Method for manufacturing a CMOS image sensor having a capacitor's top electrode in contact with a photo-sensing element
View Patent ↗An image sensor includes a plurality of unit pixels for sensing a light beam to generate an image data. Each of the unit pixels includes, a photoelectric element for sensing a light beam incident thereto and generating photoelectric charges, a transistor including a gate dielectric formed adjacent to the photoelectric element and a gate electrode formed on top of the gate dielectric and a capacitor structure including an insulating film formed on a portion of the photoelectric element and a bottom electrode, wherein the insulating film and the gate dielectric are made of a same material and the bottom electrode and the gate electrode are made of a same material.
1. A method for manufacturing an image sensor, the method comprising:
a) forming a photo-sensing element in a semiconductor substrate;
b) forming a first dielectric layer on top of the semiconductor substrate;
c) forming a first conductive layer on top of the first dielectric layer;
d) patterning, substantially simultaneously, the first dielectric layer and the first conductive layer to form an insulating film and a bottom electrode of a capacitor structure and a gate dielectric and a gate electrode of a transfer transistor;
e) forming successively a second dielectric layer and a second conductive layer over the semiconductor substrate; and
f) removing portions of the second conductive layer and the second dielectric layer that overlie the photoelectric element and overlie the gate dielectric to form a capacitor dielectric and a top electrode of the capacitor structure; wherein a portion of the top electrode is in contact with the photo-sensing element.
2. The method of claim 1 , wherein the step c) includes:
c1) pattering the first dielectric layer into a predetermined configuration to form the insulating film and the gate dielectric, substantially simultaneously; and
c2) patterning the first conductive layer into the predetermined configuration to form the bottom electrode and the gate electrode, substantially simultaneously.
3. The method of claim 1 further comprising:
g) implanting dopants of a first type into an exposed portion of the semiconductor substrate that is between the insulating film and the gate dielectric to form the photo-sensing element.
4. The method of claim 3 further comprising implanting dopants of a second type into a portion of the semiconductor substrate adjacent the the gate electrode.
5. The method of claim 1 , wherein the gate dielectric is semiconductor oxide (SiOx).
6. The method of claim 1 , wherein the gate dielectric is tantalum oxide (Ta 2 O 5 ).
7. The method of claim 1 , wherein the insulating film and the gate dielectric are formed of the same type of material.
8. The method of claim 1 , wherein the gate electrode and the bottom electrode are formed of the same type of material.
9. The method of claim 8 , wherein the material is doped polysilicon.
10. A method for manufacturing an image sensor, the method comprising:
forming a photo-sensing element in a semiconductor substrate;
forming a capacitor structure on the semiconductor substrate, wherein forming the capacitor structure includes:
forming an insulating film on a surface of the semiconductor substrate adjacent the photo-sensing element,
forming a bottom electrode on top of the insulating film,
forming a capacitor dielectric layer on top of the bottom electrode; and
forming a top electrode on top of the capacitor dielectric layer and in contact with the photo-sensing element; and
forming a transfer transistor on the semiconductor substrate.
11. The method of claim 10 , wherein forming the transfer transistor includes:
forming a gate oxide layer on the surface of the semiconductor substrate adjacent the photo-sensing element; and
forming a gate electrode on top of the gate oxide layer.
12. The method of claim 11 , wherein forming the gate electrode and forming the insulating film are performed in the same processing steps.
13. The method of claim 11 , wherein forming the gate electrode and forming the bottom electrode are performed in the same processing steps.
14. The method of claim 11 , wherein forming the transfer transistor further includes forming a sensing node adjacent the gate oxide layer.
15. The method of claim 10 , wherein forming the capacitor dielectric layer includes contacting the capacitor dielectric layer to the photo-sensing element.
16. The method of claim 10 further comprising forming a spacer adjacent a side of the insulating film and a side of the bottom electrode.
17. The method of claim 10 further comprising forming a spacer adjacent to a side of the transfer transistor.
18. The method of claim 10 further comprising forming an isolation region in the semiconductor substrate, wherein a portion of the capacitor structure is formed on top of the isolation region.
19. A method for manufacturing an image sensor, the method comprising:
forming a photo-sensing element in a semiconductor substrate;
forming a capacitor structure on the semiconductor substrate, wherein forming the capacitor structure includes:
forming an insulating film on a surface of the semiconductor substrate adjacent the photo-sensing element,
forming a bottom electrode on top of the insulating film,
forming a capacitor dielectric layer on top of the bottom electrode;
forming a top electrode on top of the capacitor dielectric layer; and
forming a conducting member on top of the top electrode and in contact with the photo-sensing element; and
forming a transfer transistor on the semiconductor substrate.
20. The method of claim 19 , wherein forming the transfer transistor includes:
forming a gate oxide layer on another surface of the semiconductor substrate adjacent the photo-sensing element; and
forming a gate electrode on top of the gate oxide layer.
21. The method of claim 20 , wherein forming the gate electrode and forming the insulating film are performed in the same processing steps.
22. The method of claim 20 , wherein forming the gate electrode and forming the bottom electrode are performed in the same processing steps.
23. The method of claim 20 , wherein forming the transfer transistor further includes forming a sensing node adjacent the gate oxide layer.
24. The method of claim 19 , wherein forming the capacitor dielectric layer includes contacting the capacitor dielectric layer to the photo-sensing element.
25. The method of claim 19 further comprising forming a spacer adjacent a side of the insulating film and a side of the bottom electrode.
26. The method of claim 19 further comprising forming a spacer adjacent to a side of the transfer transistor.
27. The method of claim 19 further comprising forming an isolation region in the semiconductor substrate, wherein a portion of the capacitor structure is formed on top of the isolation region.
28. The method of claim 19 , wherein:
a portion of the capacitor dielectric layer is formed over a portion of the photo-sensing element; and
a portion of the top electrode is formed over the portion of the capacitor dielectric layer that is formed over the portion of the photo-sensing element.
29. The method of claim 28 , wherein the portion of the capacitor dielectric layer that is formed over the photo-sensing element is configured to insulate the top electrode from the photo-sensing element.
30. A method for manufacturing an image sensor, the method comprising:
forming a photo-sensing element in a semiconductor substrate;
forming a first dielectric layer on top of the semiconductor substrate;
forming a first conductive layer on top of the first dielectric layer;
patterning, substantially simultaneously, the first dielectric layer and the first conductive layer to form an insulating film and a bottom electrode of a capacitor structure and a gate dielectric and a gate electrode of a transfer transistor;
forming successively a second dielectric layer and a second conductive layer over the semiconductor substrate;
removing portions of the second conductive layer and the second dielectric layer that overlie the photoelectric element and overlie the gate dielectric to form a capacitor dielectric and a top electrode of the capacitor structure; and
forming a conductive member over a portion of the top electrode and a portion of the photo-sensing element; wherein the conductive member electrically couples the top electrode and the photo-sensing element.
31. The method of claim 30 further comprising implanting dopants of a first type into an exposed portion of the semiconductor substrate that is between the insulating film and the gate dielectric to form the photo-sensing element.
32. The method of claim 31 , wherein the dopants are N + dopants.
33. The method of claim 31 further comprising implanting dopants of a second type into a portion of the semiconductor substrate adjacent the gate elcctrode.
34. The method of claim 31 , wherein the first and second types of dopants are the same type of dopant.
35. The method of claim 31 , wherein the first and second types of dopants are N + dopants.
36. The method of claim 30 , wherein the gate dielectric is semiconductor oxide (SiOx).
37. The method of claim 30 , wherein the gate dielectric is tantalum oxide (Ta 2 O 5 ).
38. The method of claim 30 , wherein the insulating film and the gate dielectric are formed of the same type of material.
39. The method of claim 30 , wherein the gate electrode and the bottom electrode are formed of the same type of material.
40. The method of claim 36 , wherein the same type of material is doped polysilicon.