CMOS image sensor and method for fabricating the same
View Patent ↗A Complementary Metal Oxide Semiconductor (CMOS) image sensor includes a red photodiode formed in an first epitaxial layer, an isolation layer formed with a contact region left in a partial area of the red photodiode, a green photodiode formed in a surface of the isolation layer, a contact formed in the contact region at a predetermined spatial distance from the green photodiode, a second epitaxial layer formed on the first epitaxial layer in which the green photodiode is formed, a plurality of plugs formed in the second epitaxial layer and electrically connected to the green photodiode and the contact, a device isolation film formed in a surface of the second epitaxial layer, a blue photodiode formed in a surface of the second epitaxial layer above the green photodiode, and a well region formed in the second epitaxial layer inside the plug.
1. A method comprising:
forming a red photodiode in first epitaxial layer;
forming an isolation layer in said red photodiode by ion implantation, an upper corner portion of said red photodiode being excluded from the ion implantation and becoming a contact region;
forming a green photodiode in a surface of said isolation layer;
forming at least one contact in said contact region a predetermined spatial distance from said green photodiode;
forming a second epitaxial layer over said first epitaxial layer;
forming a plurality of plugs in said second epitaxial layer for electrically connecting to said green photodiode and said contact;
forming a device isolation film in a surface of said second epitaxial layer;
forming a well region in said second epitaxial layer inside said plurality of plugs; and
forming a blue photodiode in a surface of said second epitaxial layer above said green photodiode.
2. The method of claim 1 , wherein forming said red photodiode comprises implanting N-type ions in said first epitaxial layer.
3. The method of claim 1 , wherein said N-type ions comprises at least one of phosphorous and arsenic.
4. The method of claim 1 , wherein forming said isolation layer comprises implanting conductive-type ions opposite to ions implanted to form said red photodiode.
5. The method of claim 4 , wherein said conductive type ions comprises P-type ions.
6. The method of claim 5 , wherein said P-type ions comprises boron.
7. The method of claim 1 , wherein forming said at least one contact comprises implanting the same conductive-type ions as ions implanted to form said red photodiode.
8. The method of claim 7 , wherein said conductive-type ions are implanted such that said contact region is electrically connected with said red photodiode.
9. The method of claim 1 , wherein said isolation layer insulates said red photodiode from the green photodiode.
10. The method of claim 1 , wherein said green photodiode and said at least one contact are formed simultaneously.
11. The method of claim 1 , wherein said green photodiode and said contact are formed simultaneously using N-type ion implantation.