Feature filling method and semiconductor structure

Abstract

The present application provides a feature filling method and a semiconductor structure. The feature filling method includes providing a substrate including a plurality of features, each feature having a feature opening, a feature sidewall, and a feature bottom respectively; the feature filling method of the present application can timely or real-time obtain the topography of the first deposition layer at the feature opening, determine whether a convex portion is formed, and when a convex portion is formed at the feature opening, use an etching medium to etch the first deposition layer, so that the first deposition layer at the feature opening is etched prior to the first deposition layer at the feature sidewall and the feature bottom; according to the feature filling method of the present application, the convex portion can be modified prior to etching to further achieve selective etching of the convex portion, thereby effectively reducing or removing the convex portion, preventing the convex portion from closing the feature opening, avoiding the formation of holes inside the feature, and improving the feature filling rate while enhancing the chip performance.

Description

Field of Technology

[0001] This application mainly relates to the field of semiconductors, and particularly relates to a feature filling method and a semiconductor structure. Background Art

[0002] Gas-phase processes, such as Chemical Vapor Deposition (CVD), Plasma Enhanced Chemical Vapor Deposition (PECVD), Atomic Layer Deposition (ALD), etc., are often used for the deposition of materials on the surface of a substrate. For example, using gas-phase processes, layers can be deposited on a substrate, and then semiconductor devices, flat display devices, photovoltaic devices, and Micro-Electro-Mechanical Systems (MEMS) can be manufactured.

[0003] As the minimum feature size of semiconductor devices continues to shrink, the size of memory cells also decreases. In Dynamic Random Access Memory (DRAM), the required unit capacitance has been achieved by means of three-dimensional cells with a high aspect ratio. Especially in the near future, semiconductor memories will adopt an aspect ratio exceeding 100. Therefore, good conformality has become one of the key requirements for manufacturing microelectronic devices.

[0004] Atomic Layer Deposition (ALD) is a very promising technology suitable for growing thin films with uniform thickness on microscopic features with a large aspect ratio. The core feature of ALD lies in the surface-limited reaction that occurs when precursor gases and reaction gases are dosed alternately. In this case, the film growth has self-limiting properties, which can not only ensure simple and precise control of the film thickness but also guarantee excellent film step coverage. In addition, due to the alternate metering of precursor gases and reaction gases, harmful gas-phase reactions are essentially eliminated. However, even with the ALD technology, it is not easy to obtain a conformal film thickness on microscopic features when the aspect ratio increases sharply. Therefore, an improved feature filling method is needed to ensure the step coverage characteristics in various small features, improve the film filling rate in holes, trenches, and other 3D structures as much as possible, and reduce problems such as pores and seams. Summary of the Invention

[0005] This application addresses the above technical problems and provides a feature filling method and a semiconductor structure, which can effectively remove the protrusions at the feature openings, prevent the features from being blocked by the protrusions, avoid forming holes inside the features, and improve the filling rate and chip performance.

[0006] To solve the above technical problems, the present application provides a feature filling method, including: providing a substrate including a plurality of features, the plurality of features being spaced apart on the substrate, each feature having a feature opening, a feature sidewall, and a feature bottom; filling the plurality of features by an ALD process to conformally form a first deposition layer in the plurality of features, the first deposition layer covering the feature opening, the feature sidewall, and the feature bottom; obtaining the topography of the first deposition layer at the feature opening, and determining whether a convex portion is formed at the feature opening of the first deposition layer, wherein the convex portion protrudes toward the center of the feature opening; in response to the formation of the convex portion at the feature opening, etching the first deposition layer with an etching medium so that the first deposition layer at the feature opening is etched prior to the first deposition layer at the feature sidewall and the feature bottom; and determining whether the etching result of the first deposition layer reaches a predetermined etching target, and in response to the etching result reaching the predetermined etching target, stopping etching the first deposition layer and filling the plurality of features again by the ALD process to conformally form a second deposition layer in the plurality of features.

[0007] In an embodiment of the present application, before etching the first deposition layer with the etching medium, it further includes: modifying at least part of the first deposition layer with a modifying medium, wherein at least part of the first deposition layer includes the first deposition layer at the feature opening; and determining whether the modification result of at least part of the first deposition layer reaches a predetermined modification target, and in response to the modification result reaching the predetermined modification target, stopping the modification process.

[0008] In an embodiment of the present application, determining whether the modification result of at least part of the first deposition layer reaches a predetermined modification target includes: before the modification process, measuring a first height of the convex portion in the depth direction of the feature; after the modification process, measuring a second height of at least part of the first deposition layer in the depth direction of the feature; calculating a height ratio, the height ratio being the ratio of the first height to the second height; and if the height ratio reaches a predetermined height ratio range, determining that the modification result of at least part of the first deposition layer reaches the predetermined modification target.

[0009] In an embodiment of the present application, the predetermined height ratio range includes: 1±δ, 0<δ≤0.5.

[0010] In an embodiment of the present application, measuring the first height of the convex portion in the depth direction of the feature includes: measuring the thicknesses of the first deposition layer at the feature opening and on the feature sidewall, where the thicknesses vary along the depth direction of the feature; determining a first position starting from the feature opening and along the depth direction of the feature towards the feature bottom, where the first position is the position where the thickness of the first deposition layer decreases to the theoretical deposition thickness of the first deposition layer; and taking the distance between the first position and the first upper surface of the first deposition layer as the first height; measuring the second height of at least part of the first deposition layer in the depth direction of the feature includes: determining a second position of at least part of the first deposition layer closest to the feature bottom after the modification treatment along the depth direction of the feature, and taking the distance between the second position and the second upper surface of the first deposition layer after the modification treatment as the second height.

[0011] In an embodiment of the present application, it further includes: adjusting the modification process parameters to cause the modification medium to perform a modification treatment on the convex portion, where the modification process parameters include any one of the flow rate of the modification medium, the flow rate, and the duration of the modification process.

[0012] In an embodiment of the present application, the modification treatment includes any one of oxidation treatment, halogenation treatment, and conversion treatment.

[0013] In an embodiment of the present application, the modification medium includes any one of HF, Cl2, O3, BCl3, SOCl2, MoCl5, MoF6, Br2.

[0014] In an embodiment of the present application, determining whether the etching result of the first deposition layer reaches a predetermined etching target includes: measuring the thicknesses of the first deposition layer at the feature opening and on the feature sidewall, determining the maximum thickness among the thicknesses, and the third position corresponding to the maximum thickness in the depth direction of the feature; determining a first position starting from the feature opening and along the depth direction of the feature towards the feature bottom, where the first position is the position where the thickness of the first deposition layer decreases to the theoretical deposition thickness of the first deposition layer; determining a fourth position between the first position and the third position, where in the depth direction, the distance from the fourth position to the first position is equal to the distance from the fourth position to the third position; and judging whether the etching result of the first deposition layer reaches a predetermined etching target according to the thicknesses of the first deposition layer corresponding to the first position, the third position, and the fourth position respectively.

[0015] In an embodiment of the present application, determining whether the etching result of the first deposition layer reaches a predetermined etching target according to the thicknesses of the first deposition layer corresponding to the first position, the third position, and the fourth position respectively includes: calculating a first layer thickness ratio, where the first layer thickness ratio is the ratio of the thickness of the first deposition layer corresponding to the fourth position to the theoretical deposition thickness; calculating a second layer thickness ratio, where the second layer thickness ratio is the ratio of the maximum thickness to the thickness of the first deposition layer corresponding to the fourth position; and determining that the etching result of the first deposition layer reaches the predetermined etching target in response to the first layer thickness ratio and the second layer thickness ratio reaching a predetermined layer thickness ratio range.

[0016] In an embodiment of the present application, the predetermined layer thickness ratio range includes: less than or equal to 1.

[0017] In an embodiment of the present application, the etching medium includes any one of HF, CF4, NF3, C4F8, Cl2, and NH3.

[0018] In an embodiment of the present application, the first deposition layer includes any one of molybdenum metal, TiN, MoS2, nitride, oxide, and dichalcogenide.

[0019] The present application also proposes a semiconductor structure to solve the above technical problems, and the semiconductor structure is formed by using the feature filling method as described above.

[0020] The feature filling method of the present application can obtain the morphology of the first deposition layer at the feature opening in a timely or real-time manner, determine whether a convex portion is formed, and use an etching medium to etch the first deposition layer when a convex portion is formed at the feature opening, so that the first deposition layer at the feature opening is etched first relative to the first deposition layer at the feature sidewall and the feature bottom; before etching according to the feature filling method of the present application, the convex portion can be modified to further achieve selective etching of the convex portion, thereby effectively reducing or removing the convex portion, preventing the convex portion from closing the feature opening, avoiding forming holes inside the feature, and improving the feature filling rate while enhancing the chip performance. Description of the Drawings

[0021] The inclusion of the drawings is to provide a further understanding of the present application. They are incorporated and constitute a part of the present application. The drawings illustrate embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the drawings:

[0022] Figure 1 is a schematic diagram of a trench structure on a substrate;

[0023] Figure 2 is at Figure 1 a schematic diagram of a deposition layer formed in the trench structure of;

[0024] Figure 3 It is a schematic diagram of the gas flow distribution during deposition for the structure shown in Figure 2 ;

[0025] Figure 4 It is a schematic diagram showing that a convex portion is formed at the trench opening based on the structure shown in Figure 2 ;

[0026] Figure 5 It is a schematic diagram showing that the trench opening is closed based on the structure shown in Figure 4 ;

[0027] Figure 6 It is an exemplary flowchart of the feature filling method according to an embodiment of the present application;

[0028] Figure 7 It is a schematic diagram of the structure of a substrate including multiple features arranged at intervals in the feature filling method according to an embodiment of the present application;

[0029] Figure 8 It is a schematic diagram of the structure where a convex portion is formed at the feature opening in the feature filling method according to an embodiment of the present application;

[0030] Figure 9 It is an exemplary process of the modification process in the feature filling method according to an embodiment of the present application;

[0031] Figure 10 It is a schematic diagram of the structure for modification processing according to the feature filling method according to an embodiment of the present application;

[0032] Figure 11 It is a partially enlarged schematic diagram of the feature opening in the feature filling method according to an embodiment of the present application;

[0033] Figure 12 It is a schematic diagram of the process flow according to the feature filling method according to an embodiment of the present application. Detailed implementation manners

[0034] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0035] As shown in this application, unless the context clearly indicates otherwise, words such as "a", "an", "one", and / or "the" are not specific to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0036] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of this application. At the same time, it should be understood that for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the description. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0037] In the description of this application, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are usually based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing this application and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of this application; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0038] For the convenience of description, spatial relative terms such as "above", "on top of", "on the upper surface of", "above-mentioned", etc. can be used here to describe the spatial positional relationships between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to cover different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "on top of other devices or structures" will then be positioned "below other devices or structures" or "beneath other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0039] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of differentiating the corresponding components. Without additional statements, these terms have no special meaning, so it should not be construed as a limitation on the protection scope of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant according to his or her judgment, and their detailed meanings are described in the relevant parts of this description. In addition, it is required to understand this application not only through the actual terms used, but also through the meaning implied by each term.

[0040] Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of this application. It should be understood that the operations before or below do not necessarily need to be executed precisely in sequence. On the contrary, they can be executed in reverse order or simultaneously. At the same time, other operations can be added to these processes, or one or several steps can be removed from these processes.

[0041] The ALD technology has the advantage of high conformality and has good step coverage for different 3D structures such as deep holes and trenches. However, for features with a large aspect ratio, due to the flow field distribution characteristics of the gas, the concentration and probability of the gas contacting the gas at the feature opening are higher than those inside the feature, resulting in a high reaction degree at the feature opening, uneven deposition film quality, uneven thickness, and even the generation of protrusions. Figure 1 It is a schematic diagram of a trench structure on a substrate. Among them, the trench 101 has a large aspect ratio. In this application, the so-called "large aspect ratio" means that the ratio of the depth of the trench 101 to its cross-sectional width is greater than a certain value, which is determined by those skilled in the art, for example, greater than any value between 50 and 100, and this application does not limit this. Figure 2 As shown, a deposition layer 102 is deposited in the trench 101. Ideally, the deposition layer 102 formed by, for example, the ALD technology is completely conformal, that is, the deposition layer 102 is deposited evenly in thickness on the surface of the trench 101. Figure 3 As shown is a schematic diagram of the gas flow distribution during thin film deposition, where the lines with arrows represent the gas flow direction. Among them, more gas flow is contacted at the opening of the trench 101, while less gas flow is contacted at the bottom of the trench 101. Local CVD phenomena are likely to occur near the opening of the trench 101, that is, the gaseous precursor does not react in the self-limiting reaction mode of ALD in these local areas, but rather a relatively continuous chemical reaction occurs, resulting in the growth mode of the thin film in these areas being closer to CVD. The gas concentration contacted at the opening of the trench 101 is higher than that inside the trench 101, resulting in the generation of a protrusion 103 at the opening of the trench 101, asFigure 4 As shown. As the number of cycles increases, the protruding portion 103 gradually thickens and grows, which causes the opening of the groove 101 to be closed, as Figure 5 shown, resulting in the inability of gas to enter the inside of the groove 101 and generating voids 104 inside the groove 101, causing a filling rate problem, and further resulting in non-compliance of chip-related indicators such as resistivity.

[0042] To alleviate and solve the above problems, the present application proposes a feature filling method. Features refer to features with openings such as the groove 101 on the substrate. The feature filling method of the present application can enhance the conformality of thin film deposition, improve the filling rate of trenches, reduce voids, and improve the filling rate and step coverage.

[0043] Figure 6 is an exemplary flowchart of the feature filling method according to an embodiment of the present application. Refer to Figure 6 As shown, the feature filling method 600 of this embodiment includes the following steps:

[0044] Step S610: Provide a substrate including a plurality of features, the plurality of features are spaced apart on the substrate, and each feature has a feature opening, a feature sidewall, and a feature bottom respectively;

[0045] Step S620: Fill the plurality of features using the ALD process, and conformally form a first deposition layer in the plurality of features, the first deposition layer covering the feature opening, the feature sidewall, and the feature bottom;

[0046] Step S630: Obtain the morphology of the first deposition layer at the feature opening, and determine whether a convex portion is formed at the feature opening of the first deposition layer, wherein the convex portion protrudes toward the center of the feature opening;

[0047] Step S640: In response to the formation of a convex portion at the feature opening, etch the first deposition layer using an etching medium so that the first deposition layer at the feature opening is etched prior to the first deposition layer at the feature sidewall and the feature bottom; and

[0048] Step S650: Determine whether the etching result of the first deposition layer reaches a predetermined etching target, and in response to the etching result reaching the predetermined etching target, stop etching the first deposition layer and fill the plurality of features again using the ALD process to conformally form a second deposition layer in the plurality of features.

[0049] The above steps S610 to S650 will be described in detail below with reference to the accompanying drawings.

[0050] In this application, the terms "semiconductor wafer", "wafer", "substrate", and "partially fabricated integrated circuit" are used interchangeably. Those of ordinary skill in the art will understand that the term "partially fabricated integrated circuit" can refer to a silicon wafer during any stage of the many stages of integrated circuit fabrication thereon. The substrate can be patterned. The material added on top of the substrate can be patterned or can remain unpatterned. In addition, the substrate can include various semiconductor materials, such as silicon, germanium, gallium arsenide, indium phosphide, etc.

[0051] Figure 7 A schematic structural diagram of a substrate including a plurality of features arranged at intervals is shown. Refer to Figure 7 As shown, on the substrate 701, a plurality of features 710 are arranged at intervals. It should be noted that Figure 7 As shown in the cross-sectional schematic diagram, it is not used to limit the shape and size of the feature 710. The spacing between the plurality of features 710 can be equal or unequal. The feature 710 can specifically include trenches. In the accompanying drawings of this application, trenches are used as an example for illustration. Each feature 710 has a feature opening 711, a feature sidewall 712, and a feature bottom 713 respectively. It should be noted that the feature opening 711 refers to the space at the opening of the feature 710, that is, the space opened at the upper surface of the feature 710 close to the substrate 701.

[0052] Combined with Figure 7 and Figure 8 As shown, in step S620, the ALD process is used to fill the plurality of features 710, and a first deposition layer 720 is conformally formed in the plurality of features 710. The first deposition layer 720 covers the feature opening 711, the feature sidewall 712, and the feature bottom 713. Due to the good conformality of the ALD process, the first deposition layer 720 can be conformally formed on the feature 710, and has the same layer thickness at the feature opening 711, the feature sidewall 712, and the feature bottom 713. However, due to the reasons described above, an unwanted protrusion 730 will be formed at the feature opening 711. Figure 8 The protrusion 730 is shown, but it is not used to limit that it must exist at the feature opening 711 of one or more features 710.

[0053] It should be noted that this application does not limit the material used to form the first deposition layer 720 in step S620. In some embodiments, the first deposition layer 720 includes molybdenum element, that is, the first deposition layer 720 is a molybdenum-containing layer. In some embodiments, the first deposition layer 720 includes any one or a combination of metal molybdenum, TiN, MoS2, nitride, oxide, dichalcogenide.

[0054] In some embodiments, a first deposition layer 720 is formed in step S620. When the first deposition layer is molybdenum metal, any of the following precursors can be used. The precursor can be a halogen-containing Mo precursor: including but not limited to MoF6, MoCl5, MoO2Cl2, Mo(thd)2Cl2, etc. Using any of the precursors enables the feature filling method of the present application to have a wider selection method for the film properties, which is beneficial to achieving anisotropy, improving the resistivity, and increasing the growth rate, etc.

[0055] It should be noted that the ALD process in step S620 can be a PEALD process or a pure thermal chemical reaction ALD process.

[0056] In step S630, the morphology of the first deposition layer 720 at the feature opening 711 can be obtained in an image manner. In some embodiments, step S630 includes: using a Transmission Electron Microscope (TEM) to obtain the morphology at this location. For example, after step S620, a sample including the region of interest is obtained from the substrate, a TEM section is made according to the sample, and the internal structure of the TEM section is observed using TEM. Among them, the region of interest is the region including the morphology of the first deposition layer 720 at the feature opening 711. As Figure 8 shown, it can be visually seen by the naked eye that protrusions 730 are formed at the feature openings 711 of multiple features 710, and each protrusion 730 protrudes towards the center of the feature opening 711. According to such protrusions 730, after multiple ALD processes, as the protrusions 730 thicken and grow, it is very likely that the feature openings 711 of the features 710 will be closed, thereby forming holes or gaps inside the features 710. <T

[0057] If it is determined in step S630 that a protrusion 730 is formed at the feature opening 711 of the first deposition layer 720 in the feature 710, then in step S640, the first deposition layer 720 is etched using an etching medium. The etching medium is a substance with etching ability. The present application does not limit the etching medium. In some embodiments, the etching medium includes any one or a combination of HF, CF4, NF3, C4F8, Cl2, NH3. These etching media can be used simultaneously in the PEALD process and the pure thermal chemical reaction ALD process, which means that in the feature filling method of the present application, the deposition process and the etching process can be carried out in the same chamber.

[0058] In step S640, the first deposition layer 720 is etched such that the first deposition layer 720 at the feature opening 711 is etched prior to the first deposition layer 720 at the feature sidewall 712 and the feature bottom 713. In this way, the protrusion 730 can be selectively etched, thereby preventing the protrusion 730 from closing the feature 710, avoiding the formation of holes inside the feature 710, and improving the filling rate and chip performance.

[0059] It should be noted that during the process with multiple cycle deposition processes, step S630 and S640 can be executed after each deposition of a first deposition layer 720, or can be executed once after depositing several first deposition layers 720.

[0060] Continue to refer to Figure 6 , after step S640, step S650 is executed to determine whether the etching result of the first deposition layer 720 reaches a predetermined etching target. In response to the etching result reaching the predetermined etching target, the etching of the first deposition layer 720 is stopped, and the ALD process is used again to fill multiple features 710, and a second deposition layer (not shown in the figure) is conformally formed in the multiple features 710. According to step S650, the subsequent formed second deposition layer can be conformal to the feature 710, improving the filling rate of the feature 710.

[0061] According to the above steps S610 - S650, during the filling process of the feature 710, the presence of the protrusion 730 in the deposition layer can be detected in a timely manner, and the first deposition layer 720 is etched with an etching medium, thereby timely reducing or eliminating the protrusion 730, preventing the feature opening 711 from being closed, avoiding the formation of holes or gaps inside the feature 710, and improving the filling rate and chip performance. At the same time, the feature filling method of the present application does not require moving the substrate or replacing the chamber throughout the process, and has high processing efficiency.

[0062] Figure 9 is an exemplary process of the modification process in the feature filling method of an embodiment of the present application. As Figure 9 shown, in some embodiments, before step S640, the feature filling method of the present application further includes:

[0063] Step S910: Modify at least part of the first deposition layer with a modification medium, where at least part of the first deposition layer includes the first deposition layer at the feature opening; and

[0064] Step S920: Determine whether the modification result of at least part of the first deposition layer reaches a predetermined modification target. In response to the modification result reaching the predetermined modification target, stop the modification process.

[0065] In step S910, the modification medium refers to a medium that can change the properties of the first deposition layer 720. In some embodiments, the position where the modification medium is to be provided can be controlled by controlling the direction of the spraying device, so that the modification medium can be selectively provided at some regions in the first deposition layer 720.

[0066] The modification treatment can also be referred to as activation treatment or conversion treatment. In some embodiments, the modification treatment includes any one of oxidation treatment (Oxidation), halogenation treatment (Halogenation), and conversion treatment (Conversion). Corresponding to the oxidation treatment, the modification medium includes oxygen-containing elements, such as O3, etc. It should be understood that the halogenation treatment includes fluorination treatment (Fluorination). For the fluorination treatment, the modification medium includes fluorine-containing elements, such as HF, MoF6, Br2, etc. For other halogenation treatments, the modification medium includes halogen-containing elements, such as Cl, for example, Cl2, SOCl2, MoCl5, BCl3, etc. The modification medium in the conversion treatment includes BCl3, etc. The conversion process includes, for example, substitution, that is, one substance is replaced by another substance through a substitution reaction. In one embodiment, molybdenum in the first deposition layer 720 is replaced by boron by using BCl3.

[0067] Figure 10 A schematic structural diagram showing the modification treatment of at least part of the first deposition layer 720 using the modification medium is shown. Here, at least part of the first deposition layer 720 refers to some regions in the first deposition layer 720, and this part of the region is called the target region. The target region includes the first deposition layer 720 at the feature opening 711, and at least part of the region of the first deposition layer 720 on the upper surface of the substrate. Since the convex portion 730 is located at the feature opening 711, therefore, at least part of the first deposition layer 720 affected by the modification medium includes the convex portion 730. It can be understood that the convex portion 730 has a certain height in the depth direction D1 of the feature 710. Therefore, the part of the feature sidewall 712 near the feature opening 711 of the convex portion 730, and the part of the upper surface of the first deposition layer 720 near the feature opening 711, both protrude towards the center of the feature opening 711.

[0068] As Figure 10As shown, after the modification treatment, a modified layer 740 is formed on the surface of the target area of the first deposition layer 720, indicating the influence range of the modification medium. The modified layer 740 is formed by the reaction of some materials near the surface layer in the first deposition layer 720 with the modification medium. Assume that the thickness of the first deposition layer 720 is d0. After modification, in this target area, the total thickness of the first deposition layer 720 and the modified layer 740 is d1. d1 may be greater than, equal to, or less than d0. After the modification treatment, the material in the target area of the first deposition layer 720 is changed into a new material, which has an etching selectivity compared with the material of the original first deposition layer 720. That is, an etching medium can be selected. When etching the substrate with this etching medium, only the modified new material can be etched, and the original first deposition layer 720 cannot be etched. In this way, after modification, in the etching process of step S640, the target area modified on the first deposition layer 720 can be etched, that is, the target area including the convex portion 730 can be selectively etched, so as to reduce the convex portion 730 without etching other areas of the feature 710 and not affecting the morphology of other areas. In addition, after modification, the interface between the modified layer 740 and the first deposition layer 720 is clear, which is beneficial to evaluating the modification effect.

[0069] In some embodiments, the modification process further includes: adjusting the modification process parameters to modify the convex portion 730 with the modification medium, where the modification process parameters include any one of the flow rate, flow volume of the modification medium, and the duration of the modification process. By adjusting the modification process parameters, the modification medium can mainly act on the convex portion 730, further improving the etching selectivity of the area where the convex portion 730 is located. For example, by controlling the flow rate and process duration of the modification medium within a certain range, the modification medium only acts on the upper surface of the first deposition layer 720, and no modification medium or only a small amount of modification medium enters the feature 710.

[0070] For the solution without using the modification treatment, when etching the first deposition layer 720 at the convex portion 730, the first deposition layer 720 at the sidewall feature 712 may become rough, forming some burr-like structures. In the above embodiments, by performing the modification treatment, the etching selectivity ratio of the area where the convex portion 730 is located is improved, so that the subsequent etching process can accurately remove the convex portion 730, reducing burrs, uneven etching, and other problems caused by anisotropic etching in the feature 710.

[0071] The following combines Figure 10 to illustrate step S920. In some embodiments, step S920 includes:

[0072] Step S921: Before performing the modification treatment, measure the first height h1 of the convex portion 730 in the depth direction D1 of the feature 710;

[0073] Step S922: After performing the modification treatment, measure the second height h2 of at least part of the first deposition layer 720 in the depth direction D1 of the feature 710;

[0074] Step S923: Calculate the height ratio Rh, where the height ratio Rh is the ratio of the first height h1 to the second height h2; and

[0075] Step S924: If the height ratio Rh reaches the predetermined height ratio range, determine that the modification result of at least part of the first deposition layer 720 reaches the predetermined modification target.

[0076] It should be noted that Figure 10 the h2 shown is greater than h1, which is only an example. In this example, after the modification, the thickness of the first deposition layer 720 increases.

[0077] According to Step S923, Rh = h1 / h2. In some embodiments, the predetermined height ratio range includes: 1 ± δ, where 0 < δ ≤ 0.5.

[0078] In some preferred embodiments, when the predetermined modification target is reached, Rh is approximately equal to 1, or a value within a small range near 1. For example, 0.8 < Rh < 1.2, such as Rh being equal to 0.8, 0.9, 1, 1.1, 1.2, etc.

[0079] Ideally, after the modification treatment, h2 = h1, that is, Rh = 1, and all the target areas are converted into new materials, then the entire convex portion 730 is modified. Then, in the subsequent etching step, ideal etching can be performed on the entire convex portion 730. Assume that after the modification treatment, h2 << h1, that is, Rh is a value much greater than 1, which indicates insufficient activation, and the modification result of at least part of the first deposition layer 720 does not reach the predetermined modification target, and further modification treatment is required. Assume that after the modification treatment, h2 >> h1, that is, Rh is a value much less than 1 and greater than 0, which indicates over-modification, and this will cause the first deposition layer 720 on the sidewall 712 and even the bottom 713 of the feature to be modified and will also be etched in the subsequent steps, resulting in over-etching. Therefore, both insufficient modification and over-modification are not desirable. By setting the predetermined height ratio range, it is possible to continue the modification treatment when the modification is insufficient and prevent over-modification and stop the modification treatment in a timely manner.

[0080] In some embodiments, measuring the first height h1 of the convex portion 730 in the depth direction D1 of the feature 710 includes:

[0081] Step S9211: Measure the thickness of the first deposition layer 720 on the feature opening 711 and the feature sidewall 712, where the thickness varies along the depth direction D1 of the feature 710. The variation in thickness also indicates the presence of the convex portion 730.

[0082] Step S9212: Starting from the feature opening 711, determine a first position P1 along the depth direction D1 of the feature 710 towards the feature bottom 713. The first position P1 is the position where the thickness of the first deposition layer 720 decreases to the theoretical deposition thickness of the first deposition layer 720; and

[0083] Step S9213: Take the distance between the first position P1 and the first upper surface 721 of the first deposition layer 720 as the first height h1;

[0084] In some embodiments, measuring the second height h2 of at least part of the first deposition layer 720 in the depth direction D1 of the feature 710 includes:

[0085] Step S9221: Along the depth direction D1 of the feature 710, determine a second position P2 of at least part of the first deposition layer 720 closest to the feature bottom 713 after the modification treatment. Take the distance between the second position P2 and the second upper surface 722 of the first deposition layer 720 after the modification treatment as the second height h2.

[0086] It should be noted that the first upper surface 721 of the first deposition layer 720 is the upper surface before the modification treatment, and the second upper surface 722 of the first deposition layer 720 is the upper surface after the modification treatment.

[0087] It should be noted that the theoretical deposition thickness of the first deposition layer 720 in step S9212 is based on actual process requirements. Generally speaking, it is the layer thickness of the first deposition layer 720 that is expected to be obtained when depositing the first deposition layer 720. At step S9212, the position where the thickness of the first deposition layer 720 decreases to the theoretical deposition thickness is not limited to the position where the thickness just becomes the theoretical deposition thickness. In actual situations, the thickness change of the first deposition layer 720 on the feature sidewall 712 may fluctuate. Therefore, the thickness of the first deposition layer 720 decreasing to the theoretical deposition thickness can be expressed as the thickness of the first deposition layer 720 being basically stable around the theoretical deposition thickness, allowing for a certain error range.

[0088] At step S9213, before the modification treatment, the first upper surface 721 of the first deposition layer is the upper surface of the substrate in the current process. At step S9221, after the modification treatment, the second upper surface 722 of the first deposition layer 720 is the upper surface of the substrate in the current process.

[0089] The following is combined with Figure 11Describe step S650. In some embodiments, determining whether the etching result of the first deposition layer 720 reaches a predetermined etching target in step S650 includes:

[0090] Step S651: Measure the thickness of the first deposition layer 720 at the feature opening 711 and the feature sidewall 712, determine the maximum thickness a among the thicknesses, and the third position P3 corresponding to the maximum thickness a in the depth direction D1 of the feature 710;

[0091] Step S652: Starting from the feature opening 711, determine the first position P1 along the depth direction D1 of the feature 710 towards the feature bottom 713. The first position P1 is the position where the thickness of the first deposition layer 720 decreases to the theoretical deposition thickness c of the first deposition layer 720;

[0092] Step S653: Determine the fourth position P4 between the first position P1 and the third position P3. Among them, in the depth direction D1, the distance from the fourth position P4 to the first position P1 is equal to the distance from the fourth position P4 to the third position P3; and

[0093] Step S654: Determine whether the etching result of the first deposition layer 720 reaches a predetermined etching target according to the thicknesses of the first deposition layer 720 corresponding to the first position P1, the third position P3, and the fourth position P4 respectively.

[0094] In steps S651 - S654, the thicknesses of each position on the first deposition layer 720 can be obtained based on TEM slices. Other means can also be used to measure the corresponding thicknesses. This application does not limit this. The method for determining the first position P1 in step S652 is similar to the method for determining the first position P1 in step S9212. The relevant content above can be used to illustrate step S652 and will not be elaborated here. In addition, since the third position P3 has been determined in step S651, in step S652, the first position P1 can be determined starting from the third position P3 downwards. In this way, the calculation efficiency can be improved for the specific implementation of the algorithm.

[0095] According to steps S651 - S654, the thicknesses c, a, and b of the first deposition layer 720 corresponding to the first position P1, the third position P3, and the fourth position P4 respectively can be obtained. Judging whether the etching result of the first deposition layer 720 reaches a predetermined etching target based on the thicknesses at these three positions, rather than simply judging based on one position (such as P3), can make a more accurate judgment on the etching result, so that after etching, the convex portion 730 at the feature opening 711 is reduced, and at the same time, the morphology of the first deposition layer 720 on the feature sidewall 712 remains normal.

[0096] In some embodiments, step S654 includes the following steps:

[0097] Step S6541: Calculate the first layer thickness ratio Rt1. The first layer thickness ratio Rt1 is the ratio of the thickness b corresponding to the first deposition layer 720 at the fourth position P4 to the theoretical deposition thickness c.

[0098] Step S6542: Calculate the second layer thickness ratio Rt2. The second layer thickness ratio Rt2 is the ratio of the maximum thickness a to the thickness b corresponding to the first deposition layer 720 at the fourth position P4; and

[0099] Step S6543: In response to the first layer thickness ratio Rt1 and the second layer thickness ratio Rt2 reaching a predetermined layer thickness ratio range, determine that the etching result of the first deposition layer 720 reaches a predetermined etching target.

[0100] In some embodiments, steps S6541 - S6543 can be executed by a main body such as a computer, a terminal device, a controller, etc. The present application does not limit this. In step S6541, the first layer thickness ratio value Rt1 = b / c can be obtained. In step S6542, the second layer thickness ratio Rt2 = a / b can be obtained.

[0101] In some embodiments, the predetermined layer thickness ratio range includes: less than or equal to 1. If Rt_{1}≤1 and Rt_{2}≤1, it indicates that the feature opening 711 is etched out and does not block the subsequent gas from entering the interior of the feature 710, and thus the etching of the first deposition layer 720 can be stopped. If Rt_{1}>1 and / or Rt_{2}>1, it indicates that the etching degree of the opening is insufficient, and there is still a possibility that the subsequent gas is blocked from entering the interior of the feature 710, then the first deposition layer 720 needs to be continuously etched.

[0102] In some embodiments, step S640 further includes: adjusting the etching parameters to adjust the etching degree of the first deposition layer 720. The etching parameters include any one of flow rate, flow velocity, process temperature, process duration, and chamber pressure. In practical applications, in the experimental stage, by repeatedly executing the foregoing steps S610 - S650 and adjusting the etching parameters as needed during this process, the corresponding etching parameters can be obtained for the target process, so that the etching parameters determined through experiments can be used in the subsequent mass production process to achieve the effect of batch removing the protrusions.

[0103] It should be noted that in combination with Figure 8 , there are multiple features 710 on the substrate 701, and the morphologies of the protrusions 730 at the feature openings 711 of each feature 710 may be different. Therefore, to judge whether the etching or modification reaches the target as a whole, at least the following three methods can be adopted:

[0104] (1) Take the average value of multiple measurements of a and c in each feature 710;

[0105] (2)Measure the above-mentioned respective parameters (h1, h2, a, b, c) of each feature 710, and respectively take the mean value of each parameter for multiple features 710 to obtain the respective mean values of h1, h2, a, b, c. Then calculate Rh, Rt1, and Rt2 based on these mean values.

[0106] (3)Measure the above-mentioned respective parameters (h1, h2, a, b, c) of each feature 710, calculate Rh, Rt1, and Rt2 of each feature 710, and then respectively take the mean value of multiple Rh, Rt1, and Rt2.

[0107] According to such a scheme, using the data from multiple or all features 710 on the substrate 701 to determine whether etching or modification reaches the target is beneficial to removing the influence of the convex portion 730 on the feature 710 as a whole.

[0108] Figure 12 It is a process flow schematic diagram of a feature filling method according to an embodiment of the present application. Taking this process flow as an example, the application scenario of the feature filling method of the present application is described:

[0109] In the whole process, a carrier gas is introduced, and the carrier gas can be N2, Ar, He, etc. This process flow sequentially executes the following stages:

[0110] (1)Deposition stage: Introduce a precursor. The precursor contains molybdenum, such as MoF6, MoCl5, MoO2Cl2, Mo(thd)2Cl2, etc. mentioned above. The process duration is 0.01 - 20 s.

[0111] (2)Purge stage.

[0112] (3)Reduction stage: Introduce a reducing agent, such as H2, N2H2, NH۳, H*, SiH4, etc. The process duration is 1 - 20 s.

[0113] (4)Purge stage.

[0114] (⑤)Surface modification: Introduce an activator, such as O3, O2, halogenating agent. The process duration is 1 - 20 s.

[0115] (6)Purge stage.

[0116] (⑦)Surface conversion: Introduce a conversion agent, such as BCl3, BF3, etc. The process duration is 1 - 20 s.

[0117] (⑧)Purge stage.

[0118] (⑨)Removal: Introduce an etchant, such as F, Cl, Br, CF4, Ar*, NF3, etc. The process duration is 1 - 20 s.

[0119] (⑩)Purge stage.

[0120] Subsequently, the above 10 stages are repeatedly executed.

[0121] This application also proposes a semiconductor structure, which is formed by using the feature filling method described in the foregoing part of this application. The foregoing description content and drawings can be used to illustrate the semiconductor structure of this application, and will not be elaborated herein.

[0122] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only an example and does not constitute a limitation to this application. At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0123] In some embodiments, numbers describing the components and attribute quantities are used. It should be understood that such numbers used for the description of embodiments are modified by the modifiers "about", "approximately", or "substantially" in some examples. Unless otherwise stated, "about", "approximately", or "substantially" indicate that the said numbers allow a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification are approximate values, and these approximate values can change according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the scope breadth in some embodiments of this application are approximate values, in specific embodiments, such numerical settings are made as precise as possible within the feasible range.

Claims

1. A feature filling method, characterized in that: include: Providing a substrate comprising a plurality of features, wherein the plurality of features are spaced apart on the substrate, each feature having a feature opening, a feature sidewall, and a feature bottom; Filling the plurality of features using an ALD process to conformally form a first deposition layer in the plurality of features, wherein the first deposition layer covers the feature openings, the feature sidewalls, and the feature bottoms; Acquiring a morphology of the first deposition layer at the characteristic opening, and determining whether a convex portion is formed on the first deposition layer at the characteristic opening, wherein the convex portion protrudes toward a center of the characteristic opening; In response to a protrusion being formed at the feature opening, etching the first deposition layer using an etching medium so that the first deposition layer at the feature opening is etched earlier than the first deposition layer at the feature sidewall and the feature bottom; and determining whether an etching result of the first deposited layer reaches a predetermined etching target, and in response to the etching result reaching the predetermined etching target, stopping etching the first deposited layer, and again employing the ALD process to fill the plurality of features, thereby conformally forming a second deposited layer in the plurality of features; Before etching the first deposition layer using the etching medium, the method further includes: Performing a modification process on at least a portion of the first deposition layer using a modifying medium, wherein at least a portion of the first deposition layer includes the first deposition layer at the feature opening; and determining whether a modification result of at least a portion of the first deposition layer reaches a predetermined modification target, and stopping the modification process in response to the modification result reaching the predetermined modification target; Wherein, the determining whether the modification result of at least a portion of the first deposition layer reaches a predetermined modification target includes: Before performing the modification process, measuring a first height of the protrusion in the depth direction of the feature; After performing the modification process, measuring a second height of at least a portion of the first deposited layer in a depth direction of the feature; calculating a height ratio, the height ratio being a ratio of the first height to the second height; and If the height ratio reaches a predetermined height ratio range, it is determined that the modification result of at least a portion of the first deposition layer reaches a predetermined modification target.

2. The feature filling method according to claim 1, wherein: The predetermined height ratio range includes: 1±δ, 0<δ≤0.

5.

3. The feature filling method according to claim 1, wherein: Measuring a first height of the protrusion in a depth direction of the feature includes: measuring a thickness of the first deposition layer at the feature opening and the feature sidewalls, wherein the thickness varies along a depth direction of the feature; Determining a first position from the feature opening along a depth direction of the feature toward the feature bottom, the first position being a position where a thickness of the first deposition layer decreases to a theoretical deposition thickness of the first deposition layer; and taking the distance between the first position and the first upper surface of the first deposition layer as the first height; Measuring a second height of at least a portion of the first deposited layer in a depth direction of the feature, comprising: Along the depth direction of the feature, determine a second position where at least a portion of the first deposition layer after modification is closest to the bottom of the feature, and use the distance between the second position and a second upper surface of the first deposition layer after modification as the second height.

4. The feature filling method according to claim 1, wherein: Also includes: The modification process parameters are adjusted so that the modification medium performs modification processing on the convex portion, wherein the modification process parameters include any one of the flow rate and flow rate of the modification medium and the duration of the modification process.

5. The feature filling method according to claim 1, wherein: The modification treatment includes any of oxidation treatment, halogenation treatment and conversion treatment.

6. The feature filling method according to claim 1, wherein: The modifying medium includes any one of HF, Cl2, O3, BCl3, SOCl2, MoCl5, MoF6, and Br2.

7. The feature filling method according to claim 1, wherein: The determining whether the etching result of the first deposition layer reaches a predetermined etching target includes: measuring the thickness of the first deposition layer at the feature opening and the feature sidewall, determining a maximum thickness among the thicknesses, and a third position corresponding to the maximum thickness in the depth direction of the feature; Determine a first position from the feature opening along the depth direction of the feature toward the feature bottom, the first position being a position where the thickness of the first deposition layer decreases to a theoretical deposition thickness of the first deposition layer; determining a fourth position between the first position and the third position, wherein a distance from the fourth position to the first position in the depth direction is equal to a distance from the fourth position to the third position; and Whether the etching result of the first deposition layer reaches a predetermined etching target is determined according to the thicknesses of the first deposition layer at the first position, the third position, and the fourth position.

8. The feature filling method according to claim 7, wherein: The determining whether the etching result of the first deposition layer reaches a predetermined etching target according to the thicknesses of the first deposition layer at the first position, the third position, and the fourth position, respectively, includes: calculating a first layer thickness ratio, where the first layer thickness ratio is a ratio of a thickness of the first deposition layer corresponding to the fourth position to the theoretical deposition thickness; calculating a second layer thickness ratio, where the second layer thickness ratio is a ratio of the maximum thickness to a thickness of the first deposition layer corresponding to the fourth position; and In response to the first layer thickness ratio and the second layer thickness ratio reaching a predetermined layer thickness ratio range, it is determined that the etching result of the first deposition layer reaches a predetermined etching target.

9. The feature filling method according to claim 8, wherein: The predetermined layer thickness ratio range includes: less than or equal to 1.

10. The feature filling method according to claim 1, wherein: The etching medium includes any one of HF, CF4, NF3, C4F8, Cl2, and NH3.

11. The feature filling method according to claim 1, wherein: The first deposition layer includes any one of metal molybdenum, TiN, MoS2, nitride, oxide, and dichalcogenide.

12. A semiconductor structure, characterized in that: The semiconductor structure is formed by using the feature filling method according to any one of claims 1 to 11.

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