Impact on Latchup Immunity due to the Switch From Epitaxial to Bulk Substrate

A comparison of the guardring efficiency is done between the epitaxial silicon and bulk silicon for sub-quarter micron technology. The dose optimization and use of ultra high-energy boron buried implanted layer (HBIL) after both pad oxidation and sacrificial oxidation process stage to enhance the guardring efficiency performance of bulk wafers are also investigated. The results and mechanisms leading to such phenomena are discussed.