Method of Manufacturing Complementary Metal Oxide Semiconductor Image Sensor

Abstract

A method of manufacturing a complementary metal oxide semiconductor (CMOS) image sensor is provided. The method can include the steps of: providing a semiconductor substrate having an active region and an isolation region defined thereon; forming a photodiode at a photodiode area of the active region; forming first and second gate polys on a transistor region of the active region; forming a floating diffusion region on the semiconductor substrate between the first and second gate polys for receiving electrons transferred from the photodiode; and forming a floating diffusion node region at a part of the floating diffusion region for forming a metal contact. The floating diffusion region can be formed independently of the floating diffusion node region, so that a junction leakage current generated from the floating diffusion node region can be controlled.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram illustrating a 4T-type complementary metal oxide semiconductor (CMOS) image sensor including one photodiode and four transistors.

FIG. 2 is layout view showing a unit pixel of a conventional 4T-type CMOS image sensor.

FIG. 3 is a sectional view illustrating the conventional 4T type CMOS image sensor.

FIG. 4 is a layout view illustrating a unit pixel of a CMOS image sensor according to an embodiment of the present invention.

FIG. 5 is a sectional view illustrating a CMOS image sensor according to an embodiment of the present invention.

Claims

1. A method of manufacturing a complementary metal oxide semiconductor (CMOS) image sensor, comprising: providing a semiconductor substrate having an isolation layer formed thereon;forming a photodiode on an active region of the semiconductor substrate;forming first and second gate polys on a transistor region of the active region of the semiconductor substrate;forming a floating diffusion region on the semiconductor substrate between the first and second gate polys for receiving electrons transferred from the photodiode; andforming a floating diffusion node region at part of the floating diffusion region for forming a metal contact.

2. The method according to claim 1, wherein: the first gate poly is a gate poly of a transfer transistor of a CMOS image sensor; andthe second gate poly is a gate poly of a reset transistor of the CMOS sensor.

3. The method according to claim 1, wherein forming the floating diffusion region comprises implanting n type impurity ions.

4. The method according to claim 3, wherein forming the floating diffusion region further comprises implanting p type impurity ions into a surface of the floating diffusion region after implanting the n type impurity ions.

5. The method according to claim 4, wherein forming the floating diffusion node region comprises implanting n+ type impurity ions to a higher density than impurities implanted into the floating diffusion region.

6. A method of manufacturing a complementary metal oxide semiconductor (CMOS) image sensor, comprising: providing a semiconductor substrate having an isolation region and an active region defined thereon;forming a plurality of gate polys at a predetermined portion of the active region;forming a photodiode on the semiconductor substrate at one side of one of the plurality of gate polys;forming spacers on sidewalls of the gate polys;implanting n0 type impurity ions for defining a floating diffusion region in the active region using a first mask covering the photodiode and exposing a region between two of the plurality of gate polys;implanting p0 type impurity ions into a surface of the floating diffusion region using the first mask; andimplanting n+ type impurity ions for forming a the floating diffusion node region for a metal contact at a part of the floating diffusion region using a second mask exposing only the part of the floating diffusion region.