US Patent 7442631 Doping method and method of manufacturing field effect transistor

A doping method comprising the steps of; obtaining a proportion X of ions of a compound including a donor or an acceptor impurity in total ions from mass spectrum by using a first source gas of a first concentration; analyzing a peak concentration Y of the compound in a first processing object which is doped by using a second source gas of a second concentration equal to or lower than the first concentration, referring to a dose amount of total ions as D0 and setting an acceleration voltage at a value, obtaining a dose amount D1 of total ions from a expression, Y=(D1/D0)(aX+b), and doping a second processing object with the donor or the acceptor impurity by a ion doping apparatus using a third source gas, wherein a dose amount of total ions is set at D1, and an acceleration voltage is set at the value.