Substrate processing method and substrate processing apparatus
A technique improves selectivity in etching of a silicon-containing film over etching of a mask in plasma etching. A substrate processing method includes placing a substrate in a chamber in a plasma processing apparatus. The substrate includes a silicon-containing film and a mask on the silicon-containing film. The substrate processing method further includes generating plasma from a first process gas containing a hydrogen fluoride gas in the chamber. The generating plasma includes etching the silicon-containing film with a chemical species contained in the plasma. A flow rate of the hydrogen fluoride gas is at least 80 vol % of a total flow rate of now-inert components of the first process gas.
1 . A substrate processing apparatus, comprising:
a first gas container for containing a hydrogen fluoride gas;
a second gas container for containing a carbon-containing gas;
a first valve connected to the first gas container;
a second valve connected to the second gas container;
a flow controller connected to the first and second gas containers, the flow controller being configured to control a flow rate of each of the first and second gas containers with the first valve and the second valve;
a chamber having a gas inlet, the first and second valves being located between the flow controller and the gas inlet of the chamber;
a plasma generator;
a controller configured to
control a placement of a substrate in the chamber, the substrate including a silicon-containing film and a mask on the silicon-containing film,
control the flow controller and the first and second valves to controllably input to the chamber a first process gas containing the hydrogen fluoride gas and the carbon-containing gas, and
control the plasma generator to generate plasma from the first process gas containing the hydrogen fluoride gas and the carbon-containing gas and etch the silicon-containing film; and
a direct current (DC) power supply configured to supply, to a substrate support that supports the substrate, a negative direct current (DC) voltage in pulses, wherein
the controller is configured to control the flow controller and the first and second valves such that a flow rate of the hydrogen fluoride gas is at least 80 vol % of a total flow rate of the first process gas excluding an inert gas being a noble gas or a nitrogen-containing gas, and
the controller is configured to control the substrate processing apparatus to perform an etching of the silicon-containing film in multiple stages, a ratio of the flow rate of the hydrogen fluoride gas relative to the total flow rate of the first process gas excluding the inert gas in a final stage of the multiple stages of the etching being lower than the ratio in an initial stage of the multiple stages of the etching.
2 . The substrate processing apparatus according to claim 1 , wherein
the carbon-containing gas contains at least one selected from the group consisting of a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas.
3 . The substrate processing apparatus according to claim 1 , wherein
the silicon-containing film includes at least one selected from the group consisting of a film stack including a silicon oxide film and a silicon nitride film, a polysilicon film, and a film stack including a silicon oxide film and a polysilicon film.
4 . The substrate processing apparatus according to claim 1 , wherein
the mask includes a carbon-containing mask or a metal-containing mask.
5 . The substrate processing apparatus according to claim 4 , wherein
the mask includes the carbon-containing mask, and
the carbon-containing mask comprises at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.
6 . The substrate processing apparatus according to claim 1 , wherein the controller is further configured to:
control supplying of a second process gas into the chamber; and
control the plasma generator to generate plasma from the second process gas in the chamber to clean an inside of the chamber.
7 . The substrate processing apparatus according to claim 6 , wherein
the second process gas contains at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas.
8 . The substrate processing apparatus according to claim 1 , wherein the controller is further configured to:
control supplying of a third process gas into the chamber; and
control the plasma generator to generate plasma from the third process gas in the chamber and deposit a precoat film on an inner wall of the chamber before the substrate is placed in the chamber.
9 . The substrate processing apparatus according to claim 8 , wherein the third process gas contains a silicon-containing gas and an oxygen-containing gas.
10 . The substrate processing apparatus according to claim 1 , wherein the first process gas further comprises WF 6 gas.
11 . The substrate processing apparatus according to claim 1 , wherein the first process gas further comprises at least one selected from the group consisting of PBr 3 gas, PBr 5 gas and PI 3 gas.
12 . The substrate processing apparatus according to claim 1 , wherein the first process gas further comprises at least one selected from the group consisting of PF 3 gas, PF 5 gas, PCl 3 gas and PCl 5 gas.
13 . The substrate processing apparatus according to claim 1 , wherein the carbon-containing gas contains at least one selected from the group consisting of CF 4 , C 2 F 2 , C 2 F 4 , C 3 F 8 , C 4 F 6 , C 4 F 8 , and C 5 F 8 .
14 . The substrate processing apparatus according to claim 1 , wherein the carbon-containing gas contains at least one selected from the group consisting of CHF 3 , CH 2 F 2 , CH 3 F, C 2 HF 5 , C 2 H 2 F 4 , C 2 H 3 F 3 , C 2 H 4 F 2 , C 3 HF 7 , C 3 H 2 F 6 , C 3 H 2 F 4 , C 3 H 3 F 5 , C 4 H 5 F 5 , C 5 H 2 F 10 , c-C 5 H 3 F 7 , and C 3 H 2 F 4 .
15 . The substrate processing apparatus according to claim 1 , wherein the carbon-containing gas contains at least one selected from the group consisting of CH 4 , C 2 H 6 , C 3 H 6 , C 3 H 8 , and C 4 H 10 .
16 . The substrate processing apparatus according to claim 1 ,
wherein the controller is configured to control a flow of a heat exchange medium through an electrostatic chuck on which the substrate is placed so as to adjust a temperature of the electrostatic chuck to 0° C. or lower before the plasma generator generates the plasma that etches the silicon-containing film.
17 . The substrate processing apparatus according to claim 1 , wherein
the controller is configured to control the flow controller and the first and second valves such that a flow rate of the hydrogen fluoride gas is above 90 vol % of the total flow rate of the first process gas excluding the inert gas.
18 . The substrate processing apparatus according to claim 1 , wherein
the controller is configured to control the flow controller and the first and second valves such that a flow rate of the hydrogen fluoride gas is above 95 vol % of the total flow rate of the first process gas excluding the inert gas.
19 . The substrate processing apparatus according to claim 1 , wherein
the first process gas further contains a phosphorus-containing gas, the phosphorus-containing gas protecting a sidewall of a feature being formed in the silicon-containing film while the silicon-containing film is etched with the hydrogen fluoride gas.
20 . The substrate processing apparatus according to claim 19 , wherein
the controller is configured to control performing an etching of the silicon-containing film while adjusting a composition of the first process gas based on an aspect ratio of an area of the silicon-containing film being etched, such that a flow rate ratio of the phosphorus-containing gas is increased when etching an area with a lower aspect ratio compared to when etching an area with a higher aspect ratio.