Cmos image sensor and method for manufacturing the same

Abstract

A CMOS image sensor and method for fabricating same are provided. The CMOS image sensor can include a gate electrode formed on an active area of a first conductive type semiconductor substrate, on which a photodiode area and a transistor area are defined; a low-density second conductive type diffusion region formed on the photodiode area at a first side of the gate electrode; a high-density second conductive the diffusion region formed on the transistor area at a second side of the gate electrode; an insulating layer formed on the semiconductor substrate at both sides of the gate electrode with a thickness less than a thickness of the gate electrode, but greater than a thickness of a gate insulating layer; and insulating layer sidewalls formed on the insulating layer at both sides of the gate electrode.

1 . A CMOS image sensor comprising:
 a gate electrode formed on an active area of a first conductive semiconductor substrate, with a gate insulating layer interposed therebetween;   a low-density second conductive diffusion area formed on a photodiode area at a first side of the gate electrode;   a high-density second conductive diffusion area formed on a transistor area at a second side of the gate electrode;   an insulating layer formed on the semiconductor substrate at both sides of the gate electrode, wherein the insulating layer has a thickness less than a thickness of the gate electrode and larger than a thickness of the gate insulating layer; and   insulating layer sidewalls formed on the insulating layer at both sides of the gate electrode.   
   
   
       2 . The CMOS image sensor as claimed in  claim 1 , wherein the insulating layer has a thickness about 50% of the thickness of the gate electrode. 
   
   
       3 . The CMOS image sensor as claimed in  claim 1 , wherein the insulating layer sidewall comprises oxide. 
   
   
       4 . The CMOS image sensor as claimed in  claim 1 , comprising a first conductive epitaxial layer between the first semiconductor substrate and the low-density second conductive diffusion area. 
   
   
       5 . The CMOS image sensor as claimed in  claim 4 , wherein the first conductive epitaxial layer is formed between the first semiconductor substrate and the a high-density second conductive diffusion area. 
   
   
       6 . The CMOS image sensor as claimed in  claim 4 , wherein the first conductive epitaxial layer and the low-density second conductive diffusion area form a photodiode. 
   
   
       7 . The CMOS image sensor as claimed in  claim 6 , wherein the first conductive epitaxial layer and the low-density second conductive diffusion area form a depletion region. 
   
   
       8 . The CMOS image sensor as claimed in  claim 1 , the insulating layer covers the low-density second conductive diffusion area. 
   
   
       9 . The CMOS image sensor as claimed in  claim 1 , the insulating layer covers the high-density second conductive diffusion area.