Multi-tier three-dimensional memory device with dielectric support pillars and methods for making the same

1. A semiconductor device, comprising:

at least one alternating stack of insulating layers and electrically conductive layers located over a substrate including a semiconductor material layer;

a memory opening vertically extending through a memory region of the at least one alternating stack in which each layer of the at least one alternating stack is present;

a memory opening fill structure located in the memory opening and comprising a memory film, and a semiconductor material portion in contact with the semiconductor material layer;

a support opening vertically extending through at least a bottommost one of the electrically conductive layers of the at least one alternating stack; and

a support pillar structure located in the support opening, wherein the support pillar structure lacks a semiconductor material portion which is in contact with the semiconductor material layer;

wherein:

the semiconductor material portion of the memory opening fill structure comprises a vertical semiconductor channel and a semiconductor pedestal channel portion located between the semiconductor material layer and a bottom of the vertical semiconductor channel;

the semiconductor pedestal channel portion contacts both the semiconductor material layer and the bottom of the vertical semiconductor channel;

the support pillar structure comprises a dummy vertical semiconductor channel which does not contact the semiconductor material layer;

the support pillar structure lacks the semiconductor pedestal channel portion located between the semiconductor material layer and a bottom of the dummy vertical semiconductor channel;

the support pillar structure comprises a dummy memory film having a same set layers as the memory film;

the vertical semiconductor channel is in contact with a sidewall and a recessed surface of the semiconductor material portion;

the dummy vertical semiconductor channel has a same material composition as the vertical semiconductor channel and contacts an inner sidewall of the dummy memory film; and

the dummy vertical semiconductor channel vertically extends through a bottom portion of the dummy memory film, and is spaced from the semiconductor material layer by a semiconductor oxide liner.

2. A semiconductor device, comprising:

at least one alternating stack of insulating layers and electrically conductive layers located over a substrate including a semiconductor material layer;

a memory opening vertically extending through a memory region of the at least one alternating stack in which each layer of the at least one alternating stack is present;

a memory opening fill structure located in the memory opening and comprising a memory film, and a semiconductor material portion in contact with the semiconductor material layer;

a support opening vertically extending through at least a bottommost one of the electrically conductive layers of the at least one alternating stack; and

a support pillar structure located in the support opening, wherein the support pillar structure lacks a semiconductor material portion which is in contact with the semiconductor material layer;

wherein:

the semiconductor material portion of the memory opening fill structure comprises a vertical semiconductor channel and a semiconductor pedestal channel portion located between the semiconductor material layer and a bottom of the vertical semiconductor channel;

the semiconductor pedestal channel portion contacts both the semiconductor material layer and the bottom of the vertical semiconductor channel;

the support pillar structure comprises a dummy vertical semiconductor channel which does not contact the semiconductor material layer;

the support pillar structure lacks the semiconductor pedestal channel portion located between the semiconductor material layer and a bottom of the dummy vertical semiconductor channel;

the semiconductor pedestal channel portion contacts a sidewall of a bottommost insulating layer of the at least one alternating stack, a sidewall of the semiconductor material layer, and a recessed surface of the semiconductor material layer located below a horizontal plane including an interface between the semiconductor material layer and the bottommost insulating layer of the at least one alternating stack;

the semiconductor pedestal channel portion has an annular bottom surface contacting a portion of a top surface of the semiconductor material layer;

the semiconductor pedestal channel portion has a first cylindrical sidewall that contacts the bottommost insulating layer of the at least one alternating stack; and

the semiconductor pedestal channel portion has a second cylindrical sidewall that contacts the semiconductor material layer.

3. The memory device of claim 2 , wherein:

a bottom periphery of the first cylindrical sidewall coincides with an outer periphery of the annular bottom surface;

a top periphery of the second cylindrical sidewall coincides with an inner periphery of the annular bottom surface; and

the outer periphery of the annular bottom surface is laterally offset outward from the inner periphery of the annular bottom surface by a uniform lateral offset distance around an entirety of the inner periphery of the annular bottom surface.

4. The memory device of claim 2 , further comprising a tubular dielectric spacer laterally surrounding the semiconductor pedestal channel portion and contacting a bottommost insulating layer of the at least one alternating stack, wherein a bottommost electrically conductive layer within the at least one alternating stack laterally surrounds the tubular dielectric spacer, wherein the tubular dielectric spacer comprises a thermal oxide of a semiconductor material of the semiconductor pedestal channel portion.

5. A semiconductor device, comprising:

at least one alternating stack of insulating layers and electrically conductive layers located over a substrate including a semiconductor material layer;

a memory opening vertically extending through a memory region of the at least one alternating stack in which each layer of the at least one alternating stack is present;

a memory opening fill structure located in the memory opening and comprising a memory film, and a semiconductor material portion in contact with the semiconductor material layer;

a support opening vertically extending through at least a bottommost one of the electrically conductive layers of the at least one alternating stack; and

a support pillar structure located in the support opening, wherein the support pillar structure lacks a semiconductor material portion which is in contact with the semiconductor material layer;

wherein the support pillar structure further comprises a semiconductor oxide liner that includes a dielectric oxide of a semiconductor material of the semiconductor material layer, and wherein an entire interface between the support pillar structure and the semiconductor material layer is a continuous interface between the semiconductor oxide liner and the semiconductor material layer.