Method for the formation and lift-off of porous silicon layers

A method for the manufacture of porous layers in a semiconductor substrate, comprising:

• applying a solution comprising negative Fluorine (F−) ions, suitable for removing material from said substrate, between a surface of said semiconductor substrate and an anode;
• applying a first current between said anode and a cathode of said semiconductor substrate a sufficient amount of time to obtain a low porosity layer at said surface and a high porosity layer positioned under said low porosity layer, wherein at least said low porosity layer has a thickness suitable for removal and transfer from said substrate.;
• and
• maintaining said solution and applying a second current a further amount of time so as to obtain lift-off of said low porosity layer and a portion of said high-porosity layer from said substrate.