METHOD FOR FABRICATING METAL OXIDE SEMICONDUCTOR TRANSISTOR

摘要

PURPOSE: A method for fabricating a metal oxide semiconductor(MOS) transistor is provided to prevent a threshold voltage characteristic of the MOS transistor from being deteriorated by erroneous implantation of p-type impurity ions by depositing polycrystalline silicon doped with the p-type impurity ions to form a gate. CONSTITUTION: A field oxide layer(2) is formed on a part of a substrate(1) to define an active region. Impurity ions are selectively implanted into each active region to form a p-type well(3) and an n-type well(4). A gate oxide layer(5), a p-type polycrystalline silicon(6) and an oxide layer(12) are deposited on the p-type well and the n-type well. The oxide layer and the p-type polycrystalline silicon are patterned to form a gate on the p-type well and the n-type well through a photolithography process. A sidewall(9) is formed on the side surface of the gate. Photoresist(P/R1) is applied to the upper surface of the gate and is exposed and developed to make a photoresist(P/R1) pattern left on the n-type well. A source/drain is formed on the p-type well exposed to the side surface of the sidewall through an As+ implantation process using the photoresist(P/R1) pattern as an ion implantation mask. The gate formed on the p-type well is doped with n-type impurities. After the photoresist(P/R1) pattern is removed, photoresist(P/R1) is applied again and exposed/developed to form a photoresist(P/R1) pattern positioned on the p-type well. BF2+ is selectively implanted into only the n-type well to form a p-type source/drain through an ion implantation process.