Passivation planarization
View Patent ↗A pixel cell is formed by locating a first passivation layer over the final layer of metal lines. Subsequently, the uneven, non-uniform passivation layer is subjected to a planarization process such as chemical mechanical polishing, mechanical abrasion, or etching. A spin-on-glass layer may be deposited over the non-uniform passivation layer prior to planarization. Once a uniform, flat first passivation layer is achieved over the final metal, a second passivation layer, a color filter array, or a lens forming layer with uniform thickness is formed over the first passivation layer. The passivation layers can be oxide, nitride, a combination of oxide and nitride, or other suitable materials. The color filter array layer may also undergo a planarization process prior to formation of the lens forming layer. The present invention is also applicable to other devices.
1. A method of forming a semiconductor device, said method comprising:
providing a passivation layer located over a final metallization layer,
wherein said passivation layer includes an oxide passivation layer;
planarizing a surface of said passivation layer;
stopping said planarizing before reaching said final metallization layer;
forming a second layer over said passivation layer;
providing a color filter array layer over said second layer;
planarizing a surface of said color filter array layer; and
providing a lens layer over said color filter array layer.
2. The method of claim 1 , wherein said second layer includes a nitride passivation layer.
3. The method of claim 1 , wherein said planarizing step includes chemical mechanical polishing.
4. The method of claim 1 , wherein said planarizing step includes mechanical abrasion.
5. The method of claim 1 , wherein said planarizing step includes etching.
6. The method of claim 5 , wherein said etching is anisotropic.
7. The method of claim 5 , wherein said etching includes a plasma etching step.
8. The method of claim 5 , wherein said etching includes ion beam milling.
9. The method of claim 5 , wherein said etching includes reactive ion etching.
10. The method of claim 1 , wherein said semiconductor device is a CMOS imager.
11. The method of claim 1 , wherein said semiconductor device is a CCD imager.
12. The method of claim 1 , wherein said passivation layer includes a spin-on-glass layer.
13. A method of forming a pixel cell of an imaging device, said method comprising:
forming a passivation layer over a final metallization layer;
planarizing a surface of said passivation layer;
stopping said planarizing before reaching said final metallization layer;
forming a color filter array layer over said passivation layer;
planarizing a top surface of said color filter array layer; and
forming a lens forming layer over said color filter array layer.
14. The method of claim 13 , wherein said top surface of said color filter array layer is planarized by chemical mechanical polishing.
15. The method of claim 13 , wherein said top surface of said color filter array layer is planarized by mechanical abrasion.
16. The method of claim 13 , wherein said top surface of said color filter array layer is planarized by etching.
17. The method of claim 13 , wherein said top surface of said color filter array layer is planarized by forming a planarizing coating thereon.
18. The method of claim 13 , wherein said imaging device is a CMOS imager.
19. The method of claim 13 , wherein said imaging device is a CCD imager.
20. A method of forming a pixel cell of an imaging device, said method comprising:
forming an oxide passivation layer over a top horizontal metal layer comprising a plurality of metal lines, said plurality of metal lines being a final metallization layer;
chemical mechanical polishing a top surface of said oxide passivation layer;
forming a nitride passivation layer over said oxide passivation layer;
forming a color filter array layer over said nitride passivation layer;
planarizing a surface of said color filter array layer; and
providing a lens layer over said color filter array layer.
21. A method of forming a pixel cell of an imaging device, said method comprising:
locating a nitride passivation layer over a top horizontal metal layer comprising metal lines, said metal lines being a final metallization layer;
chemical mechanical polishing a top surface of said nitride passivation layer;
forming a planarized color filter array layer over said nitride passivation layer; and
providing a lens layer over said color filter array layer.