Lens array and method of making same

DETAILED DESCRIPTION FIG.
4 is a flowchart illustrating a method 400 in accordance with an embodiment of the present invention for fabricating a microlens array or a non-spherical lens.
A substrate is first provided in step 402, where the substrate may include an array of CMOS or CCD sensors.
The sensor array may be any suitable size, ranging from small screen applications to large display devices.
A dielectric layer is then deposited on the substrate in step 404.
A patterning layer, such as a spin-on photoresist or other photosensitive material, is deposited on the dielectric layer in step 406.
Selected portions of the patterning layer are removed, such as by conventional photolithography processing, in step 408.
The removed portions expose areas of the dielectric layer where the microlenses or non-spherical lenses are to be formed.
With embodiments having a sensor array, the exposed areas correspond to locations of individual sensor elements.
In step 410, the exposed portions of the dielectric layer are selectively etched, such as with a wet etch, a grey scale mask, or shadow mask, to form controlled curved recesses.
The curved recesses deepest in the center and taper up toward the sides or circumference.
The etching does not remove all the dielectric material such that the underlying substrate or sensors are exposed.
Further, the curved recesses can be any suitable shape, such as semi-spherical or non-spherical, depending on the application.
The remaining portions of the patterning layer are removed in step 412, and the resulting template is ready for further processing steps or can be used for plastic molding of specially designed lenses.
When the template is to be continued for further processing, a layer of inorganic lens material is deposited over dielectric layer, in step 414, to fill in the curved recesses.
The lens material, in one embodiment, has a refractive index higher than that of the dielectric layer.
Examples of suitable lens materials include, but are not limited to, SiO2, SiOxNy, Si3N4, TiO2, a polymer, or plastics in the case of plastic molding