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1. (WO2018084928) BULB-SHAPED MEMORY STACK STRUCTURES FOR DIRECT SOURCE CONTACT IN THREE-DIMENSIONAL MEMORY DEVICE

Pub. No.:    WO/2018/084928    International Application No.:    PCT/US2017/050367
Publication Date: Sat May 12 01:59:59 CEST 2018 International Filing Date: Fri Sep 08 01:59:59 CEST 2017
IPC: H01L 27/11582
H01L 27/11573
Applicants: SANDISK TECHNOLOGIES LLC
Inventors: YU, Jixin
KITAMURA, Kento
ZHANG, Tong
GE, Chun
ZHANG, Yanli
SHIMIZU, Satoshi
KASAGI, Yasuo
OGAWA, Hiroyuki
MAO, Daxin
YAMAGUCHI, Kensuke
ALSMEIER, Johann
KAI, James
MATSUMOTO, Kazuyo
MASAMORI, Yohei
Title: BULB-SHAPED MEMORY STACK STRUCTURES FOR DIRECT SOURCE CONTACT IN THREE-DIMENSIONAL MEMORY DEVICE
Abstract:
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.