Surface emitting semiconductor laser

Abstract

A method of forming a conductive pattern such as an electrode on a compound semiconductor layer includes the steps of forming a first organic layer on the compound semiconductor layer, forming a second layer on the first organic layer, the second layer being resistant to plasma ashing, forming a pattern including a first aperture in the second layer, forming a second aperture in the first organic layer by the plasma ashing of the first organic layer using a mask of the pattern including the first aperture to expose the compound semiconductor layer in the second aperture, depositing a conductive layer over a region including the compound semiconductor layer exposed in the second aperture and the second layer, and forming the conductive pattern on the compound semiconductor layer by a lift-off process.

1 . A method of forming a conductive pattern such as an electrode on a compound semiconductor layer comprising the steps of: 
 forming a first organic layer on the compound semiconductor layer;    forming a second layer on the first organic layer, the second layer being resistant to plasma ashing;    forming a pattern including a first aperture in the second layer;    forming a second aperture in the first organic layer by plasma ashing of the first organic layer using a mask pattern including the first aperture to expose the compound semiconductor layer in the second aperture; and    depositing a conductive layer over a region including the compound semiconductor layer exposed in the second aperture and the second layer;    wherein forming the pattern in the second layer includes forming the conductive pattern by a lift-off process.    
     
     
         2 . The method as claimed in  claim 1 , wherein the plasma ashing comprises an oxygen radical.  
     
     
         3 . The method as claimed in  1 , wherein the first organic layer comprises a photoresist layer.  
     
     
         4 . The method as claimed in  claim 3 , wherein the method further comprises a step of baking the first organic layer at a predetermined temperature.  
     
     
         5 . The method as claimed in  claim 1 , wherein the second layer comprises a photoresist having silicon which is resistant to the oxygen radical.  
     
     
         6 . The method as claimed in  claim 1 , wherein the second layer comprises an inorganic film.  
     
     
         7 . The method as claimed in  claim 1 , wherein the second aperture of the first organic layer is processed by the plasma ashing to form an undercut to the first aperture of the second layer.  
     
     
         8 . The method as claimed in  claim 1 , wherein the compound semiconductor layer comprises a compound semiconductor substrate.  
     
     
         9 . The method as claimed in  claim 1 , wherein the compound semiconductor layer comprises gallium arsenide (GaAs).  
     
     
         10 . A method of forming a conductive pattern over a compound semiconductor layer, the method comprising the steps of: 
 forming a first organic layer on the compound semiconductor layer;    forming an inorganic layer on the first organic layer;    forming a second organic layer on the inorganic layer;    forming a first pattern including a first aperture in the second organic layer;    forming a second pattern including a second aperture in the inorganic layer by etching the inorganic layer using a mask of the first pattern including the first aperture;    forming a third aperture in the first organic layer by plasma ashing of the first organic layer using a mask of the second pattern including the second aperture to expose the compound semiconductor layer in the third aperture;    depositing a conductive film over a region including the compound semiconductor layer exposed in the third aperture and the second organic layer; and    forming the conductive pattern on the compound semiconductor layer by a lift-off process.    
     
     
         11 . The method as claimed in  claim 10 , wherein the first and second organic layers comprise photoresists respectively.  
     
     
         12 . The method as claimed in  claim 10 , wherein the inorganic layer comprises indium-tin-oxide (ITO) or silicon oxide (SiO).  
     
     
         13 . The method as claimed in  claim 10 , wherein the plasma ashing comprises an oxygen radical.  
     
     
         14 . The method as claimed in  claim 10 , wherein the third aperture of the first organic layer is formed in a shape of an undercut to the second aperture of the inorganic layer.  
     
     
         15 . A method of manufacturing a surface emitting semiconductor laser, the surface emitting semiconductor laser including a first semiconductor mirror layer of first conductivity type over a substrate, a current confining layer over the first semiconductor mirror layer, an active region over the first semiconductor mirror layer, a second semiconductor mirror layer of second conductivity type over the active region and a contact layer including a compound semiconductor layer over the second semiconductor mirror layer, the method comprising the steps of: 
 forming a first organic layer on the contact layer;    forming a second layer on the first organic layer, the second layer being resistant to a plasma ashing;    forming a pattern including a first aperture in the second layer;    forming a second aperture in the first organic layer by the plasma ashing of the first organic layer using a mask of the pattern including the first aperture to expose the contact layer in the second aperture;    depositing a conductive layer over a region including the contact layer exposed in the second aperture and the second layer; and    forming a conductive pattern on the contact layer by a lift-off process.    
     
     
         16 . The method as claimed in  claim 15 , wherein a mesa structure which is extended from at least the contact layer to the current confining layer is formed, and wherein a part of region of the current confining layer is selectively oxidized from a sidewall of the mesa structure.  
     
     
         17 . The method as claimed in  claim 15 , wherein the conductive pattern is an electrode which is connected with the contact layer in ohmic.  
     
     
         18 . The method as claimed in  claim 15 , wherein the conductive pattern is formed in a ring shape and wherein an inner diameter defines an emission window for the laser light.