Semiconductor structure and forming method thereof

Abstract

The invention relates to the technical field of semiconductors, and relates to a semiconductor structure and a forming method thereof, and the forming method comprises the steps: providing a substrate; etching the substrate to form a plurality of first grooves which are distributed at intervals; forming a first filling layer, wherein the first filling layer fills the first groove and covers the surface of the etched substrate; part of the first grooves are etched to form a plurality of second grooves, and the first grooves filled with the first filling layers are arranged between every two adjacent second grooves; forming a second filling layer, wherein the second filling layer fills the second groove; the remaining first grooves are etched to form third grooves, and a second groove filled with a second filling layer is formed between every two adjacent third grooves; and forming a third filling layer, wherein the third filling layer fills the third groove. According to the forming method, the probability of collapse of the active region can be obviously reduced, and the product yield is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular, 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 tablets due to its advantages such as small size, high integration and fast transmission speed. The active area is one of the important components of memory and plays a vital role in the performance of the device. However, as the size of the device continues to shrink, the active area is easily affected by the formation process during the manufacturing process, and structural defects such as collapse are prone to occur, resulting in low product yield.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. 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 of the active region and improve product yield.

[0005] According to one aspect of the present disclosure, a method for forming a semiconductor structure is provided, comprising: providing a substrate; Etching the substrate to form a plurality of first grooves distributed at intervals; forming a first filling layer, wherein the first filling layer fills the first trench and covers the surface of the etched substrate; Etching part of the first trenches to form a plurality of second trenches, wherein each of two adjacent second trenches has the first trench filled with the first filling layer; forming a second filling layer, wherein the second filling layer fills the second trench; Etching the remaining first trenches to form third trenches, wherein the second trench filled with the second filling layer is provided between two adjacent third trenches; A third filling layer is formed, wherein the third filling layer fills the third trench.

[0006] In an exemplary embodiment of the present disclosure, etching a portion of the first trenches to form a plurality of second trenches, wherein each of two adjacent second trenches has a first trench filled with the first filling layer, including: forming a first mask layer on a side of the first filling layer away from the substrate, the first mask layer comprising a plurality of first mask areas distributed at intervals and first etching areas located on opposite sides of the first mask areas, the orthographic projections of the first etching areas on the substrate coincide with the orthographic projections of a portion of the first grooves on the substrate, and the orthographic projections of the first mask areas on the substrate cover the orthographic projections of the remaining first grooves on the substrate; The first etching region, the first filling layer directly below the first etching region, and the first trench directly below the first etching region are etched using the first mask region as a mask to form the second trench in the substrate.

[0007] In an exemplary embodiment of the present disclosure, the forming method further includes: Before forming the second filling layer, removing the remaining first mask layer; The forming of a second filling layer, wherein the second filling layer fills the second trench, comprises: A second filling layer is formed on the surface of the structure formed by the first filling layer and the second groove, and the second filling layer fills the second groove.

[0008] In an exemplary embodiment of the present disclosure, etching the remaining first trenches to form third trenches, wherein the second trenches filled with the second filling layer are provided between two adjacent third trenches, comprises: forming a second mask layer on a side of the second filling layer away from the substrate, the second mask layer comprising a plurality of second mask areas distributed at intervals and second etching areas located on opposite sides of the second mask areas, the orthographic projections of the second etching areas on the substrate coincide with the orthographic projections of the remaining first grooves on the substrate, and the orthographic projections of the second mask areas on the substrate cover the orthographic projections of the second grooves on the substrate; The second etching region, the first filling layer directly below the second etching region, and the first trench directly below the second etching region are etched using the second mask region as a mask to form the third trench in the substrate.

[0009] In an exemplary embodiment of the present disclosure, before etching the remaining first trenches, one first trench is provided between any two adjacent second trenches among the plurality of second trenches.

[0010] In an exemplary embodiment of the present disclosure, etching the substrate to form a plurality of first trenches distributed at intervals includes: The substrate is etched to form a plurality of initial active groups spaced apart along a first direction, wherein the first grooves are disposed between adjacent initial active groups; each initial active group includes a plurality of initial active regions spaced apart along a second direction; two adjacent initial active groups are aligned with each other based on the initial active regions, and two adjacent first grooves are connected via a first gap between two adjacent initial active regions distributed along the second direction; each of the first grooves and each of the first gaps defines the initial active region as a columnar structure, and the second direction is perpendicular to the first direction.

[0011] In an exemplary embodiment of the present disclosure, etching the substrate to form a plurality of first trenches distributed at intervals includes: The substrate is etched to form a plurality of initial active groups spaced apart along a first direction, with the first grooves being between adjacent initial active groups; each initial active group includes a plurality of initial active regions extending along a second direction and spaced apart along the second direction; two adjacent initial active groups are staggered with respect to the initial active regions, and two adjacent first grooves are connected via a second gap between two adjacent initial active regions spaced apart along the second direction; and the second direction intersects with the first direction.

[0012] In an exemplary embodiment of the present disclosure, the second gap is used as a connection area, and the connection area and the first groove are alternately distributed in sequence; the first filling layer also fills the connection area; The forming method further comprises: After forming the third filling layer, etching the first filling layer and the connection area in the connection area to increase the depth of the connection area in the substrate; A fourth filling layer is formed, wherein the fourth filling layer fills the connection area with an increased depth.

[0013] In an exemplary embodiment of the present disclosure, after forming the third filling layer, etching the first filling layer and the connection area in the connection area to increase the depth of the connection area in the substrate 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, wherein the photoresist layer comprises a plurality of developing areas, and the orthographic projections of the developing areas on the substrate respectively coincide with the orthographic projections of the connecting areas on the substrate; The first filling layer and the connection region directly below the first filling layer are etched in the development region to increase the depth of the connection region in the substrate.

[0014] In an exemplary embodiment of the present disclosure, forming a 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 distributed at intervals; forming a first etching material layer on the sidewall of the first mask structure to serve as the first etching area; A first filling material is filled between the structure jointly constituted 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 constitute the first mask region.

[0015] In an exemplary embodiment of the present disclosure, 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 the sidewall of the third mask structure to serve as the second etching area; A second filling material is filled between the structure 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.

[0016] In an exemplary embodiment of the present disclosure, the forming method further includes: Before forming the second filling layer, cleaning the second groove; Before forming the third filling layer, the third trench is cleaned.

[0017] In an exemplary embodiment of the present disclosure, the aspect ratio of the first trench is 10:1-8:1.

[0018] In an exemplary embodiment of the present disclosure, the aspect ratio of the second trench is 16:1-20:1; and / or the aspect ratio of the third trench is 16:1-20:1.

[0019] According to one aspect of the present disclosure, a semiconductor structure is provided, wherein the semiconductor structure is formed by the method for forming a semiconductor structure described in any one of the above, and the semiconductor structure includes a plurality of active areas divided by the second trench and the third trench and a plurality of connection areas connected between the second trench and the third trench, and a filling layer is provided in the second trench, the third trench and the connection area; the active area includes a first sidewall and a second sidewall that are arranged opposite each other, the first sidewall and the second sidewall are arranged in parallel, and the first sidewall and the second sidewall both extend in a direction perpendicular to the bottom surface of the substrate; the second trench has an aspect ratio of 16:1 to 20:1; and / or the third trench has an aspect ratio of 16:1 to 20:1.

[0020] The semiconductor structure and its formation method disclosed in the present invention can reduce the capillary force between patterns (such as active area patterns) of the semiconductor structure in the cleaning process by step-by-step etching and gradual filling of the filling layer, and suppress the collapse of high aspect ratio patterns (such as active area patterns) during the cleaning process, and there is no need to use supercritical cleaning or add various surfactants, thereby reducing equipment costs and improving product yield. Specifically, the substrate is etched by step-by-step etching to form a second groove and a third groove with a large depth-to-width ratio, and then the active area is defined by the second groove and the third groove and a plurality of connection areas connected between the second groove and the third groove. In this process, the substrate can be first etched to form a first groove with a relatively small depth and width, and then the first groove can be filled with a first filling layer; part of the first groove can be etched to form a plurality of second grooves. Since there is a first groove filled with the first filling layer between adjacent second grooves, in the subsequent process of cleaning the second groove with a relatively large depth and width, the remaining substrate on at least one side of the second groove (i.e., the side wall of the second groove) can be supported by the first filling layer, thereby reducing the probability of the side wall of the second groove collapsing due to capillary force during the cleaning of the second groove, which helps to improve product yield. At the same time, after forming the second filling layer, 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, in the subsequent process of cleaning the third trench with a larger depth-width ratio, the remaining substrate on at least one side of the third trench (i.e., the sidewall of the third trench) can be supported by the second filling layer, thereby reducing the probability of the sidewall of the third trench collapsing due to the capillary force in the process of cleaning the third trench. That is, the present application can reduce the probability of collapse of the active area defined by the second trench and the third trench and the multiple connection areas connected between the second trench and the third trench, improve the product yield, and do not need to use supercritical cleaning or add various surfactants, thereby reducing equipment costs. In addition, the second filling layer and the third filling layer can be directly used as the trench isolation structure between the active areas, that is, the design of the second filling layer and the third filling layer can not only reduce the probability of collapse of the active area, but also form a trench isolation structure at the same time in the process of forming the active area, so that there is no need to form the trench isolation structure through a separate process in the subsequent process, which can simplify the process and reduce costs.

[0021] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0023] Figure 1 Flow chart of a method for forming a semiconductor structure in an embodiment of the present disclosure.

[0024] Figure 2 It is a schematic diagram of the structure after completing step S120 in one embodiment of the present disclosure.

[0025] Figure 3 It is a schematic diagram of the structure after completing step S120 in another embodiment of the present disclosure.

[0026] Figure 4 For along Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0027] Figure 5 For along Figure 3 Cross-sectional view taken along the cc' direction.

[0028] Figure 6 To complete step S130, the trailing edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0029] Figure 7 To complete step S130, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0030] Figure 8 To complete step S140, the trailing edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0031] Fig. 9 To complete step S140, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0032] Fig.10 To complete step S210, the trailing edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0033] Fig.11 To complete step S210, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0034] Fig.12 In one embodiment of the present disclosure, a first mask material layer and a first photoresist layer are formed. Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0035] Fig.13 In one embodiment of the present disclosure, a first mask material layer and a first photoresist layer are formed. Figure 3 Cross-sectional view taken along the cc' direction.

[0036] Fig.14 In one embodiment of the present disclosure, the first etching material layer is formed at the rear edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0037] Fig.15 In one embodiment of the present disclosure, the first etching material layer is formed at the rear edge Figure 3 Cross-sectional view taken along the cc' direction.

[0038] Fig.16 In one embodiment of the present disclosure, a first filling material is formed at the rear edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0039] Fig.17 In one embodiment of the present disclosure, a first filling material is formed at the rear edge Figure 3 Cross-sectional view taken along the cc' direction.

[0040] Fig.18 In one embodiment of the present disclosure, the second filling layer is formed at the rear edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0041] Fig.19 In one embodiment of the present disclosure, the second filling layer is formed at the rear edge Figure 3 Cross-sectional view taken along the cc' direction.

[0042] Fig. 20 In the embodiment of the present disclosure, the step S160 is completed. Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0043] Fig.21 To complete step S410, the trailing edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0044] Fig. 22 To complete step S410, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0045] Fig.23 In one embodiment of the present disclosure, a second mask material layer and a second photoresist layer are formed. Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0046] Fig.24 In one embodiment of the present disclosure, a second mask material layer and a second photoresist layer are formed. Figure 3 Cross-sectional view taken along the cc' direction.

[0047] Fig.25 In one embodiment of the present disclosure, a third mask structure is formed at the rear edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0048] Fig.26 In one embodiment of the present disclosure, a second etching material layer and a second filling material back edge are formed. Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0049] Fig. 27 To complete step S170, the trailing edge Figure 2 aa' direction or along Figure 3 Cross-sectional view taken along the bb' direction.

[0050] Fig.28 In the embodiment of the present disclosure, the third mask layer and the photoresist layer are formed at the rear edge Figure 3 Cross-sectional view taken along the cc' direction.

[0051] Fig.29 To complete step S630, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0052] Fig.30 To complete step S190, the trailing edge Figure 3 Cross-sectional view taken along the cc' direction.

[0053] Description of reference numerals: 1. substrate; 101. first groove; 102. second groove; 103. third groove; 11. initial active group; 111. initial active area; 112. first gap; 113. second gap; 114. active area; 115. connection area; 21. first filling layer; 22. second filling layer; 23. third filling layer; 24. fourth filling layer; 31. first mask layer; 301. first sub-film layer; 302. second sub-film layer; 303. third sub-film layer; 304. fourth sub-film layer; 305. fifth sub-film layer; 306. sixth sub-film 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 area; 315, first etching area; 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 area; 325, second etching area; 33, third mask layer; 4, photoresist layer; 41, developing area; x, first direction; y, second direction; 51, first photoresist layer; 52, second photoresist layer. DETAILED DESCRIPTION

[0054] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed descriptions will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0055] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the illustration to another component, these terms are used in this specification only for convenience, such as according to the orientation of the examples described in the drawings. It is understood that if the device of the illustration is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" other structures, it may mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0056] 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 "including" and "having" are used to express an open-ended inclusive meaning and mean that additional elements / components / etc. may exist in addition to the listed elements / components / etc.; the terms "first", "second", "third" and "fourth" etc. are used merely as labels and are not intended to limit the quantity of their objects.

[0057] The process of manufacturing the active area and trench isolation structure of the semiconductor structure usually includes: etching the substrate to form a trench, dividing the substrate into a plurality of spaced active areas through the trench, cleaning the sidewalls of the trench, and then filling the trench with insulating material to form a trench isolation structure. However, in order to ensure the isolation effect between the active areas, the depth-to-width ratio of the trench is often large (usually greater than 15). In the process of cleaning the trench, the active area pattern on the sidewall of the trench is easily collapsed or deformed under the action of capillary force, which seriously affects the product yield. In the related art, supercritical fluid drying is usually used to reduce or eliminate the surface tension or capillary force of the cleaning liquid to prevent the active area from collapsing, but this has high requirements on the equipment and high cost. Alternatively, various surfactants are added to the cleaning liquid to reduce the surface tension or capillary force, but the cleaning liquid surfactant will remain on the surface of the wafer, affecting the product yield.

[0058] Based on this, the present disclosure provides a method for forming a semiconductor structure, such as Figure 1 As shown, the forming method includes steps S110 to S170, wherein: Step S110, providing a substrate; Step S120, etching the substrate to form a plurality of first grooves distributed at intervals; Step S130, forming a first filling layer, the first filling layer filling the first trench and covering the surface of the etched substrate; Step S140, etching part of the first trenches to form a plurality of second trenches, wherein a first trench filled with the first filling layer is provided between each two adjacent second trenches; Step S150, forming a second filling layer, wherein the second filling layer fills the second trench; Step S160, etching the remaining first trenches to form third trenches, wherein a second trench filled with a second filling layer is provided between two adjacent third trenches; Step S170 , forming a third filling layer, wherein the third filling layer fills the third trench.

[0059] The method for forming a semiconductor structure disclosed in the present invention can reduce the capillary force between patterns (such as active area patterns) of the semiconductor structure in the cleaning process by step-by-step etching and gradual filling of the filling layer, and suppress the collapse of high aspect ratio patterns (such as active area patterns) during the cleaning process, and there is no need to use supercritical cleaning or add various surfactants, thereby reducing equipment costs and improving product yield. Specifically, the substrate is etched in a step-by-step etching manner to form a second groove and a third groove with a large depth-to-width ratio, and then the active area is defined by the second groove and the third groove and a plurality of connection areas connected between the second groove and the third groove. In this process, the substrate can be first etched to form a first groove with a relatively small depth and width, and then the first groove can be filled with a first filling layer; part of the first groove can be etched to form a plurality of second grooves. Since there is a first groove filled with the first filling layer between adjacent second grooves, in the subsequent process of cleaning the second groove with a relatively large depth and width, the remaining substrate on at least one side of the second groove (i.e., the side wall of the second groove) can be supported by the first filling layer, thereby reducing the probability of the side wall of the second groove collapsing due to capillary force during the cleaning of the second groove, which helps to improve product yield. At the same time, after forming the second filling layer, 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, in the subsequent process of cleaning the third trench with a larger depth-width ratio, the remaining substrate on at least one side of the third trench (i.e., the sidewall of the third trench) can be supported by the second filling layer, thereby reducing the probability of the sidewall of the third trench collapsing due to the capillary force in the process of cleaning the third trench. That is, the present application can reduce the probability of collapse of the active area defined by the second trench and the third trench and the multiple connection areas connected between the second trench and the third trench, improve the product yield, and do not need to use supercritical cleaning or add various surfactants, thereby reducing equipment costs. In addition, the second filling layer and the third filling layer can be directly used as the trench isolation structure between the active areas, that is, the design of the second filling layer and the third filling layer can not only reduce the probability of collapse of the active area, but also form a trench isolation structure at the same time in the process of forming the active area, so that there is no need to form the trench isolation structure through a separate process in the subsequent process, which can simplify the process and reduce costs.

[0060] The specific steps of the method for forming the semiconductor structure disclosed in the present invention and its implementation details are described in detail below: like Figure 1 As shown, in step S110, a substrate is provided.

[0061] The substrate may be a flat plate structure, which may be rectangular, circular, elliptical, polygonal or irregular in shape, and its material may be a semiconductor material, for example, its material may be silicon, but is not limited to silicon or other semiconductor materials. No special limitation is made to the shape and material of the substrate.

[0062] like Figure 1 As shown, in step S120, the substrate is etched to form a plurality of first trenches distributed at intervals.

[0063] like Figure 2 and Figure 3 As shown, the first grooves 101 may be strip-shaped, for example, the first grooves 101 may be spaced apart along the first direction x and extend along the second direction y. The substrate 1 may be etched by an anisotropic etching process (for example, dry etching) to form a plurality of first grooves 101 spaced apart along the first direction x (for example, Figure 4 and Figure 5 as shown).

[0064] Both the first direction x and the second direction y may be directions parallel to the bottom surface of the substrate 1, and the second direction y may intersect with the first direction x, for example, the second direction y and the first direction x may be perpendicular to each other. It should be noted that perpendicularity may be absolutely perpendicular or approximately perpendicular, and deviations are inevitable during the manufacturing process. In the present disclosure, the angle deviation may be caused by manufacturing process limitations, so that the angle between the second direction y and the first direction x has a certain deviation. As long as the angle deviation between the second direction y and the first direction x is within a preset range, the second direction y may be considered perpendicular to the first direction x. For example, the preset range may 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 may be considered perpendicular to the first direction x.

[0065] In an exemplary embodiment of the present disclosure, please continue to refer to Figure 2 and Figure 3 As 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 first grooves 101 are provided between adjacent initial active groups 11; that is, a plurality of initial active groups 11 and a plurality of first grooves 101 are alternately provided along the first direction x, for example, a first groove 101 is provided between every two adjacent initial active groups 11, and at the same time, an initial active group 11 is provided between every two adjacent first grooves 101.

[0066] 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 regions 111 that are spaced apart along the second direction y; the gap between adjacent initial active regions 111 distributed along the second direction y can be defined as the first gap 112. Taking the initial active region 111 as a reference, two adjacent initial active groups 11 are arranged in alignment, and two adjacent first trenches 101 can communicate through the first gap 112 between two adjacent initial active regions 111 that are spaced apart along the second direction y; and each first gap 112 distributed along the second direction y communicates with the first trenches 101 on both of its sides. The first trenches 101 and the first gaps 112 define the initial active regions 111 as columnar structures, and the columnar initial active regions 111 are arranged in an array in the form of rows and columns. That is to say, the second direction is perpendicular to the first direction.

[0067] In some 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 regions 111 that extend along the second direction y and are spaced apart along the second direction y. The gap between adjacent initial active regions 111 distributed along the second direction y can be defined as the second gap 113. Taking the initial active region 111 as a reference, two adjacent initial active groups 11 can be staggeredly distributed, and two adjacent first trenches 101 can communicate through the second gap 113 between two adjacent initial active regions 111 that are spaced apart along the second direction y; and each second gap 113 distributed along the second direction y communicates with the first trenches 101 on both of its sides. The first trenches 101 and the second gaps 113 define the initial active regions 111 as block structures, and the cross-section of the block structure is strip-shaped.

[0068] In an exemplary embodiment of the present disclosure, the aspect ratio of the first trench 101 can be 10:1 to 8:1. For example, its aspect ratio can be 8:1, 8.5:1, 9:1, 9.5:1, 10:1. Of course, the aspect ratio of the first trench 101 can also be other ratios, which will not be listed one by one here. For example, when the aspect ratios of the finally to be formed second trench 102 and third trench 103 are 16:1 to 20:1, the aspect ratio of the first trench 101 can be 10:1 to 8:1.

[0069] In some embodiments of the present disclosure, after the first trench 101 is formed, the first trench 101 can also be cleaned to remove impurities. During this process, since the aspect ratio of the first trench 101 is relatively small, generally no phenomena such as collapse or deformation will occur. Therefore, during this cleaning process, there is no need to use a supercritical fluid drying device for drying, and the manufacturing cost is relatively low; at the same time, there is no need to add a surfactant to the cleaning solution to reduce the surface tension or capillary force, and the residue is less, which has little impact on the product yield.

[0070] As Figure 1As shown, in step S130, a first filling layer is formed, and the first filling layer fills the first trench and covers the surface of the etched substrate.

[0071] The material of the first filling layer 21 may be an insulating material, for example, silicon oxide, silicon nitride, silicon oxynitride, etc. The first filling material layer may be formed on the surface of the substrate 1 having the first grooves 101 by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, and the first filling material layer may fill each first groove 101. The first filling material layer may be subjected to chemical mechanical polishing so that the thickness of each area on its surface is substantially the same, and the first filling material layer remaining after chemical mechanical polishing may be used as the first filling layer 21. In some embodiments of the present disclosure, after completing step S130, the first filling material layer may be formed by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, and the first filling material layer may be formed by chemical vapor deposition, physical vapor deposition, or atomic layer deposition, and the first filling material layer may fill each first groove 101. Figure 2 aa' direction or along Figure 3 The cross-sectional structure cut along the bb' direction is as follows Figure 6 As shown; after completing step S130, the back edge Figure 3 The cross-sectional structure cut along the cc' direction is as follows Figure 7 shown.

[0072] like Figure 1 As shown, in step S140, a portion of the first trenches are etched to form a plurality of second trenches, and a first trench filled with the first filling layer is provided between each two adjacent second trenches.

[0073] The aspect ratio of the second groove 102 may be 16:1 to 20:1. For example, its aspect ratio may be 16:1, 17:1, 18:1, 19:1 or 20:1. Of course, the aspect ratio of the second groove 102 may also be other ratios, which are not listed here. In some embodiments of the present disclosure, a first groove 101 filled with the first filling layer 21 is provided between any two adjacent second grooves 102 among the plurality of second grooves 102. Part of the first groove 101 may be etched by an anisotropic etching process (for example, dry etching) to form the second groove 102. In some embodiments of the present disclosure, after completing step S140, the first groove 101 is formed. Figure 2 aa' direction or along Figure 3 The cross-sectional structure cut along the bb' direction is as follows Figure 8 As shown; after completing step S140, the back edge Figure 3 The cross-sectional structure cut along the cc' direction is as follows Fig. 9 shown.

[0074] In an exemplary embodiment of the present disclosure, etching a portion of the first trench 101 to form a plurality of second trenches 102, wherein there is a first trench 101 filled with the first filling layer 21 between two adjacent second trenches 102 (i.e., step S140) may include steps S210 and S220, wherein: In step S210, a first mask layer 31 is formed on a side of the first filling layer 21 away from the substrate 1. The first mask layer 31 includes a plurality of first mask areas 314 that are spaced apart and first etching areas 315 that are located on opposite sides of the first mask areas 314. The orthographic projection of the first etching areas 315 on the substrate 1 coincides with the orthographic projection of part of the first groove 101 on the substrate 1, and the orthographic projection of the first mask area 314 on the substrate 1 covers the orthographic projection of the remaining first groove 101 on the substrate 1.

[0075] like Fig.10 and Fig.11 As shown, the first mask layer 31 can be formed on the first filling layer 21 by 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 methods, and the formation method of the first mask layer 31 is not particularly limited here. In some embodiments of the present disclosure, the first mask layer 31 may include a plurality of first mask areas 314 distributed at intervals, and the first mask areas 314 may be in a strip shape, and the two sides of the strip-shaped first mask areas 314 are parallel and oppositely arranged, and the areas adjacent to the two sides of each first mask area 314 are all first etching areas 315.

[0076] In some embodiments of the present disclosure, the orthographic projections of each first etching region 315 on the substrate 1 overlap with the orthographic projections of different first trenches 101 on the substrate 1; at the same time, the orthographic projections of each first mask region 314 on the substrate 1 cover the orthographic projections of the remaining first trenches 101 (i.e., the orthographic projections of each first trench 101 on the substrate 1 that do not overlap or overlap with the orthographic projections of the first etching region 315 on the substrate 1) on the substrate 1. For example, the first mask region 314 may cover the area of ​​the first filling layer 21 that is not covered by the first etching region 315.

[0077] In some embodiments of the present disclosure, the first etching regions 315 and the first mask regions 314 may be alternately distributed, and one first mask region 314 may be provided between two adjacent first etching regions 315 , or one first etching region 315 may be provided between two adjacent first mask regions 314 .

[0078] In an exemplary embodiment of the present disclosure, forming the first mask layer 31 on the side of the first filling layer 21 away from the substrate 1 (ie, step S210) may include steps S310 to S340, wherein: In step S310 , a first mask material layer 311 is formed on a side of the first filling layer 21 away from the substrate 1 .

[0079] like Fig.12 and Fig.13As shown, the first mask material layer 311 may be a composite film layer composed of a multi-layer film structure, or may be a single-layer film structure, which is not particularly limited 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 stacked and distributed in sequence from bottom to top along a direction perpendicular to the substrate 1, wherein the material of the first sub-film layer 301 may be carbon, the material of the second sub-film layer 302 may be silicon oxynitride, the material of the third sub-film layer 303 may be a spin-on hard mask, and the material of the fourth sub-film layer 304 may be silicon oxynitride. The first sub-film layer 301 and the second sub-film layer 302 can be formed in sequence on the first filling layer 21 by chemical vapor deposition, physical vapor deposition or atomic layer deposition, and then the third sub-film layer 303 can be formed on the second sub-film layer 302 by spin coating, and 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.

[0080] Step S320 , etching the first mask material layer 311 to form a plurality of first mask structures 3111 that are spaced apart from each other.

[0081] Please continue to see Fig.12 and Fig.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 the remaining first photoresist layer 51 is used as a mask to etch the fourth sub-film layer 304 and the third sub-film layer 303 in the first mask material layer 311, thereby forming a plurality of first mask structures 3111 (such as Fig.14 and Fig.15 as shown).

[0082] It should be noted that after forming the first mask structure 3111 , the first photoresist layer 51 may be removed, and the first mask structure 3111 may be cleaned to remove residual etching gas and residual byproducts.

[0083] In step S330 , a first etching material layer 312 is formed on the sidewall of the first mask structure 3111 to serve as a first etching region 315 .

[0084] Please continue to see Fig.14 and Fig.15As shown, the material of the first etching material layer 312 is different from the materials 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 side wall of the first mask structure 3111 by chemical vapor deposition, physical vapor deposition or atomic layer deposition. In this process, for the convenience of the process, the first etching material layer 312 can be formed on the top surface exposed in the second sub-film layer 302 and the top surface of the first mask structure 3111 at the same time.

[0085] In step S340 , the first filling material 313 is filled between the structure 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 together form the first mask region 314 .

[0086] like Fig.16 and Fig.17 As shown, a first filling material 313 may be formed on a side of the first etching material layer 312 away from the substrate 1 until the first filling material 313 fills the gap between adjacent first mask structures 3111. In some embodiments of the present disclosure, the first filling material 313 may 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 may be etched after the first filling material 313 is etched back, 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 (such as Fig.10 and Fig.11 ). In some other embodiments of the present disclosure, after forming the first filling material 313, the first filling material 313 and the first etching material layer 312 except the top of the first mask structure 3111 may be chemically mechanically polished to make the top of the first filling material 313 and the top of the first etching material layer 312 flush with the top surface of the first mask structure 3111. The remaining first filling material 313 may be used as the second mask structure 3131, and the remaining first etching material layer 312 may be used as the first etching region 315.

[0087] In step S220 , the first etching region 315 , the first filling layer 21 directly below the first etching region 315 , and the first trench 101 directly below the first etching region 315 are etched using the first mask region 314 as a mask to form a second trench 102 in the substrate 1 .

[0088] A dry etching process may be used to etch each first etching region 315, the first filling layer 21 directly below each first etching region 315, and the first trench 101 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.

[0089] In some embodiments of the present disclosure, the depth of the second groove 102 may be 1.5 to 2.2 times the depth of the first groove 101 . For example, the depth of the second groove 102 is 1.5, 1.7, 1.9, 2.1 or 2.2 times the depth of the first groove 101 .

[0090] like Figure 1 As shown, in step S150 , a second filling layer 22 is formed, and the second filling layer 22 fills the second trench 102 .

[0091] 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 or chemical mechanical polishing, thereby exposing the surface of the remaining first filling layer 21 (eg, Figure 8 and Fig. 9 as shown).

[0092] The material of the second filling layer 22 may be an insulating material, for example, the material of the second filling layer 22 may include silicon oxide and / or silicon nitride. Fig.18 and Fig.19 As shown, an insulating material may be deposited on the surface of the structure formed by the first filling layer 21 and the second groove 102 by chemical vapor deposition, physical vapor deposition or atomic layer deposition, thereby forming the second filling layer 22. In this process, the insulating material may fill the second groove 102. The insulating material may be chemically mechanically polished to have a flat surface, and the remaining insulating material may be used as the second filling layer 22.

[0093] In an exemplary embodiment of the present disclosure, before forming the second filling layer 22, the second trench 102 may be cleaned to remove residues, which helps to improve device reliability. After cleaning the second trench 102, the second filling layer 22 formed in the second trench 102 may be used as a trench isolation structure, that is, in the process of forming the active area 114, the present disclosure may simultaneously form a trench isolation structure, so that there is no need to form the trench isolation structure through a separate process later, which may simplify the process and reduce costs.

[0094] It should be noted that, since there is a first groove 101 filled with the first filling layer 21 between adjacent second grooves 102, during the process of cleaning the second grooves 102, the remaining substrate 1 on at least one side of the second groove 102 (i.e., the side wall of the second groove 102) can be supported by the first filling layer 21, which can reduce the probability of the side wall of the second groove 102 collapsing due to capillary force during the cleaning process of the second groove 102, thereby helping to improve product yield.

[0095] like Figure 1 As shown, in step S160 , the remaining first trenches 101 are etched to form third trenches 103 , and a second trench 102 filled with the second filling layer 22 is provided between two adjacent third trenches 103 .

[0096] like Fig. 20 As shown, the aspect ratio of the third trench 103 may be the same as the aspect ratio of the second trench 102. For example, the aspect ratio of the third trench 103 may be 16:1 to 20:1. For example, its aspect ratio may be 16:1, 17:1, 18:1, 19:1 or 20:1. Of course, the aspect ratio of the third trench 103 may also be other ratios, which are not listed here. In some embodiments of the present disclosure, a second trench 102 filled with a second filling layer 22 is provided between any two adjacent third trenches 103 among the plurality of third trenches 103. The remaining first trenches 101 may be etched by an anisotropic etching (e.g., dry etching) process to form the third trenches 103.

[0097] In an exemplary embodiment of the present disclosure, etching the remaining first trenches 101 to form third trenches 103, and a second trench 102 filled with the second filling layer 22 is provided between two adjacent third trenches 103 (ie, step S160), which may include steps S410 and S420, wherein: In step S410, a second mask layer 32 is formed on a side of the second filling layer 22 away from the substrate 1, wherein the second mask layer 32 includes a plurality of spaced second mask areas 324 and second etching areas 325 located on opposite sides of the second mask areas 324, wherein the orthographic projection of the second etching areas 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 areas 324 on the substrate 1 covers the orthographic projection of the second grooves 102 on the substrate 1.

[0098] like Fig.21 and Fig. 22As shown, the second mask layer 32 can be formed on the second filling layer 22 by chemical vapor deposition, physical vapor deposition, atomic layer deposition and / or spin coating. Of course, the second mask layer 32 can also be formed by other methods, and the formation method of the second mask layer 32 is not particularly limited here. In some embodiments of the present disclosure, the second mask layer 32 may include a plurality of second mask areas 324 distributed at intervals, and the second mask areas 324 may be in a strip shape, and the two sides of the strip-shaped second mask areas 324 are parallel and oppositely arranged, and the areas adjacent to the two sides of each second mask area 324 are all second etching areas 325.

[0099] In some embodiments of the present disclosure, the orthographic projections of each second etching region 325 on the substrate 1 respectively coincide with the orthographic projections of different first trenches 101 among the remaining first trenches 101 on the substrate 1; meanwhile, the orthographic projections of each second mask region 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 area of ​​the second filling layer 22 that is not covered by the second etching region 325.

[0100] In some embodiments of the present disclosure, each second etching region 325 and each second mask region 324 may be alternately distributed, and one second mask region 324 may be provided between two adjacent second etching regions 325, or one second etching region 325 may be provided between two adjacent second mask regions 324. That is, before etching the remaining first trenches 101, one first trench 101 may be provided between any two adjacent second trenches 102 among the plurality of second trenches 102.

[0101] 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 (ie, step S410) may include steps S510 to S540, wherein: Step S510 , forming a second mask material layer 321 on a side of the second filling layer 22 away from the substrate 1 .

[0102] like Fig.23 and Fig.24As shown, the second mask material layer 321 may be a composite film layer composed of a multi-layer film structure, or may be a single-layer film structure, which is not particularly limited herein. 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-film layer 301, a second sub-film layer 302, a third sub-film layer 303, and a fourth sub-film layer 304 stacked in sequence from bottom to top in a direction perpendicular to the substrate 1, wherein the material of the first sub-film layer 301 may be carbon, the material of the second sub-film layer 302 may be silicon oxynitride, the material of the third sub-film layer 303 may be a spin-on hard mask, and the material of the fourth sub-film layer 304 may be silicon oxynitride. The first sub-film layer 301 and the second sub-film layer 302 can be formed in sequence on the second filling layer 22 by chemical vapor deposition, physical vapor deposition or atomic layer deposition, and then the third sub-film layer 303 can be formed on the second sub-film layer 302 by spin coating, and 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.

[0103] Step S520 , etching the second mask material layer 321 to form a plurality of third mask structures 3211 that are spaced apart from each other.

[0104] Please continue to see Fig.23 and Fig.24 As shown, a second photoresist layer 52 can be formed on the surface of the fourth sub-film layer 304 away from the substrate 1, the second photoresist layer 52 can be exposed and developed, and the remaining second photoresist layer 52 is used as a mask to etch the fourth sub-film layer 304 and the third sub-film layer 303 in the second mask material layer 321, thereby forming a plurality of third mask structures 3211 spaced apart along the first direction x, as shown in FIG. Fig.25 shown.

[0105] It should be noted that after forming the third mask structure 3211 , the second photoresist layer 52 may be removed, and the third mask structure 3211 may be cleaned to remove residual etching gas and residual byproducts.

[0106] In step S530 , a second etching material layer 322 is formed on the sidewalls of the third mask structure 3211 to serve as a second etching region 325 .

[0107] 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 may be silicon oxide. Fig.26As shown, a second etching material layer 322 can be formed on the side wall of the third mask structure 3211 by chemical vapor deposition, physical vapor deposition or atomic layer deposition. In 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-membrane layer 302 in the second mask material layer 321 and the top surface of the third mask structure 3211.

[0108] Step S540 , filling the second filling material 323 between the structure formed by the third mask structure 3211 and the second etching area 325 to form a plurality of fourth mask structures 3231 distributed at intervals, and the third mask structure 3211 and the fourth mask structure 3231 together form the second mask area 324 .

[0109] Please continue to see Fig.26As shown, a second filling material 323 may be deposited on the side of the second etching material layer 322 away from the substrate 1 until the second filling material 323 fills the gap between adjacent third mask structures 3211. In some embodiments of the present disclosure, the second filling material 323 may be etched back so that the top surface of the second filling material 323 is 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 the second filling material 323 is etched back, thereby removing the second etching material layer 322 located on the top of the third mask structure 3211, and making 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 forming the second filling material 323, chemical mechanical polishing may be performed on the second filling material 323 and the second etching material layer 322 except for 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 flush with the top surface of the third mask structure 3211. The remaining second filling material 323 may be used as the fourth mask structure 3231, and the remaining second etching material layer 322 may be used as the second etching region 325. It should be noted that, since the cc' cross-sectional direction is always covered by the second photoresist layer 52 during the process of forming the third mask structure 3211 and the fourth mask structure 3231, the structure of the second mask material layer 321 in the cc' cross-sectional direction is not destroyed, and the second etching material layer 322 and the second filling material 323 formed subsequently are sequentially laid on the second mask material layer 321. In the process of etching back (or grinding) the second filling material 323 and the second mask material layer 321, for the cc' cross-sectional 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-sectional direction is the same as the structure of the second mask material layer 321, as shown in FIG. Fig. 22 shown.

[0110] In step S420 , the second etching region 325 , the first filling layer 21 directly below the second etching region 325 , and the first trench 101 directly below the second etching region 325 are etched using the second mask region 324 as a mask to form a third trench 103 in the substrate 1 .

[0111] A dry etching process may be used to etch each second etching region 325, the first filling layer 21 directly below each second etching region 325, and the first trench 101 directly below each second etching region 325 using 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.

[0112] In some embodiments of the present disclosure, the depth of the third groove 103 may be 1.5 to 2.2 times the depth of the first groove 101 . For example, the depth of the third groove 103 is 1.5, 1.7, 1.9, 2.1 or 2.2 times the depth of the first groove 101 .

[0113] like Figure 1 As shown, in step S170 , a third filling layer 23 is formed, and the third filling layer 23 fills the third trench 103 .

[0114] 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 product reliability. In the process of cleaning the third trench 103, since there is a second trench 102 filled with the second filling layer 22 between two adjacent third trenches 103, in the process of cleaning the third trench 103, the substrate 1 remaining on at least one side of the third trench 103 (i.e., the sidewall of the third trench 103) can be supported by the second filling layer 22, thereby reducing the probability of the sidewall of the third trench 103 collapsing due to the capillary force in the process of cleaning the third trench 103, that is, the present application can reduce the probability of collapse of the active area 114 defined by the second trench 102 and the third trench 103, thereby improving the product yield. In addition, the third filling layer 23 can be directly used as a trench isolation structure between the active areas 114. That is, the design of the third filling layer 23 can not only reduce the probability of collapse of the active area 114, but also enable the trench isolation structure to be formed simultaneously in the process of forming the active area 114, so that there is no need to form the trench isolation structure through a separate process subsequently, which can simplify the process and reduce costs.

[0115] 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 groove 103 by chemical vapor deposition, physical vapor deposition or atomic layer deposition, thereby forming the third filling layer 23. In this process, the insulating material may fill the third groove 103. The insulating material may be subjected to chemical mechanical grinding to have a flat surface, and the remaining insulating material may be used as the third filling layer 23. In the embodiment of the present disclosure, after completing step S170, the insulating material is deposited on the surface of the structure formed by the second filling layer 22 and the third groove 103. Figure 2 aa' direction or along Figure 3 The cross-sectional structure cut along the bb' direction is as follows Fig. 27 shown.

[0116] In an exemplary embodiment of the present disclosure, please continue to refer to Figure 2 and Figure 3 As shown, the first gap 112 between two adjacent first grooves 101 and / or the second gap 113 between two adjacent first grooves 101 can be used as a connection area. In the first direction x, the connection areas and the first grooves 101 are alternately distributed in sequence, and the first filling layer 21 also fills the connection area.

[0117] The method for forming a semiconductor structure disclosed in the present invention further includes step S180 and step S190, wherein: Step S180 , after forming the third filling layer 23 , etching the first filling layer 21 and the connection region in the connection region to increase the depth of the connection region in the substrate 1 .

[0118] The connection area and the first filling layer 21 filled in the connection area can be etched by a dry etching process, thereby increasing the depth of the connection area. The depth of the connection area can be substantially the same as the depth of the second trench 102 or the third trench 103, or the depth of the connection area can be slightly greater than the depth of the first trench 101 or the third trench 103, which is not particularly limited here.

[0119] In an exemplary embodiment of the present disclosure, after forming the third filling layer 23, etching the first filling layer 21 and the connection area in the connection area to increase the depth of the connection area in the substrate 1 (ie, step S180) may include steps S610 to S630, wherein: In step S610 , a third mask layer 33 is formed on a side of the first filling layer 21 , the second filling layer 22 , and the third filling layer 23 away from the substrate 1 .

[0120] like Fig.28As shown, the third mask layer 33 may be a single-layer film structure or a composite film structure composed of multiple film layers, which is not particularly limited here. For example, the third mask layer 33 may include a fifth sub-film layer 305 and a sixth sub-film layer 306, wherein the material of the fifth sub-film layer 305 may be a spin-coated hard mask, and the material of the sixth sub-film layer 306 may be silicon oxynitride. The fifth sub-film layer 305 may be formed by a process such as spin coating, and the sixth sub-film layer 306 may be formed by chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

[0121] Step S620 , forming a photoresist layer 4 on a side of the third mask layer 33 away from the substrate 1 , wherein the photoresist layer 4 includes a plurality of developing regions 41 , and the orthographic projections of the developing regions 41 on the substrate 1 coincide with the orthographic projections of the connecting regions on the substrate 1 .

[0122] Please continue to see Fig.28 As shown, a photoresist layer 4 can be formed on the third mask layer 33 by spin coating or the like. The material of the photoresist layer 4 can be a photoresist, for example, a positive photoresist or a negative photoresist, which is not particularly limited here. The photoresist layer 4 can be exposed and developed to form a plurality of development areas 41, and the orthographic projections of the development areas 41 on the substrate 1 respectively coincide with the orthographic projections of different connection areas on the substrate 1.

[0123] In step S630 , the first filling layer 21 and the connection region 115 directly below the first filling layer 21 are etched in the developing region 41 to increase the depth of the connection region 115 in the substrate 1 .

[0124] like Fig.29 As shown, the remaining photoresist layer 4 after development can be used as a mask, and the third mask layer 33, the first filling layer 21 below the third mask layer 33, and the connection area 115 directly below the first filling layer 21 are etched in the development area 41 to increase the depth of the connection area 115 in the substrate 1.

[0125] Step S190 , forming a fourth filling layer 24 , wherein the fourth filling layer 24 fills the connection area 115 with an increased depth.

[0126] In an exemplary embodiment of the present disclosure, Fig.30As shown, after increasing the depth of the connection area 115, the connection area 115 can also be cleaned. In this process, the second filling layer 22 and the third filling layer 23 can support the remaining substrate 1 around the connection area 115, which can effectively reduce the probability of collapse of the remaining substrate 1 around the connection area 115 during the cleaning process. 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 area 115 with increased depth. The second trench 102, the third trench 103 and the connection area 115 with increased depth can jointly divide the substrate 1 into a plurality of spaced active areas 114; the fourth filling layer 24 can form a shallow trench isolation structure (STI for short) that fills the gaps between the active areas 114 together with the second filling layer 22 and the third filling layer 23.

[0127] In the process of forming the active area 114, the present invention simultaneously forms a shallow trench isolation structure for isolating each active area 114, so that there is no need to form the trench isolation structure through a separate process in the future, which can simplify the process and reduce costs. In addition, in the process, different areas of the shallow trench isolation structure are used to support other areas, which can prevent the active area 114 from collapsing due to the surface tension or capillary force of the liquid during the cleaning process. Compared with the prior art, the present invention only needs to use a conventional cleaning solution in the process of cleaning the second groove 102, the third groove 103 and the connection area 115, 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 active agent and improve the product yield. At the same time, the present invention does not need to use supercritical fluid drying to reduce or eliminate the surface tension or capillary force of the cleaning solution, and has low equipment requirements and low process costs.

[0128] It should be noted that, although the steps of the method for forming a semiconductor structure in the present disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0129] 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 areas 114 divided by a second trench 102 and a third trench 103 and a plurality of connection areas 115 connected between the second trench 102 and the third trench 103, and a filling layer is provided in the second trench 102, the third trench 103 and the connection area 115; the active area 114 includes a first side wall and a second side wall that are arranged opposite to each other, the surfaces of the first side wall and the second side wall are both planes, the first side wall and the second side wall can be arranged in parallel, and the first side wall and the second side wall both extend in a direction perpendicular to the bottom surface of the substrate 1.

[0130] In some embodiments of the present disclosure, the second grooves 102 and the third grooves 103 may be alternately distributed in sequence along the first direction x, and a third groove 103 may be provided between two adjacent second grooves 102, or a second groove 102 may be provided between two adjacent third grooves 103, and the adjacently distributed second grooves 102 and third grooves 103 may be connected through a plurality of connection areas 115.

[0131] In some embodiments of the present disclosure, the second trench 102 has an aspect ratio of 16:1 to 20:1; for example, its aspect ratio may be 16:1, 17:1, 18:1, 19:1 or 20:1. Of course, the aspect ratio of the second trench 102 may also be other ratios, which are not listed here. The aspect ratio of the third trench 103 may be the same as that of the second trench 102, for example, the aspect ratio of the third trench 103 may be 16:1 to 20:1, for example, the aspect ratio of the third trench 103 and the second trench 102 may both be 16:1, 17:1, 18:1, 19:1 or 20:1.

[0132] Other details and beneficial effects of the semiconductor structure disclosed in the present invention have been described in detail in the embodiments of the corresponding method for forming the semiconductor structure, and therefore, they will not be repeated here.

[0133] Those skilled in the art will readily appreciate 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 knowledge or customary techniques in the art that are not disclosed in the present disclosure. The description and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: providing a substrate; Etching the substrate to form a plurality of first grooves spaced apart from each other; forming a first filling layer, wherein the first filling layer fills the first trench and covers the surface of the etched substrate; Etching part of the first trenches to form a plurality of second trenches, wherein each of two adjacent second trenches has a first trench filled with the first filling layer; forming a second filling layer, wherein the second filling layer fills the second trench; Etching the remaining first trenches to form third trenches, wherein the second trench filled with the second filling layer is provided between two adjacent third trenches; A third filling layer is formed, wherein the third filling layer fills the third trench.

2. The forming method according to claim 1, characterized in that: The etching of part of the first trenches to form a plurality of second trenches, wherein each of two adjacent second trenches has a first trench filled with the first filling layer, comprises: forming a first mask layer on a side of the first filling layer away from the substrate, the first mask layer comprising a plurality of first mask areas distributed at intervals and first etching areas located on opposite sides of the first mask areas, the orthographic projections of the first etching areas on the substrate coincide with the orthographic projections of a portion of the first grooves on the substrate, and the orthographic projections of the first mask areas on the substrate cover the orthographic projections of the remaining first grooves on the substrate; The first etching region, the first filling layer directly below the first etching region, and the first trench directly below the first etching region are etched using the first mask region as a mask to form the second trench in the substrate.

3. The forming method according to claim 2, characterized in that: The forming method further comprises: Before forming the second filling layer, removing the remaining first mask layer; The forming of a second filling layer, wherein the second filling layer fills the second trench, comprises: A second filling layer is formed on the surface of the structure formed by the first filling layer and the second groove, and the second filling layer fills the second groove.

4. The forming method according to claim 3, characterized in that: The etching of the remaining first trenches to form third trenches, wherein each of two adjacent third trenches has a second trench filled with the second filling layer, comprises: forming a second mask layer on a side of the second filling layer away from the substrate, the second mask layer comprising a plurality of second mask areas distributed at intervals and second etching areas located on opposite sides of the second mask areas, the orthographic projections of the second etching areas on the substrate coincide with the orthographic projections of the remaining first grooves on the substrate, and the orthographic projections of the second mask areas on the substrate cover the orthographic projections of the second grooves on the substrate; The second etching region, the first filling layer directly below the second etching region, and the first trench directly below the second etching region are etched using the second mask region as a mask to form the third trench in the substrate.

5. The forming method according to claim 1, characterized in that: 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, characterized in that: The etching of the substrate to form a plurality of first grooves spaced apart from each other comprises: The substrate is etched to form a plurality of initial active groups spaced apart along a first direction, wherein the first grooves are disposed between adjacent initial active groups; each initial active group includes a plurality of initial active regions spaced apart along a second direction; two adjacent initial active groups are aligned with each other based on the initial active regions, and two adjacent first grooves are connected via a first gap between two adjacent initial active regions distributed along the second direction; each of the first grooves and each of the first gaps defines the initial active region as a columnar structure, and the second direction is perpendicular to the first direction.

7. The forming method according to claim 1, characterized in that: The etching of the substrate to form a plurality of first grooves spaced apart from each other comprises: The substrate is etched to form a plurality of initial active groups spaced apart along a first direction, with the first grooves being between adjacent initial active groups; each initial active group includes a plurality of initial active regions extending along a second direction and spaced apart along the second direction; two adjacent initial active groups are staggered with respect to the initial active regions, and two adjacent first grooves are connected via a second gap between two adjacent initial active regions spaced apart along the second direction; and the second direction intersects with the first direction.

8. The forming method according to claim 7, characterized in that: The second gap is used as a connection area, and the connection area and the first groove are alternately distributed in sequence; the first filling layer also fills the connection area; The forming method further comprises: After forming the third filling layer, etching the first filling layer and the connection area in the connection area to increase the depth of the connection area in the substrate; A fourth filling layer is formed, wherein the fourth filling layer fills the connection area with an increased depth.

9. The forming method according to claim 8, characterized in that: After forming the third filling layer, etching the first filling layer and the connection area in the connection area to increase the depth of the connection area in the substrate comprises: 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, wherein the photoresist layer comprises a plurality of developing areas, and the orthographic projections of the developing areas on the substrate respectively coincide with the orthographic projections of the connecting areas on the substrate; The first filling layer and the connection region directly below the first filling layer are etched in the development region to increase the depth of the connection region in the substrate.

10. The forming method according to claim 2, characterized in that: The forming of a first mask layer on a side of the first filling layer away from the substrate comprises: 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 distributed at intervals; forming a first etching material layer on the sidewall of the first mask structure to serve as the first etching area; A first filling material is filled between the structure jointly constituted 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 constitute the first mask region.

11. The forming method according to claim 4, characterized in that: The forming of a second mask layer on a side of the second filling layer away from the substrate comprises: 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 the sidewall of the third mask structure to serve as the second etching area; A second filling material is filled between the structure 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 comprises: Before forming the second filling layer, cleaning the second groove; Before forming the third filling layer, the third trench is cleaned.

13. The forming method according to any one of claims 1 to 12, characterized in that: The aspect ratio of the first trench is 10:1-8:

1.

14. The forming method according to claim 13, characterized in that: The second trench has a depth-to-width ratio of 16:1 to 20:1; and / or the third trench has a depth-to-width ratio of 16:1 to 20:

1.

15. A semiconductor structure, characterized in that: The semiconductor structure is formed by the semiconductor structure forming method according to any one of claims 1 to 14, the semiconductor structure includes a plurality of active areas divided by the second trench and the third trench and a plurality of connection areas connected between the second trench and the third trench, the second trench, the third trench and the connection area are all provided with a filling layer; the active area includes a first side wall and a second side wall arranged opposite to each other, the first side wall and the second side wall are arranged in parallel, and the first side wall and the second side wall both extend in a direction perpendicular to the bottom surface of the substrate; the aspect ratio of the second trench is 16:1~20:1; and / or the aspect ratio of the third trench is 16:1~20:1.

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