Three-dimensional memory device with driver circuitry on the backside of a substrate and method of making thereof
A three-dimensional memory device includes an alternating stack of insulating layers and word lines located over a front side surface of a semiconductor substrate, memory stack structures extending through the alternating stack, in which each of the memory stack structures includes a memory film and a vertical semiconductor channel contacting an inner sidewall of the memory film, drain regions contacting a respective vertical semiconductor channel, bit lines electrically connected to the respective drain regions, driver circuitry for the memory stack structures located on a backside of the semiconductor substrate, and electrically conductive paths vertically extending through the semiconductor substrate and electrically connecting nodes of the driver circuitry to respective word lines or bit lines.
1. A three-dimensional memory device, comprising:
an alternating stack of insulating layers and word lines located over a front side surface of a semiconductor substrate;
memory stack structures extending through the alternating stack, wherein each of the memory stack structures comprises a memory film and a vertical semiconductor channel contacting an inner sidewall of the memory film;
drain regions contacting a respective vertical semiconductor channel;
bit lines electrically connected to the respective drain regions;
driver circuitry for the memory stack structures located on a backside of the semiconductor substrate; and
electrically conductive paths vertically extending through the semiconductor substrate and electrically connecting nodes of the driver circuitry to respective word lines or bit lines.
2. The three-dimensional memory device of claim 1 , wherein:
the driver circuitry comprises field effect transistors; and
each of the field effect transistors includes a respective channel that includes a portion of a backside surface of the semiconductor substrate and a respective gate electrode that is located below the backside surface of the semiconductor substrate.
3. The three-dimensional memory device of claim 2 , further comprising doped semiconductor wells located on, and above, the backside surface of the semiconductor surface and vertically spaced from the front side surface of the semiconductor substrate.
4. The three-dimensional memory device of claim 1 , further comprising:
front side dielectric material layers overlying the alternating stack and the memory stack structures;
front side metal interconnect structures embedded within the front side dielectric material layers; and
backside dielectric material layers underlying the driver circuitry; and
backside metal interconnect structures embedded within the backside dielectric material layers,
wherein at least one of the electrically conductive paths comprises a respective subset of the front side metal interconnect structures and a respective subset of the backside metal interconnect structures.
5. The three-dimensional memory device of claim 1 , wherein each of the electrically conductive paths comprises a respective through-substrate via structure that vertically extends through the semiconductor substrate from a front side surface of the semiconductor substrate to a backside surface of the semiconductor substrate.
6. The three-dimensional memory device of claim 5 , wherein each of the through-substrate via structures has a taper such that a horizontal cross-sectional shape has a greater area in proximity to the front side surface of the semiconductor substrate than in proximity to the backside surface of the semiconductor substrate.
7. The three-dimensional memory device of claim 5 , wherein:
the alternating stack includes a stepped surface region in which a lateral extent of the word lines decreases with a vertical distance from the front side surface of the semiconductor substrate to form stepped surfaces; and
a retro-stepped dielectric material portion is located on the stepped surfaces and over the semiconductor substrate.
8. The three-dimensional memory device of claim 7 , wherein each of the through-substrate via structures contacts a through-dielectric via structure that extends through the retro-stepped dielectric material portion and contacts a respective front side metal interconnect structure that overlies the retro-stepped dielectric material portion.
9. The three-dimensional memory device of claim 1 , wherein the semiconductor substrate comprises a single crystalline silicon wafer.
10. The three-dimensional memory device of claim 1 , further comprising a planar semiconductor material layer overlying the front side of the semiconductor substrate and underlying the alternating stack and electrically shorted to bottom ends of the vertical semiconductor channels of the memory stack structures.
11. The three-dimensional memory device of claim 10 , further comprising a dielectric spacer material layer overlying the front side of the semiconductor substrate and underlying the planar semiconductor material layer and electrically isolating the planar semiconductor material layer from the semiconductor substrate.
12. The three-dimensional memory device of claim 1 , wherein:
the three-dimensional memory device comprises a monolithic three-dimensional NAND memory device;
the semiconductor substrate comprises a silicon substrate;
the monolithic three-dimensional NAND memory device comprises an array of monolithic three-dimensional NAND strings over the silicon substrate;
at least one memory cell in a first device level of the array of monolithic three-dimensional NAND strings is located over another memory cell in a second device level of the array of monolithic three-dimensional NAND strings;
the word lines have a strip shape extending substantially parallel to the front side surface of the semiconductor substrate; and
the array of monolithic three-dimensional NAND strings comprises:
a plurality of semiconductor channels located including a respective one of the vertical semiconductor channels, and
a plurality of charge storage elements embodied as portions of the memory films, each charge storage element located adjacent to a respective one of the vertical semiconductor channels.