3d integrated circuit layer interconnect

A method for manufacturing a device, the method comprising:

• forming a three-dimensional structure including a plurality of levels, including levels 0 to N, where N is at least two,
• in which level (i), for (i) equal to 1 through N, overlies level (i−1), and
• in which level (i), for (i) equal to 0 through N−1, includes a landing area (i) having a length in a longitudinal direction and a width in a transverse direction;
• forming a first mask having an opening overlying the landing areas on the plurality of levels, the opening in the first mask having a length in the longitudinal direction at least as large as a sum of the lengths of the landing areas (i) for (i) equal to 0 through N−1, and the opening in the first mask having a width overlying landing area (i) on level (i) for (i) equal to 0 through N−1 at least as large as the width of the landing area (i) on level (i);
• forming a second mask over the opening in the first mask, the second mask having a length in the longitudinal direction less than the length of the opening in the first mask, and having a width in the transverse direction at least as large as the width of the opening in the first mask;
• and
• iterating, over (j) from 0 through N−1, the steps of:
• etching using the first and second masks as etch masks, thereby forming an opening overlying the landing area (j) on level (j);
• and
• reducing the length of the second mask within the opening in the first mask by the length of the landing area (j+1) on level (j+1);
• incrementing j, and repeating said etching and said reducing for j less than or equal to N−1;
• forming insulating fill material within the openings in levels 1 to N;
• and
• forming conductors extending through the insulating fill in the openings to contact the landing areas on levels 0 to N−1.

A method for manufacturing a device, the method comprising:

• forming a plurality of levels having respective landing areas, the landing areas having respective lengths in a longitudinal direction and respective widths in a transverse direction, wherein forming the plurality of levels comprises forming a first level, forming a second level overlying the first level, and forming a third level overlying the second level;
• forming a first mask overlying the plurality of levels, the first mask having an opening with a length in the longitudinal direction and a width in the transverse direction, the length of the opening in the first mask at least as large as a sum of the lengths of the landing areas on the first, second and third levels, and the width of the opening in the first mask overlying the landing area on a given level in the plurality of levels at least as large as the width of the landing area on said given level;
• forming a second mask over the opening in the first mask, the second mask having a length in the longitudinal direction less than the length of the opening in the first mask, and having a width in the transverse direction at least as large as the width of the opening in the first mask;
• etching the third level using the first and second masks as etch masks, thereby forming a first opening in the third level overlying the landing area on the first level, the first opening having a width at least as large as the width of the landing area on the first level, and having a length at least as large the length of the landing area on the first level;
• reducing the length of the second mask within the opening in the first mask, thereby forming a third mask;
• etching the second and third levels using the first and third masks as etch masks, thereby extending the first opening through the second level, and forming a second opening in the third level adjacent the first opening, the second opening overlying the landing area on the second level, the second opening having a width at least as large as the width of the landing area on the second level, and having a length at least as large as the length of the landing area on the second level;
• and
• forming conductors extending through the first and second openings to contact the landing areas on the first and second levels.