Image sensor including multiple lenses and method of manufacture thereof

Abstract

A device includes an image sensing element. The device also includes a Silicon Dioxide (SiO 2 ) layer, located over the image sensing element, exhibiting a first index of refraction. The device further includes a first lens, located over the SiO 2 layer, exhibiting a second index of refraction greater than the first index of refraction. The device still further includes a color filter located over the first lens and a second lens located over the color filter.

1 . A method for manufacturing an image sensor, the method comprising:  
     forming an image sensing element;  
     forming over the image sensing element, a Silicon Dioxide (SiO 2 ) layer exhibiting a first index of refraction;  
     forming over the SiO 2  layer, a first lens exhibiting a second index of refraction greater than the first index of refraction;  
     forming a color filter over the first lens; and  
     forming a second lens over the color filter.  
   
   
       2 . The method of  claim 1 , wherein the first lens includes Silicon Nitride (SiN).  
   
   
       3 . The method of  claim 1 , wherein the second index of refraction is approximately 2.01.  
   
   
       4 . The method of  claim 1 , wherein the first index of refraction is approximately 1.46.  
   
   
       5 . The method of  claim 1 , wherein the SiO 2  layer is formed by chemical vapor deposition (“CVD”)  
   
   
       6 . The method of  claim 1 , wherein the first lens is formed by CVD.  
   
   
       7 . The method of  claim 1 , wherein the SiO 2  layer is planarized.  
   
   
       8 . The method of  claim 7 , wherein the SiO 2  layer is planarized by chemical-mechanical planarization (“CMP”).  
   
   
       9 . The method of  claim 1 , wherein the SiO 2  layer is wet-etched.  
   
   
       10 . The method of  claim 1 , wherein the color filter includes a resin.  
   
   
       11 . The method of  claim 1 , wherein the color filter includes a polymer.  
   
   
       12 . A device comprising:  
     an image sensing element;  
     a Silicon Dioxide (SiO 2 ) layer, located over the image sensing element, exhibiting a first index of refraction;  
     a first lens, located over the SiO 2  layer, exhibiting a second index of refraction greater than the first index of refraction;  
     a color filter located over the first lens; and  
     a second lens located over the color filter.  
   
   
       13 . The device of  claim 12 , wherein the first lens includes Silicon Nitride (SiN).  
   
   
       14 . The device of  claim 12 , wherein the second index of refraction is approximately 2.01.  
   
   
       15 . The device of  claim 12 , wherein the first index of refraction is approximately 1.46.  
   
   
       16 . The device of  claim 12 , wherein the SiO 2  layer is formed by chemical vapor deposition (“CVD”).  
   
   
       17 . The device of  claim 12 , wherein the first lens is formed by CVD.  
   
   
       18 . The device of  claim 12 , wherein the SiO 2  layer is planarized.  
   
   
       19 . The device of  claim 18 , wherein the SiO 2  layer is planarized by chemical-mechanical planarization (“CMP”).  
   
   
       20 . The device of  claim 12 , wherein the SiO 2  layer is wet-etched.  
   
   
       21 . The device of  claim 12 , wherein the color filter includes a resin.  
   
   
       22 . The device of  claim 12 , and comprising: 
 one or more inter-metal-dielectric (“IMD”) layers.    
   
   
       23 . A device comprising: 
 an image sensing element;    a first convex lens, located over the image sensing element;    a color filter located over the first convex lens; and    a second convex lens located over the color filter.    
   
   
       24 . The device of  claim 1  wherein the first convex lens comprises a curved surface curving toward the image sensing element.  
   
   
       25 . The device of  claim 1  wherein the second convex lens comprises a curved surface curving away from the first convex lens.  
   
   
       26 . The device of  claim 1  wherein the first and second convex lenses each comprises a material selected from the group consisting of silicon nitride and silicon oxynitride.  
   
   
       27 . The device of  claim 1  wherein the first and second convex lenses each comprises an index of refraction greater than that of surrounding materials.