Conformal coatings for micro-optical elements

Abstract

A micro-optical element is produced through vapor deposition techniques, such as atomic layer deposition. An optical structure having a surface with uneven structures is exposed to one or more precursor vapors to create a self-limiting film growth on the surface of the optical structure. The film thickness may be increased and controlled by subsequent exposures. The resulting film conforms to surface structures having varying complex dimensions.

1 . A method for fabricating a micro-optical element, comprising: 
 providing an optical structure, the optical structure comprising a trench having vertical and horizontal dimensions less than the wavelength of the entire range of infrared light;    placing the optical structure into a reaction space;    forming a self-limiting film of uniform thickness comprising first and second film layers, the self-limiting film conforming to the trench of the optical structure, and defining a filmed trench, wherein forming the self-limiting film includes, 
 introducing a first chemical into the reaction space such that a portion of the first chemical adsorbs onto the trench of the optical structure and forms a first film layer,  
 after introducing the first chemical, purging the reaction space,  
 introducing a second chemical into the reaction space such that a portion of the second chemical reacts with the adsorbed first chemical to form a second film layer, and  
 after introducing the second chemical, purging the reaction space.  
   
     
     
         2 . The method of  claim 1  wherein the optical structure is a diffractive optical structure.  
     
     
         3 . The method of  claim 1  wherein the optical structure is a refractive optical structure.  
     
     
         4 . The method of  claim 1  wherein the optical structure is selected from the group consisting of a beam shaper, beam splitter, microlens, microlens array, diffuser, laser diode corrector, pattern generator, collimator, grating device, DNA chip, biochip, optical filter, waveguide, optical attenuator, gain flattening filter, gray shade filter, image sensor and anti-reflective coating structures.  
     
     
         5 . The method of  claim 1  wherein the optical structure is disposed on a light detecting device.  
     
     
         6 . The method of  claim 5  wherein the light detecting device is selected from the group consisting of: 
 light diode, solar cell, CCD device, CMOS device and an integrated circuit.    
     
     
         7 . The method of  claim 1  wherein the self-limiting film is selected from the group consisting of: 
 antireflection coating, optical low pass filter, optical high pass filter, optical bandpass filter, optical bandreject filter, waveguide, optical attenuator, gain flattening filter, gray scale filter or a passivation layer.    
     
     
         8 . The method of  claim 1  wherein the optical structure includes a material selected from the group consisting of acrylic, epoxy, fuoro polymer, polyamide, polyimide, polystyrene, polyethylene, polyethylene terephthalate, polyurethane, PTFE, polyolefins, polycarbonate, polymethyl methacrylate (PMMA), EPON SU-8 epoxy resin, organically modified silicates (Ormosils), nanomers, plastics, and plexi-glass.  
     
     
         9 . The method of  claim 1  wherein the self-limiting film includes a material selected from the group of TiO 2 , Al 2 O 3 , HfO 2 , ZnO, SiO 2 , Ta 2 O 5 , and Nb 2 O 5 .  
     
     
         10 . The method of  claim 1  wherein the self-limiting film includes a layered structure of TiO 2  and Al 2 O 3 .  
     
     
         11 . The method of  claim 1  wherein the trench has an aspect ratio of approximately 1 to 10.  
     
     
         12 . The method of  claim 1  wherein introducing the first and second chemicals into the reaction space includes using an inert carrier gas selected from the group consisting of nitrogen, helium, neon, argon, and carbon dioxide.  
     
     
         13 . The method of  claim 1  further comprising flowing an inert gas through the reaction space.  
     
     
         14 . A method for fabricating a micro-optical element, comprising: 
 providing an optical structure, the optical structure comprising an optic including a trench having vertical and horizontal dimensions less than the wavelength of the entire range of infrared light;    placing the optical structure into a reaction space;    forming a self-limiting film of uniform thickness comprising first and second film layers, the self-limiting film conforming to the trench of the optic, and defining a filmed trench, wherein forming the self-limiting film includes, 
 introducing a first chemical into the reaction space such that a portion of the first chemical adsorbs onto the trench of the optic and forms a first film layer,  
 after introducing the first chemical, purging the reaction space,  
 introducing a second chemical into the reaction space such that a portion of the second chemical reacts with the adsorbed first chemical to form a second film layer, and  
 after introducing the second chemical, purging the reaction space.  
   
     
     
         15 . The method of  claim 14  wherein the optical structure is a diffractive optical structure.  
     
     
         16 . The method of  claim 14  wherein the optical structure is a refractive optical structure.  
     
     
         17 . The method of  claim 14  wherein the optical structure is selected from the group consisting of a beam shaper, beam splitter, microlens, microlens array, diffuser, laser diode corrector, pattern generator, collimator, grating device, DNA chip, biochip, optical filter, waveguide, optical attenuator, gain flattening filter, gray shade filter, image sensor and anti-reflective coating structures.  
     
     
         18 . The method of  claim 14  wherein the optical structure is disposed on a light detecting device.  
     
     
         19 . The method of  claim 18  wherein the light detecting device is selected from the group consisting of: 
 light diode, solar cell, CCD device, CMOS device and an integrated circuit.    
     
     
         20 . The method of  claim 14  wherein the self-limiting film is selected from the group consisting of: 
 antireflection coating, optical low pass filter, optical high pass filter, optical bandpass filter, optical bandreject filter, waveguide, optical attenuator, gain flattening filter, gray scale filter or a passivation layer.    
     
     
         21 . The method of  claim 14  wherein the optical structure includes a material selected from the group consisting of acrylic, epoxy, fuoro polymer, polyamide, polyimide, polystyrene, polyethylene, polyethylene terephthalate, polyurethane, PTFE, polyolefins, polycarbonate, polymethyl methacrylate (PMMA), EPON SU-8 epoxy resin, organically modified silicates (Ormosils), nanomers, plastics, and plexi-glass.  
     
     
         22 . The method of  claim 14  wherein the self-limiting film includes a material selected from the group of TiO 2 , Al 2 O 3 , HfO 2 , ZnO, SiO 2 , Ta 2 O 5 , and Nb 2 O 5 .  
     
     
         23 . The method of  claim 14  wherein the self-limiting film includes a layered structure of TiO 2  and Al 2 O 3 .  
     
     
         24 . The method of  claim 14  wherein the trench has an aspect ratio of approximately 1 to 10.  
     
     
         25 . The method of  claim 14  wherein introducing the first and second chemicals into the reaction space includes using an inert carrier gas selected from the group consisting of nitrogen, helium, neon, argon, and carbon dioxide.