Patent ID: 9496135
Filing Date: 2016-11-15
CPC Classification: H01L

Claim Text:
1. An epitaxial silicon wafer comprising: a doped bulk wafer; a first inter-layer formed directly on the doped bulk wafer; a first epitaxial layer formed directly on the first inter-layer, the first epitaxial layer having a doping concentration higher than that of the doped bulk wafer; a second inter-layer formed directly on the first epitaxial layer; and a second epitaxial layer formed directly on the second inter-layer, and the second epitaxial layer having a doping concentration less than that of the first epitaxial layer, wherein the bulk wafer, the first inter-layer, the first epitaxial layer, the second inter-layer, and the second epitaxial layer have a same conductivity type, wherein both the first inter-layer and the second inter-layer have a different concentration from the first epitaxial layer and the second epitaxial layer, and wherein both the first inter-layer and the second inter-layer have a concentration higher than that of the doped bulk wafer.