Image sensor having 3-dimensional transfer transistor and its method of manufacture

A method of manufacturing an image sensor, the method comprising:

• defining a first active region, a second active region extending from the first active region, and sidewalls of the second active region by forming an isolation layer in a semiconductor substrate;
• forming a transfer gate electrode on the second active region, the transfer gate electrode being configured to cover both of the sidewalls of the second active region so that a portion of the transfer gate electrode overlaps with the first active region, and to have a recessed portion at a boundary of the first and second active regions, the recessed portion having a recess opening and extending from the recess opening towards the second active region to expose a portion of the second active region, wherein the recessed portion is aligned with a center of the transfer gate electrode;
• forming an n-photodiode photoresist pattern on the semiconductor substrate having the transfer gate electrode, wherein the n-photodiode photoresist pattern includes an opening exposing the first active region and the recessed portion;
• forming a deep n-impurity region by implanting n-type impurity ions into the first and second active regions by using the n-photodiode photoresist pattern as an ion implantation mask, wherein the deep n-impurity region includes a protrusion disposed in the second active region;
• forming a shallow p-impurity region at an upper portion of the deep n-impurity region by implanting p-type impurity ions into the first active region;
• and
• forming a floating diffusion region by implanting n-type high concentration impurity ions into the second active region at a position spaced apart from the shallow p-impurity region.