Patent ID: 9305775
Filing Date: 2016-04-05
CPC Classification: H01L

Claim Text:
1. A method of fabricating an access device, the method comprising: forming a silicon layer on a semiconductor substrate; doping the silicon layer with a first-type ion to form a first-type semiconductor layer directly over the semiconductor substrate to a first predetermined height; doping the silicon layer with a first counter ion to form a first counter-doping layer directly over the first-type semiconductor layer to a second predetermined height, wherein the first counter ion has different conductivity from the first-type ion; doping the silicon layer with a second counter ion to form a second counter-doping layer over the first counter-doping layer to a third predetermined height, wherein the second counter-doping layer is separated from the first counter-doping layer, wherein the second counter ion has the same conductivity as the first-type ion; and doping the silicon layer with a second-type ion to form a second-type semiconductor layer directly over the second counter-doping layer, wherein the second-type ion has different conductivity from the first-type ion.