METHOD FOR MANUFACTURING OF SEMICONDUCTOR DEVICE

摘要

A method for manufacturing a semiconductor device is provided to simplify a well forming process and to improve manufacture yield by simultaneously forming an N-well and an N-drift region. A P-type impurity is selectively implanted into an N-type substrate(111). An N-type impurity is selectively implanted into the N-type substrate where the P-type impurity is implanted. A P-type impurity region is diffused downwardly into the upper region by diffusing the P-type impurity and the N-type impurity implanted into an upper region of the N-type substrate at the same time. P-drifts(113a,113b,114) and P-wells(115,116) of a high voltage device and a P-well(127) of a low voltage device are formed in the P-type impurity region. An N-type impurity region is diffused downward the upper region. The N-type impurity region is formed thinner than the P-type impurity region. An N-drift region and an N-well region of the high voltage device and an N-well(118) of the low voltage device are formed in an N-type impurity region. Impurities for controlling a threshold voltage are ion-implanted into channel parts of the high voltage device and the low voltage device. A gate oxide is formed on the high voltage device and the low voltage device. A gate electrode is formed on the gate oxide.