Semiconductor structure and method of forming the same

Abstract

Embodiments of the present disclosure provide a semiconductor structure and a forming method thereof. The method comprises: providing a substrate, the substrate is formed with an insulating layer, an initial metal conductive layer, an initial sacrificial layer and a mask layer which are sequentially stacked, the initial sacrificial layer comprises a metal oxide layer; based on the patterned mask layer, performing etching treatment on the initial sacrificial layer and the initial metal conductive layer by using an oxygen source gas as an etching gas, to form a metal conductive layer and a sacrificial layer on the metal conductive layer; performing ashing treatment by using the oxygen source gas as the etching gas, to remove the patterned mask layer; performing etching treatment by using an alkaline etching liquid, to remove the sacrificial layer and by-products formed in the etching treatment and the ashing treatment, and to expose the metal conductive layer; and forming an isolation structure between adjacent metal conductive layers.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor technology, and relates to but is not limited to a semiconductor structure and a forming method thereof. BACKGROUND

[0002] In a semiconductor device, it is required to form a landing pad (LP) between a memory region transistor and a capacitor structure and to form a metal conductive layer in a peripheral region. However, when the metal conductive layer is formed, the metal conductive layer is prone to residual by-products in a process, which is prone to cause short circuit between adjacent metal conductive layers. Therefore, it is required to provide a new process forming method of the metal conductive layer to reduce the short circuit between adjacent metal conductive layers. SUMMARY

[0003] Therefore, the present disclosure provides a semiconductor structure and a forming method thereof.

[0004] In a first aspect, the present disclosure provides a forming method of a semiconductor structure, the method comprising: providing a substrate, the substrate being formed with an insulating layer, an initial metal conductive layer, an initial sacrificial layer and a mask layer which are sequentially stacked, the initial sacrificial layer comprising a metal oxide layer; based on a patterned mask layer, performing etching treatment on the initial sacrificial layer and the initial metal conductive layer by using an oxygen source gas as an etching gas, to form a metal conductive layer and a sacrificial layer on the metal conductive layer; performing ashing treatment by using the oxygen source gas as an etching gas, to remove the patterned mask layer; performing etching treatment by using an alkaline etching liquid, to remove the sacrificial layer and by-products formed in the etching treatment and the ashing treatment, and to expose the metal conductive layer; and forming an isolation structure between adjacent metal conductive layers.

[0005] In some embodiments, the forming method of the initial sacrificial layer comprises: performing planarization treatment on the initial metal conductive layer; and performing oxidation treatment on the initial metal conductive layer by using oxygen plasma, to form the initial sacrificial layer on a surface of the initial metal conductive layer; wherein the material of the initial metal conductive layer and the metal conductive layer comprises tungsten, and the material of the initial sacrificial layer comprises tungsten oxide.

[0006] In some embodiments, the mask layer includes an amorphous carbon layer; based on the patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form a metal conductive layer and a sacrificial layer located on the metal conductive layer, including: forming a patterned amorphous carbon layer on the initial sacrificial layer; and based on the patterned amorphous carbon layer, using an in-situ oxygen plasma etching process to etch the initial sacrificial layer and the initial metal conductive layer to form the metal conductive layer and the sacrificial layer located on the metal conductive layer.

[0007] In some embodiments, using an oxygen source gas as an etching gas for ashing to remove the patterned mask layer includes: using oxygen plasma for ashing to remove the patterned amorphous carbon layer.

[0008] In some embodiments, the byproducts formed during the etching and ashing processes include tungsten oxide.

[0009] In some embodiments, an alkaline etchant is used to etch the sacrificial layer and the byproducts formed during the etching and ashing processes, and to expose the conductive metal layer. This includes: pretreating the surface of the sacrificial layer to remove native oxides and expose the sacrificial layer and the byproducts formed during the etching and ashing processes; removing the sacrificial layer and the byproducts formed during the etching and ashing processes using an alkaline etchant to expose the conductive metal layer; cleaning the surface of the conductive metal layer of any remaining alkaline etchant; and drying the conductive metal layer.

[0010] In some embodiments, the alkaline corrosive solution comprises a mixture of ammonia and deionized water, wherein the volume ratio of ammonia to deionized water in the mixture ranges from 5:1 to 1000:1.

[0011] In some embodiments, isopropanol and nitrogen are used to dry the metal conductive layer.

[0012] In some embodiments, forming an isolation structure between adjacent conductive metal layers includes: sequentially forming a first dielectric layer and a second dielectric layer between adjacent conductive metal layers to form the isolation structure.

[0013] In some embodiments, an initial barrier layer is further formed on the substrate between the insulating layer and the initial conductive metal layer; based on a patterned mask layer, an oxygen source gas is used as an etching gas to etch the initial sacrificial layer and the initial conductive metal layer to form a conductive metal layer and a sacrificial layer on the conductive metal layer, including: based on a patterned mask layer, an oxygen source gas is used as an etching gas to etch the initial sacrificial layer, the initial conductive metal layer, and the initial barrier layer to form a trench, and a barrier layer, the conductive metal layer, and the sacrificial layer are formed sequentially stacked on both sides of the trench; an isolation structure is formed between adjacent conductive metal layers, including: forming the isolation structure in the trench.

[0014] In some embodiments, the processing gas used in the process of forming the initial sacrificial layer on the surface of the initial metallic conductive layer includes: oxygen, a hydrogen-nitrogen mixture, nitrogen, and argon; the flow rate of the processing gas ranges from 100 to 15,000 standard milliliters per minute; the pressure of the oxygen plasma generation region ranges from 10 to 10,000 millitors; and the radio frequency power ranges from 10 to 10,000 watts.

[0015] In a second aspect, embodiments of this disclosure provide a semiconductor structure formed using the method of the first aspect, comprising: a substrate on which an insulating layer is formed; a metal conductive layer located on the insulating layer; and an isolation structure located between adjacent metal conductive layers.

[0016] In some embodiments, the material of the metal conductive layer includes tungsten.

[0017] In some embodiments, the isolation structure includes: a first dielectric layer located on both sides of the metal conductive layer and a second dielectric layer in contact with the first dielectric layer; wherein the first dielectric layer and the second dielectric layer fill the gap between adjacent metal conductive layers.

[0018] In some embodiments, the structure further includes a barrier layer located between the insulating layer and the metal conductive layer.

[0019] In this embodiment, firstly, an insulating layer, an initial conductive metal layer, an initial sacrificial layer, and a mask layer are sequentially stacked on a substrate. The initial sacrificial layer protects the initial conductive metal layer from damage during the subsequent removal of the patterned mask layer. Secondly, based on the patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial conductive metal layer. This yields the desired patterned conductive metal layer and the sacrificial layer located on the conductive metal layer, and ensures that the byproducts formed during the etching process mainly consist of metal oxides. Thirdly, during the ashing process of removing the patterned mask layer using an oxygen source gas as the etching gas, the oxygen source gas will... The first step involves ensuring that the byproducts formed during the ashing process mainly consist of metal oxides. Secondly, an alkaline etching solution is used to remove the sacrificial layer and the byproducts formed during the etching and ashing processes. The alkaline etching solution reacts with the sacrificial layer and byproducts but not with the conductive metal layer, thus reducing damage to the conductive metal layer. Furthermore, since the byproducts formed during etching and ashing, as well as the sacrificial layer, are all metal oxides, a single solution can be used to etch and remove both the sacrificial layer and byproducts in one step, simplifying the process. Finally, an isolation structure is formed between adjacent conductive metal layers, further reducing the possibility of short circuits between them. Attached Figure Description

[0020] In the accompanying drawings (which are not necessarily drawn to scale), similar reference numerals may describe similar parts in different views. Similar reference numerals with different letter suffixes may indicate different examples of similar parts. The drawings illustrate, by way of example and not limitation, the various embodiments discussed herein.

[0021] Figure 1 A schematic diagram illustrating the implementation process of a method for forming a semiconductor structure according to an embodiment of this disclosure;

[0022] Figures 2a to 2e A schematic diagram of the composition structure of a semiconductor structure formation process provided in an embodiment of this disclosure;

[0023] Figure 3a and Figure 3b These are schematic diagrams illustrating the composition and structure of a semiconductor structure formation process provided in the embodiments of this disclosure;

[0024] Figures 3c to 3e This disclosure provides a schematic diagram of forming an initial sacrificial layer on the surface of an initial metallic conductive layer;

[0025] Figure 4 A schematic diagram of the composition structure of a semiconductor structure formation process provided in an embodiment of this disclosure;

[0026] Figure 5aA schematic diagram illustrating the implementation flow of another method for forming a semiconductor structure provided in this embodiment of the disclosure;

[0027] Figures 5b to 5h This is a schematic diagram illustrating the composition of a semiconductor structure formation process provided in an embodiment of the present disclosure. Detailed Implementation

[0028] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] This disclosure provides a method for forming a semiconductor structure, with reference to... Figure 1 The method includes steps S101 to S105, wherein:

[0034] Step S101: A substrate is provided, on which an insulating layer, an initial metal conductive layer, an initial sacrificial layer and a mask layer are formed in sequence, wherein the initial sacrificial layer includes a metal oxide layer.

[0035] The substrate can be a silicon substrate, a silicon-on-insulator substrate, etc. The substrate may also include other semiconductor elements or semiconductor compounds, such as silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), or indium antimonide (InSb), or other semiconductor alloys, such as gallium arsenide phosphide (GaAsP), aluminum indium arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GaInAs), gallium indium phosphide (GaInP), and / or gallium indium arsenide phosphide (GaInAsP) or combinations thereof.

[0036] The insulating layer can be made of one or more of the following materials: silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide oxide, borosilicate glass, phosphosilicate glass, and borosilicate phosphosilicate glass. The insulating layer can be formed using processes such as chemical vapor deposition, physical vapor deposition, and atomic layer deposition.

[0037] The initial metal conductive layer can be made of at least one of the following materials: tungsten (W), tantalum (Ta), or titanium (Ti).

[0038] The initial sacrificial layer serves to protect the initial conductive metal layer from damage during subsequent processes. The initial sacrificial layer may include a metal oxide layer, and the metal contained in the initial sacrificial layer can be the same as the metal contained in the initial conductive metal layer. For example, both may contain tungsten, meaning the initial conductive metal layer is an initial tungsten layer and the initial sacrificial layer is a tungsten oxide layer. Alternatively, the metal contained in the initial sacrificial layer may be different from the metal contained in the initial conductive metal layer; for example, the initial conductive metal layer may be an initial tungsten layer and the initial sacrificial layer is a tantalum oxide layer. This disclosure uses a commonly used material in conductive metal layers, such as tungsten, as an example, specifically assuming that both the initial sacrificial layer and the initial conductive metal layer contain tungsten.

[0039] Specific portions of the mask layer can be transformed into a patterned mask layer in subsequent processes. The mask layer can be a double-layer or even multi-layer structure, or a single-layer structure; in a double-layer or multi-layer structure, the upper mask layer protects the lower mask layer, reducing damage to the lower mask layer and thus reducing defects in the patterned mask layer, thereby improving the pattern transfer effect. The mask layer can be made of one or more of silicon oxide, silicon nitride, silicon carbide, silicon oxynitride, amorphous carbon, polycrystalline silicon, hafnium oxide, titanium oxide, zirconium oxide, titanium nitride, and tantalum nitride, and can be formed by any of the following processes: chemical vapor deposition, physical vapor deposition, atomic layer deposition, spin coating, or any other suitable process. This disclosure does not limit the type or number of mask layers.

[0040] In some embodiments, a photoresist layer and an anti-reflective layer may also be formed on the mask layer. In practice, the photoresist layer can be exposed, developed, and washed. The portion of the photoresist layer retained is used to etch the anti-reflective layer and the mask layer, preserving the portion protected by the photoresist, thus forming a patterned mask layer. This improves the accuracy of the pattern formation in the mask layer, thereby increasing the yield of semiconductor devices.

[0041] Step S102: Based on the patterned mask layer, oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form the metal conductive layer and the sacrificial layer located on the metal conductive layer.

[0042] Here, the oxygen source gas can include oxygen and / or ozone, etc. In practice, the oxygen source gas can be excited under radio frequency power to generate ionization and form plasma. Under the impact of electrons, the gas in the reaction chamber not only transforms into ions but also absorbs energy and forms a large number of reactive functional groups. These reactive functional groups react chemically with the surface of the etched material (including the initial sacrificial layer and the initial conductive metal layer) to form volatile reaction products. These reaction products then detach from the surface of the etched material and are extracted from the reaction chamber by a vacuum system.

[0043] Step S103: Use oxygen source gas as etching gas for ashing treatment to remove the patterned mask layer.

[0044] The oxygen source gas can include oxygen and / or ozone. Ashing refers to the removal of residual photoresist, patterned mask layers, or other organic matter.

[0045] It should be noted that if a non-oxygen source gas, such as a nitrogen source gas, is used during the ashing process, the nitrogen source gas will react with the metal conductive layer to form a byproduct, metal nitride, such as tungsten nitride. The byproducts generated during etching mainly include metal oxides, which differ from those generated during ashing. If a single solution is used to remove these byproducts from both etching and ashing processes simultaneously, it may be insufficient to remove both metal oxides and metal nitrides. This reduces the effectiveness of byproduct removal, resulting in some byproducts remaining on the metal conductive layer. These residual byproducts may migrate between adjacent metal conductive layers during subsequent cleaning, causing short circuits and reducing the yield of the semiconductor structure. Therefore, a nitrogen-free gas, such as an oxygen source gas, should be used during ashing. This ensures that the byproducts generated during etching and ashing are the same, allowing for the removal of both byproducts in a single solution. This simplifies the process and improves the yield of the semiconductor structure.

[0046] Step S104 involves using an alkaline etching solution to perform etching treatment to remove the sacrificial layer and byproducts formed during the etching and ashing processes, and to expose the conductive metal layer.

[0047] The alkaline corrosive solution may contain a base having a pKb of less than or equal to about 5, less than or equal to about 4.8, less than or equal to about 4.75, less than or equal to about 4.7, less than or equal to about 4.5, less than or equal to about 3, less than or equal to about 2, or less than or equal to about 1. In some embodiments, the base may include an organic base (e.g., pyridine, methylamine, imidazole, hydroxides of organic cations). In some embodiments, the base may include a basic salt (e.g., sodium carbonate, sodium acetate, compounds having a weak acid component that hydrolyzes to form an alkaline solution). In some embodiments, the base may include an alkali metal. In some embodiments, the base may include hydroxide ions. In some embodiments, the base may include one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), or ammonium hydroxide (NH4OH).

[0048] The alkaline etching solution in this embodiment may include an ammonia-deionized water mixture (ADM), wherein the volume ratio of ammonia to deionized water in the ADM ranges from 5:1 to 1000:1. ADM can react with the sacrificial layer as shown in formula (1), wherein the tungsten oxide W in the sacrificial layer... x O y It reacts with ammonium hydroxide to form ammonium tungstate, which is soluble in water, thus removing the sacrificial layer; at the same time, ADM does not react with the metal conductive layer, thus reducing damage to the metal conductive layer.

[0049] W x O y +NH4OH→(NH4)6W7O 24 ·6H2O formula (1)

[0050] Byproducts formed during etching and ashing processes may include tungsten oxide (W). x O y In this case, x can be equal to 1 and y can be equal to 3, and tungsten oxide is tungsten trioxide.

[0051] Step S105: An isolation structure is formed between adjacent conductive metal layers.

[0052] The isolation structure is used to isolate adjacent metal conductive layers, further reducing the possibility of short circuits between adjacent metal conductive layers.

[0053] In this embodiment, firstly, an insulating layer, an initial conductive metal layer, an initial sacrificial layer, and a mask layer are sequentially stacked on a substrate. The initial sacrificial layer protects the initial conductive metal layer from damage during the subsequent removal of the patterned mask layer. Secondly, based on the patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial conductive metal layer. This yields the desired patterned conductive metal layer and the sacrificial layer located on the conductive metal layer, and ensures that the byproducts formed during the etching process mainly consist of metal oxides. Thirdly, during the ashing process of removing the patterned mask layer using an oxygen source gas as the etching gas, the oxygen source gas will... The first step involves ensuring that the byproducts formed during the ashing process mainly consist of metal oxides. Secondly, an alkaline etching solution is used to remove the sacrificial layer and the byproducts formed during the etching and ashing processes. The alkaline etching solution reacts with the sacrificial layer and byproducts but not with the conductive metal layer, thus reducing damage to the conductive metal layer. Furthermore, since the byproducts formed during etching and ashing, as well as the sacrificial layer, are all metal oxides, a single solution can be used to etch and remove both the sacrificial layer and byproducts in one step, simplifying the process. Finally, an isolation structure is formed between adjacent conductive metal layers, further reducing the possibility of short circuits between them.

[0054] The following is combined with Figures 2a to 2e Steps S101 to S105 will be further explained.

[0055] refer to Figure 2a An insulating layer 202, an initial metal conductive layer 203a, an initial sacrificial layer 204a and a mask layer 205a are formed on a substrate 201 in sequence. The initial sacrificial layer 204a includes a metal oxide layer.

[0056] refer to Figure 2b A patterned mask layer 205 is formed on the initial sacrificial layer 204a. It can be seen that the patterned mask layer 205 exposes part of the initial sacrificial layer 204a and defines the position for subsequent etching.

[0057] Also refer to Figure 2b and Figure 2c Based on the patterned mask layer 205, oxygen source gas is used as the etching gas to etch the initial sacrificial layer 204a and the initial metal conductive layer 203a to form the metal conductive layer 203 and the sacrificial layer 204 located on the metal conductive layer 203. Since part of the patterned mask layer 205 is consumed during the etching process, it can be observed that… Figure 2c The patterned mask layer in the middle is 205 times Figure 2b The patterned mask layer 205 is short. During implementation, refer to... Figure 2cDuring the etching process, the etched initial metal conductive layer 203b is redeposited onto the upper surface and sidewalls of the patterned mask layer 205. Some of the initial metal conductive layer 203b is oxidized into metal oxides (e.g., tungsten oxide) and becomes a byproduct formed during the etching process. The initial metal conductive layer 203b that is not oxidized during the etching process will be further oxidized during the ashing process and become a byproduct of the ashing process.

[0058] Also refer to Figure 2c and reference Figure 2d Oxygen source gas is used as the etching gas for ashing treatment to remove the patterned mask layer 205 and form byproducts 206 on the sacrificial layer 204. In practice, byproducts 206 may also be located between adjacent metal conductive layers 203.

[0059] Also refer to Figure 2d and Figure 2e An alkaline etching solution is used for etching to remove the sacrificial layer 204 and the byproducts 206 formed during the etching and ashing processes, and to expose the conductive metal layer 203, forming an isolation structure 207 between adjacent conductive metal layers 203.

[0060] In some embodiments, based on the etching rate and etching depth, the etching time required to completely etch through the initial conductive metal layer 203a without etching down to the insulating layer 202 can be obtained. Based on this etching time, the desired etching result can be obtained. Figure 2c The structure shown is illustrated. In other embodiments, etching time can be disregarded, and partial etching of the insulating layer (i.e., over-etching) can be performed during the etching process, where the insulating layer serves as an etching stop layer, thus simplifying the process flow.

[0061] Based on the semiconductor structure formation method provided in steps S101 to S105, this disclosure provides a semiconductor structure, with reference to... Figure 2e The semiconductor structure includes:

[0062] Substrate 201, on which an insulating layer 202 is formed;

[0063] The metal conductive layer 203 is located on the insulating layer 202;

[0064] An isolation structure 207 is located between adjacent conductive metal layers 203.

[0065] In this embodiment, the semiconductor structure formed by the above method includes an insulating layer and a metal conductive layer on the substrate, and an isolation structure between the metal conductive layers. On one hand, during the formation of this semiconductor structure, oxygen source gas is used as the etching gas in the etching and ashing processes. This ensures that the byproducts of the etching and ashing processes mainly consist of metal oxides, rather than the byproducts of the etching process mainly consisting of metal oxides and the byproducts of the ashing process mainly consisting of metal nitrides. Therefore, a single solution can be used to remove the byproducts of the etching and ashing processes in one step, thereby simplifying the process flow while improving the removal efficiency of byproducts. This reduces the possibility of short circuits caused by byproducts remaining between adjacent metal conductive layers, ultimately improving the yield of the semiconductor structure. On the other hand, since the sacrificial layer is a metal oxide layer and the byproducts generated during the etching and ashing processes are also metal oxides, a single solution can be used to etch and remove the sacrificial layer and byproducts in one step. Therefore, the process for forming this semiconductor structure is relatively simple.

[0066] In some embodiments, the method for forming the initial sacrificial layer may include steps S11 to S12, wherein:

[0067] Step S11: Planarize the initial metal conductive layer.

[0068] refer to Figure 3a The initial conductive metal layer 203a was planarized using chemical mechanical polishing (CMP) to obtain a flat surface free of scratches and impurities, which is beneficial for the subsequent formation of the initial sacrificial layer.

[0069] Step S12: Oxidation treatment is performed on the initial metal conductive layer using oxygen plasma to form an initial sacrificial layer on the surface of the initial metal conductive layer; wherein the materials of the initial metal conductive layer and the metal conductive layer include tungsten, and the material of the initial sacrificial layer includes tungsten oxide.

[0070] In some embodiments, the processing gases used in the formation of the initial sacrificial layer on the surface of the initial metallic conductive layer include oxygen, a hydrogen-nitrogen mixture, nitrogen, and argon; the flow rate of the processing gas ranges from 100 to 15,000 standard milliliters per minute; the pressure of the oxygen plasma generation region ranges from 10 to 10,000 millitors (mtorr); and the radio frequency power ranges from 10 to 10,000 watts (W).

[0071] refer to Figure 3bThe initial metal conductive layer 203a is oxidized using oxygen plasma to partially oxidize it, thereby forming an initial sacrificial layer 204a on the surface of the initial metal conductive layer 203a. When the initial metal conductive layer is made of tungsten, the chemical reaction during the oxidation process is as shown in formula (2), whereby tungsten reacts with oxygen and oxygen plasma to generate tungsten oxide W. x O y .

[0072] W+O2 / O * →W x O y Formula (2)

[0073] During implementation, firstly, refer to Figure 3c The planarized structure can be placed in the reaction chamber for preheating; secondly, refer to Figure 3d A processing gas, such as oxygen, a hydrogen-nitrogen mixture, and nitrogen, is introduced into the reaction chamber 30. Oxygen plasma 40a accumulates on the surface of the initial conductive metal layer 203a, causing the oxygen plasma 40a to react with the initial conductive metal layer 203a to generate the initial sacrificial layer 204a. Then, refer to... Figure 3e Nitrogen gas is continuously introduced into the reaction chamber 30 to cool the structure that forms the initial sacrificial layer 204a to room temperature; finally, nitrogen gas is continuously introduced, and the structure that forms the initial sacrificial layer is removed.

[0074] In this embodiment, the initial conductive metal layer is planarized, and a portion of the initial conductive metal layer is oxidized using oxygen plasma to form a uniform oxide film (i.e., the initial sacrificial layer). This improves the uniformity of the initial sacrificial layer, thereby enhancing its quality. Furthermore, since the initial sacrificial layer can be formed by oxidizing the initial conductive metal layer with oxygen plasma after the initial conductive layer is formed—that is, the initial sacrificial layer is formed incidentally after the initial conductive layer is formed—without requiring a dedicated deposition or spin-coating process, the process flow is simplified.

[0075] In some embodiments, the mask layer includes an amorphous carbon layer, and step S102, "based on the patterned mask layer, using oxygen source gas as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form a metal conductive layer and a sacrificial layer located on the metal conductive layer," may include steps S1021 and S1022, wherein:

[0076] Step S1021: A patterned amorphous carbon layer is formed on the initial sacrificial layer.

[0077] Step S1022: Based on the patterned amorphous carbon layer, the initial sacrificial layer and the initial metal conductive layer are etched using an in-situ oxygen plasma etching process to form a metal conductive layer and a sacrificial layer located on the metal conductive layer.

[0078] Correspondingly, step S103, "using oxygen source gas as etching gas for ashing treatment to remove the patterned mask layer," may include:

[0079] Step S1031: Ashing treatment is performed using oxygen plasma to remove the patterned amorphous carbon layer.

[0080] In this embodiment, the mask layer includes an amorphous carbon layer. During the in-situ oxygen plasma etching process, the oxygen plasma reacts with the amorphous carbon to generate carbon dioxide, thereby removing part of the patterned amorphous carbon layer. Compared with the metal conductive layer and the sacrificial layer, the etching selectivity of amorphous carbon is relatively high. Therefore, in the subsequent ashing process using oxygen source gas as the etching gas, damage to the metal conductive layer can be reduced.

[0081] In some embodiments, step S104, "performing an etching process using an alkaline etchant to remove the sacrificial layer and byproducts formed during the etching and ashing processes, and exposing the conductive metal layer," may include steps S1041 to S1044, wherein:

[0082] Step S1041: Pre-treat the surface of the sacrificial layer to remove the native oxides on the sacrificial layer and expose the sacrificial layer and the byproducts formed during the etching and ashing processes.

[0083] The pretreatment of the sacrificial layer surface may include wetting the surface of the sacrificial layer and cleaning the surface of the sacrificial layer with a small amount of diluted hydrofluoric acid (DHF) solution. This can remove the natural oxides and some micro dust particles on the sacrificial layer, thereby exposing the sacrificial layer and the by-products formed during the etching and ashing processes, which is beneficial for the subsequent removal of these by-products.

[0084] In some embodiments, the volume ratio of hydrogen fluoride to deionized water in the hydrogen fluoride-deionized water mixed solution ranges from 10:1 to 1000:1. In this embodiment, by setting the range of the volume ratio of hydrogen fluoride to deionized water in the hydrogen fluoride-deionized water mixed solution, the rate of removal of native oxides from the sacrificial layer can be increased.

[0085] Step S1042: The sacrificial layer and byproducts formed during the etching and ashing processes are removed using an alkaline etching solution to expose the conductive metal layer.

[0086] Step S1043: Clean the surface of the metal conductive layer to remove any residual alkaline corrosion solution.

[0087] Here, deionized water can be used to clean the surface of the metal conductive layer to remove residual alkaline corrosion solution; alternatively, the alkaline corrosion solution can be neutralized first with an excess of acidic solution, and then deionized water can be used to clean the residual acidic solution. In this case, the acidic solution used should not damage the surface of the metal conductive layer.

[0088] Step S1044: Dry the metal conductive layer.

[0089] As semiconductor process linewidths continue to shrink, the centrifugal drying technique, which requires high-speed rotation to subject the liquid to centrifugal force and cause it to disappear from the surface, increases the risk of semiconductor structure collapse. In this embodiment, to reduce the risk of semiconductor structure collapse, isopropanol (IPA) drying technology can be used to dry the metal conductive layer. Specifically, the metal conductive layer can be dried in a nitrogen atmosphere, which reduces the possibility of oxygen in the air re-oxidizing the metal conductive layer, thereby minimizing the impact on the conductivity of the metal conductive layer.

[0090] The principle of IPA drying is explained below. IPA drying is a technology that utilizes the heating, vaporization, evaporation, and surface tension of IPA to achieve dehydration and drying. The IPA steam system includes a steam tank, a steam zone, and a condensation tank. In the steam tank, IPA is heated to form steam, which rises to form a relatively stable steam zone with high concentration and temperature. The uppermost layer is the condensation zone formed by cooling water pipes.

[0091] Before drying, the conductive metal layer needs to be immersed in liquid IPA. Due to miscibility, the water on the surface of the conductive metal layer dissolves into the IPA, replacing it with liquid IPA. The conductive metal layer moves up and down in the system via a chain. When it reaches the steam zone, the steam condenses on the surface due to the low temperature of the conductive metal layer, forming a large amount of liquid IPA that washes the surface. After the temperature of the conductive metal layer rises, the conductive metal layer carrying the IPA vapor returns to the condensation zone. The IPA vapor condenses and liquefies, leaving the surface through multiple forces such as gravity, surface tension, and volatilization, thus achieving the drying effect.

[0092] In other embodiments, the Marangoni drying technique can also be used to dry the conductive metal layer. The Marangoni drying technique differs fundamentally from the IPA drying technique. The Marangoni drying technique achieves drying by drawing water back to the surface through a surface tension gradient, while the IPA drying technique relies on water evaporation. Using the Marangoni drying technique not only saves on the amount of IPA used but also overcomes the dehydration difficulties in deep and narrow channels.

[0093] Step S105, “forming an isolation structure between adjacent conductive metal layers”, may include: forming a first dielectric layer and a second dielectric layer sequentially between adjacent conductive metal layers to form an isolation structure.

[0094] The first dielectric layer can be made of insulating materials such as silicon nitride or silicon oxide, and the second dielectric layer can be made of silicon nitride or silicon oxide doped with impurities (such as fluorine, carbon, or boron). The doped impurity ions can reduce the dielectric constant of silicon nitride or silicon oxide, thereby reducing the parasitic capacitance between the metal conductive layers and thus reducing the power consumption of the device.

[0095] The first dielectric layer can be formed by chemical vapor deposition, physical vapor deposition, atomic layer deposition, low-pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition, spin coating, or any other suitable process. The second dielectric layer can be formed by first forming a dielectric layer by chemical vapor deposition, then doping the dielectric layer with impurity ions by ion doping, and finally annealing the dielectric layer doped with impurity ions to obtain the second dielectric layer.

[0096] In this embodiment of the present disclosure, since a first dielectric layer and a second dielectric layer are sequentially formed on the metal conductive layer to form an isolation structure, that is, the formed isolation structure includes a first dielectric layer and a second dielectric layer, the two different dielectric layers work together to provide isolation, thereby improving the isolation performance of the isolation structure.

[0097] refer to Figure 4 A first dielectric layer 207a and a second dielectric layer 207b are sequentially formed between adjacent metal conductive layers 203 to form an isolation structure. It can be seen that the first dielectric layer 207a is formed on the right side wall of the left metal conductive layer 203 and the left side wall of the right metal conductive layer 203, and the second dielectric layer 207b fills the remaining space between the metal conductive layers 203.

[0098] This disclosure also provides a method for forming a semiconductor structure, referencing... Figure 5a The method includes steps S501 to S505, wherein:

[0099] Step S501: A substrate is provided, on which an insulating layer, an initial barrier layer, an initial metal conductive layer, an initial sacrificial layer and a mask layer are formed in sequence, wherein the initial sacrificial layer includes a metal oxide layer.

[0100] Here, an initial barrier layer is also formed on the substrate between the insulating layer and the initial metal conductive layer. The initial barrier layer can prevent the metal in the initial metal conductive layer from diffusing into the insulating layer.

[0101] refer to Figure 5bAn insulating layer 202, an initial barrier layer 208a, an initial metal conductive layer 203a, an initial sacrificial layer 204a, and a mask layer 205a are sequentially formed on a substrate 201. The insulating layer 202 can be a silicon nitride layer, the initial metal conductive layer 203a can be an initial tungsten layer, the initial sacrificial layer 204a can be a tungsten oxide layer, the initial barrier layer 208a can be a titanium nitride layer, and the mask layer 205a can be an amorphous carbon layer.

[0102] In step S502, based on the patterned mask layer, oxygen source gas is used as the etching gas to etch the initial sacrificial layer, the initial metal conductive layer, and the initial barrier layer to form a trench, and a barrier layer, a metal conductive layer, and a sacrificial layer are formed in sequence on both sides of the trench.

[0103] The material of the metallic conductive layer may include tungsten.

[0104] refer to Figure 5c A patterned mask layer 205 is formed on the initial sacrificial layer 204a. (See reference) Figure 5c and Figure 5d Based on the patterned mask layer 205, oxygen source gas is used as the etching gas to etch the initial sacrificial layer 204a, the initial conductive metal layer 203a, and the initial barrier layer 208a. Simultaneously, a portion of the insulating layer 202 is also etched to form a trench 207'. A barrier layer 208, a conductive metal layer 203, and a sacrificial layer 204 are then formed and stacked sequentially on both sides of the trench 207'. Here, the depth of the trench 207' is less than the sum of the thicknesses of the barrier layer, the conductive metal layer, the sacrificial layer, and the insulating layer.

[0105] In some embodiments, the depth of trench 207' can be equal to the sum of the thicknesses of the barrier layer, the conductive metal layer, and the sacrificial layer.

[0106] In step S503, oxygen source gas is used as the etching gas for ashing treatment to remove the patterned mask layer.

[0107] Also refer to Figure 5d and Figure 5e Oxygen source gas is used as the etching gas for ashing treatment to remove the patterned mask layer 205. During the etching and ashing processes, byproducts 206 formed will adhere to the surface of the sacrificial layer 204.

[0108] In step S504, an alkaline etching solution is used for etching to remove the sacrificial layer and byproducts formed during the etching and ashing processes, and to expose the conductive metal layer.

[0109] Both the sacrificial layer and the byproducts can be tungsten oxide, thus allowing for the removal of both in one step.

[0110] Also refer to Figure 5e and Figure 5f An alkaline etching solution is used for etching to remove the sacrificial layer 204 and the byproducts 206 formed during the etching and ashing processes, and to expose the conductive metal layer 203.

[0111] Steps S503 and S504 can be implemented by referring to steps S103 and S104 respectively.

[0112] Step S505: Form an isolation structure in the trench.

[0113] refer to Figure 5g First, an atomic layer deposition (ALD) process can be used to deposit a first dielectric layer material 207a' in the trench, which can improve the flatness and quality of the subsequently formed dielectric layer. Then, a plasma-enhanced chemical deposition (PECD) process is used to deposit a second dielectric layer material 207b', where the second dielectric layer material 207b' fills the remaining space in the trench. Since ALD requires more time than PCD for depositing the same thickness of dielectric layer material, PCD can shorten the time for forming the isolation structure. After depositing the second dielectric layer material 207b', it can be doped with impurity ions to reduce its dielectric constant. Finally, a third dielectric layer material 207c' is deposited on the second dielectric layer material 207b' using a low-pressure chemical vapor deposition (LPCVD) process. Since LCVD requires less time than plasma-enhanced chemical vapor deposition (PECVD) for depositing the same thickness of dielectric layer material, the time required to form the isolation structure can be further shortened. Thus, by achieving a predetermined height for the isolation structure, on the one hand, the quality of the dielectric layer in the isolation structure can be improved, and the time required to form the isolation structure can be shortened; on the other hand, since a lower dielectric constant between adjacent conductive metal layers results in a smaller parasitic capacitance, reducing the dielectric constant of the second dielectric layer material can reduce the parasitic capacitance between adjacent conductive metal layers, thereby reducing the power consumption of the device.

[0114] refer to Figure 5h The dielectric layer material above the metal conductive layer 203 is removed to form an isolation structure 207. The isolation structure 207 includes a first dielectric layer 207a located on both sides of the metal conductive layer 203 (and at the bottom of the trench) and a second dielectric layer 207b in contact with the first dielectric layer 207a. Figure 5h It can be seen that the first dielectric layer 207a and the second dielectric layer 207b fill the gaps between adjacent metal conductive layers 203.

[0115] Based on the semiconductor structure formation method provided in steps S501 to S505, this disclosure provides a semiconductor structure, with reference to... Figure 5h The semiconductor structure also includes a barrier layer 208 located between the insulating layer 202 and the metal conductive layer 203.

[0116] In the several embodiments provided in this disclosure, it should be understood that the disclosed structures and methods can be implemented in a non-target manner. The structural embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components may be combined, or integrated into another system, or some features may be ignored or not executed. In addition, the various components shown or discussed are coupled or directly coupled to each other.

[0117] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0118] The features disclosed in the several method or structural embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new method or structural embodiments.

[0119] The above descriptions are merely some embodiments of this disclosure, but the protection scope of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this disclosure should be included within the protection scope of this disclosure. Therefore, the protection scope of this disclosure should be determined by the scope of the claims.

Claims

1. A method for forming a semiconductor structure, characterized in that, include: A substrate is provided on which an insulating layer, an initial metal conductive layer, an initial sacrificial layer and a mask layer are formed in sequence, the initial sacrificial layer comprising a metal oxide layer; Based on a patterned mask layer, oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form a metal conductive layer and a sacrificial layer located on the metal conductive layer, so that the by-products formed during the etching process include metal oxides. Oxygen source gas is used as etching gas for ashing treatment to remove the patterned mask layer, and the byproducts formed during the ashing treatment include metal oxides. An alkaline etching solution is used for etching to remove the sacrificial layer and the byproducts formed during the etching and ashing processes, and to expose the conductive metal layer. An isolation structure is formed between adjacent conductive metal layers.

2. The method according to claim 1, characterized in that, The method for forming the initial sacrificial layer includes: The initial metal conductive layer is planarized. The initial metal conductive layer is oxidized using oxygen plasma to form the initial sacrificial layer on the surface of the initial metal conductive layer. The initial metal conductive layer and the material of the metal conductive layer include tungsten, and the material of the initial sacrificial layer includes tungsten oxide.

3. The method according to claim 1, characterized in that, The mask layer includes an amorphous carbon layer; based on the patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form a metal conductive layer and a sacrificial layer located on the metal conductive layer, including: A patterned amorphous carbon layer is formed on the initial sacrificial layer; Based on the patterned amorphous carbon layer, the initial sacrificial layer and the initial metal conductive layer are etched using an in-situ oxygen plasma etching process to form the metal conductive layer and the sacrificial layer located on the metal conductive layer.

4. The method according to claim 3, characterized in that, Using oxygen source gas as the etching gas for ashing treatment to remove the patterned mask layer includes: The ashing process is performed using oxygen plasma to remove the patterned amorphous carbon layer.

5. The method according to any one of claims 1 to 4, characterized in that, The byproducts formed during the etching and ashing processes include tungsten oxide.

6. The method according to any one of claims 1 to 4, characterized in that, The etching process employs an alkaline etching solution to remove the sacrificial layer and byproducts formed during the etching and ashing processes, thereby exposing the conductive metal layer, including: The surface of the sacrificial layer is pretreated to remove the native oxides on the sacrificial layer and expose the sacrificial layer and the byproducts formed during the etching and ashing processes; The sacrificial layer and the byproducts formed during the etching and ashing processes are removed using an alkaline etching solution, exposing the conductive metal layer. Clean the surface of the metal conductive layer of any residual alkaline corrosive solution; The metal conductive layer is dried.

7. The method according to any one of claims 1 to 4, characterized in that, The alkaline corrosive solution includes a mixture of ammonia and deionized water, wherein the volume ratio of ammonia to deionized water in the mixture ranges from 5:1 to 1000:

1.

8. The method according to claim 6, characterized in that, The metal conductive layer is dried using isopropanol and nitrogen.

9. The method according to any one of claims 1 to 4, characterized in that, An isolation structure is formed between adjacent metallic conductive layers, comprising: A first dielectric layer and a second dielectric layer are sequentially formed between adjacent metallic conductive layers to form the isolation structure.

10. The method according to claim 1, characterized in that, An initial barrier layer is also formed on the substrate between the insulating layer and the initial metal conductive layer; Based on a patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer and the initial metal conductive layer to form a metal conductive layer and a sacrificial layer located on the metal conductive layer, including: Based on a patterned mask layer, an oxygen source gas is used as the etching gas to etch the initial sacrificial layer, the initial metal conductive layer, and the initial barrier layer to form a trench, and a barrier layer, the metal conductive layer, and the sacrificial layer are formed in sequence on both sides of the trench. Forming an isolation structure between adjacent conductive metal layers includes: forming the isolation structure in the trench.

11. The method according to claim 2, characterized in that, In the process of forming the initial sacrificial layer on the surface of the initial metallic conductive layer, the processing gases used include: oxygen, a hydrogen-nitrogen mixture, nitrogen, and argon; the flow rate of the processing gases ranges from 100 to 15,000 standard milliliters per minute; the pressure of the oxygen plasma generation region ranges from 10 to 10,000 millitors; and the radio frequency power ranges from 10 to 10,000 watts.

12. A semiconductor structure, characterized in that, The semiconductor structure is formed using the method described in any one of claims 1 to 11, comprising: A substrate on which an insulating layer is formed; A metal conductive layer located on the insulating layer; An isolation structure located between adjacent conductive metal layers.

13. The structure according to claim 12, characterized in that, The material of the metallic conductive layer includes tungsten.

14. The structure according to claim 12, characterized in that, The isolation structure includes: a first dielectric layer located on both sides of the metal conductive layer and a second dielectric layer in contact with the first dielectric layer; wherein the first dielectric layer and the second dielectric layer fill the gap between adjacent metal conductive layers.

15. The structure according to claim 12, characterized in that, Also includes: A barrier layer located between the insulating layer and the metal conductive layer.

Images