Patent ID: 9276209
Filing Date: 2016-03-01
CPC Classification: H01L

Claim Text:
1. A method comprising: forming a plurality of shallow trench isolation (STI) regions extending into a semiconductor substrate; performing a first implantation to implant a portion of the semiconductor substrate between two of the plurality of STI regions to form a first doped semiconductor region of a first conductivity type, wherein implanted ions penetrate through a second doped semiconductor region that is overlying and contacting the first doped semiconductor region, wherein a diode is formed, with the diode comprising the first doped semiconductor region and the second doped semiconductor region forming a p-n junction, and wherein a conductivity type of the second doped semiconductor region remains unchanged by the first implantation, and remains to be of a second conductivity type opposite to the first conductivity type; forming a phase change element over and electrically coupled to the diode; when the diode is formed, simultaneously forming an additional diode in the semiconductor substrate; implanting an additional portion of the semiconductor substrate to form a word-line in the semiconductor substrate and under the first doped semiconductor region, wherein the word-line is of the first conductivity type, and has a higher impurity concentration than the first doped semiconductor region; performing a second implantation to convert the additional diode into a pickup region of the first conductivity type, wherein the pickup region extends from a top surface of the semiconductor substrate to the word-line; and forming a silicide region on the pickup region.