Plasma processing method
A plasma processing method of forming a protective film for suppressing etching only a desired material in a pattern to etch a pattern is provided. A plasma processing method for plasma etching a film to be etched formed on a sample includes a cleaning step of cleaning a surface of the sample, a protective film forming step of selectively forming a protective film on a desired material in a pattern formed on the film to be etched, an oxidation step of oxidizing the protective film after the protective film forming step, and an etching step of plasma-etching the film to be etched.
1 . A plasma processing method for plasma etching a film to be etched formed on a sample, comprising:
a cleaning step of cleaning a surface of the sample;
a protective film forming step of selectively forming a protective film on a desired material in a pattern formed on the film to be etched;
an oxidation step of oxidizing the protective film after the protective film forming step; and
an etching step of plasma etching the film to be etched,
wherein the protective film forming step further comprises supplying a SiCl 4 gas and a CL gas to the pattern at a SiCl 4 /Cl 2 flow rate ratio of less than 1 while forming a plasma using radio frequency power to cause the protective film to be formed only on the desired material in the pattern and not on the film to be etched.
2 . The plasma processing method according to claim 1 ,
wherein a composition ratio of oxygen elements in the oxidized protective film is such that an etching rate of the oxidized protective film is lower than an etching rate of the film to be etched.
3 . The plasma processing method according to claim 2 ,
wherein the protective film contains silicon elements, and
a composition ratio of the oxygen elements to the silicon elements in the protective film is a value within a range of 0.4 to 0.6.
4 . The plasma processing method according to claim 3 ,
wherein energy of ions irradiated to the sample in the etching step is energy that does not pass through the protective film.
5 . The plasma processing method according to claim 2 , further comprising:
a determination step of monitoring a spectrum of interference light reflected from the sample, and
determining whether the composition ratio of the oxygen elements is within a desired composition ratio range based on a result of comparison between the spectrum of the interference light and the monitored spectrum of the interference light when the composition ratio of the oxygen elements is a desired composition ratio.
6 . The plasma processing method according to claim 2 ,
wherein after the etching step, the protective film forming step is performed if a depth of the film to be etched has not reached a predetermined depth.
7 . The plasma processing method according to claim 2 ,
wherein the protective film forming step uses a mixed gas of the SiCl 4 gas, H 2 gas, and the Cl 2 gas.
8 . The plasma processing method according to claim 1 ,
wherein after the etching step, the protective film forming step is performed if a depth of the film to be etched has not reached a predetermined depth.
9 . The plasma processing method according to claim 8 ,
wherein the protective film forming step uses a mixed gas of the SiCl 4 gas, H 2 gas, and the Cl 2 gas.
10 . The plasma processing method according to claim 1 ,
wherein the protective film forming step uses a mixed gas of the SiCl 4 gas, H 2 gas, and the Cl 2 gas.