FABRICATION METHOD OF SEMICONDUCTOR DEVICE

摘要

PURPOSE: A forming method of a twin well in a semiconductor device is provided to prevent a latch up appearance and an irregular profile of a mask layer. CONSTITUTION: At first, a thick oxide layer(20) is formed on an overall surface of a semiconductor substrate(10), and then the oxide layer(20) above a prearranged region for an n-well(40) is mostly etched by a photomasking technology. Next, while the partly etched oxide layer(20) is used as an implant mask, n-type dopants are implanted into the substrate(10) at higher energy to form the n-well(40). Then, another photoresist layer is deposited on an overall surface of the oxide layer(20), and then etched by chemical mechanical polishing to expose a non-etched portion of the oxide layer(20). The exposed oxide layer(20) is then mostly etched by using the partly etched photoresist layer(50A) as an etch mask. While the photoresist layer(50A) is also used for a subsequent p-type dopants implantation, a p-well(60) is formed in the substrate(10).