Etching method
An etching method performed by an etching apparatus includes a first process of causing a first high-frequency power supply to output a first high-frequency power with a first frequency and causing a second high-frequency power supply to output a second high-frequency power with a second frequency lower than the first frequency in a cryogenic environment where the temperature of a wafer is −35° C. or lower, to generate plasma from a hydrogen-containing gas and a fluorine-containing gas and to etch, with the plasma, a multi-layer film of silicon dioxide and silicon nitride and a single-layer film of silicon dioxide that are formed on the wafer; and a second process of stopping the output of the second high-frequency power supply. The first process and the second process are repeated multiple times, and the first process is shorter in time than the second process.
1. An etching method performed by an etching apparatus, the etching method comprising:
placing, on a mount table of the etching apparatus, a wafer that includes a multi-layer film including a first silicon-containing film and a second silicon-containing film different from the first silicon-containing film and a single-layer film including the first silicon-containing film;
setting a temperature of the wafer at −35° C. or lower;
supplying, by a first radio-frequency power supply of the etching apparatus, a first radio-frequency power with a first frequency to generate plasma from a hydrogen-containing gas and a fluorine-containing gas;
performing a first process of applying a second radio-frequency power with a second frequency lower than the first frequency to the mount table by a second radio-frequency power supply of the etching apparatus; and
performing a second process of stopping the application of the second radio-frequency power, wherein
the first process and the second process are repeated multiple times; and
the first process is shorter in time than the second process.
2. The etching method as claimed in claim 1 , wherein in the second process, the supply of the first radio-frequency power is also stopped in synchronization with the stopping of the application of the second radio-frequency power.
3. The etching method as claimed in claim 1 , wherein a duration of the first process is less than or equal to one third of a duration of the second process.
4. The etching method as claimed in claim 1 , wherein the hydrogen-containing gas is a hydrogen (H 2 ) gas and the fluorine-containing gas is a carbon tetrafluoride (CF 4 ) gas.
5. The etching method as claimed in claim 1 , wherein
the multi-layer film and the single-layer film are etched by the generated plasma; and
in the second process, the supply of the first radio-frequency power is reduced in synchronization with the stopping of the application of the second radio-frequency power.
6. An etching method performed by an etching apparatus, the etching method comprising:
placing, on a mount table of the etching apparatus, a wafer that includes a multi-layer film including a first silicon-containing film and a second silicon-containing film different from the first silicon-containing film and a single-layer film including the first silicon-containing film;
setting a temperature of the wafer at −35° C. or lower;
supplying, by a first radio-frequency power supply of the etching apparatus, a first radio-frequency power with a first frequency to generate plasma from a hydrogen-containing gas and a fluorine-containing gas;
applying a second radio-frequency power with a second frequency lower than the first frequency to the mount table by a second radio-frequency power supply of the etching apparatus, at least one of the first radio-frequency power and the second radio-frequency power being a pulse wave; and
controlling a duty ratio of the pulse wave.
7. The etching method as claimed in claim 6 , wherein the duty ratio is less than or equal to 50%.
8. The etching method as claimed in claim 7 , wherein
both of the first radio-frequency power and the second radio-frequency power are pulse waves; and
the duty ratio of the first radio-frequency power is the same as the duty ratio of the second radio-frequency power.
9. The etching method as claimed in claim 6 , wherein the hydrogen-containing gas is a hydrogen (H 2 ) gas and the fluorine-containing gas is a carbon tetrafluoride (CF 4 ) gas.
10. The etching method as claimed in claim 6 , wherein
the multi-layer film and the single-layer film are etched by the generated plasma; and
the supply of the first radio-frequency power is reduced in synchronization with stopping the application of the second radio-frequency power.
11. An etching method performed by an etching apparatus, the etching method comprising:
placing, on a mount table of the etching apparatus, a wafer that includes a multi-layer film including a first film and a second film different from the first film and a single-layer film including the first film;
outputting, by a first radio-frequency power supply of the etching apparatus, a first radio-frequency power with a first frequency to generate plasma from a process gas;
applying a second radio-frequency power with a second frequency lower than the first frequency to the mount table by a second radio-frequency power supply of the etching apparatus; and
stopping the application of the second radio-frequency power, wherein
the application of the second radio-frequency power to the mount table and the stopping of the application of the second radio-frequency power are repeated to concurrently etch the multi-layer film and the single-layer film.
12. The etching method as claimed in claim 11 , wherein a duration of the application of the second radio-frequency power to the mount table is shorter than a duration of the stopping of the application of the second radio-frequency power.