A patterning method

Abstract

The application provides a patterning method, which is applied to the technical field of semiconductors. In the application, the pattern density in the first area is increased by adding a mask layer, so that the purpose of avoiding the collapse of the sidewall layer is achieved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a patterning method. Background Art

[0002] As various electronic products develop towards miniaturization, semiconductor device design must also meet the requirements of high integration and high density. Dynamic random access memory (DRAM) with a recessed gate structure has gradually replaced DRAM with only a planar gate structure in the current mainstream development trend because it can achieve a longer carrier channel length within the same semiconductor substrate, thereby reducing leakage in the capacitor structure. Generally speaking, a DRAM with a recessed gate structure is composed of a large number of memory cells clustered together to form an array area for storing information. Each memory cell is composed of a transistor element and a capacitor element connected in series to receive voltage information from a wordline (WL) and a bitline (BL). To meet product requirements, the density of memory cells in the array area must continue to increase, resulting in increasing difficulty and complexity in the related manufacturing process and design. Therefore, existing technologies or structures need to be further improved to effectively enhance the performance and reliability of related memory devices. Summary of the Invention

[0003] The object of the present invention is to provide a patterning method, which increases the pattern density in the first area by adding a third mask layer between some adjacent sidewall layers and extending the coverage area of ​​the second photoresist layer laterally from the second area to the first area, so as to avoid the collapse of the sidewall layer in the first area during the etching process.

[0004] To solve the above technical problems, the present invention provides a patterning method, which may at least include:

[0005] providing a substrate comprising a first region and a second region;

[0006] forming a first mask layer on the first region and the second region;

[0007] forming a plurality of mutually spaced columnar mask structures on the first mask layer in the first region, wherein the columnar mask structures include a second mask layer and a third mask layer stacked sequentially from bottom to top;

[0008] forming a sidewall layer to cover the columnar mask structure and the substrate;

[0009] forming a first photoresist layer covering the sidewall layer on the substrate in the second region;

[0010] removing the sidewall layer on the top surface of the columnar mask structure and the sidewall layer on the substrate in the first region;

[0011] removing the third mask layer in the columnar mask structure;

[0012] forming a second photoresist layer having an opening on the first region and the second region, wherein the opening exposes a portion of the columnar mask structure in the first region, and the second photoresist layer covers a portion of the columnar mask structure and a portion of the sidewall layer in the first region, and the substrate and the first mask layer in the second region;

[0013] Using the second photoresist layer as a mask, the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder are removed.

[0014] Optionally, during the process of removing the third mask layer in the columnar mask structure, the first mask layer on the first region close to the second region may also be removed simultaneously to form a groove.

[0015] Optionally, during the process of removing the third mask layer in the columnar mask structure, the sidewall layer on the second region may also be removed simultaneously.

[0016] Optionally, in the process of removing the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder using the second photoresist layer as a mask, the first mask layer between adjacent columnar mask structures may also be removed simultaneously.

[0017] Optionally, the patterning method may further include:

[0018] The second photoresist layer and the second mask layer in the columnar mask structure on the first region shielded by the second photoresist layer are removed.

[0019] Optionally, the patterning method may further include:

[0020] Part of the height of the substrate is etched using the remaining sidewall layer on the first region and the second region and the first mask layer as mask layers to form a plurality of trenches and active regions defined by the trenches on the substrate.

[0021] Optionally, the groove may include a first groove and a second groove, and the second groove may be aligned with the groove.

[0022] Optionally, the bottom surfaces of the first groove and the second groove may be located at different levels.

[0023] Optionally, after forming the plurality of trenches, the method may further include: filling the trenches with an insulating layer.

[0024] Optionally, the step of forming a second photoresist layer having an opening on the first region and the second region may further include:

[0025] The second photoresist layer is formed to simultaneously cover at least one of the columnar mask structures and the sidewall layers on both side walls thereof, and the sidewall layer on one side wall of another columnar mask structure adjacent to the at least one columnar mask structure, and the opening exposes the other columnar mask structure and the sidewall layer on the other side wall of the other columnar mask structure.

[0026] In the present invention, the columnar mask structure formed in the first region is configured as a film layer structure comprising two stacked mask layers, so that after a sidewall layer is formed on the sidewall of the columnar mask structure, the second mask layer in the columnar mask structure can be utilized to increase the pattern density in the first region and reduce the aspect ratio of the gaps contained therein, thereby avoiding the problem of collapse of the sidewall layer due to excessive stress when a self-aligned patterning process is performed using the sidewall layer as a mask due to the high aspect ratio between the sidewall layers in the first region. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the present application but do not constitute a limitation of the present application. In the accompanying drawings:

[0028] Figure 1 is a flow chart of a patterning method provided in one embodiment of the present invention;

[0029] Figures 2 to 9 Schematic diagram of the structure of the patterning method provided in one embodiment of the present invention during the preparation process.

[0030] Wherein, the accompanying drawings are marked as follows:

[0031] 100-substrate, 100A-first region, 100B-second region, 110-isolation layer, 120-first mask layer, 131-second mask layer, 132-third mask layer, 130-columnar mask structure, 140-sidewall layer, 150-first photoresist layer, 140'-sidewall layer remaining after etching, 120'-first mask layer remaining on the second region, 101-recess, 160-second photoresist layer, 102-opening, 103-groove, 103a-first groove, 103b-second groove.

[0032] In the drawings, like components are given like reference numerals, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0033] In order to make the technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Although the accompanying drawings show exemplary implementation methods of the present invention, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0034] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in illustrating the purpose of the embodiments of the present invention. It will be understood that the meanings of "on...", "above..." and "above..." in the present invention should be interpreted in the broadest way, so that "on..." not only means that it is "on" something and there are no intervening features or layers (i.e., directly on something), but also includes the meaning of being "on" something and having intervening features or layers.

[0035] For ease of understanding, a horizontal direction and a vertical direction are defined below, wherein the horizontal direction is a direction parallel to the surface of the substrate 100 ; and the vertical direction is a direction perpendicular to the surface of the substrate 100 .

[0036] See also Figure 1 , Figure 1 FIG. 1 is a flow chart of a patterning method provided in an embodiment of the present invention. Figure 1 As shown, the patterning method provided in this embodiment includes at least the following steps:

[0037] Step S101, providing a substrate, including a first area and a second area;

[0038] Step S102, forming a first mask layer on the first region and the second region;

[0039] Step S103, forming a plurality of mutually separated columnar mask structures on the first mask layer in the first region, wherein the columnar mask structures include a second mask layer and a third mask layer stacked sequentially from bottom to top;

[0040] Step S104, forming a sidewall layer to cover the columnar mask structure and the substrate;

[0041] Step S105 , forming a first photoresist layer to cover the sidewall layer on the substrate in the second region;

[0042] Step S106 , removing the sidewall layer on the top surface of the columnar mask structure and the sidewall layer on the substrate in the first region;

[0043] Step S107, removing the third mask layer in the columnar mask structure;

[0044] Step S108, forming a second photoresist layer having an opening on the first region and the second region, wherein the opening exposes a portion of the columnar mask structure in the first region, and the second photoresist layer covers a portion of the columnar mask structure and a portion of the sidewall layer in the first region, and the substrate and the first mask layer in the second region;

[0045] Step S109 : Using the second photoresist layer as a mask, remove the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder.

[0046] In order to enable a person skilled in the art to which the present invention pertains to easily understand the patterning method in the embodiments of the present invention, the patterning method proposed in the present invention will be further described below in conjunction with various structural diagrams of the patterning method during the preparation process. Figures 2 to 9 Schematic diagram of the structure of the patterning method provided in an embodiment of the present invention during the preparation process.

[0047] Execute the above step S101: Please refer to Figure 2 A substrate 100 is provided. The substrate 100 includes a first region 100A and a second region 100B. The first region 100A is, for example, a cell region of a semiconductor memory device, and the second region 100B is, for example, a periphery region of the semiconductor memory device. In one embodiment, the substrate 100 is made of any suitable substrate material known in the art, such as, but not limited to, a silicon substrate, a silicon-containing substrate, a silicon-on-insulator substrate, or other suitable materials.

[0048] Execute the above steps S102 and S103: Please continue to refer to Figure 2, first, using at least one of a deposition process such as physical vapor deposition, chemical vapor deposition, and atomic layer deposition, a stacked isolation layer 110 and a first mask layer 120 are sequentially formed on the surface of the entire substrate 100 in the first region 100A and the second region 100B. In one embodiment, the isolation layer 110 may be a single-layer structure, such as a silicon oxide layer or a silicon nitride layer, or a composite layer, such as an ONO composite layer composed of a first oxide layer (such as silicon dioxide), a second nitride layer (such as silicon nitride), and a third oxide layer (such as silicon dioxide) stacked in sequence from bottom to top, but the present invention is not limited to this. The material of the first mask layer 120 may include silicon oxide, amorphous silicon, polycrystalline silicon, or a combination of the above materials, but the present invention is not limited to this.

[0049] Execute the above step S103: Please continue to refer to Figure 2 , then, a deposition process is again used to sequentially form corresponding material layers of a second mask layer 131 and a third mask layer 132 on the first mask layer 120 of the first and second regions 100A and 100B, and then an etching process, such as at least one of a dry etching process and a wet etching process, is used to etch away a portion of the stacked material layers of the third mask layer 132 and the second mask layer 131, so as to form at least one discrete columnar mask structure 130 on the first mask layer 120 of the first region 100A; in an embodiment of the present invention, each of the columnar mask structures 130 may include a second mask layer 131 and a third mask layer 132 sequentially arranged from bottom to top, as shown in FIG. Figure 2 As shown, Figure 2 Three columnar mask structures 130 separated from each other are shown as an example, but the present invention is not limited to this; the materials of the second mask layer 131 and the third mask layer 132 may be different. For example, the material of the second mask layer 131 may include silicon oxide, amorphous silicon, polycrystalline silicon or a combination of the above materials (which may be the same as the material of the first mask layer 120), and the material of the third mask layer 132 may include amorphous carbon (APF), but the present invention is not limited to this.

[0050] Execute the above step S104: Please refer to Figure 3 , a sidewall layer 140 is formed on the outer surface of the columnar mask structure 130 by a deposition process; wherein the outer surface of the columnar mask structure 130 includes a top surface and a sidewall, and the sidewall layer 140 also extends to cover the top surface of the second mask layer 120 exposed between adjacent columnar mask structures 130 and the top surface of the second mask layer 120 exposed on the second area 100B, that is, forming a conformal covering Figure 2The structure of the sidewall layer 140 on the substrate 100 is shown with a plurality of discrete pillar-shaped mask structures 130. In one embodiment, the material of the sidewall layer 140 may include a dielectric material such as silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide nitride (SiCN), or a combination thereof, but is not limited thereto. Exemplarily, the material of the sidewall layer 140 is silicon oxide (SiO2).

[0051] Execute the above step S105: Please continue to refer to Figure 3 Then, a deposition process is used again to form a first photoresist layer 150 on the top surface of the sidewall layer 140 of the second area 100B to shield the corresponding structure of the second area 100B. That is, the first photoresist layer 150 exposes all film layer structures on the first area 100A, such as the sidewall layer 140.

[0052] Execute the above step S106: Please refer to Figure 4 , using an etching process such as a dry etching process, the sidewall layer 140 located on the top surface of each of the columnar mask structures 130 in the first area 100A is removed to expose the third mask layer 132 located at the top of the columnar mask structure 130. Exemplarily, in an embodiment of the present invention, the sidewall layer remaining on the sidewall of each of the columnar mask structures 130 after etching in this step is identified by the reference numeral 140'. Furthermore, since the first region 100A is not covered with the photoresist layer, i.e., the first photoresist layer 150, during the present step, the sidewall layer 140 on the top surface of the columnar mask structure 130 in the first region 100A is removed by the etching process. Furthermore, the sidewall layer 140 on the top surface of the second mask layer 120 between adjacent columnar mask structures 130 in the first region 100A and on the top surface of the second mask layer 120 near the second region 100B in the first region 100A are also removed simultaneously, thereby exposing the first mask layer 120 in the first region 100A except for the corresponding regions where the columnar mask structures 130 and the sidewall layers 140′ on their sidewalls are removed.

[0053] It should be understood that, since the first photoresist layer 150 is formed on the second region 100B in this step, a sidewall layer still remains on the second region 100B after step S106 is performed. For a unified description, the sidewall layer remaining on the second region 100B is also identified by reference numeral 140′ in the embodiment of the present invention, but the present invention is not limited thereto.

[0054] Execute the above step S107: Please refer to Figure 5The first photoresist layer 150 located on the second region 100B can be removed first. Then, an etching process can be used to selectively remove the third mask layer 132 located at the top of each pillar-shaped mask structure 130 in the first region 100A and the exposed first mask layer 120 located on the first region 100A and adjacent to the second region 100B, based on the different etching selectivities between different materials, thereby forming a recess 101 in the first region 100A. In this embodiment of the present invention, the first mask layer remaining on the second region 100B after this step is illustratively labeled 120'. It should be understood that, since no photoresist layer is formed on the second region 100B during this step, the sidewall layer 140' on the second region 100B can also be removed simultaneously during the formation of the recess 101.

[0055] Obviously, after executing the above-mentioned steps S101 to S107 in the embodiment of the present invention, at least the second mask layer 131 is provided between each pair of adjacent sidewall layers 104'. Therefore, when a subsequent self-aligned patterning process is performed based on the sidewall layer 140', such as a self-aligned reverse patterning process (SARP) for subsequent structure formation, the second mask layer 131 can be used to increase the pattern density in the first region 100A and reduce the aspect ratio of the gap between adjacent sidewall layers 140', thereby avoiding the problem of collapse of the sidewall layer 140' due to the high aspect ratio of the gap between the adjacent sidewall layers 104' during the subsequent etching process.

[0056] Execute the above step S108: Please refer to Figure 6a A second photoresist layer 160 is formed over a portion of the first region 100A and the entire second region 100B. The second photoresist layer 160 has an opening 102 therein, and the opening 102 exposes a portion of the columnar mask structure 130 in the first region 100A (after the third mask layer 132 has been removed). In this configuration, the second photoresist layer 160 in this embodiment of the present invention not only covers the film structure in the second region 100B but also extends to cover a portion of the film structure in the first region 100A. Furthermore, the number and size of active areas and trenches subsequently formed in the first region 100A can be adjusted based on the amount of film structure, such as the columnar mask structure 130 and / or the sidewall layer 140', in the first region 100A that is shielded by the second photoresist layer 160.

[0057] It should be understood that in order to distinguish between a plurality of different columnar mask structures 130, Figure 6a and Figure 6b The plurality of columnar mask structures 130 are respectively identified by reference numerals “130a, 130b, ..., 130d, etc.”; Figure 6aAs shown, the second photoresist layer 160 can also simultaneously cover a columnar mask structure 130a and the sidewall layers 140' on both side walls thereof, and the sidewall layer 140' on one side wall of another columnar mask structure 130b adjacent to the columnar mask structure 130a, and the opening 102 of the second photoresist layer 160 can expose the other columnar mask structure 130b and the sidewall layer 140' on the other side wall of the other columnar mask structure 130b. Figure 6b As shown, Figure 6b In one embodiment of the present invention, Figure 6a The second photoresist layer 160 shields the first region 100A by different numbers of film structures; Figure 6b As shown, in another embodiment, the second photoresist layer 160 may also simultaneously cover two or more of the columnar mask structures 130 and the sidewall layers 140' on both side walls thereof (for example, the columnar mask structure 130a and the columnar mask structure 130b and the sidewall layers 140' on both sides thereof), and the sidewall layer 140' on one side wall of another columnar mask structure 130 adjacent to the columnar mask structure 130 (for example, the sidewall layer 140' on one side wall of the columnar mask structure 130c), and the opening 102 of the second photoresist layer 160 may expose another columnar mask structure 130 and the sidewall layer 140' on the other side wall of the other columnar mask structure 130 (for example, the columnar mask structure 130c and the sidewall layer 140' on the other side wall thereof), but the present invention is not limited thereto.

[0058] Execute the above step S109: Please refer to Figure 7 Using the second photoresist layer 160 as a mask, the second mask layer 131 in the columnar mask structure 130 corresponding to the opening 102 and the first mask layer 120 thereunder and the first mask layer 120 between adjacent columnar mask structures 130 are selectively removed in a vertical direction along the opening 102 to expose the isolation layer 110 between adjacent sidewall layers 140'; subsequently, the second photoresist layer 160 can be removed.

[0059] Continue with step S109: Please refer to Figure 8Then, the second mask layer 131 in the columnar mask structure 130 in the first region 100A that is shielded by the second photoresist layer 160 formed previously can be further removed (exposed as the second photoresist layer 160 is removed) to expose the sidewall layer 140' and the first mask layer 120' that are covered by the second photoresist layer 160 and not removed in the above step S108. Obviously, since this step removes the second photoresist layer 160 in the columnar mask structure 130 that is shielded by the second photoresist layer 160 formed previously, After the second mask layer 131 is removed, the exposed sidewall layer 140' and the first mask layer 120' are shielded by the second photoresist layer 160 during the above-mentioned steps. That is, the first mask layer 120' between the exposed sidewall layer 140' is retained. Therefore, it is retained even after only the second mask layer 131 is removed. This results in a different structure from the sidewall layer 140' and the first mask layer 120' remaining after the removal of the second mask layer 131, which are exposed by the opening 102 of the second photoresist layer 160. It should be understood that, for the sake of uniform description, in the present embodiment of the present invention, the first mask layer that does not completely cover the isolation layer 110 after the removal process is performed is labeled with the reference numeral 120', but this is not limiting.

[0060] Continue with step S109: Please refer to Figure 9 Then, using the remaining sidewall layer 140' and the first mask layer 120 on the first region 100A and the second region 100B as a mask layer, a portion of the height of the substrate 100 is vertically etched downward to form a plurality of trenches 103 and active areas defined by the trenches 103 on the substrate 100. The trenches 103 are then filled with an insulating material, such as an oxide or nitride, to form trench isolation structures defining the active areas. Specifically, the trenches 103 can be configured as first trenches 103a and second trenches 103b based on their horizontal widths. The second trench 103b is aligned with the recess 101, and the horizontal width of the first trench 103a can be smaller than the horizontal width of the second trench 103b, but is not limited thereto. Furthermore, the bottom surfaces of the first trench 103a and the second trench 103b may be located at different levels. For example, the bottom surface of the first trench 103a may be higher than the bottom surface of the second trench 103b, but the present invention is not limited thereto.

[0061] To summarize, in the present invention, the columnar mask structure formed in the first region is configured as a film layer structure comprising two stacked mask layers, so that after a sidewall layer is formed on the sidewall of the columnar mask structure, the second mask layer in the columnar mask structure can be utilized to increase the pattern density in the first region and reduce the aspect ratio of the gaps contained therein, thereby avoiding the problem of collapse of the sidewall layer due to excessive stress when a self-aligned patterning process is performed using the sidewall layer as a mask due to the high aspect ratio between the sidewall layers in the first region.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A patterning method, characterized in that: include: providing a substrate comprising a first region and a second region; forming a first mask layer on the first region and the second region; forming a plurality of mutually spaced columnar mask structures on the first mask layer in the first region, wherein the columnar mask structures include a second mask layer and a third mask layer stacked sequentially from bottom to top; forming a sidewall layer to cover the columnar mask structure and the substrate; forming a first photoresist layer covering the sidewall layer on the substrate in the second region; removing the sidewall layer on the top surface of the columnar mask structure and the sidewall layer on the substrate in the first region; removing the third mask layer in the columnar mask structure; forming a second photoresist layer having an opening on the first region and the second region, wherein the opening exposes a portion of the columnar mask structure in the first region, and the second photoresist layer covers a portion of the columnar mask structure and a portion of the sidewall layer in the first region, and the substrate and the first mask layer in the second region; Using the second photoresist layer as a mask, the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder are removed.

2. The patterning method according to claim 1, wherein During the process of removing the third mask layer in the columnar mask structure, the first mask layer on the first region close to the second region is also removed simultaneously to form a groove.

3. The patterning method according to claim 1, wherein: During the process of removing the third mask layer in the columnar mask structure, the sidewall layer on the second region is also removed simultaneously.

4. The patterning method according to claim 2, wherein: In the process of removing the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder using the second photoresist layer as a mask, the first mask layer between adjacent columnar mask structures is also removed simultaneously.

5. The patterning method according to claim 4, wherein: Also includes: The second photoresist layer and the second mask layer in the columnar mask structure on the first region shielded by the second photoresist layer are removed.

6. The patterning method according to claim 5, wherein: Also includes: Part of the height of the substrate is etched using the remaining sidewall layer on the first region and the second region and the first mask layer as mask layers to form a plurality of trenches and active regions defined by the trenches on the substrate.

7. The patterning method according to claim 6, wherein: The grooves include a first groove and a second groove, and the second grooves are located in the groove.

8. The patterning method according to claim 7, wherein: The bottom surfaces of the first groove and the second groove are located at different levels.

9. The patterning method according to claim 6, wherein: After forming the plurality of trenches, the method further includes: filling the trenches with an insulating layer.

10. The patterning method according to claim 1, wherein: The step of forming a second photoresist layer having an opening on the first region and the second region further includes: The second photoresist layer is formed to simultaneously cover at least one of the columnar mask structures and the sidewall layers on both side walls thereof, and the sidewall layer on one side wall of another columnar mask structure adjacent to the at least one columnar mask structure, and the opening exposes the other columnar mask structure and the sidewall layer on the other side wall of the other columnar mask structure.

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