Semiconductor structure and grinding method thereof

Abstract

The invention provides a semiconductor structure and a grinding method thereof. The grinding method of the semiconductor structure comprises the steps that a substrate is provided, the substrate is provided with a through hole and a metal material at least filling the through hole, and the surface of the metal material is exposed out of the substrate; and the exposed surface of the metal material is ground through a grinding process, grinding liquid used in the grinding process contains a metal protective agent, and the metal protective agent is selectively adsorbed to the surface of the metal material and continuously acts until the grinding process is finished. According to the grinding method of the semiconductor structure, the surface of the metal material can be effectively prevented from making contact with water and oxygen in air, generation of metal oxide is restrained, and therefore the production yield and use reliability of a semiconductor device are improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and particularly to a semiconductor structure and a grinding method thereof. Background Art

[0002] With the development of semiconductor technology, the feature size of semiconductor devices has been continuously reduced to the deep sub-micron stage. To achieve high-integration and high-performance semiconductor devices, copper (Cu) materials with lower resistivity have been widely used in metal interconnect technology, and low dielectric constant (Low-k) materials are filled between metal layers to improve signal delay and crosstalk caused by parasitic capacitance.

[0003] Currently, after the copper chemical mechanical polishing (CU CMP) process, the surface of the copper metal layer is directly exposed to the air and is extremely easy to oxidize to form copper oxide (CuO x ). When subsequent processes use ammonia (NH3) plasma treatment, although the copper oxide can be reduced to copper, a tiny honeycomb-like void structure is easily formed on the copper during the treatment process. This structure is prone to aggregating particulate impurities, ions, or air during subsequent thin film deposition processes. With the superposition of processes, it will eventually lead to defects such as bumps and bubbles, seriously affecting the reliability of the device.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] Based on this, the embodiments of this application provide a semiconductor structure and a grinding method thereof, which can effectively block the contact between the surface of the metal material and water and oxygen in the air, inhibit the generation of metal oxides, and thus improve the production yield and use reliability of semiconductor devices.

[0006] According to some embodiments, on the one hand, this application provides a grinding method for a semiconductor structure, including:

[0007] Providing a substrate having a through hole and at least a metal material filling the through hole, the surface of the metal material being exposed to the outside of the substrate;

[0008] Using a grinding process to grind the exposed surface of the metal material, the grinding fluid used in the grinding process contains a metal protection agent, and the metal protection agent selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

[0009] In some embodiments, the metal protection agent contains a phosphite compound.

[0010] In some embodiments, the mass percentage range of the metal protectant in the abrasive liquid includes 0.1 wt% to 10 wt%.

[0011] In some embodiments, after the grinding process is completed, the method for grinding the semiconductor structure further includes:

[0012] Introducing oxygen-containing ions by means of a plasma process, and reacting the oxygen-containing ions with the metal protectant to remove the metal protectant.

[0013] In some embodiments, after removing the metal protectant, the method for grinding the semiconductor structure further includes:

[0014] Forming an isolation layer on the surface of the ground metal material by means of a plasma deposition process.

[0015] In some embodiments, the grinding process includes a chemical mechanical polishing process.

[0016] According to some embodiments, on the other hand, the present application further provides a semiconductor structure, including a substrate having a through hole and at least a metal layer filling the through hole;

[0017] Wherein, the metal layer is formed by performing a grinding process on the surface of the exposed metal material, and the abrasive liquid used in the grinding process contains a metal protectant, and the metal protectant selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

[0018] In some embodiments, the metal protectant contains a phosphite compound.

[0019] In some embodiments, the mass percentage range of the metal protectant in the abrasive liquid includes 0.1 wt% to 10 wt%.

[0020] In some embodiments, the metal protectant adsorbed on the surface of the metal material is removed by reacting with oxygen-containing ions, and the oxygen-containing ions are introduced by means of a plasma process.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application.

[0022] The embodiments of the present application can / at least have the following advantages:

[0023] In the present application, a metal protectant is added to the polishing liquid used in the polishing process, and a metal protectant that can selectively adsorb on the surface of the metal material is selected to form a stable adsorption layer, effectively blocking the contact between the surface of the metal material and water and oxygen in the air, inhibiting the formation of metal oxides, and avoiding the generation of honeycomb-like cavity structures in subsequent processes due to the residue of metal oxides, thereby improving the production yield and service reliability of semiconductor devices.

[0024] Moreover, in the embodiments of the present application, there is no need to additionally add a pre-protection step. The surface protection of the metal material is achieved by adding a metal protectant to the polishing liquid used in the polishing process. The process flow is simple and the process time is not affected.

[0025] Other advantages, objectives, and features of the present application will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present application. The objectives and other advantages of the present application can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objectives, and advantages of the present application will become more obvious.

[0027] Figure 1 Schematic flow chart of a method for polishing a semiconductor structure provided in some embodiments of the present application;

[0028] Figure 2 Schematic cross-sectional structure diagram of the structure obtained after filling a through hole with a metal material in some embodiments of the present application;

[0029] Figure 3 Schematic cross-sectional structure diagram of the structure obtained after a metal protectant adsorbs on the surface of a metal material in some embodiments of the present application;

[0030] Figure 4 Schematic cross-sectional structure diagram of a metal protectant isolating water and oxygen in the air in some embodiments of the present application;

[0031] Figure 5 Schematic cross-sectional structure diagram of the structure obtained after removing the metal protectant in some embodiments of the present application;

[0032] Figure 6 Schematic cross-sectional structure diagram of a semiconductor structure provided in some embodiments of the present application.

[0033] Description of the reference numerals:

[0034] 110, substrate; 121, through hole; 122, metal material; 123, metal layer; 130, BD layer, 140, TEOS layer;

[0035] 210. Metal protectant; 210'. By-product. Detailed implementation manners

[0036] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that when the terms "comprising" and / or "including" are used in this specification, the presence of the stated features, integers, steps, operations, elements and / or components can be determined, but one or more other features, integers, steps, operations, elements, components and / or groups are not excluded from the presence or addition. At the same time, as used herein, the term "and / or" includes any and all combinations of the related listed items.

[0039] It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present disclosure schematically. Although only the components related to the present disclosure are shown in the diagrams and are not drawn according to the number, shape and size of the components in actual implementation, the types, numbers and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0040] Currently, after the copper chemical mechanical polishing (CU CMP) process, the surface of the copper metal layer is directly exposed to the air and is extremely easy to oxidize to form copper oxide (CuO x ). When the subsequent process uses ammonia (NH3) plasma treatment, although the copper oxide can be reduced to copper, a tiny honeycomb-like void structure is easily formed on the copper during the treatment process. This structure is prone to aggregating particulate impurities, ions or air during the subsequent thin film deposition process, and with the process stacking, it will ultimately lead to defects such as bumps and bubbles, seriously affecting the device reliability.

[0041] Based on this, the present application hopes to provide a solution that can solve the above technical problems, effectively block the contact between the surface of the metal material and water and oxygen in the air, inhibit the formation of metal oxides, and thus improve the production yield and service reliability of semiconductor devices. The detailed content will be elaborated in the subsequent embodiments.

[0042] According to some embodiments, on the one hand, the present application provides a grinding method for a semiconductor structure. Please refer to Figure 1 , the grinding method for the semiconductor structure may specifically include S100 to S200:

[0043] S100: Provide a substrate, the substrate has a through hole and at least a metal material filling the through hole, and the surface of the metal material is exposed to the outside of the substrate.

[0044] S200: Use a grinding process to grind the exposed surface of the metal material. The grinding fluid (Slurry) used in the grinding process contains a metal protector, and the metal protector selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

[0045] The above grinding method for the semiconductor structure adds a metal protector to the grinding fluid used in the grinding process, and selects a metal protector that can selectively adsorb on the surface of the metal material to form a stable adsorption layer, effectively blocking the contact between the surface of the metal material and water and oxygen in the air, inhibiting the formation of metal oxides, and avoiding the generation of honeycomb-like void structures in subsequent processes due to the residue of metal oxides, thereby improving the production yield and service reliability of semiconductor devices.

[0046] Moreover, the above grinding method for the semiconductor structure does not require an additional pre-protection step. The surface protection of the metal material is achieved by adding a metal protector to the grinding fluid used in the grinding process. The process flow is simple and the process time is not affected.

[0047] The following combines Figures 2 to 5 to describe in detail the grinding method for the semiconductor structure provided by the embodiments of the present application.

[0048] Please refer to Figure 2 , in step S100, provide a substrate 110. The substrate 110 has a through hole 121 and at least a metal material 122 filling the through hole 121, and the surface of the metal material 122 is exposed to the outside of the substrate 110.

[0049] Exemplarily, the substrate 110 can be composed of a semiconductor material, an insulating material, a conductive material, or any combination of their material types. The substrate 110 can be a single-layer structure or a multi-layer structure. For example, the substrate 110 can be a silicon (Si) substrate, a silicon germanium (SiGe) substrate, a silicon germanium carbide (SiGeC) substrate, a silicon carbide (SiC) substrate, a gallium arsenide (GaAs) substrate, an indium arsenide (InAs) substrate, an indium phosphide (InP) substrate, or other III / V semiconductor substrates or II / VI semiconductor substrates. Or, for another example, the substrate 110 can be a layered substrate including a stack of, for example, Si and SiGe, a stack of Si and SiC, silicon on insulator (SOI), or silicon germanium on insulator.

[0050] The metal material 122 can be used to fabricate metal interconnect layers in the back-end-of-line (BEOL) of semiconductor devices. In some possible implementation manners, as Figure 2 shown, before forming the metal interconnect layer, a BD (Black Diamond, i.e., silicon carbide with a low dielectric constant) layer 130 and a TEOS (tetraethyl orthosilicate) layer 140 are formed in a bottom-up stacked manner on the substrate 110 on which the front-end devices are formed. The BD layer 130 and the TEOS layer 140 can avoid mechanical stress from damaging the substrate 110 and the front-end devices in the substrate 110 when subsequently grinding and filling the metal material 122.

[0051] The embodiments of the present application do not limit the specific type of the metal material 122. For example, the metal material 122 can be a single-metal material such as copper (Cu), aluminum (Al), tungsten (W), or cobalt (Co). Or, for another example, the metal material 122 can be a mixed-metal material such as Cu / Co or Cu / W.

[0052] For the convenience of description, in the subsequent embodiments of this specification, an example is given with the metal material 122 including copper.

[0053] Please refer to Figure 3 , in step S200, a grinding process is used to grind the exposed surface of the metal material 122. The grinding fluid used in the grinding process contains a metal protectant 210, and the metal protectant 210 can selectively adsorb on the surface of the metal material 122 and continuously act until the end of the grinding process.

[0054] Due to the selective adsorption of the metal protectant 210, there is no need to strictly control the time interval (Q-time) between the above-mentioned grinding process and the subsequent process (such as a deposition process). In the traditional grinding method, if the Q-time is too long, the exposed metal material 122 will be oxidized, resulting in an increase in defects. However, the embodiments of the present application utilize the metal protectant 210 that can selectively adsorb on the surface of the metal material 122 to eliminate this limitation, asFigure 4 As shown, the metal protective agent 210 can selectively adsorb on the surface of the metal material 122, isolate water (H2O) and oxygen in the air, and prevent the exposed metal material 122 from oxidizing, thus greatly expanding the production window and being beneficial to improving the production efficiency of semiconductor devices.

[0055] Please continue to refer to Figure 3 , the metal protective agent 210 selectively adsorbs only on the surface of the metal material 122, and will not adsorb or adhere to non-target surfaces (such as the surface of the substrate 110 or the BD layer 130), avoiding performance changes caused by contamination of non-metal surfaces and helping to ensure the normal progress of subsequent processes.

[0056] In the embodiments of the present application, the type of the metal protective agent 210 is not specifically limited as long as it can selectively adsorb on the surface of the metal material 122. The selection of the metal protective agent 210 should be based on its interaction characteristics with the surface of the metal material 122 to ensure that it can selectively adsorb on the surface of the metal material 122, effectively protecting the metal surface from oxidation.

[0057] In some embodiments, the metal protective agent 210 contains phosphite compounds.

[0058] Phosphite compounds are a class of organophosphorus compounds, and their molecular structure contains a phosphorus atom (P) connected to an oxygen atom (O) and an organic group (R, such as an alkyl or aryl group). Phosphite compounds have strong metal affinity. Taking the metal material 122 including copper as an example, the unsaturated bonds or free electrons on the copper surface can form coordination bonds or van der Waals forces with the phosphorus atom or oxygen atom in the phosphite, thereby achieving selective adsorption.

[0059] At the same time, the organic group (R) of the phosphite makes it have certain hydrophobicity, while non-target surfaces (such as the surface of the substrate 110 or the BD layer) are usually hydrophilic or have silicon-oxygen bonds (Si-O), reducing the interaction between the phosphite and them. Therefore, the phosphite can selectively adsorb on the surface of the metal material 122 and will not adsorb on the surface of non-target surfaces (such as substrate materials and BD materials), thus ensuring that subsequent processes are not disturbed.

[0060] In the embodiments of the present application, the mass percentage of the metal protective agent 210 in the polishing liquid is not specifically limited.

[0061] In some embodiments, the mass percentage range of the metal protective agent 210 in the polishing liquid includes 0.1 wt% to 10 wt%. For example, the mass percentage of the metal protective agent 210 in the polishing liquid can be 0.1 wt%, 1 wt%, 2 wt%, 5 wt% or 10 wt% and so on.

[0062] If the mass percentage of the metal protectant 210 is too low, it may not be able to fully cover the surface of the metal material 122, resulting in insufficient protection and the possibility of oxidation on the surface of the metal material 122. If the mass percentage of the metal protectant 210 is too high, it may cause the metal protectant 210 to remain on non-target surfaces (such as the surface of the substrate 110 or the BD layer), or form an overly thick adsorption layer on the surface of the metal material 122, increasing the difficulty of subsequent removal. The above grinding method controls the mass percentage of the metal protectant 210 between 0.1 wt% and 10 wt%, which can ensure the effective protection of the surface of the metal material 122 by the metal protectant 210 during grinding, while avoiding the residue caused by excessive metal protectant 210 or increasing the difficulty of subsequent removal.

[0063] It should be noted that the type of grinding process used in step S200 of the present application embodiment is not specifically limited either. In some embodiments, the grinding process may include a chemical mechanical polishing (CMP) process or an electrochemical mechanical grinding process, etc., but is not limited thereto. The embodiments of the present application are applicable to other processes that use a grinding fluid for grinding or polishing.

[0064] In some embodiments, after the grinding process is completed, an oxygen-containing ion can be introduced by a plasma process (Plasma Treatment) to react with the metal protectant 210 to remove the metal protectant 210.

[0065] It should be noted that the oxygen-containing ions described in the above steps are oxygen-containing ions with high reactivity, which can quickly participate in chemical reactions, especially redox reactions. Exemplarily, the oxygen-containing ions may include, but are not limited to, oxygen ions (O - ), superoxide ions (O2 - ), or peroxide ions (O2 2- ), etc. Among them, the peroxide ion (O2 2- ) can be, for example, a hydroperoxide ion (HO2 - ), but is not limited thereto.

[0066] Taking the metal protectant 210 containing a phosphite compound as an example, the oxygen-containing ions (such as O - or O2 - ) have strong oxidizing properties and can react with the phosphorus atom and the organic group in the phosphite. Please refer to Figure 5 Understand that during the reaction process, the phosphorus atom does not disappear, but is oxidized and combined with other reaction products to form a phosphorus-containing by-product 210'. The phosphorus-containing by-product 210' (such as phosphorus pentoxide) can escape in the form of a gas and is easy to remove, so it will not have an adverse impact on subsequent processes.

[0067] In some embodiments, after removing the metal protectant 210, an isolation layer may be formed on the surface of the polished metal material 122 through a plasma deposition process.

[0068] The above isolation layer can isolate and protect the polished metal material 122. Forming the isolation layer in a timely manner at the end of the polishing process can effectively prevent the oxidation of the metal material 122. Moreover, the isolation layer can also prevent the diffusion of metal ions to the subsequent layer, and has an inhibitory effect on metal electromigration.

[0069] As an example, the plasma deposition process may include, but is not limited to, plasma enhanced chemical vapor deposition (PECVD) or plasma enhanced atomic layer deposition (PEALD), etc.

[0070] Exemplarily, as Figure 5 shown, a nitride doped silicon carbide (NDC) thin film can be formed as an isolation layer on the surface of the polished metal material 122 through a plasma deposition process.

[0071] The NDC thin film has high chemical stability and low permeability, and can effectively prevent the external environment (such as water vapor and oxygen in the air) from contacting the metal material 122, reducing metal oxidation. At the same time, the NDC thin film can also effectively prevent the diffusion of metal ions (such as Cu + ) to the subsequent layer (such as the adjacent dielectric layer), avoiding problems such as short circuit, leakage current or device failure caused by metal diffusion.

[0072] In the embodiments of the present application, the polished metal material 122 can be used to prepare a metal interconnect structure in a semiconductor device. Specifically, after the metal material 122 is processed by a polishing process, the surface flatness and cleanliness are significantly improved, and it is suitable for preparing high-density and low-resistivity metal interconnect lines, thereby effectively improving the performance and reliability of the semiconductor device. Adopting the polishing method provided by the present application is beneficial to ensuring the stability and consistency of the metal interconnect structure during the semiconductor manufacturing process, and further improving the production yield and use reliability of the semiconductor device.

[0073] According to some embodiments, on the other hand, the present application also provides a semiconductor structure. Please refer to Figure 6 , the semiconductor structure includes a substrate 110, and the substrate 110 has a through hole 121 and at least a metal layer 123 filling the through hole 121.

[0074] Among them, the metal layer 123 is formed by performing a grinding process on the surface of the exposed metal material. The grinding fluid used in the grinding process contains a metal protectant, and the metal protectant selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

[0075] In the above semiconductor structure, since the metal layer 123 is formed by performing a grinding process on the surface of the exposed metal material, and the grinding fluid used in the grinding process contains a metal protectant that selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process, the metal protectant can form a stable adsorption layer on the surface of the metal material, thereby effectively blocking the contact between the surface of the metal layer and water and oxygen in the air and inhibiting the formation of metal oxides. Therefore, the honeycomb-like void structure caused by metal oxide residues does not appear in the above semiconductor structure, which is beneficial to improving the production yield and use reliability of semiconductor devices.

[0076] In addition, no additional pre-protection step is required in the preparation process of this semiconductor structure. By directly adding a metal protectant to the grinding fluid of the grinding process, a high-quality metal layer 123 can be made. The preparation process flow is simple and does not affect the process time.

[0077] In some embodiments, during the formation of this semiconductor structure, a grinding process is performed on the surface of the exposed metal material using a grinding fluid containing a phosphite compound to form the metal layer 123.

[0078] In some embodiments, during the formation of this semiconductor structure, the mass percentage range of the metal protectant in the grinding fluid used is from 0.1 wt% to 10 wt%.

[0079] In some embodiments, during the formation of this semiconductor structure, the metal protectant adsorbed on the surface of the metal material is removed by reacting with oxygen-containing ions, and the oxygen-containing ions are introduced by a plasma process.

[0080] It should be noted that the semiconductor structures in the embodiments of the present application can all be prepared by implementing the corresponding grinding methods of the semiconductor structures. Therefore, the technical features between the method embodiments and the structure embodiments can be mutually replaced and supplemented without conflict, so that those skilled in the art can learn about the technical content of the present application.

[0081] Without departing from the spirit or scope of the present application, various modifications and changes can be made in the present application, which are obvious to those skilled in the art. Therefore, the present application is intended to cover the modifications and changes of the present application that fall within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in the embodiments of the present application can be combined with each other without contradiction.

[0082] In the description of this specification, the descriptions referring to terms such as "some embodiments", "by way of example", "exemplarily", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0083] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0084] The above-described embodiments only represent several implementation manners of the present application. The descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A grinding method for a semiconductor structure, characterized in that, Including: Providing a substrate having vias and a metal material filling at least the vias, with the surface of the metal material exposed to the outside of the substrate; Performing a grinding process on the exposed surface of the metal material, wherein the grinding fluid used in the grinding process contains a metal protection agent that selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

2. The polishing method of the semiconductor structure according to claim 1, wherein The metal protection agent contains a phosphite compound.

3. The polishing method of the semiconductor structure according to claim 1, wherein The mass percentage range of the metal protection agent in the grinding fluid includes 0.1 wt% to 10 wt%.

4. The polishing method of the semiconductor structure according to claim 1, wherein After the grinding process ends, the method for grinding the semiconductor structure further includes: Introducing oxygen-containing ions by a plasma process to react the oxygen-containing ions with the metal protection agent to remove the metal protection agent.

5. The polishing method of the semiconductor structure according to claim 4, wherein After removing the metal protection agent, the method for grinding the semiconductor structure further includes: Forming an isolation layer on the surface of the ground metal material by a plasma deposition process.

6. The polishing method of the semiconductor structure according to claim 1, wherein The grinding process includes a chemical mechanical grinding process.

7. A semiconductor structure, characterized in that, Including a substrate having vias and a metal layer filling at least the vias; Wherein, the metal layer is formed by performing a grinding process on the exposed surface of the metal material, and the grinding fluid used in the grinding process contains a metal protection agent that selectively adsorbs on the surface of the metal material and continuously acts until the end of the grinding process.

8. The semiconductor structure according to claim 7, wherein, The metal protection agent contains a phosphite compound.

9. The semiconductor structure according to claim 7, wherein, The mass percentage range of the metal protection agent in the grinding fluid includes 0.1 wt% to 10 wt%.

10. The semiconductor structure according to claim 7, characterized in that, The metal protection agent adsorbed on the surface of the metal material is removed by reacting with oxygen-containing ions, and the oxygen-containing ions are introduced by a plasma process.

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