Metal interconnection structure and forming method thereof
By using a combination of adhesion-promoting layers and high-entropy nitrides or high-entropy alloys in the metal interconnect structure, the difficulties in trench filling and metal diffusion caused by the thickness of traditional barrier layers are solved, achieving efficient metal interconnect structure formation and meeting the process requirements below 40nm.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-04-03
AI Technical Summary
At the 40nm process node, traditional Ta/TaN double barrier layers have problems such as difficulty in trench filling and metal diffusion leading to device failure. Existing improvement solutions, such as atomic layer deposition of TaN or Co intercalation, have defects such as high interface resistance and insufficient thermal stability.
An adhesion-promoting layer is used to form a first diffusion barrier layer and a covering second diffusion barrier layer only on the trench sidewalls. Combined with high-entropy nitride or high-entropy alloy materials, the total thickness is reduced to less than 4 nanometers. Metal interconnect structures are formed through chemical vapor deposition and magnetron sputtering processes.
It achieves process requirements below 40nm, reduces the thickness of the barrier layer in the metal interconnect structure, improves metal wettability, reduces interface stress, avoids metal filling defects, and is compatible with existing production lines without additional photolithography steps.
Smart Images
Figure CN121793754A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit technology, and in particular to a metal interconnect structure and a method for forming the same. Background Technology
[0002] At the 40nm process node, breakthroughs in metal diffusion barrier layers are centered on the formation of ultrathin nitrides and two-dimensional materials using atomic layer deposition (ALD) technology, combined with selective deposition and composite structure design, to reduce resistance while maintaining barrier performance. Currently, Ta / TaN bilayer barrier layers at the 40nm node face the following challenges: Traditional physical vapor deposition (PVD) processes with TaN thicknesses greater than 3nm lead to difficulties in trench filling, while TaN thicknesses less than 2nm result in pinhole defects; copper diffusion through grain boundaries causes device failure; and the barrier layer's contribution to resistance increases (>15%).
[0003] Existing solutions, such as atomic layer deposition of TaN or Co intercalation, still suffer from drawbacks such as high interfacial resistance and insufficient thermal stability. Summary of the Invention
[0004] The purpose of this invention is to provide a metal interconnect structure and a method for forming the same, so as to solve at least one of the problems of trench filling difficulties caused by excessively thick barrier layers and device failure caused by insufficient barrier layer thickness to prevent metal diffusion.
[0005] To address the aforementioned technical problems, the present invention provides a metal interconnect structure, comprising:
[0006] A substrate on which a dielectric layer is formed, and trenches are formed within the dielectric layer;
[0007] An adhesion promoting layer is located only on the sidewall of the trench;
[0008] A first diffusion barrier layer, wherein the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion;
[0009] A second diffusion barrier layer covers the first diffusion barrier layer and is used to support the first diffusion barrier layer and suppress its breakage, as well as to block metal diffusion.
[0010] A metal layer that fills the trench and covers the second diffusion barrier layer.
[0011] Optionally, the adhesion promoting layer is an aminosilane self-assembled monolayer, the first diffusion barrier layer is made of hexagonal boron nitride, the second diffusion barrier layer is made of high-entropy nitride or high-entropy alloy, and the entropy of the second diffusion barrier layer is greater than 1.95R, where R is a gas constant.
[0012] Optionally, the combined thickness of the first diffusion barrier layer and the second diffusion barrier layer is less than 4 nanometers.
[0013] Optionally, the dielectric layer includes a first dielectric layer and a second dielectric layer stacked sequentially, the trench penetrating the second dielectric layer and exposing the top surface of the first dielectric layer, the material of the first dielectric layer being SiCN, and the material of the second dielectric layer being SiOCH.
[0014] Based on the same inventive concept, the present invention also provides a method for forming a metal interconnect structure, comprising:
[0015] A substrate is provided, on which a dielectric layer is formed, and trenches are formed within the dielectric layer;
[0016] An adhesion-promoting layer is formed only on the sidewalls of the trench;
[0017] A first diffusion barrier layer is formed, and the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion.
[0018] A second diffusion barrier layer is formed, which covers the first diffusion barrier layer and serves to support the first diffusion barrier layer and suppress its breakage, as well as to block metal diffusion.
[0019] A metal layer is formed, which fills the trench and covers the second diffusion barrier layer.
[0020] Optionally, an organosilane molecule is spin-coated onto the dielectric layer and the adhesion-promoting layer is formed by selective passivation via vapor injection.
[0021] Optionally, a first diffusion barrier layer is formed using a chemical vapor deposition process, wherein the first diffusion barrier layer grows only in the region modified by the adhesion promoting layer.
[0022] Optionally, a second diffusion barrier layer may be formed using a magnetron sputtering process.
[0023] Optionally, the adhesion promoting layer is an aminosilane self-assembled monolayer, the first diffusion barrier layer is made of hexagonal boron nitride, the second diffusion barrier layer is made of high-entropy nitride or high-entropy alloy, and the entropy of the second diffusion barrier layer is greater than 1.95R, where R is a gas constant.
[0024] Optionally, the combined thickness of the first diffusion barrier layer and the second diffusion barrier layer is less than 4 nanometers.
[0025] In the metal interconnect structure provided by this invention, the adhesion promoting layer is located only on the sidewall of the trench. The adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion, avoiding the deposition of the first diffusion barrier layer at the bottom of the trench and affecting metal filling. The second diffusion barrier layer covers the first diffusion barrier layer, is used to block metal diffusion, and is used to support the first diffusion barrier layer and suppress the cracking of the first diffusion barrier layer. The metal layer fills the trench and covers the second diffusion barrier layer. This invention uses an adhesion promoting layer to reduce the thickness requirement of traditional metal barrier layers, while improving the wettability of the metal. The material of the second diffusion barrier layer is a high-entropy nitride or a high-entropy alloy, which plays a major role in blocking metal diffusion. The total thickness of the first and second diffusion barrier layers is reduced, meeting the process requirements below 40nm node. The lattice matching of the first diffusion barrier layer reduces interface stress and avoids metal filling defects. The vapor phase injection selective passivation process, in which the adhesion promoting layer is formed only on the sidewall of the trench, is compatible with existing production lines and does not require additional photolithography steps. Attached Figure Description
[0026] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:
[0027] Figure 1 This is a schematic diagram of the metal interconnect structure according to an embodiment of the present invention.
[0028] Figure 2 This is a flowchart of a method for forming a metal interconnect structure according to an embodiment of the present invention.
[0029] Figures 3 to 7 This is a schematic diagram of the corresponding steps in the method for forming a metal interconnect structure according to an embodiment of the present invention.
[0030] In the attached image:
[0031] 10-Substrate; 11-First dielectric layer; 12-Second dielectric layer; 12a-Trench; 13-Adhesion promoting layer; 14-First diffusion barrier layer; 15-Second diffusion barrier layer; 16-Metal layer. Detailed Implementation
[0032] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.
[0033] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. Additionally, as used in this invention, the placement of one element on another element generally only indicates a connection, coupling, cooperation, or transmission relationship between the two elements, which can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0034] Figure 1 This is a schematic diagram of the metal interconnect structure according to an embodiment of the present invention. Figure 1 As shown, this embodiment provides a metal interconnect structure, including: a substrate 10, on which a dielectric layer is formed, and a trench 12a is formed within the dielectric layer; an adhesion promoting layer 13, which is located only on the sidewalls of the trench 12a; a first diffusion barrier layer 14, on which the adhesion promoting layer 13 adsorbs the precursor of the first diffusion barrier layer 14 so that the first diffusion barrier layer 14 is formed only on the sidewalls of the trench 12a and is used to block metal diffusion; a second diffusion barrier layer 15, which covers the first diffusion barrier layer 14 and is used to support the first diffusion barrier layer 14 and suppress the first diffusion barrier layer 14 from cracking; and a metal layer 16, which fills the trench.
[0035] Specifically, substrate 10 can be a semiconductor substrate, made of any semiconductor material suitable for semiconductor devices (such as Si, SiC, SiGe, etc.). Substrate 10 can also be various composite substrates such as silicon-on-insulator (SOI) and germanium-silicon-on-insulator. Those skilled in the art will understand that the substrate is not limited in any way, but can be selected according to the actual application. Various device (not limited to semiconductor device) components (not shown in the figure) can be formed in substrate 10. Substrate 10 may also have other layers or components formed thereon, such as: gate structures, contact holes, dielectric layers, metal interconnects, and vias, etc.
[0036] The dielectric layer formed on the substrate 10 comprises a first dielectric layer 11 and a second dielectric layer 12 stacked sequentially. A trench 12a penetrates the second dielectric layer 12, exposing the top surface of the first dielectric layer 11. The material of the first dielectric layer 11 is, for example, SiCN, and the material of the second dielectric layer 12 is, for example, SiOCH. SiOCH is a low-k dielectric layer. The adhesion-promoting layer 13 is, for example, a self-assembled aminosilane monolayer (SAM). The adhesion-promoting layer 13 is formed by selective passivation via vapor injection, such that the adhesion-promoting layer 13 is located only on the sidewalls of the trench 12a. The principle is as follows: First, etching the trench 12a generates uniform hydroxyl groups on the surface of the trench 12a, which are active sites for reaction with SAM molecules. Second, the bottom of the trench is passivated. A chemical reagent called Hexamethyldisilazane (HMDS) is injected into the reaction chamber in gaseous form. Due to the superior directionality and minimal steric hindrance of HMDS molecules, they preferentially react with the hydroxyl groups at the bottom of the high aspect ratio trench 12a upon entering, generating inert -O-Si(CH3)3 groups. These groups are highly stable, preventing subsequent SAM precursors from bonding with them. An APTMS silane solution is spin-coated onto the etched second dielectric layer 12 (SiOCH low-k dielectric) to form a SAM layer. APTMS molecules diffuse into the trench 12a, reacting only with the unpassivated, reactive hydroxyl groups on the trench sidewalls, thus covalently bonding to the trench sidewall surface. The trench bottom is passivated by HMDS and has no reaction sites, therefore SAM molecules are not adsorbed. An adhesion-promoting layer 13 reduces the thickness requirement of the traditional metal barrier layer, adhering to the first diffusion barrier layer 14 and enabling selective regional growth of the first diffusion barrier layer 14.
[0037] The first diffusion barrier layer 14 is hexagonal boron nitride (h-BN). The adhesion promoting layer 13 selectively adsorbs the precursor of the first diffusion barrier layer 14 through functional groups, enabling h-BN to grow only on the trench sidewalls and avoiding bottom deposition from affecting metal filling. The first diffusion barrier layer 14 completely blocks metal diffusion due to its grain boundary-free properties. The thickness of the first diffusion barrier layer 14 is, for example, 0.5 nm to 1 nm. Compared with the prior art, the thickness of the first diffusion barrier layer 14 is reduced, while the wettability of the metal is improved.
[0038] The second diffusion barrier layer 15 is a high-entropy nitride or a high-entropy alloy (MoNbTaWV)N, and the entropy of the second diffusion barrier layer 15 is greater than 1.95R, where R is a gas constant. The second diffusion barrier layer 15 serves to support the first diffusion barrier layer 14 and suppress its breakage, and also to block metal diffusion. The grain boundary energy of the high-entropy nitride or the high-entropy alloy (MoNbTaWV)N is three times higher than that of TaN, resulting in a significant increase in the metal diffusion activation energy. Therefore, the high-entropy nitride or the high-entropy alloy (MoNbTaWV)N effectively blocks metal diffusion.
[0039] Because the adhesion promoting layer 13 reduces the thickness requirement of conventional metal barrier layers, the sum of the thicknesses of the first diffusion barrier layer 14 and the second diffusion barrier layer 15 is less than 4 nanometers.
[0040] The material of the metal layer 16 is, for example, copper.
[0041] Figure 2 This is a flowchart illustrating a method for forming a metal interconnect structure according to an embodiment of the present invention. Figure 2 As shown, this embodiment also provides a method for forming a metal interconnect structure, including:
[0042] Step S10: A substrate is provided, on which a dielectric layer is formed, and trenches are formed within the dielectric layer;
[0043] Step S20: Form an adhesion promoting layer, which is formed only on the sidewalls of the trench;
[0044] Step S30: A first diffusion barrier layer is formed, wherein the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion.
[0045] Step S40: A second diffusion barrier layer is formed, which covers the first diffusion barrier layer and serves to support the first diffusion barrier layer and suppress its breakage, as well as to block metal diffusion.
[0046] Step S50: A metal layer is formed, which fills the trench and covers the second diffusion barrier layer.
[0047] Figures 3 to 7 This is a schematic diagram of the corresponding steps in the method for forming a metal interconnect structure according to an embodiment of the present invention. To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, the following description is provided in conjunction with the appendix to the specification. Figures 3 to 7 Specific embodiments of the present invention will be described in detail below.
[0048] like Figure 3As shown, a substrate 10 is provided. Specifically, substrate 10 can be a semiconductor substrate, made of any semiconductor material suitable for semiconductor devices (such as Si, SiC, SiGe, etc.). Substrate 10 can also be various composite substrates such as silicon-on-insulator (SOI) and germanium-silicon-on-insulator. Those skilled in the art will understand that the substrate is not limited in any way, but can be selected according to the actual application. Various device (not limited to semiconductor device) components (not shown in the figure) can be formed in substrate 10. Substrate 10 may also have other layers or components formed thereon, such as: gate structures, contact holes, dielectric layers, metal interconnects, and vias, etc.
[0049] Please continue to refer to this. Figure 3 The dielectric layer formed on the substrate 10 includes a first dielectric layer 11 and a second dielectric layer 12 stacked sequentially. The material of the first dielectric layer 11 is, for example, SiCN, and the material of the second dielectric layer 12 is, for example, SiOCH. SiOCH is a low-k dielectric layer.
[0050] like Figure 4 As shown, an etching process is performed to form trench 12a. Trench 12a penetrates the second dielectric layer 12 and exposes the top surface of the first dielectric layer 11. Specifically, a patterned photoresist layer is first formed on the second dielectric layer 12, and then the second dielectric layer 12 is etched to form trench 12a using the patterned photoresist layer as a mask.
[0051] like Figure 5As shown, an adhesion-promoting layer 13 is formed, which is formed only on the sidewalls of the trench 12a. Specifically, an organosilane molecule is spin-coated onto the etched second dielectric layer 12 to form the adhesion-promoting layer 13. The organosilane molecule is, for example, an APTMS silane solution. The material of the adhesion-promoting layer 13 is, for example, a self-assembled aminosilane monolayer (SAM). The adhesion-promoting layer 13 is formed only on the sidewalls of the trench using a vapor-phase injection selective passivation method, meaning that the adhesion-promoting layer 13 is only located on the sidewalls of the trench 12a. The principle is as follows: First, etching the trench 12a will generate uniform hydroxyl groups on the surface of the trench 12a, which are active sites for reaction with SAM molecules. Second, the bottom of the trench is passivated. A chemical reagent called Hexamethyldisilazane (HMDS) is injected into the reaction chamber in gaseous form. Due to the good orientation and low steric hindrance of HMDS molecules, it preferentially reacts with the hydroxyl groups at the bottom of the high aspect ratio trench 12a upon entering, generating an inert -O-Si(CH3)3 group. This group is very stable, and subsequent SAM precursors cannot bond with it. An APTMS silane solution is spin-coated onto the etched second dielectric layer 12 (SiOCH low-k dielectric) to form a SAM layer. APTMS molecules diffuse into the trench 12a and can only react with the unpassivated, reactive hydroxyl groups on the trench sidewalls, thus covalently bonding to the trench sidewall surface. More specifically, the structure of APTMS is H2N(CH2)3Si(OCH3)3, with three methoxy groups (-OCH3) and one aminopropyl group (-NH2) on the silicon. The SiO2 surface has a large number of exposed silanol groups (Si-OH). The oxygen on the silanol groups undergoes nucleophilic substitution of the silicon on APTMS, removing one methanol CH3OH to form a Si-O-Si bond. This is the main way for silane coupling agents to form covalent bonds with the surface. Both APTMS and APTES silane coupling agents and their derivatives have a very important autocatalytic process. Because the amino group has good nucleophilic activity, it forms a Si-CCCN five-membered ring intermediate. Since the Si-N bond is extremely unstable and the amino group is a good leaving group, the nucleophilic substitution reaction on silicon can be catalyzed by the amino group of the molecule itself. Therefore, this site serves as a good adsorption site for the directional adsorption of h-BN, forming a thin barrier layer. The bottom of the trench has been passivated by HMDS and has no reaction sites, so it will not adsorb SAM molecules. The adhesion promoting layer 13 is used to reduce the thickness requirement of the traditional metal barrier layer and adheres the first diffusion barrier layer 14, achieving selective regional growth of the first diffusion barrier layer 14.
[0052] like Figure 6As shown, a first diffusion barrier layer 14 is formed. The adhesion promoting layer 13 adsorbs the precursor of the first diffusion barrier layer 14 through functional groups, so that the first diffusion barrier layer 14 is formed only on the sidewalls of the trench 12a and is used to block metal diffusion. Specifically, a chemical vapor deposition process is used to introduce BCl3 / NH3 at 350°C to form the first diffusion barrier layer 14. The first diffusion barrier layer 14 grows only in the region modified by the adhesion promoting layer 13. The material of the first diffusion barrier layer 14 is hexagonal boron nitride (h-BN). The adhesion promoting layer 13 selectively adsorbs the precursor of the first diffusion barrier layer 14 through functional groups, so that h-BN grows only on the sidewalls of the trench, avoiding bottom deposition from affecting metal filling. The first diffusion barrier layer 14 completely blocks metal diffusion by utilizing its grain boundary-free characteristics. The thickness d1 of the first diffusion barrier layer 14 is, for example, 0.5 nm to 1 nm. Compared with the prior art, the thickness of the first diffusion barrier layer 14 is reduced, while the wettability of the metal is improved.
[0053] like Figure 7 As shown, a second diffusion barrier layer 15 is formed, which covers the first diffusion barrier layer 14 and serves to support the first diffusion barrier layer 14 and prevent its breakage. The second diffusion barrier layer 15 is a high-entropy nitride (HEN) or high-entropy alloy (HEAs). High entropy refers to a solid solution formed by five or more metallic elements in near-equal atomic ratios with nitrogen, forming an amorphous or nanocrystalline structure to avoid grain boundaries, and forming refractory nitrides (HEN) to reduce interstitial space, thereby increasing the diffusion barrier of metallic copper. The entropy of the second diffusion barrier layer is greater than 1.95R, where R is a gas constant of approximately 8.314 J / (mol·K). The composition of the high-entropy nitride is (MoNbTaWV)N, where V can be replaced with Cr or Mn, and the second diffusion barrier layer 15 can be formed using a magnetron sputtering process. Specifically, firstly, a thin film is deposited on a prepared silicon substrate using a MoNbTaWV target. The sample is then placed in a vacuum furnace and subjected to rapid thermal annealing (RTA) at a temperature of 300-400°C, with a cooling rate of 50-100°C / s. After annealing, the sample is cooled in the furnace to obtain a self-formed high-entropy alloy nitride diffusion barrier layer. The sum of the thicknesses d of the first diffusion barrier layer 14 and the second diffusion barrier layer 15 is less than 4 nanometers.
[0054] like Figure 1As shown, a metal layer 16 is formed, which fills the trench 12a. The material of the metal layer 16 is, for example, copper. An adhesion promoting layer 13, a first diffusion barrier layer 14, and a second diffusion barrier layer 15 are formed between the metal layer 16 and the second dielectric layer 12. The first diffusion barrier layer 14 and the second diffusion barrier layer 15 are used to block metal diffusion.
[0055] In summary, in the metal interconnect structure provided by the embodiments of the present invention, the adhesion promoting layer in the metal interconnect structure is only located on the sidewall of the trench; the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is only formed on the sidewall of the trench and is used to block metal diffusion, avoiding the deposition of the first diffusion barrier layer at the bottom of the trench and affecting metal filling; the second diffusion barrier layer covers the first diffusion barrier layer, is used to block metal diffusion, and is used to support the first diffusion barrier layer and suppress the cracking of the first diffusion barrier layer; the metal layer fills the trench and covers the second diffusion barrier layer. The present invention uses an adhesion promoting layer to reduce the thickness requirement of traditional metal barrier layers, while improving the wettability of the metal. The material of the second diffusion barrier layer is a high-entropy nitride or a high-entropy alloy, which plays a major role in blocking metal diffusion. The total thickness of the first diffusion barrier layer and the second diffusion barrier layer is less than 4nm, which meets the process requirements below 40nm node; the lattice matching of the first diffusion barrier layer reduces the interface stress and avoids metal filling defects; and the vapor phase injection selective passivation process in which the adhesion promoting layer is only formed on the sidewall of the trench is compatible with existing production lines and does not require additional photolithography steps.
[0056] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.
Claims
1. A metal interconnect structure, characterized in that, include: A substrate on which a dielectric layer is formed, and trenches are formed within the dielectric layer; An adhesion promoting layer is located only on the sidewall of the trench; A first diffusion barrier layer, wherein the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion; A second diffusion barrier layer covers the first diffusion barrier layer and is used to support the first diffusion barrier layer and suppress its breakage, as well as to block metal diffusion. A metal layer that fills the trench and covers the second diffusion barrier layer.
2. The metal interconnect structure according to claim 1, characterized in that, The adhesion promoting layer is an aminosilane self-assembled monolayer, the first diffusion barrier layer is made of hexagonal boron nitride, the second diffusion barrier layer is made of high-entropy nitride or high-entropy alloy, and the entropy of the second diffusion barrier layer is greater than 1.95R, where R is a gas constant.
3. The metal interconnect structure according to claim 1, characterized in that, The combined thickness of the first diffusion barrier layer and the second diffusion barrier layer is less than 4 nanometers.
4. The metal interconnect structure according to claim 1, characterized in that, The dielectric layer includes a first dielectric layer and a second dielectric layer stacked in sequence. The trench penetrates the second dielectric layer and exposes the top surface of the first dielectric layer. The material of the first dielectric layer is SiCN, and the material of the second dielectric layer is SiOCH.
5. A method for forming a metal interconnect structure, characterized in that, include: A substrate is provided, on which a dielectric layer is formed, and trenches are formed within the dielectric layer; An adhesion-promoting layer is formed only on the sidewalls of the trench; A first diffusion barrier layer is formed, and the adhesion promoting layer adsorbs the precursor of the first diffusion barrier layer so that the first diffusion barrier layer is formed only on the sidewall of the trench and is used to block metal diffusion. A second diffusion barrier layer is formed, which covers the first diffusion barrier layer and serves to support the first diffusion barrier layer and suppress its breakage, as well as to block metal diffusion. A metal layer is formed, which fills the trench and covers the second diffusion barrier layer.
6. The method for forming a metal interconnect structure according to claim 5, characterized in that, The adhesion-promoting layer is formed by spin-coating organosilane molecules onto the dielectric layer and using a vapor-phase injection selective passivation process.
7. The method for forming a metal interconnect structure according to claim 5, characterized in that, A first diffusion barrier layer is formed using a chemical vapor deposition process, and the first diffusion barrier layer grows only in the region modified by the adhesion promotion layer.
8. The method for forming a metal interconnect structure according to claim 5, characterized in that, A second diffusion barrier layer is formed using a magnetron sputtering process.
9. The method for forming a metal interconnect structure according to claim 5, characterized in that, The adhesion promoting layer is an aminosilane self-assembled monolayer, the first diffusion barrier layer is made of hexagonal boron nitride, the second diffusion barrier layer is made of high-entropy nitride or high-entropy alloy, and the entropy of the second diffusion barrier layer is greater than 1.95R, where R is a gas constant.
10. The method for forming a metal interconnect structure according to claim 5, characterized in that, The combined thickness of the first diffusion barrier layer and the second diffusion barrier layer is less than 4 nanometers.