Abstract: The method for in-line monitoring a wafer is described as follows. A wafer is provided, and at least one inspection structure is then formed on the wafer in the following steps. An N-well region and a P-well region are formed in the wafer, wherein the N-well region and the P-well region are separated from each other. A gate on each of the N-well region and the P-well region is formed. A P-type doped region is respectively formed in the N-well region and in the P-well region at both sides of the gates. A first contact plug is formed on each P-type doped region, and second contact plug is formed on each gate. Afterwards, a defect inspection is conducted utilizing an electron beam inspection (EBI) system, such that a short between each first contact plug and each gate is determined.

Abstract: A trench isolation structure for high voltage device is provided including a high voltage well, a low voltage well, and trench oxide. The high voltage well is formed first to be the deep junction isolation of isolation region. Next, the trench oxide isolation is formed overlying the high voltage well. Then, the low voltage well with higher concentration is formed underlying the trench oxide by using high energy implant. The isolation structure is a trench oxide(dielectric isolation)-junction isolation structure.