Patent ID: 8278183
Filing Date: 2012-10-02
Classification: H01L

Abstract:
1. A method for producing isolation trenches having different sidewall dopings on a silicon-based substrate wafer for use in a trench-isolated smart power technology, the method comprising: forming a first trench having a first width and a second trench having a second width that is larger than the first width using a hard mask, the first trench and the second trench having sidewalls; first doping the sidewalls of the first and the second trenches using a first doping to produce sidewalls of a first doping; depositing a material layer having a given thickness which is selected such that the first trench is filled completely up to and beyond the hard mask and that a gap remains in the second trench; isotropic etching of the material layer, thereby removing the material layer from the second trench while keeping a residue of the material layer in the first trench; performing a further doping of the sidewalls of one of the first trench and the second trench in the presence of the residue of the material layer in the first trench.