Methods and apparatus for ruthenium oxide reduction on extreme ultraviolet photomasks

A method for reducing ruthenium oxides on an extreme ultraviolet (EUV) photomask, comprising:

• flowing a reducing agent gas and a carrier gas into a remote plasma generator;
• heating the EUV photomask to a temperature of approximately 100 degrees Celsius to approximately a thermal budget of the EUV photomask;
• generating a plasma in the remote plasma generator using an RF power source;
• and
• flowing gases from the remote plasma generator into an EUV photomask processing chamber, wherein a remote plasma is formed above the EUV photomask to generate a self-bias on the EUV photomask and wherein the gases in the EUV photomask processing chamber react with a ruthenium (Ru) oxide layer on a Ru capping layer to reduce the Ru oxide layer to Ru metal.

A method for reducing ruthenium oxides on an extreme ultraviolet (EUV) photomask, comprising:

• flowing a reducing agent gas and a carrier gas into an atmospheric-pressure (AP) plasma generator in an EUV photomask processing chamber;
• heating the EUV photomask to a temperature of approximately 100 degrees Celsius to approximately a thermal budget of the EUV photomask;
• generating a plasma above the EUV photomask with the AP plasma generator using an RF power source;
• and
• flowing the reducing agent gas and the carrier gas into the plasma and onto a top surface of the EUV photomask, wherein the reducing agent gas reacts with a ruthenium (Ru) oxide layer on a Ru capping layer to reduce the Ru oxide layer to Ru metal.

An apparatus for reducing ruthenium (RU Ru) oxides on an extreme ultraviolet (EUV) photomask, comprising:

• an EUV photomask processing chamber with a photomask support body attached to a photomask support, the photomask support body supporting an EUV photomask when present;
• a reducing agent gas supply fluidly connected to the EUV photomask processing chamber;
• a heater electrode in the photomask support body that is configured to heat the EUV photomask when present to a range of approximately 100 degrees to approximately 150 degrees;
• a first valve that controls a reducing agent gas that enters into the EUV photomask processing chamber;
• a second valve that controls effluent gases that exit the EUV photomask processing chamber;
• and
• a controller that regulates the first valve and the second valve to adjust a pressure inside of the EUV photomask processing chamber, wherein the pressure is adjustable from zero psi to 2500 psi and is adjusted, by the controller, to control a reduction rate to reduce Ru oxides on a Ru capping layer on the EUV photomask.

An apparatus for reducing ruthenium (Ru) oxides on an extreme ultraviolet (EUV) photomask, comprising:

• an EUV photomask processing chamber with a photomask support body attached to a photomask support, the photomask support body supporting an EUV photomask when present;
• a heater electrode in the photomask support body that is configured to heat the EUV photomask when present to a range of approximately 100 degrees to approximately 150 degrees to enhance a reduction rate of Ru oxides;
• a reducing agent gas supply fluidly connected to the EUV photomask processing chamber;
• a carrier gas supply fluidly connected to the EUV photomask processing chamber;
• and
• a remote plasma generator fluidly connected to the EUV photomask processing chamber, wherein the remote plasma generator is configured to form a remote plasma above the EUV photomask to generate a self-bias on the EUV photomask and is configured to allow a reducing agent gas from the reducing agent gas supply and a carrier gas from the carrier gas supply flow through the remote plasma generator when plasma is generated in the remote plasma generator and subsequently allow the reducing agent gas, the carrier gas, and the plasma to flow into the EUV photomask processing chamber to interact with the EUV photomask when present to reduce Ru oxides on a Ru capping layer on the EUV photomask.

An apparatus for reducing ruthenium (Ru) oxides on an extreme ultraviolet (EUV) photomask, comprising:

• an EUV photomask processing chamber with a photomask support body attached to a photomask support, the photomask support body supporting an EUV photomask when present;
• a heater electrode in the photomask support body that is configured to heat the EUV photomask when present to a range of approximately 100 degrees to approximately 150 degrees to enhance a reduction rate of Ru oxides;
• a reducing agent gas supply fluidly connected to the EUV photomask processing chamber;
• a carrier gas supply fluidly connected to the EUV photomask processing chamber;
• and
• an atmospheric-pressure (AP) plasma generator in the EUV photomask processing chamber, wherein the AP plasma generator is configured to allow a reducing agent gas from the reducing agent gas supply and a carrier gas from the carrier gas supply to flow through the AP plasma generator when dielectric barrier discharge plasma is generated by the AP plasma generator directly above the EUV photomask and subsequently allow the reducing agent gas and the carrier gas to flow onto a top surface of the EUV photomask to reduce Ru oxides on a Ru capping layer on the EUV photomask.