Sandisk Technologies Inc.

Keita Kumamoto

Takuya Futase

Tomoyasu Kakegawa

Yuji Takahashi

Noritaka Fukuo

Katsuo Yamada

Hidehito Koseki

Hidetoshi Nakamoto

Hirotada Tobita

Shunsuke Akimoto

Masato Noguchi

An initial etch forms a trench over first contact areas of a plurality of NAND strings, the initial etch also forming individual openings over second contact areas of the plurality of NAND strings. Material is added in the trench to reduce an area of exposed bottom surface of the trench while maintaining the individual openings without substantial reduction of bottom surface area. Subsequent further etching extends the trench and the plurality of individual openings.

Source line formation and structure

Contact holes are constrained to their designated active areas by etch-resistant walls so that they cannot contact adjacent active areas. Etch-resistant walls provide outer limits for any contact hole bending that may occur and thus keep contact holes substantially vertical. Mask openings for contact hole formation may be large so that they overlap etch-resistant walls.

Contact hole collimation using etch-resistant walls

Contact holes of different depths for source, drain, and gate connections are formed by common etch steps using a relatively low etch rate material over the gate electrode and a relatively high etch rate material over the source and drain terminals to provide similar etch times for all three holes so that risk of over-etching is reduced.

Bi-level dry etching scheme for transistor contacts

Growing community of inventors

Mie, Japan

Keita Kumamoto