Shallow junction formation and high dopant activation rate of MOS devices

摘要

A method for forming a semiconductor structure includes providing a semiconductor substrate; forming a gate stack over the semiconductor substrate; implanting carbon into the semiconductor substrate; and implanting an n-type impurity into the semiconductor substrate to form a lightly doped source/drain (LDD) region, wherein the n-type impurity comprises more than one phosphorous atom. The n-type impurity may include phosphorous dimer or phosphorous tetramer.