Semiconductor structure and manufacturing method thereof

Abstract

This disclosure provides a semiconductor structure and a method for manufacturing the same. The method includes: providing a substrate in which at least one trench is formed; forming a first barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate; the first barrier sublayer comprising a barrier material in which a first crystal orientation accounts for a greater than a first preset value among all crystal orientations; forming a second barrier sublayer on the first barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate; the second barrier sublayer comprising a barrier material in which a second crystal orientation accounts for a greater than a second preset value among all crystal orientations; wherein the first crystal orientation and the second crystal orientation are different.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and more particularly to a semiconductor structure and a method for manufacturing the same. Background Technology

[0002] As semiconductor structures continue to shrink in size, the aspect ratios of contact holes and vias are constantly increasing, posing ongoing challenges to the chemical vapor deposition (CVD) process for tungsten (W). In the field of semiconductor technology, tungsten CVD is commonly used to realize metal interconnects for contact holes or vias.

[0003] Currently, during chemical vapor deposition of tungsten, the tungsten metal may hang above contact holes or vias, causing voids or seams within the tungsten metal in the contact holes or vias, resulting in an overhang effect. This overhang effect can degrade the electrical performance of semiconductor structures and reduce product yield.

[0004] Therefore, there is an urgent need to improve the manufacturing methods of semiconductor structures to increase product yield. Summary of the Invention

[0005] In view of this, the present disclosure provides a semiconductor structure and a method for manufacturing the same.

[0006] To achieve the above objectives, the technical solution disclosed herein is implemented as follows:

[0007] In a first aspect, embodiments of this disclosure provide a method for manufacturing a semiconductor structure, the method comprising:

[0008] A substrate is provided in which at least one trench is formed;

[0009] A first barrier sublayer is formed on the sidewalls and bottom of the trench and on the surface of the substrate; the first barrier sublayer includes a barrier material in which the proportion of a first crystal orientation in all crystal orientations is greater than a first preset value;

[0010] A second barrier sublayer is formed on the sidewalls and bottom of the trench and on the surface of the substrate of the first barrier sublayer; the second barrier sublayer includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein the first crystal orientation and the second crystal orientation are different.

[0011] In some embodiments, forming a first barrier sublayer on the sidewalls and bottom of the trench and on the substrate surface includes:

[0012] The first reactant and the second reactant are reacted on the sidewalls and bottom of the trench and on the surface of the substrate to form a first barrier sublayer;

[0013] The formation of a second barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate includes:

[0014] A first reactant and a second reactant are reacted on the sidewalls and bottom of the trench and on the surface of the substrate to form a second barrier layer;

[0015] The ratio between the first reactant and the second reactant in the formation of the first barrier sublayer is different from the ratio between the first reactant and the second reactant in the formation of the second barrier sublayer.

[0016] In some embodiments, the material of the first barrier sublayer includes titanium nitride (TiN); forming the first barrier sublayer on the sidewalls and bottom of the trench and on the substrate surface includes:

[0017] A first barrier layer is formed by reacting ammonia (NH3) with a first gas flow rate and titanium tetrachloride (TiCl4) with a second gas flow rate on the sidewalls and bottom of the trench and on the surface of the substrate; wherein the ratio between the first gas flow rate and the second gas flow rate is less than 30.

[0018] In some embodiments, the material of the second barrier sublayer includes TiN; forming the second barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate includes:

[0019] A second barrier layer is formed by reacting a first reactant NH3 with a third gas flow rate and a second reactant TiCl4 with a fourth gas flow rate on the sidewalls and bottom of the trench and on the surface of the substrate; wherein the ratio between the third gas flow rate and the fourth gas flow rate is greater than 30.

[0020] In some embodiments, the formation of the first barrier sublayer has a first reaction time, the formation of the second barrier sublayer has a second reaction time, and the ratio between the first reaction time and the second reaction time is greater than 10.

[0021] In some embodiments, the first barrier sublayer and the second barrier sublayer together form a barrier layer, the thickness of which is 2 nm to 20 nm.

[0022] In some embodiments, the first crystal orientation is (200) crystal orientation and the second crystal orientation is (111) crystal orientation.

[0023] In some embodiments, after forming a second barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate, the manufacturing method further includes:

[0024] A metallic material layer is formed on the sidewalls and bottom of the trench and on the second barrier layer on the surface of the substrate.

[0025] In some embodiments, forming a metallic material layer on the sidewalls and bottom of the trench and on the second barrier sublayer of the substrate surface includes:

[0026] A layer of active atoms is formed on the second barrier sublayer using a third reactant;

[0027] The fourth reactant reacts with the active atom layer to form a metal nucleation layer on the second barrier sublayer;

[0028] The fourth and fifth reactants are used to react and form a metal bulk layer on the metal nucleation layer.

[0029] In some embodiments, the third reactant comprises diborane (B₂H₆), and the active atom layer comprises a boron atom layer; and / or,

[0030] The fourth reactant includes tungsten hexafluoride (WF6); and / or,

[0031] The fifth reactant includes hydrogen gas (H2).

[0032] In a second aspect, embodiments of this disclosure provide a semiconductor structure, the semiconductor structure comprising:

[0033] A substrate having at least one trench formed therein;

[0034] A first barrier sublayer covers the sidewalls and bottom of the trench and the surface of the substrate; the first barrier sublayer includes a barrier material in which the proportion of a first crystal orientation in all crystal orientations is greater than a first preset value;

[0035] The second barrier sublayer covers the sidewalls and bottom of the trench and the surface of the substrate of the first barrier sublayer; the second barrier sublayer includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein the first crystal orientation and the second crystal orientation are different;

[0036] A metal material layer that covers the second barrier sublayer and fills the trench.

[0037] In some embodiments, the first barrier sublayer and the second barrier sublayer together form a barrier layer, the thickness of which is 2 nm to 20 nm.

[0038] In some embodiments, the materials of the first barrier sublayer and the second barrier sublayer both include TiN; the first crystal orientation is (200) and the second crystal orientation is (111).

[0039] In some embodiments, the material of the metal material layer includes tungsten (W).

[0040] This disclosure provides a semiconductor structure and its manufacturing method. In this embodiment, a first barrier layer with a first crystal orientation ratio greater than a first preset value is first formed on the sidewalls and bottom of the trench and on the substrate surface. Then, a second barrier layer with a second crystal orientation ratio greater than a second preset value is formed. Utilizing the good step coverage of the first barrier layer with the first crystal orientation, and the fact that the second barrier layer with the second crystal orientation is more conducive to the formation of a metal nucleation layer in subsequent processes, forming first and second barrier layers with different crystal orientations can reduce the probability of voids or seams appearing in the trench filling material, thereby improving the electrical performance of the semiconductor structure and ultimately increasing product yield. Attached Figure Description

[0041] Figure 1 A schematic cross-sectional structure of a titanium nitride layer is provided as an example.

[0042] Figure 2 This is a schematic cross-sectional structure diagram of a chemical vapor deposition process for tungsten metal, provided as an example.

[0043] Figure 3 Here is a flowchart illustrating the process of forming a titanium nitride layer as an example;

[0044] Figure 4 Here is an example of an X-ray diffraction pattern of a titanium nitride layer;

[0045] Figure 5 A schematic flowchart illustrating a method for manufacturing a semiconductor structure according to an embodiment of this disclosure;

[0046] Figure 6 A schematic cross-sectional view of the first and second barrier sublayers provided in an embodiment of this disclosure;

[0047] Figure 7A A flowchart illustrating the formation of a first barrier sublayer provided in an embodiment of this disclosure;

[0048] Figure 7B A flowchart illustrating the formation of a second barrier sublayer provided in an embodiment of this disclosure;

[0049] Figure 8 X-ray diffraction patterns of titanium nitride formed under different ammonia gas flow rates;

[0050] Figure 9 X-ray diffraction patterns of titanium nitride with different crystal orientations;

[0051] Figure 10 Electron micrographs of titanium nitride with different crystal orientations;

[0052] Figure 11 The graph shows the relationship between the step coverage of titanium nitride and the gas flow rate of titanium tetrachloride.

[0053] Figure 12 A schematic cross-sectional structure diagram of the process of forming a metal material layer provided in an embodiment of this disclosure;

[0054] Figure 13A This is a schematic diagram of the decomposition of diborane on the surface of titanium nitride with the (111) crystal orientation;

[0055] Figure 13B The activation energy and reaction energy are those for the decomposition of diborane on the surface of titanium nitride with the (111) crystal orientation.

[0056] Figure 13C A schematic diagram showing the surface decomposition of diborane on titanium nitride in other crystal orientations;

[0057] Figure 13D The activation energy and reaction energy are those for the surface decomposition of diborane on titanium nitride in other crystal orientations.

[0058] Figure 14 This is a schematic diagram illustrating the principle of forming a metal nucleation layer according to an embodiment of the present disclosure;

[0059] Figure 15 This is a cross-sectional schematic diagram of a semiconductor structure provided in an embodiment of this disclosure. Detailed Implementation

[0060] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0061] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without one or more of these details. In other instances, to avoid confusion with this disclosure, certain technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0062] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0063] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this disclosure, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this disclosure.

[0064] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0065] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0066] To fully understand this disclosure, detailed steps and structures will be presented in the following description to illustrate the technical solutions of this disclosure. Preferred embodiments of this disclosure are described in detail below; however, other embodiments may also be implemented in addition to these detailed descriptions.

[0067] refer to Figure 1 , Figure 1 This is a schematic cross-sectional view of a titanium nitride layer as an example. Figure 1 As shown, the process of forming the titanium nitride layer 14 may include the following steps: trenches 12 are formed in the substrate 10 (e.g., Figure 1 (shown in the dashed box); a titanium nitride layer 14 is formed on the sidewalls and bottom of the trench 12 and on the surface of the substrate 10.

[0068] Typically, a titanium nitride layer is deposited before chemical vapor deposition of metallic tungsten. This serves two purposes: firstly, it prevents some of the reactants from eroding the substrate during tungsten deposition; secondly, it also prevents the peeling of metallic tungsten.

[0069] refer to Figure 2 , Figure 2 This is a schematic cross-sectional view of a chemical vapor deposition process for tungsten metal, provided as an example. Figure 2 As shown in Figure (a), a soak layer 16 is formed on the sidewalls and bottom of the trench 12 and on the titanium nitride layer 14 on the surface of the substrate 10, for example, using diborane (B2H6) for wetting; Figure 2 As shown in Figure (b), a tungsten nucleation layer 18 is formed on the sidewalls and bottom of the trench 12 and on the wetting layer 16 on the surface of the substrate 10, for example, by reacting diborane and tungsten hexafluoride (WF6); Figure 2 As shown in Figure (c), a tungsten bulk layer 20 is formed on the sidewalls and bottom of the trench 12 and on the tungsten nucleation layer 18 on the surface of the substrate 10; for example, a reaction is carried out using hydrogen (H2) and tungsten hexafluoride. It should be noted that... Figure 2 Figure (c) also illustrates that pores 22 are formed in the tungsten body layer 20.

[0070] Current chemical vapor deposition (CVD) processes for tungsten mainly consist of three steps: First, the substrate is wetted with diborane for a relatively long time to promote tungsten nucleation; second, tungsten hexafluoride is reduced with diborane and introduced into the cavity in a pulsed manner to deposit the tungsten nucleation layer; third, tungsten hexafluoride is reduced with hydrogen and the tungsten bulk layer is deposited by CVD, i.e., hydrogen and tungsten hexafluoride gases are introduced into the cavity simultaneously to deposit the tungsten bulk layer.

[0071] refer to Figure 3 , Figure 3This is a flowchart illustrating the process of forming a titanium nitride layer as an example. Figure 3 As shown, ammonia (NH3) with a gas flow rate of B1 is carried by a carrier gas (e.g., nitrogen (N2)) with a gas flow rate of D1, and titanium tetrachloride (TiCl4) with a gas flow rate of A1 is carried by a carrier gas with a gas flow rate of C1 to form a titanium nitride layer 14.

[0072] refer to Figure 4 , Figure 4 The X-ray diffraction pattern of a titanium nitride layer is provided as an example. Figure 4 The X-ray diffraction pattern is shown with the horizontal axis representing 2θ, in degrees (°); and the vertical axis representing intensity. Figure 4 The diffraction peaks of the silicon substrate and the diffraction peaks of the titanium nitride layer in four different crystal orientations are also shown, namely, (111) crystal orientation, (200) crystal orientation, (220) crystal orientation and (222) crystal orientation.

[0073] Currently, during chemical vapor deposition of tungsten, the resulting titanium nitride layer has a mixed crystal orientation, meaning the tungsten may hang over contact holes or vias, causing voids or seams within the holes or vias, resulting in a dangling effect. This dangling effect can degrade the electrical performance of semiconductor structures, reducing product yield.

[0074] In view of this, the present disclosure provides a semiconductor structure and a method for manufacturing the same.

[0075] refer to Figure 5 and Figure 6 , Figure 5 This is a schematic flowchart illustrating a method for manufacturing a semiconductor structure according to an embodiment of this disclosure. Figure 6 A cross-sectional structural diagram of the first and second barrier sublayers provided in the embodiments of this disclosure. The following will be combined with... Figure 5 and Figure 6 The process of forming a first barrier sublayer and a second barrier sublayer on the sidewalls and bottom of the trench and on the substrate surface is described in detail.

[0076] like Figure 5 As shown, this disclosure provides a method for manufacturing a semiconductor structure, the method comprising:

[0077] Step S501: Provide a substrate in which at least one trench is formed;

[0078] Step S502: A first barrier sublayer is formed on the sidewalls and bottom of the trench and on the substrate surface; the first barrier sublayer includes a barrier material whose proportion of the first crystal orientation in all crystal orientations is greater than a first preset value;

[0079] Step S503: A second barrier sublayer is formed on the sidewalls and bottom of the trench and on the surface of the substrate; the second barrier sublayer includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein the first crystal orientation and the second crystal orientation are different.

[0080] like Figure 6 As shown in this embodiment of the present disclosure, in step S501, a substrate 100 is provided, and at least one trench 102 is formed in the substrate 100 (e.g., Figure 6 (As shown in the dashed box).

[0081] Here, the substrate can be a semiconductor substrate; specifically, it includes at least one elemental semiconductor material (e.g., silicon (Si) substrate, germanium (Ge) substrate, etc.), at least one III-V compound semiconductor material (e.g., gallium nitride (GaN) substrate, gallium arsenide (GaAs) substrate, indium phosphide (InP) substrate, etc.), at least one II-VI compound semiconductor material, at least one organic semiconductor material, or other semiconductor materials known in the art. It may also include other substrates containing semiconductor materials, such as silicon-on-insulator (SOI) substrates, germanium-on-insulator (GeOI) substrates, polycrystalline semiconductor layers on insulating layers, silicon-germanium substrates, etc. Alternatively, the substrate can be formed of a non-conductive material, such as glass, plastic, or sapphire wafers. This disclosure does not impose any special limitations on the material of the substrate.

[0082] In one specific example, the substrate material may include silicon dioxide.

[0083] like Figure 6 As shown in the present embodiment, in step S502, a first barrier sublayer 106 is formed on the sidewalls and bottom of the trench 102 and on the surface of the substrate 100; the first barrier sublayer 106 includes a barrier material in which the proportion of the first crystal orientation in all crystal orientations is greater than a first preset value.

[0084] Here, the first surface of the first barrier sublayer is in direct contact with the sidewalls and bottom of the trench and the substrate surface, and the second surface of the first barrier sublayer is in direct contact with the second barrier sublayer formed in subsequent processes. Considering the good step coverage (SC) of the first barrier sublayer in the first crystal orientation, a barrier material with a proportion greater than a first preset value in all crystal orientations is selected to form the first barrier sublayer.

[0085] Typically, it is difficult to form a film of uniform thickness in areas with breaks or unevenness on the substrate surface. Step coverage is an indicator used to measure the thickness loss of the film at the step when it crosses a step; that is, the ratio between the film thickness at the step and the film thickness at the flat area. Step coverage can be the ratio between the film thickness covering the trench sidewalls and the film thickness covering the substrate surface, or it can be the ratio between the film thickness covering the trench bottom and the film thickness covering the substrate surface. The closer the step coverage is to 1, the smaller the difference in film thickness between the step (i.e., the sidewalls and bottom of the trench) and the flat area (i.e., the substrate surface); the farther the step coverage is from 1, the thinner the film thickness at the step (i.e., the sidewalls and bottom of the trench) than the film thickness at the flat area (i.e., the substrate surface).

[0086] Here, the proportion of the first crystal orientation of the first barrier sublayer in all crystal orientations is greater than a first preset value. This embodiment does not impose any specific limitation on the value of the first preset value.

[0087] like Figure 6 As shown in this embodiment, in step S503, a second barrier sublayer 108 is formed on the sidewalls and bottom of the trench 102 and on the surface of the substrate 100 on the first barrier sublayer 106; the second barrier sublayer 108 includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein, the first barrier sublayer 106 and the second barrier sublayer 108 together form a barrier layer 104, and the first crystal orientation and the second crystal orientation are different.

[0088] Here, the first surface of the second barrier sublayer is in direct contact with the sidewalls and bottom of the trench and the first barrier sublayer on the substrate surface, and the second surface of the second barrier sublayer is in direct contact with the metal material layer formed in subsequent processes. It is precisely because the second barrier sublayer with the second crystal orientation is conducive to the nucleation of the metal material that a barrier material with a second crystal orientation in all crystal orientations is selected to form the second barrier sublayer.

[0089] Here, the second crystal orientation of the second barrier sublayer accounts for a greater proportion than a second preset value among all crystal orientations. This disclosure does not impose a specific limitation on the value of the second preset value; for example, the second preset value can be 70%.

[0090] In some embodiments, the first preset value and the second preset value may be the same or different.

[0091] In this embodiment, a first barrier sublayer with a first crystal orientation ratio greater than a first preset value is formed on the sidewalls, bottom, and substrate surface of the trench. A second barrier sublayer with a second crystal orientation ratio greater than a second preset value is formed on the first barrier sublayer on the sidewalls, bottom, and substrate surface of the trench. Taking advantage of the good step coverage of the first barrier sublayer with the first crystal orientation, the second barrier sublayer with the second crystal orientation is more conducive to the formation of a metal nucleation layer in subsequent processes. Forming first and second barrier sublayers with different crystal orientations can reduce the probability of voids or seams in the filling material of the trench, thereby improving the electrical performance of the semiconductor structure and thus improving the product yield.

[0092] In some embodiments, the materials of both the first barrier sublayer and the second barrier sublayer may include titanium nitride (TiN).

[0093] It should be noted that during the deposition of tungsten, some reactants may corrode the substrate. The formation of a first and second barrier sublayer can prevent the reactants from eroding the substrate during deposition. Furthermore, the formation of the first and second barrier sublayers can increase the adhesion between the metal material layer formed in subsequent processes and the substrate, thereby reducing the probability of the metal material peeling off from the substrate surface.

[0094] Here, by controlling the reaction parameters for forming the first and second barrier sublayers, first and second barrier sublayers with different crystal orientations can be achieved. For example, the ratio between the reactants forming the first and second barrier sublayers can be controlled to be different, thereby forming first and second barrier sublayers with different crystal orientations.

[0095] In one specific example, a first barrier sublayer and a second barrier sublayer are formed using processes including, but not limited to, CVD.

[0096] In this embodiment of the disclosure, step S502 includes: reacting the first reactant and the second reactant on the sidewalls and bottom of the trench 102 and on the surface of the substrate 100 to form a first barrier sublayer 106.

[0097] Step S503 includes: reacting a first reactant and a second reactant on the sidewalls and bottom of the trench 102 and on the surface of the substrate 100 to form a second barrier layer 108.

[0098] The ratio between the first reactant and the second reactant during the formation of the first barrier sublayer 106 is different from the ratio between the first reactant and the second reactant during the formation of the second barrier sublayer 108.

[0099] Here, by controlling the different ratios between the first and second reactants, first and second barrier sublayers with different crystal orientations can be formed. Utilizing the different properties of barrier materials with different crystal orientations, the first barrier sublayer, with a first crystal orientation proportion greater than a first preset value, exhibits good step coverage, while the second barrier sublayer, with a second crystal orientation proportion greater than a second preset value, is more conducive to the formation of a metal nucleation layer in subsequent processes. Therefore, by controlling the crystal structure of the first and second barrier sublayers, the step coverage of the barrier layer is improved, and the filling capacity of deposited tungsten metal in subsequent processes is enhanced.

[0100] In this embodiment of the disclosure, the first crystal orientation is (200) crystal orientation and the second crystal orientation is (111) crystal orientation.

[0101] refer to Figure 7A , Figure 7A This is a flowchart illustrating the formation of a first barrier sublayer, provided as an embodiment of the present disclosure. Figure 7A As shown in this embodiment, the material of the first barrier sublayer includes titanium nitride; step S502 includes:

[0102] A first barrier sublayer is formed by reacting a first reactant, ammonia, with a first gas flow rate F1 carried by a carrier gas (e.g., nitrogen) with a gas flow rate N1 and a second reactant, titanium tetrachloride, with a gas flow rate M1 carried by a carrier gas with a second gas flow rate E1, on the sidewalls and bottom of the trench and on the substrate surface; wherein the ratio between the first gas flow rate F1 and the second gas flow rate E1 is less than 30.

[0103] For example, the process of forming the first barrier sublayer may include the following steps: introducing nitrogen gas with a gas flow rate M1 carrying titanium tetrachloride with a second gas flow rate E1; purging the remaining gas with nitrogen gas; introducing nitrogen gas with a gas flow rate N1 carrying ammonia gas with a first gas flow rate F1; purging the remaining gas again with nitrogen gas; so that titanium tetrachloride and ammonia gas react to form the first barrier sublayer.

[0104] Here, by controlling the ratio between the first gas flow rate F1 and the second gas flow rate E1 to be less than 30, a first barrier sublayer can be formed in which the proportion of the first crystal orientation (200) in all crystal orientations is greater than a first preset value.

[0105] In some embodiments, the carrier gas may include an inert gas. Exemplarily, the carrier gas may include, but is not limited to, nitrogen.

[0106] refer to Figure 7B , Figure 7B This is a flowchart illustrating the formation of a second barrier sublayer, provided as an embodiment of the present disclosure. Figure 7B As shown in this embodiment, the material of the second barrier sublayer includes TiN; step S503 includes:

[0107] A second barrier layer is formed on the sidewalls and bottom of the trench and on the surface of the substrate by reacting ammonia with a third gas flow rate F2 carried by a carrier gas with a gas flow rate F2 and titanium tetrachloride with a fourth gas flow rate E2 carried by a carrier gas with a gas flow rate M2; wherein the ratio between the third gas flow rate F2 and the fourth gas flow rate E2 is greater than 30.

[0108] For example, the process of forming the second barrier sublayer may include the following steps: introducing nitrogen gas with a gas flow rate of M2 carrying titanium tetrachloride with a fourth gas flow rate of E2; purging the remaining gas with nitrogen gas; introducing nitrogen gas with a gas flow rate of N2 carrying ammonia gas with a third gas flow rate of F2; purging the remaining gas again with nitrogen gas; so that titanium tetrachloride and ammonia gas react to form the second barrier sublayer.

[0109] Here, by controlling the ratio between the third gas flow rate F2 and the fourth gas flow rate E2 to be greater than 30, a second barrier sublayer can be formed in which the proportion of the second crystal orientation (111) in all crystal orientations is greater than a second preset value.

[0110] It should be noted that titanium nitride includes (111) crystal orientation, (200) crystal orientation, (220) crystal orientation, and (222) crystal orientation. The first barrier sublayer may include the above four crystal orientations; or, may include the (200) crystal orientation and any two other crystal orientations; or, may include the (200) crystal orientation and any one other crystal orientation; or, may include the (200) crystal orientation. The second barrier sublayer may include the above four crystal orientations; or, may include the (111) crystal orientation and any two other crystal orientations; or, may include the (111) crystal orientation and any one other crystal orientation; or, may include the (111) crystal orientation.

[0111] In some embodiments, the first barrier sublayer may include a (200) crystal orientation, and at least one of a (111) crystal orientation, a (220) crystal orientation, and a (222) crystal orientation, wherein the proportion of the (200) crystal orientation among all crystal orientations is greater than a first preset value. In other embodiments, the first barrier sublayer may include only the (200) crystal orientation, thus the proportion of the (200) crystal orientation in the first barrier sublayer is 100%. In the embodiments of this disclosure, the first barrier sublayer includes the (200) crystal orientation, but there is no particular limitation on whether the first barrier sublayer includes other crystal orientations.

[0112] In some embodiments, the second barrier sublayer may include a (111) crystal orientation, and at least one of (200), (220), and (222) crystal orientations, wherein the proportion of the (111) crystal orientation among all crystal orientations is greater than a second preset value. In other embodiments, the second barrier sublayer may include only the (111) crystal orientation, thus the proportion of the (111) crystal orientation in the second barrier sublayer is 100%. In the embodiments of this disclosure, the second barrier sublayer includes the (111) crystal orientation, but there is no particular limitation on whether the second barrier sublayer includes other crystal orientations.

[0113] In this embodiment of the disclosure, the formation of the first barrier sublayer has a first reaction time, the formation of the second barrier sublayer has a second reaction time, and the ratio between the first reaction time and the second reaction time is greater than 10.

[0114] Here, the process of forming the first barrier sublayer is called the X cycle, and the process of forming the second barrier sublayer is called the Y cycle. The ratio between the duration of the X cycle and the duration of the Y cycle is greater than 10. Of course, the reaction time can characterize the thickness of the first and second barrier sublayers to some extent, with the first barrier sublayer serving as the main layer in the barrier layer.

[0115] In this embodiment of the present disclosure, the first barrier sublayer and the second barrier sublayer together form a barrier layer, and the thickness of the barrier layer is 2nm to 20nm.

[0116] Here, the thickness of the barrier layer refers to the sum of the thicknesses of the first barrier sublayer and the second barrier sublayer. For a barrier layer covering the bottom of the trench and the surface of the substrate, the thickness of the barrier layer refers to the dimension of the barrier layer along the thickness direction of the substrate. For a barrier layer covering the sidewalls of the trench, the thickness of the barrier layer refers to the dimension of the barrier layer along the direction perpendicular to the thickness of the substrate.

[0117] refer to Figure 8 , Figure 8 X-ray diffraction patterns of titanium nitride formed under different ammonia gas flow rates. Figure 8 The X-ray diffraction pattern is shown with the horizontal axis representing 2θ, in degrees (°); and the vertical axis representing intensity. Figure 8 The X-ray diffraction curves of titanium nitride formed under four different ammonia gas flow rates are shown, where ammonia flow rate G1 < ammonia flow rate G2 < ammonia flow rate G3 < ammonia flow rate G4. At ammonia flow rate G1, titanium nitride with the (200) crystal orientation is more easily formed; at ammonia flow rate G4, titanium nitride with the (111) crystal orientation is more easily formed. In other words, the higher the ammonia flow rate, the easier it is to form titanium nitride with the (111) crystal orientation; the higher the titanium tetrachloride flow rate, the easier it is to form titanium nitride with the (200) crystal orientation.

[0118] Here, during the formation of the first barrier sublayer, the ratio between the ammonia flow rate and the titanium tetrachloride flow rate is less than 30, and the proportion of the (200) crystal orientation of the first barrier sublayer in all crystal orientations is greater than the first preset value; during the formation of the second barrier sublayer, the ratio between the ammonia flow rate and the titanium tetrachloride flow rate is greater than 30, and the proportion of the (111) crystal orientation of the second barrier sublayer in all crystal orientations is greater than the second preset value.

[0119] refer to Figure 9 , Figure 9 X-ray diffraction patterns of titanium nitride with different crystal orientations. Figure 9 Figure (a) illustrates the (200) crystal orientation of titanium nitride; Figure 9 Figure (b) shows the (111) crystal orientation of titanium nitride.

[0120] refer to Figure 10 , Figure 10 Electron micrographs of titanium nitride with different crystal orientations. Figure 10 Figure (a) shows Figure 9 The electron microscope image of titanium nitride with the (200) crystal orientation in Figure (a) is shown. Figure 10 Figure (b) shows Figure 9 Electron microscopy image of titanium nitride with the (111) crystal orientation in Figure (b). Figure 10 As shown in Figure (a), the (200) crystal orientation of titanium nitride exhibits good step coverage, which is beneficial for improving the filling capacity of deposited tungsten metal in subsequent processes, avoiding voids or seams in the metal material layer within the trench, thereby improving the electrical performance of the semiconductor structure and increasing product yield. Figure 10 As shown in Figure (b), the step coverage of titanium nitride with (111) crystal orientation is poor. Forming titanium nitride with (111) crystal orientation directly on the sidewalls and bottom of the trench and on the substrate surface is not conducive to the deposition of tungsten metal in subsequent processes.

[0121] refer to Figure 11 , Figure 11 The graph shows the relationship between the step coverage of titanium nitride and the gas flow rate of titanium tetrachloride. Figure 11 The x-axis represents the gas flow rate of titanium tetrachloride, in standard cubic centimeter per minute (sccm); the y-axis represents the step coverage of titanium nitride. Figure 11 This indicates that as the gas flow rate of titanium tetrachloride increases, the step coverage of titanium nitride formation also increases.

[0122] In this embodiment, taking advantage of the different properties of titanium nitride with different crystal orientations, titanium nitride with a (200) crystal orientation ratio greater than a first preset value is first formed on the sidewalls and bottom of the trench and on the substrate surface. The (200) crystal orientation titanium nitride has a better step coverage (e.g., Figure 10(as shown in Figure (a)); then form titanium nitride with a (111) crystal orientation ratio greater than the second preset value. Titanium nitride with a (111) crystal orientation is more conducive to nucleation, which is conducive to the formation of a metal nucleation layer and avoids the appearance of holes or seams in the metal material layer.

[0123] In this embodiment of the disclosure, after step S503, the manufacturing method further includes:

[0124] A metal material layer 110 is formed on the sidewalls and bottom of the trench 102 and on the second barrier layer 108 on the surface of the substrate 100.

[0125] refer to Figure 12 , Figure 12 This is a cross-sectional structural diagram illustrating the process of forming a metallic material layer according to an embodiment of this disclosure. Figure 12 As shown in Figure (a), an active atom layer 112 is formed on the second barrier layer 108 using a third reactant. The third reactant may include, but is not limited to, diborane. Diborane is used to wet the substrate, causing it to decompose on the substrate surface. More specifically, it decomposes on the surface of the second barrier layer, allowing as many boron atoms as possible to remain on the surface of the second barrier layer, thus forming an active boron atom layer.

[0126] refer to Figure 13A and Figure 13B , Figure 13A This is a schematic diagram of the decomposition of diborane on the surface of titanium nitride with the (111) crystal orientation. Figure 13B The activation energy (E) for the decomposition of diborane on the surface of titanium nitride with the (111) crystal orientation. a ) and reaction energy (E) rxn The decomposition process of diborane on the surface of titanium nitride with a (111) crystal orientation may include the following steps: in step S1, the BB chemical bond and the BH chemical bond are decomposed, the activation energy of the decomposition reaction is 0.39 eV, and the reaction energy is -7.14 eV (i.e., the decomposition reaction releases energy); in step S2, the BH chemical bond is decomposed, and the reaction energy is -9.13 eV; in step S3, the BH chemical bond is decomposed, the activation energy of the decomposition reaction is 0.14 eV, and the reaction energy is -2.70 eV.

[0127] refer to Figure 13C and Figure 13D , Figure 13C This is a schematic diagram showing the decomposition of diborane on the surface of titanium nitride in other crystal orientations. Figure 13D The activation energy (E) for the surface decomposition of diborane on titanium nitride in other crystal orientations. a ) and reaction energy (E) rxnThe decomposition process of diborane on the surface of titanium nitride in other crystal orientations may include the following steps: In step S1, the BB chemical bond is broken, the activation energy of the decomposition reaction is 1.11 eV, and the reaction energy is -1.89 eV (i.e., the decomposition reaction releases energy); In step S2, the BH chemical bond is broken, the activation energy of the decomposition reaction is 1.65 eV, and the reaction energy is 1.29 eV (i.e., the decomposition reaction absorbs energy); In step S3, the BH chemical bond is broken, the activation energy of the decomposition reaction is 1.75 eV, and the reaction energy is 1.45 eV; In step S4, the BH chemical bond is broken, the activation energy of the decomposition reaction is 1.83 eV, and the reaction energy is 1.51 eV.

[0128] Combination Figures 13A to 13D The activation energy for the decomposition of diborane on the titanium nitride surface with the (111) crystal orientation is lower, the thermodynamic reaction proceeds spontaneously, and diborane is more easily decomposed.

[0129] In some embodiments, the thickness of the active atom layer is 0.1 nm to 5 nm.

[0130] like Figure 12 As shown in Figure (b), a metal nucleation layer 114 is formed on the second barrier sublayer 108 by reacting a fourth reactant with the active atom layer 112. The fourth reactant may include, but is not limited to, tungsten hexafluoride. During the reaction between tungsten hexafluoride and boron atoms, boron atoms are used to displace tungsten from the tungsten hexafluoride to form a tungsten nucleation layer on the surface of the second barrier sublayer.

[0131] In some embodiments, the thickness of the metal nucleation layer is 2 nm to 10 nm.

[0132] refer to Figure 14 , Figure 14 This is a schematic diagram illustrating the principle of forming a metal nucleation layer according to an embodiment of this disclosure. Figure 14 As shown in Figure (a), when the substrate is wetted with diborane, the diborane can decompose to form a boron atom layer on the trench sidewalls and bottom, as well as on the surface of the second barrier sublayer on the substrate surface; as shown in Figure (a), the substrate is wetted with diborane. Figure 14 As shown in Figures (b) and (c), tungsten hexafluoride can react with boron atomic layers to form tungsten nucleation layers.

[0133] In this embodiment, on the surface of the second barrier layer where the (111) crystal orientation ratio is greater than a second preset value, diborane is more easily decomposed into active boron atoms to form a boron atom layer. Thus, the more boron atoms on the surface of the second barrier layer where the (111) crystal orientation ratio is greater than the second preset value, the easier it is for them to react with tungsten hexafluoride to form a tungsten nucleation layer with better step coverage, thereby making it easier to form a tungsten body layer. This can improve the step coverage of the metal material layer, reduce the probability of voids or seams appearing in the metal material layer within the trench, thereby improving the electrical performance of the semiconductor structure and ultimately increasing the product yield. Furthermore, on the surface of the second barrier layer where the (111) crystal orientation ratio is greater than the second preset value, diborane can decompose into active boron atoms more quickly, which can also save time on substrate wetting.

[0134] like Figure 12 As shown in Figure (c), a metal bulk layer 116 is formed on the metal nucleation layer 114 by reacting a fourth reactant and a fifth reactant. The fifth reactant may include, but is not limited to, hydrogen gas. Hydrogen gas is reacted with tungsten hexafluoride to form a tungsten bulk layer on the basis of the tungsten nucleation layer.

[0135] In some embodiments, the thickness of the metal body layer is 20 nm to 100 nm.

[0136] It should be noted that wetting the substrate with diborane can form an active atom layer on the surface of the second barrier layer; after reacting with tungsten hexafluoride and the active atom layer, a tungsten nucleation layer is formed on the surface of the second barrier layer. At this point, the active atom layer has already participated in the chemical reaction, reacting with tungsten hexafluoride to form the tungsten nucleation layer. In other words, a tungsten nucleation layer is formed on the surface of the second barrier layer, but there is no separate active atom layer on the surface of the second barrier layer. Furthermore, by reacting hydrogen with tungsten hexafluoride, a tungsten bulk layer is formed on the basis of the tungsten nucleation layer. There is no clear boundary between the tungsten nucleation layer and the tungsten bulk layer, and there is no essential difference between the two.

[0137] For ease of explanation, Figure 12 The diagram illustrates the active atom layer 112, the metal nucleation layer 114, and the metal bulk layer 116, distinguishing the different layer structures with different filling patterns. In reality, the active atom layer reacts with tungsten hexafluoride, participating in the chemical reaction; therefore, there is no separate active atom layer on the surface of the second barrier layer. Furthermore, the metal nucleation layer and the metal bulk layer together form a metal material layer without a clear boundary. In other words, in the final semiconductor structure, a metal material layer is formed on the sidewalls and bottom of the trench and on the barrier layer on the substrate surface. Within this metal material layer, there are no separate active atom layers, metal nucleation layers, and metal bulk layers.

[0138] In this embodiment of the present disclosure, by controlling the crystal structure of the first barrier sublayer and the second barrier sublayer, the nucleation of the metal nucleation layer is promoted, the filling ability of the deposition process is improved, and the probability of holes or seams appearing in the metal material layer in the trench is reduced.

[0139] refer to Figure 15 , Figure 15 This is a cross-sectional schematic diagram of a semiconductor structure provided in an embodiment of this disclosure.

[0140] like Figure 15 As shown, this disclosure provides a semiconductor structure, which includes:

[0141] Substrate 100, in which at least one trench 102 is formed;

[0142] The first barrier sublayer 106 covers the sidewalls and bottom of the trench 102 and the surface of the substrate 100; the first barrier sublayer 106 includes a barrier material in which the proportion of the first crystal orientation in all crystal orientations is greater than a first preset value.

[0143] The second barrier sublayer 108 covers the sidewalls and bottom of the trench 102 and the surface of the substrate 100 of the first barrier sublayer 106; the second barrier sublayer 108 includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein the first crystal orientation and the second crystal orientation are different.

[0144] Metal material layer 110 covers the second barrier sub-layer 108 and fills the trench 102.

[0145] In this embodiment, the sidewalls and bottom of the trench and the substrate surface are covered with a first barrier sublayer. The first barrier sublayer includes a barrier material whose proportion of the first crystal orientation in all crystal orientations is greater than a first preset value, and the first barrier sublayer of the first crystal orientation has good step coverage. The first barrier sublayer of the trench sidewalls and bottom and the substrate surface is covered with a second barrier sublayer. The second barrier sublayer includes a barrier material whose proportion of the second crystal orientation in all crystal orientations is greater than a second preset value, and the second barrier sublayer of the second crystal orientation is more conducive to the formation of a metal nucleation layer in subsequent processes. In this way, by utilizing the different characteristics of the first and second crystal orientations of the barrier material, the probability of holes or seams appearing in the metal material layer in the trench is reduced, thereby improving the electrical performance of the semiconductor structure and thus improving the product yield.

[0146] In this embodiment of the present disclosure, the first barrier sublayer 106 and the second barrier sublayer 108 together form a barrier layer 104, and the thickness of the barrier layer 104 is 2nm to 20nm.

[0147] Here, the first barrier sublayer 106 and the second barrier sublayer 108 can together form the barrier layer 104.

[0148] In this embodiment of the disclosure, the materials of the first barrier sublayer and the second barrier sublayer both include TiN; the first crystal orientation is (200) crystal orientation, and the second crystal orientation is (111) crystal orientation.

[0149] In this embodiment of the disclosure, the material of the metal material layer 110 includes tungsten.

[0150] This disclosure provides a semiconductor structure and its manufacturing method. In this embodiment, a first barrier layer with a first crystal orientation ratio greater than a first preset value is first formed on the sidewalls and bottom of the trench and on the substrate surface. Then, a second barrier layer with a second crystal orientation ratio greater than a second preset value is formed. Utilizing the good step coverage of the first barrier layer with the first crystal orientation, and the fact that the second barrier layer with the second crystal orientation is more conducive to the formation of a metal nucleation layer in subsequent processes, forming first and second barrier layers with different crystal orientations can reduce the probability of voids or seams appearing in the trench filling material, thereby improving the electrical performance of the semiconductor structure and ultimately increasing product yield.

[0151] It should be understood that the phrase "an embodiment" or "one embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this disclosure. Therefore, "in one embodiment" or "one embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this disclosure, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this disclosure. The sequence numbers of the above-described embodiments are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0152] The above description is merely a preferred embodiment of this disclosure and does not limit the patent scope of this disclosure. Any equivalent structural transformations made using the contents of this specification and drawings under the inventive concept of this disclosure, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this disclosure.

Claims

1. A method for manufacturing a semiconductor structure, characterized in that, The manufacturing method includes: A substrate is provided in which at least one trench is formed; A first barrier sublayer is formed by reacting ammonia (NH3) with a first gas flow rate and titanium tetrachloride (TiCl4) with a second gas flow rate on the sidewalls and bottom of the trench and on the surface of the substrate. The first barrier sublayer includes a barrier material in which the proportion of a first crystal orientation in all crystal orientations is greater than a first preset value. The formation of the first barrier sublayer has a first reaction time. The first crystal orientation is (200) crystal orientation. The ratio between the first gas flow rate and the second gas flow rate is less than 30. A second barrier sublayer is formed by reacting a first reactant NH3 with a third gas flow rate and a second reactant TiCl4 with a fourth gas flow rate on the sidewalls and bottom of the trench and on the surface of the substrate. The second barrier sublayer includes a barrier material in which the proportion of a second crystal orientation in all crystal orientations is greater than a second preset value. The formation of the second barrier sublayer has a second reaction time, the ratio between the first reaction time and the second reaction time is greater than 10, the second crystal orientation is (111) crystal orientation, and the ratio between the third gas flow rate and the fourth gas flow rate is greater than 30.

2. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, The first barrier sublayer and the second barrier sublayer together form a barrier layer, the thickness of which is 2nm to 20nm.

3. The method for manufacturing a semiconductor structure according to claim 1, characterized in that, After forming a second barrier sublayer on the sidewalls and bottom of the trench and on the surface of the substrate, the manufacturing method further includes: A metallic material layer is formed on the sidewalls and bottom of the trench and on the second barrier layer on the surface of the substrate.

4. The method for manufacturing a semiconductor structure according to claim 3, characterized in that, The formation of a metallic material layer on the sidewalls and bottom of the trench and on the second barrier sublayer of the substrate surface includes: A layer of active atoms is formed on the second barrier sublayer using a third reactant; The fourth reactant reacts with the active atom layer to form a metal nucleation layer on the second barrier sublayer; The fourth and fifth reactants are used to react and form a metal bulk layer on the metal nucleation layer.

5. The method for manufacturing a semiconductor structure according to claim 4, characterized in that, The third reactant includes diborane (B₂H₆), and the active atomic layer includes a boron atom layer; and / or, The fourth reactant includes tungsten hexafluoride (WF6); and / or, The fifth reactant includes hydrogen gas (H2).

6. A semiconductor structure, characterized in that, The semiconductor structure includes: A substrate having at least one trench formed therein; A first barrier sublayer covers the sidewalls and bottom of the trench and the surface of the substrate; the first barrier sublayer includes a barrier material in which the proportion of a first crystal orientation in all crystal orientations is greater than a first preset value, and the first crystal orientation is the (200) crystal orientation; The second barrier sublayer covers the sidewalls and bottom of the trench and the surface of the substrate of the first barrier sublayer; the second barrier sublayer includes a barrier material in which the proportion of the second crystal orientation in all crystal orientations is greater than a second preset value; wherein the first crystal orientation and the second crystal orientation are different, and the second crystal orientation is (111) crystal orientation; the ratio between the thickness of the first barrier sublayer and the thickness of the second barrier sublayer is greater than 10. A metal material layer that covers the second barrier sublayer and fills the trench.

7. The semiconductor structure according to claim 6, characterized in that, The first barrier sublayer and the second barrier sublayer together form a barrier layer, the thickness of which is 2nm to 20nm.

8. The semiconductor structure according to claim 6, characterized in that, Both the first and second barrier sublayers are made of TiN.

9. The semiconductor structure according to claim 6, characterized in that, The material of the metallic material layer includes tungsten (W).

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