Mask alignment methods
Abstract
Abstract IN MAKING SEMICONDUCTIVE DEVICES, IT IS NECESSARY TO SEPARATE GROUPS OF CIRCUIT ELEMENTS FORMED ON THE FACE OF A SEMICONDUCTIVE WAFER BY ETCHING FROM THE BACKSIDE OF THE WAFER. TO DO THIS A LAYER OF PHOTORESIST IS APPLIED TO THE BACKSIDE OF THE WAFER, A SEPARATION MASK IS POSITIONED ON THE PHOTORESIST LAYER AND INTERSECTING GRID LINES OF THE MASK ARE ALIGNED WITH THE WAFER MATERIAL LYING BETWEEN THE GROUPS OF CIRCUIT ELEMENTS. THE ALIGNMENT IS ACCOMPLISHED BY FORMING A PLURALITY OF HOLES, PREFERABLY WITH A LASER, PARTIALLY THROUGH THE WAFER AT ALIGNMENT REFERENCES ON THE FACE OF THE WAFER. THEN, A PORTION OF THE BACKSIDE OF THE WAFER IS REMOVED TO JOIN THE HOLES TO THE BACKSIDE. NEXT, THE PHOTORESIST LAYER IS FORMED ON THE BACKSIDE OF THE WAFER SO THAT THE HOLES REMAIN DISTINGUISHABLE AND THE MASK IS POSITIONED ON THE PHOTORESIST LAYER AND ALIGNED WITH THE HOLES. THE INVENTION IS PARTICULARLY USEFUL IN FABRICATING INTEGRATED CIRCUITS HAVING A MAGNETIC LAYER FORMED ON THE INACTIVE SIDES THEREOF.
Inventors
- 👤 D Walls
Bibliographic Details
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