Fabrication method of isolation structure photodiode

摘要

A method for fabricating a photodiode is described in which a pad oxide layer and a silicon nitride layer are sequentially formed on a provided substrate. The silicon nitride layer, and the pad oxide layer and the substrate are sequentially patterned to form an opening in the substrate. A spacer is formed on the sidewall of the opening. With the spacer and the silicon nitride layer serving as a mask, the substrate is etched forming a trench in the substrate. An oxide plug is then formed filling the trench and the opening using the conventional shallow trench fabrication method. A P-well region and an N-well region are formed respectively on two sides of the trench. An N+ type region and a P+ type region are formed respectively on two sides of the opening; wherein the N+ type region is located above the P-well region and the P+ type region is located above the N-well region