阅读说明：本技术 动态随机存取存储器及其形成方法 (Dynamic random access memory and forming method thereof ) 是由 华文宇 余兴 于 2021-04-07 设计创作，主要内容包括：一种动态随机存取存储器及其形成方法,包括：衬底,衬底第一面和第二面,衬底包括若干有源区,各有源区均包括隔离区、沟道区和字线区；位于隔离区内的第一隔离层；位于字线区内的字线栅结构；位于沟道区第一面内的第一源漏掺杂区；位于第一面上的位线层；位于沟道区第二面内的第二源漏掺杂区；位于第二面上的若干电容结构。通过将位线层和电容结构排布在衬底的第一面和第二面上,能够有效降低电路布线以及制造工艺的难度。将电容结构排布在衬底的第二面,使得电容结构具有更大的结构空间,进而使得电容结构的存储容量增加。将位线层和电容结构排布在衬底的第一面和第二面上,还能够有效减小单个存储结构占用的面积,能够提升存储器的存储密度。(A dynamic random access memory and a forming method thereof are disclosed, which comprises the following steps: the semiconductor device comprises a substrate, a first surface and a second surface of the substrate, wherein the substrate comprises a plurality of active regions, and each active region comprises an isolation region, a channel region and a word line region; a first isolation layer located within the isolation region; a word line gate structure located in the word line region; the first source-drain doped region is positioned in the first surface of the channel region; a bit line layer on the first side; the second source-drain doped region is positioned in the second surface of the channel region; a plurality of capacitor structures located on the second face. The difficulty of circuit wiring and a manufacturing process can be effectively reduced by arranging the bit line layer and the capacitor structure on the first surface and the second surface of the substrate. The capacitor structure is arranged on the second surface of the substrate, so that the capacitor structure has larger structural space, and the storage capacity of the capacitor structure is increased. The bit line layer and the capacitor structure are arranged on the first surface and the second surface of the substrate, so that the area occupied by a single storage structure can be effectively reduced, and the storage density of the memory can be improved.)

1. A dynamic random access memory, comprising:

the substrate is provided with a first surface and a second surface which are opposite, the substrate comprises a plurality of active regions which are mutually separated and parallel to a first direction, the active regions are arranged along a second direction, the first direction is vertical to the second direction, each active region comprises a plurality of isolation regions, a plurality of channel regions and a plurality of word line regions, the isolation regions and the channel regions in each active region are arranged at intervals along the first direction, and the word line regions are positioned between the adjacent isolation regions and the channel regions;

a word line gate structure located within the word line region, the word line gate structure extending from a first face to a second face, and the word line gate structure penetrating the active region along the second direction;

the first source-drain doped region is positioned in the first surface of the channel region;

a plurality of bit line layers parallel to the first direction and positioned on the first surface, wherein each bit line layer is electrically connected with a plurality of first source-drain doped regions in one active region;

the second source-drain doped region is positioned in the second surface of the channel region;

a first isolation layer located in the isolation region, the first isolation layer penetrating the substrate from the first side to the second side;

a second isolation layer located within the channel region, the second isolation layer extending from the second face in a direction toward the first face;

and each capacitor structure is electrically connected with one second source-drain doped region.

2. The dynamic random access memory of claim 1, further comprising: and the isolation structures are positioned between the adjacent active regions and penetrate through the substrate from the direction from the first surface to the second surface.

3. The dynamic random access memory of claim 1 wherein the word line region has a word line gate trench extending from the first face to the second face, the word line gate trench intersecting the active region in both directions; the word line gate structure comprises a word line gate dielectric layer positioned on the side wall and the bottom surface of the word line gate groove and a word line gate layer positioned on the word line gate dielectric layer.

4. The dynamic random access memory of claim 3, wherein the word line gate layer comprises a single layer structure or a composite structure.

5. The dynamic random access memory according to claim 4, wherein when the word line gate layer has a single-layer structure, a material of the word line gate layer includes a metal or polysilicon.

6. The dynamic random access memory of claim 5, wherein a height of the second spacer layer from the second side in the direction of the first side is greater than half a height of the word line gate layer from the second side in the direction of the first side.

7. The dynamic random access memory according to claim 4, wherein when the word line gate layer is a composite structure, the word line gate layer comprises a first gate layer and a second gate layer located on the first gate layer, and the first gate layer and the second gate layer are made of different materials.

8. The dynamic random access memory of claim 7, wherein the material of the first gate layer comprises a metal or polysilicon; the material of the second gate layer comprises polysilicon or metal.

9. The dynamic random access memory according to claim 8, wherein when the material of the first gate layer is polysilicon, a height of the second isolation layer from the second surface toward the first surface is greater than a height of the first gate layer from the second surface toward the first surface; when the material of the second gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the second gate layer from the second surface to the first surface.

10. The dynamic random access memory of claim 1, further comprising: and each bit line layer is electrically connected with a plurality of first conductive plugs on one active region.

11. The dynamic random access memory of claim 1, further comprising: and each capacitor structure is electrically connected with one second conductive plug.

12. The dynamic random access memory of claim 1, wherein the capacitive structure comprises: the electrode structure comprises a first electrode layer, a second electrode layer and a dielectric layer positioned between the first electrode layer and the second electrode layer.

13. The dynamic random access memory according to claim 1, wherein a projection of the capacitive structure from the second face in the direction of the first face partially overlaps a projection of the word line gate structure from the second face in the direction of the first face.

14. A method for forming a dynamic random access memory, comprising:

providing a substrate, wherein the substrate is provided with a first surface and a second surface which are opposite, the substrate comprises a plurality of active regions which are separated from each other and parallel to a first direction, the active regions are arranged along a second direction, the first direction is vertical to the second direction, each active region comprises a plurality of isolation regions, a plurality of channel regions and a plurality of word line regions, the isolation regions and the channel regions in each active region are arranged at intervals along the first direction, and the word line regions are positioned between the adjacent isolation regions and the channel regions;

forming a plurality of word line grid grooves in the word line area, wherein the word line grid grooves extend from the first surface to the second surface and penetrate through the active area along the two directions;

forming a word line gate structure in the word line gate groove;

forming a first source drain doped region in the first surface;

forming a plurality of bit line layers parallel to the first direction on the first surface, wherein each bit line layer is electrically connected with first source drain doped regions of a plurality of channel regions in one active region;

forming a second source drain doped region in each second surface;

thinning the substrate from the second surface to the first surface;

etching the isolation region from the second surface to the first surface, and forming a plurality of first isolation openings parallel to the second direction in the substrate;

forming a first isolation layer in the first isolation opening;

etching part of the channel region from the second surface to the first surface, and forming a second isolation opening in the channel region;

forming a second isolation layer in the second isolation opening;

and forming a plurality of capacitor structures on the second surface, wherein each capacitor structure is electrically connected with one second source drain doped region.

15. The method of forming a dynamic random access memory of claim 14, further comprising: and forming an isolation structure between adjacent active regions.

16. The method of claim 15, wherein the isolation structure comprises: forming a first isolation material layer between adjacent active regions and on the first face; and carrying out planarization treatment on the first isolation material layer until the first surface is exposed, and forming the isolation structure.

17. The method of claim 14, wherein the word line gate structure comprises: the word line gate structure comprises a word line gate dielectric layer positioned on the side wall and the bottom surface of a word line gate groove and a word line gate layer positioned on the word line gate dielectric layer.

18. The method of claim 17, wherein the word line gate layer comprises a single layer structure or a composite structure.

19. The method of claim 18, wherein when the word line gate layer is a single layer structure, the material of the word line gate layer comprises metal or polysilicon.

20. The method of claim 19, wherein a height of the second spacer layer from the second side toward the first side is greater than half a height of the word line gate layer from the second side toward the first side.

21. The method according to claim 18, wherein when the wordline gate layer is a composite structure, the wordline gate layer comprises a first gate layer and a second gate layer located on the first gate layer, and the first gate layer and the second gate layer are made of different materials.

22. The method of claim 20, wherein the material of the first gate layer comprises a metal or polysilicon; the material of the second gate layer comprises polysilicon or metal.

23. The method according to claim 22, wherein when the material of the first gate layer is polysilicon, a height of the second isolation layer from the second surface toward the first surface is greater than a height of the first gate layer from the second surface toward the first surface; when the material of the second gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the second gate layer from the second surface to the first surface.

24. The method of forming a dynamic random access memory of claim 14, further comprising, prior to forming a plurality of the bit line layers: and forming first conductive plugs on the first source-drain doped region of each channel region, wherein each bit line layer is electrically connected with a plurality of first conductive plugs on one active region.

25. The method of forming a dynamic random access memory of claim 14, further comprising, prior to forming the plurality of capacitor structures: and forming a second conductive plug on each second source-drain doped region, wherein each capacitor structure is electrically connected with one second conductive plug.

26. The method of claim 14, wherein the capacitor structure comprises: the electrode structure comprises a first electrode layer, a second electrode layer and a dielectric layer positioned between the first electrode layer and the second electrode layer.

27. The method of claim 14, wherein a projection of the capacitor structure from the second surface toward the first surface partially overlaps a projection of the word line gate structure from the second surface toward the first surface.

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a dynamic random access memory and a forming method thereof.

Background

With the rapid development of technology, semiconductor memories are widely used in electronic devices. Dynamic Random Access Memory (DRAM), which is a volatile memory, is the most commonly utilized solution for applications that store large amounts of data.

Generally, a dram is composed of a plurality of memory cells, each of which is mainly composed of a transistor and a capacitor operated by the transistor, and each of the memory cells is electrically connected to each other through a word line and a bit line.

However, the conventional dynamic random access memory still has many problems.

Disclosure of Invention

The invention provides a dynamic random access memory and a forming method thereof, which can effectively reduce the process difficulty and improve the storage capacity of a capacitor structure of the memory and the storage density of the memory.

To solve the above problems, the present invention provides a dynamic random access memory, comprising: the substrate is provided with a first surface and a second surface which are opposite, the substrate comprises a plurality of active regions which are mutually separated and parallel to a first direction, the active regions are arranged along a second direction, the first direction is vertical to the second direction, each active region comprises a plurality of isolation regions, a plurality of channel regions and a plurality of word line regions, the isolation regions and the channel regions in each active region are arranged at intervals along the first direction, and the word line regions are positioned between the adjacent isolation regions and the channel regions; a word line gate structure located within the word line region, the word line gate structure extending from a first face to a second face, and the word line gate structure penetrating the active region along the second direction; the first source-drain doped region is positioned in the first surface of the channel region; a plurality of bit line layers parallel to the first direction and positioned on the first surface, wherein each bit line layer is electrically connected with a plurality of first source-drain doped regions in one active region; the second source-drain doped region is positioned in the second surface of the channel region; a first isolation layer located in the isolation region, the first isolation layer penetrating the substrate from the first side to the second side; a second isolation layer located within the channel region, the second isolation layer extending from the second face in a direction toward the first face; and each capacitor structure is electrically connected with one second source-drain doped region.

Optionally, the method further includes: and the isolation structures are positioned between the adjacent active regions and penetrate through the substrate from the direction from the first surface to the second surface.

Optionally, the word line region has a word line gate trench, the word line gate trench extends from the first surface to the second surface, and the word line gate trench penetrates through the active region along the two directions; the word line gate structure comprises a word line gate dielectric layer positioned on the side wall and the bottom surface of the word line gate groove and a word line gate layer positioned on the word line gate dielectric layer.

Optionally, the word line gate layer includes a single layer structure or a composite structure.

Optionally, when the word line gate layer is of a single-layer structure, the material of the word line gate layer includes metal or polysilicon.

Optionally, the height of the second isolation layer from the second surface to the first surface is greater than half of the height of the word line gate layer from the second surface to the first surface.

Optionally, when the word line gate layer is of a composite structure, the word line gate layer includes a first gate layer and a second gate layer located on the first gate layer, and the first gate layer and the second gate layer are made of different materials.

Optionally, the material of the first gate layer includes metal or polysilicon; the material of the second gate layer comprises polysilicon or metal.

Optionally, when the material of the first gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the first gate layer from the second surface to the first surface; when the material of the second gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the second gate layer from the second surface to the first surface.

Optionally, the method further includes: and each bit line layer is electrically connected with a plurality of first conductive plugs on one active region.

Optionally, the method further includes: and each capacitor structure is electrically connected with one second conductive plug.

Optionally, the capacitor structure includes: the electrode structure comprises a first electrode layer, a second electrode layer and a dielectric layer positioned between the first electrode layer and the second electrode layer.

Optionally, a projection of the capacitor structure from the second surface to the first surface partially overlaps with a projection of the word line gate structure from the second surface to the first surface.

Correspondingly, the invention also provides a method for forming the dynamic random access memory, which comprises the following steps: providing a substrate, wherein the substrate is provided with a first surface and a second surface which are opposite, the substrate comprises a plurality of active regions which are separated from each other and parallel to a first direction, the active regions are arranged along a second direction, the first direction is vertical to the second direction, each active region comprises a plurality of isolation regions, a plurality of channel regions and a plurality of word line regions, the isolation regions and the channel regions in each active region are arranged at intervals along the first direction, and the word line regions are positioned between the adjacent isolation regions and the channel regions; forming a plurality of word line grid grooves in the word line area, wherein the word line grid grooves extend from the first surface to the second surface and penetrate through the active area along the two directions; forming a word line gate structure in the word line gate groove; forming a first source drain doped region in the first surface; forming a plurality of bit line layers parallel to the first direction on the first surface, wherein each bit line layer is electrically connected with first source drain doped regions of a plurality of channel regions in one active region; forming a second source drain doped region in each second surface; thinning the substrate from the second surface to the first surface until the surface of the first isolation layer is exposed; etching the isolation region from the second surface to the first surface, and forming a plurality of first isolation openings parallel to the second direction in the substrate; forming a first isolation layer in the first isolation opening; etching part of the channel region from the second surface to the first surface, and forming a second isolation opening in the channel region; forming a second isolation layer in the second isolation opening; and forming a plurality of capacitor structures on the second surface, wherein each capacitor structure is electrically connected with one second source drain doped region.

Optionally, the method further includes: and forming an isolation structure between adjacent active regions.

Optionally, the method for forming the isolation structure includes: forming a first isolation material layer between adjacent active regions and on the first face; and carrying out planarization treatment on the first isolation material layer until the first surface is exposed, and forming the isolation structure.

Optionally, the word line gate structure includes: the word line gate structure comprises a word line gate dielectric layer positioned on the side wall and the bottom surface of a word line gate groove and a word line gate layer positioned on the word line gate dielectric layer.

Optionally, the word line gate layer includes a single layer structure or a composite structure.

Optionally, when the word line gate layer is of a single-layer structure, the material of the word line gate layer includes metal or polysilicon.

Optionally, the height of the second isolation layer from the second surface to the first surface is greater than half of the height of the word line gate layer from the second surface to the first surface.

Optionally, when the word line gate layer is of a composite structure, the word line gate layer includes a first gate layer and a second gate layer located on the first gate layer, and the first gate layer and the second gate layer are made of different materials.

Optionally, the material of the first gate layer includes metal or polysilicon; the material of the second gate layer comprises polysilicon or metal.

Optionally, when the material of the first gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the first gate layer from the second surface to the first surface; when the material of the second gate layer is polysilicon, the height of the second isolation layer from the second surface to the first surface is greater than the height of the second gate layer from the second surface to the first surface.

Optionally, before forming a plurality of bit line layers, the method further includes: and forming first conductive plugs on the first source-drain doped region of each channel region, wherein each bit line layer is electrically connected with a plurality of first conductive plugs on one active region.

Optionally, before forming the plurality of capacitor structures, the method further includes: and forming a second conductive plug on each second source-drain doped region, wherein each capacitor structure is electrically connected with one second conductive plug.

Optionally, the capacitor structure includes: the electrode structure comprises a first electrode layer, a second electrode layer and a dielectric layer positioned between the first electrode layer and the second electrode layer.

Optionally, a projection of the capacitor structure from the second surface to the first surface partially overlaps with a projection of the word line gate structure from the second surface to the first surface.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the structure of the technical scheme of the invention, the bit line layer and the capacitor structure are respectively arranged on the first surface and the second surface of the substrate, so that the difficulty of circuit wiring and a manufacturing process can be effectively reduced. And the capacitor structure is arranged on the second surface of the substrate, so that the capacitor structure has larger structural space, and the storage capacity of the capacitor structure is increased. In addition, the bit line layer and the capacitor structure are respectively arranged on the first surface and the second surface of the substrate, so that the area occupied by a single storage structure can be effectively reduced, and the storage density of a memory can be improved.

In the forming method of the technical scheme of the invention, the bit line layer and the capacitor structure are respectively arranged on the first surface and the second surface of the substrate, so that the difficulty of circuit wiring and a manufacturing process can be effectively reduced. And the capacitor structure is arranged on the second surface of the substrate, so that the capacitor structure has larger structural space, and the storage capacity of the capacitor structure is increased. In addition, the bit line layer and the capacitor structure are respectively arranged on the first surface and the second surface of the substrate, so that the area occupied by a single storage structure can be effectively reduced, and the storage density of a memory can be improved.

Drawings

Fig. 1 to 17 are schematic structural diagrams of steps in an embodiment of a method for forming a dynamic random access memory according to the present invention.

Detailed Description

As described in the background, problems still exist with existing dynamic random access memories. As will be specifically described below.

In the conventional dynamic random access memory, a bit line and a conductive structure connected to the bit line are provided between the capacitor and the word line and the transistor. Therefore, in order to connect the capacitor to the word line and the transistor, the capacitor structure and the bit line and the conductive structure connected to the bit line need to be avoided from each other, which results in complicated circuit layout and difficult manufacturing process in the memory array region of the memory.

Furthermore, on the one hand, since the circuit wiring in the memory array region is complicated, the circuits other than the capacitor occupy a large area, which leads to a decrease in the storage density of the memory and a reduction in the storage capacity of the capacitor. On the other hand, since the structure of the capacitor is also affected by the structure of the logic circuit of the memory, for example, the height of a plug connecting different circuits in the logic circuit, the height of the capacitor is limited, the area of the capacitor is small, and the storage capacity of the capacitor is also small.

On the basis, the invention provides a dynamic random access memory and a forming method thereof, and the difficulty of circuit wiring and manufacturing process can be effectively reduced by respectively arranging the bit line layer and the capacitor structure on the first surface and the second surface of the substrate. And the capacitor structure is arranged on the second surface of the substrate, so that the capacitor structure has larger structural space, and the storage capacity of the capacitor structure is increased. In addition, the bit line layer and the capacitor structure are respectively arranged on the first surface and the second surface of the substrate, so that the area occupied by a single storage structure can be effectively reduced, and the storage density of a memory can be improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 1 to 17 are schematic structural diagrams illustrating a method for forming a dynamic random access memory according to an embodiment of the invention.

Referring to fig. 1 to 3, fig. 2 is a schematic cross-sectional view taken along a-a line in fig. 1, fig. 3 is a schematic cross-sectional view taken along B-B line in fig. 1, a substrate 100 is provided, the substrate 100 has a first side 101 and a second side 102 opposite to each other, the substrate 100 includes a plurality of active regions 103 that are separated from each other and parallel to a first direction X, and a plurality of the active regions 103 are arranged along a second direction Y, the first direction X is perpendicular to the second direction Y, each of the active regions 103 includes a plurality of isolation regions 104, a plurality of channel regions 105, and a plurality of word line regions 106, the isolation regions 104 and the channel regions 105 in each of the active regions 103 are arranged at intervals along the first direction X, and the word line regions 106 are located between the adjacent isolation regions 104 and the channel regions 105.

In this embodiment, the material of the substrate 100 is silicon; in other embodiments, the substrate may also be germanium, silicon carbide, gallium arsenide, or indium gallium.

In this embodiment, the channel region 105 and the word line region 106 are used to form a transistor device in the following, and the isolation region 104 is used to form a first isolation layer in the following, where the first isolation layer is used to connect only one side of a word line gate structure formed in the following with the channel region 105, so that the formed transistor is a single-sided channel structure. The dynamic random access memory with the unilateral channel structure is not easy to leak current during working, and the dynamic random access memory with the unilateral channel structure only needs to form a first conductive plug on the channel region 105 in the following process, so that the number of the first conductive plugs is effectively reduced, and the manufacturing cost is saved.

Referring to fig. 4, the views of fig. 4 and fig. 2 are in the same direction, and an isolation structure 109 is formed between adjacent active regions 103.

In this embodiment, the method for forming the isolation structure 109 includes: forming a first isolation material layer (not shown) between adjacent active regions 103 and on the first face 101; the first isolation material layer is planarized until the first side 101 is exposed, so as to form the isolation structure 109.

In this embodiment, the material of the first isolation material layer is silicon oxide.

Referring to fig. 5, the view directions of fig. 5 and fig. 3 are the same, a plurality of word line gate trenches 110 are formed in the word line region 106, the word line gate trenches 110 extend from the first surface 101 to the second surface 102, and the word line gate trenches 110 penetrate the active region 103 along the two directions Y.

In this embodiment, the word line gate trench 110 provides a space for a word line gate structure to be formed in the word line gate trench.

In this embodiment, the method for forming the word line gate trench 110 includes: forming a second patterned layer (not shown) on the first side 101 of the substrate 100, the second patterned layer exposing the word line region 106; and etching from the first surface 101 to the second surface 102 by using the second patterning layer as a mask through an etching process to form the word line gate trench 110.

Referring to fig. 6 and 7, fig. 7 is a schematic cross-sectional view taken along line C-C in fig. 6, wherein a word line gate structure 111 is formed in the word line gate trench 110.

In this embodiment, the word line gate structure 111 includes: a word line gate dielectric layer on the sidewall and bottom surfaces of the word line gate trench 110, and a word line gate layer (not labeled) on the word line gate dielectric layer.

In this embodiment, the word line gate layer has a composite structure, and includes a first gate layer and a second gate layer (not shown) on the first gate layer, where the first gate layer and the second gate layer are made of different materials.

In this embodiment, the first gate layer is made of polysilicon, and the second gate layer is made of metal; in other embodiments, the material of the first gate layer may also be a metal, and the material of the corresponding second gate layer may also be polysilicon.

In other embodiments, the word line gate layer may also adopt a single-layer structure, and when the word line gate layer adopts a single-layer structure, the material of the word line gate layer may adopt polysilicon or metal.

In this embodiment, after forming the word line gate structure, the method further includes: a dielectric layer 113 is formed on the first surface 101 of the substrate 100, the word line gate trench 110 is filled with the dielectric layer 113, and the first surface 101 of the channel region 105 is exposed by the dielectric layer 113.

Referring to fig. 8, the view directions of fig. 8 and fig. 7 are the same, and a first source/drain doped region 112 is formed in the first surface 101.

In this embodiment, the method for forming the first source/drain doped region 112 in the first surface 101 includes: and performing first ion implantation treatment from the first surface 101 to the second surface 102 by using an ion implantation process, and forming the first source/drain doped region 112 on the first surface 101.

In the embodiment, the first ions are N-type ions; in other embodiments, the first ions may also be P-type ions.

Referring to fig. 9 and 10, fig. 10 is a schematic cross-sectional view taken along line D-D in fig. 9, a plurality of bit line layers 114 parallel to the first direction X are formed on the first surface 101, and each of the bit line layers 114 is electrically connected to the first source/drain doped regions 112 of the channel regions 105 in one of the active regions 103.

In the present embodiment, before forming several bit line layers 114, the method further includes: forming first conductive plugs 115 on the first source-drain doped regions 112 of each of the channel regions 105, wherein each of the bit line layers 114 is electrically connected to a plurality of the first conductive plugs 115 on one of the active regions 103; in other embodiments, the first conductive plug may not be formed.

The bit line layer 114 material comprises a metal including tungsten, aluminum, copper, and the like. In this embodiment, the bit line layer 114 is made of tungsten.

In this embodiment, the method for forming the bit line layer 114 includes: forming a bit line material layer (not shown) on the first face 101; forming a third patterned layer (not shown) on the bit line material layer, the third patterned layer exposing a portion of the bit line material layer; and etching the bit line material layer from the first surface 101 to the second surface 102 by using the third patterned layer as a mask to form a plurality of bit line layers 114.

The process for forming the bit line material layer comprises the following steps: a metal plating process, a selective metal growth process or a deposition process; the deposition process comprises a chemical vapor deposition process, a physical vapor deposition process or an atomic layer deposition process. In this embodiment, the bit line material layer is formed by an atomic layer deposition process.

Referring to fig. 11, the view directions of fig. 11 and fig. 10 are the same, and a second source/drain doped region 116 is formed in each of the second faces 102.

In this embodiment, the method for forming the second source/drain doped region 116 in the second surface 102 includes: and performing second ion implantation treatment from the second surface 102 to the first surface 101 by using an ion implantation process, and forming the second source/drain doped region 116 on the second surface 102.

In the embodiment, the second ions are different from the first ions in electric type, and the second ions are P-type ions; in other embodiments, when the first ions are P-type ions, the second ions may also be N-type ions.

From there, transistors are formed within the substrate 100.

Referring to fig. 12, the substrate 100 is thinned from the second side 102 toward the first side 101.

The process of thinning the substrate from the second surface 102 to the first surface 101 includes a physical mechanical polishing process, a chemical mechanical polishing process, or a wet etching process. In this embodiment, the process of thinning the substrate from the second surface 102 to the first surface 101 is a chemical mechanical polishing process.

In this embodiment, the thinning process is performed until the surface of the isolation structure 109 is exposed.

Referring to fig. 13, the isolation region 104 is etched from the second surface 102 toward the first surface 101, and a plurality of first isolation openings 107 parallel to the second direction Y are formed in the substrate 100.

In this embodiment, the method for forming the first isolation opening 107 includes: forming a first patterned layer (not shown) on the second side 102 of the substrate 100, the first patterned layer exposing the isolation regions 104; and etching from the second surface 102 to the first surface 101 by using the first patterning layer as a mask through an etching process to form the first isolation opening 107.

In the present embodiment, the first isolation opening 107 is formed after the active region 103 is formed; in other embodiments, the first isolation opening may also be formed simultaneously with the active region.

In this embodiment, the first isolation opening 107 penetrates the first surface 101 from the second surface 102; in other embodiments, the first isolation opening may not extend through the first surface from the second surface, as long as a first isolation layer formed in the first isolation opening subsequently can block an adjacent channel region.

Referring to fig. 14, a first isolation layer 108 is formed in the first isolation opening 107.

In this embodiment, the method for forming the first isolation layer 108 includes: forming a second isolation material layer (not shown) within the first isolation opening 107 and on the second side 102; the second isolation material layer is planarized until the second surface 102 is exposed, thereby forming the first isolation layer 108.

In this embodiment, the material of the second isolation material layer is silicon oxide.

Referring to fig. 15, a portion of the channel region 105 is etched from the second surface 102 toward the first surface 101, and a second isolation opening 117 is formed in the channel region 105.

In this embodiment, the second isolation opening 117 is used to provide a space for a subsequently formed second isolation layer, and the method for forming the second isolation opening 117 includes: forming a fourth patterned layer (not shown) on the second side 102, the fourth patterned layer exposing a portion of the surface of the channel region 105; etching from the second surface 102 to the first surface 101 using the fourth patterned layer as a mask, and forming the second isolation opening 117 in the channel region 105.

Referring to fig. 16, a second isolation layer 118 is formed in the second isolation opening 117.

In this embodiment, the second isolation layer 118 is used to isolate the adjacent transistors and prevent the transistors from being connected in series.

In this embodiment, the material of the second isolation layer 118 is silicon oxide.

In this embodiment, the second isolation layer 118 is formed after the first isolation layer 108; in other embodiments, the first isolation layer and the second isolation layer may be formed simultaneously, that is, the first isolation opening and the second isolation opening are formed first, then the first isolation opening and the second isolation opening are filled with an isolation material simultaneously, and finally the first isolation layer and the second isolation layer are formed simultaneously by a planarization process.

In this embodiment, since the material of the first gate layer is polysilicon and the material of the second gate layer is metal, in order to ensure that the second isolation layer 118 completely blocks the adjacent transistors, the height of the second isolation layer 118 from the second surface 102 toward the first surface 101 is greater than the height of the first gate layer from the second surface 102 toward the first surface 101.

In other embodiments, when the material of the second gate layer is polysilicon, a height of the second isolation layer from the second surface to the first surface is greater than a height of the second gate layer from the second surface to the first surface.

In other embodiments, when the word line gate layer has a single-layer structure, the height of the second isolation layer from the second surface to the first surface is greater than half of the height of the word line gate layer from the second surface to the first surface.

Referring to fig. 17, a plurality of capacitor structures 119 are formed on the second surface 102, and each capacitor structure 119 is electrically connected to one of the second source/drain doped regions 116.

In this embodiment, the bit line layer 114 and the capacitor structure 119 are respectively disposed on the first surface 101 and the second surface 102 of the substrate 100, so that the difficulty of circuit wiring and manufacturing processes can be effectively reduced. Furthermore, the capacitor structure 119 is disposed on the second surface 102 of the substrate 100, so that the capacitor structure 119 has a larger structural space, and the storage capacity of the capacitor structure 119 is increased. In addition, the bit line layer 114 and the capacitor structure 119 are respectively arranged on the first surface 101 and the second surface 102 of the substrate 100, so that the area occupied by a single memory structure can be effectively reduced, and the memory density of the memory can be improved.

In this embodiment, one capacitor structure 119 and one transistor are arranged in a two-dimensional matrix as a unit. The basic operation mechanism is divided into Read (Read) and Write (Write), in which the bit line layer 114 is first charged to half of the operation voltage and then the transistor is turned on to cause the bit line layer 114 and the capacitor structure 119 to share charges. If the internally stored value is 1, the voltage of the bit line layer 114 is raised by charge sharing to more than half of the operating voltage; on the other hand, if the internally stored value is 0, the voltage of the bit line layer 114 is pulled down to be lower than half of the operating voltage, and after the voltage of the bit line layer 114 is obtained, the internal values are determined to be 0 and 1 through an amplifier. The transistor is turned on when writing, and if 1 is to be written, the voltage of the bit line layer 114 is raised to an operating voltage to store the operating voltage on the capacitor structure 119; if a 0 is to be written, then lowering the bit line layer 114 to 0 volts leaves no charge inside the capacitive structure 119.

In this embodiment, before forming the plurality of capacitor structures 119, the method further includes: forming a second conductive plug 120 on each second source-drain doped region 116, wherein each capacitor structure 119 is electrically connected to one second conductive plug 120; in other embodiments, the second conductive plug may not be formed.

In this embodiment, the capacitor structure 119 includes: a first electrode layer, a second electrode layer, and a dielectric layer (not labeled) between the first electrode layer and the second electrode layer.

In this embodiment, a projection of the capacitor structure 119 from the second surface 102 to the first surface 101 partially overlaps a projection of the word line gate structure 111 from the second surface 102 to the first surface 101.

Accordingly, the embodiment of the present invention further provides a dynamic random access memory, please refer to fig. 17, which includes: a substrate 100, the substrate 100 having a first side 101 and a second side 102 opposite to each other, the substrate 100 including a plurality of active regions 103 separated from each other and parallel to a first direction X, and a plurality of active regions 103 arranged along a second direction Y, the first direction X being perpendicular to the second direction Y, each of the active regions 103 including a plurality of isolation regions 104, a plurality of channel regions 105, and a plurality of word line regions 106, the isolation regions 104 and the channel regions 105 in each of the active regions 103 being arranged at intervals along the first direction X, and the word line regions 106 being located between adjacent isolation regions 104 and channel regions 105; a word line gate structure 111 located in the word line region 106, wherein the word line gate structure 111 extends from the first side 101 to the second side 102, and the word line gate structure 111 penetrates the active region 103 along the second direction Y; a first source-drain doped region 112 located in the first side 101 of the channel region 105; a plurality of bit line layers 114 parallel to the first direction X on the first surface 101, each of the bit line layers 114 being electrically connected to a plurality of first source/drain doped regions 112 in one of the active regions 103; a second source-drain doped region 116 located in the second surface 103 of the channel region 105; a first isolation layer 108 located within the isolation region 104, the first isolation layer 108 penetrating the substrate 100 in a direction from the first side 101 to the second side 102; a second isolation layer 118 located within the channel region 105, the second isolation layer 118 extending from the second face 102 in a direction toward the first face 101; a plurality of capacitor structures 119 located on the second surface 102, wherein each capacitor structure 119 is electrically connected to one of the second source/drain doped regions 116.

In this embodiment, the bit line layer 114 and the capacitor structure 119 are respectively disposed on the first surface 101 and the second surface 102 of the substrate 100, so that the difficulty of circuit wiring and manufacturing processes can be effectively reduced. Furthermore, the capacitor structure 119 is disposed on the second surface 102 of the substrate 100, so that the capacitor structure 119 has a larger structural space, and the storage capacity of the capacitor structure 119 is increased. In addition, the bit line layer 114 and the capacitor structure 119 are respectively arranged on the first surface 101 and the second surface 102 of the substrate 100, so that the area occupied by a single memory structure can be effectively reduced, and the memory density of the memory can be improved.

In this embodiment, the method further includes: isolation structures 109 located between adjacent active regions 103, the isolation structures 109 penetrating the substrate 100 in a direction from the first side 101 to the second side 102.

In this embodiment, the word line region 106 has a word line gate trench 109, the word line gate trench 110 extends from the first surface 101 to the second surface 102, and the word line gate trench 110 penetrates the active region 103 along the two directions Y; the word line gate structure 111 includes a word line gate dielectric layer on the sidewall and bottom surface of the word line gate trench 110, and a word line gate layer on the word line gate dielectric layer.

In this embodiment, the word line gate layer has a composite structure, and when the word line gate layer has the composite structure, the word line gate layer includes a first gate layer and a second gate layer located on the first gate layer, where the first gate layer and the second gate layer are made of different materials.

In this embodiment, the first gate layer is made of polysilicon, and the second gate layer is made of metal; in other embodiments, the material of the first gate layer may also be a metal, and the material of the second gate layer may also be polysilicon.

In this embodiment, when the material of the first gate layer is polysilicon, the height of the second isolation layer 118 from the second surface 102 to the first surface 101 is greater than the height of the first gate layer from the second surface 102 to the first surface 101.

In other embodiments, when the material of the second gate layer is polysilicon, a height of the second isolation layer from the second surface to the first surface is greater than a height of the second gate layer from the second surface to the first surface.

In other embodiments, the word line gate layer may also adopt a single-layer structure, and when the word line gate layer is of the single-layer structure, the material of the word line gate layer includes metal or polysilicon.

In other embodiments, when the word line gate layer adopts a single-layer structure, the height of the second isolation layer from the second surface to the first surface is greater than half of the height of the word line gate layer from the second surface to the first surface.

In this embodiment, the method further includes: a first conductive plug 115 located on each of the first source-drain doped regions 112, wherein each of the bit line layers 114 is electrically connected to a plurality of the first conductive plugs 115 located on one of the active regions 103.

In this embodiment, the method further includes: and a second conductive plug 120 located on each second source-drain doped region 116, wherein each capacitor structure 119 is electrically connected to one second conductive plug 120.

In this embodiment, the capacitor structure 119 includes: the electrode structure comprises a first electrode layer, a second electrode layer and a dielectric layer positioned between the first electrode layer and the second electrode layer.

In this embodiment, a projection of the capacitor structure 119 from the second surface 102 to the first surface 101 partially overlaps a projection of the word line gate structure 111 from the second surface 102 to the first surface 101.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.