Image sensor production method and image sensor

Abstract

A production method for an image sensor which is provided with a plurality of sensor portions arranged on a semiconductor substrate and each having a first photodiode constituted by a first region of a first conductivity type and a second region of a second conductivity type different from the first conductivity type and a second photodiode constituted by the second region and a third region of the first conductivity type. The method includes the steps of: forming a second region of the second conductivity type on a first region defined in a semiconductor substrate by epitaxial growth; and forming a third region of the first conductivity type on the second region by epitaxial growth.

1 . A production method for an image sensor which comprises a plurality of sensor portions arranged on a semiconductor substrate and each having a first photodiode constituted by a first region of a first conductivity type and a second region of a second conductivity type different from the first conductivity type and a second photodiode constituted by the second region and a third region of the first conductivity type, the method comprising the steps of: 
 forming the second regions of the second conductivity type on the first region defined in the semiconductor substrate by epitaxial growth; and    forming the third regions of the first conductivity type on the second regions by epitaxial growth.    
   
   
       2 . An image sensor production method as set forth in  claim 1 , 
 wherein the second region forming step includes the step of forming a first epitaxial layer of the second conductivity type on an area of the first region including a second region formation area corresponding to the second region,    wherein the third region forming step includes the step of forming a second epitaxial layer of the first conductivity type on an area of the first epitaxial layer including a third region formation area corresponding to the third region,    the image sensor production method further comprising the step of introducing an impurity of the first conductivity type in a predetermined region extending from the first epitaxial layer to the second epitaxial layer to form a well layer of the first conductivity type having a higher impurity concentration than the third region, whereby the first epitaxial layer is divided into the plurality of the second regions by the well layer and the second epitaxial layer is divided into the plurality of the third regions by the well layer.    
   
   
       3 . An image sensor production method as set forth in  claim 2 , further comprising the step of selectively oxidizing a surface of the well layer and its periphery for formation of an isolation region after the well layer forming step.  
   
   
       4 . An image sensor production method as set forth in  claim 1 , further comprising the step of introducing an impurity of the first conductivity type into a surface portion of the third region to form a fourth region of the first conductivity type which has a higher impurity concentration than the other portion of the third region.  
   
   
       5 . An image sensor production method as set forth in  claim 1 , further comprising the step of forming a functional device in the semiconductor substrate.  
   
   
       6 . An image sensor production method as set forth in  claim 1 , further comprising the step of forming a CMOS in the semiconductor substrate.  
   
   
       7 - 13 . (canceled)