Image capturing apparatus, manufacturing method thereof, and camera
A back-side illumination image capturing apparatus includes a semiconductor substrate having a first surface for receiving incident light and a second surface located on the opposite side as the first surface, and including a photoelectric conversion portion, and a gate electrode disposed above the second surface. The apparatus further includes a first insulating layer disposed above the second surface of the semiconductor substrate, an interlayer insulation film disposed on the first insulating layer, a contact plug connected to the gate electrode, and a light-cutting portion for cutting light, of the incident light, that has passed through the photoelectric conversion portion. The light-cutting portion passes through at least part of the interlayer insulation film. The first insulating layer is located between the light-cutting portion and the semiconductor substrate.
1. A method for manufacturing a back-side illumination image capturing apparatus, the image capturing apparatus including:
a semiconductor substrate having a first surface for receiving incident light and a second surface located on the opposite side as the first surface, and including a photoelectric conversion portion, and a gate electrode located above the second surface;
a contact plug connected to the gate electrode; and
a light-cutting portion for cutting light, of the incident light, that has passed through the photoelectric conversion portion,
the method comprising:
forming a first insulating layer above the second surface of the semiconductor substrate after forming the gate electrode;
forming an interlayer insulation film above the first insulating layer;
forming a first opening for forming the contact plug by etching away part of the interlayer insulation film and part of the first insulating layer; and
forming a second opening for forming the light-cutting portion by etching away another part of the interlayer insulation film,
wherein in the step of forming the first opening, the first opening reaches the gate electrode; and
in the step of forming the second opening, at least part of the first insulating layer is left between the bottom of the second opening and the semiconductor substrate.
2. The method according to claim 1 , comprising:
forming a second insulating layer above the first insulating layer and removing part of the second insulating layer in a position where the contact plug is to be formed, before forming the interlayer insulation film;
forming, above the interlayer insulation film, a mask pattern that exposes the positions where the contact plug and the light-cutting portion are to be formed;
removing, simultaneously, a part of the interlayer insulation film from a position where the contact plug is to be formed and a part of the interlayer insulation film from a position where the light-cutting portion is to be formed by etching over the mask pattern, with the first insulating layer functioning as an etching stopper layer when etching the position where the contact plug is to be formed and the second insulating layer functioning as an etching stopper layer when etching the position where the light-cutting portion is to be formed; and
removing, simultaneously, a part of the first insulating layer from a position where the contact plug is to be formed and a part of the second insulating layer from a position where the light-cutting portion is to be formed by etching over the mask pattern, with the first insulating layer functioning as an etching stopper layer when etching the position where the light-cutting portion is to be formed.
3. The method according to claim 2 , wherein the first insulating layer and the second insulating layer each have a layered structure including a silicon oxide film and a silicon nitride film as layers.
4. The method according to claim 1 ,
wherein the semiconductor substrate further includes an element isolation region in the periphery of the photoelectric conversion portion; and
at least part of the light-cutting portion is located over the element isolation region.
5. The method according to claim 1 , wherein the light-cutting portion is a metal layer embedded in the second opening.
6. The method according to claim 1 , wherein the light-cutting portion is an air gap formed in the second opening.
7. The method according to claim 1 , further comprising:
forming a reflective layer in a position covering the light-cutting portion.
8. The method according to claim 1 , wherein the reflective layer is patterned in parallel with a step of patterning a wiring pattern connected to the contact plug.
9. The method according to claim 1 ,
wherein the reflective layer is a part of a wiring pattern connected to the contact plug.
10. The method according to claim 1 ,
wherein the light-cutting portion reflects the light that has passed through the photoelectric conversion portion.
11. The method according to claim 1 ,
wherein the light-cutting portion has a cylindrical shape extending away from the second surface of the semiconductor substrate.
12. The method according to claim 1 , wherein the light-cutting portion has a pillar shape extending away from the second surface of the semiconductor substrate.
13. A method for manufacturing a back-side illumination image capturing apparatus, the image capturing apparatus including:
a semiconductor substrate having a first surface for receiving incident light and a second surface located on the opposite side as the first surface, and including a photoelectric conversion portion, and a gate electrode located above the second surface;
a contact plug connected to the gate electrode; and
a light-cutting portion for cutting light, of the incident light, that has passed through the photoelectric conversion portion,
the method comprising:
forming a first insulating layer above the second surface of the semiconductor substrate;
forming a second insulating layer above the first insulating layer;
removing part of the second insulating layer in a position where the contact plug is to be formed,
forming an interlayer insulation film above the first and second insulating layers;
forming, above the interlayer insulation film, a mask pattern that exposes the positions where the contact plug and the light-cutting portion are to be formed;
removing, simultaneously, a part of the interlayer insulation film from a position where the contact plug is to be formed and a part of the interlayer insulation film from a position where the light-cutting portion is to be formed by etching over the mask pattern, with the first insulating layer functioning as an etching stopper layer when etching the position where the contact plug is to be formed and the second insulating layer functioning as an etching stopper layer when etching the position where the light-cutting portion is to be formed; and
removing, simultaneously, a part of the first insulating layer from a position where the contact plug is to be formed and a part of the second insulating layer from a position where the light-cutting portion is to be formed by etching over the mask pattern, with the first insulating layer functioning as an etching stopper layer when etching the position where the light-cutting portion is to be formed.