Title :
Automatic mask alignment without a microscope
Author :
Kanjilal, Alok Kumar ; Narain, Ram ; Sharma, Rina ; Chitnis, Vijay T. ; Singh, Brahm Pal ; Liu, Jingnan ; Yamada, Jun ; Uchida, Yoshiyuki
Author_Institution :
Stand. Div., Nat. Phys. Lab., New Delhi, India
fDate :
6/1/1995 12:00:00 AM
Abstract :
A novel method for automatic mask alignment without using a microscope is reported. This method relies on the moire technique, and alignment marks are used in the form of gratings. The alignment is done in two steps with coarse and fine pitch gratings. The mask-to-wafer placement accuracy is estimated to be ±40 μm. The mask alignment accuracy with present experimental conditions is demonstrated to be better than ±50 nm. New alignment marks for the actual mask aligner are also proposed
Keywords :
integrated circuit technology; masks; semiconductor technology; IC fabrication; automatic mask alignment; coarse pitch gratings; fine pitch gratings; gratings; mask-to-wafer placement accuracy; moire technique; Costs; Energy consumption; Equations; Error correction; Gratings; Instruments; Laser beams; Microcomputers; Microscopy; Signal generators;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
