Light receiving array, method of manufacturing the array, and optical encoder using the array

Abstract

The present invention has an object to provide a photoreceptor array with an excellent device property and no short fault between adjacent photoreceptors and to provide a method of manufacturing such the photoreceptor array with a high yield. On a transparent substrate ( 31 ), a transparent electrode ( 32 ) and a p-type amorphous silicon layer ( 33 ) are formed. An insulating layer ( 41 ) is deposited thereon to form a trench ( 42 ). In the trench ( 42 ), an i-type amorphous silicon layer ( 34 ), an n-type amorphous silicon layer ( 35 ) and an n-side electrode ( 36 ) are buried in turn to form the photoreceptor array.

What is claimed is:  
     
         1 . A photoreceptor array, comprising: 
 a substrate;    an insulating layer formed on said substrate, said insulating layer having a plurality of trenches formed therein for burying devices;    a plurality of photoreceptors formed from semiconductor layers buried in each of said trenches in said insulating layer; and    an output signal line formed on said plurality of photoreceptors via an interlayer insulator.    
     
     
         2 . The photoreceptor array according to    claim 1    wherein said substrate is composed of a transparent substrate, said array further comprising a transparent electrode formed between said transparent substrate and said insulating layer and operative as a lower electrode common to said plurality of photoreceptors, and wherein the back surface of said substrate is employed to receive a light.  
     
     
         3 . The photoreceptor array according to    claim 1   , wherein said plurality of photoreceptors has upper electrodes, each of which is composed of a transparent electrode, and wherein said upper electrodes are employed to receive a light from above.  
     
     
         4 . The photoreceptor array according to    claim 3   , wherein said plurality of photoreceptors has upper electrodes, each of which is self-aligned with and buried in said trench.  
     
     
         5 . The photoreceptor array according to    claim 1   , wherein said plurality of photoreceptors comprises a plurality of photodiodes.  
     
     
         6 . The photoreceptor array according to    claim 5   , wherein said plurality of photodiodes has a p-type layer and an n-type layer, said p-type layer formed continuously on a lower electrode formed continuously over said substrate, and said n-type layer buried and formed in each trench.  
     
     
         7 . An optical encoder, comprising: 
 a scale having optical gratings formed thereon along a measurement axis; and    a sensor head including a photoreceptor array for detecting displacements of said scale to provide a plurality of displacement signals with different phases, said photoreceptor array including 
 a substrate;  
 a lower electrode formed on said substrate;  
 an insulating layer formed on said substrate, said insulating layer having a plurality of trenches formed therein for burying devices;  
 a plurality of photoreceptors formed from semiconductor layers buried in each of said trenches in said insulating layer, said plurality of photoreceptors each having an upper electrode formed thereon; and  
 an output signal line formed on said plurality of photoreceptors via an interlayer insulator.  
   
     
     
         8 . The optical encoder according to    claim 7   , wherein said substrate is composed of a transparent substrate and said lower electrode is composed of a transparent electrode, and wherein the back surface of said substrate is employed in said photoreceptor array to receive a light therethrough.  
     
     
         9 . The optical encoder according to    claim 7   , wherein said upper electrode is composed of a transparent electrode, and wherein said upper electrode is employed in said photoreceptor array to receive a light therethrough.  
     
     
         10 . A method of manufacturing a photoreceptor array, comprising the steps of: 
 providing a substrate;    forming an insulating layer on said substrate;    forming a plurality of trenches in said insulating layer;    forming a plurality of photoreceptors from semiconductor layers buried in each of said trenches in said insulating layer; and    forming an output signal line on said plurality of photoreceptors via an interlayer insulator.    
     
     
         11 . The method according to    claim 10   , further comprising the step of forming a lower electrode common to said plurality of photoreceptors prior to forming said insulating layer on said substrate.  
     
     
         12 . The method according to    claim 10   , further comprising the steps of: 
 forming a lower electrode common to said plurality of photoreceptors; and    forming a p-type semiconductor layer operative as an anode layer common to said plurality of photoreceptors on said lower electrode prior to forming said insulating layer on said substrate.    
     
     
         13 . The method according to    claim 12   , wherein said step of forming the plurality of photoreceptors includes burying an i-type semiconductor layer and an n-type semiconductor layer in turn in said trenches.  
     
     
         14 . The method according to    claim 12   , wherein said step of forming the plurality of photoreceptors includes burying an i-type semiconductor layer, an n-type semiconductor layer and an upper electrode in turn in said trenches.