Patent ID: 8557654

Claim:
A method of forming a punch-through diode comprising: forming a first semiconductor region of a first conductivity type and having a first peak impurity concentration; forming a second semiconductor region of a second conductivity type adjacent to the first semiconductor region and having a second peak impurity concentration that is less than the first peak impurity concentration, including depositing a semiconductor for the second semiconductor region while doping the second semiconductor region with an impurity having the second conductivity type at a level of the second peak impurity concentration; forming a third semiconductor region of the second conductivity type adjacent to the second semiconductor region and having a third peak impurity concentration that is greater than the second peak impurity concentration, including depositing a semiconductor for the third semiconductor region while doping the third semiconductor region with an impurity having the second conductivity type, the doping the third semiconductor region includes increasing the impurity in the third semiconductor region to a level of the third peak impurity concentration; forming a fourth semiconductor region of the second conductivity type adjacent to the third semiconductor region and having a fourth peak impurity concentration that is approximately the second peak impurity concentration, including depositing a semiconductor for the fourth semiconductor region while doping the fourth semiconductor region with an impurity having the second conductivity type, the doping the fourth semiconductor region includes decreasing the impurity in the fourth semiconductor region to a level of the fourth peak impurity concentration; and forming a fifth semiconductor region of the first conductivity type adjacent to the fourth semiconductor region and having a fifth peak impurity concentration that is approximately the first peak impurity concentration.