Plasma processing method and manufacturing method of semiconductor device
A plasma processing method in which performing a plasma etching on metal layers formed on a substrate is conducted to form a pattern having the metal layers in a stacked structure, and then a deposit containing a metal that forms the metal layers and being deposited on a sidewall portion of the pattern is removed, the method includes: forming a protective layer by forming an oxide or chloride of the metal on sidewall portions of the metal layers; removing the deposit by applying a plasma of a gas containing fluorine atoms; and reducing the oxide or chloride of the metal by applying a plasma containing hydrogen after forming the protective layer and removing the deposit.
1. A plasma processing method of removing a deposit on a sidewall portion of a pattern of having metal layers in a stacked structure on a substrate, the method comprising:
preparing the substrate with the pattern having metal layers in a stacked structure formed by dry processing, the stacked structure having a sidewall on a sidewall portion of which a deposit is deposited, the deposit containing at least one of metals of the metal layers;
subjecting the stacked structure having said deposit to a protective layer forming step in which an oxide or chloride of the at least one of the metals is formed on the sidewall of the stacked structure having said deposit;
applying a plasma of a gas containing fluorine atoms to remove the deposit; and
applying a plasma containing hydrogen after forming the protective layer and removing the deposit, so as to reduce the oxide or chloride of the at least one of the metals.
2. The plasma processing method according to claim 1 ,
wherein the forming an oxide or chloride of the one of the metals comprises applying a plasma of an oxygen gas to form the oxide of the one of the metals or applying a chlorine plasma to form the chloride of the one of the metals,
the forming an oxide or chloride of the one of the metals on the sidewall of the stacked structure having said deposit and applying a plasma of a gas containing fluorine atoms are alternately repeated to be performed a plurality of times, and
the applying a plasma containing hydrogen to reduce the oxide or chloride of the one of the metals is performed thereafter.
3. The plasma processing method according to claim 1 ,
wherein a plasma of an oxygen gas is applied to form the oxide of the metal or a plasma of a chlorine gas is applied to form the chloride of the metal in forming the protective layer,
forming the protective layer and removing the deposit are simultaneously conducted, and
a ratio of a flow rate of the oxygen gas or the chlorine gas to a flow rate of the gas containing fluorine atoms (flow rate of oxygen gas or chlorine gas/flow rate of gas containing fluorine atoms) is set to greater than 25.
4. The plasma processing method according to claim 1 ,
wherein the substrate is heated in an oxygen gas atmosphere to form the oxide of forming the metal layer, and forming the protective layer is performed only once before the removing deposit.
5. The plasma processing method according to claim 1 ,
wherein the gas containing fluorine atoms is at least any one of NF 3 , CHF 3 and CH 2 F 2 .
6. The plasma processing method according to claim 1 ,
wherein the metal layers contain tungsten.
7. The plasma processing method according to claim 1 ,
wherein the metal layers contain titanium.
8. A manufacturing method of a semiconductor device, comprising:
forming metal layers on a substrate;
performing a plasma etching on the metal layers to form a pattern having the metal layers in a stacked structure formed by dry processing on the substrate, the stacked structure having a sidewall on a sidewall portion of which a deposit is deposited, the deposit containing at least one of metals of the metal layers;
subjecting the stacked structure having said deposit to a protective layer forming step in which an oxide or chloride of the at least one of the metals is formed on the sidewall of the stacked structure having said deposit;
applying a plasma of a gas containing fluorine atoms to remove the deposit; and
applying a plasma containing hydrogen, after forming the protective layer and removing the deposit, so as to reduce the oxide or chloride of the metal.