Inverse source/drain process using disposable sidewall spacer

摘要

The present invention discloses an inverse source/drain process using disposable sidewall, for forming an LDD MOSFET device on a semiconductor substrate, comprises the following steps: forming a gate electrode on the semiconductor substrate; forming a disposable sidewall spacer adjacent to each of opposite sides of the gate electrode; implanting a heavy dose of a dopant into the semiconductor substrate to form a heavily doped region; removing the disposable sidewall spacer; and implanting a light dose of a dopant into the semiconductor substrate to form a lightly doped region. The present invention employs the disposable sidewall spacer to accomplish the inverse-sequence ion-implantation steps so as to greatly reduce the transient enhanced diffusion (TED) caused by the ion implantation with a heavy dose. As a result, the present invention achieves the ultra-shallow junction applicable to submicron MOS device.