Forming method of metal interconnection structure and metal interconnection structure
By pre-depositing a protective layer on the sidewalls and bottom of the trench before etching, the etching energy is absorbed, the trench structure is prevented from being damaged, the problems of etching through and over-etching are solved, and the production yield of the metal interconnect structure is improved.
Patent Information
- Application Number
- CN202510884098.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-28
- Publication Date
- 2025-10-10
AI Technical Summary
During the metal interconnect etching process, the etching energy impact causes the trench structure to be destroyed, resulting in etching through and over-etching, exposing the metal material and causing short circuit problems, affecting the yield.
A protective layer is pre-deposited before etching. Carbon-containing gas and inert gas react in a plasma environment to generate a polymer to form a protective layer that covers the sidewalls and bottom of the trench, absorbs etching energy, and prevents damage to the trench structure.
Effectively prevent etching through and over-etching, protect the integrity of the trench structure, improve production yield, and reduce short circuit problems.
Smart Images
Figure CN120767253A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a method for forming a metal interconnection structure and a metal interconnection structure. Background Art
[0002] In the metal interconnect etching process, after the main etching forms the basic trench structure, it is necessary to continue etching the contact holes for metal interconnection. During the etching process, due to the impact of etching energy, the trench structure used to fill the metal material is prone to etching through and over-etching. The trench structure is damaged, and the metal material is easily exposed, causing short circuit problems, which greatly increases the yield problem caused by short circuits. At present, the main solution to similar problems of this type is to use a verified and standardized optimal production path to manage product production and circulation before the new conditions are put online in the short term to ensure quality and stability. However, this method does not effectively solve the problem from the root, so a new solution needs to be found. Summary of the Invention
[0003] The purpose of the present invention is to provide a method for forming a metal interconnect structure and a metal interconnect structure to solve the yield problem that, during the process of etching contact holes, the trench structure adjacent to the etched hole is destroyed due to unexpected etching, exposing the metal material filled therein, generating unnecessary electrical connections and causing short circuits.
[0004] To solve the above technical problems, the present invention provides a method for forming a metal interconnect structure, comprising the following steps:
[0005] providing a first dielectric layer, and forming a first metal layer in the first dielectric layer;
[0006] forming a barrier layer, wherein the barrier layer covers the first dielectric layer;
[0007] Etching the barrier layer to form a first trench for filling a metal material to form a second metal layer;
[0008] forming a second dielectric layer, wherein the second dielectric layer covers the barrier layer;
[0009] Etching the second dielectric layer to form a second trench, wherein the first metal layer falls within a projection range of the second trench on the first dielectric layer, the second trench is used to be filled with a metal material to form a third metal layer, and the second trench is adjacent to the first trench in a horizontal direction;
[0010] forming a protection layer, the protection layer covering the bottom and sidewalls of the second trench; and
[0011] The protection layer and the barrier layer at the bottom of the second trench are sequentially etched to form a contact hole penetrating the barrier layer.
[0012] Optionally, the protective layer is generated by plasma reaction of a mixture of carbon-containing gas and inert gas.
[0013] Optionally, the carbon-containing gas includes methane.
[0014] Optionally, the inert gas includes argon.
[0015] Optionally, the second dielectric layer includes a first sub-dielectric layer, an etch stop layer, and a second sub-dielectric layer stacked in sequence from bottom to top.
[0016] Optionally, the material of the etch stop layer includes silicon nitride.
[0017] Optionally, the material of the barrier layer includes nitrogen-doped silicon carbide.
[0018] Optionally, the formation process of the first dielectric layer and the sub-dielectric layer includes a plasma enhanced chemical vapor deposition process, and a silicon source including tetraethoxysilane is used as a reaction gas.
[0019] Optionally, the method of etching the barrier layer includes dry etching.
[0020] The present invention also provides a metal interconnect structure, which is formed using any of the above methods.
[0021] In summary, the present invention provides a method for forming a metal interconnect structure and a metal interconnect structure, which prevents the trench structure used to fill the metal material near the contact hole from being etched through and over-etched during the process of etching the contact hole by pre-depositing a protective layer, thereby preventing the metal material from being exposed, thereby causing a short circuit problem and affecting the yield. After the trench structure is etched, a carbon-containing gas and an inert gas are introduced into the reaction chamber, so that the mixed gas reacts in a plasma environment to generate a polymer that adheres to the sidewalls and bottom of the trench, forming a protective layer. In the process of etching the contact hole, the protective layer can absorb the etching energy, prevent the trench structure from being etched through and over-etched, protect the physical structure of the trench from being damaged, and obtain the expected structure with uniform specifications, which can effectively avoid the short circuit problem caused by etching through and over-etching, and improve the production yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 is a flow chart of a method for forming a metal interconnect structure provided by an embodiment of the present invention;
[0023] Figures 2 to 5 for Figure 1 Structural schematic diagram of the metal interconnection structure corresponding to each step;
[0024] Figure 62. It is a structural schematic diagram of the etching punch-through phenomenon that occurs when etching a contact hole trench structure without forming a protective layer in an embodiment of the present invention;
[0025] Figure 7 2 is a schematic diagram of a structure for forming a protective layer and etching a contact hole in an embodiment of the present invention;
[0026] The descriptions of the reference numerals are as follows:
[0027] 11-first dielectric layer; 12-second dielectric layer; 13-third dielectric layer; 2-first metal layer; 3-barrier layer;
[0028] 4 - first groove; 5 - etch stop layer; 6 - anti-reflective coating; 7 - photoresist layer; 8 - second trench; 9 - protective layer; 100 - baffle; 110 - etching energy. DETAILED DESCRIPTION
[0029] The following describes in further detail the method for forming a metal interconnect structure and the metal interconnect structure proposed in the present invention, in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention. Furthermore, the structures depicted in the drawings are often portions of actual structures. In particular, different drawings may require different emphases and may use different scales. It should be understood that relative terms such as "above," "below," "top," and "bottom" in the drawings may be used to describe the relationships of various elements to one another. These relative terms are intended to encompass different orientations of elements other than those depicted in the drawings. For example, if a device is inverted relative to the view in the drawings, an element described as "above" another element would now be below that element. It should also be understood that, unless otherwise specified or indicated, the terms "first," "second," and "third," etc., used in this specification are intended solely to distinguish between components, elements, steps, and the like, and are not intended to indicate a logical or sequential relationship between the components, elements, steps, and the like.
[0030] refer to Figure 1 As shown, an embodiment of the present invention provides a method for forming a metal interconnect structure, comprising the following steps:
[0031] S1, providing a first dielectric layer, and forming a first metal layer in the first dielectric layer;
[0032] S2, forming a barrier layer, wherein the barrier layer covers the first dielectric layer;
[0033] S3, etching the barrier layer to form a first trench for filling a metal material to form a second metal layer;
[0034] S4, forming a second dielectric layer, wherein the second dielectric layer covers the barrier layer;
[0035] S5, etching the second dielectric layer to form a second trench, wherein the first metal layer falls within a projection range of the second trench on the first dielectric layer, the second trench is used to be filled with a metal material to form a third metal layer, and the second trench partially overlaps with the first trench in a height direction;
[0036] S6, forming a protection layer, wherein the protection layer covers the bottom and sidewalls of the second trench; and
[0037] The protection layer and the barrier layer at the bottom of the second trench are sequentially etched to form a contact hole penetrating the barrier layer.
[0038] By utilizing the method provided by the present invention, the metal interconnect structure formed has a protective layer, which can protect the trench structure adjacent to the etched hole from being damaged during the process of etching the contact hole, thereby avoiding exposure of the metal material filled inside the trench structure due to damage, and preventing unnecessary electrical connections from causing short circuits, thereby greatly improving the production yield.
[0039] The following is combined with Figures 2 to 5 The formation method of the metal interconnection structure proposed in this embodiment is further described.
[0040] refer to Figure 2 As shown, step S1 is performed to provide a first dielectric layer 11 , and a first metal layer 2 is formed by etching the first dielectric layer 11 and filling the first dielectric layer 11 with metal material.
[0041] refer to Figure 3 As shown, step S2 is performed to form a barrier layer 3 on the first dielectric layer 11, the barrier layer 3 covers the first dielectric layer 11, and a first trench 4 is obtained by etching the barrier layer 3. The first trench 4 is used to fill a metal material to form a second metal layer.
[0042] refer to Figure 4 As shown, step S3 is performed to sequentially deposit a second dielectric layer 12, an etch stop layer 5, and a third dielectric layer 13 on the barrier layer 3, deposit an anti-reflective coating 6 on the third dielectric layer 13, and apply a photoresist layer 7. The pattern is transferred to the second dielectric layer 12, the etch stop layer 5, the third dielectric layer 13, and the barrier layer 3 through exposure, development, and etching to form a second trench 8.
[0043] refer to Figure 4As shown, step S4 is executed, the projection of the second groove 8 in the height direction covers the first metal layer, and the second groove 8 partially overlaps with the first groove 4 in the height direction in the horizontal direction. It should be noted that the height direction mentioned in this embodiment is the thickness direction of the material layer; and there is a gap between the first groove 4 and the second groove 8 in the horizontal direction, and this area serves as a baffle 100 to separate the first groove 4 from the second groove 8.
[0044] refer to Figure 5 As shown, step S5 is performed to remove the photoresist layer 7 and form a protective layer 9, which covers the bottom and sidewalls of the second trench 8; and
[0045] The protection layer 9 and the barrier layer 3 at the bottom of the second trench 8 are etched in sequence to form a contact hole penetrating the barrier layer 3 .
[0046] In this embodiment, as a preference, the first dielectric layer 11, the second dielectric layer 12 and the third dielectric layer 13 can be deposited using a plasma enhanced chemical vapor deposition (PECVD) process, and can use a gas including tetraethoxysilane (TEOS) as a silicon source. Specifically, the plasma enhanced chemical vapor deposition process can effectively reduce the thermal budget, and can adapt to complex three-dimensional structures with good conformality.
[0047] Furthermore, barrier layer 3 can be made of nitrogen-doped silicon carbide, which provides high etch selectivity, high mechanical strength, thermal stability, and chemical inertness. Etch stop layer 5 can be made of silicon nitride, which provides high etch selectivity and protects underlying structures. Its dense structure can also isolate impurities and effectively block ion diffusion, while also serving as a hard mask.
[0048] In this embodiment, protective layer 9 is preferably formed by introducing a carbon-containing gas into a reaction chamber to react with an inert gas plasma. Methane can be used as the carbon-containing gas, and argon can be used as the inert gas. During the plasma process, methane can passivate dangling bonds on the material surface, introduce carbon, and adjust film properties. Argon can act as a carrier gas to carry the reactive gases into the reaction chamber, regulating plasma activity and suppressing side reactions.
[0049] In the reaction chamber, methane and argon react at the bottom and sidewalls of the second groove 8 to generate a polymer attached to its surface, forming a protective layer 9. Specifically, argon dissociates into argon ions and electrons under the action of the radio frequency electric field in the reaction chamber, and the argon ions are further accelerated by the radio frequency electric field to form high-energy particles. Methane gas provides a carbon source, and the accelerated argon ions collide with methane molecules. The carbon-hydrogen bonds of the methane molecules are broken after being hit by the argon ions, forming active carbon-based free radicals such as -CH3 and =CH2, as well as hydrogen free radicals. At the same time, the argon ions also physically collide with the bottom and sidewalls of the second groove 8, breaking the chemical bonds on the surface of the material and enhancing the surface active sites. The free radicals generated by the dissociation of methane molecules react at the active sites on the bottom and sidewalls of the second groove 8 to generate carbon-containing polymers, which cover its surface to form a protective layer 9.
[0050] It should be noted that the ratio of methane and argon in this embodiment needs to be controlled within a certain range. A high methane input flow rate can lead to excessive deposition of the protective layer 9, thereby blocking the image, while a low methane flow rate can result in insufficient reactants and incomplete coverage of the protective layer 9. The argon input flow rate regulates the ion activity in the plasma environment, thereby affecting the ion bombardment intensity and the adhesion density and strength of the protective layer 9. Furthermore, the gas reaction time also needs to be controlled to prevent the reaction time from being too short, resulting in insufficient film thickness of the protective layer 9, or too long, affecting the subsequent etching efficiency.
[0051] In view of this, in this embodiment, as a preference, a plasma enhanced process can be used to form the protective layer 9, and a mixed gas consisting of 10 to 30 sccm of methane and 90 to 110 sccm of argon can be used to react for 2 to 8 seconds to form the protective layer 9.
[0052] In this embodiment, two different metal interconnect structures are compared. The difference between the two metal interconnect structures is whether a protective layer 9 is formed before etching the contact holes. Figure 6 and Figure 7 As shown, when contact holes are etched directly without forming a protective layer 9, the impact of etching energy 110 causes etching through baffle 100, damaging the physical structure of first trench 4. This can easily form unintended electrical connection paths in subsequent steps, significantly increasing yield issues caused by short circuits. However, when contact holes are etched after forming a protective layer 9, the protective layer 9 adheres to the sidewalls and top of baffle 100, forming a dense physical barrier that absorbs most of the ion energy and significantly reduces the impact of high-energy ions directly impacting baffle 100. This effectively prevents damage to first trench 4, reduces high-energy particle sputtering, and prevents over-etching.
[0053] From the above comparison, it can be seen that the method for forming the metal interconnect structure proposed in the present invention can effectively absorb the etching energy 110 by forming the protective layer 9 through pre-deposition, prevent the occurrence of etching penetration and over-etching, protect the physical structure of the groove from being damaged, reduce the occurrence of short circuit problems, and improve production yield.
[0054] In summary, the embodiments of the present invention provide a method for forming a metal interconnect structure and a metal interconnect structure, which, by pre-depositing a protective layer, prevents the trench structure used to fill the metal material near the contact hole from being etched through and over-etched during the process of etching the contact hole, resulting in exposure of the metal material, thereby causing a short circuit problem and affecting the yield. After the trench structure is etched, a carbon-containing gas and an inert gas are introduced into the reaction chamber, so that the mixed gas reacts in a plasma environment to generate a polymer that adheres to the sidewalls and bottom of the trench, forming a protective layer. In the process of etching the contact hole, the protective layer can absorb the etching energy, prevent the trench structure from being etched through and over-etched, protect the physical structure of the trench from being damaged, and obtain the expected structure with uniform specifications, thereby solving the problem of etching through and over-etching of the structure around the contact hole during the process of etching the contact hole, and improving the production yield.
[0055] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.
Claims
1. A method for forming a metal interconnect structure, characterized in that: include: providing a first dielectric layer, and forming a first metal layer in the first dielectric layer; forming a barrier layer, wherein the barrier layer covers the first dielectric layer; Etching the barrier layer to form a first trench for filling a metal material to form a second metal layer; forming a second dielectric layer, wherein the second dielectric layer covers the barrier layer; Etching the second dielectric layer to form a second trench, wherein the first metal layer falls within a projection range of the second trench on the first dielectric layer, the second trench is used to be filled with a metal material to form a third metal layer, and the second trench partially overlaps with the first trench in a height direction; forming a protective layer, wherein the protective layer covers the bottom and sidewalls of the second trench; as well as, The protection layer and the barrier layer at the bottom of the second trench are sequentially etched to form a contact hole penetrating the barrier layer, with a gap between the contact hole and the first trench.
2. The method for forming a metal interconnect structure according to claim 1, wherein: The protective layer is formed by plasma reaction of a mixed gas of carbon-containing gas and inert gas.
3. The method for forming a metal interconnection structure according to claim 2, wherein: The carbon-containing gas includes methane.
4. The method for forming a metal interconnect structure according to claim 2, wherein: The inert gas includes argon.
5. The method for forming a metal interconnect structure according to claim 1, wherein: The second dielectric layer includes a first sub-dielectric layer, an etch stop layer, and a second sub-dielectric layer stacked in sequence from bottom to top.
6. The method for forming a metal interconnection structure according to claim 5, wherein: The material of the etch stop layer includes silicon nitride.
7. The method for forming a metal interconnect structure according to claim 1, wherein: The material of the barrier layer includes nitrogen-doped silicon carbide.
8. The method for forming a metal interconnect structure according to claim 1, wherein: The formation process of the first dielectric layer and the sub-dielectric layer includes a plasma enhanced chemical vapor deposition process, and a silicon source including tetraethoxysilane is used as a reaction gas.
9. The method for forming a metal interconnection structure according to claim 1, wherein: The method of etching the barrier layer includes dry etching.
10. A metal interconnect structure, characterized in that: The metal interconnect structure is formed by the method according to any one of claims 1 to 9.