Methods of forming alignment marks during patterning of semiconductor material

A patterning method, comprising:

• providing a mass of semiconductor material;
• a memory array region being defined to encompass a first region of the mass, and a reference mark region being defined to encompass a second region of the mass;
• forming a first pattern set to extend across the first region, and simultaneously forming a third pattern set to extend across the second region;
• the first pattern set comprising first lines and first trenches between the first lines;
• the third pattern set comprising alignment marks;
• extending the first trenches into the mass to form rails from the semiconductor material of the mass within the first region;
• the rails being on a first pitch;
• the alignment marks being parallel to the rails, and being on a third pitch;
• forming a second pattern set to extend across the first region, and simultaneously forming a fourth pattern set to extend across the second region;
• said second pattern set comprising first openings;
• the first openings being on a second pitch;
• the fourth pattern set comprising second openings which are on a fourth pitch;
• extending the first openings into the semiconductor material to subdivide the rails into active-region-pillars;
• and
• extending the second openings through the alignment marks to transform the alignment marks into an overlay pattern.

A patterning method, comprising:

• providing a mass of semiconductor material;
• a memory array region being defined to encompass a first region of the mass, and an alignment mark region being defined to encompass a second region of the mass;
• forming a first pattern set to extend across the first region, the first pattern set comprises first patterning lines spaced from one another by first trenches;
• forming a third pattern set to extend across the second region;
• the third pattern set comprising first reference lines which are parallel with the first patterning lines;
• extending the first trenches into the semiconductor material to form rails extending across the first region;
• forming a second pattern set to extend across the first region;
• the second pattern set comprising second patterning lines spaced from one another by second trenches;
• extending the second trenches into the semiconductor material to subdivide the rails into active-region-pillars;
• forming a fourth pattern set to extend across the second region;
• the fourth pattern set comprising second reference lines which are parallel with the second patterning lines;
• and
• wherein:
• the first patterning lines extend along a first direction, and the second patterning lines extend along a second direction which crosses the first direction;
• an angle between the first and second directions is less than 90°;
• and
• the first and second reference lines form an overlay pattern within the second region.