A method of manufacturing a semiconductor structure and a material removal method

Abstract

The application provides a semiconductor structure preparation method and a material removal method. The semiconductor structure preparation method comprises the following steps: providing a semiconductor substrate comprising a first region and a second region; forming a plurality of trenches in the first region; forming a first film layer on the sidewalls and bottom walls of the trenches and the semiconductor substrate surfaces of the first region and the second region; filling a conductive material in the trenches with the first film layer on the sidewalls and bottom walls; removing part of the conductive material in the trenches to form a groove above the trenches; forming a second film layer on the semiconductor substrate surfaces with the groove to reduce the width of the groove or fill the groove; wherein the difference between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference under the same conditions; and removing part of the first film layer and the second film layer. The scheme provided by the application can accurately remove excess material without damaging other film layers.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, specifically to a method for preparing a semiconductor structure and a method for removing materials. Background Technology

[0002] In the field of semiconductor technology, when fabricating trench power devices, trenches are first formed in a substrate, and then filled with material. During material filling, excess material is often deposited in the areas outside the trenches, thus requiring removal. However, in related technologies, removing excess material often damages other film layers. Therefore, how to accurately remove excess material without damaging other film layers has become a pressing technical problem. Summary of the Invention

[0003] This application provides a method for fabricating a semiconductor structure and a method for removing materials, which can accurately remove excess material without damaging other film layers. The specific solution is as follows: In a first aspect, embodiments of this application provide a method for fabricating a semiconductor structure, the method comprising: A semiconductor substrate is provided; the semiconductor substrate includes a first region and a second region; Multiple trenches are formed in a first region of the semiconductor substrate; The first film layer is formed on the sidewalls and bottom wall of the trench, as well as on the semiconductor substrate surface of the first region and the semiconductor substrate surface of the second region; The trenches on which the first film layer is formed are filled with conductive material; Remove a portion of the conductive material from the trench to form a groove above the trench; A second film layer is formed on the surface of the semiconductor substrate in which the groove is formed, so as to reduce the width of the groove or fill the groove; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference. Remove portions of the first and second membrane layers.

[0004] Optionally, forming a plurality of trenches in the first region of the semiconductor substrate includes: A first oxide layer is formed on the surface of the semiconductor; A nitrided layer is formed on the surface of the first oxide layer; An etching step is performed to form a plurality of trenches in a first region of the semiconductor substrate on which the first oxide layer and the nitride layer are formed.

[0005] Optionally, removing portions of the first and second film layers includes: Using the nitrided layer as a stop layer, a portion of the first film layer and the second film layer are removed.

[0006] Optionally, the first film layer and the second film layer are made of the same material.

[0007] Optionally, the first film layer and the second film layer are oxide layers.

[0008] Secondly, embodiments of this application provide a material removal method, the method comprising: A semiconductor substrate is provided; a first film layer is formed on the surface of the semiconductor substrate, the semiconductor substrate includes a first region and a second region, and the difference in the continuity between the surface unevenness of the first region and the surface unevenness of the second region is greater than a preset continuity difference. A second film layer is formed on the surface of the first region and the surface of the second region, such that the difference in the degree of continuity between the surface unevenness of the first region and the surface unevenness of the second region is less than or equal to the preset degree of continuity difference; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than the preset removal rate difference. Remove portions of the first and second membrane layers.

[0009] Optionally, a plurality of grooves are formed in the first film layer on the surface of the first region, and the surface of the first film layer on the surface of the second region is flat and without grooves.

[0010] Optionally, forming a second film layer on the surfaces of the first region and the second region, such that the difference in the degree of continuity between the surface roughness of the first region and the surface roughness of the second region is less than or equal to the preset degree of continuity difference, includes: A second film layer is formed on the surface of the semiconductor substrate in which the groove is formed, so as to reduce the width of the groove or fill the groove.

[0011] Optionally, the provision of the semiconductor substrate includes: Provide semiconductor substrates; Multiple trenches are formed in a first region of the semiconductor substrate; The first film layer is formed on the sidewalls and bottom wall of the trench, as well as on the semiconductor substrate surface of the first region and the semiconductor substrate surface of the second region; The trenches on which the first film layer is formed are filled with conductive material; Remove some of the conductive material from the trench to form a groove above the trench.

[0012] Optionally, the first film layer and the second film layer are made of the same material.

[0013] Optionally, the first film layer and the second film layer are oxide layers.

[0014] Compared with the prior art, this application has the following advantages: The semiconductor structure fabrication method provided in the first embodiment of this application includes the following steps: providing a semiconductor substrate; the semiconductor substrate includes a first region and a second region; forming a plurality of trenches in the first region of the semiconductor substrate; forming a first film layer on the sidewalls and bottom walls of the trenches, as well as on the semiconductor substrate surfaces of the first region and the second region; filling the trenches on the sidewalls and bottom walls with the first film layer with conductive material; removing a portion of the conductive material in the trenches to form a groove above the trenches; forming a second film layer on the semiconductor substrate surface with the groove to reduce the width of the groove or to fill the groove; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference; and removing a portion of the first film layer and the second film layer.

[0015] As can be seen, the semiconductor structure fabrication method provided in the first embodiment of this application, after forming multiple trenches in the first region, first forms a groove above the trenches. This avoids excessive removal of silicon nitride caused by inconsistent removal rates when the first film layer and conductive material are removed together as excess material. Subsequently, a second film layer with a smaller difference between its removal rate and the removal rate of the first film layer is formed on the sidewalls and bottom walls of the grooves in the first region and the first film layer. Furthermore, the width of the grooves filling the second film layer narrows or disappears. Thus, the interface uniformity of the first region and the second region is similar, and the removal rates of excess material in the first region and the second region are similar under the same conditions. Therefore, after removing part of the first and second film layers, the surfaces of the first and second regions will not be uneven. This not only ensures a good interface morphology but also avoids the risks of nitride layer wear-through and device leakage failure caused by excessive nitride layer removal. Therefore, the semiconductor structure fabrication method provided in the first embodiment of this application can accurately remove excess material without damaging other film layers.

[0016] The material removal method provided in the second embodiment of this application includes the following steps: providing a semiconductor substrate; forming a first film layer on the surface of the semiconductor substrate, the semiconductor substrate including a first region and a second region, wherein the difference in the continuity between the surface roughness of the first region and the surface roughness of the second region is greater than a preset continuity difference; forming a second film layer on the surface of the first region and the surface of the second region, such that the difference in the continuity between the surface roughness of the first region and the surface roughness of the second region is less than or equal to the preset continuity difference; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than the preset removal rate difference; and removing a portion of the first film layer and the second film layer.

[0017] In existing technologies, when performing a polishing process on a substrate, the substrate surface typically has an uneven pattern, making it difficult to accurately remove excess material without damaging the underlying structure, resulting in poor material removal performance. In contrast, the material removal method provided in the second embodiment of this application, after forming a second film layer on the surfaces of the first and second regions, can minimize the difference in the surface unevenness continuity between the first and second regions, thus reducing the difference in interface uniformity between the first and second regions. Furthermore, under the same conditions, the smaller difference in removal rate between the first and second film layers ensures that the removal rates of excess material in the first and second regions are similar under the same conditions. Therefore, after removing part of the first and second film layers, the surfaces of the first and second regions will not exhibit unevenness, ensuring a good interface morphology and avoiding the risk of device leakage failure due to excessive removal of other film layers. Therefore, the material removal method provided in the second embodiment of this application can accurately remove excess material without damaging other film layers, thereby improving material removal performance. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for preparing the semiconductor structure provided in the first embodiment of this application.

[0019] Figure 2 This is a schematic diagram of the semiconductor substrate provided in the semiconductor structure fabrication method provided in the first embodiment of this application.

[0020] Figure 3 This is a schematic diagram of the formation of a nitride layer in the semiconductor structure fabrication method provided in the first embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the trench formation process in the semiconductor structure fabrication method provided in the first embodiment of this application.

[0022] Figure 5 This is a schematic diagram of the formation of the first film layer in the semiconductor structure preparation method provided in the first embodiment of this application.

[0023] Figure 6 This is a schematic diagram of filling the trench with conductive material in the method for preparing the semiconductor structure provided in the first embodiment of this application.

[0024] Figure 7 This is a schematic diagram of removing part of the conductive material in the trench during the preparation method of the semiconductor structure provided in the first embodiment of this application.

[0025] Figure 8 This is a schematic diagram of the formation of the second film layer in the semiconductor structure preparation method provided in the first embodiment of this application.

[0026] Figure 9 This is a schematic diagram illustrating the process of removing excess material in the preparation method of the semiconductor structure provided in the first embodiment of this application.

[0027] Figure 10 This is a schematic diagram of another material removal method.

[0028] Figure 11 This is a flowchart of the material removal method provided in the second embodiment of this application. Detailed Implementation

[0029] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0030] It should be noted that the terms "first," "second," "third," etc., in the claims, specification, and drawings of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. Such data are interchangeable where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than that shown or described herein. Furthermore, the terms "comprising," "having," and their variations are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0031] It should be understood that in the embodiments of this application, "at least one" means one or more, and "more than one" means two or more. "And / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. The character " / " generally indicates that the related objects before and after it are in an "or" relationship. "Contains A, B and / or C" means containing any one, two, or three of A, B, and C.

[0032] It should be understood that in the embodiments of this application, "B corresponding to A", "B corresponding to A", "A corresponds to B" or "B corresponds to A" means that B is associated with A, and B can be determined based on A. Determining B based on A does not mean that B is determined solely based on A; B can also be determined based on A and / or other information.

[0033] Based on the reasons mentioned in the background art, the first embodiment of this application provides a method for preparing a semiconductor structure, and the second embodiment of this application provides a material removal method that can accurately remove excess material without damaging other film layers.

[0034] like Figure 1 The diagram shown is a flowchart of a method for fabricating a semiconductor structure according to the first embodiment of this application, including the following steps S101 to S107.

[0035] Step S101: Provide a semiconductor substrate; the semiconductor substrate includes a first region and a second region.

[0036] The semiconductor substrate refers to the substrate material used to fabricate various semiconductor structures and integrated circuits. It is the foundational substrate at the bottom of chip manufacturing and the carrier for epitaxial layers and thin-film circuit structures. The semiconductor substrate can be made of any one of pure single-crystal silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), etc. The semiconductor substrate can be a P-type semiconductor substrate or an N-type semiconductor substrate; this application does not impose specific limitations on this.

[0037] Step S102: Form a plurality of trenches in the first region of the semiconductor substrate.

[0038] In this embodiment, the semiconductor structure prepared can be a trench structure, such as an SGT (Shielded Gate Transistor) or a trench MOS (Trench Metal-Oxide-Semiconductor Field-Effect Transistor). The multiple trenches (2, 3, 4, etc.) formed in the first region in this step correspond to the trench structure to be formed. This application does not impose a specific limit on the number of trenches; it can be set according to the actual situation.

[0039] The following combination Figures 2-3 The method for fabricating a semiconductor structure according to the first embodiment of this application, which involves forming multiple trenches in the first region, will be described in detail below: like Figure 2 The diagram shown is a schematic of the semiconductor substrate provided in the semiconductor structure fabrication method according to the first embodiment of this application. First, a semiconductor substrate 101 is provided. Then, a first oxide layer 102 can be formed on the surface of the semiconductor substrate 101. The material of the first oxide layer 102 can be silicon oxide. Specifically, the first oxide layer 102 can be formed on the surface of the semiconductor substrate 101 by thermal oxidation or vapor deposition.

[0040] In some examples, the semiconductor substrate may include a substrate layer and an epitaxial layer. The substrate is the bottom layer of the entire wafer, serving as a single-crystal base for mechanical support and forming the substrate base of the entire chip. It is fabricated through single-crystal pulling, slicing, and polishing, without needing to be grown on another substrate. The epitaxial layer refers to a new material layer with a specific doping concentration and crystal structure grown on the original semiconductor substrate through epitaxy (EPI). During the formation of the epitaxial layer, the composition, thickness, doping type, and concentration of the new material layer can be controlled to achieve specific electrical properties. The epitaxial layer can be matched to the substrate at the atomic level to form a continuous crystal structure. In this example, specifically, the first oxide layer 102 can be formed on the surface of the epitaxial layer.

[0041] like Figure 3 As shown, after forming a first oxide layer 102 on the surface of the semiconductor substrate 101, a nitride layer 103 can be formed on the surface of the first oxide layer 102. The nitride layer 103 can be made of silicon nitride, and specifically, it can be formed on the surface of the first oxide layer 102 by chemical vapor deposition. This nitride layer 103 can serve as a stop layer for subsequent removal of excess material.

[0042] like Figure 4As shown, the semiconductor substrate 101 may include a first region 20 and a second region 21, where the first region is the region where trenches are to be formed. After a nitride layer 103 is formed on the surface of the first oxide layer 102, a plurality of trenches may be formed in the first region 20 of the semiconductor substrate 101 on which the first oxide layer 102 and the nitride layer 103 are formed.

[0043] In practice, the formation locations of multiple trenches to be formed can be defined in the first region 20 using photolithography. Then, an etching step is performed to form multiple trenches 104 at those locations. No trench structure is formed on the surface of the second region 21 of the semiconductor substrate.

[0044] Step S103: The first film layer is formed on the sidewalls and bottomwalls of the trench, as well as on the semiconductor substrate surfaces of the first region and the second region.

[0045] like Figure 5 The diagram shown is a schematic representation of the formation of a first film layer in the semiconductor structure fabrication method provided in the first embodiment of this application. After forming a plurality of trenches 104 in the first region, a first film layer 105 can be formed on the sidewalls and bottom walls of the trenches 104, as well as on the surface of the semiconductor substrate in the first region 20 where the nitride layer 103 is formed and on the surface of the semiconductor substrate in the second region 21. The first film layer 105 is an insulating layer, such as an oxide layer.

[0046] Step S104: Fill the trenches on the sidewalls and bottomwalls where the first film layer is formed with conductive material.

[0047] like Figure 6 The diagram shown illustrates the filling of a conductive material into a trench in the semiconductor structure fabrication method provided in the first embodiment of this application. After forming a first film layer 105 on the sidewalls and bottom wall of the trench 104, and on the surface of the semiconductor substrate in the first region 20 and the second region 21 where the nitride layer 103 is formed, a conductive material 106 can be filled into the trench 104 where the first film layer 105 is formed on the sidewalls and bottom wall. The conductive material 106 can be polycrystalline silicon or a metal, and this application does not limit it.

[0048] Specifically, excess conductive material may be formed on the surface of the first film layer 105. In this embodiment, the excess conductive material formed on the surface of the first film layer 105 can be removed.

[0049] Step S105: Remove a portion of the conductive material from the trench to form a groove above the trench.

[0050] like Figure 7The diagram shown illustrates the removal of a portion of the conductive material in a trench during the fabrication of a semiconductor structure according to the first embodiment of this application. An etching step can be performed to remove a portion of the conductive material 106 filling the trench 104. The height difference between the surface of the remaining conductive material 106 and the surface of the nitride layer 103 can be less than a preset height difference value; for example, the surface of the remaining conductive material 106 can be flush with the surface of the nitride layer 103. In this way, a groove 107 can be formed above the trench 104.

[0051] In this embodiment, by first removing a portion of the conductive material 106 in the trench 104, excessive removal of the nitride layer 103 can be avoided when removing excess material later. In the prior art, when the trench 104 is simultaneously filled with a first film layer and conductive material, the conductive material is usually not pre-removed. In this case, the excess material includes excess first film layer and excess conductive material. When removing (e.g., grinding) excess material using the nitride layer 103 as a stop layer, the removal rates of the first film layer and the conductive material are significantly different. As a result, the amount of material removed by grinding in the area where the first film layer is located and the area where the conductive material is located differs significantly under the same removal conditions, and the process controllable window is narrow. This leads to continuous grinding in the area where the nitride layer is first exposed, resulting in a large loss of the nitride layer film and a large difference in the remaining nitride layer thickness. This not only causes the film thickness to become uncontrollable but also poses risks such as wear through the nitride layer in some areas and device leakage failure. In contrast, in this embodiment, the conductive material filling the trench is removed beforehand to form a groove, and a second film layer is formed in the groove in a subsequent step. The second film layer is a film layer in which the difference between the removal rate and the removal rate of the second film layer under the same conditions is less than a preset removal rate difference. In this way, the excessive removal of the nitride layer caused by the grinding difference between the conductive material and the first film layer can be avoided.

[0052] Step S106: A second film layer is formed on the surface of the semiconductor substrate on which the groove is formed, so as to reduce the width of the groove or fill the groove; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference.

[0053] like Figure 8The diagram illustrates the formation of a second film layer in the semiconductor structure fabrication method provided in the first embodiment of this application. After forming the groove 107, a second film layer 108 can be formed on the surface of the semiconductor substrate where the groove 107 is formed. That is, the second film layer 108 is formed on the surface of the first film layer 105 and on the sidewalls and bottom walls of the groove 107 in the first region 20. Furthermore, the width of the groove 107 decreases or the groove 107 is completely filled after the second film layer 108 is filled (the diagram illustrates this by showing a decrease in the width of the groove 107). In other words, the groove 107 becomes narrower or disappears after the second film layer 108 is filled. This makes the continuity of the surface of the first region more similar to that of the surface of the second region, and the difference in interface uniformity between the first and second regions is smaller.

[0054] Under the same conditions (such as grinding conditions), the difference in removal rate between the first film layer 105 and the second film layer 108 is less than a preset removal rate difference. In other words, under the same conditions, the difference in removal rate between the first film layer 105 and the second film layer 108 is small. For example, if the first film layer 105 and the second film layer 108 are made of the same material, both being oxide layers, then the removal rate of the first film layer 105 and the second film layer 108 are the same.

[0055] After the grooves 107 are formed, the first film layer 105 on the surface of the first region 20 includes multiple grooves 107, while the surface of the second region 21 is a uniform, continuous, and flat first film layer 105. If the nitride layer 103 is used as a stop layer to remove part of the first film layer 105, the removal rate of the first film layer in the first region 20 will be greater than that in the second region 21. This will result in the nitride layer 103 being exposed in the first region 20, while it will not be exposed in the second region 21. This will lead to the over-removal of the nitride layer 103 in the first region 20, resulting in poor interface morphology and the risk of nitride layer wear-through and device leakage failure in the first region 20.

[0056] In contrast, in this embodiment, after forming the groove 107, a second film layer 108 is formed on the surface of the first film layer 105 and on the sidewalls and bottomwalls of the groove 107 in the first region 20. Since the difference between the removal rate of the first film layer 105 and the removal rate of the second film layer 108 is small under the same conditions, and the width of the groove 107 becomes narrower or disappears after filling the second film layer 108, the interface uniformity of the first region 20 and the second region 21 is small when the first film layer 105 is partially removed with the nitriding layer 103 as a stop layer. Furthermore, under the same removal conditions, the difference in removal rate between the material to be removed in the first region 20 above the nitriding layer 103 and the material to be removed in the second region 21 is small. In this way, the first region 20 and the second region 21 can maintain a relatively consistent removal rate. This allows for the removal of excess material above the nitride layer 103 in the first region 20 while also removing excess material above the nitride layer 103 in the second region 21. This prevents the nitride layer 103 in the first region 20 from being over-removed, thus ensuring the interface morphology and avoiding risks such as nitride layer wear-through and device leakage failure.

[0057] Step S107: Remove a portion of the first film layer and the second film layer.

[0058] like Figure 9 The diagram shown is a schematic representation of the process for removing excess material in the semiconductor structure fabrication method provided in the first embodiment of this application. The excess material is the material above the nitride layer 103. After forming the second film layer 108, the nitride layer 103 can be used as a stop layer to perform a removal process (such as grinding (CMP, Chemical Mechanical Polishing) or etching; this application uses grinding as an example) to remove a portion of the first film layer 105 and the second film layer 108. Since the interface uniformity of the first region 20 and the second region 21 is relatively similar, and the removal rate difference between the first film layer 105 and the second film layer 108 is small, when using the nitride layer 103 as a stop layer to remove a portion of the first film layer 105 and the second film layer 108, the first region 20 and the second region 21 will maintain a relatively consistent removal rate, forming a well-formed interface. This also avoids the risks of nitride layer wear-through and device leakage failure caused by excessive nitride layer removal.

[0059] When the first and second film layers are oxide layers, there is a stable and significantly different grinding selectivity between the oxide layer and the nitrided layer. The grinding fluid removes oxide layers much faster than nitrided layers. When grinding reaches the surface of the nitrided layer, the removal rate drops sharply. The equipment can quickly detect the rate change signal and stop in time, effectively protecting the nitrided layer and reducing the risk of over-grinding.

[0060] The semiconductor structure fabrication method provided in the first embodiment of this application includes the following steps: providing a semiconductor substrate; the semiconductor substrate includes a first region and a second region; forming a plurality of trenches in the first region of the semiconductor substrate; forming a first film layer on the sidewalls and bottom walls of the trenches, as well as on the semiconductor substrate surfaces of the first region and the second region; filling the trenches on the sidewalls and bottom walls with the first film layer with conductive material; removing a portion of the conductive material in the trenches to form a groove above the trenches; forming a second film layer on the semiconductor substrate surface with the groove to reduce the width of the groove or to fill the groove; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference; and removing a portion of the first film layer and the second film layer.

[0061] As can be seen, the semiconductor structure fabrication method provided in the first embodiment of this application, after forming multiple trenches in the first region, first forms a groove above the trenches. This avoids excessive removal of silicon nitride caused by inconsistent removal rates when the first film layer and conductive material are removed together as excess material. Subsequently, a second film layer with a smaller difference between its removal rate and the removal rate of the first film layer is formed on the sidewalls and bottom walls of the grooves in the first region and the first film layer. Furthermore, the width of the grooves filling the second film layer narrows or disappears. Thus, the interface uniformity of the first region and the second region is similar, and the removal rates of excess material in the first region and the second region are similar under the same conditions. Therefore, after removing part of the first and second film layers, the surfaces of the first and second regions will not be uneven. This not only ensures a good interface morphology but also avoids the risks of nitride layer wear-through and device leakage failure caused by excessive nitride layer removal. Therefore, the semiconductor structure fabrication method provided in the first embodiment of this application can accurately remove excess material without damaging other film layers.

[0062] Furthermore, to avoid excessive differences in removal rates between the first region 20 and the second region 21, some technologies also provide, for example... Figure 10The method is illustrated. After forming a groove 107 above the trench in the first region 20, photoresist 22 can be applied to the second region first. Then, the position to be formed in the second region is defined on the photoresist 22. After that, an etching step is performed to form a groove 23 at that position. This method forms a groove in the second region so that the difference in the continuity between the surface roughness of the first region and the surface roughness of the second region is less than or equal to a preset continuity difference. That is, the interface uniformity of the first region and the interface uniformity of the second region are relatively similar. In this way, it can be ensured that the removal rate of the first film layer 105 in the first region is relatively consistent with the removal rate of the first film layer 105 in the second region, thereby avoiding the over-removal of the nitride layer 103 due to an excessive difference in the removal rate between the first region and the second region. However, compared with the method of forming a second film layer to avoid an excessive difference in the removal rate between the first region and the second region, Figure 10 The method shown requires an additional mask to etch the groove 23 in the second region. In this embodiment, by forming a second film layer, it is possible to save process steps while avoiding excessive differences in removal rates between the first and second regions. The above is a description of the semiconductor structure fabrication method provided in the first embodiment of this application.

[0063] like Figure 11 The diagram shown is a flowchart of the material removal method provided in the second embodiment of this application, including steps S201 to S203: Step S201: Provide a semiconductor substrate; a first film layer is formed on the surface of the semiconductor substrate, the semiconductor substrate includes a first region and a second region, and the difference in the continuity between the surface unevenness of the first region and the surface unevenness of the second region is greater than a preset continuity difference.

[0064] In this embodiment, a first film layer, which may be an oxide layer, is formed on the surface of the semiconductor substrate. The difference in the continuity between the surface roughness of the first region and the surface roughness of the second region in the semiconductor substrate is greater than a preset continuity difference. That is, the difference between the surface roughness continuity of the first region and the second region is large, with the first region being sparser and the second region being denser. Therefore, when removing excess material, the removal rate of excess material above the first region will be greater than the removal rate of excess material above the second region.

[0065] Optionally, a plurality of grooves are formed in the first film layer on the surface of the first region, and the surface of the first film layer on the surface of the second region is flat and without grooves.

[0066] In a specific example, the semiconductor substrate in the material removal method provided in the second embodiment of this application can be formed through steps S101 to S105 of the semiconductor structure fabrication method provided in the first embodiment of this application. Specifically, a first oxide layer can be formed on the surface of the semiconductor substrate first; then, a nitride layer can be formed on the surface of the first oxide layer; subsequently, an etching step is performed to form multiple trenches in a first region of the semiconductor substrate on which the first oxide layer and the nitride layer are formed; then, a first film layer is formed on the sidewalls and bottom walls of the trenches, as well as on the semiconductor substrate surfaces of the first and second regions; conductive material is filled in the trenches on which the first film layer is formed; and a portion of the conductive material in the trenches is removed to form a groove above the trenches, thereby obtaining the semiconductor substrate in the material removal method provided in the second embodiment of this application. For details, please refer to the relevant descriptions of steps S101 to S105 of the semiconductor structure fabrication method provided in the first embodiment of this application, which will not be repeated here.

[0067] Step S202: A second film layer is formed on the surface of the first region and the surface of the second region, such that the difference in the degree of continuity between the surface unevenness of the first region and the surface unevenness of the second region is less than or equal to the preset degree of continuity difference; under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than the preset removal rate difference.

[0068] In this embodiment, after forming a second film layer on the surfaces of the first and second regions, the difference in the continuity between the surface roughness of the first and second regions is less than or equal to the preset continuity difference. In other words, the difference between the surface roughness of the first and second regions is small. This results in a smaller difference in the interface uniformity between the first and second regions. Furthermore, under the same conditions, the smaller difference in removal rates between the first and second film layers ensures that the removal rates of excess material in the first and second regions are similar under the same conditions.

[0069] For details of this step, please refer to the relevant description of step S106 in the semiconductor structure preparation method provided in the first embodiment of this application, which will not be repeated here.

[0070] Step S203: Remove a portion of the first film layer and the second film layer.

[0071] This step can be referred to the relevant description of step S107 in the semiconductor structure preparation method provided in the first embodiment of this application, and will not be repeated here.

[0072] Since the interface uniformity of the first region and the interface uniformity of the second region are similar, and the removal rates of excess material in the first region and the second region are similar under the same conditions, after removing part of the first and second film layers, the surfaces of the first and second regions will not be uneven. This not only ensures a good interface morphology, but also avoids the risk of device leakage failure caused by excessive removal of other film layers.

[0073] The material removal method provided in the second embodiment of this application includes the following steps: providing a semiconductor substrate; forming a first film layer on the surface of the semiconductor substrate, the semiconductor substrate including a first region and a second region, wherein the difference in the continuity between the surface roughness of the first region and the surface roughness of the second region is greater than a preset continuity difference; forming a second film layer on the surface of the first region and the surface of the second region, such that the difference in the continuity between the surface roughness of the first region and the surface roughness of the second region is less than or equal to the preset continuity difference; under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than the preset removal rate difference; and removing a portion of the first film layer and the second film layer.

[0074] In existing technologies, when performing a polishing process on a substrate, the substrate surface typically has an uneven pattern, making it difficult to accurately remove excess material without damaging the underlying structure, resulting in poor material removal performance. In contrast, the material removal method provided in the second embodiment of this application, after forming a second film layer on the surfaces of the first and second regions, can minimize the difference in the surface unevenness continuity between the first and second regions, thus reducing the difference in interface uniformity between the first and second regions. Furthermore, under the same conditions, the smaller difference in removal rate between the first and second film layers ensures that the removal rates of excess material in the first and second regions are similar under the same conditions. Therefore, after removing part of the first and second film layers, the surfaces of the first and second regions will not exhibit unevenness, ensuring a good interface morphology and avoiding the risk of device leakage failure due to excessive removal of other film layers. Therefore, the material removal method provided in the second embodiment of this application can accurately remove excess material without damaging other film layers, thereby improving material removal performance.

[0075] The above is a description of the material removal method provided in the second embodiment of this application.

[0076] Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A method for fabricating a semiconductor structure, characterized in that, The method includes: A semiconductor substrate is provided; the semiconductor substrate includes a first region and a second region; Multiple trenches are formed in a first region of the semiconductor substrate; The first film layer is formed on the sidewalls and bottom wall of the trench, as well as on the semiconductor substrate surface of the first region and the semiconductor substrate surface of the second region; The trenches on which the first film layer is formed are filled with conductive material; Remove a portion of the conductive material from the trench to form a groove above the trench; A second film layer is formed on the surface of the semiconductor substrate in which the groove is formed, so as to reduce the width of the groove or fill the groove; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than a preset removal rate difference. Remove portions of the first and second membrane layers.

2. The method according to claim 1, characterized in that, The formation of multiple trenches in the first region of the semiconductor substrate includes: A first oxide layer is formed on the surface of the semiconductor; A nitrided layer is formed on the surface of the first oxide layer; An etching step is performed to form a plurality of trenches in a first region of the semiconductor substrate on which the first oxide layer and the nitride layer are formed.

3. The method according to claim 2, characterized in that, The removal of portions of the first and second membrane layers includes: Using the nitrided layer as a stop layer, a portion of the first film layer and the second film layer are removed.

4. A method for removing material, characterized in that, The method includes: A semiconductor substrate is provided; a first film layer is formed on the surface of the semiconductor substrate, the semiconductor substrate includes a first region and a second region, and the difference in the continuity between the surface unevenness of the first region and the surface unevenness of the second region is greater than a preset continuity difference. A second film layer is formed on the surface of the first region and the surface of the second region, such that the difference in the degree of continuity between the surface unevenness of the first region and the surface unevenness of the second region is less than or equal to the preset degree of continuity difference; wherein, under the same conditions, the difference in removal rate between the removal rate of the first film layer and the removal rate of the second film layer is less than the preset removal rate difference. Remove portions of the first and second membrane layers.

5. The method according to claim 4, characterized in that, The first film layer on the surface of the first region has multiple grooves, while the surface of the first film layer on the surface of the second region is flat and without grooves.

6. The method according to claim 5, characterized in that, The step of forming a second film layer on the surfaces of the first region and the second region, such that the difference in the degree of continuity between the surface roughness of the first region and the surface roughness of the second region is less than or equal to the preset degree of continuity difference, includes: A second film layer is formed on the surface of the semiconductor substrate in which the groove is formed, so as to reduce the width of the groove or fill the groove.

7. The method according to claim 4, characterized in that, The provision of the semiconductor substrate includes: Provide semiconductor substrates; Multiple trenches are formed in a first region of the semiconductor substrate; The first film layer is formed on the sidewalls and bottom wall of the trench, as well as on the semiconductor substrate surface of the first region and the semiconductor substrate surface of the second region; The trenches on which the first film layer is formed are filled with conductive material; Remove some of the conductive material from the trench to form a groove above the trench.

8. The method according to any one of claims 1 to 7, characterized in that, The first film layer and the second film layer are made of the same material.

9. The method according to any one of claims 1 to 8, characterized in that, The first film layer and the second film layer are oxide layers.

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