阅读说明：本技术 垂直型存储器件及其制备方法 (Vertical memory device and method of fabricating the same ) 是由 刘金营 于 2021-08-31 设计创作，主要内容包括：本发明提供一种垂直型存储器件及其制备方法。器件包括下逻辑单元及上逻辑单元,上逻辑单元位于下逻辑单元的上方,且与下逻辑单元接触；下逻辑单元包括基底及第一栅极结构层,基底内形成有第一源区、第一漏区及第一沟道区,第一沟道区位于第一源区和第一漏区之间,且均相邻接,第一栅极结构层位于第一沟道区的上表面；上逻辑单元包括第二源区、第二漏区、第二沟道区和第二栅极结构层,在第一栅极结构层上方依次堆叠,第二栅极结构层包括第二栅介质层及第二栅金属层,第二栅介质层绕设于第二沟道区的周向上,第二栅金属层绕设于第二栅介质层的周向上,上逻辑单元的漏极同时作为下逻辑单元的电容器。本发明可以降低动态电荷刷新时间。(The invention provides a vertical memory device and a method for manufacturing the same. The device comprises a lower logic unit and an upper logic unit, wherein the upper logic unit is positioned above the lower logic unit and is in contact with the lower logic unit; the lower logic unit comprises a substrate and a first grid structure layer, wherein a first source region, a first drain region and a first channel region are formed in the substrate, the first channel region is positioned between the first source region and the first drain region and is adjacent to each other, and the first grid structure layer is positioned on the upper surface of the first channel region; the upper logic unit comprises a second source region, a second drain region, a second channel region and a second grid structure layer, wherein the second source region, the second drain region, the second channel region and the second grid structure layer are sequentially stacked above the first grid structure layer, the second grid structure layer comprises a second grid dielectric layer and a second grid metal layer, the second grid dielectric layer is arranged in the circumferential direction of the second channel region in a winding mode, the second grid metal layer is arranged in the circumferential direction of the second grid dielectric layer in a winding mode, and the drain electrode of the upper logic unit is simultaneously used as a capacitor of the lower logic unit. The invention can reduce the dynamic charge refreshing time.)

1. A vertical memory device comprises a lower logic unit and an upper logic unit, wherein the upper logic unit is positioned above the lower logic unit and is contacted with the lower logic unit; the lower logic unit comprises a substrate and a first grid structure layer, wherein a first source region, a first drain region and a first channel region are formed in the substrate, the first channel region is positioned between the first source region and the first drain region and is adjacent to the first source region and the first drain region, and the first grid structure layer is positioned on the upper surface of the first channel region; the upper logic unit comprises a second source region, a second drain region, a second channel region and a second grid structure layer, wherein the second drain region, the second channel region and the second source region are sequentially stacked above the first grid structure layer, the second grid structure layer comprises a second grid dielectric layer and a second grid metal layer, the second grid dielectric layer is wound on the circumferential direction of the second channel region, the second grid metal layer is wound on the circumferential direction of the second grid dielectric layer, and the drain electrode of the upper logic unit is simultaneously used as the capacitor of the lower logic unit.

2. The vertical memory device of claim 1, further comprising a sidewall spacer structure located on the periphery of the first gate structure layer and the second drain region.

3. The vertical memory device of claim 1, wherein the first gate structure layer comprises a first gate oxide layer, a first high-K dielectric material layer and a first gate conductive material layer from bottom to top, the second gate dielectric layer comprises a second gate oxide layer and a second high-K dielectric material layer from inside to outside, the first high-K dielectric material layer and the second high-K dielectric material layer comprise one or two of HfO2 and ZrO2, the first gate conductive material layer comprises one or two of a polysilicon layer and an IGZO layer, and the second gate metal layer comprises a work function metal.

4. The vertical memory device of claim 1, wherein the upper logic cell comprises any one of an NNN-type, PPP-type, NPN-type, and PNP-type logic cell.

5. A method for fabricating a vertical type memory device, comprising the steps of:

providing a substrate, wherein a first source region, a first drain region and a first channel region are defined on the substrate, and the first channel region is positioned between the first source region and the first drain region and is adjacent to the first source region and the first drain region;

depositing a first grid material layer, a second drain material layer, a second channel material layer and a second source material layer on the substrate in sequence;

photoetching and etching the second source material layer, the second channel material layer, the second drain material layer and the first gate material layer to expose regions of the substrate corresponding to the first source region and the first drain region, and forming a first gate structure layer, a second drain region, a second channel region and a second source region which are sequentially and correspondingly positioned on the first channel region after etching;

forming a side wall protective layer, wherein the side wall protective layer covers the second source region, the second channel region, the second drain region and the first grid electrode structure layer and extends to the surface of the region corresponding to the first source region and the first drain region;

carrying out photoetching to expose areas corresponding to the first source area and the first drain area;

doping regions corresponding to the first source region and the first drain region to correspondingly form a first source region and a first drain region;

removing the side wall protective layers on the periphery of the second channel region and the second source region;

forming a second grid structure layer in the circumferential direction of the second channel region, wherein the second grid structure layer sequentially comprises a second grid dielectric layer and a second grid metal layer from inside to outside;

the first source region, the first drain region, the first channel region and the first grid structure layer form a lower logic unit, and the second source region, the second drain region, the second channel region and the second grid structure layer form an upper logic unit.

6. The preparation method of claim 5, wherein the first gate material layer comprises, from bottom to top, a first gate oxide layer, a first high-K dielectric material layer and a first gate conductive material layer; the second gate dielectric layer sequentially comprises a second gate oxide layer and a second high-K dielectric material layer from inside to outside, and the second gate metal layer comprises a work function metal layer.

7. The manufacturing method of claim 6, wherein the material of the first high-K dielectric material layer comprises one or both of HfO2 and ZrO2, the material of the first gate conductive material layer comprises one or both of a polysilicon layer and an IGZO layer, the method for forming the first gate oxide layer comprises a thermal oxidation method, the method for forming the first high-K dielectric material layer and the second gate dielectric layer comprises an atomic layer deposition method, and the method for forming the first gate conductive material layer comprises a vapor deposition method.

8. The method according to claim 5, wherein the second drain material layer and the second source material layer are made of one or two of silicon carbide and silicon, the second channel material layer is made of one of silicon, silicon germanium and germanium, and the method for forming the second drain material layer, the second source material layer and the second channel material layer comprises epitaxy.

9. The method according to claim 5, wherein the side wall protective layer comprises a first silicon oxide layer, a silicon nitride layer and a second silicon oxide layer in sequence from inside to outside, the method for forming the first silicon oxide layer and the silicon nitride layer comprises an atomic layer deposition method, and the method for forming the second silicon oxide layer comprises a sub-atmospheric pressure chemical vapor deposition method.

10. The method of claim 5, wherein the step of forming the second gate structure layer comprises: sequentially forming a second gate dielectric layer on the second channel region and the second source region in the circumferential direction;

removing the second gate dielectric layer positioned on the circumferential direction of the second source region;

and forming a second gate metal layer on the circumferential direction of the second gate dielectric layer which is remained on the circumferential direction of the second channel region.

Technical Field

The invention relates to the field of integrated circuits, in particular to a memory device, and particularly relates to a vertical memory device and a preparation method thereof.

Background

With the development of technology and the increasing living standard of people, higher and higher requirements are put forward on the aspects of miniaturization, multifunctionalization and energy consumption reduction of devices, which prompts technical personnel to make efforts from various aspects such as materials, processes and the like, thereby realizing the continuous reduction of the size of integrated circuit devices.

In the conventional structure of the dynamic random access memory, a metal or metal nitride electrode plate is generally adopted as a capacitor, the storage time of charges on the metal or metal nitride electrode plate is extremely short, high frequency is required for charging the capacitor, higher energy consumption is caused, and the dynamic random access memory with a novel structure is required to be introduced to reduce the energy consumption.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a vertical type memory device and a method for manufacturing the same, which are used to solve the problems of power consumption increase and the like caused by frequent charging of the memory device in the prior art. The invention adopts a mode that the upper logic unit charges the lower logic unit, and one or two of the polysilicon layer and the IGZO layer are used for replacing a metal or metal nitride electrode plate to serve as a capacitor, so that the disappearance frequency of charges in the capacitor can be effectively reduced, and the energy consumption of the storage device is reduced.

To achieve the above and other related objects, the present invention provides a vertical type memory device including a lower logic cell and an upper logic cell, the upper logic cell being located above the lower logic cell and contacting the lower logic cell; the lower logic unit comprises a substrate and a first grid structure layer, wherein a first source region, a first drain region and a first channel region are formed in the substrate, the first channel region is positioned between the first source region and the first drain region and is adjacent to the first source region and the first drain region, and the first grid structure layer is positioned on the upper surface of the first channel region; the upper logic unit comprises a second source region, a second drain region, a second channel region and a second grid structure layer, wherein the second drain region, the second channel region and the second source region are sequentially stacked above the first grid structure layer, the second grid structure layer comprises a second grid dielectric layer and a second grid metal layer, the second grid dielectric layer is wound on the circumferential direction of the second channel region, the second grid metal layer is wound on the circumferential direction of the second grid dielectric layer, and the drain electrode of the upper logic unit is simultaneously used as the capacitor of the lower logic unit.

Optionally, the vertical memory device further includes a sidewall structure located on the first gate structure layer and the second drain region.

Optionally, the first gate structure layer sequentially includes, from bottom to top, a first gate oxide layer, a first high-K dielectric material layer, and a first gate conductive material layer.

Optionally, the second gate dielectric layer sequentially includes a second gate oxide layer and a second high-K dielectric material layer from inside to outside.

Optionally, the first high-K dielectric material layer and the second high-K dielectric material layer include one or both of HfO2 and ZrO 2.

Optionally, the first gate conductive material layer includes one or both of a polysilicon layer and an IGZO layer.

Optionally, the second gate metal layer comprises a workfunction metal.

Optionally, the upper logic unit includes any one of NNN type, PPP type, NPN type, and PNP type logic units.

The invention also provides a preparation method of the vertical memory device, which comprises the following steps:

providing a substrate, wherein a first source region, a first drain region and a first channel region are defined on the substrate, and the first channel region is positioned between the first source region and the first drain region and is adjacent to the first source region and the first drain region;

depositing a first grid material layer, a second drain material layer, a second channel material layer and a second source material layer on the substrate in sequence;

photoetching and etching the second source material layer, the second channel material layer, the second drain material layer and the first gate material layer to expose regions of the substrate corresponding to the first source region and the first drain region, and forming a first gate structure layer, a second drain region, a second channel region and a second source region which are sequentially and correspondingly positioned on the first channel region after etching;

forming a side wall protective layer, wherein the side wall protective layer covers the second source region, the second channel region, the second drain region and the first grid electrode structure layer and extends to the surface of the region corresponding to the first source region and the first drain region;

carrying out photoetching to expose areas corresponding to the first source area and the first drain area;

doping regions corresponding to the first source region and the first drain region to correspondingly form a first source region and a first drain region;

removing the side wall protective layers on the periphery of the second channel region and the second source region;

forming a second gate structure layer on the second channel region, wherein the second gate structure layer sequentially comprises a second gate dielectric layer and a second gate metal layer from inside to outside,

the first source region, the first drain region, the first channel region and the first grid structure layer form a lower logic unit, and the second source region, the second drain region, the second channel region and the second grid structure layer form an upper logic unit.

Optionally, the first gate material layer sequentially includes, from bottom to top, a first gate oxide layer, a first high-K dielectric material layer, and a first gate conductive material layer.

Optionally, the material of the first high-K dielectric material layer includes one or both of HfO2 and ZrO 2.

Optionally, the material of the first gate conductive material layer includes one or both of a polysilicon layer and an IGZO layer.

More optionally, the method for forming the first gate oxide layer comprises a thermal oxidation method.

Optionally, the method of forming the first high-K dielectric material layer includes an atomic layer deposition method.

Optionally, the method of forming the first gate conductive material layer includes a vapor deposition method.

Optionally, the second drain material layer and the second source material layer are made of one or two of silicon carbide and silicon.

Optionally, a material of the second channel material layer includes one of silicon, silicon germanium and germanium.

Optionally, the method for forming the second drain material layer, the second source material layer and the second channel material layer includes an epitaxial method.

Optionally, the side wall protection layer sequentially includes a first silicon oxide layer, a silicon nitride layer and a second silicon oxide layer from inside to outside, the method for forming the first silicon oxide layer and the silicon nitride layer includes an atomic layer deposition method, and the method for forming the second silicon oxide layer includes a sub-atmospheric pressure chemical vapor deposition method.

Optionally, the second gate dielectric layer sequentially includes a second gate oxide layer and a second high-K dielectric material layer from inside to outside.

Optionally, the method for forming the second gate dielectric layer includes an atomic layer deposition method.

Optionally, the second gate metal layer comprises a workfunction metal layer.

Optionally, the method for forming the second gate structure layer includes:

sequentially forming a second gate dielectric layer on the second channel region and the second source region in the circumferential direction;

removing the second gate dielectric layer positioned on the circumferential direction of the second source region;

and forming a second gate metal layer on the circumferential direction of the second gate dielectric layer which is remained on the circumferential direction of the second channel region.

As described above, the vertical memory device and the method for manufacturing the same according to the present invention have the following advantageous effects: the invention designs a brand-new vertical cylindrical 2T0C storage structure, can realize charge storage without independently manufacturing a capacitor, is beneficial to further reducing the size of a device while ensuring the storage capacity of the device, and reduces the cost and the energy consumption of the device.

Drawings

Fig. 1 is a schematic cross-sectional view of a vertical memory device according to the present invention.

Fig. 2-17 are schematic cross-sectional views of a vertical memory device according to the present invention during fabrication.

Description of the element reference numerals

Logic unit under 1

10 base

11 first source region

12 first drain region

13 first channel region

14 first gate structure layer

141 first gate oxide layer

142 first high-K dielectric material layer

143 first gate conductive material layer

2 logic unit

21 second source region

21a second source material layer

22 second drain region

22a second layer of drain material

23 second channel region

23a second channel material layer

24 second gate structure layer

241 second gate dielectric layer

241a second gate oxide layer

241b second high-K dielectric material layer

242 second gate metal layer

3 side wall structure

3a first silicon oxide layer

3b silicon nitride layer

3c second silicon oxide layer

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated. In order to keep the drawings as concise as possible, not all features of a single figure may be labeled in their entirety.

In a conventional dynamic random access memory, a metal or metal nitride electrode plate is generally used as a capacitor, the storage time of charges on the metal or metal nitride electrode plate is extremely short, high frequency is required to charge the capacitor, so that the capacitor has higher energy consumption, and a dynamic memory with a novel structure is required to be introduced to reduce the energy consumption. In view of the above, the inventors of the present application have made a long-term study and have proposed an improvement.

Specifically, as shown in fig. 1, the present invention provides a vertical type memory device, which includes a lower logic unit 1 and an upper logic unit 2, wherein the upper logic unit 2 is located above the lower logic unit 1 and is in contact with the lower logic unit 1; the lower logic unit 1 comprises a substrate 10 and a first gate structure layer 14, wherein a first source region 11, a first drain region 12 and a first channel region 13 are formed in the substrate 10, the first channel region 13 is located between the first source region 11 and the first drain region 12 and is adjacent to both the first source region 11 and the first drain region 12, and the first gate structure layer 14 is located on the upper surface of the first channel region 13 (that is, the upper logic unit 2 is a planar gate structure); the upper logic unit 2 includes a second source region 21, a second drain region 22, a second channel region 23, and a second gate structure layer 24, where the second drain region 22, the second channel region 23, and the second source region 21 are sequentially stacked above the first gate structure layer 14, the second gate structure layer 24 includes a second gate dielectric layer 241 and a second gate metal layer 242, the second gate dielectric layer 241 is wound around the second channel region 23 in the circumferential direction, and the second gate metal layer 242 is wound around the second gate dielectric layer 241 in the circumferential direction (that is, the upper logic unit 2 is a ring gate structure, or a GAA structure); the second drain region 22 of the upper logic cell 2 is connected to the first gate structure layer 14 of the lower logic cell 1, so that it can control the switch of the lower logic cell 1, and the second drain region 22 of the upper logic cell 2 serves as a capacitor of the lower logic cell 1, so that signals can be read through the lower logic cell 1. The invention designs a brand-new vertical cylindrical 2T0C storage structure, and can realize charge storage without independently manufacturing a capacitor. According to the invention, one or two of the polysilicon layer and the IGZO layer are adopted to replace metal or metal nitride electrode plates to serve as capacitors, so that the disappearance frequency of charges in the capacitors can be effectively reduced, and the energy consumption of the storage device is reduced.

The upper logic unit 2 includes any one of NNN type, PPP type, NPN type, and PNP type logic units, as an example. The lower logic unit 1 may also be any one of NNN type, PPP type, NPN type, and PNP type logic units, and thus the type of the substrate 10 and the doping types of the source/drain regions and the channel regions of each logic unit may be selected according to the needs, and are not particularly limited. For example, in an example, the substrate 10 may be a P-type doped silicon substrate 10, the first source region 11 and the first drain region 12 in the substrate 10 are doped N-type, and the substrate 10 between the first source region 11 and the first drain region 12 serves as the first channel region 13.

In an example, the second source region 21 and the second drain region 22 of the upper logic unit 2 are made of silicon nitride, the second channel region 23 is made of silicon, and the material layers of the second source region 21, the second drain region 22 and the second channel region 23 may be formed by an epitaxial process.

In an example, the vertical memory device further includes a sidewall structure located in the circumferential direction of the first gate structure layer 14 and the second drain region 22, and the sidewall structure sequentially includes a first silicon oxide layer 3a, a silicon nitride layer 3b, and a second silicon oxide layer 3c from inside to outside (i.e., in a direction away from the center of the device). In an example, a surface of the second silicon oxide layer 3c located at the outermost side, which is away from the silicon nitride layer 3b, is a slope surface, so that the cross section of the sidewall structure is a trapezoidal structure with a narrow top and a wide bottom, which is beneficial to improving the stability of the sidewall structure, and the sidewall structure may extend to partial surfaces of the first source region 11 and the first drain region 12.

As an example, the first gate structure layer 14 includes, from bottom to top, a first gate oxide layer 141, a first high-K dielectric material layer 142, and a first gate conductive material layer 143, that is, the second drain region 22 of the upper logic unit 2 is in contact connection with the first gate conductive material layer 143. In a further example, the first high-K dielectric material layer 142 includes, but is not limited to, one or both of HfO2 and ZrO2, and the first gate conductive material layer 143 includes one or both of a polysilicon layer and an IGZO (indium gallium zinc oxide) layer.

As an example, the second gate dielectric layer 241 includes a second gate oxide layer 241a and a second high-K dielectric material layer 241b, and the second high-K dielectric material layer 241b also preferably includes but is not limited to one or both of HfO2 and ZrO 2.

By way of example, the second gate metal layer 242 includes a workfunction metal, including but not limited to a combination of one or more of Ti, TiN, Ta, and TaN.

The invention also provides a preparation method of the vertical type memory device in any one of the above schemes, or the vertical type memory device in any one of the above schemes can be prepared based on the preparation method. The preparation method comprises the following steps:

providing a substrate 10, wherein a first source region 11, a first drain region 12 and a first channel region 13 are defined on the substrate 10, the first channel region 13 is located between the first source region 11 and the first drain region 12, and is adjacent to both the first source region 11 and the first drain region 12 (please understand in conjunction with fig. 1 and fig. 2), and in this example, the substrate 10 is a P-type doped substrate;

sequentially depositing a first gate material layer, a second drain material layer 22a, a second channel material layer 23a and a second source material layer 21a on the substrate 10; in an example, the first gate material layer sequentially comprises a first gate oxide layer 141, a first high-K dielectric material layer 142 and a first gate conductive material layer 143 from bottom to top, and a method for forming the first gate oxide layer 141 is preferably, but not limited to, a thermal oxidation method; the first high-K dielectric material layer 142 includes, but is not limited to, one or both of HfO2 and ZrO2, and the method of forming the first high-K dielectric material layer 142 is preferably, but not limited to, an atomic layer deposition method; the material of the first gate conductive material layer 143 includes, but is not limited to, one or both of a polysilicon layer and an IGZO layer, and the forming method is preferably, but not limited to, a vapor deposition method; the process of forming the first gate material layer is specifically shown in fig. 3-5; the material of the second drain material layer 22a is preferably, but not limited to, one or a combination of two of silicon carbide and silicon, the material of the second channel material layer 23a is preferably, but not limited to, any one of silicon, germanium and silicon germanium, the material of the second source material layer 21a is preferably, but not limited to, one or a combination of two of silicon carbide and silicon, and the second drain material layer 22a, the second channel material layer 23a and the second source material layer 21a are all preferably formed by an epitaxial process, so that they can be deposited continuously in the same apparatus without substrate 10 transfer, which helps to improve production efficiency and yield, and the manufacturing process can be illustrated with reference to fig. 6-8;

depositing a second source material layer 21a, a second channel material layer 23a, a second drain material layer 22a and a first gate material layerPerforming photoetching to expose the areas of the substrate 10 corresponding to the first source region 11 and the first drain region 12, and forming a first gate structure layer 14, a second drain region 22, a second channel region 23 and a second source region 21 which are sequentially and correspondingly positioned on the first channel region 13 after etching; first, a photoresist is coated and exposed to define the first source region 11 and the first drain region 12, and then, etching is performed by, but not limited to, dry etching, such as SF₆Or Cl₂Or performing one-step etching on the HBR and the oxygen to obtain a structure as shown in FIG. 9;

forming a side wall protective layer, wherein the side wall protective layer covers the second source region 21, the second channel region 23, the second drain region 22 and the first gate structure layer 14, and extends to the surface of the region corresponding to the first source region 11 and the first drain region 12; specifically, the forming process of the side wall protective layer may be that, first, a first silicon oxide layer 3a and a silicon nitride layer 3b are sequentially formed by using an atomic layer deposition process, the obtained structure is as shown in fig. 10, and then, a second silicon oxide layer 3c is formed by using a sub-atmospheric pressure chemical vapor deposition process, the obtained structure is as shown in fig. 11, that is, the two silicon oxide layers of the side wall protective layer are formed by different processes; the first silicon oxide layer 3a is formed by adopting an atomic layer deposition process, so that good contact with structures adjacent to the second channel region 23 and the like can be ensured without falling off, the oxide layer has good quality, the silicon oxide layers at all positions keep relatively the same thickness, and the second silicon oxide layer 3c is formed by adopting a sub-atmospheric pressure chemical vapor process, so that the production efficiency can be improved;

performing photolithography etching to expose regions corresponding to the first source region 11 and the first drain region 12, for example, performing dry etching, but removing the sidewall protection layer correspondingly located above the first source region 11 and the first drain region 12 by etching in multiple steps, and obtaining a structure as shown in fig. 12;

doping regions corresponding to the first source region 11 and the first drain region 12 by using an ion implantation method, wherein the doping type is determined according to the type of a device to be formed, and is not particularly limited, and high-temperature annealing and well pushing can be performed after doping, so that the obtained structure is as shown in fig. 13;

removing the sidewall protection layers at the peripheries of the second channel region 23 and the second source region 21 and only remaining the sidewall protection layers at the peripheries of the first gate structure layer 14 and the second drain region 22 to obtain the sidewall structure, wherein a dry etching method is preferably adopted in the step to avoid corrosion to the first source region 11 and the first drain region 12, and the structure obtained after the step is shown in fig. 14;

forming a second gate structure layer 24 in the circumferential direction of the second channel region 23, wherein the second gate structure layer 24 sequentially includes a second gate dielectric layer 241 and a second gate metal layer 242 from inside to outside; specifically, the step may include: preferably, but not limited to, an atomic layer deposition method is adopted to sequentially form a second gate dielectric layer 241 on the second channel region 23 and the second source region 21 in the circumferential direction, the second gate dielectric layer 241 preferably sequentially includes a second gate oxide layer 241a and a second high-K dielectric material layer 241b from inside to outside, the second gate oxide layer 241a and the first silicon oxide layer 3a of the sidewall structure are combined in the longitudinal direction to present a similar integral shape, the structure obtained after the step is shown in fig. 15 and 16, and the second high-K dielectric material layer 241b preferably includes one or both of HfO2 and ZrO 2;

removing the second gate dielectric layer 241 located on the circumferential direction of the second source region 21, and obtaining a structure as shown in fig. 17;

forming a second gate metal layer 242 in a circumferential direction of the second gate dielectric layer 241 remaining in a circumferential direction of the second channel region 23, for example, forming a support layer including a nitride material on a surface of a region below the second channel region 23, forming a second gate metal layer 242 on the support layer, removing the metal material in the circumferential direction of the second source region 21 while leaving only the metal material layer in the circumferential direction of the second channel region 23, and finally removing the support layer, wherein the second gate metal layer 242 preferably includes a work function metal layer, and the method for forming the second gate metal layer 242 includes, but is not limited to, a sputtering method; the first source region 11, the first drain region 12, the first channel region 13 and the first gate structure layer 14 form a lower logic unit 1, and the second source region 21, the second drain region 22, the second channel region 23 and the second gate structure layer 24 form an upper logic unit 2, so as to obtain the vertical memory device shown in fig. 1.

Of course, in other examples, after the second gate dielectric layer 241 and the second gate metal layer 242 are sequentially formed in the circumferential direction of the second channel region 23 and the second source region 21, the second gate dielectric layer 241 and the second gate metal layer 242 in the circumferential direction of the second source region 21 may be removed, and only the second gate dielectric layer 241 and the second gate metal layer 242 in the circumferential direction of the second channel region 23 may be remained. In another example, the lower logic unit 1 may be further prepared, for example, the first gate structure layer 14 is formed on the substrate 10, then the first source region 11 and the first drain region 12 are prepared in the substrate 10 by using an ion implantation and a high temperature drive-in process, then a protective material layer is formed on the surfaces of the first source region 11 and the first drain region 12, then the second drain material layer 22a, the second channel material layer 23a, and the second source material layer 21a are sequentially formed and etched to form the second drain region 22, the second channel region 23, and the second source region 21 from bottom to top, then the second gate structure layer 24 is formed in the circumferential direction of the second channel region 23, and finally the vertical memory device is obtained.

In summary, the present invention provides a vertical memory device and a method for fabricating the same. The vertical memory device comprises a lower logic unit and an upper logic unit, wherein the upper logic unit is positioned above the lower logic unit and is contacted with the lower logic unit; the lower logic unit comprises a substrate and a first grid structure layer, wherein a first source region, a first drain region and a first channel region are formed in the substrate, the first channel region is positioned between the first source region and the first drain region and is adjacent to the first source region and the first drain region, and the first grid structure layer is positioned on the upper surface of the first channel region; the upper logic unit comprises a second source region, a second drain region, a second channel region and a second grid structure layer, wherein the second drain region, the second channel region and the second source region are sequentially stacked above the first grid structure layer, the second grid structure layer comprises a second grid dielectric layer and a second grid metal layer, the second grid dielectric layer is wound on the circumferential direction of the second channel region, the second grid metal layer is wound on the circumferential direction of the second grid dielectric layer, and the drain electrode of the upper logic unit is simultaneously used as the capacitor of the lower logic unit. The invention designs a brand-new vertical cylindrical 2T0C storage structure, and can realize charge storage without independently manufacturing a capacitor. One or two of the polysilicon layer and the IGZO layer are adopted to replace metal or metal nitride electrode plates to serve as capacitors, so that the disappearance frequency of charges in the capacitors can be effectively reduced, and the energy consumption of the storage device is reduced. The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.