Etching method
An etching method for etching a silicon oxide film is provided that includes generating a plasma from a gas including a hydrogen-containing gas and a fluorine-containing gas using a high frequency power for plasma generation, and etching the silicon oxide film using the generated plasma. The fluorine-containing gas includes a hydrofluorocarbon gas, and the sticking coefficient of radicals generated from the hydrofluorocarbon gas is higher than the sticking coefficient of radicals generated from carbon tetrafluoride (CF 4 ).
1. An etching method for etching a silicon oxide film, the etching method comprising:
generating a first plasma from a gas including hydrogen (H 2 ) gas, carbon tetrafluoride (CF 4 ) gas, and a hydrofluorocarbon-containing gas that includes at least one of difluoromethane (CH 2 F 2 ) gas, monofluoromethane (CH 3 F) gas, or fluoroform (CHF 3 ) gas using a first high frequency power;
etching the silicon oxide film using the generated first plasma;
generating a second plasma from a gas consisting of hydrogen (H 2 ) gas and carbon tetrafluoride (CF 4 ) gas using a second high frequency power; and
etching the silicon oxide film using the generated second plasma, wherein
the etching with the first plasma is performed in a low temperature environment in which a temperature of a wafer is less than or equal to −35° C.,
the silicon oxide film is alternately etched with the first plasma and the second plasma,
reaction products generated from the carbon tetrafluoride (CF 4 ) and reaction products generated from the hydrofluorocarbon-containing gas are deposited on a side wall face of a hole, the reaction products generated from the carbon tetrafluoride (CF 4 ) being deposited at a greater depth within the hole than the reaction products generated from the hydrofluorocarbon-containing gas, and
the reaction products generated from the hydrofluorocarbon-containing gas are deposited over the deposited reaction products generated from the carbon tetrafluoride (CF 4 ), to thereby adjust an opening size of the hole.
2. The etching method according to claim 1 , wherein
the silicon oxide film is etched via a mask film; and
when the mask film comprises tungsten (W), a mask selectivity is greater than or equal to 10.
3. The etching method according to claim 1 , wherein
the silicon oxide film is etched via a mask film; and
when the mask film comprises polysilicon, a mask selectivity is greater than or equal to 5.
4. The etching method according to claim 1 , the method further comprising:
controlling the respective flow rates of the hydrofluorocarbon-containing gas to adjust the profile of reaction products deposited on a mask, wherein
the hydrofluorocarbon-containing gas includes two or more of difluoromethane (CH 2 F 2 ) gas, monofluoromethane (CH 3 F) gas, or fluoroform (CHF 3 ) gas.
5. The etching method according to claim 1 , wherein the temperature of the wafer is approximately −35° C.
6. An etching method for etching a silicon-containing film through an opening in a mask, the method comprising:
generating a plasma from a gas including hydrogen (H 2 ) gas, carbon tetrafluoride (CF 4 ) gas, and a hydrofluorocarbon-containing gas that includes difluoromethane (CH 2 F 2 ) gas, monofluoromethane (CH 3 F) gas, or fluoroform (CHF 3 ) gas using a high frequency power;
adjusting a profile of the opening in the mask, by controlling a flow rate of the CF 4 gas and of the hydrofluorocarbon-containing gas, to control position where reaction product is deposited; and
etching the silicon-containing film using the plasma through the opening in the mask, wherein
reaction products generated from the carbon tetrafluoride (CF 4 ) and reaction products generated from the hydrofluorocarbon-containing gas are deposited on a side wall face of the opening, the reaction products generated from the carbon tetrafluoride (CF 4 ) being deposited at a greater depth within the opening than the reaction products generated from the hydrofluorocarbon-containing gas, and
the reaction products generated from the hydrofluorocarbon-containing gas are deposited over the deposited reaction products generated from the carbon tetrafluoride (CF 4 ), to thereby adjust dimensions of the opening.
7. The etching method of claim 6 , wherein
the etching with the plasma is performed on a wafer having a temperature of less than or equal to −35° C.
8. The etching method of claim 7 , wherein
the silicon-containing film is a silicon oxide film.
9. The etching method of claim 6 , wherein
the mask includes polysilicon or tungsten.
10. The etching method of claim 6 , wherein
the generating of the plasma, the adjusting of the profile of the opening, and the etching of the silicon-containing film are performed simultaneously.
11. The etching method of claim 6 , wherein
a mask selectivity is greater than or equals to 10.
12. The etching method of claim 6 , wherein
the profile of the opening in the mask is adjusted by narrowing the opening.
13. The etching method of claim 7 , wherein
the first high frequency power is applied to the mounting table in generating the first plasma,
a second frequency of the second high frequency power is a lower frequency than a first frequency of the first high frequency power, and
the second high frequency power is output in the form of a pulse wave.
14. The etching method of claim 13 , wherein the first high frequency power is output in the form of a pulse wave.
15. The etching method of claim 13 , wherein the first high frequency power is output in the form of a continuous wave.