| 摘要 |
MOS semiconductor devices of different conductivity types are formed on a semiconductor substrate using a minimal number of critical masks. Embodiments include forming conductive gates on the main surface of the semiconductor substrate, and disposable aluminum sidewall spacers on the side surfaces of the gates. A photoresist mask is then formed on gates and portions of the main surface intended to be implanted with impurities of a first conductivity type. Moderate or heavy source/drain implants of a second impurity type are then formed in the substrate, the aluminum sidewall spacers on the unmasked gates are then removed, and lightly or moderately doped source/drain extension implants of the second impurity type are formed in the substrate. The first mask is then removed and a second photoresist mask is formed on the previously uncovered gates and implanted portions of the main surface. Moderate or heavy source/drain implants with impurities of the first conductivity type are then formed, the remaining aluminum sidewall spacers are removed, and lightly or moderately doped source/drain extension implants of the first conductivity type formed. By using disposable aluminum sidewall spacers, which can be easily formed and removed without damage to other structures on the substrate or to the substrate silicon, the critical masking steps for source/drain ion implantation can be reduced to two, thereby reducing production costs and increasing manufacturing throughput.
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