Patterned thin-film deposition using collimating heated mask asembly

Abstract

Scanning localized evaporation and deposition of an evaporant on a substrate utilizes a mask assembly comprised of a series of mask elements with openings thereon and spaced apart in a stack. The openings are aligned so as to direct the evaporant therethrough onto the substrate. The mask elements are heated and the stack may include a movable shutter element to block openings in adjacent mask elements. The evaporant streams are usually vertical but some may be oblique to the substrate, and they may be of different materials.

1 . In a method for vacuum deposition of a thin film of at least one vaporizable material on a substrate using a mask assembly the steps comprising: 
 (a) providing shadow mask elements having identical patterned openings therethrough;    (b) assembling a multiplicity of said mask elements with spaces to produce a stack in which said openings are aligned and said mask elements are spaced apart;    (c) disposing said mask stack closely adjacent to but spaced from a substrate;    (d) heating said mask elements; and    (e) evaporating a material above said assembled masks to produce a stream of evaporant passing through said aligned openings in said mask elements and depositing on said substrate in a controlled pattern.    
     
     
         2 . The thin film vacuum deposition method in accordance with  claim 1  wherein said mask elements are heated to provide a temperature profile in which the mask element at the end of the stack adjacent the substrate is at a lower temperature than the mask element at the other end of the stacked elements.  
     
     
         3 . The thin film vacuum deposition method in accordance with  claim 1  wherein said openings in adjacent mask elements are in spatial alignment to produce an evaporant stream, which is perpendicular to the plane of said substrate.  
     
     
         4 . The thin film vacuum depositions method in accordance with  claim 1 , wherein some of said openings in adjacent mask elements are obliquely aligned to produce an evaporant stream which is at an oblique angle of incidence to the plane of said substrate.  
     
     
         5 . The thin film vacuum deposition method in accordance with  claim 4 , wherein two oblique evaporant streams with different angles of incidence on the substrate are used to obtain unique deposition profiles.  
     
     
         6 . The thin film vacuum deposition method in accordance with  claim 5  wherein said evaporant steams are of different materials.  
     
     
         7 . The thin film vacuum deposition method in accordance with  claim 1 , wherein evaporant streams of different materials are sequentially deposited each with its own thickness profile in spatial relation to the other.  
     
     
         8 . The thin film vacuum deposition method in accordance with  claim 1 , wherein said mask assembly stack includes insertion of a movable shutter element in said stack, and where there is included the step of moving said shutter element to block some of the openings in at least some of said mask elements.  
     
     
         9 . A collimating mask apparatus for depositing an evaporant on a substrate in a predetermined pattern comprising: 
 (a) a multiplicity of substantially planar shadow mask elements having identically patterned openings; and    (b) spacers disposed between said shadow mask elements to separate said masks from each other, and provide a mask assembly; and    (d) said openings in said shadow masks elements being aligned with each other to spatially direct evaporant through said mask assembly onto a substrate.    
     
     
         10 . The collimating mask apparatus of  claim 9  wherein there is included means for heating said shadow mask elements.  
     
     
         11 . The collimating mask apparatus of  claim 9 , wherein said means for heating said shadow mask elements comprises fabrication of said shadow mask elements from an electrically resistive material, and means for applying current thereto to effect heating thereof to a desired temperature.  
     
     
         12 . The collimating mask apparatus of  claim 11 , wherein said means for applying a current thereto provides control of current to the individual mask elements to obtain a desired temperature profile across said mask assembly.  
     
     
         13 . The collimating mask apparatus of  claim 11 , wherein the thickness of the individual shadow mask elements varies across said mask assembly to obtain a desired temperature profile.  
     
     
         14 . The collimating mask apparatus of  claim 9 , wherein the spacing between said individual shadow mask elements increases across said mask assembly to obtain a desired temperature profile.  
     
     
         15 . The collimating mask apparatus of  claim 9 , wherein said spacers separating the individual mask elements are of equal thickness.  
     
     
         16 . The collimating mask apparatus of  claim 9 , wherein said spacers separating the individual mask elements are of unequal thickness.  
     
     
         17 . A collimating mask apparatus of  claim 9 , wherein said patterned openings in said individual mask elements are of different shapes and sizes, said openings being arranged with respect to each other to direct evaporant to a desired location on a substrate.  
     
     
         18 . The collimating mask apparatus of  claim 9 , wherein at least some of said openings in adjacent shadow mask elements are obliquely aligned in at least one axis to spatially direct some of the evaporant at an oblique angle onto a substrate.  
     
     
         19 . The collimating mask apparatus of  claim 9 , wherein said openings in adjacent shadow mask elements are oriented to direct evaporant to a site, in streams directed from at least two oblique angles.  
     
     
         20 . The collimating mask apparatus of  claim 9 , wherein some of said openings in adjacent shadow mask elements are oriented to direct evaporant in a perpendicular stream and other openings are obliquely aligned to direct evaporant in oblique streams to said substrate to produce at least one element of the pattern on the substrate as a composite of perpendicular and oblique streams, respectively.  
     
     
         21 . The collimating mask apparatus of  claim 9 , wherein said mask assembly includes shutter means for covering said openings.  
     
     
         22 . A scanning localized evaporation apparatus comprising: 
 (a) a base for supporting a substrate;    (b) a mask assembly spaced above said base and comprising    (c) an evaporant source spaced above said mask assembly;    (d) means for heating said mask assembly; and    (e) means for heating said evaporant source to evaporate the material into a stream which passes through said aligned openings of said mask assembly to deposit on the substrate.    
     
     
         23 . The scanning localized evaporation apparatus of  claim 22 , where the mask elements are electrically heated.  
     
     
         24 . The scanning localized evaporation apparatus of  claim 22 , wherein the individual mask elements are comprised of electrically resistive materials including and the spacers are of insulators.  
     
     
         25 . The scanning localized evaporation apparatus of  claim 22  wherein the heating between said individual shadow mask elements is controlled across said mask assembly to obtain a desired temperature profile.  
     
     
         26 . The scanning localized evaporation apparatus of  claim 22  wherein there is included an actuator for movement of said shutter.  
     
     
         27 . The scanning localized evaporation apparatus of  claim 22  wherein said mask assembly includes a moveable mask element disposed between additional mask elements, said movable mask element being translatable to block the openings in the adjacent mark element.  
     
     
         28 . The scanning localized evaporation apparatus of  claim 22  wherein said base for supporting said substrate is mounted on a transport mechanism for moving and indexing said substrate.  
     
     
         29 . The scanning localized evaporation apparatus of  claim 22  wherein the said evaporation source and said heated mask assembly are mounted on a second transport mechanism for moving and indexing said evaporation source and said heated mask assembly.  
     
     
         30 . The scanning localized evaporation apparatus of  claim 28  wherein the said evaporation source and said heated mask assembly are mounted on a second transport mechanism for moving and indexing said evaporation source and said heated mask assembly.