Patterning method

Abstract

The invention provides a patterning method which is applied to the technical field of semiconductors. According to the invention, the mask layer is additionally arranged, so that the purpose of increasing the pattern density in the first region and further preventing the side wall layer from collapsing 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, the design of semiconductor devices must also meet the requirements of high integration and high density. For dynamic random access memory (DRAM) with a recessed gate structure, since it can obtain a longer carrier channel length in the same semiconductor substrate to reduce the leakage of the capacitor structure, it has gradually replaced the dynamic random access memory with only a planar gate structure under the current mainstream development trend. Generally speaking, a dynamic random access memory with a recessed gate structure is composed of a large number of memory cells gathered to form an array area for storing information, and each memory cell can be composed of a transistor component and a capacitor component connected in series to receive voltage information from a word line (WL) and a bit line (BL). In response to product requirements, the density of memory cells in the array area must be continuously improved, resulting in increasing difficulty and complexity in related manufacturing processes and designs. Therefore, the existing technology or structure needs to be further improved to effectively improve 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 part of 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] In order 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 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 sequentially stacked 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] The second photoresist layer is used as a mask to remove the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder.

[0014] Optionally, in 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, in 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 by 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] A partial 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 grooves, the method may further include: filling an insulating layer in the grooves.

[0024] Optionally, the step of forming a second photoresist layer having an opening located 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, by setting the columnar mask structure formed in the first area as a film layer structure including two stacked mask layers, after forming a sidewall layer on the sidewall of the columnar mask structure, the second mask layer in the columnar mask structure can be used to increase the pattern density in the first area and reduce the aspect ratio of the gaps contained therein, thereby achieving the purpose of avoiding the problem of collapse of the sidewall layer due to excessive stress when the 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 area. 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 specific embodiments, they are used to explain the present application but do not constitute a limitation to 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] Figure 2 to Figure 9 It is a structural schematic diagram 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, the same reference numerals are used for the same components, 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 clearer, the technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Although the exemplary implementation methods of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the implementation methods described here. On the contrary, these implementation methods are provided in order 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 according to the following description and claims. It should be noted that the accompanying drawings are all in very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It is 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 at least includes 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 structure comprises a second mask layer and a third mask layer sequentially stacked 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, removing 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 belongs to easily understand the patterning method in the embodiment of the present invention, the patterning method proposed in the present invention will be further described below in conjunction with various structural schematic diagrams of the patterning method during the preparation process. Figure 2 to Figure 9 It is a 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; wherein the first region 100A is, for example, a storage region (cell region) of a semiconductor memory, and the second region 100B is, for example, a peripheral region (periphery region) of a semiconductor memory. In one embodiment, the substrate 100 is any suitable substrate material known in the art, such as a silicon substrate, a silicon-containing substrate, a silicon-on-insulator substrate, or a substrate composed of other suitable materials, etc., but is not limited thereto.

[0048] Execute the above steps S102 and S103: Please continue to refer to Figure 2, first, using at least one of deposition processes such as physical vapor deposition, chemical vapor deposition, atomic layer deposition, etc., 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 area 100A and the second area 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 (material such as silicon dioxide), a second nitride layer (material such as silicon nitride) and a third oxide layer (material such as silicon dioxide) stacked in sequence from bottom to top, but 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 not limited to this.

[0049] Execute the above step S103: Please continue to refer to Figure 2 , then the deposition process is used again to sequentially form the corresponding material layers of the second mask layer 131 and the third mask layer 132 on the first mask layer 120 of the first area 100A and the second area 100B, and then the etching process, such as at least one of a dry etching process or a wet etching process, is used to etch away part of the stacked material layers of the third mask layer 132 and the second mask layer 131 to form at least one discrete columnar mask structure 130 on the first mask layer 120 of the first area 100A; in the embodiment of the present invention, each of the columnar mask structures 130 may include the second mask layer 131 and the third mask layer 132 arranged in sequence from bottom to top, such as 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, a conformal covering is formed on Figure 2The structure of the sidewall layer 140 on the substrate 100 having a plurality of discrete columnar mask structures 130 is shown. 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, the embodiment of the present invention identifies the sidewall layer remaining on the sidewall of each of the columnar mask structures 130 after etching in this step with the reference mark 140'. Furthermore, since the first region 100A is not covered with a photoresist layer, i.e., the first photoresist layer 150, when performing this step, in the process of removing the sidewall layer 140 on the top surface of the columnar mask structure 130 in the first region 100A by an etching process in this step, 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 to expose the first mask layer 120 outside the corresponding area of ​​the first region 100A except for the columnar mask structure 130 and the sidewall layer 140' on the sidewall.

[0053] It should be understood that, since the first photoresist layer 150 is formed on the second area 100B in this step, after executing step S106, the sidewall layer still remains on the second area 100B. For unified description, the embodiment of the present invention also uses the figure mark 140' to identify the sidewall layer remaining on the second area 100B, but is not limited to this.

[0054] Execute the above step S107: Please refer to Figure 5, the first photoresist layer 150 located on the second area 100B can be removed first, and then the third mask layer 132 located at the top of each of the columnar mask structures 130 in the first area 100A and the exposed first mask layer 120 on the first area 100A and close to the second area 100B can be selectively removed by an etching process based on the different etching selectivity characteristics between different materials, so as to form a groove 101 on the first area 100A. In the embodiment of the present invention, the first mask layer remaining on the second area 100B after this step is exemplarily marked with the reference numeral 120'. It should be understood that since no photoresist layer is formed on the second area 100B during the execution of this step, the sidewall layer 140' on the second area 100B can also be removed simultaneously during the process of forming the groove 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 arranged between the pairs 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 area 100A and reduce the aspect ratio of the gap between the 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' when performing the subsequent etching process.

[0056] Execute the above step S108: Please refer to Figure 6a , a second photoresist layer 160 is formed on a partial area of ​​the first area 100A and the entire area of ​​the second area 100B, wherein the second photoresist layer 160 has an opening 102 therein, and the opening 102 can expose a portion of the columnar mask structure 130 on the first area 100A (after the third mask layer 132 is removed). Under this setting, the second photoresist layer 160 in the embodiment of the present invention not only covers the film structure of the second area 100B, but also extends to cover a portion of the film structure on the first area 100A, and further, according to the amount of the film structure on the first area 100A, such as the columnar mask structure 130 and / or the sidewall layer 140', which is shielded by the second photoresist layer 160, the number and size of the active area and the trench formed subsequently in the first area 100A can be adjusted.

[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 another columnar mask structure 130b and the sidewall layer 140' on the other side wall of the other columnar mask structure 130b. Please refer to 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 in different numbers; 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, it may cover 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 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 above: Please refer to Figure 8Then, the second mask layer 131 in the columnar mask structure 130 shielded by the second photoresist layer 160 formed previously in the first area 100A 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' 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 shielded by the second photoresist layer 160 formed previously, After the second mask layer 131 is formed, the exposed sidewall layer 140' and the first mask layer 120' are shielded by the second photoresist layer 160 during the above steps, that is, the first mask layer 120' between the exposed sidewall layer 140' is retained, so it is also retained after only the second mask layer 131 is removed this time, thereby making it different from the film layer structure exposed by the opening 102 of the second photoresist layer 160 after removing the second mask layer 131. It should be understood that for the sake of unified description, in the 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 marked with the reference numeral 120', but it is not limited to this.

[0060] Continue with step S109 above: Please refer to Fig. 9 , then, using the remaining sidewall layer 140' and the first mask layer 120 on the first area 100A and the second area 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 an active area defined by the trenches 103 on the substrate 100, and then, an insulating material such as oxide or nitride is filled in the trenches 103 to form a trench isolation structure defining the active area. Specifically, the trench 103 can be set as a first trench 103a and a second trench 103b according to its width in the horizontal direction, wherein the second trench 103b is located opposite to the recess 101, and the width of the first trench 103a in the horizontal direction can be smaller than the width of the second trench 103b in the horizontal direction, but is not limited thereto. Furthermore, the bottom surfaces of the first groove 103a and the second groove 103b may be located at different levels. For example, the bottom surface of the first groove 103a may be higher than the bottom surface of the second groove 103b, but the present invention is not limited thereto.

[0061] To summarize, in the present invention, by setting the columnar mask structure formed in the first zone to a film layer structure comprising two stacked mask layers, 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 used to increase the pattern density in the first zone 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 the 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 zone.

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

Claims

1. A patterning method, characterized in that: include: providing a substrate including 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 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 sequentially stacked 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; The second photoresist layer is used as a mask to remove the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder.

2. The patterning method according to claim 1, characterized in that In the process of removing the third mask layer in the columnar mask structure, the first mask layer on the first area close to the second area is also removed synchronously to form a groove.

3. The patterning method according to claim 1, characterized in that In the process of removing the third mask layer in the columnar mask structure, the sidewall layer on the second region is also removed synchronously.

4. The patterning method according to claim 1, characterized in that: In the process of removing the second mask layer in the columnar mask structure corresponding to the opening and the first mask layer thereunder by using the second photoresist layer as a mask, the first mask layer between adjacent columnar mask structures is also removed synchronously.

5. The patterning method according to claim 4, characterized in that: 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, characterized in that: Also includes: A partial 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, characterized in that: The grooves include a first groove and a second groove, and the second groove is located in the groove.

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

9. The patterning method according to claim 6, characterized in that: 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.

Images