Epitaxially coated semiconductor wafer and process for producing it

• Main Authors: Siebert, Wolfgang, Wenski, Guido, Messmann, Klaus, Heier, Gerhard, Altmann, Thomas, Furfanger, Martin
• Format: Patent
• Language: English
• Published: 02.10.2003

A semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface. In the semiconductor wafer, the epitaxial layer has a maximum local flatness value SFQR max of less than or equal to 0.13 m and a maximum density of 0.14 scattered light centers per cm 2 . The front surface of the semiconductor wafer, prior to the deposition of the epitaxial layer, has a surface roughness of 0.05 to 0.29 nm RMS, measured by AFM on a 1 m×1 m reference area. Furthermore, there is a process for producing the semiconductor wafer. The process includes the following process steps: (a) as a single polishing step, simultaneous polishing of the front surface and of the back surface of the semiconductor wafer between rotating polishing plates while an alkaline polishing sol is being supplied, the semiconductor wafer lying in a cutout of a carrier whose thickness is dimensioned to be 2 to 20 m less than the thickness of the semiconductor wafer after the latter has been polished; (b) simultaneous treatment of the, front surface and of the back surface of the semiconductor wafer between rotating polishing plates while a liquid containing at least one polyhydric alcohol having 2 to 6 carbon atoms is being supplied; (c) cleaning and drying of the semiconductor wafer; and (d) deposition of the epitaxial layer on the front surface of the semi-conductor wafer produced in accordance with steps (a) to (c).