Alternating phase shifting mask

An alternating phase shifting mask (Alt-PSM) comprising:

• a quartz substrate;
• a dense line pattern formed on the substrate;
• at least one semi-dense line pattern formed on the substrate along an edge of the dense line pattern;
• a first phase shifting area having a first selected width positioned contiguous with the dense line pattern between the dense line pattern and the semi-dense line pattern;
• a second phase shifting area having a second selected width positioned contiguous with the semi-dense line pattern between the dense line pattern and the semi-dense line pattern, the second phase shifting area being disconnected from the first phase shifting area;
• and
• a third phase shifting area positioned contiguous with the semi-dense line pattern opposite to the second phase shifting area, the third phase shifting area having a width substantially equal to the width of the second phase shifting area;
• wherein a phase difference between the first phase shifting area and the second phase shifting area is approximately 0 degrees, while the phase difference between the second phase shifting area and the third phase shifting area is approximately 180 degrees.