The present invention provides an integrated circuit device that include a semiconductor substrate having a semiconductor region of first conductivity type therein extending adjacent the surface of the substrate. The device further includes an electrically insulating layer with a contact hole in it that exposes the semiconductor region of first conductivity type on the surface of the semiconductor substrate. The device still further includes a poly-Si.sub.1-x Ge.sub.x conductive plug of first conductivity type that extends in the contact hole and is electrically connected to the semiconductor region of first conductivity type is provided.

In a vapor-phase growth method in which a silicon-germanium mixed crystal layer is deposited on a semiconductor substrate, the vapor-phase growth method comprises a first step of introducing silicon raw material gas into a reaction furnace in such a manner that a silicon raw material gas partial pressure increases in proportion to a time to thereby deposit a first semiconductor layer of a silicon layer on the semiconductor substrate under reduced pressure, a second step of introducing silicon raw material gas and germanium raw material gas into the reaction furnace in such a manner that a desired germanium concentration may be obtained to thereby deposit a second semiconductor layer of a silicon-germanium mixed crystal layer on the first semiconductor layer under reduced pressure and a third step of introducing silicon raw material gas into the reaction furnace under reduced pressure to thereby deposit a third semiconductor layer of a silicon layer on the second semiconductor layer. Thus, there can be obtained a semiconductor layer in which a misfit dislocation can be improved.

In a vapor-phase growth method in which a silicon-germanium mixed crystal layer is deposited on a semiconductor substrate, the vapor-phase growth method comprises a first step of introducing silicon raw material gas into a reaction furnace in such a manner that a silicon raw material gas partial pressure increases in proportion to a time to thereby deposit a first semiconductor layer of a silicon layer on the semiconductor substrate under reduced pressure, a second step of introducing silicon raw material gas and germanium raw material gas into the reaction furnace in such a manner that a desired germanium concentration may be obtained to thereby deposit a second semiconductor layer of a silicon-germanium mixed crystal layer on the first semiconductor layer under reduced pressure and a third step of introducing silicon raw material gas into the reaction furnace under reduced pressure to thereby deposit a third semiconductor layer of a silicon layer on the second semiconductor layer. Thus, there can be obtained a semiconductor layer in which a misfit dislocation can be improved.

The present invention provides integrated circuit devices that include a semiconductor substrate having a semiconductor region of first conductivity type therein extending adjacent the surface of the substrate. The device further includes an electrically insulating layer with a contact hole in it that exposes the semiconductor region of first conductivity type on the surface of the semiconductor substrate. The device still further includes a poly-Si.sub.1-xGe.sub.x conductive plug of first conductivity type that extends in the contact hole and is electrically connected to the semiconductor region of first conductivity type is provided. Related methods of fabricating integrated circuit devices are also provided.

A structure of a DRAM and a manufacturing process therefor, suitable for a substrate on which a plurality of word lines and a plurality of source/drain regions on sides of each of these word lines are formed. A plurality of bit line contacts and a plurality of node contacts are formed in electric contact with the source/drain regions. A first patterned insulating layer is formed on the substrate, in which a plurality of openings are formed in the insulating layer to expose the bit line contacts. The substrate is covered with a first conductive layer and a second insulating layer in sequence. The second insulating layer, the first conductive layer and the first insulating layer are patterned in sequence to form a plurality of bit line stacked structures and a plurality of bit lines electrically connecting to the bit contacts, exposing the node contacts. As a result, the bit line stacked structure forms a plurality of trenches and the bit line stacked structure is orthogonal to the word lines. A plurality of spacers are formed on sidewalls of the bit line stacked structure. A plurality of second conductive layers are formed conformal to the surfaces of the trenches. The second conductive layers are patterned to form a plurality of bottom electrodes electrically connected to the node contacts.