Abstract: A semiconductor device includes a substrate including a circuit region and a cell region. The cell region includes a gate stacking structure, a channel structure that extends into the gate stacking structure and is on the cell array region, a through-gate contact portion that extends into the gate stacking structure and is electrically connected to a connection gate electrode, and an upper gate contact portion that is electrically connected to an upper gate electrode, where the upper gate electrode is separated from the substrate by a first distance, the connection gate electrode is separated from the substrate by a second distance, and where the second distance is less than the first distance, and where the upper gate contact portion includes a first portion and a second portion, and a boundary between the first portion and the second portion has a step shape.

Abstract: The present invention relates to a process for preparing isobutene-cyclodiene copolymers having a number-average molecular weight of at least 100,000 and an unsaturation of 1.about.30% by mol, characterized in that polymerization is carried out without gelation by reacting 75.about.99.5% by weight of an isobutene and 0.5.about.25% by weight of a cyclodiene or a mixture of cyclodiene as reaction materials, in a polar reaction solvent of 1.about.10 times by weight with respect to the reaction materials, wherein a catalyst solution of 0.02.about.2% by weight in the polar solvent is used in the amount of 0.2.about.2 times by weight with respect to the reaction materials, at a reaction temperature of -100.degree..about.-85.degree. C., thereby obtaining a copolymer, and then removing the residual catalyst activity at a temperature of -100.degree..about.-25.degree. C.