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 including a first high-frequency power supply and a second high-frequency power supply, the etching method comprising:
a first process of causing the first high-frequency power supply to output a first high-frequency power with a first frequency and causing the 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 a 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, 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 output of the first high-frequency power supply is also stopped in synchronization with the stopping of the output of the second high-frequency power supply.
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. An etching method performed by an etching apparatus including a first high-frequency power supply and a second high-frequency power supply, the etching method comprising:
causing the first high-frequency power supply to output a first high-frequency power with a first frequency and causing the 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 a 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, at least one of the first high-frequency power and the second high-frequency power being a pulse wave; and
controlling a duty ratio of the pulse wave.
6. The etching method as claimed in claim 5 , wherein the duty ratio is less than or equal to 50%.
7. The etching method as claimed in claim 6 , wherein
both of the first high-frequency power and the second high-frequency power are pulse waves; and
the duty ratio of the first high-frequency power is the same as the duty ratio of the second high-frequency power.
8. The etching method as claimed in claim 5 , wherein
both of the first high-frequency power and the second high-frequency power are pulse waves;
the duty ratio of the first high-frequency power and the duty ratio of the second high-frequency power are controlled; and
the output of the first high-frequency power supply is reduced in synchronization with stopping of the output of the second high-frequency power supply.
9. The etching method as claimed in claim 5 , wherein the hydrogen-containing gas is a hydrogen (H 2 ) gas and the fluorine-containing gas is a carbon tetrafluoride (CF 4 ) gas.
10. An etching method performed by an etching apparatus including a first high-frequency power supply and a second high-frequency power supply, the etching method comprising:
a first process of causing the first high-frequency power supply to output a first high-frequency power with a first frequency and causing the 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 a 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 and reducing the output of the first high-frequency power supply in synchronization with the stopping of the output of the second high-frequency power supply, wherein
the first process and the second process are repeated multiple times; and
the first process is shorter in time than the second process.
11. The etching method as claimed in claim 10 , wherein a duration of the first process is less than or equal to one third of a duration of the second process.
12. The etching method as claimed in claim 10 , wherein the hydrogen-containing gas is a hydrogen (H 2 ) gas and the fluorine-containing gas is a carbon tetrafluoride (CF 4 ) gas.