Ultra-thin resist and SiON/oxide hard mask for metal etch

A method of forming a metal line, comprising:

• providing a semiconductor substrate comprising a metal layer, an oxide layer over the metal layer, and a silicon oxynitride layer over the oxide layer;
• depositing an ultra-thin photoresist over the silicon oxynitride layer, the ultra-thin photoresist having a thickness less than about 2,000 Å;
• irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 250 nm or less;
• developing the ultra-thin photoresist exposing a portion of the silicon oxynitride layer;
• etching the exposed portion of the silicon oxynitride layer exposing a portion of the oxide layer;
• etching the exposed portion of the oxide layer exposing a portion of the metal layer;
• and
• etching the exposed portion of the metal layer thereby forming the metal line,
• wherein the silicon oxynitride layer comprises a silicon oxime.

A method of etching metal to form metal lines, comprising, in relative order, the steps of:

• providing a semiconductor substrate comprising a metal layer, an oxide layer over the metal layer, and a silicon oxynitride layer over the oxide layer;
• depositing an ultra-thin photoresist over the silicon oxynitride layer, the ultra-thin photoresist having a thickness from about 500 Å to about 2,000 Å;
• irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 200 nm or less;
• developing the ultra-thin photoresist exposing a portion of the silicon oxynitride layer, wherein the exposed portion of the silicon oxynitride layer has a width of about 0.1 μm or less;
• etching the exposed portion of the silicon oxynitride layer exposing a portion of the oxide layer;
• etching the exposed portion of the oxide layer exposing a portion of the metal layer;
• and
• etching the exposed portion of the metal layer thereby forming metal lines.

A method of processing a semiconductor substrate, comprising, in relative order, the steps of:

• providing a semiconductor substrate comprising a metal layer, an oxide layer over the metal layer, and a silicon oxynitride layer over the oxide layer, wherein the metal layer comprises aluminum;
• depositing an ultra-thin photoresist over the silicon oxynitride layer, the ultra-thin photoresist having a thickness from about 500 Å to about 2,000 Å;
• irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 25 nm or less;
• developing the ultra-thin photoresist exposing a portion of the silicon oxynitride layer;
• etching the exposed portion of the silicon oxynitride layer exposing a portion of the oxide layer;
• etching the exposed portion of the oxide layer exposing a portion of the metal layer;
• and
• etching the exposed portion of the metal layer thereby forming a metal line having a width of about 0.1 μm or less.