Image sensor having photo diode and method for manufacturing the same

An image sensor having a semiconductor substrate, a transfer gate and reset gate formed on predetermined portions of the semiconductor substrate with a specific distance therebetween, a photo diode region formed on one side of the transfer gate, a common source region formed between the transfer gate and the reset gate, and a drain region of the reset transistor formed on the other side of the reset gate, wherein the photo diode region comprises:

• a p-type photo diode region formed on the surface of the photo diode region of the semiconductor substrate;
• a first n-type photo diode region underneath the p-type photo diode region, contacting an interface of the p-type photo diode region;
• and
• a second n-type photo diode region surrounding the first n-type photo diode region,
• wherein impurities composing the first n-type photo diode region have smaller projection distance and diffusivity than impurities composing the second n-type photo diode region.

A method for manufacturing an image sensor having a photo diode, comprising the acts of:

• forming a transfer gate and a reset gate on predetermined portions of a semiconductor substrate with a specific distance therebetween;
• forming a photoresist pattern exposing a region at one side of the transfer gate;
• forming a p-type photo diode region by implanting p-type impurities into the exposed semiconductor substrate with a first ion implantation energy;
• forming a first n-type photo diode region by implanting first n-type impurities into a portion below the p-type photo diode region, with a second ion implantation energy;
• forming a second n-type photo diode region by implanting second n-type impurities into a portion surrounding the first n-type photo diode region, with a third ion implantation energy;
• and
• removing the photoresist pattern.