NOVELTY - The method for partially etching back a semiconductor layer of a silicon substrate (3), comprises partially arranging the substrate in an etching solution (5), where areas of the semiconductor layer located outside the etching solution are partially removed by means of reactive vapors (11) originating from the etching solution, only up to a remaining residual thickness of the semiconductor layer. A doped semiconductor layer (1) and a silicon layer are etched back. The doped silicon layer is formed through applying dopant in the silicon substrate.    USE - Method for partially etching back a semiconductor layer of a silicon substrate useful for solar cell.    ADVANTAGE - The method ensures economical and efficient etching back of a semiconductor layer of a substrate without any damage.    DETAILED DESCRIPTION - The method for partially etching back a semiconductor layer of a silicon substrate (3), comprises partially arranging the substrate in an etching solution (5), where areas of the semiconductor layer located outside the etching solution are partially removed by means of reactive vapors (11) originating from the etching solution, only up to a remaining residual thickness of the semiconductor layer. A doped semiconductor layer (1) and a silicon layer are etched back. The doped silicon layer is formed through applying dopant in the silicon substrate. The substrate is arranged so that the areas of the semiconductor layer exist in the etching solution and are completely removed by the etching solution. An emitter of a solar cell substrate is etched back. The solar cell substrate is arranged so that an emitter side of the solar cell substrate is present outside of the etching solution and one of the emitter sides is present opposite side of the solar cell substrate in the etching solution. A silicate glass layer present on the etched semiconductor layer is removed before the etching back of semiconductor layer using wet chemical method. The reactive vapors are partially removed for adjusting an etch back rate for the etching back of the semiconductor layer. An inert gas and/or a reactive gas are supplied to external of the etching solution for adjusting the etch back rate of the reactive vapor. Gaseous ozone and gaseous hydrogen fluoride are used as the reactive gas. The areas of the semiconductor layer located outside the etching solution are irradiated by UV light for adjusting the etch back rate. The substrate is completely arranged in an additional etching medium by which the semiconductor layer is partially etched back. The silicate glass layer is removed by the additional etching medium before the main etching step is carried out. An additional etching solution is used as the additional etching medium, which contains hydrofluoric acid, and ozone is introduced into the additional etching solution. An INDEPENDENT CLAIM is included for a device for partial etching back a semiconductor layer of a substrate.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a device for partially etching back a semiconductor layer of a substrate.    Doped semiconductor layer (1)    Substrate (3)    Etching solution (5)    Reactive vapors (11)    Etched back emitter. (15)