Abstract: A sealing structure includes a first connector body having a groove, a second connector body encompassing the first connector body, an O-ring partially received in the groove of the first connector body, and a variable back-up ring partially received in the groove of the first connector body and holding the O-ring. The variable back-up ring is deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.

Abstract: A wafer manufacturing method, an epitaxial wafer manufacturing method, and a wafer and epitaxial wafer manufactured thereby, are provided. The wafer manufacturing method enables the manufacture of a wafer with a low density of micropipe defects and minimum numbers of particles and scratches. The epitaxial wafer manufacturing method enables the manufacture of an epitaxial wafer that has low densities of defects such as downfall, triangular, and carrot defects, exhibits excellent device characteristics, and improves the yield of devices.

Abstract: A wafer manufacturing method, an epitaxial wafer manufacturing method, and a wafer and epitaxial wafer manufactured thereby, are provided. The wafer manufacturing method enables the manufacture of a wafer with a low density of micropipe defects and minimum numbers of particles and scratches. The epitaxial wafer manufacturing method enables the manufacture of an epitaxial wafer that has low densities of defects such as downfall, triangular, and carrot defects, exhibits excellent device characteristics, and improves the yield of devices.

Abstract: A variable back-up ring includes: a first half shell; a second half shell having a symmetrical shape to the first half shell; and an inner cavity defined by the first half shell and the second half shell. The first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.

Abstract: A hydrogen supply apparatus is provided. The apparatus includes a first connecting member having a first flow path through which hydrogen is supplied and a second connecting member connected to the first connecting member and having a second flow path that communicates with the first flow path. A back-up ring has a first packing portion abutting an inner surface of the first connecting member, a second packing portion abutting an outer surface of the second connecting member, and a connecting portion connecting ends of the first packing portion and the second packing portion. An elastic member is elastically compressible and expandable between the first and second packing portions.