Etching method
View Patent ↗An etching method etches an organic film by using an inorganic film as a mask at a high etch rate, in a satisfactory etch profile in a satisfactory in-plane uniformity without causing the inorganic film to peel off. An organic film formed on a workpiece is etched by using an inorganic film as a mask with a plasma produced by discharging an etching gas in a processing vessel ( 1 ). The etching method uses a mixed gas containing NH 3 gas and O 2 gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio of 40% or above. The etching method uses NH 3 gas as an etching gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio below 40%.
1. An etching method comprising:
using an inorganic film as a mask for etching an organic film formed on a workpiece with a plasma of an etching gas in a processing vessel,
using a mixed gas containing NH 3 gas and O 2 gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio of 40% or above, and
using NH 3 gas without O 2 gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio below 40%.
2. The etching method according to claim 1 , wherein a support device supporting the workpiece is maintained at a temperature in the range of 40 to 80° C. when the organic film is to be etched in a pattern having an opening ratio of 40% or above, and is maintained at a temperature in the range of −20 to 40° C. when the organic film is to be etched in a pattern having an opening ratio below 40%.
3. The etching method according to claim 1 , wherein patterns having an opening ratio of 40% or above are line-and-space patterns, and patterns having an opening ratio below 40% are perforated patterns.
4. The etching method according to claim 1 , wherein an inorganic material forming the inorganic film contains silicon oxide as a principal component.
5. The etching method according to claim 1 , wherein the organic film is a low-K film.
6. The etching method according to claim 1 , wherein the workpiece is provided with a film to be etched underlying the organic film, and the film to be etched is etched by using the organic film as a mask.
7. The etching method according to claim 6 , wherein the film to be etched underlying the organic film is at least one of SiO 2 film, a SiON film, a SiN film, a SiOC film and a SiC film.
8. The etching method according to claim 1 , wherein the plasma is produced by a capacitively coupled plasma producing device that creates a high-frequency electric field between a pair of opposite electrodes.
9. The etching method according to claim 8 , wherein a magnetic field perpendicular to the electric field is created between the pair of opposite electrodes for etching.
10. An etching method using inorganic film as a mask for etching an organic film formed on a workpiece with a plasma of an etching gas in a processing vessel, said etching method characterized in that a mixed gas containing NH 3 gas and O 2 gas is used for etching the organic film when the organic film is to be etched in a pattern having an opening ratio of 40% or above, and HN 3 gas is used as an etching gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio below 40%,
wherein the etching gas is supplied so that the residence time of the etching gas is in the range of 4 to 10 msec when the organic film is to be etched in a pattern having an opening ratio of 40% or above, and the etching gas is supplied so that the residence time of the etching gas is 100 msec or below when the organic film is to be etched in a pattern having an opening ratio below 40%.
11. An etching method comprising:
using an inorganic film as a mask for etching an organic film formed on a workpiece with a plasma of an etching gas in a processing vessel,
using, in the same processing vessel, a first etching process with a mixed gas containing NH 3 gas and O 2 gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio of 40% or above, and
using, in the same processing vessel, a second etching process with NH 3 gas but without O 2 gas as an etching gas for etching the organic film when the organic film is to be etched in a pattern having an opening ratio below 40%.
12. The etching method according to claim 11 , wherein the temperature of a support device supporting the workpiece is in the range of 20 to 40° C. in the first and the second etching process.
13. The etching method according to claim 11 , wherein the NH 3 /O 2 flow rate ratio is determined so that the absolute value of CD shift is 6 nm or below when the organic film is to be etched in a patter having an opening ratio of 40% or above, and the residence time of NH 3 gas is determined so that the absolute value of CD shift is 6 nm or below when the organic film is to be etched in a pattern having an opening ratio below 40%.
14. The etching method according to claim 11 , wherein patterns having an opening ratio of 40% or above are line-and-space patterns, and patterns having an opening ratio below 40% are perforated patterns.
15. The etching method according to claim 11 , wherein the organic film is a low-K film.
16. The etching method according to claim 11 , wherein the workpiece is provided with a film to be etched underlying the organic film, and the film to be etched is etched by using the organic film as a mask.
17. The etching method according to claim 16 , wherein the film to be etched underlying the organic film is at least one of SiO 2 film, a SiON film, a SiN film, a SiOC film and a SiC film.
18. The etching method according to claim 11 , wherein the plasma is produced by a capacitively coupled plasma producing device that creates a high-frequency electric field between a pair of opposite electrodes.
19. The etching method according to claim 18 , wherein a magnetic field perpendicular to the electric field is created between the pair of opposite electrodes for etching.