Sandisk Technologies Inc.

Kento Kitamura

Hiroyuki Ogawa

Satoshi Shimizu

Yasuo Kasagi

Johann Alsmeier

Yanli Zhang

James K Kai

Tong Zhang

Jixin Yu

Daxin Mao

Kensuke Yamaguchi

Chun Ge

The contact area between a source strap structure of a buried source layer and semiconductor channels within memory structures can be increased by laterally expanding a source-level volume in which the memory stack structures are formed. In one embodiment, sacrificial semiconductor pedestals can be formed in source-level memory openings prior to formation of a vertically alternating stack of insulating layers and sacrificial material layers. Memory openings can include bulging portions formed by removal of the sacrificial semiconductor pedestals. Memory stack structures can be formed with a greater sidewall surface area in the bulging portions to provide a greater contact area with the source strap structure. Alternatively, bottom portions of memory openings can be expanded selective to upper portions during, or after, formation of the memory openings to provide bulging portions and to increase the contact area with the source strap structure.

Bulb-shaped memory stack structures for direct source contact in three-dimensional memory device

A layer stack including a lower semiconductor layer, a lower dielectric layer, and a spacer material layer is formed over a semiconductor substrate, and the spacer material layer is patterned to form spacer line structures. An upper dielectric layer and an upper semiconductor layer are formed, followed by formation of an alternating stack of insulating layers and spacer material layers. Memory stack structures are formed through the alternating stack, the upper semiconductor layer, and the dielectric material layer. The upper semiconductor layer, the upper dielectric layer, and the lower semiconductor layer can be patterned to form a buried source layer and at least one passive device. Each passive device can include a lower semiconductor plate, a dielectric material plate, and an upper semiconductor plate. Each passive device can be a resistor or a capacitor.

Three-dimensional memory device having passive devices at a buried source line level and method of making thereof

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Yokkaichi, Japan

Kento Kitamura