Epitaxially coated semiconductor wafer and process for producing it

• Main Authors: WENSKI, GUIDO, MESSMANN, KLAUS, ALTMANN, THOMAS, HEIER, GERHARD, SIEBERT, WOLFGANG DR
• Format: Patent
• Language: English
• Published: 21.04.2003
• Edition: 7
• Subjects: AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR; BASIC ELECTRIC ELEMENTS; CHEMISTRY; CRYSTAL GROWTH; DRESSING OR CONDITIONING OF ABRADING SURFACES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS; GRINDING; MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; METALLURGY; PERFORMING OPERATIONS; POLISHING; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; REFINING BY ZONE-MELTING OF MATERIAL; SEMICONDUCTOR DEVICES; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; SINGLE-CRYSTAL-GROWTH; TRANSPORTING; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL

The invention relates to a semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface. The semiconductor wafer is characterized by the fact that the epitaxial layer has a maximum local flatness value SFQRmax of less than or equal to 0.13 m and a maximum density of 0.14 scattered light centers per cm2, and 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 x 1 m reference area. Furthermore, the invention relates to a process for producing the semiconductor wafer. The process comprises the following process steps: (a) as a single polishing step, simultaneous polishing of the front surface and of the rear surface of the semiconductor wafer between rotating polishing plates while an alkaline polishing sol is being supplied, the semiconductor wafer lying in a cutout in 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 semiconductor wafer produced in accordance with steps (a) to (c).