Elevated photodiode with a stacked scheme

1. A semiconductor device comprising:

a first semiconductor die comprising a first semiconductor substrate;

a second semiconductor die bonded to the first semiconductor die; and

a pixel unit disposed in both the first semiconductor die and the second semiconductor die, the pixel unit comprising:

a storage node in the first semiconductor substrate;

a photodiode over and electrically connected to the storage node; and

read out circuitry, wherein the storage node is interposed between the photodiode and the read out circuitry.

2. The semiconductor device of claim 1 further comprising an isolation structure extending from a first surface of the first semiconductor substrate to a second surface of the first semiconductor substrate, wherein the isolation structure encircles a region of the first semiconductor substrate, and wherein the storage node is disposed in the region of the first semiconductor substrate.

3. The semiconductor device of claim 2 , wherein the isolation structure extends above the region of the first semiconductor substrate in which the storage node is disposed.

4. The semiconductor device of claim 2 , wherein the isolation structure extends to a top electrode of the photodiode.

5. The semiconductor device of claim 1 wherein the photodiode comprises:

a bottom electrode over and electrically connected to the storage node;

a photoelectrical conversion layer over the bottom electrode; and

a top electrode over the photoelectrical conversion layer.

6. The semiconductor device of claim 1 , wherein the second semiconductor die comprises a second semiconductor substrate, and wherein the read out circuitry comprises active devices disposed at a surface of the second semiconductor substrate.

7. The semiconductor device of claim 6 , wherein the read out circuitry is electrically connected to the storage node by a first interconnect structure of the first semiconductor die and a second interconnect structure of the second semiconductor die, and wherein the first interconnect structure and the second interconnect structure are both disposed between the first semiconductor substrate and the second semiconductor substrate.

8. The semiconductor device of claim 7 , wherein a first contact pad of the first interconnect structure is in physical contact with a second contact pad of the second interconnect structure at an interface between the first semiconductor die and the second semiconductor die.

9. The semiconductor device of claim 1 , the pixel unit further comprises:

a color filter over the photodiode; and

a microlens over the color filter.

10. A semiconductor device comprising:

a first semiconductor substrate, the first semiconductor substrate comprising:

a first region having a first height; and

a second region having a second height greater than the first height; and

a pixel unit comprising a photodiode, the photodiode comprising:

a bottom electrode overlying the first region of the first semiconductor substrate;

a photoelectrical conversion layer overlying the bottom electrode; and

a transparent top electrode overlying the photoelectrical conversion layer.

11. The semiconductor device of claim 10 , wherein the bottom electrode is in direct contact with a storage node of the pixel unit, the storage node is disposed in the first region of the first semiconductor substrate.

12. The semiconductor device of claim 11 , wherein the pixel unit comprises:

a transfer gate transistor at a top surface of the first semiconductor substrate; and

a floating diffusion region in the first region of the first semiconductor substrate, wherein the transfer gate transistor electrically interconnects and disconnects the storage node and the floating diffusion region.

13. The semiconductor device of claim 10 further comprising an isolation structure separating the first region of the first semiconductor substrate from the second region of the first semiconductor substrate.

14. The semiconductor device of claim 13 , wherein the transparent top electrode of the photodiode overlies the isolation structure and the second region of the first semiconductor substrate.

15. The semiconductor device of claim 10 further comprising:

a second semiconductor substrate bonded to the first semiconductor substrate; and

metallization layers connecting devices within the second semiconductor substrate to devices within the first semiconductor substrate.

16. A package comprising:

a color filter located over a first semiconductor substrate;

a photodiode located between the color filter and the first semiconductor substrate;

first metallization layers electrically connecting the photodiode to a first contact pad;

a second contact pad directly bonded to the first contact pad;

second metallization layers electrically connecting the second contact pad to active devices within a second semiconductor substrate different from the first semiconductor substrate, wherein the active devices are electrically interconnected to provide read out circuitry; and

an isolation structure extending through the first semiconductor substrate, wherein an electrode of the photodiode is interposed between the isolation structure and the color filter.

17. The package of claim 16 , wherein the photodiode comprises:

a bottom electrode over the first semiconductor substrate;

a photoelectrical conversion layer over the bottom electrode; and

a top electrode over the photoelectrical conversion layer.

18. The package of claim 17 , wherein the bottom electrode physically contacts a storage node in the first semiconductor substrate.

19. The package of claim 17 , wherein the bottom electrode is disposed at a lower level than a surface of the first semiconductor substrate, the surface of the first semiconductor substrate is in a region of the first semiconductor substrate separated from a storage node by the isolation structure.

20. The package of claim 19 , wherein the isolation structure surrounds the photodiode.