Detecting pinholes in vertical cavity surface-emitting laser passivation

Abstract

A method for detecting a passivation pinhole includes forming an oxide vertical cavity surface-emitting laser (VCSEL) having an oxidation cavity, forming a passivation layer over a surface of the oxidation cavity, exposing the oxide VCSEL to an etchant vapor, and inspecting the oxide VCSEL for a defect caused by the etchant vapor.

1 . A method for detecting a passivation pinhole, comprising: 
 forming an oxide vertical cavity surface-emitting laser (VCSEL) having an oxidation cavity;    forming a passivation layer over a surface of the oxidation cavity;    exposing the oxide VCSEL to an etchant; and    inspecting the oxide VCSEL for a defect caused by the etchant.    
     
     
         2 . The method of  claim 1 , wherein said inspecting the oxide VCSEL comprises examining the oxide VCSEL under an infrared light.  
     
     
         3 . The method of  claim 2 , wherein said inspecting the oxide VCSEL further comprises examining the oxide VCSEL with an infrared filter.  
     
     
         4 . The method of  claim 1 , wherein the defect appears under infrared light as an oxidation front caused by the etchant.  
     
     
         5 . The method of  claim 1 , wherein the etchant is in a vapor form.  
     
     
         6 . The method of  claim 5 , wherein the oxide VCSEL is exposed to the etchant inside a furnace.  
     
     
         7 . The method of  claim 1 , wherein the etchant comprises a hydrochloric acid (HCl) vapor.  
     
     
         8 . The method of  claim 7 , further comprising heating a wet HCl to generate the HCl vapor.  
     
     
         9 . The method of  claim 8 , wherein the wet HCl is heated to 30° C.  
     
     
         10 . The method of  claim 9 , wherein the HCl vapor is pressurized by an inert gas supplied at one standard liter per minute.  
     
     
         11 . The method of  claim 10 , wherein the oxide VCSEL is exposed to the HCl vapor inside a furnace at 285° C.  
     
     
         12 . The method of  claim 11 , wherein the oxide VCSEL is exposed to the HCl vapor for two hours.  
     
     
         13 . A system for detecting passivation pinholes, comprising: 
 an etchant supply; and    a chamber, the chamber holding an oxide vertical cavity surface-emitting laser (VCSEL), the chamber receiving an etchant from the etchant supply, the chamber exposing the oxide VCSEL to the etchant.    
     
     
         14 . The system of  claim 13 , wherein the etchant supply comprises a hydrochloric acid bubbler heated by a hotplate and pressurized by a supply of an inert gas.  
     
     
         15 . The system of  claim 13 , wherein the chamber is a horizontal tube furnace.