Patent ID: 8304345

Claim:
A method for polishing a heteroepitaxial structure having at least one surface layer of germanium, which comprises: a first step of chemical-mechanical polishing of the surface of the germanium layer carried out with a first polishing solution having an acidic pH and silica particles having a diameter between 40 nm and 60 nm and also with a polishing fabric having a first compressibility factor of between 2% and 4%, and a second step of chemical-mechanical polishing of the surface of the germanium layer with a second polishing solution having an alkaline pH and silica particles having a diameter between 30 nm and 40 nm and also with a polishing fabric having a second compressibility factor of between 5% and 9%, wherein after the second chemical-mechanical polishing step, the germanium layer has a surface microroughness of less than 0.1 nm RMS for a roughness measurement carried out using an atomic force microscope on scan areas of 2*2 μm 2 and 10*10 μm 2 .