Opening structures and methods of forming the same, contact plugs and methods of forming the same

Abstract

An opening structure and its forming method, a contact plug and its forming method, the forming method of the opening structure, a substrate is provided, the target layer is formed in the substrate, the surface of the target layer is exposed by the substrate; a ring-shaped spacer is formed on the surface of the target layer, the ring-shaped spacer has a central through hole in the middle, the central through hole exposes part of the surface of the target layer; a medium layer is formed to cover the substrate, the target layer and the ring-shaped spacer; the medium layer is etched to form an etching hole in the medium layer, the etching hole and the central through hole constitute the opening structure. By forming the ring-shaped spacer, when the etching hole is curved or deviated in position during the formation of the etching hole in the medium layer, the ring-shaped spacer can prevent the lateral etching of the bottom of the etching hole, so that the bottom of the etching hole is guided into the central through hole between the ring-shaped spacers, thus the bottom of the etching hole is corrected to the correct position, so that the formed opening structure can normally expose the surface of the target metal layer.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more particularly to an opening structure and a method for forming the same, and a contact plug and a method for forming the same. Background Technology

[0002] As integrated circuits evolve towards very large-scale integrated circuits, the circuit density inside integrated circuits is increasing, and the number of components they contain is also increasing. This development makes it impossible for the wafer surface to provide enough area to fabricate the required interconnects.

[0003] To meet the interconnect requirements of miniaturized components, the design of multilayer metal interconnects with two or more layers has become a common approach in VLSI technology. Currently, the conduction between different metal layers or between a metal layer and a pad layer can be achieved through contact plugs. The formation process of existing contact plugs generally includes: forming a target metal layer in a substrate, the target metal layer being flush with the surface of the substrate; forming a dielectric layer on the substrate and the target metal layer; forming etched vias (or contact windows) in the dielectric layer that expose the surface of the target metal layer; and filling the etched vias (or contact windows) with metal to form a contact plug.

[0004] As the integration of devices increases, the aspect ratio of etched vias formed in the dielectric layer also continues to increase. Creating vias with high aspect ratios has always been a significant challenge for etching processes. When forming vias with high aspect ratios, issues such as via offset, poor hole contact, or over-etching of the hole are common. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the problem of via offset, poor hole contact or over-etching when forming high aspect ratio etched vias.

[0006] This invention provides a method for forming an open structure, characterized by comprising:

[0007] A substrate is provided in which a target layer is formed, the substrate exposing the surface of the target layer;

[0008] An annular gasket is formed on the surface of the target layer, and the annular gasket has a central through hole that exposes a portion of the surface of the target layer.

[0009] A dielectric layer is formed covering the substrate, the target layer, and the annular gasket;

[0010] The dielectric layer is etched to form an etched hole that communicates with a central via in the dielectric layer, and the etched hole and the central via form an open structure.

[0011] Optionally, an etching guide structure is also formed in the central via. When etching the dielectric layer to form an etching hole communicating with the central via, the etching rate of the etching guide structure is greater than the etching rate of the dielectric layer.

[0012] Optionally, the etching guide structure is an air gap structure or a sacrificial layer filling the central through hole, and the top of the etching guide structure is lower than the top surface of the annular gasket.

[0013] Optionally, the formation process of the air gap structure is as follows: when forming the medium layer through chemical vapor deposition, the step coverage of the deposition process is adjusted so that the formed medium layer seals the opening structure of the central through hole, thereby forming the air gap structure.

[0014] Optionally, the material of the sacrificial layer is different from that of the dielectric layer. When etching the dielectric layer to form an etched hole communicating with the central via, the etching rate of the sacrificial layer is greater than that of the dielectric layer.

[0015] Optionally, the material of the annular gasket is different from the material of the dielectric layer. When etching the dielectric layer to form an etched hole communicating with the central through hole, the etching rate of the dielectric layer is greater than the etching rate of the annular gasket.

[0016] Optionally, the process of forming the annular gasket includes: forming a mask material layer on the surface of the substrate and the target layer portion, wherein a through hole is formed in the mask material layer to expose the surface of the target layer portion; forming a gasket material layer on the sidewall and bottom surfaces of the through hole and on the surface of the mask material layer; removing the gasket material layer on the surface of the mask material layer and the bottom surface of the through hole without mask etching; forming an annular gasket on the sidewall surface of the through hole, wherein the annular gasket has a central through hole; and removing the mask material layer.

[0017] Optionally, the annular gasket may be circular, elliptical, or rectangular.

[0018] Optionally, the inner diameter of the annular gasket is greater than or equal to the diameter of the etched hole.

[0019] Optionally, one of the etched holes is connected to a corresponding central through hole, or one of the etched holes is connected to multiple corresponding central through holes, and multiple etched holes are connected to a corresponding central through hole.

[0020] The present invention also provides a method for forming a contact plug, comprising:

[0021] An opening structure is formed using the aforementioned method, and the opening structure is used as a contact window structure.

[0022] Conductive material is formed in the contact window structure to form a contact plug.

[0023] The present invention also provides an opening structure, comprising:

[0024] A substrate in which a target layer is formed, the substrate exposing the surface of the target layer;

[0025] An annular gasket located on the surface of the target layer, the annular gasket having a central through hole that exposes a portion of the surface of the target layer;

[0026] A dielectric layer covering the substrate, target layer, and annular gasket;

[0027] An etched hole located in the dielectric layer and communicating with the central via.

[0028] Optionally, the material of the annular gasket is different from the material of the dielectric layer.

[0029] Optionally, the inner diameter of the annular gasket is greater than or equal to the diameter of the etched hole.

[0030] The present invention also provides a contact plug, comprising:

[0031] A substrate in which a target layer is formed, the substrate exposing the surface of the target layer;

[0032] An annular gasket located on the surface of the target layer, the annular gasket having a central through hole that exposes a portion of the surface of the target layer;

[0033] A dielectric layer covering the substrate, target layer, and annular gasket;

[0034] An etched hole located in the dielectric layer and communicating with the central via;

[0035] Contact plugs located in the etched holes and the central through hole.

[0036] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0037] The present invention discloses a method for forming an opening structure, comprising: providing a substrate in which a target layer is formed, the substrate exposing the surface of the target layer; forming an annular gasket on the surface of the target layer, the annular gasket having a central through-hole exposing a portion of the surface of the target layer; forming a dielectric layer covering the substrate, the target layer, and the annular gasket; etching the dielectric layer to form an etched hole communicating with the central through-hole, the etched hole and the central through-hole constituting the opening structure. By forming the annular gasket, when the etched hole is formed in the dielectric layer, if the etched hole is bent or misaligned, the annular gasket can prevent lateral etching of the bottom of the etched hole, guiding the bottom of the etched hole into the central through-hole between the annular gaskets, thereby correcting the bottom of the etched hole to the correct position, allowing the formed opening structure to properly expose the surface of the target metal layer. Furthermore, the presence of the annular gasket can prevent abnormalities such as leakage caused by metal diffusion due to the formation of contact plugs in the subsequent opening structure.

[0038] Furthermore, by forming an etching guide structure in the central through-hole of the annular gasket, during the subsequent etching of the dielectric layer to form an etched hole, the etching guide structure has a higher etching rate than the dielectric layer, making it easier for the bottom of the through-hole to move towards the etching guide structure. This guides the bottom of the etched hole into the central through-hole. The etching guide structure also allows the formed opening structure to quickly reach the target layer, shortening the overall etching time for forming the opening structure. It also simplifies the complexity of the etching process for the opening structure, optimizes the etching process for the opening structure, and prevents over-etching of the target layer. Furthermore, when there are alignment misalignment or bending issues in the etched holes, the etching rate of the etching guide structure is greater than that of the dielectric layer. This allows the etching plasma gas to be correctly guided towards the central via. As a result, the bottom of the etched hole with alignment misalignment or bending can be guided more accurately and quickly into the central via through the etching guide structure, achieving the effect of straightening the bend. This prevents the problem of the formed opening structure failing to properly expose the surface of the target layer.

[0039] Furthermore, the formation process of the annular gasket includes: forming a mask material layer on the surface of the substrate and the target layer portion, wherein a through-hole is formed in the mask material layer to expose the surface of the target layer portion; forming a gasket material layer on the sidewall and bottom surfaces of the through-hole and on the surface of the mask material layer; removing the gasket material layer from the surface of the mask material layer and the bottom surface of the through-hole using maskless etching, and forming an annular gasket on the sidewall surface of the through-hole. The annular gasket formed by this method has high dimensional and shape accuracy and a high-precision sidewall morphology.

[0040] Furthermore, the etching guide structure is an air gap structure, and the air gap structure is composed of air. Therefore, when the etching medium layer is subsequently etched to form an etching hole, the bottom of the etching hole can be more easily guided into the central through hole.

[0041] Furthermore, the etching guide structure is a sacrificial layer that fills the central via. The material of the sacrificial layer is different from the material of the dielectric layer that is subsequently formed. When etching the dielectric layer to form an etching hole, the etching rate of the sacrificial layer is greater than the etching rate of the dielectric layer. Therefore, when etching the dielectric layer to form an etching hole, it is easier to guide the bottom of the etching hole into the central via.

[0042] In the opening structure of the present invention, when forming an etched hole in the dielectric layer using an annular gasket, if the etched hole is bent or misaligned, the annular gasket can prevent lateral etching of the bottom of the etched hole, so that the bottom of the etched hole is guided into the central through hole between the annular gaskets, thereby correcting the bottom of the etched hole to the correct position, so that the formed opening structure can properly expose the surface of the target metal layer. In addition, the presence of the annular gasket can prevent abnormalities such as leakage caused by metal diffusion due to the formation of contact plugs in the subsequent opening structure.

[0043] The contact plug and its forming method of the present invention, when forming an etched hole in a dielectric layer using an annular gasket, prevents lateral etching of the bottom of the etched hole when the etched hole is bent or misaligned. This guides the bottom of the etched hole to the central through-hole between the annular gaskets, thereby correcting the bottom of the etched hole to the correct position. This allows the formed opening structure to properly expose the surface of the target metal layer, and enables the contact plug formed in the opening structure to properly connect with the target metal layer. Furthermore, the presence of the annular gasket prevents metal diffusion caused by the subsequent formation of the contact plug in the opening structure, which could lead to abnormalities such as leakage. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the existing through-hole structure;

[0045] Figures 2-14 This is a cross-sectional structural schematic diagram of the formation process of the opening structure in an embodiment of the present invention;

[0046] Figure 15 This is a cross-sectional structural diagram of the contact plug formation process according to an embodiment of the present invention. Detailed Implementation

[0047] As mentioned in the background section, there is often a via offset problem when forming etched vias with high aspect ratios.

[0048] Research has found that, reference Figure 1Because the magnetic field bias at the wafer edge is relatively weak, the etched via 104 is prone to bending, causing the bottom of the etched via to deviate from its normal position, thus failing to properly expose the target metal layer surface. Alternatively, deviations in the overlay process may cause the formed etched via to deviate from its normal position.

[0049] To address this, the present invention provides an opening structure and its forming method, as well as a contact plug and its forming method. The method for forming the opening structure includes providing a substrate in which a target layer is formed, the substrate exposing the surface of the target layer; forming an annular gasket on the surface of the target layer, the annular gasket having a central through-hole exposing a portion of the target layer surface; forming a dielectric layer covering the substrate, the target layer, and the annular gasket; etching the dielectric layer to form an etched hole communicating with the central through-hole, the etched hole and the central through-hole constituting the opening structure. By forming the annular gasket, when the etched hole is formed in the dielectric layer, if the etched hole is bent or misaligned, the annular gasket can prevent lateral etching of the bottom of the etched hole, guiding the bottom of the etched hole into the central through-hole between the annular gaskets. This corrects the bottom of the etched hole to the correct position, allowing the formed opening structure to properly expose the target metal layer surface. Furthermore, the presence of the annular gasket prevents metal diffusion and abnormalities such as leakage caused by the subsequent formation of the contact plug in the opening structure.

[0050] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the detailed description of the embodiments of the present invention, for ease of explanation, the schematic diagrams may be partially enlarged without adhering to general proportions, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0051] refer to Figure 2 A substrate 201 is provided, wherein a target layer 202 is formed in the substrate 201, and the surface of the target layer 202 is exposed in the substrate 201.

[0052] In one embodiment, the substrate 201 may be a semiconductor substrate, and the target layer 202 may be a doped region (e.g., a region doped with N-type or P-type impurity ions) or a metal silicide region (e.g., a nickel silicide region or a cobalt silicide region) located in the semiconductor substrate. The semiconductor substrate may be made of silicon (Si), germanium (Ge), or silicon-germanium (GeSi), silicon carbide (SiC); it may also be silicon-on-insulator (SOI), germanium-on-insulator (GOI); or it may be other materials, such as gallium arsenide or other group III-V compounds.

[0053] In other embodiments, the substrate 201 may include a semiconductor substrate and an interlayer dielectric layer located within the semiconductor substrate, with the target layer 202 located within the interlayer dielectric layer. The interlayer dielectric layer may be a single-layer or multi-layer stacked structure, and the target layer 202 may be a metal layer, which may be connected to a conductive structure (such as a conductive plug) formed in the underlying dielectric layer.

[0054] The surface of the target layer 202 may be flush with the surface of the substrate 201 or slightly higher than the surface of the substrate 102.

[0055] The substrate 201 may form one or more (≥2) target layers 202. When there are multiple target layers 202, adjacent target layers are separate. In this embodiment, only one target layer 202 in the substrate 201 is used as an example for illustration.

[0056] An annular gasket needs to be subsequently formed on the target layer 202. In one embodiment, referring to... Figure 2 A mask material layer 206 is formed on the partial surfaces of the substrate 201 and the target layer 202, and through holes 207 are formed in the mask material layer 206 to expose the partial surface of the target layer 202.

[0057] The mask material layer 206 can be made of one or more of the following: photoresist, silicon nitride, silicon oxide, silicon carbonitride, silicon oxynitride, polycrystalline silicon, amorphous silicon, amorphous carbon, and low-k dielectric materials. The mask material layer 206 can be formed using a chemical vapor deposition process.

[0058] In one embodiment, the mask material layer 206 is made of photoresist, and through-holes 207 are formed in the mask material layer 206 through exposure and development processes. When the mask material layer 206 is made of other materials, through-holes 207 can be formed in the mask material layer 206 through etching processes.

[0059] The shape and position of the through hole 207 define the shape and position of the subsequently formed annular gasket.

[0060] refer to Figure 3 A gasket material layer 208 is formed on the sidewall and bottom surface of the through hole 207 and on the surface of the mask material layer 206.

[0061] The gasket material layer 208 is subsequently used to form an annular gasket. The material of the gasket material layer 208 is different from the material of the subsequently formed dielectric layer. When etching holes are subsequently formed in the dielectric layer, the dielectric layer has a high etching selectivity relative to the annular gasket. This allows the annular structure to effectively prevent lateral etching when the dielectric layer is etched to form a through-hole, and to more effectively guide the bottom of the etching hole into the central through-hole.

[0062] The material of the annular gasket material layer 208 can be one or more of silicon nitride, silicon oxide, silicon carbonitride, and silicon oxynitride. In this embodiment, the material of the annular gasket material layer 208 is silicon nitride, and the annular gasket material layer is formed by chemical vapor deposition.

[0063] The thickness of the gasket material layer 208 determines the width of the subsequently formed annular gasket. In one embodiment, the thickness of the gasket material layer 208 is 5 nm-5 μm.

[0064] refer to Figure 4 The mask material layer 206 and the gasket material layer on the bottom surface of the through hole are removed by maskless etching, and an annular gasket 203 is formed on the side wall surface of the through hole, and a central through hole 213 is formed in the middle of the annular gasket 203.

[0065] By forming an annular gasket 203, when etching holes are subsequently formed in the dielectric layer, if the etching holes are bent or misaligned, the annular gasket can prevent lateral etching at the bottom of the etching holes, so that the bottom of the etching holes is guided into the central through hole between the annular gaskets. Thus, the bottom of the etching holes is corrected to the correct position, and the formed opening structure can properly expose the surface of the target metal layer. In addition, the presence of the annular gasket can prevent abnormalities such as leakage caused by metal diffusion due to the formation of contact plugs in the subsequent opening structure.

[0066] The gasket material layer is etched using an anisotropic dry etching process, which can be a plasma etching process.

[0067] refer to Figure 5 After forming the annular gasket 203, the mask material layer 206 is removed. The removal of the mask material layer 206 can be performed using a wet or dry etching process.

[0068] refer to Figure 6 and Figure 7 , Figure 6 and Figure 7 This is a top view schematic diagram of the aforementioned annular gasket 203. Figure 6 The annular gasket 203 shown is circular in shape. Figure 7 The annular gasket 203 shown is elliptical in shape. In other embodiments, the annular gasket 203 may also be rectangular. The inner diameter of the annular gasket 203 may be greater than or equal to the diameter of the etched hole formed in the subsequent dielectric layer, making it easier to guide the bottom of the etched hole into the central through-hole in the annular gasket 203 when the etched hole is curved. In other embodiments, the outer diameter of the annular gasket may be smaller than the diameter of the etched hole formed in the subsequent dielectric layer.

[0069] In another embodiment, reference Figure 8 When the mask material layer 206 is an isolation material that can be used for electrical isolation between devices, such as when the mask material layer is made of the same material as the dielectric layer subsequently formed, the mask material layer 206 is retained after the annular gasket 203 is formed, and the dielectric layer is then formed directly on the mask material layer 206, thus eliminating the need for additional steps to remove the mask material layer 206.

[0070] refer to Figure 9 An etching guide structure 214 is formed in the central through-hole; a dielectric layer 211 is formed covering the substrate 201, the target layer 202, the annular gasket 203 and the etching guide structure 214.

[0071] By forming an etching guide structure 214 in the central through-hole of the annular gasket 203, during the subsequent etching of the dielectric layer 211 to form an etched hole, the etching rate of the etching guide structure 214 is greater than that of the dielectric layer. Therefore, the bottom of the through-hole is more likely to move towards the etching guide structure 214, guiding the bottom of the etched hole into the central through-hole. Furthermore, the etching guide structure enables the formed opening structure to quickly reach the target layer, shortening the overall etching time for forming the opening structure and simplifying the complexity of the etching process. This optimizes the etching process for the opening structure and prevents over-etching of the target layer. Furthermore, when there are alignment misalignment or bending issues in the etched holes, the etching rate of the etching guide structure 214 is greater than that of the dielectric layer, which can correctly guide the etching plasma gas to move towards the central via. Thus, the bottom of the etched hole with alignment misalignment or bending can be guided to the central via more accurately and faster through the etching guide structure, achieving the effect of straightening the bend. This can prevent the problem that the formed opening structure cannot properly expose the surface of the target layer.

[0072] In this embodiment, the etching guide structure 214 is an air gap structure. The top of the etching guide structure is lower than the top surface of the annular gasket. The air gap structure is composed of air. Therefore, when the etching medium layer is subsequently etched to form an etching hole, the bottom of the etching hole can be more easily guided into the central through hole.

[0073] In one embodiment, the air gap structure is formed when the medium layer 211 is formed. In a specific embodiment, the air gap structure is formed as follows: when the medium layer is formed by chemical vapor deposition, the step coverage of the deposition process is adjusted so that the formed medium layer 211 seals the top opening of the central through hole, thereby forming the air gap structure (214).

[0074] refer to Figure 10 The dielectric layer 211 is etched to form an etched hole 215 communicating with the central via 213. The etched hole 215 and the central via 213 form an open structure. During the process of etching the dielectric layer 211 to form the etched hole 215, the etching guide structure 214 (see reference) Figure 9 It is used to guide the bottom of the etched hole 215 into the central through hole 213.

[0075] During the etching of the dielectric layer 211, when the bottom of the formed etching hole 215 is connected to the air gap structure, the dielectric layer on the sidewall and bottom of the central through hole 213 is etched away (when the air gap structure is formed, part of the dielectric layer will also be formed on the sidewall and bottom of the central through hole 213).

[0076] In one embodiment, when etching the dielectric layer 211, if the formed etched hole 215 is bent, refer to Figure 11 The method of this application can guide the curved etched hole 215 to connect with the central through hole 213.

[0077] It should be noted that in the foregoing embodiments, a single etched hole 215 and a central through hole 213 are used as examples for illustration. In other embodiments, there may be multiple etched holes 215 and central through holes 213. One etched hole may be connected to a corresponding central through hole, or one etched hole may be connected to multiple corresponding central through holes, and multiple etched holes may be connected to a corresponding central through hole.

[0078] In another embodiment of the invention, reference Figure 12 The etching guide structure 214 is a sacrificial layer that fills the central via.

[0079] The material of the sacrificial layer is different from that of the subsequently formed dielectric layer. When etching the dielectric layer to form an etch hole, the etching rate of the sacrificial layer is greater than that of the dielectric layer. Therefore, when etching the dielectric layer to form an etch hole, it is easier to guide the bottom of the etch hole into the central via.

[0080] In one embodiment, the material of the sacrificial layer may be one of silicon nitride, silicon oxide, silicon carbonitride, silicon oxynitride, amorphous carbon, polyimide, or ultra-low k material.

[0081] In one embodiment, when forming the sacrificial layer, a second void structure is formed in the sacrificial layer, which allows for a faster rate when etching the etching guide structure, resulting in a faster etching rate and efficiency when forming the opening, and helps to prevent over-etching of the target layer.

[0082] The surface of the sacrificial layer (214) can be lower than or flush with the top surface of the annular gasket 203 to maintain a good final morphology. If the surface of the sacrificial layer (214) is higher than the top surface of the annular gasket 203, it will cause damage to the outer dielectric layer 211 of the annular gasket 203. In the subsequent metal filling process, the metal may be filled into the dielectric layer, resulting in leakage.

[0083] refer to Figure 13 A dielectric layer 211 is formed covering the substrate 201, the target layer 202, the annular gasket 203, and the etch guide structure (sacrificial layer) 214.

[0084] refer to Figure 14 The dielectric layer 211 is etched to form an etched hole 215 communicating with the central through hole 213. The etched hole 215 and the central through hole 213 form an open structure. During the process of etching the dielectric layer 211 to form the etched hole 215, the etching guiding structure (sacrificial layer) 214 is used to guide the bottom of the etched hole 215 into the central through hole 213.

[0085] Figure 14 The etched hole 215 shown is an etched hole with overprinting misalignment. The method of this application can guide the etched hole 215 with overprinting misalignment to connect with the central through hole 213. In other embodiments, the etched hole is an etched hole without overprinting misalignment.

[0086] In one embodiment, after forming the aforementioned opening structure, metal is filled into the opening structure to form a contact plug.

[0087] An embodiment of the present invention also provides a method for forming a contact plug, see reference. Figure 15 ,

[0088] An opening structure is formed using the aforementioned method, and the opening structure is used as a contact window structure.

[0089] Conductive material is formed in the contact window structure to form a contact plug 216.

[0090] The conductive material can be a metal or doped polycrystalline silicon.

[0091] It should be noted that the limitations or descriptions of similar or identical structures in this embodiment (the method of forming the contact plug) and the foregoing embodiment (the process of forming the opening structure) are not limited in this embodiment. Please refer to the limitations or descriptions in the corresponding parts of the foregoing embodiments for details.

[0092] An embodiment of the present invention also provides an opening structure, see reference. Figure 10 , Figure 11or Figure 14 ,include:

[0093] A substrate 201, wherein a target layer 202 is formed therein, and the surface of the target layer 202 is exposed in the substrate 201;

[0094] An annular gasket 203 is located on the surface of the target layer 202, and the annular gasket 203 has a central through hole 213 that exposes a portion of the surface of the target layer 202.

[0095] A dielectric layer 211 covering the substrate 201, the target layer 202, and the annular gasket 203;

[0096] An etched hole 215 is located in the dielectric layer 211 and communicates with the central through hole 213.

[0097] In one embodiment, the material of the annular gasket 203 is different from the material of the dielectric layer 211.

[0098] In one embodiment, the inner diameter of the annular gasket 203 is greater than or equal to the diameter of the etched hole 215.

[0099] It should be noted that the limitations or descriptions of similar or identical structures in this embodiment (opening structure) and the aforementioned embodiments (forming process of opening structure) are not limited in this embodiment. Please refer to the limitations or descriptions in the corresponding parts of the aforementioned embodiments for details.

[0100] One embodiment of the present invention also provides a contact plug, see reference. Figure 15 ,include:

[0101] A substrate 201, wherein a target layer 202 is formed therein, and the surface of the target layer 202 is exposed in the substrate 201;

[0102] An annular gasket 203 is located on the surface of the target layer 202, and the annular gasket 203 has a central through hole 213 in the middle that exposes a portion of the surface of the target layer 202 (see reference). Figure 11 );

[0103] A dielectric layer 211 covering the substrate 201, the target layer 202, and the annular gasket 203;

[0104] The etched hole 215 (reference) is located in the dielectric layer 211 and communicates with the central via 213. Figure 11 );

[0105] Contact plug 216 located in the etched hole and the central through hole.

[0106] It should be noted that the limitations or descriptions of similar or identical structures in this embodiment (open contact plug) and the aforementioned embodiments (formation process of opening structure) are not limited in this embodiment. Please refer to the limitations or descriptions in the corresponding parts of the aforementioned embodiments for details.

[0107] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for forming an open structure, characterized in that, include: A substrate is provided in which a target layer is formed, the substrate exposing the surface of the target layer; An annular gasket is formed on the surface of the target layer, and the annular gasket has a central through hole that exposes a portion of the surface of the target layer. A dielectric layer is formed covering the substrate, the target layer, and the annular gasket; The dielectric layer is etched to form an etched hole communicating with a central via in the dielectric layer, and the etched hole and the central via form an open structure; The process of forming the annular gasket includes: forming a mask material layer on the surface of the substrate and the target layer portion, wherein a through hole is formed in the mask material layer to expose the surface of the target layer portion; forming a gasket material layer on the sidewall and bottom surfaces of the through hole and on the surface of the mask material layer; removing the gasket material layer on the surface of the mask material layer and the bottom surface of the through hole without mask etching; forming an annular gasket on the sidewall surface of the through hole, wherein the annular gasket has a central through hole; and removing the mask material layer.

2. The method for forming the opening structure as described in claim 1, characterized in that, An etching guide structure is also formed in the central via. When etching the dielectric layer to form an etching hole that communicates with the central via, the etching rate of the etching guide structure is greater than the etching rate of the dielectric layer.

3. The method for forming the opening structure as described in claim 2, characterized in that, The etching guide structure is an air gap structure or a sacrificial layer that fills the central through hole, and the top of the etching guide structure is lower than the top surface of the annular gasket.

4. The method for forming the opening structure as described in claim 3, characterized in that, The formation process of the air gap structure is as follows: when the medium layer is formed by chemical vapor deposition, the step coverage of the deposition process is adjusted so that the formed medium layer seals the opening structure of the central through hole, thereby forming the air gap structure.

5. The method for forming the opening structure as described in claim 3, characterized in that, The material of the sacrificial layer is different from that of the dielectric layer. When etching the dielectric layer to form an etched hole communicating with the central via, the etching rate of the sacrificial layer is greater than that of the dielectric layer.

6. The method for forming the opening structure as described in claim 1, characterized in that, The material of the annular gasket is different from that of the dielectric layer. When etching the dielectric layer to form an etched hole communicating with the central through hole, the etching rate of the dielectric layer is greater than that of the annular gasket.

7. The method for forming the opening structure as described in claim 1, characterized in that, The annular gasket can be circular, elliptical, or rectangular.

8. The method for forming the opening structure as described in claim 1, characterized in that, The inner diameter of the annular gasket is greater than or equal to the diameter of the etched hole.

9. The method for forming the opening structure as described in claim 1, characterized in that, One of the etched holes is connected to a corresponding central through hole, or one of the etched holes is connected to multiple corresponding central through holes, and multiple etched holes are connected to a corresponding central through hole.

10. A method for forming a contact plug, characterized in that, include: An opening structure is formed by means of any one of claims 1-9, and the opening structure is used as a contact window structure; Conductive material is formed in the contact window structure to form a contact plug.

11. An open structure, characterized in that, include: A substrate in which a target layer is formed, the substrate exposing the surface of the target layer; An annular gasket located on the surface of the target layer, the annular gasket having a central through hole that exposes a portion of the surface of the target layer; A dielectric layer covering the substrate, target layer, and annular gasket; An etched hole located in the dielectric layer and communicating with the central via is provided, wherein the etched hole and the central via form an open structure.

12. The opening structure as described in claim 11, characterized in that, The material of the annular gasket is different from the material of the dielectric layer.

13. The opening structure as described in claim 11, characterized in that, The inner diameter of the annular gasket is greater than or equal to the diameter of the etched hole.

14. A contact plug, characterized in that, include: A substrate in which a target layer is formed, the substrate exposing the surface of the target layer; An annular gasket located on the surface of the target layer, the annular gasket having a central through hole that exposes a portion of the surface of the target layer; A dielectric layer covering the substrate, target layer, and annular gasket; An etched hole located in the dielectric layer and communicating with the central via; Contact plugs located in the etched holes and the central through hole.

Images