Use of sub divided pattern for alignment mark recovery after inter-level dielectric planarization

A method of recovering alignment marks, comprising the sequential steps of:

• providing a substrate having an active region and a number of alignment regions wherein each said alignment region has alignment marks formed therein;
• forming a layer of first conductor material on said substrate covering said active region and said alignment regions;
• providing a first mask element;
• providing a second mask element;
• providing a first mask having a first device region, a first peripheral region adjacent to and external to said first device region, said first mask element formed in said first peripheral region, said second mask element formed in said first peripheral region, and a first device pattern formed in said first device region;
• providing a second mask having a second device region, a second peripheral region adjacent to and external to said second device region, said first mask element formed in said second peripheral region, and a second device pattern formed in said second device region;
• forming a first photoresist mask on said layer of first conductor material using photolithographic processing, said first mask, said first mask element, said second mask element, and said first device pattern wherein a part of said first photoresist mask forms an alignment mark protection pattern in each said of alignment regions of said substrate covering said alignment marks in that said alignment region;
• etching away that part of said layer of first conductor material not covered by said first photoresist mask;
• removing said first photoresist mask;
• forming a layer of inter-level dielectric on said substrate;
• planarizing said layer of inter-level dielectric;
• forming a second photoresist mask on said planarized layer of inter-level dielectric using photolithographic processing, said second mask, said second mask element and said second device pattern;
• etching away that part of said layer of inter-level dielectric not covered by said second photoresist mask thereby forming a clearout window in each of said alignment regions of said substrate;
• removing said second photoresist mask;
• forming a layer of second conducting material;
• and
• patterning said layer of second conducting material.