Semiconductor Structure and Method of Forming the Same

Abstract

The present disclosure relates to the field of semiconductor technology, and relates to a semiconductor structure and a method for forming the same. The forming method includes: providing a substrate; etching the substrate to form a plurality of first trenches distributed at intervals; forming a first filling layer, the first filling layer filling the first trenches and covering the surface of the etched substrate; etching a part of the first trenches to form a plurality of second trenches, and there is a first trench filled with the first filling layer between two adjacent second trenches; forming a second filling layer, the second filling layer filling the second trenches; etching the remaining first trenches to form third trenches, and there is a second trench filled with the second filling layer between two adjacent third trenches; forming a third filling layer, the third filling layer filling the third trenches. The forming method of the present disclosure can significantly reduce the probability of collapse of the active region and improve the product yield.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and more particularly, to a semiconductor structure and a method for forming the same. Background Art

[0002] Memory is widely used in mobile devices such as mobile phones and tablet computers due to its advantages of small size, high integration level, and fast transmission speed. The active region is one of the important components of the memory and plays a crucial role in the performance of the device. However, as the device size continues to shrink, during the manufacturing process of the active region, due to the influence of the formation process, structural defects such as collapse are likely to occur, resulting in a low product yield.

[0003] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] In view of this, the present disclosure provides a semiconductor structure and a method for forming the same, which can significantly reduce the probability of collapse in the active region and improve the product yield.

[0005] According to one aspect of the present disclosure, a method for forming a semiconductor structure is provided, including:

[0006] Providing a substrate;

[0007] Etching the substrate to form a plurality of first trenches spaced apart from each other;

[0008] Forming a first filling layer, the first filling layer filling the first trenches and covering the surface of the etched substrate;

[0009] Etching a part of the first trenches to form a plurality of second trenches, and there is a first trench filled with the first filling layer between two adjacent second trenches;

[0010] Forming a second filling layer, the second filling layer filling the second trenches;

[0011] Etching the remaining first trenches to form third trenches, and there is a second trench filled with the second filling layer between two adjacent third trenches;

[0012] Forming a third filling layer, the third filling layer filling the third trenches.

[0013] In an exemplary embodiment of the present disclosure, the etching a part of the first trenches to form a plurality of second trenches, and there is a first trench filled with the first filling layer between two adjacent second trenches, includes:

[0014] A first mask layer is formed on a side of the first filling layer away from the substrate. The first mask layer includes a plurality of first mask regions distributed at intervals and first etching regions located on opposite sides of the first mask regions. A positive projection of the first etching region on the substrate coincides with a positive projection of a part of the first trenches on the substrate, and a positive projection of the first mask region on the substrate covers a positive projection of the remaining first trenches on the substrate;

[0015] Using the first mask region as a mask, the first etching region, the first filling layer located directly below the first etching region, and the first trenches located directly below the first etching region are etched to form the second trenches in the substrate.

[0016] In an exemplary embodiment of the present disclosure, the forming method further includes:

[0017] Before forming the second filling layer, the remaining first mask layer is removed;

[0018] The forming of the second filling layer, where the second filling layer fills the second trenches, includes:

[0019] A second filling layer is formed on a surface of a structure jointly formed by the first filling layer and the second trenches, and the second filling layer fills the second trenches.

[0020] In an exemplary embodiment of the present disclosure, the etching of the remaining first trenches to form third trenches, with the second trenches filled with the second filling layer between any two adjacent third trenches, includes:

[0021] A second mask layer is formed on a side of the second filling layer away from the substrate. The second mask layer includes a plurality of second mask regions distributed at intervals and second etching regions located on opposite sides of the second mask regions. A positive projection of the second etching region on the substrate coincides with a positive projection of the remaining first trenches on the substrate, and a positive projection of the second mask region on the substrate covers a positive projection of the second trenches on the substrate;

[0022] Using the second mask region as a mask, the second etching region, the first filling layer located directly below the second etching region, and the first trenches located directly below the second etching region are etched to form the third trenches in the substrate.

[0023] In an exemplary embodiment of the present disclosure, before etching the remaining first trenches, one of the first trenches is provided between any two adjacent ones of the plurality of second trenches.

[0024] In an exemplary embodiment of the present disclosure, etching the substrate to form a plurality of first trenches spaced apart includes:

[0025] Etching the substrate to form a plurality of initial active groups spaced along a first direction, with the first trenches between adjacent initial active groups; each initial active group includes a plurality of initial active regions spaced along a second direction; with the initial active regions as a reference, two adjacent initial active groups are aligned, and two adjacent first trenches communicate through a first gap between two adjacent initial active regions distributed along the second direction; each of the first trenches and each of the first gaps define the initial active regions as columnar structures, and the second direction is perpendicular to the first direction.

[0026] In an exemplary embodiment of the present disclosure, etching the substrate to form a plurality of first trenches spaced apart includes:

[0027] Etching the substrate to form a plurality of initial active groups spaced along a first direction, with the first trenches between adjacent initial active groups; each initial active group includes a plurality of initial active regions extending along a second direction and spaced along the second direction; with the initial active regions as a reference, two adjacent initial active groups are staggeredly distributed, and two adjacent first trenches communicate through a second gap between two adjacent initial active regions distributed along the second direction; the second direction intersects the first direction.

[0028] In an exemplary embodiment of the present disclosure, using the second gap as a connection region, the connection region and the first trenches are alternately distributed in sequence; the first filling layer also fills the connection region;

[0029] The forming method further includes:

[0030] After forming the third filling layer, etching the first filling layer and the connection region located in the connection region to increase the depth of the connection region in the substrate;

[0031] Forming a fourth filling layer, and the fourth filling layer fills the connection region with an increased depth.

[0032] In an exemplary embodiment of the present disclosure, after forming the third filling layer, etching the first filling layer and the connection region located in the connection region to increase the depth of the connection region in the substrate includes:

[0033] Forming a third mask layer on a side of the first filling layer, the second filling layer, and the third filling layer away from the substrate;

[0034] A photoresist layer is formed on a side of the third mask layer away from the substrate. The photoresist layer includes a plurality of developing regions, and the orthographic projections of the respective developing regions on the substrate coincide with the orthographic projections of the respective connection regions on the substrate.

[0035] Etch the first filling layer and the connection region directly below the first filling layer in the developing region to increase the depth of the connection region in the substrate.

[0036] In an exemplary embodiment of the present disclosure, forming the first mask layer on a side of the first filling layer away from the substrate includes:

[0037] Form a first mask material layer on a side of the first filling layer away from the substrate;

[0038] Etch the first mask material layer to form a plurality of first mask structures distributed at intervals;

[0039] Form a first etching material layer on sidewalls of the first mask structures to serve as the first etching region;

[0040] Fill a first filling material between structures jointly constituted by the first mask structures and the first etching region to form a plurality of second mask structures distributed at intervals. The first mask structures and the second mask structures jointly constitute the first mask region.

[0041] In an exemplary embodiment of the present disclosure, forming the second mask layer on a side of the second filling layer away from the substrate includes:

[0042] Form a second mask material layer on a side of the second filling layer away from the substrate;

[0043] Etch the second mask material layer to form a plurality of third mask structures distributed at intervals;

[0044] Form a second etching material layer on sidewalls of the third mask structures to serve as the second etching region;

[0045] Fill a second filling material between structures jointly constituted by the third mask structures and the second etching region to form a plurality of fourth mask structures distributed at intervals. The third mask structures and the fourth mask structures jointly constitute the second mask region.

[0046] In an exemplary embodiment of the present disclosure, the forming method further includes:

[0047] Clean the second trench before forming the second filling layer;

[0048] Before forming the third filling layer, clean the third trench.

[0049] In an exemplary embodiment of the present disclosure, the aspect ratio of the first trench is 10:1 to 8:1.

[0050] In an exemplary embodiment of the present disclosure, the aspect ratio of the second trench is 16:1 to 20:1; and / or the aspect ratio of the third trench is 16:1 to 20:1.

[0051] According to one aspect of the present disclosure, there is provided a semiconductor structure formed by the method for forming a semiconductor structure described in any one of the above. The semiconductor structure includes a plurality of active regions divided by the second trench, the third trench, and a plurality of connection regions connecting between the second trench and the third trench. Filling layers are provided in the second trench, the third trench, and the connection region; the active region includes a first sidewall and a second sidewall that are oppositely disposed, the first sidewall and the second sidewall are parallelly distributed, and both the first sidewall and the second sidewall extend in a direction perpendicular to the bottom surface of the substrate; the aspect ratio of the second trench is 16:1 to 20:1; and / or the aspect ratio of the third trench is 16:1 to 20:1.

[0052] The semiconductor structure and its forming method of the present disclosure can reduce the capillary force between patterns (such as active region patterns) of the semiconductor structure in the cleaning process by means of step-by-step etching and gradual filling of the filling layer, inhibit the collapse of high aspect ratio patterns (such as active region patterns) during the cleaning process, and do not need to use supercritical cleaning or add various surfactants, thereby reducing the equipment cost and improving the product yield. Specifically, the substrate is etched by means of step-by-step etching to form a second trench and a third trench with a relatively large aspect ratio, and then an active region is defined by the second trench, the third trench, and a plurality of connection regions connecting the second trench and the third trench. In this process, the substrate can be first etched to form a first trench with a relatively small aspect ratio, and then a first filling layer is filled into the first trench; a part of the first trench is etched to form a plurality of second trenches. Since there is a first trench filled with the first filling layer between adjacent second trenches, during the subsequent cleaning process of the second trench with a relatively large aspect ratio, the first filling layer can support the remaining substrate (i.e., the side wall of the second trench) on at least one side of the second trench, reducing the probability of the side wall of the second trench collapsing due to the action of capillary force, which helps to improve the product yield. At the same time, after the second filling layer is formed, the remaining first trench is etched to form a third trench. Since there is a second trench filled with the second filling layer between any two adjacent third trenches, during the subsequent cleaning process of the third trench with a relatively large aspect ratio, the second filling layer can support the remaining substrate (i.e., the side wall of the third trench) on at least one side of the third trench, reducing the probability of the side wall of the third trench collapsing due to the action of capillary force. That is, the present application can reduce the collapse probability of the active region defined by the second trench, the third trench, and a plurality of connection regions connecting the second trench and the third trench, improve the product yield, and do not need to use supercritical cleaning or add various surfactants, reducing the equipment cost. In addition, the second filling layer and the third filling layer can directly serve as the trench isolation structure between the active regions. That is, the design of the second filling layer and the third filling layer can not only reduce the collapse probability of the active regions, but also form the trench isolation structure simultaneously during the formation of the active regions, so that it is not necessary to form the trench isolation structure through a separate process subsequently, which can simplify the process and reduce the cost.

[0053] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Brief Description of the Drawings

[0054] The accompanying drawings here are incorporated into and form a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0055] Figure 1 It is a flowchart of a method for forming a semiconductor structure in an embodiment of the present disclosure.

[0056] Figure 2 It is a schematic structural diagram after completing step S120 in an embodiment of the present disclosure.

[0057] Figure 3 It is a schematic structural diagram after completing step S120 in another embodiment of the present disclosure.

[0058] Figure 4 It is a cross-sectional view taken along the aa' direction in Figure 2 or along the bb' direction in Figure 3

[0059] Figure 5 It is a cross-sectional view taken along the Figure 3 cc' direction.

[0060] Figure 6 It is a cross-sectional view taken along the aa' direction in Figure 2 or along the bb' direction in Figure 3 after completing step S130.

[0061] Figure 7 It is a cross-sectional view taken along the Figure 3 cc' direction after completing step S130.

[0062] Figure 8 It is a cross-sectional view taken along the aa' direction in Figure 2 or along the bb' direction in Figure 3 after completing step S140.

[0063] Figure 9 It is a cross-sectional view taken along the Figure 3 cc' direction after completing step S140.

[0064] Figure 10 It is a cross-sectional view taken along the aa' direction in Figure 2 or along the bb' direction in Figure 3 after completing step S210.

[0065] Figure 11 It is a cross-sectional view taken along the Figure 3 cc' direction after completing step S210.​

[0066] Figure 12 A cross-sectional view taken along the aa' direction or the bb' direction in the present disclosure after forming the first mask material layer and the first photoresist layer. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0067] Figure 13 A cross-sectional view taken along the cc' direction in the present disclosure after forming the first mask material layer and the first photoresist layer. Figure 3 in the cross-sectional view.

[0068] Figure 14 A cross-sectional view taken along the aa' direction or the bb' direction in the present disclosure after forming the first etching material layer. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0069] Figure 15 A cross-sectional view taken along the cc' direction in the present disclosure after forming the first etching material layer. Figure 3 in the cross-sectional view.

[0070] Figure 16 A cross-sectional view taken along the aa' direction or the bb' direction in the present disclosure after forming the first filling material. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0071] Figure 17 A cross-sectional view taken along the cc' direction in the present disclosure after forming the first filling material. Figure 3 in the cross-sectional view.

[0072] Figure 18 A cross-sectional view taken along the aa' direction or the bb' direction in the present disclosure after forming the second filling layer. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0073] Figure 19 A cross-sectional view taken along the cc' direction in the present disclosure after forming the second filling layer. Figure 3 in the cross-sectional view.

[0074] Figure 20 A cross-sectional view taken along the aa' direction or the bb' direction in the present disclosure after completing step S160. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0075] Figure 21 A cross-sectional view taken along the aa' direction or the bb' direction after completing step S410. Figure 2 in the aa' direction or along Figure 3 the bb' direction in the cross-sectional view.

[0076] Figure 22 The cross-sectional view taken along the Figure 3 cc' direction after step S410 is completed.

[0077] Figure 23 The cross-sectional view taken along the Figure 2 aa' direction or along the Figure 3 bb' direction in the present disclosure after the second mask material layer and the second photoresist layer are formed.

[0078] Figure 24 The cross-sectional view taken along the Figure 3 cc' direction in the present disclosure after the second mask material layer and the second photoresist layer are formed.

[0079] Figure 25 The cross-sectional view taken along the Figure 2 aa' direction or along the Figure 3 bb' direction in the present disclosure after the third mask structure is formed.

[0080] Figure 26 The cross-sectional view taken along the Figure 2 aa' direction or along the Figure 3 bb' direction in the present disclosure after the second etching material layer and the second filling material are formed.

[0081] Figure 27 The cross-sectional view taken along the Figure 2 aa' direction or along the Figure 3 bb' direction after step S170 is completed.

[0082] Figure 28 The cross-sectional view taken along the Figure 3 cc' direction in the present disclosure after the third mask layer and the photoresist layer are formed.

[0083] Figure 29 The cross-sectional view taken along the Figure 3 cc' direction after step S630 is completed.

[0084] Figure 30 The cross-sectional view taken along the Figure 3 cc' direction after step S190 is completed.

[0085] Explanation of reference numerals:

[0086] 1. Substrate; 101. First trench; 102. Second trench; 103. Third trench; 11. Initial active group; 111. Initial active region; 112. First gap; 113. Second gap; 114. Active region; 115. Connection region; 21. First filling layer; 22. Second filling layer; 23. Third filling layer; 24. Fourth filling layer; 31. First mask layer; 301. First sub-mask layer; 302. Second sub-mask layer; 303. Third sub-mask layer; 304. Fourth sub-mask layer; 305. Fifth sub-mask layer; 306. Sixth sub-mask layer; 311. First mask material layer; 3111. First mask structure; 312. First etching material layer; 313. First filling material; 3131. Second mask structure; 314. First mask region; 315. First etching region; 32. Second mask layer; 321. Second mask material layer; 3211. Third mask structure; 322. Second etching material layer; 323. Second filling material; 3231. Fourth mask structure; 324. Second mask region; 325. Second etching region; 33. Third mask layer; 4. Photoresist layer; 41. Development region; x. First direction; y. Second direction; 51. First photoresist layer; 52. Second photoresist layer. Detailed implementation manners

[0087] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0088] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of an icon to another component, these terms are used in this specification only for convenience, for example, according to the directions of the examples described in the drawings. It can be understood that if the device of the icon is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" another structure, it may mean that a structure is integrally formed on another structure, or that a structure is "directly" disposed on another structure, or that a structure is "indirectly" disposed on another structure through another structure.

[0089] The terms "a", "an", "the", "said", and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "comprising" and "having" are used to mean an open inclusion and refer to the possible existence of additional elements / components / etc. in addition to the listed elements / components / etc.; the terms "first", "second", "third", "fourth", etc. are used only as labels and do not limit the quantity of their objects.

[0090] The manufacturing process of the active region of a semiconductor structure and the trench isolation structure generally includes: etching a substrate to form trenches, dividing the substrate into multiple spaced-apart active regions through the trenches, cleaning the sidewalls of the trenches, and then filling the trenches with an insulating material to form a trench isolation structure. However, in order to ensure the isolation effect between the active regions, the aspect ratio of the trenches is often large (usually greater than 15). During the process of cleaning the trenches, the active region patterns on the sidewalls of the trenches are likely to collapse or deform under the action of capillary force, seriously affecting the product yield. In related technologies, supercritical fluid drying is usually used to reduce or eliminate the surface tension or capillary force of the cleaning liquid to prevent the collapse of the active regions, but this requires high equipment requirements and high costs. Or, various surfactants are added to the cleaning liquid to reduce the surface tension or capillary force, but the surfactant in the cleaning liquid will remain on the surface of the wafer, affecting the product yield.

[0091] Based on this, the embodiments of the present disclosure provide a method for forming a semiconductor structure, as Figure 1 shown, the forming method includes steps S110 - S170, where:

[0092] Step S110, providing a substrate;

[0093] Step S120, etching the substrate to form a plurality of spaced-apart first trenches;

[0094] Step S130, forming a first filling layer, the first filling layer filling the first trenches and covering the surface of the etched substrate;

[0095] Step S140, etching some of the first trenches to form a plurality of second trenches, and there is a first trench filled with the first filling layer between two adjacent second trenches;

[0096] Step S150, forming a second filling layer, the second filling layer filling the second trenches;

[0097] Step S160, etching the remaining first trenches to form a plurality of third trenches, and there is a second trench filled with the second filling layer between two adjacent third trenches;

[0098] Step S170, forming a third filling layer, the third filling layer filling the third trenches.

[0099] A method for forming a semiconductor structure according to the present disclosure can reduce the capillary force between patterns (such as active region patterns) of the semiconductor structure in the cleaning process by means of step-by-step etching and gradual filling of filling layers, inhibit the collapse of high aspect ratio patterns (such as active region patterns) during the cleaning process, and does not require the use of supercritical cleaning or the addition of various surfactants, thereby reducing equipment costs and improving product yield. Specifically, the substrate is etched by means of step-by-step etching to form a second trench and a third trench with a large aspect ratio, and then an active region is defined by the second trench, the third trench, and a plurality of connection regions connecting the second trench and the third trench. During this process, the substrate can be first etched to form a first trench with a small aspect ratio, and then a first filling layer is filled into the first trench; a part of the first trench is etched to form a plurality of second trenches. Since there is a first trench filled with the first filling layer between adjacent second trenches, during the subsequent cleaning process of the second trench with a large aspect ratio, the first filling layer can support at least one side of the remaining substrate (i.e., the sidewall of the second trench) of the second trench, reducing the probability of the sidewall of the second trench collapsing due to the capillary force during the cleaning process of the second trench, which helps to improve product yield. At the same time, after the second filling layer is formed, the remaining first trench is etched to form a third trench. Since there is a second trench filled with the second filling layer between two adjacent third trenches, during the subsequent cleaning process of the third trench with a large aspect ratio, the second filling layer can support at least one side of the remaining substrate (i.e., the sidewall of the third trench) of the third trench, reducing the probability of the sidewall of the third trench collapsing due to the capillary force during the cleaning process of the third trench. That is, the present application can reduce the collapse probability of the active region defined by the second trench, the third trench, and a plurality of connection regions connecting the second trench and the third trench, improve product yield, and does not require the use of supercritical cleaning or the addition of various surfactants, reducing equipment costs. In addition, the second filling layer and the third filling layer can directly serve as the trench isolation structure between active regions. That is, the design of the second filling layer and the third filling layer can not only reduce the collapse probability of the active region, but also form the trench isolation structure simultaneously during the formation of the active region, so that it is not necessary to form the trench isolation structure through a separate process subsequently, which can simplify the process and reduce costs.

[0100] The following details the specific steps and implementation details of the method for forming a semiconductor structure according to the present disclosure:

[0101] As Figure 1 shown, in step S110, a substrate is provided.

[0102] The substrate may have a flat structure, which can be rectangular, circular, oval, polygonal or irregular in shape. Its material can be a semiconductor material. For example, its material can be silicon, but it is not limited to silicon or other semiconductor materials. No special limitations are imposed on the shape and material of the substrate herein.

[0103] As Figure 1 shown, in step S120, the substrate is etched to form a plurality of first trenches spaced apart from each other.

[0104] As Figure 2 and Figure 3 shown, the first trench 101 can be strip-shaped. For example, the first trenches 101 can be spaced apart along the first direction x and extend along the second direction y. The substrate 1 can be etched by an anisotropic etching process (e.g., dry etching) to form a plurality of first trenches 101 spaced apart along the first direction x (as Figure 4 and Figure 5 shown).

[0105] Both the first direction x and the second direction y can be directions parallel to the bottom surface of the substrate 1, and the second direction y can intersect the first direction x. For example, the second direction y and the first direction x can be perpendicular to each other. It should be noted that perpendicularity can be absolute perpendicularity or approximately perpendicular. There will inevitably be deviations during the manufacturing process. In the present disclosure, due to process limitations in manufacturing, there may be angular deviations, resulting in a certain deviation in the angle between the second direction y and the first direction x. As long as the angular deviation between the second direction y and the first direction x is within a preset range, the second direction y can be considered perpendicular to the first direction x. For example, the preset range can be 10°, that is: when the angle between the second direction y and the first direction x is greater than or equal to 80° and less than or equal to 100°, the second direction y and the first direction x can be considered perpendicular.

[0106] In an exemplary embodiment of the present disclosure, please continue to refer to Figure 2 and Figure 3 shown. By etching the substrate 1, the substrate 1 can be divided into a plurality of initial active groups 11 spaced apart along the first direction x, and the first trench 101 is located between adjacent initial active groups 11; that is, the plurality of initial active groups 11 and the plurality of first trenches 101 are alternately distributed along the first direction x. For example, a first trench 101 is provided between every two adjacent initial active groups 11. At the same time, an initial active group 11 is provided between every two adjacent first trenches 101.

[0107] In some embodiments of the present disclosure, please continue to refer to Figure 2As shown, each initial active group 11 includes a plurality of initial active areas 111 spaced apart along the second direction y; the gaps between adjacent initial active areas 111 spaced apart along the second direction y can be defined as first gaps 112. Taking the initial active area 111 as a reference, two adjacent initial active groups 11 are aligned, and two adjacent first grooves 101 can be connected through the first gaps 112 between the two adjacent initial active areas 111 spaced apart along the second direction y; and each first gap 112 spaced apart along the second direction y is connected to the first grooves 101 on both sides thereof, and each first groove 101 and each first gap 112 define the initial active area 111 as a columnar structure, and each columnar initial active area 111 is arrayed in the form of rows and columns. That is, the second direction is perpendicular to the first direction.

[0108] In other embodiments of the present disclosure, please continue to refer to Figure 3 As shown, each initial active group 11 includes a plurality of initial active areas 111 extending along the second direction y and spaced apart along the second direction y, and the gaps between adjacent initial active areas 111 spaced apart along the second direction y may be defined as second gaps 113. Taking the initial active area 111 as a reference, two adjacent initial active groups 11 may be staggered, and two adjacent first trenches 101 may be connected through the second gaps 113 between the two adjacent initial active areas 111 spaced apart along the second direction y; and each second gap 113 spaced apart along the second direction y is connected to the first trenches 101 on both sides thereof, and each first trench 101 and each second gap 113 define the initial active area 111 as a block structure, and the cross section of the block structure is a strip.

[0109] In an exemplary embodiment of the present disclosure, the aspect ratio of the first trench 101 may be 10:1 to 8:1, for example, the aspect ratio may be 8:1, 8.5:1, 9:1, 9.5:1, 10:1, and of course, the aspect ratio of the first trench 101 may be other ratios, which are not listed here. For example, when the aspect ratios of the second trench 102 and the third trench 103 to be formed are 16:1 to 20:1, the aspect ratio of the first trench 101 may be 10:1 to 8:1.

[0110] In some embodiments of the present disclosure, after forming the first groove 101, the first groove 101 may be cleaned to remove impurities. In this process, since the first groove 101 has a small depth-to-width ratio, it generally does not collapse or deform. Therefore, it is not necessary to use a supercritical fluid drying device for drying during this cleaning process, and the manufacturing cost is low. At the same time, it is not necessary to add a surfactant to the cleaning liquid to reduce surface tension or capillary force, and there is less residue, which has less impact on product yield.

[0111] like Figure 1As shown, in step S130, a first filling layer is formed, and the first filling layer fills the first trenches and covers the surface of the etched substrate.

[0112] The material of the first filling layer 21 can be an insulating material. For example, the material can be silicon oxide, silicon nitride, silicon oxynitride, etc. The first filling material layer can be formed on the surface of the substrate 1 having the first trenches 101 by chemical vapor deposition, physical vapor deposition, atomic layer deposition, or the like. The first filling material layer can fill each of the first trenches 101. Chemical mechanical polishing can be performed on the first filling material layer so that the thicknesses of the regions on its surface are substantially the same, and the remaining first filling material layer after chemical mechanical polishing can be used as the first filling layer 21. In some embodiments of the present disclosure, after step S130 is completed, the cross-sectional structure cut along the aa' direction in Figure 2 or along the bb' direction in Figure 3 is as shown in Figure 6 ; the cross-sectional structure cut along the cc' direction in Figure 3 after step S130 is completed is as shown in Figure 7 .

[0113] As Figure 1 shown, in step S140, some of the first trenches are etched to form a plurality of second trenches, and there is a first trench filled with the first filling layer between any two adjacent second trenches.

[0114] The aspect ratio of the second trenches 102 can be 16:1 to 20:1. For example, the aspect ratio can be 16:1, 17:1, 18:1, 19:1, or 20:1. Of course, the aspect ratio of the second trenches 102 can also be other ratios, which will not be listed one by one here. In some embodiments of the present disclosure, there is a first trench 101 filled with the first filling layer 21 between any two adjacent second trenches 102 among the plurality of second trenches 102. Some of the first trenches 101 can be etched by an anisotropic etching (for example, dry etching) process to form the second trenches 102. In some embodiments of the present disclosure, the cross-sectional structure cut along the aa' direction in Figure 2 or along the bb' direction in Figure 3 after step S140 is completed is as shown in Figure 8 ; the cross-sectional structure cut along the cc' direction in Figure 3 after step S140 is completed is as shown in Figure 9 .

[0115] In an exemplary embodiment of the present disclosure, etching some of the first trenches 101 to form a plurality of second trenches 102, and having a first trench filled with the first filling layer 21 between any two adjacent second trenches 102 (i.e., step S140) can include step S210 and step S220, where:

[0116] Step S210: Form a first mask layer 31 on the side of the first filling layer 21 away from the substrate 1. The first mask layer 31 includes a plurality of first mask regions 314 distributed at intervals and first etching regions 315 located on opposite sides of the first mask regions 314. The orthographic projection of the first etching regions 315 on the substrate 1 coincides with the orthographic projection of some of the first trenches 101 on the substrate 1, and the orthographic projection of the first mask regions 314 on the substrate 1 covers the orthographic projection of the remaining first trenches 101 on the substrate 1.

[0117] As Figure 10 and Figure 11 shown, the first mask layer 31 can be formed on the first filling layer 21 by means such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, and / or spin coating. Of course, the first mask layer 31 can also be formed by other means, and no special limitation is imposed on the formation method of the first mask layer 31 herein. In some embodiments of the present disclosure, the first mask layer 31 may include a plurality of first mask regions 314 distributed at intervals. The first mask regions 314 may be strip-shaped, and the two side edges of the strip-shaped first mask regions 314 are parallel and oppositely arranged. The regions adjacent to the two side edges of each first mask region 314 are both first etching regions 315.

[0118] In some embodiments of the present disclosure, the orthographic projections of the respective first etching regions 315 on the substrate 1 respectively coincide with the orthographic projections of different first trenches 101 on the substrate 1; at the same time, the orthographic projections of the respective first mask regions 314 on the substrate 1 cover the orthographic projections of the remaining first trenches 101 (i.e., the first trenches 101 whose orthographic projections on the substrate 1 do not coincide or overlap with the orthographic projections of the first etching regions 315 on the substrate 1) on the substrate 1. For example, the first mask regions 314 may cover the regions in the first filling layer 21 that are not covered by the first etching regions 315.

[0119] In some embodiments of the present disclosure, the respective first etching regions 315 and the respective first mask regions 314 may be alternately distributed, and there is a first mask region 314 between two adjacent first etching regions 315, or there is a first etching region 315 between two adjacent first mask regions 314.

[0120] In an exemplary embodiment of the present disclosure, forming the first mask layer 31 (i.e., step S210) on the side of the first filling layer 21 away from the substrate 1 may include steps S310 - S340, where:

[0121] Step S310: Form a first mask material layer 311 on the side of the first filling layer 21 away from the substrate 1.

[0122] As Figure 12 and Figure 13As shown, the first mask material layer 311 can be a composite film layer composed of a multi-layer film structure or a single-layer film structure, and no special limitation is made here. Taking the first mask material layer 311 as a composite film layer as an example, the first mask material layer 311 may include a first sub-film layer 301, a second sub-film layer 302, a third sub-film layer 303, and a fourth sub-film layer 304 that are sequentially stacked from bottom to top in a direction perpendicular to the substrate 1. Among them, the material of the first sub-film layer 301 can be carbon, the material of the second sub-film layer 302 can be silicon oxynitride, the material of the third sub-film layer 303 can be a spin-on hard mask, and the material of the fourth sub-film layer 304 can be silicon oxynitride. The first sub-film layer 301 and the second sub-film layer 302 can be sequentially formed on the first filling layer 21 by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, etc. Subsequently, the third sub-film layer 303 can be formed on the second sub-film layer 302 by spin coating, etc. Finally, the fourth sub-film layer 304 can be formed on the third sub-film layer 303 by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, etc.

[0123] Step S320: Etch the first mask material layer 311 to form a plurality of first mask structures 3111 distributed at intervals.

[0124] Please continue to refer to Figure 12 and Figure 13 As shown, a first photoresist layer 51 can be formed on the surface of the fourth sub-film layer 304 away from the substrate 1. The first photoresist layer 51 can be exposed and developed, and using the remaining first photoresist layer 51 as a mask, the fourth sub-film layer 304 and the third sub-film layer 303 in the first mask material layer 311 are etched, thereby forming a plurality of first mask structures 3111 distributed at intervals along the first direction x (as shown in Figure 14 and Figure 15 shown).

[0125] It should be noted that after the first mask structure 3111 is formed, the first photoresist layer 51 can be removed, and the first mask structure 3111 can be cleaned to remove the residual etching gas and residual by-products.

[0126] Step S330: Form a first etching material layer 312 on the sidewalls of the first mask structure 3111 to serve as the first etching region 315.

[0127] Please continue to refer to Figure 14 and Figure 15As shown, the material of the first etching material layer 312 is different from that of the first sub-film layer 301, the second sub-film layer 302, the third sub-film layer 303, and the fourth sub-film layer 304. For example, the material of the first etching material layer 312 can be silicon oxide. The first etching material layer 312 can be formed on the sidewalls of the first mask structure 3111 by chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc. During this process, for the convenience of the process, the first etching material layer 312 can be formed simultaneously on the top surface exposed in the second sub-film layer 302 and the top surface of the first mask structure 3111.

[0128] Step S340, fill the first filling material 313 between the structure jointly formed by the first mask structure 3111 and the first etching region 315 to form a plurality of second mask structures 3131 distributed at intervals. The first mask structure 3111 and the second mask structure 3131 jointly form the first mask region 314.

[0129] As Figure 16 and Figure 17 shown, the first filling material 313 can be formed on the side of the first etching material layer 312 away from the substrate 1 until the gaps between adjacent first mask structures 3111 are filled with the first filling material 313. In some embodiments of the present disclosure, the first filling material 313 can be etched back so that the top surface of the first filling material 313 is flush with the top surface of the first mask structure 3111. It should be noted that when the top of the first mask structure 3111 is covered with the first etching material layer 312, the first etching material layer 312 can also be etched after etching back the first filling material 313, thereby removing the first etching material layer 312 located on the top of the first mask structure 3111 and making the top of the remaining first etching material layer 312 flush with the top surface of the first mask structure 3111 (as Figure 10 and Figure 11 shown). In some other embodiments of the present disclosure, after forming the first filling material 313, chemical mechanical polishing can be performed on the first filling material 313 and the first etching material layer 312 except for the first etching material layer 312 located on the top of the first mask structure 3111, so that the top of the first filling material 313 and the top of the first etching material layer 312 are both flush with the top surface of the first mask structure 3111. The remaining first filling material 313 can be used as the second mask structure 3131, and the remaining first etching material layer 312 can be used as the first etching region 315.

[0130] Step S220, use the first mask region 314 as a mask to etch the first etching region 315, the first filling layer 21 located directly below the first etching region 315, and the first trench 101 located directly below the first etching region 315 to form a second trench 102 in the substrate 1.

[0131] A dry etching process can be employed to etch each first etching region 315, the first filling layer 21 located directly below each first etching region 315, and the first trench 101 located directly below each first etching region 315, using the first mask region 314 as a mask, thereby forming a plurality of second trenches 102. It should be noted that, among the plurality of second trenches 102, a first trench 101 filled with the first filling layer 21 is provided between any two adjacent second trenches 102.

[0132] In some embodiments of the present disclosure, the depth of the second trench 102 can be 1.5 to 2.2 times the depth of the first trench 101. For example, the depth of the second trench 102 is 1.5 times, 1.7 times, 1.9 times, 2.1 times, or 2.2 times the depth of the first trench 101.

[0133] As Figure 1 shown, in step S150, a second filling layer 22 is formed, and the second filling layer 22 fills the second trench 102.

[0134] In an exemplary embodiment of the present disclosure, before forming the second filling layer 22, the remaining first mask layer 31 can be removed by etching, chemical mechanical polishing, or the like, thereby exposing the surface of the remaining first filling layer 21 (as Figure 8 and Figure 9 shown).

[0135] The material of the second filling layer 22 can be an insulating material. For example, the material of the second filling layer 22 can include silicon oxide and / or silicon nitride. As Figure 18 and Figure 19 shown, an insulating material can be deposited on the surface of the structure jointly formed by the first filling layer 21 and the second trench 102 by chemical vapor deposition, physical vapor deposition, atomic layer deposition, or the like, thereby forming the second filling layer 22. During this process, the insulating material can fill the second trench 102. Chemical mechanical polishing can be performed on the insulating material to make its surface flat, and the remaining insulating material can be used as the second filling layer 22.

[0136] In an exemplary embodiment of the present disclosure, before forming the second filling layer 22, the second trench 102 can be cleaned to remove residues, which helps to improve the device reliability. After cleaning the second trench 102, the second filling layer 22 formed in the second trench 102 can be used as a trench isolation structure. That is, in the process of forming the active region 114 in the present disclosure, a trench isolation structure can be formed simultaneously, so that it is not necessary to form a trench isolation structure through a separate process subsequently, which can simplify the process and reduce costs.

[0137] It should be noted that since there are first grooves 101 filled with the first filling layer 21 between adjacent second grooves 102, during the cleaning process of the second grooves 102, the first filling layer 21 can support at least one side of the remaining substrate 1 in the second grooves 102 (i.e., the side walls of the second grooves 102), which can reduce the probability of the side walls of the second grooves 102 collapsing due to capillary force during the cleaning process of the second grooves 102, and contribute to improving the product yield.

[0138] As Figure 1 shown, in step S160, the remaining first grooves 101 are etched to form third grooves 103, and there are second grooves 102 filled with the second filling layer 22 between any two adjacent third grooves 103.

[0139] As Figure 20 shown, the aspect ratio of the third grooves 103 can be the same as that of the second grooves 102. For example, the aspect ratio of the third grooves 103 can be 16:1 to 20:1. For example, the aspect ratio can be 16:1, 17:1, 18:1, 19:1 or 20:1. Of course, the aspect ratio of the third grooves 103 can also be other ratios, which will not be listed one by one here. In some embodiments of the present disclosure, there is a second groove 102 filled with the second filling layer 22 between any two adjacent third grooves 103 among the plurality of third grooves 103. The remaining first grooves 101 can be etched by an anisotropic etching process (such as dry etching) to form the third grooves 103.

[0140] In an exemplary embodiment of the present disclosure, etching the remaining first grooves 101 to form third grooves 103, and having second grooves 102 filled with the second filling layer 22 between any two adjacent third grooves 103 (i.e., step S160) may include step S410 and step S420, where:

[0141] Step S410, forming a second mask layer 32 on the side of the second filling layer 22 away from the substrate 1. The second mask layer 32 includes a plurality of second mask regions 324 distributed at intervals and second etching regions 325 located on opposite sides of the second mask regions 324. The orthographic projection of the second etching regions 325 on the substrate 1 coincides with the orthographic projection of the remaining first grooves 101 on the substrate 1, and the orthographic projection of the second mask regions 324 on the substrate 1 covers the orthographic projection of the second grooves 102 on the substrate 1.

[0142] As Figure 21 and Figure 22As shown, the second mask layer 32 may be formed on the second filling layer 22 by means of chemical vapor deposition, physical vapor deposition, atomic layer deposition, and / or spin coating. Of course, the second mask layer 32 may also be formed by other means, and the formation method of the second mask layer 32 is not specifically limited herein. In some embodiments of the present disclosure, the second mask layer 32 may include a plurality of second mask regions 324 distributed at intervals. The second mask regions 324 may be strip-shaped. The two side edges of the strip-shaped second mask region 324 are parallel and oppositely arranged, and the regions adjacent to the two side edges of each second mask region 324 are second etching regions 325.

[0143] In some embodiments of the present disclosure, the orthographic projections of the second etching regions 325 on the substrate 1 respectively coincide with the orthographic projections of different first trenches 101 in the remaining first trenches 101 on the substrate 1; at the same time, the orthographic projections of the second mask regions 324 on the substrate 1 respectively cover the orthographic projections of different second trenches 102 on the substrate 1. For example, the second mask region 324 may cover the region in the second filling layer 22 that is not covered by the second etching region 325.

[0144] In some embodiments of the present disclosure, the second etching regions 325 and the second mask regions 324 may be alternately distributed, and a second mask region 324 is provided between two adjacent second etching regions 325, or a second etching region 325 is provided between two adjacent second mask regions 324. That is, before etching the remaining first trenches 101, a first trench 101 is provided between any two adjacent second trenches 102 among the plurality of second trenches 102.

[0145] In an exemplary embodiment of the present disclosure, forming the second mask layer 32 on the side of the second filling layer 22 away from the substrate 1 (i.e., step S410) may include steps S510 - S540, where:

[0146] Step S510, forming a second mask material layer 321 on the side of the second filling layer 22 away from the substrate 1.

[0147] Such as Figure 23 And Figure 24As shown, the second mask material layer 321 can be a composite film layer composed of a multi-layer film structure or a single-layer film structure, and no special limitation is made here. In some embodiments of the present disclosure, the structure of the second mask material layer 321 is the same as that of the first mask material layer 311. For example, the second mask material layer 321 may also include a first sub-layer 301, a second sub-layer 302, a third sub-layer 303, and a fourth sub-layer 304 that are sequentially stacked from bottom to top in a direction perpendicular to the substrate 1. Among them, the material of the first sub-layer 301 can be carbon, the material of the second sub-layer 302 can be silicon oxynitride, the material of the third sub-layer 303 can be a spin-on hard mask, and the material of the fourth sub-layer 304 can be silicon oxynitride. The first sub-layer 301 and the second sub-layer 302 can be sequentially formed on the second filling layer 22 by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, etc. Subsequently, the third sub-layer 303 can be formed on the second sub-layer 302 by spin coating, etc. Finally, the fourth sub-layer 304 can be formed on the third sub-layer 303 by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, etc.

[0148] Step S520: Etch the second mask material layer 321 to form a plurality of third mask structures 3211 distributed at intervals.

[0149] Please continue to refer to Figure 23 and Figure 24 As shown, a second photoresist layer 52 can be formed on the surface of the fourth sub-layer 304 away from the substrate 1. The second photoresist layer 52 can be exposed and developed, and the fourth sub-layer 304 and the third sub-layer 303 in the second mask material layer 321 are etched with the remaining second photoresist layer 52 as a mask, thereby forming a plurality of third mask structures 3211 distributed at intervals along the first direction x, as Figure 25 shown.

[0150] It should be noted that after the third mask structure 3211 is formed, the second photoresist layer 52 can be removed, and the third mask structure 3211 can be cleaned to remove the residual etching gas and residual by-products.

[0151] Step S530: Form a second etching material layer 322 on the sidewalls of the third mask structure 3211 to serve as the second etching region 325.

[0152] The material of the second etching material layer 322 is different from the materials of the first sub-layer 301, the second sub-layer 302, the third sub-layer 303, and the fourth sub-layer 304 in the second mask material layer 321. For example, the material of the second etching material layer 322 can be silicon oxide. As Figure 26As shown, the second etching material layer 322 can be formed on the sidewalls of the third mask structure 3211 by means of chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc. During this process, for the convenience of the process, the second etching material layer 322 can be simultaneously formed on the top surface exposed in the second sub-layer 302 of the second mask material layer 321 and on the top surface of the third mask structure 3211.

[0153] In step S540, the second filling material 323 is filled between the structure jointly formed by the third mask structure 3211 and the second etching region 325 to form a plurality of fourth mask structures 3231 distributed at intervals. The third mask structure 3211 and the fourth mask structures 3231 jointly constitute the second mask region 324.

[0154] Please continue to refer to Figure 26As shown, a second filling material 323 may be deposited on a side of the second etching material layer 322 away from the substrate 1 until the second filling material 323 fills the gaps between adjacent third mask structures 3211. In some embodiments of the present disclosure, the second filling material 323 may be etched back to make the top surface of the second filling material 323 flush with the top surface of the third mask structure 3211. It should be noted that when the top of the third mask structure 3211 is covered with the second etching material layer 322, the second etching material layer 322 may be etched after etching back the second filling material 323, so as to remove the second etching material layer 322 located on the top of the third mask structure 3211 and make the top of the remaining second etching material layer 322 flush with the top surface of the third mask structure 3211. In some other embodiments of the present disclosure, after the second filling material 323 is formed, chemical mechanical polishing may be performed on the second filling material 323 and the second etching material layer 322 except for the second etching material layer 322 located on the top of the third mask structure 3211, so that the top of the second filling material 323 and the top of the second etching material layer 322 are both flush with the top surface of the third mask structure 3211. The remaining second filling material 323 may be used as a fourth mask structure 3231, and the remaining second etching material layer 322 may be used as a second etching region 325. It should be noted that since the cc' cross-section direction is always covered by the second photoresist layer 52 during the formation of the third mask structure 3211 and the fourth mask structure 3231, the structure of the second mask material layer 321 in the cc' cross-section direction is not damaged, and the subsequently formed second etching material layer 322 and second filling material 323 are sequentially laid on the second mask material layer 321. During the etching back (or polishing) of the second filling material 323 and the second mask material layer 321, for the cc' cross-section direction, only the second etching material layer 322 and the second filling material 323 on the top of the second mask material layer 321 are removed. Therefore, the structure of the second mask layer 32 finally formed in the cc' cross-section direction is the same as the structure of the second mask material layer 321, as specifically shown in Figure 22 shown.

[0155] Step S420: Using the second mask region 324 as a mask, etch the second etching region 325, the first filling layer 21 located directly below the second etching region 325, and the first trench 101 located directly below the second etching region 325 to form a third trench 103 in the substrate 1.

[0156] A dry etching process can be adopted to etch each second etching region 325, the first filling layer 21 located directly below each second etching region 325, and the first trench 101 located directly below each second etching region 325 with the second mask region 324 as a mask, thereby forming a plurality of third trenches 103. It should be noted that, among the plurality of third trenches 103, a second trench 102 filled with the second filling layer 22 is provided between any two adjacent third trenches 103.

[0157] In some embodiments of the present disclosure, the depth of the third trench 103 can be 1.5 to 2.2 times the depth of the first trench 101. For example, the depth of the third trench 103 is 1.5 times, 1.7 times, 1.9 times, 2.1 times, or 2.2 times the depth of the first trench 101.

[0158] As Figure 1 shown, in step S170, a third filling layer 23 is formed, and the third filling layer 23 fills the third trench 103.

[0159] In an exemplary embodiment of the present disclosure, before forming the third filling layer 23, the second mask layer 32 can be removed, thereby exposing the surface of the remaining second filling layer 22. Before forming the third filling layer 23, the third trench 103 can also be cleaned to remove impurities, which helps to improve the product reliability. During the process of cleaning the third trench 103, since there is a second trench 102 filled with the second filling layer 22 between any two adjacent third trenches 103, during the process of cleaning the third trench 103, the second filling layer 22 can be used to support at least one side of the remaining substrate 1 in the third trench 103 (i.e., the side wall of the third trench 103), reducing the probability of the side wall of the third trench 103 collapsing due to the capillary force during the process of cleaning the third trench 103. That is, the present application can reduce the collapse probability of the active region 114 defined by the second trench 102 and the third trench 103 and improve the product yield. In addition, the third filling layer 23 can directly serve as a trench isolation structure between the active regions 114. That is, the design of the third filling layer 23 can not only reduce the collapse probability of the active region 114, but also form a trench isolation structure simultaneously during the process of forming the active region 114, eliminating the need for a separate process to form the trench isolation structure subsequently, simplifying the process and reducing costs.

[0160] The material of the third filling layer 23 may be the same as that of the second filling layer 22. For example, the material of the third filling layer 23 may be an insulating material. For example, the material of the third filling layer 23 may include silicon oxide and / or silicon nitride. The insulating material may be deposited on the surface of the structure formed by the second filling layer 22 and the third trench 103 by means of chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc., so as to form the third filling layer 23. In this process, the insulating material may fill the third trench 103. The insulating material may be subjected to chemical mechanical polishing to make its surface flat, and the remaining insulating material may be used as the third filling layer 23. In the embodiment of the present disclosure, after step S170 is completed, along Figure 2 the aa' direction in Figure 3 or along the bb' direction in Figure 27 the cross-sectional structure shown is

[0161] In an exemplary embodiment of the present disclosure, please continue to refer to Figure 2 and Figure 3 shown. The first gap 112 between two adjacent first trenches 101 and / or the second gap 113 between two adjacent first trenches 101 may be used as a connection area. In the first direction x, each connection area and each first trench 101 are alternately distributed in sequence, and the first filling layer 21 also fills the connection area.

[0162] The method for forming the semiconductor structure of the present disclosure further includes step S180 and step S190, wherein:

[0163] Step S180, after forming the third filling layer 23, etch the first filling layer 21 located in the connection area and the connection area to increase the depth of the connection area in the substrate 1.

[0164] The connection area and the first filling layer 21 filled in the connection area may be etched by a dry etching process, so as to increase the depth of the connection area. The depth of the connection area may be substantially the same as the depth of the second trench 102 or the third trench 103, or the depth of the connection area may be slightly greater than the depth of the first trench 101 or the third trench 103, and no special limitation is made here.

[0165] In an exemplary embodiment of the present disclosure, after forming the third filling layer 23, etching the first filling layer 21 located in the connection area and the connection area to increase the depth of the connection area in the substrate 1 (i.e., step S180) may include step S610-step S630, wherein:

[0166] Step S610, form a third mask layer 33 on the side of the first filling layer 21, the second filling layer 22, and the third filling layer 23 away from the substrate 1.

[0167] As Figure 28As shown, the third mask layer 33 may be a single-layer film structure or a composite film structure composed of multiple film layers, and no special limitation is made here. For example, the third mask layer 33 may include a fifth sub-layer 305 and a sixth sub-layer 306. Among them, the material of the fifth sub-layer 305 may be a spin-on hard mask, and the material of the sixth sub-layer 306 may be silicon oxynitride. The fifth sub-layer 305 can be formed by processes such as spin coating, and the sixth sub-layer 306 can be formed by chemical vapor deposition, physical vapor deposition, atomic layer deposition, or the like.

[0168] Step S620: Form a photoresist layer 4 on the side of the third mask layer 33 away from the substrate 1. The photoresist layer 4 includes a plurality of developing regions 41, and the orthographic projections of the respective developing regions 41 on the substrate 1 respectively coincide with the orthographic projections of the respective connection regions on the substrate 1.

[0169] Please continue to refer to Figure 28 As shown, the photoresist layer 4 can be formed on the third mask layer 33 by means such as spin coating. The material of the photoresist layer 4 may be a photoresist. For example, it may be a positive photoresist or a negative photoresist, and no special limitation is made here. The photoresist layer 4 can be exposed and developed to form a plurality of developing regions 41, and the orthographic projections of the respective developing regions 41 on the substrate 1 respectively coincide with the orthographic projections of different connection regions on the substrate 1.

[0170] Step S630: Etch the first filling layer 21 and the connection region 115 directly below the first filling layer 21 in the developing region 41 to increase the depth of the connection region 115 in the substrate 1.

[0171] As Figure 29 As shown, using the remaining photoresist layer 4 after development as a mask, etch the third mask layer 33, the first filling layer 21 located below the third mask layer 33, and the connection region 115 directly below the first filling layer 21 in the developing region 41 to increase the depth of the connection region 115 in the substrate 1.

[0172] Step S190: Form a fourth filling layer 24, and the fourth filling layer 24 fills the connection region 115 with an increased depth.

[0173] In an exemplary embodiment of the present disclosure, as Figure 30As shown, after increasing the depth of the connection region 115, the connection region 115 can also be cleaned. During this process, the remaining substrate 1 around the connection region 115 can be supported by the second filling layer 22 and the third filling layer 23, which can effectively reduce the collapse probability of the remaining substrate 1 around during the cleaning of the connection region 115. The material of the fourth filling layer 24 can be the same as that of the second filling layer 22 or the third filling layer 23. For example, the material of the fourth filling layer 24 can include silicon oxide and / or silicon nitride. The fourth filling layer 24 can fill the connection region 115 with increased depth. The second trench 102, the third trench 103, and the connection region 115 with increased depth can jointly divide the substrate 1 into multiple active regions 114 distributed at intervals; the fourth filling layer 24, the second filling layer 22, and the third filling layer 23 can jointly form a shallow trench isolation structure (Shallow Trench Isolation, abbreviated as STI) that fills the gaps between the active regions 114.

[0174] In the process of forming the active region 114 in the present disclosure, a shallow trench isolation structure for isolating the active regions 114 is formed simultaneously, so that it is not necessary to form a trench isolation structure through a separate process subsequently, which can simplify the process and reduce costs. And during the manufacturing process, different regions of the shallow trench isolation structure are used to support other regions, which can prevent the active region 114 from collapsing due to the surface tension or capillary force of the liquid during the cleaning process. Compared with the prior art, in the process of cleaning the second trench 102, the third trench 103, and the connection region 115 in the present disclosure, only a conventional cleaning solution needs to be used, and there is no need to specifically add various surfactants to the cleaning solution to reduce the surface tension or capillary force, which helps to reduce the residue of the surfactant and improve the product yield. At the same time, the present disclosure also does not need to use the supercritical fluid drying method to reduce or eliminate the surface tension or capillary force of the cleaning solution, has low requirements for equipment, and low manufacturing costs.

[0175] It should be noted that although the steps of the method for forming the semiconductor structure in the present disclosure are described in a specific order in the drawings, this does not require or imply that these steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired result. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution, etc.

[0176] The present disclosure also provides a semiconductor structure, which is formed by the method for forming a semiconductor structure in any of the above embodiments. For example, the semiconductor structure includes a plurality of active regions 114 divided by a second trench 102, a third trench 103, and a plurality of connection regions 115 connecting between the second trench 102 and the third trench 103. Filling layers are provided in the second trench 102, the third trench 103, and the connection regions 115; the active region 114 includes a first sidewall and a second sidewall facing each other, the surfaces of the first sidewall and the second sidewall are both flat, the first sidewall and the second sidewall may be parallel to each other, and both the first sidewall and the second sidewall extend in a direction perpendicular to the bottom surface of the substrate 1.

[0177] In some embodiments of the present disclosure, the second trench 102 and the third trench 103 may be alternately distributed in sequence along the first direction x, and there is one third trench 103 between two adjacent second trenches 102, or there is one second trench 102 between two adjacent third trenches 103. The adjacent second trench 102 and third trench 103 can be connected through a plurality of connection regions 115.

[0178] In some embodiments of the present disclosure, the aspect ratio of the second trench 102 is 16:1 to 20:1; for example, the aspect ratio can be 16:1, 17:1, 18:1, 19:1, or 20:1. Of course, the aspect ratio of the second trench 102 can also be other ratios, which will not be listed one by one here. The aspect ratio of the third trench 103 can be the same as that of the second trench 102. For example, the aspect ratio of the third trench 103 is 16:1 to 20:1. For example, the aspect ratios of both the third trench 103 and the second trench 102 can be 16:1, 17:1, 18:1, 19:1, or 20:1.

[0179] Other details and beneficial effects of the semiconductor structure of the present disclosure have been described in detail in the embodiments of the corresponding method for forming a semiconductor structure. Therefore, they will not be repeated here.

[0180] Those skilled in the art will readily think of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A method for forming a semiconductor structure, characterized in that, Comprising: Providing a substrate; Etching the substrate to form a plurality of first trenches distributed at intervals, the aspect ratio of the first trenches being 10:1 to 8:1; Forming a first filling layer, the first filling layer filling the first trenches and covering the surface of the etched substrate; Etching a part of the first trenches to form a plurality of second trenches, with the first trenches filled with the first filling layer between every two adjacent second trenches, the aspect ratio of the second trenches being 16:1 to 20:1; Forming a second filling layer, the second filling layer filling the second trenches; Etching the remaining first trenches to form third trenches, with the second trenches filled with the second filling layer between every two adjacent third trenches; Forming a third filling layer, the third filling layer filling the third trenches, the aspect ratio of the third trenches being 16:1 to 20:

1.

2. The forming method according to claim 1, wherein, The etching of a part of the first trenches to form a plurality of second trenches, with the first trenches filled with the first filling layer between every two adjacent second trenches, includes: Forming a first mask layer on the side of the first filling layer away from the substrate, the first mask layer including a plurality of first mask regions distributed at intervals and first etching regions on opposite sides of the first mask regions, the orthographic projection of the first etching regions on the substrate coinciding with the orthographic projection of a part of the first trenches on the substrate, and the orthographic projection of the first mask regions on the substrate covering the orthographic projection of the remaining first trenches on the substrate; Using the first mask regions as a mask to etch the first etching regions, the first filling layer located directly below the first etching regions, and the first trenches located directly below the first etching regions, to form the second trenches in the substrate.

3. The forming method according to claim 2, wherein The forming method further includes: Removing the remaining first mask layer before forming the second filling layer; The forming of the second filling layer, the second filling layer filling the second trenches, includes: Forming a second filling layer on the surface of the structure jointly constituted by the first filling layer and the second trenches, the second filling layer filling the second trenches.

4. The forming method according to claim 3, characterized in that, The etching of the remaining first trenches to form third trenches, with the second trenches filled with the second filling layer between every two adjacent third trenches, includes: Forming a second mask layer on the side of the second filling layer away from the substrate, the second mask layer including a plurality of second mask regions distributed at intervals and second etching regions on opposite sides of the second mask regions, the orthographic projection of the second etching regions on the substrate coinciding with the orthographic projection of the remaining first trenches on the substrate, and the orthographic projection of the second mask regions on the substrate covering the orthographic projection of the second trenches on the substrate; Using the second mask regions as a mask to etch the second etching regions, the first filling layer located directly below the second etching regions, and the first trenches located directly below the second etching regions, to form the third trenches in the substrate.

5. The forming method according to claim 1, wherein Before etching the remaining first trenches, one first trench is provided between any two adjacent second trenches among the plurality of second trenches.

6. The forming method according to claim 1, wherein Etching the substrate to form a plurality of first trenches spaced apart from each other, including: Etching the substrate to form a plurality of initial active groups spaced apart in a first direction, with a first trench between adjacent initial active groups; each initial active group includes a plurality of initial active regions spaced apart in a second direction; based on the initial active regions, two adjacent initial active groups are aligned, and two adjacent first trenches communicate through a first gap between two adjacent initial active regions distributed in the second direction; each first trench and each first gap define the initial active regions as columnar structures, and the second direction is perpendicular to the first direction.

7. The forming method according to claim 1, characterized in that, Etching the substrate to form a plurality of first trenches spaced apart from each other, including: Etching the substrate to form a plurality of initial active groups spaced apart in a first direction, with a first trench between adjacent initial active groups; each initial active group includes a plurality of initial active regions extending in a second direction and spaced apart in the second direction; based on the initial active regions, two adjacent initial active groups are staggeredly distributed, and two adjacent first trenches communicate through a second gap between two adjacent initial active regions distributed in the second direction; the second direction intersects the first direction.

8. The forming method according to claim 7, characterized in that, Using the second gap as a connection region, the connection region and the first trenches are alternately distributed in sequence; the first filling layer also fills the connection region; The forming method further includes: After forming the third filling layer, etching the first filling layer and the connection region located in the connection region to increase the depth of the connection region in the substrate; Forming a fourth filling layer, and the fourth filling layer fills the connection region with an increased depth.

9. The forming method according to claim 8, wherein The etching the first filling layer and the connection region located in the connection region to increase the depth of the connection region in the substrate after forming the third filling layer, includes: Forming a third mask layer on a side of the first filling layer, the second filling layer, and the third filling layer away from the substrate; Forming a photoresist layer on a side of the third mask layer away from the substrate, the photoresist layer includes a plurality of developing regions, and the orthographic projections of the developing regions on the substrate respectively coincide with the orthographic projections of the connection regions on the substrate; Etching the first filling layer and the connection region directly below the first filling layer in the developing regions to increase the depth of the connection region in the substrate.

10. The forming method according to claim 2, characterized in that, The forming the first mask layer on a side of the first filling layer away from the substrate, includes: Forming a first mask material layer on a side of the first filling layer away from the substrate; Etching the first mask material layer to form a plurality of first mask structures spaced apart from each other; Forming a first etching material layer on sidewalls of the first mask structures to serve as the first etching regions; A first filling material is filled between the structures jointly formed by the first mask structure and the first etching region to form a plurality of second mask structures distributed at intervals, and the first mask structure and the second mask structure jointly form the first mask region.

11. The forming method according to claim 4, wherein, Forming a second mask layer on a side of the second filling layer away from the substrate includes: Forming a second mask material layer on a side of the second filling layer away from the substrate; Etching the second mask material layer to form a plurality of third mask structures distributed at intervals; Forming a second etching material layer on sidewalls of the third mask structure to serve as the second etching region; A second filling material is filled between the structures jointly formed by the third mask structure and the second etching region to form a plurality of fourth mask structures distributed at intervals, and the third mask structure and the fourth mask structure jointly form the second mask region.

12. The forming method according to claim 1, characterized in that, The forming method further includes: Cleaning the second trench before forming the second filling layer; Cleaning the third trench before forming the third filling layer.

13. A semiconductor structure, characterized in that, The semiconductor structure is formed by the forming method of the semiconductor structure according to any one of claims 1-12. The semiconductor structure includes a plurality of active regions divided by the second trench, the third trench, and a plurality of connection regions connecting between the second trench and the third trench. Filling layers are provided in the second trench, the third trench, and the connection regions. The active region includes a first sidewall and a second sidewall that are oppositely disposed. The first sidewall and the second sidewall are parallel to each other and both extend in a direction perpendicular to the bottom surface of the substrate. The aspect ratio of the second trench is 16:1 to 20:1, and the aspect ratio of the third trench is 16:1 to 20:1.

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