CMOS circuit production process involves self-aligned oxide mask formation

摘要

In a CMOS circuit production process, an oxide mask is formed by thermally oxidation to form a silicon oxide layer of thickness which is greater above n-doped silicon than above undoped silicon and insulating material, followed by back-etching to form an oxide mask which covers n-doped source/drain regions. CMOS circuit production process comprises (a) forming the respective p-channel and n-channel MOS transistor gate dielectrics and gate electrodes provided with insulating sidewall spacers; (b) covering the p-channel MOS transistor active region and then forming n-doped regions in the n-channel MOS transistor active region; (c) thermally oxidizing to form a silicon oxide layer of thickness which is greater above the n-doped silicon material than above the undoped silicon and the insulating material; (d) back-etching the silicon oxide layer to expose the semiconductor substrate surface at the sides of the gate electrode in the p-channel MOS transistor active region and simultaneously forming an oxide mask which covers the n-doped source/drain regions; and (e) forming the source/drain regions of the p-channel and n-channel MOS transistors.