초록 ▼

A method and apparatus are disclosed for fine aligning a photomask to a semiconductor using the interference and diffraction effects produced by coherent light impinging upon or passing through repetitive patterns on a photomask and a semiconductor. A plurality of photodetectors are employed to conv

A method and apparatus are disclosed for fine aligning a photomask to a semiconductor using the interference and diffraction effects produced by coherent light impinging upon or passing through repetitive patterns on a photomask and a semiconductor. A plurality of photodetectors are employed to convert the interference information into phase dependent electrical signals that are used to control conventional X, Y and q

대표청구항 ▼

A method for aligning a mask having first and second repetitive alignment patterns to a semiconductor wafer having corresponding first and second repetitive alignment patterns, said method comprising the steps of: (1) initially positioning the mask in superposed, spaced relation to the wafer with at

A method for aligning a mask having first and second repetitive alignment patterns to a semiconductor wafer having corresponding first and second repetitive alignment patterns, said method comprising the steps of: (1) initially positioning the mask in superposed, spaced relation to the wafer with at least a portion of each of said first and second mask alignment patterns overlying at least a portion of the corresponding first and second wafer alignment patterns; (2) illuminating the first mask alignment pattern with coherent light from a source of coherent light to produce first and second mask diffracted orders, +1M and -1M, respectively; (3) reflecting said first mask diffracted order +1M from the second wafer alignment patterns; (4) illuminating the first wafer alignment patterns with coherent light from said coherent light source to produce first and second wafer diffracted orders +1W and -1W, respectively; (5) reflecting said second wafer diffracted order -1W from the second mask alignment pattern; (6) combining said reflected mask and wafer diffracted orders +1M and -1W to produce an interference; (7) extracting the phase relationship of the +1M and -1W diffracted orders from said interference; (8) combining said mask and wafer diffracted orders -1M and +1W to produce another interference; (9) extracting the phase relationship of said diffracted orders -1M and +1W from said another interference; relatively moving said mask and wafer to produce a predetermined relationship with respect to the two extracted phase relationships.