Method for manufacturing a mask structure, and method for manufacturing a semiconductor device

Abstract

The embodiment of the present disclosure provides a preparation method of a mask structure, which comprises the following steps: providing a substrate, wherein the substrate comprises a first region and a second region; forming a pattern transfer layer, a first mask layer and a second mask layer on the substrate; forming a plurality of first patterns in the second mask layer of the first region, wherein a first groove is formed between adjacent first patterns; forming a first sacrificial layer; forming a first backfill layer; removing the first backfill layer on the top surface of the first pattern, and etching downward along the first sacrificial layer on the sidewall of the first pattern, so as to form a plurality of second patterns in the first mask layer of the first region, wherein a second groove is formed between adjacent second patterns; forming a second sacrificial layer; forming a second backfill layer; removing the second backfill layer on the top surface of the second pattern, and etching downward along the second sacrificial layer on the sidewall of the second pattern, so as to form a plurality of third patterns in the pattern transfer layer on the first region.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing, and in particular to a method for fabricating a mask structure and a method for fabricating a semiconductor device. Background Technology

[0002] With the continuous development of semiconductor technology, the size of semiconductor devices is gradually decreasing. In order to improve the integration of semiconductor devices, reverse self-aligned quadruple patterning (R-SAQP) process is usually used to form patterns on semiconductor devices.

[0003] R-SAQP technology can improve the integration density of semiconductor devices, with a particularly significant advantage in reducing the size of semiconductor devices. However, in its implementation, how to further improve the reliability of the product process has become a bottleneck restricting the development of product performance. Summary of the Invention

[0004] In view of the above, this disclosure provides a method for fabricating a mask structure and a method for fabricating a semiconductor device to solve at least one problem existing in the prior art.

[0005] To achieve the above objectives, the technical solution of this disclosure embodiment is implemented as follows:

[0006] A first aspect of this disclosure provides a method for preparing a mask structure, the method comprising:

[0007] A substrate is provided, the substrate comprising a first region and a second region;

[0008] A pattern transfer layer, a first mask layer, and a second mask layer are formed on the substrate in a stacked manner from bottom to top;

[0009] The second mask layer is patterned to form a plurality of first patterns in the second mask layer on the first region, with first grooves between adjacent first patterns;

[0010] A first sacrificial layer is formed, which covers the surfaces of the first pattern and the first trench, as well as the surface of the second mask layer on the second region.

[0011] A first backfill layer is formed, which fills the first trench and covers the top surface of the first sacrificial layer.

[0012] The first backfill layer located on the top surface of the first pattern is removed, and the first sacrificial layer located on the sidewall of the first pattern is etched downward to form a plurality of second patterns in the first mask layer on the first region, with a second trench between adjacent second patterns.

[0013] A second sacrificial layer is formed, which covers the surfaces of the second pattern and the second trench, as well as the surface of the first mask layer on the second region.

[0014] A second backfill layer is formed, which fills the second trench and covers the top surface of the second sacrificial layer;

[0015] The second backfill layer located on the top surface of the second pattern is removed, and the second sacrificial layer located on the sidewall of the second pattern is etched downwards to form a plurality of third patterns in the pattern transfer layer on the first region.

[0016] According to one embodiment of this disclosure, patterning the second mask layer includes: forming a photoresist layer in the first region and the second region; patterning the photoresist layer in the first region while retaining the photoresist layer in the second region to form a patterned photoresist layer in the first region; etching the second mask layer using the patterned photoresist layer in the first region to form the plurality of first patterns in the second mask layer in the first region; and removing the patterned photoresist layer in the first region and the photoresist layer in the second region.

[0017] According to one embodiment of the present disclosure, forming the first backfill layer includes: depositing and forming the first backfill layer in the first region and the second region; the first backfill layer fills the first trench and covers the first sacrificial layer in the first region and the second region; the top of the first backfill layer in the first region is lower than the top of the first backfill layer in the second region.

[0018] According to one embodiment of this disclosure, removing the first backfill layer located on the top surface of the first pattern includes: using a planarization process to remove the first backfill layer on the top surface of the first pattern and the first backfill layer in the second region, so that the first region and the second region are flush; or using a planarization process to remove the first sacrificial layer and the first backfill layer on the top surface of the first pattern and the first backfill layer and the first sacrificial layer in the second region, so that the first region and the second region are flush.

[0019] According to one embodiment of the present disclosure, etching downward along the first sacrificial layer located on the sidewall of the first pattern to form a plurality of second patterns in the first mask layer on the first region includes: removing the first sacrificial layer on the sidewall of the first pattern to form a second initial trench exposing the first mask layer; and etching the first mask layer using the second initial trench to form a plurality of second patterns in the first mask layer on the first region.

[0020] According to one embodiment of this disclosure, the first backfill layer and the second mask layer are made of the same material, and the second mask layer and the first sacrificial layer are made of different materials.

[0021] According to one embodiment of the present disclosure, the first mask layer includes a first sub-mask layer and a first stop layer, and the second mask layer includes a second sub-mask layer and a second stop layer; the first sub-mask layer and the second sub-mask layer have the same thickness.

[0022] According to one embodiment of this disclosure, etching the first mask layer using the second initial trench to form a plurality of second patterns in the first mask layer on the first region includes: etching the second stop layer and the first stop layer exposed in the first region, and the second stop layer in the second region; etching the second sub-mask layer, the first backfill layer and the first sub-mask layer exposed in the first region, and the second sub-mask layer in the second region to form a plurality of second patterns in the first mask layer on the first region; the second trench exposes the pattern transfer layer.

[0023] According to one embodiment of this disclosure, the first sacrificial layer, the second sacrificial layer, and the pattern transfer layer are made of the same material.

[0024] According to one embodiment of this disclosure, forming the second backfill layer includes: forming a second backfill layer in the first region and the second region, the second backfill layer filling the second trench and covering the second sacrificial layer in the first region and the second region; the top of the second backfill layer in the first region is lower than the top of the second backfill layer in the second region.

[0025] According to one embodiment of this disclosure, the second backfill layer and the first mask layer are made of the same material, and the first mask layer and the second sacrificial layer are made of different materials.

[0026] According to one embodiment of this disclosure, removing the second backfill layer located on the top surface of the second pattern includes: removing the second backfill layer on the top surface of the second pattern and the second backfill layer in the second region using a planarization process, so that the first region and the second region are flush; or removing the second sacrificial layer and the second backfill layer on the top surface of the second pattern and the second sacrificial layer and the second backfill layer in the second region using a planarization process, so that the first region and the second region are flush.

[0027] According to one embodiment of this disclosure, the substrate includes a third stop layer, and the pattern transfer layer is located on the third stop layer; the etching down along the second sacrificial layer located on the sidewall of the second pattern to form a plurality of third patterns in the pattern transfer layer on the first region includes: removing the second sacrificial layer on the sidewall of the second pattern to form a third initial trench exposing the pattern transfer layer; etching the pattern transfer layer using the third initial trench to form a plurality of third patterns in the pattern transfer layer on the first region; a third trench is formed between adjacent third patterns, and the third trench exposes the third stop layer.

[0028] According to one embodiment of this disclosure, the density of the plurality of second patterns is twice the density of the plurality of first patterns; the density of the plurality of third patterns is twice the density of the plurality of second patterns.

[0029] A second aspect of this disclosure provides a method for fabricating a semiconductor device, the method comprising:

[0030] A semiconductor substrate is provided, the surface of which has a layer to be etched;

[0031] The aforementioned mask structure fabrication method is used to form the plurality of third patterns on the layer to be etched;

[0032] The etching layer is etched based on the plurality of third patterns to transfer the patterns of the plurality of third patterns to the etchable layer.

[0033] According to one embodiment of this disclosure, the layer to be etched includes a metal layer.

[0034] This disclosure provides a method for fabricating a mask structure and a method for fabricating a semiconductor device. The method includes: providing a substrate, the substrate including a first region and a second region; forming a pattern transfer layer, a first mask layer, and a second mask layer stacked sequentially from bottom to top on the substrate; patterning the second mask layer, forming a plurality of first patterns in the second mask layer on the first region, with a first trench between adjacent first patterns; forming a first sacrificial layer, the first sacrificial layer covering the surfaces of the first patterns and the first trenches and the surface of the second mask layer on the second region; forming a first backfill layer, the first backfill layer filling the first trenches and covering the top surface of the first sacrificial layer; removing the structure located in the first region... The first backfill layer on the top surface of the first pattern is etched downwards along the first sacrificial layer located on the sidewall of the first pattern to form a plurality of second patterns in the first mask layer on the first region, with second trenches between adjacent second patterns; a second sacrificial layer is formed, the second sacrificial layer covering the surfaces of the second patterns and the second trenches as well as the surface of the first mask layer on the second region; a second backfill layer is formed, the second backfill layer filling the second trenches and covering the top surface of the second sacrificial layer; the second backfill layer located on the top surface of the second pattern is removed, and the second sacrificial layer located on the sidewall of the second pattern is etched downwards to form a plurality of third patterns in the pattern transfer layer on the first region.

[0035] This embodiment of the present disclosure forms a first backfill layer that fills the first trench between adjacent first patterns and covers the first sacrificial layer. After removing the first backfill layer on the top surface of the first pattern, the first sacrificial layer located on the sidewall of the first pattern is etched downwards to form a second pattern in the first mask layer of the first region. This allows the top of the first mask layer of the second region to be substantially flush with the top of the second pattern in the first region. In other words, it makes the height of the first region where a certain density of pattern is formed after performing the R-SAQP process and the second region where no pattern is formed uniform, thereby avoiding the difference in process effect between the two regions due to the height difference between the first and second regions in subsequent processes. Attached Figure Description

[0036] Figures 1a-1h This is a schematic diagram illustrating the fabrication process of a mask structure according to an embodiment of the present disclosure;

[0037] Figure 2 A schematic flowchart illustrating a method for fabricating a mask structure according to an embodiment of this disclosure;

[0038] Figures 3a-3p This is a schematic diagram illustrating the fabrication process of another mask structure provided in an embodiment of this disclosure. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0040] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without one or more of these details. In other instances, to avoid confusion with this disclosure, certain technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0041] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0042] It should be understood that spatial relation terms such as “below,” “under,” “below,” “below,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “below” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0043] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0044] Figures 1a-1hThis is a schematic diagram illustrating the fabrication process of a mask structure provided in an embodiment of this disclosure. Figure 1a As shown, the structure includes a substrate 100, and a pattern transfer layer 140 and a first mask layer 150 stacked sequentially on the substrate 100. The substrate 100 includes an etchable layer 110, a third mask layer 120, and a third stop layer 130 stacked sequentially from bottom to top. The substrate 100 includes a first region 101 and a second region 102. The desired pattern is first formed on the pattern transfer layer 140, and then transferred from the pattern transfer layer 140 to the etchable layer 110. The pattern density of the desired pattern formed on the pattern transfer layer 140 in the first region 101 is greater than the pattern density of the desired pattern formed on the pattern transfer layer 140 in the second region 102.

[0045] For example, Dynamic Random Access Memory (DRAM) typically includes an array region and a peripheral region. Due to product performance requirements, a higher density pattern needs to be formed in the array region, while a lower density pattern needs to be formed in the peripheral region. This difference in pattern density can lead to a loading effect in the process, resulting in pattern anomalies or defects at the array region boundaries. To solve this problem, this difference in pattern density is usually compensated for by setting dummy patterns. However, many areas on the DRAM (e.g., alignment marks, test pads, etc.) cannot be dummyized, thus making it impossible to compensate for the difference in pattern density. Therefore, the first region 101 can be the dummyized areas in the array region and peripheral region of the DRAM, while the second region 102 can be the dummyized areas of the DRAM.

[0046] A plurality of first patterns 260 are disposed on a first mask layer 150 in a first region 101. In some embodiments, the first patterns 260 may include a mandrel structure. The first patterns 260 include a first portion 261 and a second portion 262. Here, the plurality of first patterns 260 constitute a patterned second mask layer. A first trench 241 is provided between adjacent first patterns 260, and the first trench 241 exposes the first mask layer 150 in the first region 101. A second mask layer 160 is disposed on the first mask layer 150 in the second region 102, and the second mask layer 160 includes a second sub-mask layer 161 and a second stop layer 162. The first portion 261 of the first pattern 260 and the second sub-mask layer 161 have the same material and thickness, and the second portion 262 and the second stop layer 162 have the same material and thickness.

[0047] Here, a reverse self-aligned quadruple patterning (R-SAQP) process is used to form patterns on the pattern transfer layer 140. The R-SAQP process includes a single self-aligned double patterning (SADP) process and a single reverse self-aligned double patterning (R-SADP) process.

[0048] Figures 1b-1d This is a schematic diagram of the SADP process. Figure 1b As shown, a first sacrificial layer 170 is formed. The first sacrificial layer 170 covers the surfaces of the first pattern 260 and the first trench 241, as well as the surface of the second mask layer 160 on the second region 102.

[0049] like Figure 1c As shown, the first sacrificial layer on top of the first pattern 260 is etched away. Simultaneously with etching away the first sacrificial layer on top of the first pattern 260, the first sacrificial layer on the surface of the first trench in the first region 101 and the first sacrificial layer on the second mask layer 160 in the second region 102 are also removed. Then, the first pattern 260 is removed. Since the first pattern 260 and the second mask layer 160 have the same material and thickness, the second mask layer 160 on the second region 102 is also removed simultaneously with the removal of the first pattern 260. In the first region 101, the first sacrificial layer on the sidewalls of the first pattern 260 is retained, forming a sidewall structure 171 (spacer).

[0050] As shown in Figure c and Figure 1dAs shown, the first mask layer 150 is etched using the sidewall structure 171 as a mask to form several second patterns 250. Adjacent second patterns 250 have second trenches 242 that expose the pattern transfer layer 140 of the first region 101. Each second pattern 250 includes a first portion 251 and a second portion 252. The first mask layer 150 includes a first sub-mask layer 151 and a first stop layer 152. The first portion 251 and the first sub-mask layer 151 have the same material and thickness, as do the second portion 252 and the first stop layer 152. Therefore, while etching the first mask layer 150 of the first region 101 through the sidewall structure 171 to form the second patterns 250, the first mask layer 150 of the second region 102 is also removed, exposing the pattern transfer layer 140 of the second region 102. This results in the top of the pattern transfer layer 140 of the second region 102 being lower than the top of the second pattern 250. Therefore, in subsequent processes, the pattern transfer layer 140 of the second region 102 and some of the underlying layer structures (such as the third mask layer 120 and the etchable layer 110) may be damaged before the pattern is formed on the pattern transfer layer 140 of the first region 101.

[0051] Figures 1e-1h This is a schematic diagram of the R-SADP process. (Example) Figure 1e As shown, a second sacrificial layer 180 is formed. The second sacrificial layer 180 covers the surfaces of the second pattern 250 and the second trench 242, as well as the pattern transfer layer 140 of the second region 102. The second sacrificial layer 180 is made of the same material as the pattern transfer layer 140. In other embodiments, the second sacrificial layer 180 is made of a different material than the pattern transfer layer 140. In this case, there is a significant height difference between the first region and the second region.

[0052] like Figure 1f As shown, a backfill layer 190 is formed. The backfill layer 190 fills the spaces between the second patterns 250 and covers the pattern transfer layer 140 of the second region 102. As previously mentioned, due to the significant height difference between the first region 101 and the second region 102, the top of the backfill layer of the subsequently formed first region 101 is higher than the top of the backfill layer of the second region 102.

[0053] like Figure 1gAs shown, the second sacrificial layer, formed by etching away the top and sidewalls of the second pattern 250, forms trenches, and the pattern transfer layer continues to be etched downwards along the trenches on the sidewalls of the second pattern. During the etching of the first region 101, a portion of the layer structure of the second region 102 is also etched away. Since the top of the backfill layer in the second region 102 is lower than the top of the backfill layer in the first region 101, the third stop layer 130 and the third mask layer 120 of the second region 102 will be destroyed when the pattern transfer layer continues to be etched downwards along the trenches on the sidewalls of the second pattern.

[0054] like Figure 1h As shown, the backfill layer and the second pattern on the pattern transfer layer 140 of the first region 101 are removed. Simultaneously, a portion of the layer structure of the second region 102 is also removed. As previously mentioned, since the third stop layer 130 and the third mask layer 120 of the second region 102 have been damaged, the removal of the backfill layer and the second pattern on the pattern transfer layer 140 of the first region 101 may directly remove the thinner third mask layer on the second region 102, thereby damaging the underlying layer 110 to be etched.

[0055] Therefore, this disclosure provides a method for preparing a mask structure. Figure 2 This is a schematic flowchart illustrating a method for fabricating a mask structure according to an embodiment of the present disclosure. Figures 3a-3p This is a schematic diagram illustrating the fabrication process of another mask structure provided in an embodiment of this disclosure. The following will be combined with... Figures 3a-3p The method for fabricating the mask structure provided in the embodiments of this disclosure is described. The R-SAQP process provided in the embodiments of this disclosure includes two R-SADP processes. Figures 3a-3j This is a schematic diagram of the first R-SADP process. In step 201, a substrate is provided. (As shown...) Figure 3a As shown, a substrate 100 is provided, which includes a first region 101 and a second region 102. It should be noted that the first region 101 and the second region 102 may be adjacent or non-adjacent regions.

[0056] The substrate 100 includes, from bottom to top, a layer to be etched 110, a third mask layer 120, and a third stop layer 130, stacked sequentially. The layer to be etched may include a metal layer, the material of which includes, but is not limited to, tungsten (W). The material of the third mask layer 120 includes, but is not limited to, amorphous carbon layer (ACL), silicon oxynitride (SiON), polysilicon, or oxide. The material of the third stop layer 130 includes, but is not limited to, silicon oxynitride, silicon oxide, silicon nitride, and polysilicon.

[0057] In step 202, a pattern transfer layer, a first mask layer, and a second mask layer are formed on the substrate, stacked sequentially from bottom to top. For example... Figure 3b As shown, a pattern transfer layer 140, a first mask layer 150, and a second mask layer 160 are formed on a substrate 100, stacked sequentially from bottom to top. The pattern transfer layer 140 is made of materials including, but not limited to, oxides and polysilicon. The first mask layer 150 includes a first sub-mask layer 151 and a first stop layer 152. The first sub-mask layer 151 is made of materials including, but not limited to, spin-on hard masks (SOH), which can be formed by a spin coating process. The first stop layer 152 is made of materials including, but not limited to, silicon oxynitride, silicon oxide, silicon nitride, and polysilicon. In some embodiments, the first stop layer 152 and the third stop layer 130 are made of the same material. In practical applications, a first sub-mask layer 151 can be formed first by spin coating, and then a first stop layer 152 can be deposited on the first sub-mask layer 151 to form the first mask layer 150. For example, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced chemical vapor deposition (PECVD), sputtering, metal-organic chemical vapor deposition (MOCVD), or atomic layer deposition (ALD) can be used.

[0058] The second mask layer 160 includes a second sub-mask layer 161 and a second stop layer 162. In some embodiments, the second sub-mask layer 161 and the first sub-mask layer 151 have the same material and thickness. The second stop layer 162 and the first stop layer 152 have the same material and thickness. In practical applications, the second mask layer 160 can be formed through steps similar to those for forming the first mask layer 150, which will not be described in detail here.

[0059] In step 203, the second mask layer is patterned, forming a plurality of first patterns in the second mask layer over the first region. For example... Figure 3c As shown, a photoresist layer 210 is formed in a first region 101 and a second region 102. Then, the photoresist layer in the first region 101 is patterned while the photoresist layer in the second region is retained, to form a patterned photoresist layer 211 in the first region 101. The patterned photoresist layer 211 has an opening that exposes the second mask layer 160.

[0060] like Figure 3dAs shown, a patterned photoresist layer 211 on the first region 101 is used to etch a second mask layer 160 to form a plurality of first patterns 260 in the second mask layer of the first region 101. Here, the plurality of first patterns 260 on the first region 101 constitute a patterned second mask layer. A first trench 241 is provided between adjacent first patterns 260, and the first trench 241 exposes the first mask layer 150 of the first region 101. The first pattern 260 includes a first portion 261 and a second portion 262. The first portion 261 and the second sub-mask layer 161 have the same material and thickness, and the second portion 262 and the second stop layer 162 have the same material and thickness. Exemplarily, the patterned photoresist layer 211 can be used to perform wet etching and / or dry etching (e.g., reactive ion etching, RIE) on the second mask layer 160 to form a plurality of first patterns 260. It should be noted that the number of first patterns 260 in the figure is only used to describe the embodiments of this disclosure and is not intended to limit the number of first patterns 260. The number of first patterns 260 can be set according to actual needs. After forming a plurality of first patterns 260, the patterned photoresist layer 211 of the first region 101 and the photoresist layer 210 of the second region 102 are removed.

[0061] In step 204, the first sacrificial layer is formed. For example... Figure 3e As shown, the first sacrificial layer 170 covers the surfaces of the first pattern 260 and the first trench 241, as well as the surface of the second mask layer 160 of the second region 102. The material of the first sacrificial layer 170 includes, but is not limited to, oxides. The materials of the first sacrificial layer 170 and the second mask layer 160 are different. The first sacrificial layer 170 can be deposited using one or more thin film deposition processes, such as CVD, PVD, ALD, any other suitable process, or combinations thereof.

[0062] In step 205, the first backfill layer is formed. For example... Figure 3fAs shown, a first backfill layer 220 is deposited on a first region 101 and a second region 102. The first backfill layer 220 fills a first trench and covers a first sacrificial layer 170 of the first region 101 and the second region 102. The first region 101 has a first pattern 260, and the deposited first backfill layer first fills the first trench between the first patterns 260, such that the top of the first backfill layer in the first region 101 is lower than the top of the first backfill layer in the second region 102. The first backfill layer 220 and the second mask layer 160 are made of the same material. In some embodiments, the first backfill layer 220 and the second sub-mask layer 161 are made of the same material. In other embodiments, the first backfill layer 220 and the second stop layer 162 are made of the same material. The first backfill layer 220 can be deposited using one or more thin film deposition processes, such as CVD, PVD, ALD, any other suitable process, or combinations thereof.

[0063] In step 206, the first sacrificial layer located on the top surface of the first pattern is removed, and the first sacrificial layer located on the sidewall of the first pattern is etched downward to form a plurality of second patterns in the first mask layer on the first region.

[0064] like Figure 3f and Figure 3g As shown, the first backfill layer 220 and the first sacrificial layer 170 on the top surface of the first pattern 260, as well as the first backfill layer 220 and the first sacrificial layer 170 in the second region 102, are removed using a planarization process, so that the first region 101 and the second region 102 are flush.

[0065] In some embodiments, the first region 101 and the second region 102 can be planarized by a chemical mechanical polishing (CMP) process to remove the first backfill layer 220 and the first sacrificial layer 170 on the top surface of the first pattern 260, and the first backfill layer 220 and the first sacrificial layer 170 in the second region 102, thereby forming Figure 3g In the structure shown, in the first region of the structure, a first backfill layer 220' after planarization is filled between each of the first trenches 241, and the first backfill layer 220' after planarization is not higher than the first pattern 260. In other embodiments, the first backfill layer 220 and the first sacrificial layer 170 on the top surface of the first pattern 260, as well as the first backfill layer 220 and the first sacrificial layer 170 in the second region 102, can be removed by etch back.

[0066] In some embodiments, a planarization process can also be used to remove the first backfill layer 220 on the top surface of the first pattern 260 and the second backfill layer 220 in the second region 102. The first sacrificial layer 170 on the top surface of the first pattern 260 and the first sacrificial layer 170 in the second region 102 can be removed together in the subsequent step of removing the first sacrificial layer on the sidewall of the first pattern 260.

[0067] The first sacrificial layer is etched downwards along the sidewall of the first pattern 260 to form a plurality of second patterns in the first mask layer 150 on the first region 101. For example... Figure 3h As shown, a first sacrificial layer is removed from the sidewalls of the first pattern 260 to form a second initial trench 242' that exposes the first mask layer 150 of the first region 101. The first sacrificial layer at the bottom of the first backfill layer 220' after the planarization process is retained. The second initial trench 242' exposes the first mask layer 150. Since the second initial trench 242' is formed by removing the first sacrificial layer from the sidewalls of the first pattern 260, the number of second initial trenches 242' is twice the number of first trenches 241 between adjacent first patterns 260. In some embodiments, the first sacrificial layer from the sidewalls of the first pattern 260 can be removed using, for example, wet etching and / or dry etching.

[0068] The first mask layer 150 is etched using the second initial trench 242' to form a plurality of second patterns 250 in the first mask layer 150 on the first region 101.

[0069] Etching is performed on the second stop layer 162 and the first stop layer 152 exposed in the first region 101, and the second stop layer 162 exposed in the second region 102, thereby exposing the first sub-mask layer 151 of the first region 101 and the second sub-mask layer 161 of the second region 102, as follows. Figure 3i As shown.

[0070] The second sub-mask layer 261, the first backfill layer 220', and the first sub-mask layer 151 exposed in the first region 101, and the second sub-mask layer 161 in the second region 102 are etched to form a plurality of second patterns 250 in the first mask layer on the first region 101, such as Figure 3jAs shown. Adjacent second patterns 250 have a second trench 242, which exposes the pattern transfer layer 140 of the first region 101. In some embodiments, the second sub-mask layer 261, the first sub-mask layer 151, and the first backfill layer 220' are all made of the same material; therefore, the second sub-mask layer 261, the first backfill layer 220', and the first sub-mask layer 151 exposed in the first region 101, and the second sub-mask layer 161 of the second region 102, can be removed in the same etching process. Here, a plurality of second patterns 250 on the first region 101 constitute a patterned first mask layer. Each second pattern 250 includes a first portion 251 and a second portion 252. The first portion 251 of the second pattern 250 and the first sub-mask layer 151 are made of the same material and have the same thickness, as are the second portion 252 of the second pattern 250 and the first stop layer 152. The top of the second pattern 250 is substantially flush with the top of the first mask layer 150 of the second region 102. Since the second pattern 250 is formed by etching the second initial trench 242', the number of second trenches 242 between adjacent second patterns 250 is the same as the number of second initial trenches 242'. As mentioned above, the number of second initial trenches 242' is twice the number of first trenches 241, therefore the number of second trenches 242 is twice the number of first trenches 241, that is, the density of a plurality of second patterns 250 is twice the density of a plurality of first patterns 260. The number of second patterns 250 in the figure is only used to describe the embodiments of this disclosure and is not intended to limit the number of second patterns 250. It should be noted that a residual first sacrificial layer (not shown in the figure) may exist on some second patterns 250.

[0071] Compared to Figure 1d In the structure shown, the first mask layer of the second region 102 is removed, exposing the pattern transfer layer 140, and there is a large height difference between the first region 101 and the second region 102, that is, the top of the second pattern 250 of the first region 101 is higher than the top of the pattern transfer layer of the second region 102. Figure 3j The top of the second pattern 250 of the first region 101 of the structure formed in the process is substantially flush with the top of the first mask layer 150 of the second region 102. That is, the heights of the first region and the second region in the structure formed by the first R-SADP process of the R-SAQP process provided in this embodiment of the present disclosure are substantially uniform. This avoids the large height difference between the first region 101 and the second region 102 in subsequent processes (e.g., the second R-SADP process in the R-SAQP process) from damaging the pattern transfer layer 140 of the second region 102 and the layer structure below it before the pattern is formed on the pattern transfer layer 140 of the first region 101, thus preventing the process effects of the first region 101 and the second region 102 from being different.

[0072] In step 207, a second sacrificial layer is formed. Figures 3k-3p This is a schematic diagram of the second R-SADP process. Figure 3k As shown, a second sacrificial layer 240 is deposited in a first region 101 and a second region 102. The second sacrificial layer 240 covers the surfaces of the second pattern 250 and the second trench 242, as well as the surface of the first mask layer 150 in the second region 102. The second sacrificial layer 240 and the first mask layer 150 are made of different materials. In some embodiments, the second sacrificial layer 240, the first sacrificial layer 170, and the pattern transfer layer 140 are all made of the same material. In other embodiments, the second sacrificial layer 240 and the pattern transfer layer 140 are made of different materials. The second sacrificial layer 240 can be deposited using one or more thin-film deposition processes, such as CVD, PVD, ALD, any other suitable process, or combinations thereof.

[0073] In step 208, a second backfill layer is formed. The method for forming the second backfill layer is similar to the method for forming the first backfill layer, such as... Figure 3l As shown, a second backfill layer 230 is deposited on a first region 101 and a second region 102. The second backfill layer 230 fills a second trench and covers a second sacrificial layer 240 on the first region 101 and the second region 102. A second pattern 250 exists in the first region 101, and the deposited second backfill layer first fills the second trench between the second patterns 250, such that the top of the final second backfill layer in the first region 101 is lower than the top of the second backfill layer in the second region 102. The second backfill layer 230 is made of the same material as the first mask layer 150. In some embodiments, the second backfill layer 230 is made of the same material as the first sub-mask layer 151. In other embodiments, the second backfill layer 230 is made of the same material as the first stop layer 152. The second backfill layer 230 can be deposited using one or more thin-film deposition processes, such as CVD, PVD, ALD, any other suitable process, or combinations thereof.

[0074] In step 209, the second backfill layer located on the top surface of the second pattern is removed, and the second sacrificial layer located on the sidewall of the second pattern is etched downward to form a plurality of third patterns in the pattern transfer layer on the first region.

[0075] like Figure 3m As shown, the second backfill layer 230 and the second sacrificial layer 240 on the top surface of the second pattern 250, as well as the second backfill layer 230 and the second sacrificial layer 240 in the second region 102, are removed using a planarization process, so that the first region 101 and the second region 102 are flush.

[0076] In some embodiments, the first region 101 and the second region 102 can be planarized using a CMP process to remove the second backfill layer 230 and the second sacrificial layer 240 on the top surface of the second pattern 250, as well as the second backfill layer 230 and the second sacrificial layer 240 in the second region 102, thereby forming Figure 3m In the structure shown, in the first region of the structure, a second backfill layer 230' after planarization is filled in each of the second trenches 242, and the second backfill layer 230' after planarization is not higher than the second pattern 250. In other embodiments, the second backfill layer 230 and the second sacrificial layer 240 on the top surface of the second pattern 250, as well as the second backfill layer 230 and the second sacrificial layer 240 of the second region 102, can be removed by etching back, so that the first region 101 and the second region 102 are flush.

[0077] In some embodiments, a planarization process can also be used to remove the second backfill layer 230 on the top surface of the second pattern 250 and the second backfill layer 230 in the second region 102, so that the first region 101 and the second region 102 are flush. The second sacrificial layer 240 on the top surface of the second pattern 250 and the second sacrificial layer 240 in the second region 102 can be removed together in the subsequent step of removing the second sacrificial layer on the sidewall of the second pattern 250.

[0078] The second sacrificial layer is etched downwards along the sidewall of the second pattern 250 to form a plurality of third patterns in the pattern transfer layer 140 on the first region 101. For example... Figure 3n As shown, a second sacrificial layer is removed from the sidewalls of the second pattern 250 to form a third initial trench 243' exposing the pattern transfer layer 140 on the first region 101. Since the third initial trench 243' is formed by removing the second sacrificial layer from the sidewalls of the second pattern 250, the number of third initial trenches 243' is twice the number of second trenches 242 between adjacent second patterns 250. In some embodiments, the second sacrificial layer from the sidewalls of the second pattern 250 can be removed using, for example, wet etching and / or dry etching.

[0079] like Figure 3oAs shown, the pattern transfer layer 140 is etched using a third initial trench 243' to form a plurality of third patterns 141 in the pattern transfer layer on the first region 101. A third trench 243 is formed between adjacent third patterns 141, exposing a third stop layer 130. Since the third patterns 141 are formed by etching the third initial trench 243', the number of third trenches 243 between adjacent third patterns 141 is the same as the number of third initial trenches 243'. As mentioned earlier, the number of third initial trenches 243' is twice the number of second trenches 242, therefore the number of third trenches 243 is twice the number of second trenches 242, meaning the density of the plurality of third patterns 141 is twice the density of the plurality of second patterns 250.

[0080] like Figure 3p As shown, the second pattern 250 and the second backfill layer 230' of the first region 101, and the first mask layer 150 of the second region 102 are removed. Exemplarily, the first stop layer 152 exposed in the first region 101 and the first stop layer 152 of the second region 102 can be etched. Then, the first sub-mask layer 151 and the second backfill layer 230' exposed in the first region 101, and the first sub-mask layer 151 of the second region 102 are removed. Since the second backfill layer 230' and the first sub-mask layer 151 are made of the same material, they can be removed in the same step. In some embodiments, the second backfill layer 230' and the first sub-mask layer 151 can be removed by an ashing process (ASH).

[0081] Compared with the above Figure 1g and Figure 1h The structure shown, Figure 3p When the third pattern 141 is formed in the pattern transfer layer 140 of the first region 101, the pattern transfer layer 140 of the second region 102 and the underlying layer structure (e.g., the third mask layer 120 and the etchable layer 110) are not damaged. This disclosure utilizes an R-SAQP process comprising two R-SADP processes to form the mask structure, such that the top of the first region 101 formed by the first R-SADP process is substantially flush with the top of the second region 102. This avoids the damage to the pattern transfer layer 140 of the second region 102 and the underlying layer structure (e.g., the third mask layer 120 and the etchable layer 110) before the third pattern is formed in the pattern transfer layer 140 of the first region 101 during subsequent processes due to the large height difference between the first region 101 and the second region 102.

[0082] The mask structure fabrication method provided in this disclosure, whether performing R-SADP or R-SAQP processes, can make the first and second regions with different pattern densities highly uniform and without differences in process effects. Therefore, it is not necessary to add dummy to compensate for the differences in process effects caused by the loading effect due to the different pattern densities. Based on this, defects caused by adding dummy can be avoided.

[0083] In some embodiments, the layer 110 to be etched can be patterned by etching with a third pattern 141. Exemplarily, a third stop layer 130 can be etched using a third trench 243, and etching can continue downwards through the third mask layer 120 and the layer 110 to be etched, to form a fourth trench extending into the layer 110 to be etched. The depth of the fourth trench can be controlled by controlling the etching time and / or etching rate.

[0084] In some embodiments, the third pattern formed by the above method can be subsequently used to form an array pattern, such as a landing pad, a node contact (NC), or a buried wordline (BW).

[0085] This disclosure also provides a method for fabricating a semiconductor device, the method comprising:

[0086] A semiconductor substrate is provided, the surface of which has a layer to be etched.

[0087] Several third patterns are formed on the layer to be etched using the above-described mask structure fabrication method;

[0088] The layer to be etched is etched based on several third patterns in order to transfer the patterns of the several third patterns into the layer to be etched.

[0089] Here, several third patterns are formed in a mask layer on the layer to be etched. In other words, a mask layer with several third patterns is formed on the layer to be etched using the above-described mask structure preparation method, so that the layer to be etched is etched based on the mask layer with several third patterns, thereby transferring several third patterns to the layer to be etched.

[0090] In some embodiments, a plurality of third patterns spaced apart in different directions can be formed on the layer to be etched by using the above-described mask structure preparation method once or multiple times, and then the plurality of third patterns spaced apart in different directions can be superimposed to form a hole-like or columnar pattern.

[0091] In some embodiments, the layer to be etched includes a metal layer, the material of which includes, but is not limited to, tungsten (W).

[0092] This disclosure also provides a semiconductor device fabricated using the above-described semiconductor device fabrication method. This semiconductor device can be a memory chip, such as a DRAM chip; of course, it can also be other semiconductor devices, which will not be listed here. The beneficial effects of this semiconductor device can be referred to the beneficial effects of the mask structure fabrication method described above, and will not be repeated here.

[0093] It should be understood that the phrase "an embodiment" or "one embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this disclosure. Therefore, "in one embodiment" or "one embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this disclosure, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this disclosure. The sequence numbers of the above-described embodiments are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0094] The methods disclosed in the several method embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new method embodiments.

[0095] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for fabricating a mask structure, characterized in that, The method includes: A substrate is provided, the substrate comprising a first region and a second region; A pattern transfer layer, a first mask layer, and a second mask layer are formed on the substrate in a stacked manner from bottom to top; The second mask layer is patterned to form a plurality of first patterns in the second mask layer on the first region, with first grooves between adjacent first patterns; A first sacrificial layer is formed, which covers the surfaces of the first pattern and the first trench, as well as the surface of the second mask layer on the second region. A first backfill layer is formed, which fills the first trench and covers the top surface of the first sacrificial layer. The first backfill layer located on the top surface of the first pattern is removed, and the first sacrificial layer located on the sidewall of the first pattern is etched downward to form a plurality of second patterns in the first mask layer on the first region, with a second trench between adjacent second patterns. A second sacrificial layer is formed, which covers the surfaces of the second pattern and the second trench, as well as the surface of the first mask layer on the second region. A second backfill layer is formed, which fills the second trench and covers the top surface of the second sacrificial layer; The second backfill layer located on the top surface of the second pattern is removed, and the second sacrificial layer located on the sidewall of the second pattern is etched downwards to form a plurality of third patterns in the pattern transfer layer on the first region.

2. The method for preparing the mask structure according to claim 1, characterized in that, The patterning of the second mask layer includes: A photoresist layer is formed in the first region and the second region; The photoresist layer in the first region is patterned while the photoresist layer in the second region is retained, so as to form a patterned photoresist layer in the first region; The patterned photoresist layer on the first region is used to etch the second mask layer to form the plurality of first patterns in the second mask layer on the first region; Remove the patterned photoresist layer in the first region and the photoresist layer in the second region.

3. The method for preparing the mask structure according to claim 1, characterized in that, The formation of the first backfill layer includes: A first backfill layer is deposited in the first region and the second region; the first backfill layer fills the first trench and covers the first sacrificial layer in the first region and the second region; the top of the first backfill layer in the first region is lower than the top of the first backfill layer in the second region.

4. The method for preparing the mask structure according to claim 1, characterized in that, The removal of the first backfill layer located on the top surface of the first graphic includes: The first backfill layer on the top surface of the first pattern and the first backfill layer in the second region are removed using a planarization process to make the first region and the second region flush; or The first sacrificial layer and the first backfill layer on the top surface of the first pattern, as well as the first backfill layer and the first sacrificial layer in the second region, are removed using a planarization process to make the first region and the second region flush.

5. The method for preparing the mask structure according to claim 1, characterized in that, The etching downward along the first sacrificial layer located on the sidewall of the first pattern to form a plurality of second patterns in the first mask layer on the first region includes: Remove the first sacrificial layer from the sidewall of the first pattern to form a second initial trench that exposes the first mask layer; The first mask layer is etched using the second initial trench to form a plurality of second patterns in the first mask layer in the first region.

6. The method for preparing the mask structure according to claim 5, characterized in that, The first backfill layer and the second mask layer are made of the same material, while the second mask layer and the first sacrificial layer are made of different materials.

7. The method for preparing the mask structure according to claim 6, characterized in that, The first mask layer includes a first sub-mask layer and a first stop layer, and the second mask layer includes a second sub-mask layer and a second stop layer; the first sub-mask layer and the second sub-mask layer have the same thickness.

8. The method for preparing the mask structure according to claim 7, characterized in that, The step of etching the first mask layer using the second initial trench to form a plurality of second patterns in the first mask layer in the first region includes: The second stop layer and the first stop layer exposed in the first region, as well as the second stop layer in the second region, are etched. The second sub-mask layer, the first backfill layer, and the second sub-mask layer exposed in the first region, as well as the second sub-mask layer in the second region, are etched to form a plurality of second patterns in the first mask layer in the first region; the second trench exposes the pattern transfer layer.

9. The method for preparing the mask structure according to claim 1, characterized in that, The first sacrificial layer, the second sacrificial layer, and the pattern transfer layer are made of the same material.

10. The method for preparing the mask structure according to claim 6, characterized in that, The formation of the second backfill layer includes: A second backfill layer is formed in the first region and the second region, the second backfill layer fills the second trench and covers the second sacrificial layer in the first region and the second region; the top of the second backfill layer in the first region is lower than the top of the second backfill layer in the second region.

11. The method for preparing the mask structure according to claim 10, characterized in that, The second backfill layer is made of the same material as the first mask layer, and the first mask layer is made of a different material than the second sacrificial layer.

12. The method for preparing the mask structure according to claim 1, characterized in that, The removal of the second backfill layer located on the top surface of the second graphic includes: The second backfill layer on the top surface of the second pattern and the second backfill layer in the second region are removed using a planarization process to make the first region and the second region flush; or The second sacrificial layer and the second backfill layer on the top surface of the second pattern, as well as the second sacrificial layer and the second backfill layer in the second region, are removed using a planarization process to make the first region and the second region flush.

13. The method for preparing the mask structure according to claim 1, characterized in that, The substrate includes a third stop layer, and the pattern transfer layer is located on the third stop layer; the etching downward along the second sacrificial layer located on the sidewall of the second pattern to form a plurality of third patterns in the pattern transfer layer on the first region includes: Remove the second sacrificial layer from the second pattern sidewall to form a third initial trench that exposes the pattern transfer layer; The pattern transfer layer is etched using the third initial trench to form a plurality of third patterns in the pattern transfer layer on the first region; a third trench is provided between adjacent third patterns, and the third trench exposes the third stop layer.

14. The method for preparing the mask structure according to claim 1, characterized in that, The density of the plurality of second patterns is twice the density of the plurality of first patterns; the density of the plurality of third patterns is twice the density of the plurality of second patterns.

15. A method for fabricating a semiconductor device, characterized in that, The method includes: A semiconductor substrate is provided, the surface of which has a layer to be etched; The plurality of third patterns are formed on the layer to be etched using the mask structure fabrication method as described in any one of claims 1-14; The layer to be etched is etched based on the plurality of third patterns to transfer the patterns of the plurality of third patterns into the layer to be etched.

16. The method for fabricating a semiconductor device according to claim 15, characterized in that, The layer to be etched includes a metal layer.

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