Removable sidewall spacer for lightly doped drain formation using two mask levels.

摘要

A method of using removable sidewall spacers (24) to minimize the need for mask levels in forming lightly doped drains (LDDs) (28,36) in the formation of CMOS integrated circuits. Aluminum or chemical vapor deposition (CVD) metals such as tungsten are suitable materials to form removable sidewall spacers (24) which exist around CMOS gates (18,20) during heavily doped source/drain region (30,38) implants. Conformal materials such as CVD polysilicon may also be employed for this purpose. The sidewall spacers (24) are removed before implantation of the lightly doped drain regions (28,36) around the gates (18,20). This implantation sequence is exactly the reverse of what is currently practiced for lightly doped drain (28,36) formation.