Image sensor and method for fabricating the same

DETAILED DESCRIPTION OF THE INVENTION FIG.
3 is a plane view showing a complementary metal-oxide semiconductor device (hereinafter referred as to CMOS) image sensor in accordance with a first preferred embodiment of the present invention.
The-CMOS image sensor shown in FIG.
3 includes a photodiode area (hereinafter referred as to PD), a gate electrode of a transfer transistor Tx and a floating diffusion area (hereinafter referred as to FD).
On a predetermined place of a substrate 21, an active area including the PD, the FD having a smaller area than the PD and a channel area ch having a bottle-neck structure that connects the PD and the FD is formed.
Then, a field oxide layer 26 for isolating electrically the active area is formed.
A field stop layer 25 having a greater area than the field oxide layer 26 as being extended towards the active area with a first predetermined distance is formed beneath the field oxide layer 26.
Also, a gate electrode 27 having one side superposed entirely on one side of the PD connected to the channel area ch with a second predetermined distance and the other side aligned to the FD is formed on the substrate 21.
Herein, the gate electrode also covers the channel area ch.
In the mean time, the PD includes an n- diffusion area 29 formed by being self-aligned to the field stop layer 25 and the one side of the gate electrode 27 of the transfer transistor Tx and a p0 diffusion area 31 formed in the n- diffusion area 29 by being self-aligned to the field stop layer 25 with a predetermined distance from the one side of the gate electrode 27.
Meanwhile, an n+ diffusion layer 33 is formed at the other side of the gate electrode 27.
FIGS.
4A to 4E are cross-sectional views illustrating a process for fabricating the CMOS image sensor with respect to an I-I′ line of FIG.
3.
Also, FIGS.
5A to 5D are plane views illustrating a process for fabricating the CMOS image sensor with respect to the I-I′ line of FIG.
3.
With reference to FIGS.
4A to 4E and FIGS.
5A to 5D, the process for forming the CMOS image sensor with respect to the I-I′ line of FIG