Method for making image sensor devices including a superlattice
A method for making an image sensor device may include forming a pixel region within a semiconductor substrate comprising a first dopant having a first conductivity type, forming a first pinning layer on a surface of the substrate and including a second dopant having a second conductivity type different the first conductivity type, and forming a second pinning layer in the semiconductor substrate adjacent at least one side of the pixel region and including a superlattice and the second dopant. The superlattice may include a plurality of stacked groups of layers, with each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
1 . A method for making an image sensor device comprising:
forming a pixel region within a semiconductor substrate and comprising a first dopant having a first conductivity type;
forming a first pinning layer on a surface of the substrate and comprising a second dopant having a second conductivity type different than the first conductivity type; and
forming a second pinning layer in the semiconductor substrate adjacent at least one side of the pixel region and comprising a superlattice and the second dopant, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
2 . The method of claim 1 wherein the second pinning layer extends along opposite sides of the pixel region.
3 . The method of claim 2 wherein the second pinning layer extends along a bottom of the pixel region.
4 . The method of claim 1 further comprising forming an isolation region in the semiconductor substrate adjacent the second pinning layer.
5 . The method of claim 4 wherein the second pinning layer wraps around the isolation region.
6 . The method of claim 1 wherein the first pinning layer is adjacent a first end of the pixel region; and further comprising forming a color filter layer on the substrate adjacent a second end of the pixel region opposite the first end.
7 . The method of claim 6 further comprising forming a lens on the color filter layer.
8 . The method of claim 1 further comprising:
forming a transfer gate adjacent the first pinning layer;
forming a conductive contact spaced apart from the transfer gate; and
forming a conductive via extending between the transfer gate and the conductive contact.
9 . The method of claim 1 wherein the second pinning layer further comprises fluorine.
10 . The method of claim 1 wherein the base semiconductor portion comprises silicon.
11 . The method of claim 1 wherein the at least one non-semiconductor monolayer comprises oxygen.
12 . The method of claim 1 wherein forming the pixel region comprises forming an intrinsic region, and forming a doped region including the first dopant in the intrinsic region with the intrinsic region separating the doped region and the second pinning layer.
13 . The method of claim 12 wherein the superlattice comprises a first superlattice; and wherein forming the pixel region further comprises forming a second superlattice in the intrinsic portion, the second superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
14 . The method of claim 13 wherein the second superlattice at least partially surrounds the doped region in some implementations.
15 . A method for making an image sensor device comprising:
forming a pixel region within a semiconductor substrate comprising a first dopant having a first conductivity type;
forming a first pinning layer on a surface of the substrate and comprising a second dopant having a second conductivity type different than the first conductivity type;
forming a second pinning layer in the semiconductor substrate adjacent at least one side of the pixel region and comprising a superlattice and the second dopant, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one oxygen monolayer constrained within a crystal lattice of adjacent base semiconductor portions; and
forming an isolation region in the semiconductor substrate adjacent the second pinning layer.
16 . The method of claim 15 wherein the second pinning layer extends along opposite sides and a bottom of the pixel region.
17 . The method of claim 15 wherein the second pinning layer wraps around the isolation region.
18 . The method of claim 15 wherein the first pinning layer is adjacent a first end of the pixel region; and further comprising forming a color filter layer on the substrate adjacent a second end of the pixel region opposite the first end, and a lens on the color filter layer.
19 . The method of claim 15 further comprising:
forming a transfer gate adjacent the first pinning layer;
forming a conductive contact spaced apart from the transfer gate; and
forming a conductive via extending between the transfer gate and the conductive contact.
20 . The method of claim 15 wherein the second pinning layer further comprises fluorine.
21 . A method for making an image sensor device comprising:
forming a pixel region within a semiconductor substrate comprising a first dopant having a first conductivity type;
forming a first pinning layer on a surface of the substrate and comprising a second dopant having a second conductivity type different than the first conductivity type; and
forming a second pinning layer in the semiconductor substrate adjacent at least one side of the pixel region and comprising a superlattice and the second dopant, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base silicon monolayers defining a base silicon portion, and at least one oxygen monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
22 . The method of claim 21 wherein the second pinning layer extends along opposite sides and a bottom of the pixel region.
23 . The method of claim 21 further comprising forming an isolation region in the semiconductor substrate adjacent the second pinning layer; and wherein the second pinning layer wraps around the isolation region.
24 . The method of claim 21 wherein the first pinning layer is adjacent a first end of the pixel region; and further comprising forming a color filter layer on the substrate adjacent a second end of the pixel region opposite the first end, and forming a lens on the color filter layer.
25 . The method of claim 21 further comprising:
forming a transfer gate adjacent the first pinning layer;
forming a conductive contact spaced apart from the transfer gate; and
forming a conductive via extending between the transfer gate and the conductive contact.
26 . The method of claim 21 wherein the second pinning layer further comprises fluorine.