Solid-state image sensing device manufacturing method and solid-state image sensing device

1. A solid-state image sensing device manufacturing method comprising:

forming a photoelectric converting element, a diffusion layer included in a floating diffusion, and a read transistor, in a photoelectric converting element formation region of a semiconductor substrate, a floating diffusion formation region, and a read transistor formation region located between the photoelectric converting element formation region and the floating diffusion formation region, respectively; and

forming a first semiconductor layer including a first impurity on the diffusion layer on a first surface of the semiconductor substrate; and

conducting a heat treatment after the first semiconductor layer is formed,

wherein after the heat treatment, the concentration of a metal impurity in the floating diffusion formation region is higher than the concentration of a metal impurity in the photoelectric converting element formation region.

2. The solid-state image sensing device manufacturing method according to claim 1 , wherein

a metal impurity in the semiconductor substrate is moved into the first semiconductor layer by the heat treatment.

3. The solid-state image sensing device manufacturing method according to claim 1 , wherein

the concentration of a metal impurity in the first semiconductor layer is higher than the concentration of a metal impurity in the diffusion layer.

4. The solid-state image sensing device manufacturing method according to claim 1 , further comprising:

removing the first semiconductor layer after the heat treatment.

5. The solid-state image sensing device manufacturing method according to claim 4 , further comprising:

removing an impurity region including a metal impurity in a boundary between the diffusion layer and the first semiconductor layer, and setting back the upper surface of the diffusion layer to a second surface opposite to the first surface of the semiconductor substrate, during the removal of the first semiconductor layer.

6. The solid-state image sensing device manufacturing method according to claim 1 , further comprising:

forming a silicide layer on a gate electrode of the read transistor and on the first semiconductor layer; and

forming, via the silicide layer, a contact portion to be connected to the first semiconductor layer and the floating diffusion including the diffusion layer, respectively.

7. The solid-state image sensing device manufacturing method according to claim 1 , further comprising:

forming a first transistor in a first region adjacent to the floating diffusion formation region simultaneously with the formation of the read transistor; and

forming a second semiconductor layer including the same material as the first semiconductor layer on a source/drain diffusion layer of the first transistor simultaneously with the formation of the first semiconductor layer.

8. The solid-state image sensing device manufacturing method according to claim 1 , further comprising:

forming an interlayer insulating film on the first surface of the semiconductor substrate after the first semiconductor layer is formed.

9. The solid-state image sensing device manufacturing method according to claim 1 , wherein

the first semiconductor layer includes a gettering site generated by the first impurity.

10. The solid-state image sensing device manufacturing method according to claim 1 , wherein

the first semiconductor layer is formed by a silicon layer including at least one of phosphorus, germanium, and carbon as the first impurity.

11. The solid-state image sensing device manufacturing method according to claim 1 , wherein

the first semiconductor layer is formed by epitaxial growth, and a crystal defect as a gettering site is formed in the first semiconductor layer.