer, comprising the steps of:
- positioning the semiconductor wafer in a process chamber;
- evacuating the process chamber to a vacuum state;
- introducing into the process chamber a mixture of a first gas containing fluorine and second gas containing hydrogen;
- making the mixture into plasma of low energy in the process chamber;
- supplying activated species of fluorine and hydrogen in the plasma onto the wafer to allow the species to be adsorbed in and on the SiO.sub.2 film, a mixed ratio in the activated species being so set as not to effect etching of the SiO.sub.2 film under a chemical action;
- irradiating the adsorbed activated species with ions in the plasma to excite the activated species and etching the SiO.sub.2 film.
Dependencies are inferred from the claim text.