what is proposed is a method of producing at least two differently heavily doped subzones predominantly doped with a first dopant type in a silicon substrate , in particular for a solar cell . the method comprises : covering at least a first subzone of the silicon substrate in which a heavier doping with the first dopant type is to be produced with a doping layer of borosilicate glass , wherein at least a second subzone of the silicon substrate in which a lighter doping with the first dopant type is to be produced is not covered with the doping layer , and wherein boron as a dopant of a second dopant type differing from the first dopant type and oppositely polarized with respect to the same is included in the layer , and ; heating the such prepared silicon substrate to temperatures above 300 ° c ., preferably above 900 ° c ., in a furnace in an atmosphere containing significant quantities of the first dopant type . additionally , at least a third doped subzone doped with the second dopant type may be produced by the method additionally comprising , prior to the heating , a covering of the doping layer , above the third doped subzone to be produced , with a further layer acting as a diffusion barrier for the first dopant type . the method uses the observation that a borosilicate glass layer seems to promote an in - diffusion of phosphorus from a gas atmosphere and may substantially facilitate a manufacturing for example of solar cells , in particular back contact solar cells .