Method of fabricating semiconductor device
View Patent ↗Photoresist on a metal is removed with less oxidation of the metal surface by the invented ashing. During process, the matching of oxygen gas ratio and wafer temperature under downstream plasma which means no RF bias plasma is controlled for oxidation amount not to depend on ashing time with required photo resist rate in manufacturing.
1. A method of fabricating a semiconductor device, said method comprising:
forming a first metal film on a substrate;
forming a photoresist film on the first metal film;
forming a pattern in the photoresist film;
processing the first metal film by dry etching with the pattern as a mask;
ashing the photoresist without any bias at a predetermined temperature on the first metal film processed during the dry etching using a gas that comprises oxygen;
forming a dielectric film on the first metal film subjected to ashing of the photoresist; and
forming a second metal film on the dielectric film to form a metal-insulator-metal (MIM) capacitor,
wherein a percentage of oxygen gas for the ashing is not more than a percentage of oxygen where an oxidation amount of the first metal layer is independent of a duration of said ashing.
2. The method of fabricating a semiconductor device according to claim 1 , wherein the percentage of the oxygen gas is set to not less than a percentage that an ashing rate is 200 run/min or faster.
3. The method of fabricating a semiconductor device according to claim 1 , wherein the first metal film comprises a metal nitride film.
4. The method of fabricating a semiconductor device according to claim 1 , wherein the first metal film comprises titanium nitride.
5. The method of fabricating a semiconductor device according to claim 1 , wherein the predetermined temperature is not lower than 25° C. and not higher than 40° C.
6. The method of fabricating a semiconductor device according to claim 1 , wherein the predetermined temperature is 40° C. and the percentage of oxygen gas for the ashing is not less than 25% and not more than 50%.
7. The method of fabricating a semiconductor device according to claim 1 , wherein the predetermined temperature is 25° C. and the percentage of oxygen gas for the ashing is not less than 50% and not more than 80%.
8. The method of fabricating a semiconductor device according to claim 1 , wherein a thermal process is carried out between the ashing and the forming the dielectric film.
9. The method of fabricating a semiconductor device according to claim 8 , wherein the thermal process is carried out at not higher than 500° C.
10. The method of fabricating a semiconductor device according to claim 8 , wherein the thermal process is carried out in nitrogen.
11. The method of fabricating a semiconductor device according to claim 1 , wherein a thermal process is carried out between the forming of the first metal film and the forming of the photoresist film.
12. The method of fabricating a semiconductor device according to claim 1 , wherein a thermal process is carried out at least between one of the ashing and said forming of the dielectric film, and said forming of the first metal film and said forming of the photoresist film.
13. The method of fabricating a semiconductor device according to claim 1 , wherein the etching further comprises applying argon as a diluents gas.
14. The method of fabricating a semiconductor device according to claim 1 , further comprising:
setting the percentage of oxygen gas for the ashing based on a shape of the first metal film and a required capacitance value of the MIM capacitor.
15. The method of fabricating a semiconductor device according to claim 1 , further comprising:
adjusting a temperature of the ashing to set the percentage of oxygen gas for the ashing based on the percentage of oxygen where the oxidation amount of the first metal layer is independent of the duration of said ashing.
16. A method of fabricating a semiconductor device, said method comprising:
forming a first metal film on a substrate;
forming a photoresist film on the first metal film;
forming a pattern in the photoresist film;
processing the first metal film by dry etching with the pattern as a mask;
ashing the photoresist without any bias at a predetermined temperature on the first metal film processed during the dry etching;
forming a dielectric film on the first metal film subjected to ashing of the photoresist; and
forming a second metal film on the dielectric film to form a metal-insulator-metal (MIM) capacitor,
wherein a percentage of oxygen gas for the ashing is not more than a percentage of oxygen where an oxidation amount of the first metal layer is independent of a duration of said ashing, and
wherein a thermal process is carried out at least between one of the ashing and said forming the dielectric film, and said forming the first metal film and said forming the photoresist film.
17. The method of fabricating a semiconductor device according to claim 16 , wherein said ashing the photoresist comprises applying a gas that comprises oxygen during the dry etching.
18. A method of fabricating a semiconductor device, said method comprising:
forming a first metal film on a substrate;
forming a photoresist film on the first metal film;
forming a pattern in the photoresist film;
processing the first metal film by dry etching with the pattern as a mask;
ashing the photoresist without a bias at a predetermined temperature on the first metal film processed during the dry etching;
forming a dielectric film on the first metal film subjected to ashing of the photoresist; and
forming a second metal film on the dielectric film to form a metal-insulator-metal (MIM) capacitor,
wherein a thermal process is carried out at least between one of the ashing and said forming the dielectric film, and said forming the first metal film and said forming the photoresist film.
19. The method of fabricating a semiconductor device according to claim 18 , wherein a percentage of oxygen gas for the ashing is not more than a percentage of oxygen where an oxidation amount of the first metal layer is independent of a duration of said ashing.
20. The method of fabricating a semiconductor device according to claim 19 , wherein said ashing the photoresist comprises applying a gas that comprises oxygen during the dry etching.