Equipment and process for creating a custom sloped etch in a substrate

Abstract

Equipment and processes for creating a custom sloped etch in a substrate are disclosed. An illustrative process may include the steps of providing a substrate having a surface to be etched, providing a control layer on the surface of the substrate, forming a mask above the control layer, and then selectively etching each of the control layer and substrate at variable rates to form a sloped etch in the substrate.

1 . A method for creating a custom sloped etch in a substrate, comprising the steps of: 
 providing a substrate having a surface;    providing a control layer above the surface of the substrate,    providing a photomask above the control layer, said photomask defining at least one opening exposing at least a portion of the control layer; and    selectively etching the control layer and substrate surface to form a sloped etch within the substrate surface.    
   
   
       2 . The method of  claim 1 , wherein said step of selectively etching the control layer and substrate surface comprises the steps of: 
 applying a first etchant configured to selectively etch the control layer; and    applying a second etchant configured to selectively etch the substrate.    
   
   
       3 . The method of  claim 2 , wherein the etch rate of the first etchant is greater than the etch rate of the second etchant.  
   
   
       4 . The method of  claim 2 , further comprising the step of adjusting the relative concentrations of the first and second etchants during said step of selectively etching the control layer and substrate surface.  
   
   
       5 . The method of  claim 2 , wherein said first etchant is a fast-rate etchant solution of nitric acid.  
   
   
       6 . The method of  claim 2 , wherein said second etchant is a slow-rate etchant solution of hydrofluoric acid.  
   
   
       7 . The method of  claim 1 , wherein said step of selectively etching the control layer and substrate surface comprises the steps of: 
 placing the substrate within an etch bath containing at least one etchant solution; and    heating the substrate at one or more intervals to selectively adjust the relative etch rates of the substrate and the control layer.    
   
   
       8 . The method of  claim 1 , wherein said substrate includes quartz.  
   
   
       9 . The method of  claim 1 , wherein said control layer includes nickel.  
   
   
       10 . The method of  claim 1 , wherein said step of forming a photomask above the control layer comprises the steps of: 
 providing a first photomask layer above the substrate; and    providing a second photomask layer on the first photomask layer.    
   
   
       11 . The method of  claim 10 , wherein said first photomask layer includes a compressive layer of silicon nitride.  
   
   
       12 . The method of  claim 10 , wherein said second photomask layer includes a tensile layer of polysilicon.  
   
   
       13 . The method of  claim 1 , wherein said photomask is a bimorph photomask.  
   
   
       14 . The method of  claim 1 , wherein said at least one opening comprises a longitudinal slit.  
   
   
       15 . The method of  claim 1 , wherein said at least one opening comprises a rectangular slot.  
   
   
       16 . The method of  claim 1 , wherein said at least one opening comprises a plurality of openings.  
   
   
       17 . The method of  claim 1 , wherein said sloped etch is an S-shaped sloped etch.  
   
   
       18 . The method of  claim 1 , wherein said sloped etch has a depth of between about 4 to 8 μm.  
   
   
       19 . The method of  claim 1 , further comprising the step of removing the control layer and photomask after said step of selectively etching the control layer and substrate surface.  
   
   
       20 . A method for creating a custom sloped etch in a substrate, comprising the steps of: 
 providing a substrate having a surface;    providing a control layer above the surface of the substrate,    providing a photomask above the control layer, said photomask defining at least one opening exposing at least a portion of the control layer;    applying a first etchant configured to selectively etch the control layer;    applying a second etchant configured to selectively etch the substrate; and    adjusting the relative concentrations of the first and second etchants to form a sloped etch within the substrate surface.    
   
   
       21 . The method of  claim 20 , wherein the etch rate of the first etchant is greater than the etch rate of the second etchant.  
   
   
       22 . The method of  claim 20 , wherein said first etchant is a fast-rate etchant solution of nitric acid.  
   
   
       23 . The method of  claim 20 , wherein said second etchant is a slow-rate etchant solution of hydrofluoric acid.  
   
   
       24 . The method of  claim 20 , wherein said substrate includes quartz.  
   
   
       25 . The method of  claim 20 , wherein said control layer includes nickel.  
   
   
       26 . The method of  claim 20 , wherein said step of applying a photomask above the control layer comprises the steps of: 
 providing a first photomask layer above the substrate; and    providing a second photomask layer on the first photomask layer.    
   
   
       27 . The method of  claim 26 , wherein said first photomask layer includes a compressive layer of silicon nitride.  
   
   
       28 . The method of  claim 26 , wherein said second photomask layer includes a tensile layer of polysilicon.  
   
   
       29 . The method of  claim 20 , wherein said photomask is a bimorph photomask.  
   
   
       30 . The method of  claim 20 , wherein said at least one opening comprises a longitudinal slit.  
   
   
       31 . The method of  claim 20 , wherein said at least one opening comprises a rectangular slot.  
   
   
       32 . The method of  claim 20 , wherein said at least one opening comprises a plurality of openings.  
   
   
       33 . The method of  claim 20 , wherein said sloped etch is an S-shaped sloped etch.  
   
   
       34 . The method of  claim 20 , wherein said sloped etch has a depth of between about 4 to 8 μm.  
   
   
       35 . The method of  claim 20 , further comprising the step of removing the control layer and photomask after said step of selectively etching the control layer and substrate surface.  
   
   
       36 . A method for creating a custom sloped etch in a substrate, comprising the steps of: 
 providing a substrate having a surface;    providing a nickel control layer above the surface of the substrate,    providing a photomask above the control layer, said photomask defining at least one opening exposing at least a portion of the control layer;    applying a fast-rate etchant solution of nitric acid configured to selectively etch the control layer;    applying a slow-rate etchant solution of hydrofluoric acid configured to selectively etch the substrate; and    adjusting the relative concentrations of the first and second etchant solutions to form a sloped etch in the substrate surface.    
   
   
       37 . A method for creating a custom sloped etch in a substrate, comprising the steps of: 
 providing a substrate having a surface;    providing a control layer above the surface of the substrate,    providing a bimorph photomask above the control layer, said photomask defining at least one opening exposing at least a portion of the control layer; and    selectively etching the control layer and substrate surface to form a sloped etch in the substrate surface.    
   
   
       38 . A system for etching a custom sloped etch in a substrate, the system comprising: 
 a substrate having a sacrificial control layer and at least one mask layer, said at least one mask layer defining one or more openings exposing the control layer; and    etching means for selectively etching the substrate and control layer to form a sloped etch in the substrate.    
   
   
       39 . The system of  claim 38 , wherein said etching means includes a first etchant source configured to adjustably etch the control layer at a first etch rate, and a second etchant source configured to adjustably etch the substrate at a second etch rate.  
   
   
       41 . The system of claim  40 , wherein said first etch rate is greater than said second etch rate.  
   
   
       42 . The system of  claim 39 , wherein said etching means includes an etch bath and at least one heater element.  
   
   
       43 . The system of  claim 42 , further comprising a controller adapted to regulate the temperature of said at least one heater element.  
   
   
       44 . The system of  claim 42 , further comprising a temperature sensor operatively coupled to said controller, said temperature sensor being adapted to monitor the temperature within said etch bath.  
   
   
       45 . A system for etching a custom sloped etch in a substrate, the system comprising: 
 a substrate having a sacrificial control layer and at least one mask layer, said at least one mask layer defining one or more openings exposing the control layer; and    an etching apparatus configured to deliver at least one etchant solution into an etch bath containing the substrate, said at least one etchant solution being configured to selectively etch the substrate and control layer at an adjustable rate to form a sloped etch in the substrate.    
   
   
       46 . A system for etching a custom sloped etch in a substrate, the system comprising: 
 a substrate having a sacrificial control layer and at least one mask layer, said at least one mask layer defining one or more openings exposing the control layer; and    an etching apparatus configured to deliver a first etchant solution configured to adjustably etch the control layer at a first etch rate, and a second etchant solution configured to adjustably etch the substrate at a second etch rate different than said first etch rate.