Etching gas, etching method, and method for producing semiconductor device
An etching gas and an etching method capable of selectively etching an etching object containing silicon as compared with a non-etching object. The etching gas contains fluorobutene represented by a general formula C 4 H x F y , in which x is 1 or more and 7 or less, y is 1 or more and 7 or less, and x+y is 8. The etching gas contains or does not contain at least one of alkali metals and alkaline earth metals as metal impurities, and the sum of the concentrations of alkali metals and alkaline earth metals when contained is 5000 ppb by mass or less. The etching method includes an etching step of bringing the etching gas into contact with a member to be etched ( 12 ) having an etching object and a non-etching object, and selectively etching the etching object as compared with the non-etching object. The etching object contains silicon.
1 . An etching gas comprising:
fluorobutene represented by a general formula C 4 H x F y , in which x is 1 or more and 7 or less, y is 1 or more and 7 or less, and x+y is 8, wherein
the etching gas contains at least one of alkali metals and alkaline earth metals as metal impurities, and a sum of concentrations of alkali metals and alkaline earth metals is 5000 ppb by mass or less.
2 . The etching gas according to claim 1 , wherein
the etching gas further contains or at least one of copper, zinc, manganese, cobalt, and silicon as the metal impurities, and
a total sum of concentrations of alkali metals and alkaline earth metals, and copper, zinc, manganese, cobalt, and silicon when contained is 10000 ppb by mass or less.
3 . The etching gas according to claim 2 , wherein the alkali metal is at least one of lithium, sodium, and potassium, and the alkaline earth metal is at least one of magnesium and calcium.
4 . The etching gas according to claim 2 , wherein the fluorobutene is at least one selected from 1,1,1,4,4,4-hexafluoro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene, 3,3,4,4,4-pentafluoro-1-butene, and 2,3,3,4,4,4-hexafluoro-1-butene.
5 . The etching gas according to claim 1 , wherein the alkali metal is at least one of lithium, sodium, and potassium, and the alkaline earth metal is at least one of magnesium and calcium.
6 . The etching gas according to claim 5 , wherein the fluorobutene is at least one selected from 1,1,1,4,4,4-hexafluoro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene, 3,3,4,4,4-pentafluoro-1-butene, and 2,3,3,4,4,4-hexafluoro-1-butene.
7 . The etching gas according to claim 1 , wherein the fluorobutene is at least one selected from 1,1,1,4,4,4-hexafluoro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene, 3,3,4,4,4-pentafluoro-1-butene, and 2,3,3,4,4,4-hexafluoro-1-butene.
8 . An etching method comprising:
an etching step of bringing the etching gas according to claim 1 into contact with a member to be etched having an etching object which is an object to be etched by the etching gas and a non-etching object which is not an object to be etched by the etching gas, and selectively etching the etching object as compared with the non-etching object, wherein
the etching object contains silicon.
9 . The etching method according to claim 8 , comprising:
before the etching step, a metal impurity removing step of setting the sum of the concentrations of alkali metals and alkaline earth metals contained in the etching gas to 5000 ppb by mass or less.
10 . The etching method according to claim 9 , wherein the etching gas is a gas containing only the fluorobutene or a mixed gas containing the fluorobutene and a dilution gas.
11 . The etching method according to claim 8 , wherein the etching gas is a gas containing only the fluorobutene or a mixed gas containing the fluorobutene and a dilution gas.
12 . The etching method according to claim 11 , wherein the dilution gas is at least one selected from a nitrogen gas, helium, argon, neon, krypton, and xenon.
13 . A method for producing a semiconductor device using the etching method according to claim 8 ,
the member to be etched being a semiconductor substrate having the etching object and the non-etching object, and the method comprising:
a treatment step of removing at least a part of the etching object from the semiconductor substrate by the etching.
14 . An etching method comprising:
an etching step of bringing the etching gas according to claim 2 into contact with a member to be etched having an etching object which is an object to be etched by the etching gas and a non-etching object which is not an object to be etched by the etching gas, and selectively etching the etching object as compared with the non-etching object, wherein
the etching object contains silicon.
15 . An etching method comprising:
an etching step of bringing the etching gas according to claim 5 into contact with a member to be etched having an etching object which is an object to be etched by the etching gas and a non-etching object which is not an object to be etched by the etching gas, and selectively etching the etching object as compared with the non-etching object, wherein
the etching object contains silicon.
16 . An etching method comprising:
an etching step of bringing the etching gas according to claim 7 into contact with a member to be etched having an etching object which is an object to be etched by the etching gas and a non-etching object which is not an object to be etched by the etching gas, and selectively etching the etching object as compared with the non-etching object, wherein
the etching object contains silicon.
17 . A method for producing a semiconductor device using the etching method according to claim 9 ,
the member to be etched being a semiconductor substrate having the etching object and the non-etching object, and the method comprising:
a treatment step of removing at least a part of the etching object from the semiconductor substrate by the etching.
18 . A method for producing a semiconductor device using the etching method according to claim 11 ,
the member to be etched being a semiconductor substrate having the etching object and the non-etching object, and the method comprising:
a treatment step of removing at least a part of the etching object from the semiconductor substrate by the etching.
19 . A method for producing a semiconductor device using the etching method according to claim 12 ,
the member to be etched being a semiconductor substrate having the etching object and the non-etching object, and the method comprising:
a treatment step of removing at least a part of the etching object from the semiconductor substrate by the etching.