BACKSIDE ILLUMINATED IMAGE SENSOR AND METHOD OF MANUFACTURING THE SAME
A backside illuminated image sensor includes a substrate having a frontside surface and a backside surface, a photodiode disposed in the substrate, an insulating layer disposed on the backside surface and a fixed charge layer disposed on the insulating layer. A charge accumulation region capable of being used as a backside pinning layer is formed between the photodiode and the backside surface of the substrate by the fixed charge layer.
1 . A backside illuminated image sensor comprising:
a substrate having a frontside surface and a backside surface;
a photodiode disposed in the substrate adjacent the frontside surface;
an insulating layer disposed on the backside surface of the substrate; and
a fixed charge layer disposed on the insulating layer and configured to generate a charge accumulation region between the photodiode and the backside surface.
2 . The backside illuminated image sensor of claim 1 , further comprising:
a high concentration impurity region disposed in the substrate adjacent the frontside surface and spaced apart from the photodiode; and
a gate electrode disposed on the frontside surface of the substrate between the photodiode and the high concentration impurity region.
3 . The backside illuminated image sensor of claim 1 , wherein the substrate has a first conductive type and the photodiode has a second conductive type.
4 . The backside illuminated image sensor of claim 3 , further comprising a frontside pinning layer having the first conductive type and disposed between the photodiode and the frontside surface of the substrate.
5 . The backside illuminated image sensor of claim 3 , further comprising a backside pinning layer having the first conductive type and disposed between the photodiode and the backside surface of the substrate.
6 . A backside illuminated image sensor comprising:
a substrate having a frontside surface and a backside surface;
a p-type photodiode disposed in the substrate adjacent the frontside surface;
an insulating layer disposed on the backside surface of the substrate; and
a positive fixed charge layer disposed on the insulating layer and configured to generate a charge accumulation region between the photodiode and the backside surface.
7 . The backside illuminated image sensor of claim 6 , further comprising an n-type frontside pinning layer disposed between the p-type photodiode and the frontside surface of the substrate.
8 . The backside illuminated image sensor of claim 6 , further comprising an n-type backside pinning layer disposed between the p-type photodiode and the backside surface of the substrate.
9 . The backside illuminated image sensor of claim 6 , further comprising:
a p-type high concentration impurity region disposed in a frontside surface portion of the substrate to be spaced apart from the p-type photodiode; and
a gate electrode disposed on the frontside surface of the substrate between the p-type photodiode and the p-type high concentration impurity region.
10 . The backside illuminated image sensor of claim 6 , wherein the positive fixed charge layer comprises zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride or silicon nitride.
11 . The backside illuminated image sensor of claim 6 , further comprising:
a second insulating layer disposed on the positive fixed charge layer; and
a light-blocking pattern disposed on the second insulating layer.
12 . The backside illuminated image sensor of claim 11 , further comprising:
a passivation layer disposed on the second insulating layer and the light-blocking pattern;
a color filter layer disposed on the passivation layer; and
a micro lens disposed on the color filter layer.
13 . A method of manufacturing a backside illuminated image sensor, the method comprising:
forming a photodiode in a substrate having a frontside surface and a backside surface, wherein the photodiode is formed adjacent the frontside surface;
forming an insulating layer on the backside surface of the substrate; and
forming a fixed charge layer on the insulating layer.
14 . The method of claim 13 , further comprising:
forming a gate electrode on the frontside surface of the substrate; and
forming a high concentration impurity region in the substrate, the gate electrode being disposed on the frontside surface of the substrate between the photodiode and the high concentration impurity region and configured to selectively electrically interconnect the photodiode and the high concentration impurity region.
15 . The method of claim 13 , further comprising forming a frontside pinning layer between the photodiode and the frontside surface of the substrate.
16 . The method of claim 13 , wherein the substrate has a first conductive type and the photodiode has a second conductive type.
17 . The method of claim 13 , wherein the substrate comprises an n-type epitaxial layer and the photodiode comprises a p-type impurity region formed in the n-type epitaxial layer.
18 . The method of claim 17 , wherein the fixed charge layer has a positive fixed charge.
19 . The method of claim 17 , wherein the fixed charge layer comprises zirconium oxide, hafnium silicon oxide, hafnium silicon oxynitride or silicon nitride.
20 . The method of claim 13 , further comprising:
forming a backside pinning layer in the substrate; and
back-grinding a backside surface portion of the substrate to expose a backside surface of the backside pinning layer,
wherein the photodiode is formed on a frontside surface of the backside pinning layer and the insulating layer is formed on the backside surface of the backside pinning layer.