Lithographic method using double exposure techniques, mask position shifting and light phase shifting

A method for forming masking features upon a substrate wherein the substrate has a top surface made of a masking layer, the method comprising the steps of:

• positioning a phase shifting mask in a first position in close proximity to the substrate, the first position exposing a first surface area of the masking layer;
• exposing the masking layer to first radiation wherein the first radiation is passed through the phase shifting mask to form a first plurality of exposed areas of the masking layer;
• positioning the phase shifting mask in a second position in close proximity to the substrate, the second position exposing a second surface area of the masking layer wherein the second surface area and the first surface area at least partially coincide;
• and
• exposing the masking layer to second radiation wherein the second radiation is passed through the phase shifting mask to form a second plurality of exposed areas of the masking layer, the first plurality of exposed areas partially overlapping the second plurality of exposed areas.

A method for forming masking features upon a semiconductor wafer wherein the semiconductor wafer has a top surface made of a masking layer, the method comprising the steps of:

• positioning a phase shifting mask in a first position adjacent the semiconductor wafer, the first position being adjacent a first surface area of the masking layer;
• exposing the masking layer to light wherein the light is passed through the phase shifting mask, the light forming an exposed region of the masking layer, the exposed region having an exposed surface area;
• positioning the phase shifting mask in a second position adjacent the semiconductor wafer wherein the second position is different from the first position, the second position being adjacent a second surface area of the masking layer wherein the first and second surface areas partially overlap;
• and
• exposing the masking layer to light wherein the light is passed through the phase shifting mask, the light enlarging the exposed surface area of the exposed region of the masking layer within the first surface area.

A method for forming masking features upon a silicon semiconductor wafer wherein the silicon semiconductor wafer has a top surface made of a photo-sensitive layer, the method comprising the steps of:

• positioning a phase shifting mask in a first position in close proximity to the semiconductor wafer, the first position masking a first surface area of the photo-sensitive layer;
• exposing the photo-sensitive layer to light wherein the light is passed through the phase shifting mask to form both first exposed regions of the photo-sensitive layer and first unexposed regions of the photo-sensitive layer, the first unexposed regions having a first unexposed total surface area;
• positioning the phase shifting mask in a second position in close proximity to the semiconductor wafer wherein the second position is different from the first position, the second position masking a second surface area of the photo-sensitive layer wherein the second surface area partially coincides with the first surface area;
• exposing the photo-sensitive layer to light wherein the light is passed through the phase shifting mask to form second exposed regions of the photo-sensitive layer and second unexposed regions of the photo-sensitive layer, the second unexposed regions having a second unexposed total surface area wherein the second unexposed total surface area is less than the first unexposed total surface area and;
• selectively removing portions of one of either the first and second exposed regions or the first and second unexposed regions to form said masking features.

A method for forming masking features upon a silicon semiconductor wafer wherein the silicon semiconductor wafer has a top surface made of a photoresist layer, the method comprising the steps of:

• positioning a phase shifting mask in a first position adjacent the semiconductor wafer, the first position exposing a first surface area of the photoresist layer, the phase shifting mask having at least one transparent region wherein the at least one transparent region passes light with a pre-defined 0.degree. phase shift, and having at least one phase shifting region wherein the at least one phase shifting region passes light, the light being phase shifted in comparison to the light passed by the at least one transparent region;
• exposing the photoresist layer to light wherein the light is passed through the phase shifting mask, a first region of light being transmitted through the at least one transparent region and a second region of light is transmitted through the at least one phase shifting region, wherein the first region of light is defined as having a 0.degree. phase shift and the second region of light is substantially phase shifted in comparison to the first region of light to form both exposed regions and unexposed destructive interference regions of the photoresist layer;
• positioning the phase shifting mask in a second position adjacent the semiconductor wafer wherein the second position is different from the first position, the second position exposing a portion of the first surface area of the photoresist layer;
• exposing the photoresist layer to light wherein the light is passed through the phase shifting mask to reduce the surface area of the unexposed destructive interference regions of the masking layer to form said masking features from said photoresist layer and;
• selectively removing portions of the photoresist layer to form said masking features.

A method for forming masking features upon a semiconductor wafer wherein the semiconductor wafer has a top surface made of a masking layer, the method comprising the steps of:

• positioning a phase shifting mask in a first position in close proximity to the semiconductor wafer, the first position being aligned adjacent a first surface area of the masking layer;
• forming a first plurality of unexposed regions from the masking layer through selective energy exposure through the phase shifting mask;
• positioning the phase shifting mask in a second position in close proximity to the semiconductor wafer wherein the second position is different from the first position, the second position being aligned adjacent a portion of the first surface area of the masking layer wherein the first surface area is partially exposed by the phase shifting mask while the phase shifting mask is in the second position;
• and
• forming a second plurality of unexposed regions from the masking layer through the selective energy exposure through the phase shifting mask, the second plurality of unexposed regions being positioned differently from the first plurality of unexposed regions, the combination of the first and second pluralities of unexposed regions being used to form said masking features from the masking layer.