Etching method and plasma processing apparatus
A disclosed etching method includes (a) forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus. The etching method further includes (b) etching an etch film of a substrate with plasma generated from an etching gas that includes a hydrogen fluoride gas and a hydrofluorocarbon gas within the chamber. The substrate includes the etch film, which is a silicon-containing film, and a mask containing carbon and provided on the etch film.
1 . An etching method comprising:
forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus prior to placing a substrate within the chamber; and
placing the substrate within the chamber and etching an etch film of the substrate with plasma generated from an etching gas including a hydrogen fluoride gas and a hydrofluorocarbon gas within the chamber,
wherein the substrate includes:
the etch film, which is a silicon-containing film; and
a mask containing carbon provided on the etch film,
the protective film is formed using a film-forming gas, the protective film including:
a first film containing silicon; and
a second film containing carbon formed on the first film,
the method further comprises:
forming the first film by plasma-enhanced chemical vapor deposition (CVD) using a gas that includes:
SiCl 4 and H 2 ; and
forming the second film by plasma-enhanced CVD using CH 4 gas,
the plasma processing apparatus is a capacitively coupled plasma processing apparatus, and includes a substrate support provided within the chamber and an upper electrode provided above the substrate support, and
the method further comprises applying a negative direct-current voltage to the upper electrode in a state where plasma of an inert gas is being generated in the chamber, after forming the protective film and before placing the substrate within the chamber.
2 . The etching method according to claim 1 , wherein the protective film has a carbon content that increases according to a distance in a thickness direction thereof from the surface in the chamber.
3 . The etching method according to claim 2 ,
wherein in the forming of the protective film, a ratio of a flow rate of the CH 4 gas to a total flow rate of the film-forming gas is increased with time.
4 . The etching method according to claim 1 , wherein a surface of the upper electrode on a side of an internal space of the chamber is provided by a ceiling plate formed of silicon.
5 . The etching method according to claim 1 , further comprising:
modifying the surface in the chamber before forming the protective film.
6 . The etching method according to claim 5 , wherein the modifying the surface in the chamber is performed, after chamber cleaning, and by generating plasma from a noble gas within the chamber.
7 . The etching method according to claim 1 , further comprising:
performing roughening treatment of a surface of the protective film after forming the protective film and before placing the substrate within the chamber to enhance adhesion of reactive species generated in the etching of the etch film.
8 . The etching method according to claim 7 , wherein plasma is generated from a hydrogen gas within the chamber during performing the roughening treatment of the surface of the protective film.
9 . An etching method comprising:
forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus prior to placing a substrate within the chamber; and then
placing the substrate within the chamber and etching an etch film of the substrate with plasma generated from an etching gas containing a hydrogen fluoride gas and a hydrogen-containing gas within the chamber,
wherein the substrate includes the etch film, and a mask provided on the etch film,
the protective film is formed of a same type of material as a material of the mask,
the forming the protective film includes forming:
a first film containing silicon; and
a second film containing carbon formed on the first film,
the method further comprises:
forming the first film by plasma-enhanced chemical vapor deposition (CVD) using a gas that includes:
SiCl 4 and H 2 ; and
forming the second film by plasma-enhanced CVD using CH 4 gas, the second film being comprised of a material different from a material of the first film,
the plasma processing apparatus is a capacitively coupled plasma processing apparatus, and includes a substrate support provided within the chamber and an upper electrode provided above the substrate support, and
the method further comprises applying a negative direct-current voltage to the upper electrode in a state where plasma of an inert gas is being generated in the chamber, after forming the protective film and before placing the substrate within the chamber.
10 . The etching method according to claim 9 , wherein the hydrogen-containing gas includes at least one selected from a group consisting of H 2 , CH 4 , C 2 H 2 , C 4 H 2 F 6 , CH 2 F 2 , CH 3 F, CHF 3 , H 2 O, HCl, HBr, and HI.
11 . The etching method according to claim 9 , wherein
a surface of the upper electrode on a side of an internal space of the chamber is provided by a ceiling plate formed of silicon.
12 . The etching method according to claim 9 , further comprising:
modifying the surface in the chamber before forming the protective film.
13 . The etching method according to claim 9 , further comprising:
performing roughening treatment of a surface of the protective film after forming the protective film and before placing the substrate within the chamber to enhance adhesion of reactive species generated in the etching of the etch film.