Operational amplifier based test structure for transistor threshold voltage variation

A new test structure has been developed, which is comprised of MOSFET arrrays and an on-chip operational amplifier feedback loop for measuring threshold voltage variation. The test structure also includes an on-chip clock generator and address decoders to scan through the arrays. It can be used in an inline test environment to provide rapid assessment of Vt variation for technology development and chip manufacturing. Hardware results in a 65nm technology are presented.