Image sensor having integrated infrared-filtering optical device and related method

Abstract

An image sensing device is disclosed having a die formed with an array of photosensing sites and a structure of optical material having infrared absorbing characteristics formed over the photosensing sites. An embodiment is disclosed in which the structure of optical material having infrared absorbing characteristics is formed as an array of microlenses for directing visible image light onto the photosensing sites and at the same time filtering out infrared wavelengths that interfere with image capture. Alternatively, the structure may be designed to filter out other ranges of wavelengths outside of the visible spectrum.

1 . A method of fabricating an image sensing device, comprising:
 forming on a substrate imaging sensing electrical elements;   forming a mixture of a wavelength-selective absorption dye and an optically transmissive material; and   processing the mixture into the shapes of microlenses on the substrate over the imaging-sensing electrical elements.   
     
     
         2 . The method of  claim 1 , wherein processing the mixture comprises mixing the dye into the optically transmissive material to form a liquid material and molding the liquid material into the shape of microlenses. 
     
     
         3 . The method of  claim 1 , wherein the dye is selected to absorb infrared wavelengths. 
     
     
         4 . The method of  claim 1 , wherein the dye is selected to absorb wavelengths outside the visible spectrum. 
     
     
         5 . The method of  claim 1 , wherein
 processing the mixture into the shapes of microlenses includes shaping the microlenses into hemispherical shaped lens elements, and   disposing the microlenses as a single layer directly on and in contact with the substrate.   
     
     
         6 . The method of  claim 1 , wherein
 processing the mixture into the shapes of microlenses includes shaping the microlenses into cylindrical shaped lens elements, and   disposing the microlenses as a single layer directly on and in contact with the substrate.   
     
     
         7 . A method of making an imaging device, comprising:
 preparing a substrate having photosensing elements; and   forming a light transmissive infrared absorbing optical layer on the substrate to transmit visible light onto the photosensing elements.   
     
     
         8 . The method of  claim 7 , wherein forming the light-transmissive infrared-absorbing optical layer comprises mixing a dye into a plastic resin and molding the mixed dye and resin while in a liquid state to form the light transmissive infrared absorbing optical layer on the substrate. 
     
     
         9 . The method of  claim 7 , wherein
 forming the optical layer includes forming microlenses, each having a hemispherical shaped lens element, and   disposing the microlenses as a single layer directly on and in contact with the substrate.   
     
     
         10 . The method of  claim 7 , wherein
 forming the optical layer includes forming microlenses, each having a cylindrical shaped lens element, and   disposing the microlenses as a single layer directly on and in contact with the substrate.