Method for forming semiconductor structure including capacitor

1 . A method for forming a semiconductor structure, comprising:

receiving a first die having a first semiconductor substrate and a first interconnection structure over the first semiconductor substrate, wherein the first semiconductor substrate has a first front-side surface and a first back-side surface, and at least a transistor is formed in the first semiconductor substrate on the first front-side surface;

forming a trench penetrating through the first back-side surface and the first front-side surface, wherein the trench exposes a portion of the first interconnection structure;

forming a capacitor structure in the trench; and

bonding a second die to the first die, wherein the second die comprises a second substrate and a second interconnection structure, and the capacitor structure is separated from the second interconnection structure,

wherein the capacitor structure has a first surface coupled to the first interconnection structure and a second surface opposite to the first surface, and a width of the first surface is less than a width of the second surface.

2 . The method of claim 1 , wherein the trench exposes a metal feature in the first interconnection structure.

3 . The method of claim 1 , further comprising forming a liner in the trench lining a sidewall of the first substrate prior to forming the capacitor structure in the trench.

4 . A method for forming a semiconductor structure, comprising:

receiving a first die having a first substrate and a first interconnection structure over the first substrate, wherein the first substrate has a front-side surface and a back-side surface;

bonding a second die to the first die, wherein the second die comprises a second substrate and a second interconnection structure over the second substrate, wherein the first interconnection structure and the second interconnection structure are disposed between the first substrate and the second substrate;

forming a first trench in the first substrate penetrating through the back-side surface and front-side surface after the bonding of the second die to the first die, wherein the first trench exposes a portion of the first interconnection structure; and

forming a capacitor structure in the first trench, wherein the capacitor structure is separated from the second interconnection structure, and the capacitor structure has a first surface coupled to the first interconnection structure and a second surface opposite to the first surface, and a width of the first surface is less than a width of the second surface.

5 . The method of claim 4 , further comprising forming a dielectric layer over the back-side surface of the first substrate prior to the forming of the first trench.

6 . The method of claim 4 , wherein the first trench exposes a metal feature in the first interconnection structure.

7 . The method of claim 6 , wherein the metal feature comprises a multiple level metal lines.

8 . The method of claim 4 , further comprising forming a liner in the first trench lining a sidewall of the first substrate prior to forming the capacitor structure in the first trench.

9 . The method of claim 4 , wherein the first substrate further comprises a first bonding structure, the second substrate further comprises a second bonding structure, and the first bonding structure is bonded to the second bonding structure.

10 . The method of claim 4 , further comprising:

forming a second trench in the first substrate penetrating through the back-side surface and front-side surface, wherein the second trench is separated from the capacitor structure; and

forming a through-substrate via (TSV) in the second trench.

11 . The method of claim 10 , wherein the second trench exposes a metal feature in the first interconnection structure.

12 . The method of claim 10 , further comprising forming a liner in the second trench lining a sidewall of the first substrate prior to forming the TSV in the second trench.

13 . The method of claim 4 , further comprising forming an image sensor structure over the second substrate, wherein the second substrate is disposed between the image sensor structure and the second interconnection structure.

14 . A method for forming a semiconductor structure, comprising:

receiving a first die having a first semiconductor substrate and a first interconnection structure over the first semiconductor substrate, wherein the first semiconductor substrate has a front-side surface and a back-side surface, and at least a transistor is formed in the first semiconductor substrate on the front-side surface;

forming a trench penetrating through the back-side surface and the front-side surface, wherein the trench exposes a portion of the first interconnection structure;

forming a capacitor structure in the trench, wherein the capacitor structure has a first surface facing the first interconnection structure and a second surface opposite to the first surface, and the first surface is lower a top surface of the first interconnection structure, and a width of the first surface is less than a width of the second surface; and

bonding a second die to the first die, wherein the second die comprises a second substrate and a second interconnection structure over the second substrate, wherein the first semiconductor substrate and the second interconnection structure are disposed between the first interconnection structure and the second substrate.

15 . The method of claim 14 , further comprising forming a first bonding structure over the capacitor structure, wherein the first bonding structure is bonded to a second bonding structure of the second die.

16 . The method of claim 14 , further comprising forming a TSV in the first die, wherein the TSV penetrates through the back-side surface and the front-side surface, and is separated from the capacitor structure.

17 . The method of claim 16 , further comprising forming a first bonding structure over the TSV and the capacitor structure, wherein the first bonding structure is bonded to a second bonding structure of the second die.

18 . The method of claim 16 , wherein the forming of the TSV is performed after the forming of the capacitor structure.

19 . The method of claim 14 , further comprising bonding a third die to the first die prior to the forming of the trench.

20 . The method of claim 19 , further comprising forming an image sensor structure over the third die after the bonding of the second die to the first die.