Semiconductor structure and manufacturing methodthereof

Abstract

A semiconductor structure and its manufacturing method are disclosed. The semiconductor structure includes a substrate, a photodiode, a dielectric layer, a first contact window, a second contact window, an interconnect layer, and a barrier layer. The photodiode is disposed on the substrate and includes a first doped semiconductor layer within the substrate, a second doped semiconductor layer on top of the first doped semiconductor layer, and an undoped semiconductor layer between the first and second doped semiconductor layers, wherein the first and second doped semiconductor layers have opposite conductivity types. The dielectric layer is disposed on the substrate and covers the photodiode. The first contact window is disposed in the dielectric layer, above the second doped semiconductor layer, and electrically connected to the second doped semiconductor layer. The second contact window is disposed in the dielectric layer and electrically connected to the first doped semiconductor layer. The interconnect layer is disposed on the dielectric layer and electrically connected to both the first and second contact windows. The barrier layer is disposed between the interconnect layer and the dielectric layer. The barrier layer located above the photodiode is discontinuous.

Claims

1. A semiconductor structure, comprising: Base; A photodiode, disposed on the substrate, includes a first doped semiconductor layer in the substrate, a second doped semiconductor layer on the first doped semiconductor layer, and an undoped semiconductor layer between the first and second doped semiconductor layers, wherein the first and second doped semiconductor layers have opposite conductivity types; a dielectric layer disposed on the substrate and covering the photodiode; a first contact window disposed in the dielectric layer, above the second doped semiconductor layer, and electrically connected to the second doped semiconductor layer; a second contact window disposed in the dielectric layer and electrically connected to the first doped semiconductor layer; an interconnect layer disposed on the dielectric layer and electrically connected to the first and second contact windows; and a first barrier layer disposed between the interconnect layer and the dielectric layer, wherein the first barrier layer directly above the photodiode is discontinuous and the interconnect layer is continuous.

2. The semiconductor structure as claimed in claim 1, wherein the undoped semiconductor layer comprises an undoped germanium layer or an undoped silicon-germanium layer.

3. The semiconductor structure as claimed in claim 1, wherein the first doped semiconductor layer is exposed at the surface of the substrate.

4. The semiconductor structure as claimed in claim 3, wherein the first doped semiconductor layer is part of the substrate.

5. The semiconductor structure as claimed in claim 1, wherein the second doped semiconductor layer is a doped amorphous silicon layer.

6. The semiconductor structure of claim 1, wherein the first barrier layer is located between the second contact window and the dielectric layer, between the second contact window and the first doped semiconductor layer, between the interconnect layer and the dielectric layer, and between the interconnect layer and the first contact window, and exposes the dielectric layer directly above the photodiode.

7. The semiconductor structure as claimed in claim 6, wherein the interconnect layer contacts the dielectric layer directly above the photodiode.

8. The semiconductor structure of claim 1 further includes a second barrier layer disposed between the first contact window and the dielectric layer and between the first contact window and the second doped semiconductor layer.

9. The semiconductor structure of claim 8, wherein the light reflectivity of the interconnect layer is greater than the light reflectivity of the first barrier layer and the second barrier layer.

10. The semiconductor structure of claim 9, wherein the material of the interconnect layer comprises aluminum, and the first barrier layer is composed of a titanium layer and a titanium nitride layer.

11. The semiconductor structure as claimed in claim 1 further includes a third barrier layer disposed on the interconnect layer.

12. A method for manufacturing a semiconductor structure, comprising: Provide a base; A photodiode is formed on a substrate, wherein the photodiode includes a first doped semiconductor layer in the substrate, a second doped semiconductor layer on the first doped semiconductor layer, and an undoped semiconductor layer between the first doped semiconductor layer and the second doped semiconductor layer, wherein the first doped semiconductor layer and the second doped semiconductor layer have opposite conductivity types; a dielectric layer is formed on the substrate, wherein the dielectric layer covers the photodiode; a first contact window is formed in the dielectric layer, wherein the first contact window is located above the second doped semiconductor layer and electrically connected to the second doped semiconductor layer; a second contact window is formed in the dielectric layer, wherein the second contact window is electrically connected to the first doped semiconductor layer; an interconnect layer is formed on the dielectric layer, wherein the interconnect layer is electrically connected to the first contact window and the second contact window; and a first barrier layer is formed between the interconnect layer and the dielectric layer, wherein the first barrier layer directly above the photodiode is discontinuous and the interconnect layer is continuous.

13. A method of manufacturing a semiconductor structure as claimed in claim 12, wherein the first doped semiconductor layer is exposed on the surface of the substrate.

14. A method of manufacturing a semiconductor structure as claimed in claim 13, wherein the method of forming the first doped semiconductor layer includes implanting a dopant into the substrate.

15. A method of manufacturing a semiconductor structure as claimed in claim 12, wherein the first barrier layer is located between the second contact window and the dielectric layer, between the second contact window and the first doped semiconductor layer, between the interconnect layer and the dielectric layer, and between the interconnect layer and the first contact window, and exposes the dielectric layer directly above the photodiode.

16. A method for manufacturing a semiconductor structure as claimed in claim 15, wherein the method for forming the first barrier layer, the second contact window, and the interconnect layer comprises: A contact window opening is formed in the dielectric layer, wherein the contact window opening exposes the first doped semiconductor layer; A first barrier material layer is conformally formed on the dielectric layer; a portion of the first barrier material layer is removed to expose the dielectric layer directly above the photodiode; a conductive layer is formed on the dielectric layer, wherein the conductive layer fills the contact window opening; The conductive layer and the first barrier layer material layer on the top surface of the dielectric layer are patterned to form the interconnect layer on the dielectric layer and the second contact window in the dielectric layer.

17. A method of manufacturing a semiconductor structure as claimed in claim 16, wherein after forming the conductive layer and before performing the patterning process, a second barrier material layer is further formed on the conductive layer.

18. A method of manufacturing a semiconductor structure as claimed in claim 12, wherein the first contact window is formed before the second contact window is formed.

19. The method of manufacturing a semiconductor structure as claimed in claim 12, further comprising forming a second barrier layer between the first contact window and the dielectric layer and between the first contact window and the second doped semiconductor layer.

20. A method of manufacturing a semiconductor structure as claimed in claim 19, wherein the light reflectivity of the interconnect layer is greater than the light reflectivity of the first barrier layer and the second barrier layer.

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