Solid-state imaging device and method for manufacturing same
In a back-illuminated solid-state imaging device, a multilayer interconnect layer, a semiconductor substrate, a plurality of color filters, and a plurality of microlenses are provided in this order. A p-type region is formed so as to partition a lower portion of the semiconductor substrate into a plurality of regions, and an insulating member illustratively made of BSG is buried immediately above the p-type region. PD regions are isolated from each other by the p-type region and the insulating member. Moreover, a high-concentration region is formed in a lower portion of the PD region, and an upper portion is served as a low-concentration region.
1. A solid-state imaging device comprising:
an interconnect structure; and
a semiconductor substrate provided on the interconnect structure, the semiconductor substrate including:
a first-conductivity-type region formed so as to partition a lower portion of the semiconductor substrate into a plurality of regions; and
an insulating member made of an insulating material and buried in a region immediately above the first-conductivity-type region,
the semiconductor substrate being irradiated with light from its upper surface side;
a high-concentration region of a second conductivity type formed in a lower portion of a region partitioned by the first-conductivity-type region and the insulating member; and
a low-concentration region of the second conductivity type provided immediately above the high-concentration region and having a lower effective impurity concentration than the high-concentration region, and
the insulating member has a lower surface which is located above an interface between the high-concentration region and the low-concentration region.
2. The device according to claim 1 , wherein a material constituting the insulating member has a lower transmittance to visible light than a material constituting the low-concentration region.
3. The device according to claim 1 , wherein a material constituting the insulating member has a lower refractive index than a material constituting the low-concentration region.
4. The device according to claim 1 , wherein the semiconductor substrate is formed from silicon, and the insulating member is formed from silicon oxide doped with at least one of boron and phosphorus.
5. The device according to claim 1 , wherein the semiconductor substrate further includes another first-conductivity-type region enclosing the insulating member.
6. The device according to claim 1 , wherein the insulating member is shaped like a lattice as viewed in a direction perpendicular to the upper surface of the semiconductor substrate.
7. The device according to claim 1 , wherein in a direction perpendicular to the upper surface of the semiconductor substrate, the low-concentration region has a uniform impurity concentration profile, and the high-concentration region has an impurity concentration profile with a peak.
8. The device according to claim 1 , further comprising:
a color filter placed above the semiconductor substrate for each of the partitioned regions; and
a microlens placed above the semiconductor substrate for each of the partitioned regions.