Optical coating method, apparatus and product

Abstract

This disclosure is directed to an improved process for making glass articles having optical coating and easy-to clean coating thereon, an apparatus for the process and a product made using the process. In particular, the disclosure is directed to a process in which the application of the optical coating and the easy-to-clean coating can be sequentially applied using a single apparatus. Using the combination of the coating apparatus and the substrate carrier described herein results in a glass article having both optical and easy-to-clean coating that have improved scratch resistance durability and optical performance, and in addition the resulting articles are “shadow free.”

We claim: 
     
         1 . A method for making a glass article having an optical coating and an easy-to-clean (ETC) coating on top of the optical coating, the method comprising:
 providing a coating apparatus having a vacuum chamber for deposition of an optical coating and an ETC coating;   providing a magnetic rotatable dome within said vacuum chamber for magnetically positioning a magnetic substrate carrier for receiving a glass substrate thereon that is to be coated;   providing within said vacuum chamber source materials for the optical coating and source materials for the ETC coating;   loading the glass substrate on the magnetic substrate carrier and magnetically attaching the magnetic substrate carrier having the glass substrate thereon to the magnetic rotatable dome;   evacuating the vacuum chamber;   rotating the magnetic rotatable dome and depositing an optical coating on the glass substrate;   rotating the magnetic rotatable dome and depositing the ETC coating on top of the optical coating following deposition of the optical coating, wherein the optical coating is not exposed to ambient atmosphere prior to the deposition of the ETC coating; and   removing the glass substrate having the optical coating and the ETC coating from the vacuum chamber to obtain a glass substrate having a shadow-free optical coating deposited on the glass substrate and the ETC coating deposited on the optical coating.   
     
     
         2 . The method according to  claim 1 , further comprising curing the ETC coating. 
     
     
         3 . The method according to  claim 2 , wherein the ETC coating is cured in air at room temperature. 
     
     
         4 . The method according to  claim 2 , wherein the ETC coating is cured by heating the ETC coating. 
     
     
         5 . The method according to  claim 1 , wherein the vacuum chamber is evacuated to a pressure of less than or equal to 10 −4  Torr. 
     
     
         6 . The method according to  claim 1  further comprising densifying the optical coating as the optical coating is deposited. 
     
     
         7 . The method according to  claim 1 , wherein the vacuum chamber contains at least one e-beam source for vaporizing the source materials for the optical coating. 
     
     
         8 . The method according to  claim 7 , wherein the at least one e-beam source comprises greater than or equal to 2 and less than or equal to 6 e-beam sources and an e-beam from each source is directed to a separate container holding a material being coated. 
     
     
         9 . The method according to  claim 1 , wherein the magnetic substrate carrier is selected from the group consisting of a fixed magnetic substrate carrier and an adjustable magnetic substrate carrier. 
     
     
         10 . The method according to  claim 1 , wherein depositing the optical coating comprises depositing a multilayer optical coating comprising at least one period of a high refractive index material and a low refractive index material, wherein:
 the high refractive index material is selected from the group consisting of ZrO 2 , HfO 2 , Ta 2 O 5 , Nb 2 O 5 , TiO 2 , Y 2 O 3 , Si 3 N 4 , SrTiO 3 , WO 3 ; and   the low refractive index material is selected from the group consisting of SiO 2 , MgF 2 , YF 3 , YbF 3  and Al 2 O 3 .   
     
     
         11 . The method according to  claim 1 , wherein the glass substrate is formed from ion-exchanged silica glass, non-ion-exchanged silica glass, aluminosilicate glass, borosilicate glass, aluminoborosilicate glass, or soda lime glass. 
     
     
         12 . The method according to  claim 1 , wherein the source material for the ETC coating is a alkyl perfluorocarbon silane of formula (R F ) x SiX 4-x , where R F  is a linear C 6 -C 30  alkyl perfluorocarbon, X═Cl or —OCH 3 — and x=2 or 3. 
     
     
         13 . The method according to  claim 1 , wherein a variation in a thickness of the optical coating across a coated surface of the glass substrate is less than or equal to 3%. 
     
     
         14 . The method according to  claim 1 , wherein a variation in a thickness of the optical coating across a coated surface of the glass substrate is less than or equal to 2%. 
     
     
         15 . The method according to  claim 1 , wherein a variation in a thickness of the optical coating across a coated surface of the glass substrate is less than or equal to 1%. 
     
     
         16 . A magnetic substrate carrier for holding a substrate during a coating process, the magnetic substrate carrier comprising:
 a non-magnetic substrate carrier base;   a plurality of magnets attached to the non-magnetic substrate carrier base;   a plurality of pins for supporting a surface of a glass substrate positioned on the magnetic substrate carrier;   a spring system comprising a retractable pin held in place by a spring that retracts the retractable pin, the retractable pin being extendable in a direction opposite the spring, a plurality of fixed pins, and a plurality of side stoppers extending from the non-magnetic substrate carrier base for a distance such that, when the glass substrate is positioned on the plurality of pins, tops of the plurality of side stoppers are below a top surface of the glass substrate.   
     
     
         17 . A magnetic substrate carrier for holding substrates during a coating process, the magnetic substrate carrier comprising:
 a non-magnetic carrier base;   a plurality of magnets attached to the non-magnetic carrier base;   a plurality of pins for supporting a surface of a glass substrate;   a housing with a retractable pin disposed in the housing, wherein the retractable pin is held in place by a spring, the retractable pin being outwardly biased from the housing;   optional stoppers; and   a plurality of movable pins for holding an edge of a glass substrate.   
     
     
         18 . A glass article comprising an optical coating and an easy-to-clean coating on top of the optical coating, the glass article being shadow free across an optically coated surface of the glass article, wherein:
 the optical coating comprises a plurality of periods consisting of a layer of high refractive index material H having an index of refraction n greater than or equal to 1.7 and less than or equal to 3.0, and a layer of low refractive index material L having an index of refraction n greater than or equal to 1.3 and less than or equal to 1.6, the layer of high refractive index material H being a first layer of each period and the layer of low refractive index material L being a second layer of each period; and   an SiO 2  capping layer having a thickness in a range greater than or equal to 20 nm and less than or equal to 200 nm applied on top of the plurality of periods.   
     
     
         19 . The glass article according to  claim 18 , wherein a number of coating periods is in a range from greater than or equal to 2 and less than or equal to 1000. 
     
     
         20 . The glass article according to  claim 18 , wherein the optical coating has a thickness in a range from greater than or equal to 100 nm to less than or equal to 2000 nm. 
     
     
         21 . The glass article according to  claim 18 , wherein a number of coating periods is in a range from greater than or equal to 2 and less than or equal to 20, and a thickness of each layer of high refractive index material H and low refractive index material L is in a range from greater than or equal to 5 nm and less than or equal to 200 nm. 
     
     
         22 . The glass article according to  claim 18 , wherein the layer of high refractive index material H is selected from the group consisting of ZrO 2 , HfO 2 , Ta 2 O 5 , Nb 2 O 5 , TiO 2 , Y 2 O 3 , Si 3 N 4 , SrTiO 3  and WO 3 . 
     
     
         23 . The glass article according to  claim 18 , wherein the layer of low refractive index material L is selected from the group consisting of SiO 2 , MgF 2 , YF 3 , YbF 3 , and Al 2 O 3 . 
     
     
         24 . The glass article according to  claim 18 , wherein the glass article has a water contact angle of at least 75° after 6,000 abrasion cycles. 
     
     
         25 . The glass article according to  claim 18 , wherein after 8,000 abrasion cycles, scratches on a surface of the glass article are less than 2 mm in length. 
     
     
         26 . The glass article according to  claim 18 , wherein a % Reflectance of the glass article after at least 8,000 abrasion/wiping cycles is substantially the same as the % Reflectance of an unabraded/unwiped glass article. 
     
     
         27 . The glass article according to  claim 18 , wherein a % Transmission of the glass article after at least 8,000 abrasion/wiping cycles is substantially the same as the % Transmission of an unabraded/unwiped glass article. 
     
     
         28 . The glass article according to  claim 18 , wherein a variation in a thickness of the optical coating across a coated surface of the glass article is less than or equal to 3%. 
     
     
         29 . The glass article according to  claim 18 , wherein a variation in a thickness of the optical coating across a coated surface of the article is less than or equal to 2%. 
     
     
         30 . The glass article according to  claim 18 , wherein a variation in a thickness of the optical coating across a coated surface of the glass article is less than or equal to 1%. 
     
     
         31 . A coating apparatus for coating a substrate with an optical coating and an ETC coating, the coating apparatus comprising:
 a vacuum chamber;   a magnetic rotatable dome positioned in the vacuum chamber;   at least one e-beam source positioned in the vacuum chamber;   at least one thermal evaporation source positioned in the vacuum chamber; and   a shadow mask adjustably positioned on a support within the vacuum chamber.   
     
     
         32 . The coating apparatus of  claim 31 , further comprising a plasma source positioned in the vacuum chamber. 
     
     
         33 . The coating apparatus of  claim 31 , wherein the magnetic rotatable dome comprises:
 an opening at a top center of the magnetic rotatable dome;   a transparent glass plate covering the opening of the magnetic rotatable dome; and   a quartz monitor positioned in an opening in the transparent glass plate for monitoring a deposition rate of coating material deposited in the vacuum chamber.   
     
     
         34 . The coating apparatus of  claim 33 , further comprising an optical fiber positioned above the transparent glass plate, wherein the optical fiber collects light reflected from the transparent glass plate as the transparent glass plate is coated to determine a change in reflectance of the transparent glass plate and thereby a thickness of coatings applied to the transparent glass plate. 
     
     
         35 . The coating apparatus of  claim 31 , wherein the magnetic rotatable dome is attached to a vacuum shielded rotation shaft to facilitate rotation of the magnetic rotatable dome. 
     
     
         36 . The coating apparatus of  claim 31 , further comprising at least one magnetic substrate carrier magnetically attached to the magnetic rotatable dome.