Method of forming and repairing a mask for photolithography

A method of forming a mask for photolithography, comprising the steps of:

• forming a transparent film having an electrical conductivity on a mask substrate which is transparent to light;
• forming an opaque conductive film on the transparent film;
• immersing in an electrolytic solution an electrode having a sharp front end and the mask substrate having thereon the transparent film and the opaque conductive film;
• positioning the sharp front end of the electrode and the opaque conductive film close to one another;
• controlling a distance between the sharp front end of the electrode and a desired portion of the opaque conductive film by detecting a tunneling current flowing therebetween;
• scanning the mask substrate and the electrode relative to each other in two dimensions;
• and
• forming a transparent pattern in the opaque conductive film by electrochemically etching the opaque conductive film.

A method of repairing a mask for photolithography, comprising the steps of:

• providing an electrode having a sharp front end;
• immersing the electrode and a mask substrate having an opaque conductive pattern thereon in an electrolytic solution;
• positioning the sharp front end of the electrode in close proximity to a portion of the opaque conductive pattern which neighbors on a portion of the opaque conductive pattern which is to be repaired;
• controlling a distance between the sharp front end of the electrode and the portion of the opaque conductive pattern neighboring on the portion thereof to be repaired by detecting a tunneling current flowing therebetween;
• and
• applying a voltage between the electrode and the opaque conductive pattern for depositing an opaque material onto the portion of the opaque conductive pattern to be repaired.

A method of repairing a mask for photolithography, comprising the steps of:

• immersing a mask substrate having an opaque conductive pattern thereon and an electrode having a sharp front end in an electrolytic solution;
• positioning the sharp front end of the electrode and a portion of the opaque conductive pattern to be repaired in close proximity to one another;
• controlling a distance between the sharp front end of the electrode and the portion of the opaque conductive pattern to be repaired by detecting a tunneling current flowing therebetween;
• and
• applying a voltage between the electrode and the opaque conductive pattern to electrochemically dissolve an opaque material from the portion of the opaque conductive pattern to be repaired into the electrolytic solution.

A method of forming a mask for photolithography, comprising the steps of:

• forming a transparent conductive film on a glass substrate;
• forming an opaque conductive film on the transparent conductive film;
• providing an electrode having a sharp front end;
• immersing in an electrolytic solution the electrode and the glass substrate having thereon the transparent conductive film and the opaque conductive film;
• positioning the sharp front end of the electrode and the opaque conductive film in close proximity to one another;
• controlling a distance between the sharp front end of the electrode and the opaque conductive film;
• scanning the glass substrate and the sharp front end of the electrode relative to each other while maintaining the distance between the sharp front end of the electrode and the opaque conductive film constant;
• and
• forming a transparent pattern in the opaque conductive film by electrochemically etching the opaque conductive film while applying a voltage between the opaque conductive film and the electrode.