>160 and the conductive layer 103 of the memory array stack 102A. The memory cell is electrically connected to the pillar element 130. The conductive pillar 163 is electrically connected to the memory cell and can be functioned as a bit line used to control the memory cell. The conductive layers 103 of the memory array stack 102A and the conductive stair layers 105 of the staircase stack 102B can be functioned as word lines electrically connected to the memory cells. The transistor switch formed by the conductive film 123, the dielectric element 132 an the channel element 133 can be functioned as a word line switch electrically connected to the memory cell.

In an embodiment, the memory device 10 includes a driving circuitry, such as a CMOS circuitry, in an area below the substrate 101. The driving circuitry and stack structure 102 may be on opposite sides of the substrate 101.

FIG. 1A illustrates a stack structure (e.g. the stack structure 102), but the present disclosure is not limited thereto. The memory device may include one or more stack structures as shown in FIG. 1C. FIG. 1C illustrates a schematic stereoscopic view of a memory device 10′ including stack structures according to another embodiment of the present disclosure.

The memory device 10′ includes a stack structure 102 and a stack structure 102′. The stack structure 102 may be adjacent to the stack structure 102′. The stack structure 102 and the stack structure 102′ can be disposed along the third direction D3. The stack structure 102′ includes a conductive film 123 and a conductive film 123′. The conductive film 123 can be adjacent to the conductive film 123′. The conductive film 123 and the conductive film 123′ can be disposed along the third direction D3. In this embodiment, the memory device 10′ include a trench 170 and a trench 171. The trench 170 extends along the second direction D2. The stack structure 102 is separated from the stack structure 102′ by the trench 170. The trench 171 extends along the second direction D2. The conductive film 123 is separated from the conductive film 123′ by the trench 171. In an embodiment, insulating materials can be filled in the trench 170 and the trench 171 to form insulating strips. The structure of the stack structure 102′ may be similar to the structure of the stack structure 102. The memory array stack 102A of the stack structure 102 may be adjacent to the memory array stack of the stack structure 102′. The staircase stack 102B of the stack structure 102 may be adjacent to the staircase stack 102B′ of the stack structure 102′. In the first direction D1, the conductive film 123 may overlap the staircase stack 102B of the stack structure 102, and the conductive film 123′ may overlap the staircase stack 102B′ of the stack structure 102′.

Similar to the memory device 10, the memory device 10′ further includes a substrate, an insulating material film, insulating films on the stack structure 102 and the stack structure 102′, at least one pillar element 130, at least one contact pillar 151, wires 152 and at least one pillar structure 160. The structures of the substrate, the insulating material film, the insulating films on the stack structure 102 and the stack structure 102′, and the pillar structure 160 can be similar to the structures of the substrate 101, the insulating material film 108, the insulating films 121, 122, 124, 125 and 126, and the pillar structure 160 of the memory device 10 respectively, as shown in FIGS. 1A and 1B. The pillar element 130 on the stack structure 102 can be electrically connected to the pillar element 130 on the stack structure 102′. The conductive pillar 163 of the pillar structure 160 in the stack structure 102 can be electrically connected to the conductive pillar 163 of the pillar structure 160 in the stack structure 102′. The memory device 10′ has a higher storage density.

In other embodiments, the memory device of the present disclosure includes more than two stack structures, and the structure of the memory device can be illustrated by analogy with the memory device 10 and the memory device 10′ shown in in FIGS. 1A to 1C.

Referring to FIGS. 1D and 1E, FIG. 1D illustrates a schematic cross-sectional view of a memory device 20 according to an embodiment of the present disclosure, and FIG. 1E illustrates a schematic stereoscopic view of the memory device 20 according to an embodiment of the present disclosure. To keep the illustration simple and clear, some elements shown in FIG. 1D are omitted in FIG. 1E, and the numbers of the same components in FIGS. 1D and 1E may be different. The memory device 20 may be a three-dimensional ovonic threshold switch (OTS) memory. The differences between the memory device 20 shown in FIGS. 1D to 1E and the memory device 10 shown in FIGS. 1A to 1B are described below. The memory device 20 includes pillar structures 160. A portion of the pillar structures 160 passes through the staircase stack 102B, and another portion of the pillar structures 160 passes through the memory array stack 102A. The pillar structures 160 in the staircase stack 102B may be electrical floating, and therefore regarded as dummy pillar structures. The pillar structures 160 can be used as a support element. The pillar structures 160 in the memory array stack 102A may not passes through the insulating films 121, 122, 124 and 125. The contact pillar 151 extends along the first direction D1 and passes through the insulating films 121, 122, 124, 125 and 126. The contact pillar 151 is electrically connected to the pillar structure 160 in the memory array stack 102A. In the present embodiment, the upper surface of the pillar structure 160 (or the upper surface of the landing pad 168) is lower than the lower surface 123L of the conductive film 123 in the first direction D1. The pillar element 130′ of the memory device 20 includes a first pillar portion 130A, a second pillar portion 130B′ and a third pillar portion 130C. The second pillar portion 130B′ includes a dielectric element 132, a channel element 133′, a dielectric pillar 134 and a pad 135. The material of the channel element 133′ of the second pillar portion 130B′ of the memory device 20 can be different from or the same as the material of the channel element 133 of the second pillar portion 130B of the memory device 10.

The following descriptions will take the memory device 10 of FIGS. 1A to 1B as an example to illustrate a method for operating a memory device according to an embodiment of the present disclosure. The method for operating the memory device 10 may include the steps of selecting a specific memory cell from memory cells in the memory device 10 and turning on the selected memory cell, and the operation procedures of reading (READ operation procedure), programming (or can be understood as SET operation procedure) or erasing (or can be understood as RESET operation procedure) can be performed to the selected memory cell. The method for operating the memory device 10 may include the step of turning off the unselected memory cells of the memory cells in the memory device 10.

The step of turning on the selected memory cell includes: applying a word line voltage to a word line of the plurality of word lines (such as the conductive layers 103 of the memory array stack 102A and the conductive stair layers 105 of the staircase stack 102B) electrically connected to a selected memory cell of the memory cells, applying a control voltage to a word line switch of the plurality of word line switches (such as the transistor switches formed by the conductive films 123, the dielectric elements 132 and the channel elements 133) electrically connected to the selected memory cell, and applying a bit line voltage to a bit line of the plurality of bit lines (such as the conductive pillars 163) electrically connected to the selected memory cell to turn on the selected memory cell. Applying the control voltage to the word line switch electrically connected to the selected memory cell causes the word line electrically connected to the selected memory cell to be turned on. Applying the control voltage to the word line switch electrically connected to the selected memory cell will not cause the plurality of bit lines to be turned on or turned off since the conductive pillar 163 of the memory device 10 does not pass through the conductive film 123. In the method for operating the memory device 10, applying the control voltage to the word line switch will not simultaneously change the conductive state (ON or OFF state) of the word line switch and the bit line. The word line switch and bit line can be controlled independently.

The step of turning off the unselected memory cell includes: applying a ground voltage to word lines of the plurality of word lines (such as the conductive layers 103 of the memory array stack 102A and the conductive stair layers 105 of the staircase stack 102B) electrically connected to unselected memory cells of the memory cells, apply a ground control voltage to word line switches of the plurality of word line switches (such as the transistor switches formed by the conductive films 123, the dielectric elements 132 and the channel elements 133) electrically connected to the unselected memory cells, and applying a ground voltage to bit lines of the plurality of bit lines (such as the conductive pillars 163) electrically connected to the unselected memory cells to turn off the unselected memory cells.

For example, the memory device of the present disclosure can be operated by applying the voltages listed in TABLE 1 to the memory device. As shown in TABLE 1, in RESET operation procedure, ½Vs (bit line voltage) is applied to the bit line electrically connected to the selected memory cell, −½Vs (word line voltage) is applied to the word line electrically connected to the selected memory cell, and Vs+1 (control voltage) is applied to the word line switch electrically connected to the selected memory cell to turn on the selected memory cell; 0 V (ground voltage) can be applied to bit lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word line switches electrically connected to the unselected memory cells to turn off the unselected memory cells. As shown in TABLE 1, in SET operation procedure, −½Vs (bit line voltage) is applied to the bit line electrically connected to the selected memory cell, ½Vs (word line voltage) is applied to the word line electrically connected to the selected memory cell, and Vs+1 (control voltage) is applied to the word line switch electrically connected to the selected memory cell to turn on the selected memory cell; 0 V (ground voltage) can be applied to bit lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word line switches electrically connected to the unselected memory cells to turn off the unselected memory cells. As shown in TABLE 1, in READ operation procedure, ½Vr (bit line voltage) is applied to the bit line electrically connected to the selected memory cell, −½Vr (word line voltage) is applied to the word line electrically connected to the selected memory cell, and Vs+1 or Vr+1 (control voltage) is applied to the word line switch electrically connected to the selected memory cell to turn on the selected memory cell; 0 V (ground voltage) can be applied to bit lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word lines electrically connected to the unselected memory cells, 0 V (ground voltage) can be applied to the word line switches electrically connected to the unselected memory cells to turn off the unselected memory cells. Vs can be between 2.5 V and 9 V, for example, Vs is 5 V. Vr can be between 1 V and 6 V, for example, Vr is 3 V. As shown in TABLE 1, the bias direction of the voltage (e.g. first bit line voltage; ½Vs) applied to the bit line electrically connected to the selected memory cell in RESET operation procedure is opposite to the bias direction of the voltage (e.g. second bit line voltage; −½Vs) applied to the bit line electrically connected to the selected memory cell in SET operation procedure. The bias direction of the voltage (e.g. word line voltage; −½Vs) applied to the word line electrically connected to the selected memory cell in RESET operation procedure is opposite to the bias direction of the voltage (e.g. word line voltage; ½Vs) applied to the word line electrically connected to the selected memory cell in SET operation procedure.

TABLE 1

RESET
SET
READ

bit line electrically connected
½
Vs
−½
Vs
½
Vr

to the selected memory cell

bit lines electrically
0
V
0
V
0
V

connected to the unselected

memory cells

word line electrically
−½
Vs
½
Vs
−½
Vr

connected to the selected

memory cell

word lines electrically
0
V
0
V
0
V

connected to the unselected

memory cells

word line switch electrically
Vs + 1
Vs + 1
Vs + 1

connected to the selected

or

memory cell

Vr + 1

word line switches
0
V
0
V
0
V

electrically connected to the

unselected memory cells

The memory device of the present disclosure does not include a bit line switch that shares a control electrode with the word line switch, so that applying a voltage to the control electrode of the word line switch during the operation of the memory device will not affect the conductive state (ON or OFF state) of the bit line. By applying voltages to the bit line, word line and word plane (word line switch) respectively, specific memory cell in the memory device can be selected, and the operation procedures of reading (READ), programming (or can be understood as SET operation procedure) or erasing (or can be understood as RESET operation procedure) can be performed to the selected memory cell.

FIGS. 2 to 16 illustrate a method for manufacturing a memory device according to an embodiment of the present disclosure.

Referring to FIG. 2, FIG. 2 shows one stage of the method for manufacturing the memory device. A substrate 101 is provided. Conductive material layers 203 and insulating material layers 204 stacked alternately along the first direction D1 are formed on an upper surface 101U of the substrate 101. The first direction D1 may be the normal direction of the upper surface 101U of the substrate 101. In an embodiment, the conductive material layers 203 and insulating material layers 204 are formed on the upper surface 101U of the substrate 101 through a deposition process. The thickness of the lowest insulating material layer 204 among the insulating material layers 204 in the first direction D1 may be greater than the thickness of the other insulating material layer 204 in the first direction D1. The topmost insulating material layer 204 among the insulating material layers 204 may be a hard mask layer. The substrate 101 may include a doped or undoped semiconductor material, a dielectric material or a conductive material. In an embodiment, the substrate 101 is a doped or undoped silicon substrate. In an embodiment, the substrate 101 is an intermetal dielectric layer (IMD) formed through back end of line process (BEOL) or an interlayer dielectric layer (ILD). The conductive material layer 203 may include a conductive material, such as carbon, titanium nitride, highly doped polycrystalline silicon (such as N+ polycrystalline silicon or P+ polycrystalline silicon), tantalum nitride, cobalt, silicon germanium alloy (SiGe_x), ruthenium, nickel or aluminum. The insulating material layer 204 may include oxide such as silicon oxide.

Referring to FIG. 3, FIG. 3 shows one stage of the method for manufacturing the memory device. A stack structure 102 is formed on the substrate 101. In an embodiment the conductive material layers 203 and the insulating material layers 204 shown in FIG. 2 are patterned through an etching process so as to form the stack structure 102 including a memory array stack 102A and a staircase stack 102B. A portion of the conductive material layer 203 defined in the memory array stack 102A is the conductive layer 103. A portion of the conductive material layer 203 defined in the staircase stack 102B is the conductive stair layer 105. A portion of the insulating material layer 204 defined in the memory array stack 102A is the insulating layer 104. A portion of the insulating material layer 204 defined in the staircase stack 102B is the insulating stair layers 106.

Referring to FIG. 4, FIG. 4 shows one stage of the method for manufacturing the memory device. An insulating material film 108 is formed on the stack structure 102. In an embodiment, the insulating material film 108 is formed on the stack structure 102 through a deposition process. The insulating material film 108 may include oxide such as silicon oxide.

Referring to FIG. 5, FIG. 5 shows one stage of the method for manufacturing the memory device. First pillar portions 130A are formed. The first pillar portions 130A are arranged separately from each other on the staircase stack 102B. The first pillar portion 130A extends along the first direction D1 and passes through the insulating material film 108. The first pillar portion 130A is electrically connected to the conductive stair layer 105 of the staircase stack 102B. In an embodiment, a portion of the staircase stack 102B and a portion of the insulating material film 108 are removed through an etching process to form holes 560. The holes 560 are arranged separately from each other in the insulating material film 108. The sidewalls of the insulating material film 108 and the upper surfaces of the conductive stair layers 105 are exposed by the holes 560. A conductive material may be filled in the holes 560 through a deposition process to form the first pillar portions 130A. The conductive material of the first pillar portion may include tungsten. In an embodiment, a barrier film can be formed on the sidewall of the insulating material film 108 exposed by the hole 560 through a deposition process before the conductive material is filled in the hole 560. The barrier layer may include titanium nitride. In an embodiment, a planarization process, such as a chemical-mechanical planarization process, can be performed to the conductive material after the conductive material is filled in the holes 560.

Referring to FIG. 6, FIG. 6 shows one stage of the method for manufacturing the memory device. A insulating film 121 and an insulating film 122A are formed. In an embodiment, the insulating film 121 and the insulating film 122A can be sequentially formed on the insulating material film 108 and the first pillar portions 130A. The insulating film 121 and the insulating film 122A may include insulating materials, such as silicon oxide, lithium titanium oxide (LTO), silicon nitride, hafnium oxide (HfO_x), zirconium hafnium oxide (HfZrO_x) or silicon oxynitride (SiON_x).

Referring to FIG. 7, FIG. 7 shows one stage of the method for manufacturing the memory device. An insulating film 122 is formed. In an embodiment, a portion of the insulating film 122A is removed through an etching process to expose a portion of the upper surface 121U of the insulating film 121, and the remained portion of the insulating film 122A is the insulating film 122.

Referring to FIG. 8, FIG. 8 shows one stage of the method for manufacturing the memory device. A conductive film 123 and an insulating film 124 are formed. In an embodiment, the conductive film 123 is formed on the upper surface 121U of the insulating film 121 and the sidewall 122S of the insulating film 122 through a deposition process, and then the insulating film 124 is formed on the insulating film 122 and the conductive film 123 through a deposition process. The conductive film 123 may include a conductive material, such as tungsten, titanium nitride, tantalum nitride, ruthenium, cobalt, nickel, aluminum, doped polycrystalline silicon, silicon germanium (SiGe_x), or carbon. Doped polycrystalline silicon may include N+ polycrystalline silicon and P+ polycrystalline silicon. In an embodiment, the conductive film 123 includes tungsten and titanium nitride. The insulating film 124 may include an insulating material, such as silicon oxide, lithium titanium oxide (LTO), silicon nitride, hafnium oxide (HfO_x), zirconium hafnium oxide (HfZrO_x) or silicon oxynitride (SiON_x).

Referring to FIG. 9, FIG. 9 shows one stage of the method for manufacturing the memory device. Holes 960 are formed. The holes 960 are arranged separately from each other in the conductive film 123. The hole 960 extends along the first direction D1 and passes through the insulating film 124, the conductive film 123 and the insulating film 121. The upper surfaces of the first pillar portions 130A, the sidewalls of the insulating film 121, the sidewalls of the conductive film 123 and the sidewalls of the insulating film 124 are exposed by the holes 960. The positions of the holes 960 can correspond to the positions of the first pillar portions 130A. In an embodiment, a portion of the insulating film 124, a portion of the conductive film 123 and a portion of the insulating film 121 are removed through an etching process to form the holes 960.

Referring to FIG. 10, FIG. 10 shows one stage of the method for manufacturing the memory device. Second pillar portions 130B are formed. In an embodiment, a gate dielectric can be filled in the holes 960 through a deposition process, and a portion of the gate dielectric can be removed through a anisotropic etching process to form a dielectric element 132. A channel element 133 is formed on the sidewall of the dielectric element 132 through a deposition process. A dielectric pillar 134 is formed on the sidewall of the channel element 133 through a deposition process. The dielectric pillar 134 may fills the space surrounded by the channel element 133. A pad 135 is formed on the upper surface of the dielectric element 132, the upper surface of the channel element 133 and the upper surface of the dielectric pillar 134 through a deposition process. Therefore, the second pillar portion 130B including the dielectric element 132, the channel element 133, the dielectric pillar 134 and the pad 135 are formed. The gate dielectric may include a dielectric material, such as silicon oxide, lithium titanium oxide (LTO), silicon nitride, hafnium oxide (HfO_x), zirconium hafnium oxide (HfZrO_x) or silicon oxynitride (SiON_x). The channel element 133 may include doped polycrystalline silicon or undoped polycrystalline silicon or indium gallium zinc oxide (IGZO). The dielectric pillar 134 may include oxide such as silicon oxide. The pad 135 may include a conductive material.

Referring to FIG. 11, FIG. 11 shows one stage of the method for manufacturing the memory device. An insulating film 125 is formed. In an embodiment, the insulating film 125 can be formed on the insulating film 124 and the second pillar portions 130B through a deposition process. The insulating film 125 may include an insulating material, such as silicon oxide, lithium titanium oxide (LTO), silicon nitride, hafnium oxide (HfO_x), zirconium hafnium oxide (HfZrO_x) or silicon oxynitride (SiON_x).

Referring to FIG. 12, FIG. 12 shows one stage of the method for manufacturing the memory device. Holes 1260 are formed. The holes 1260 are arranged separately from each other in the memory array stack 102A of the stack structure 102. The hole 1260 extends along the first direction D1 and passes through the insulating film 125, the insulating film 124, the insulating film 122, the insulating film 121, the insulating material film 108 and the memory array stack 102A. A portion of the upper surface 101U of the substrate 101, the sidewalls of the memory array stack 102A, the sidewalls of the insulating material film 108, the sidewalls of the insulating film 121, the sidewalls of the insulating film 122, the sidewalls of the insulating film 124 and the sidewalls of the insulating film 125 are exposed by the holes 1260. In an embodiment, a portion of the insulating film 125, a portion of the insulating film 124, a portion of the insulating film 122, a portion of the insulating film 121, a portion of the insulating material film 108 and a portion of the memory array stack 102A are removed through an etching process to form the holes 1260.

Referring to FIG. 13, FIG. 13 shows one stage of the method for manufacturing the memory device. Pillar structures 160 are formed. In an embodiment, a first electrode layer 164 is formed on the upper surface 101U of the substrate 101, the sidewall of the memory array stack 102A, the sidewall of the insulating material film 108, the sidewall of the insulating film 121, the sidewall of the insulating film 122, the sidewall of the insulating film 124 and the sidewall of the insulating film 125 exposed by the hole 1260 through a deposition process. An ovonic material layer 161 can be formed on the upper surface 101U of the substrate 101 exposed by the hole 1260 and the sidewall of the first electrode 164 through a deposition process. A second electrode layer 162 can be formed on the upper surface 101U of the substrate 101 exposed by the hole 1260 and the sidewall of the ovonic material layer 161 through a deposition process. A conductive pillar 163 can be formed on the upper surface 101U of the substrate 101 exposed by the hole 1260 and the sidewall of the second electrode layer 162 through a deposition process. A portion of the first electrode 164, a portion of the ovonic material layer 161, a portion of the second electrode 162, and a portion of the conductive pillar 163 can be removed through an etching process, and then a landing pad 168 can be formed on the remained portions of the first electrode 164, the ovonic material layer 161, the second electrode 162 and the conductive pillar 163 through a deposition process. Therefore, the pillar structure 160 including the first electrode layer 164, the ovonic material layer 161, the second electrode layer 162, the conductive pillar 163 and the landing pad 168 are formed. The conductive pillar 163 can fill the space surrounded by the second electrode layer 162.

The first electrode layer 164 and the second electrode layer 162 may include conductive materials, such as titanium nitride, tantalum nitride, titanium, cobalt, doped polycrystalline silicon and silicide. The first electrode layer 164 and the second electrode layer 162 may include the same or different materials. In some embodiments, the first electrode layer 164 and the second electrode layer 162 may each independently be a C/TiN multilayer structure or composite material, or tantalum nitride, or a Ti/TaN multilayer structure or composite material, or cobalt, or N+ polycrystalline silicon, or P+ polycrystalline silicon, or silicide. The ovonic material layer 161 may include chalcogenide. In some embodiments, the ovonic material layer 161 may be a Ge/As/Se multilayer structure or composite material, or a Ge/As/Se/Sn multilayer structure or composite material, or a Ge/As/Si/Se/Te/S multilayer structure or composite material, or a Ge/As/SiTe/S/Sn multilayer structure or composite material, or a Si/Te/As/Se/Si multilayer structure or composite material. The conductive pillar 163 may include a conductive material, such as titanium nitride, tantalum nitride, cobalt, tungsten, copper, ruthenium, aluminum, and silicide. In some embodiments, the conductive pillar 163 includes TiN/TaN multilayer structure or composite material. The landing pad 168 may include a conductive material such as titanium nitride, tantalum nitride, tungsten, copper, cobalt, aluminum, doped polycrystalline silicon and silicide. In some embodiments, the landing pad 168 includes or is a TiN/W/Cu multilayer structure or composite material.

In other embodiments, the pillar structure 160 may not include the first electrode layer 164 and/or the second electrode layer 162, and thus the steps of forming the first electrode layer 164 and/or the second electrode layer 162 described above can be omitted.

Referring to FIG. 14, FIG. 14 shows one stage of the method for manufacturing the memory device. An insulating film 126, holes 1460 and holes 1461 are formed. The insulating film 126 is on the insulating film 125 and the pillar structures 160. The holes 1460 are arranged separately from each other on the staircase stack 102B of the stack structure 102. The hole 1460 extends along the first direction D1 and passes through the insulating film 125 and the insulating film 126. The upper surfaces of the pads 135 of the second pillar portions 130B, the sidewalls of the insulating film 125 and the sidewalls of insulating film 126 are exposed by the holes 1460. The holes 1461 are arranged separately from each other on the memory array stack 102A of the stack structure 102. The hole 1461 extends along the first direction D1 and passes through the insulating film 126. The upper surfaces of the landing pads 168 of the pillar structures 160 and the sidewalls of the insulating film 126 are exposed by the holes 1461. In an embodiment, an insulating film 126 can be formed on the insulating film 125 and the pillar structures 160 through a deposition process, and then a portion of the insulating film 125 and a portion of the insulating film 126 can be removed through an etching process to form the holes 1460 and 1461. The insulating film 126 may include an insulating material, such as silicon oxide, lithium titanium oxide (LTO), silicon nitride, hafnium oxide (HfO_x), zirconium hafnium oxide (HfZrO_x) or silicon oxynitride (SiON_x).

Referring to FIG. 15, FIG. 15 shows one stage of the method for manufacturing the memory device. Contact pillars 151 and third pillar portions 130C are formed. In an embodiment, the third pillar portions 130C are formed in the holes 1460 through a deposition process and the contact pillars 151 are formed in the holes 1461 through a deposition process. The contact pillar 151 and the third pillar portion 130C may include conductive materials, such as doped or undoped polycrystalline silicon or metal.

Referring to FIG. 16, FIG. 16 shows one stage of the method for manufacturing the memory device. Wires 152 are formed. The wires can be formed on the upper surfaces of the contact pillars 151 and the upper surfaces of the third pillar portions 130C through a deposition process. The positions of the wires can correspond to the positions of the contact pillars 151 and the third pillar portions 130C. The wires 152 may include conductive materials.

In an embodiment, through the method schematically illustrated in FIGS. 2 to 16, a memory device 10 shown in FIGS. 1A and 1B is provided. In an embodiment, the method shown in FIGS. 2 to 16 use a high thermal process to form the second pillar portion 130B, so that a larger current can pass through the channel element 133 of the second pillar portion 130B.

FIGS. 17 to 31 illustrate a method for manufacturing a memory device according to another embodiment of the present disclosure.

Referring to FIG. 17, FIG. 17 shows one stage of the method for manufacturing the memory device. A substrate 101 is provided. Insulating material layers 1703 and insulating material layers 204 stacked alternately along the first direction D1 are formed on the upper surface 101U of the substrate 101. The first direction D1 may be the normal direction of the upper surface 101U of the substrate 101. In an embodiment, the insulating material layers 1703 and the insulating material layers 204 are formed on the upper surface 101U of the substrate 101 through a deposition process. The thickness of the lowest insulating material layer 204 among the insulating material layers 204 in the first direction D1 may be greater than the thickness of the other insulating material layer 204 in the first direction D1. The topmost insulating material layer 204 among the insulating material layers 204 may be a hard mask layer. The insulating material layer 1703 may include nitride such as silicon nitride.

Referring to FIG. 18, FIG. 18 shows one stage of the method for manufacturing the memory device. An insulating stack structure 1802 is formed on the substrate 101. In an embodiment the insulating material layers 1703 and the insulating material layers 204 shown in FIG. 17 are patterned through an etching process so as to form the insulating stack structure 1802 including an insulating stack 1802A and a staircase insulating stack 1802B. A portion of the insulating material layer 1703 defined in the insulating stack 1802A is an insulating layer 1703A. A portion of the insulating material layer 1703 defined in the staircase insulating stack 1802B is an insulating stair layer 1703B. A portion of the insulating material layer 204 defined in the insulating stack 1802A is an insulating layer 104. A portion of the insulating material layer 204 defined in the staircase insulating stack 1802B is an insulating stair layer 106. The insulating stack 1802A includes the insulating layers 1703A and the insulating layers 104 stacked alternately. The staircase insulating stack 1802B includes the insulating stair layers 1703B and the insulating stair layers 106 stacked alternately.

Referring to FIG. 19, FIG. 19 shows one stage of the method for manufacturing the memory device. An insulating material film 108 is formed on the insulating stack 1802A and the staircase insulating stack 1802B. In an embodiment, the insulating material film 108 is formed on the insulating stack 1802A and the staircase insulating stack 1802B through a deposition process.

Referring to FIG. 20, FIG. 20 shows one stage of the method for manufacturing the memory device. Holes 2060 are formed. The holes 2060 are arranged separately from each other in the insulating stack 1802A and the staircase insulating stack 1802B. The holes 2060 extend along the first direction D1 and pass through the insulating material film 108, the insulating stack 1802A and the staircase insulating stack 1802B. A portion of the upper surface 101U of the substrate 101, sidewalls of the insulating stack 1802A, sidewalls of the staircase insulating stack 1802B, and sidewalls of the insulating material film 108 are exposed by the holes 2060. In an embodiment, a portion of the insulating stack 1802A, a portion of the staircase insulating stack 1802B and a portion of the insulating material film 108 are removed by an etching process to form the holes 2060.

Referring to FIG. 21, FIG. 21 shows one stage of the method for manufacturing the memory device. Pillar structures 160 are formed. In an embodiment, a first electrode layer 164, an ovonic material layer 161, a second electrode layer 162, a conductive pillar 163 and a landing pad 168 can be sequentially formed in the hole 2060 through deposition processes and etching processes so as to form the pillar structure 160. In other embodiments, the pillar structure 160 may not include the first electrode layer 164 and/or the second electrode layer 162, and thus the steps of forming the first electrode layer 164 and/or the second electrode layer 162 described above can be omitted.

Referring to FIG. 22, FIG. 22 shows one stage of the method for manufacturing the memory device. The insulating layers 1703A and the insulating stair layers 1703B are removed to form recesses 2260. The pillar structures 160 can be used as support elements of the structure to avoid collapse. In an embodiment, the insulating layers 1703A between the insulating layers 104 and the insulating stair layers 1703B between the insulating stair layer 106 are removed through an etching process to form the recesses 2260 and remain the insulating layers 104 and the insulating stair layer 106.

Referring to FIG. 23, FIG. 23 shows one stage of the method for manufacturing the memory device. Conductive layers 103 and conductive stair layers 105 are formed. In an embodiment, the conductive layers 103 and the conductive stair layers 105 are formed in the recesses 2260 through a deposition process, and thus a stack structure 102 including a memory array stack 102A and a staircase stack 102B is formed.

Referring to FIG. 24, FIG. 24 shows one stage of the method for manufacturing the memory device. First pillar portions 130A are formed. In an embodiment, a portion of the staircase stack 102B and a portion of the insulating material film 108 are removed through an etching process to form holes 2460, and then conductive materials are filled in the holes 2460 to form the first pillar portions 130A. The holes 2460 are arranged separately from each other in the insulating material film 108. The sidewalls of the insulating material film 108 and the upper surfaces of the conductive stair layers 105 are exposed by the holes 2460. In an embodiment, a barrier film can be formed on the sidewall of the insulating material film 108