A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, an array of memory opening fill structures located within an array of memory openings vertically extending through the alternating stack, and a drain-select-level isolation structure vertically extending through drain-select-level electrically conductive layers between two rows of memory opening fill structures. The drain-select-level isolation structure may comprise a low-k dielectric material or an air gap.

A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, an array of memory opening fill structures located within an array of memory openings vertically extending through the alternating stack, and a drain-select-level isolation structure vertically extending through drain-select-level electrically conductive layers between two rows of memory opening fill structures. The drain-select-level isolation structure may comprise a low-k dielectric material or an air gap.

Semiconductor devices having improved source/drain features and methods for fabricating such are disclosed herein. An exemplary device includes a semiconductor layer stack disposed over a mesa structure of a substrate. The device further includes a metal gate disposed over the semiconductor layer stack and an inner spacer disposed on the mesa structure of the substrate. The device further includes a first epitaxial source/drain feature and a second epitaxial source/drain feature where the semiconductor layer stack is disposed between the first epitaxial source/drain feature and the second epitaxial source/drain feature. The device further includes a void disposed between the inner spacer and the first epitaxial source/drain feature.

Semiconductor devices having improved source/drain features and methods for fabricating such are disclosed herein. An exemplary device includes a semiconductor layer stack disposed over a mesa structure of a substrate. The device further includes a metal gate disposed over the semiconductor layer stack and an inner spacer disposed on the mesa structure of the substrate. The device further includes a first epitaxial source/drain feature and a second epitaxial source/drain feature where the semiconductor layer stack is disposed between the first epitaxial source/drain feature and the second epitaxial source/drain feature. The device further includes a void disposed between the inner spacer and the first epitaxial source/drain feature.

A semiconductor device and a method of fabricating a semiconductor device, the device including a substrate; a first conductive pattern on the substrate; a second conductive pattern on the substrate and spaced apart from the first conductive pattern; an air spacer between the first conductive pattern and the second conductive pattern; and a quantum dot pattern covering an upper part of the air spacer.

A semiconductor device and a method of fabricating a semiconductor device, the device including a substrate; a first conductive pattern on the substrate; a second conductive pattern on the substrate and spaced apart from the first conductive pattern; an air spacer between the first conductive pattern and the second conductive pattern; and a quantum dot pattern covering an upper part of the air spacer.

The present disclosure provides a method for preparing a semiconductor memory device with air gaps between conductive features. The method includes forming an isolation layer defining a first active region in a substrate; forming a first doped region in the first active region; forming a first word line buried in a first trench adjacent to the first doped region; and forming a high-level bit line contact positioned on the first doped region; forming a first air gap surrounding the high-level bit line contact. The forming of the first word line comprises: forming a lower electrode structure and an upper electrode structure on the lower electrode structure. The forming of the upper electrode structure comprises: forming a source layer substantially covering a sidewall of the first trench; forming a conductive layer on the source layer; and forming a work-function adjustment layer disposed between the source layer and the conductive layer.

A semiconductor device includes a semiconductor substrate, a semiconductor layer, a first insulating film, and a conductive film. The semiconductor layer is formed on the semiconductor substrate. A first trench reaching the semiconductor substrate is formed within the semiconductor layer. The first insulating film is formed on the inner side surface of the first trench such that a portion of the semiconductor substrate is exposed in the first trench. The conductive film is electrically connected with the semiconductor substrate and formed on the inner side surface of the first trench through the first insulating film. In plan view, a first length of the first trench in an extending direction of the first trench is greater than a second length of the first trench in a width direction perpendicular to the extending direction, and equal to or less than 30 μm.

A semiconductor device includes a semiconductor substrate, a semiconductor layer, a first insulating film, and a conductive film. The semiconductor layer is formed on the semiconductor substrate. A first trench reaching the semiconductor substrate is formed within the semiconductor layer. The first insulating film is formed on the inner side surface of the first trench such that a portion of the semiconductor substrate is exposed in the first trench. The conductive film is electrically connected with the semiconductor substrate and formed on the inner side surface of the first trench through the first insulating film. In plan view, a first length of the first trench in an extending direction of the first trench is greater than a second length of the first trench in a width direction perpendicular to the extending direction, and equal to or less than 30 μm.

A semiconductor device includes a substrate. A gate structure is disposed over the substrate in a vertical direction. The gate structure extends in a first horizontal direction. An air spacer is disposed adjacent to a first portion of the gate structure in a second horizontal direction that is different from the first horizontal direction. The air spacer has a vertical boundary in a cross-sectional side view defined by the vertical direction and the first horizontal direction.