Semiconductor Structure and Method of Fabricating the Same

Abstract

An embodiment of the present invention provides a semiconductor structure and a manufacturing method thereof. The semiconductor structure includes: a doped conductive layer doped with doped ions; a metal conductive layer located on the doped conductive layer; a nitrogen-containing dielectric layer located on the metal conductive layer; a first nitrogen molybdenum compound layer located between the doped conductive layer and the metal conductive layer for electrically connecting the doped conductive layer and the metal conductive layer; a second nitrogen molybdenum compound layer located between the metal conductive layer and the nitrogen-containing dielectric layer, and the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is greater than that of nitrogen atoms in the first nitrogen molybdenum compound layer. The embodiment of the present invention is beneficial to improving the conductivity of the metal conductive layer.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductors, and in particular, to a semiconductor structure and a manufacturing method thereof. Background Art

[0002] With the improvement of performance requirements and technological progress, the size of semiconductor structures is continuously miniaturized, and the thickness of the film layers inside the semiconductor structures is continuously thinned. Due to the thinning of the film layer thickness, with the film layer material unchanged, the barrier performance of the film layer itself weakens. The performance of the originally specially provided barrier layer may no longer be able to meet the requirements, or the film layer that originally had specific electrical properties and could play a certain barrier role can no longer play a barrier effect. This makes the characteristics of some functional film layers easily affected by adjacent film layers, and further weakens the electrical properties of the functional film layers. Summary of the Invention

[0003] Embodiments of the present invention provide a semiconductor structure and a manufacturing method thereof, which are beneficial to improving the electrical characteristics of the metal conductive layer.

[0004] To solve the above problems, embodiments of the present invention provide a semiconductor structure, including: a doped conductive layer doped with doped ions; a metal conductive layer located on the doped conductive layer; a nitrogen-containing dielectric layer located on the metal conductive layer; a first nitrogen molybdenum compound layer located between the doped conductive layer and the metal conductive layer for electrically connecting the doped conductive layer and the metal conductive layer; a second nitrogen molybdenum compound layer located between the metal conductive layer and the nitrogen-containing dielectric layer, and the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is greater than the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer.

[0005] Correspondingly, embodiments of the present invention further provide a manufacturing method of a semiconductor structure, including: forming a doped conductive layer doped with doped ions; forming a first nitrogen molybdenum compound layer located on the doped conductive layer; forming a metal conductive layer located on the first nitrogen molybdenum compound layer, and the first nitrogen molybdenum compound layer is used to electrically connect the doped conductive layer and the metal conductive layer; forming a second nitrogen molybdenum compound layer located on the metal conductive layer, and the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is greater than the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer; forming a nitrogen-containing dielectric layer located on the second nitrogen molybdenum compound layer.

[0006] Compared with the prior art, the technical solutions provided by embodiments of the present invention have the following advantages:

[0007] In the above technical solution, controlling the relatively small atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer is beneficial to reducing the sheet resistance of the material of the first nitrogen molybdenum compound layer, so that the series resistance between the doped conductive layer and the metal conductive layer is small, ensuring that the first nitrogen molybdenum compound layer can not only prevent the mutual diffusion of metal atoms and doped ions, but also has little influence on the signal transmission performance between the metal conductive layer and the doped conductive layer; at the same time, controlling the relatively large atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is beneficial to making the second nitrogen molybdenum compound layer have strong blocking performance, and can better prevent the nitrogen atoms in the nitrogen-containing dielectric layer from diffusing into the metal conductive layer, ensuring that the metal conductive layer has good electrical conductivity characteristics.

[0008] In addition, controlling the relatively thick thickness of the first nitrogen molybdenum compound layer is beneficial to making the first nitrogen molybdenum compound layer have good blocking performance, and avoiding the mutual diffusion of metal ions in the metal conductive layer and doped ions in the doped conductive layer; at the same time, controlling the relatively thin thickness of the second nitrogen molybdenum compound layer is beneficial to reducing the overall thickness of the semiconductor structure while the blocking performance of the second nitrogen molybdenum compound layer meets the requirements, and realizing further miniaturization of the semiconductor structure size. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] One or more embodiments are illustrated by way of example in the accompanying drawings, which do not constitute a limitation to the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the drawings do not constitute a proportional limitation.

[0010] Figure 1 It is a schematic structural diagram of a semiconductor structure provided by an embodiment of the present invention;

[0011] Figures 2 to 4 It is a schematic structural diagram corresponding to each step of the manufacturing method of the semiconductor structure provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] In the manufacturing of semiconductor structures, due to the characteristics of small resistivity and stable physical and chemical properties of transition metal tungsten, tungsten can be used as the material of the metal conductive layer. However, tungsten is prone to lateral etching during the etching process, forming depressions, which leads to the narrowing of the lateral effective width of the metal conductive layer and the increase of the resistance of the metal conductive layer; due to the small dielectric constant and high hardness of silicon nitride, it can play both an electrical isolation and a supporting role at the same time. Therefore, silicon nitride is often used as the material of the protective layer of the metal conductive layer. However, during the process of generating silicon nitride material by high-temperature process, nitrogen atoms may react with tungsten to generate tungsten nitride material, and this reaction will reduce the film thickness of the metal conductive layer, thereby increasing the resistance of the metal conductive layer.

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will elaborate on each embodiment of the present invention with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present invention, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0014] Referring to Figure 1 , the semiconductor structure includes: a doped conductive layer 21 doped with doped ions; a metal conductive layer 23 located on the doped conductive layer 21; a nitrogen-containing dielectric layer 25 located on the metal conductive layer 23; a first nitrogen molybdenum compound layer 22 located between the doped conductive layer 21 and the metal conductive layer 23 for electrically connecting the doped conductive layer 21 and the metal conductive layer 23; and a second nitrogen molybdenum compound layer 24 located between the metal conductive layer 23 and the nitrogen-containing dielectric layer 25, where the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is greater than that in the first nitrogen molybdenum compound layer 22.

[0015] The doped ions in the doped conductive layer 21 can be P-type ions or N-type ions, and the bulk material of the doped conductive layer 21 can be adjusted according to actual needs, such as according to the contact resistance between the doped conductive layer 21 and adjacent film layers, the manufacturing cost of the doped conductive layer 21, and the electrical conductivity of the doped conductive layer 21. The bulk material refers to the material in the doped conductive layer 21 other than the doped ions, and the bulk material includes intrinsic semiconductor materials, such as amorphous silicon, polycrystalline silicon, or microcrystalline silicon. In this article, the doped conductive layer 21 made of polycrystalline silicon doped with N-type ions is taken as an example for detailed description.

[0016] The metal conductive layer 23 can be composed of one or more metal materials, or can be composed of metal materials and non-metal materials. If it is composed of metal materials and non-metal materials, the metal materials play the main role in conduction; one or more film layers including the first nitrogen molybdenum compound layer 22 can be provided between the metal conductive layer 23 and the doped conductive layer 21 to adjust the series resistance between the metal conductive layer 23 and the doped conductive layer 21, and the series resistance includes the contact resistance between adjacent film layers.

[0017] The material of the nitrogen-containing dielectric layer 25 can be adjusted according to actual performance requirements. For example, a material with a smaller dielectric constant can be selected to achieve good electrical isolation, a material with a lower hardness can be selected to achieve stress buffering, or a material with a higher hardness can be selected to achieve good support effects. In the actual process of preparation, silicon nitride or silicon oxynitride materials with relatively low cost and good support effects are generally selected to form the nitrogen-containing dielectric layer 25. Similarly, one or more film layers including the second nitrogen molybdenum compound layer 24 can be provided between the metal conductive layer 23 and the nitrogen-containing dielectric layer 25, and the multiple film layers are stacked in sequence in the direction of the doped conductive layer 21 facing the nitrogen-containing dielectric layer 25.

[0018] It should be emphasized that the application scenarios of the semiconductor structure provided by the embodiments of the present invention are not limited herein, and the materials and their component ratios of each film layer can be adjusted according to actual application scenarios. In one embodiment, the semiconductor structure provided by the embodiments of the present invention serves as a bit line structure, the doped conductive layer 21 serves as a bit line contact and is electrically connected to the active region 20, the metal conductive layer 23 transmits electrical signals as a bit line, and the nitrogen-containing dielectric layer 25 serves as a top insulating layer and mainly plays the roles of electrical isolation and supporting the upper film layer.

[0019] In this embodiment, in the direction of the doped conductive layer 21 facing the nitrogen-containing dielectric layer 25, the thickness of the first nitrogen molybdenum compound layer 22 is greater than that of the second nitrogen molybdenum compound layer 24. Compared with changing the material components of the first nitrogen molybdenum compound layer 22 to improve the barrier performance of the first nitrogen molybdenum compound layer 22, increasing the thickness of the first nitrogen molybdenum compound layer 22 in this way has a relatively small impact on the resistance of the first nitrogen molybdenum compound layer 22, which is beneficial to ensuring that the first nitrogen molybdenum compound layer 22 has both a barrier performance comparable to that of the second nitrogen molybdenum compound layer 24 and relatively excellent conductive performance.

[0020] It can be understood that since the atomic nucleus of a nitrogen atom is relatively small, the repulsive force between adjacent nitrogen atoms is relatively weak, and the distance between adjacent nitrogen atoms is relatively close. Based on this fact, the larger the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22, the smaller the distance between adjacent atoms in the first nitrogen molybdenum compound layer 22, and the more difficult it is for carriers to pass through the first nitrogen molybdenum compound layer 22 and the contact interface between the first nitrogen molybdenum compound layer 22 and the adjacent film layer. That is to say, as the atomic number ratio of nitrogen atoms increases, the barrier performance of the nitrogen molybdenum compound layer increases, and the resistance of the nitrogen molybdenum compound layer itself and the contact resistance with the adjacent film layer increase. Compared with increasing the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22, increasing the film thickness of the first nitrogen molybdenum compound layer 22 only changes the resistance of the first nitrogen molybdenum compound layer 22 itself, but does not change the contact resistance between the first nitrogen molybdenum compound layer 22 and the adjacent film layer. In this way, it is beneficial to adjust the barrier performance and conductive performance of the first nitrogen molybdenum compound layer 22 with relatively high precision, so that the first nitrogen molybdenum compound layer 22 has relatively balanced comprehensive performance.

[0021] In addition, since the nitrogen-containing dielectric layer 25 is a dielectric layer and there is no signal transmission between the nitrogen-containing dielectric layer 25 and the metal conductive layer 23, therefore, when setting the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24, the factor of resistance size does not need to be considered, and only the diffusion of nitrogen atoms in the nitrogen-containing dielectric layer 25 needs to be inhibited. In other words, the blocking of nitrogen atoms can be achieved by increasing the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24. When the blocking performance of the second nitrogen molybdenum compound layer 24 meets the requirements, the thickness of the second nitrogen molybdenum compound layer 24 can be reduced to achieve the thinning of the overall semiconductor structure.

[0022] In this embodiment, the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22 is 10% to 20%, for example, 13%, 15% or 17%. In the direction of the doped conductive layer 21 facing the nitrogen-containing dielectric layer 25, the thickness of the first nitrogen molybdenum compound layer 22 is 2 nm to 4 nm, for example, 2.5 nm, 3 nm or 3.5 nm. If the atomic number ratio of nitrogen atoms or the thickness of the first nitrogen molybdenum compound layer 22 is too large, it is easy to cause a large resistance of the first nitrogen molybdenum compound layer 22, and then weaken the signal transmission performance of the first nitrogen molybdenum compound layer 22; if the atomic number ratio of nitrogen atoms or the thickness of the first nitrogen molybdenum compound layer 22 is too small, it is easy to cause a weak blocking performance of the first nitrogen molybdenum compound layer 22, which is not conducive to inhibiting the mutual diffusion of metal ions in the metal conductive layer 23 and doped ions in the doped conductive layer 21. The mutual diffusion of metal ions and doped ions will cause the deterioration of the conductive performance of the metal conductive layer 23 and the doped conductive layer 21, and then affect the signal transmission performance of the metal conductive layer 23 and the doped conductive layer 21.

[0023] In this embodiment, the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is 30% to 40%, for example, 33%, 35% or 37%. If the atomic number ratio of nitrogen atoms is too small, it is not conducive to blocking the diffusion of nitrogen atoms in the nitrogen-containing dielectric layer 25 to the metal conductive layer 23; if the atomic number ratio of nitrogen atoms is too large, it is easy to become a pollution source of nitrogen atoms itself, that is, the nitrogen atoms in the second nitrogen molybdenum compound layer 24 diffuse into the metal conductive layer 23.

[0024] It can be understood that setting a relatively large proportion of the number of nitrogen atoms in the second nitrogen molybdenum compound layer 24 enables the second nitrogen molybdenum compound layer 24 to block the nitrogen atoms in the nitrogen-containing dielectric layer 25 through two mechanisms, as follows: First, with a relatively large proportion of the number of nitrogen atoms, the spacing between adjacent atoms is small, and nitrogen atoms are not easily passed through. Second, with a relatively large proportion of the number of nitrogen atoms, the doping concentration of nitrogen atoms is relatively high (nitride can be understood as nitrogen atoms doped in another kind of atom). The doping concentration of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is greater than or equal to the doping concentration of nitrogen atoms in the nitrogen-containing dielectric layer 25, or the difference between the doping concentration of nitrogen atoms in the second nitrogen molybdenum compound layer 24 and the doping concentration of nitrogen atoms in the nitrogen-containing dielectric layer 25 is small. In this way, it is beneficial to prevent the nitrogen atoms in the nitrogen-containing dielectric layer 25 from diffusing into the metal conductive layer 23 based on the concentration difference.

[0025] In this embodiment, as the proportion of the number of nitrogen atoms in the second nitrogen molybdenum compound layer 24 changes, the thickness of the second nitrogen molybdenum compound layer 24 changes accordingly to ensure that the blocking performance of the second nitrogen molybdenum compound layer 24 is higher than a preset level. Exemplarily, in the direction of the doped conductive layer 21 facing the nitrogen-containing dielectric layer 25, the thickness of the second nitrogen molybdenum compound layer 24 is 0.5 nm to 1.5 nm, such as 0.8 nm, 1 nm, or 1.2 nm. If the thickness of the second nitrogen molybdenum compound layer 24 is too thick, it is not conducive to reducing the overall size of the semiconductor structure, and at the same time, it may cause itself to become a nitrogen atom source, that is, the nitrogen atoms contained in itself diffuse into the metal conductive layer 23. If the thickness of the second nitrogen molybdenum compound layer 24 is too thin, it is not conducive to blocking the diffusion of nitrogen atoms in the nitrogen-containing dielectric layer 25 into the metal conductive layer 23.

[0026] In this embodiment, the material of the metal conductive layer 23 includes molybdenum metal. Compared with tungsten metal, molybdenum metal is not easily laterally etched during the etching process, which is beneficial to ensuring that each discrete metal conductive layer 23 formed through patterned etching has a preset lateral effective width d, so that the metal conductive layer 23 has a smaller resistance.

[0027] In this embodiment, the metal conductive layer 23 is composed of a single metal material, molybdenum. In this way, the first nitrogen molybdenum compound layer 22, the metal conductive layer 23, and the second nitrogen molybdenum compound layer 24 can be continuously formed in the same reaction chamber without interrupting the process to adjust the metal source, which is beneficial to avoiding the destruction of the vacuum environment and the oxidation of the film surface, and is beneficial to ensuring the continuity between different film layers. It can be understood that if the metal conductive layer 23 also includes other metal materials, a cleaning process or chamber replacement is required after forming the metal conductive layer 23 to avoid the contamination of the formation of the second nitrogen molybdenum compound layer 24 by other metal materials remaining in the reaction chamber.

[0028] In this embodiment, both the first molybdenum nitride layer 22 and the second molybdenum nitride layer 24 contain a molybdenum nitride material with a polycrystalline structure. Exemplarily, the molybdenum nitride material with a polycrystalline structure includes polycrystalline γ-Mo2N. Further, the crystallinity of the molybdenum nitride material in the first molybdenum nitride layer 22 is greater than that of the molybdenum nitride material in the second molybdenum nitride layer 24. It should be noted that the larger the atomic number ratio of nitrogen atoms, the more difficult it is for the amorphous molybdenum nitride material to crystallize. Before crystallization, if both the first molybdenum nitride layer 22 and the second molybdenum nitride layer 24 are amorphous molybdenum nitride materials, then under the same crystallization conditions, the crystallinity of the molybdenum nitride material in the first molybdenum nitride layer 22 is greater than that of the molybdenum nitride material in the second molybdenum nitride layer 24. The higher the crystallinity, the larger the grain size, the fewer the grain boundaries, the more regular the grain arrangement, and the lower the sheet resistance of the molybdenum nitride material. The larger crystallinity of the molybdenum nitride material in the first molybdenum nitride layer 22 is beneficial to ensuring that the first molybdenum nitride layer 22 has high signal transmission performance.

[0029] In this embodiment, the atomic number ratio of nitrogen atoms in the first molybdenum nitride layer is controlled to be relatively small, reducing the sheet resistance of the material of the first molybdenum nitride layer, which is beneficial to making the series resistance between the doped conductive layer and the metal conductive layer smaller, ensuring that the first molybdenum nitride layer can both block the mutual migration and penetration of metal atoms and doped ions, and has a relatively small impact on the electrical connection performance of the metal conductive layer and the doped conductive layer. At the same time, the atomic number ratio of nitrogen atoms in the second molybdenum nitride layer is controlled to be relatively large, which is beneficial to making the second molybdenum nitride layer have strong blocking performance and being able to better block the migration of nitrogen atoms in the nitrogen-containing dielectric layer to the metal conductive layer, ensuring that the metal conductive layer has good conductive characteristics.

[0030] Correspondingly, an embodiment of the present invention further provides a manufacturing method of a semiconductor structure, which can be used to prepare the above semiconductor structure.

[0031] Figures 1 to 4 It is a schematic structural diagram corresponding to each step of the manufacturing method of the semiconductor structure provided by the embodiment of the present invention. The manufacturing method of the semiconductor structure includes the following steps:

[0032] Refer to Figure 2 , a doped conductive layer 21 and a first molybdenum nitride layer 22 are formed. The doped conductive layer 21 is doped with doped ions, and the first molybdenum nitride layer 22 is located on the doped conductive layer 21.

[0033] In this embodiment, the doped conductive layer 21 is connected to the active region 20 at the bottom, and the isolation structure 20a surrounds the active region 20 for isolating adjacent active regions 20. The process steps for forming the first nitrogen molybdenum compound layer 22 include: introducing a nitrogen source gas and molybdenum metal; performing an ionization process to form nitrogen plasma so that the nitrogen plasma reacts with the molybdenum metal to generate a nitrogen molybdenum compound, and the nitrogen molybdenum compound is deposited to form a nitrogen molybdenum compound layer, and the nitrogen molybdenum compound layer has an amorphous structure. Among them, the molybdenum metal can be fed in with an inert gas, the nitrogen source gas includes nitrogen, and the inert gas includes argon.

[0034] Reference Figure 3 , a metal conductive layer 23 and a second nitrogen molybdenum compound layer 24 are formed. The metal conductive layer 23 is located on the first nitrogen molybdenum compound layer 22. The first nitrogen molybdenum compound layer 22 is used for electrically connecting the doped conductive layer 21 and the metal conductive layer 23. The second nitrogen molybdenum compound layer 24 is located on the metal conductive layer 23, and the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is greater than the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22.

[0035] In this embodiment, the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is greater than the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22, and the barrier performance of the material of the second nitrogen molybdenum compound layer 24 is greater than the barrier performance of the material of the first nitrogen molybdenum compound layer 22. If the first nitrogen molybdenum compound layer 22 is to have a strong blocking effect, then in the direction of the doped conductive layer 21 facing the second nitrogen molybdenum compound layer 24, the thickness of the first nitrogen molybdenum compound layer 22 is set to be greater than the thickness of the second nitrogen molybdenum compound layer 24.

[0036] In this embodiment, the process steps for forming the first nitrogen molybdenum compound layer 22 and the second nitrogen molybdenum compound layer 24 are the same, and the only difference is that the flow rate of the nitrogen source gas for forming the first nitrogen molybdenum compound layer 22 is less than the flow rate of the nitrogen source gas for forming the second nitrogen molybdenum compound layer 24, so that the atomic number ratio of nitrogen atoms in the second nitrogen molybdenum compound layer 24 is greater than the atomic number ratio of nitrogen atoms in the first nitrogen molybdenum compound layer 22.

[0037] Furthermore, during the process of forming the first nitrogen molybdenum compound layer 22 and the second nitrogen molybdenum compound layer 24, the ratio of the flow rate of the nitrogen source gas to the sum of the flow rates of the nitrogen source gas and the inert gas is the same, and the process temperature is the same. In this way, it is beneficial to make the properties of the first nitrogen molybdenum compound layer 22 and the second nitrogen molybdenum compound layer 24 similar except for the atomic number ratio. Exemplarily, during the process of forming the first nitrogen molybdenum compound layer 22, the flow rate of the nitrogen source gas is 35 sccm, the flow rate of the inert gas is 15 sccm, the above flow rate ratio is 70%, and the process temperature is 250°C. During the process of forming the second nitrogen molybdenum compound layer 24, the flow rate of the nitrogen source gas is 70 sccm, the flow rate of the inert gas is 35 sccm, the flow rate ratio is maintained at 70%, and the process temperature is maintained at 250°C.

[0038] In this embodiment, the ionization process for forming the first nitrogen molybdenum compound layer 22 is denoted as the first ionization process, and the ionization process for forming the second nitrogen molybdenum compound layer 24 is denoted as the second ionization process. Since the thickness of the first nitrogen molybdenum compound layer 22 is greater than that of the second nitrogen molybdenum compound layer 24 under the condition of similar barrier performance, the specific parameters of the first ionization process are different from those of the second ionization process. Specifically, since the greater the DC power supply power, the faster the reaction rate between the nitrogen plasma and the molybdenum metal, and the faster the deposition rate of the nitrogen molybdenum compound layer, the DC power supply power of the first ionization process can be set to be greater than or equal to that of the second ionization process, so that the first nitrogen molybdenum compound layer 22 has a shorter production duration; correspondingly, since the greater the RF bias power, the better the film layer uniformity, and a thicker film layer has a lower requirement for film layer uniformity, the RF bias power of the first ionization process can be set to be less than or equal to that of the second ionization process, so that the second nitrogen molybdenum compound layer 24 has a higher film layer uniformity, that is, the second nitrogen molybdenum compound layer 24 has good barrier performance.

[0039] Among them, the DC power supply power of the first ionization process can be set to be 2000W - 3000W, such as 2300W, 2500W or 2700W, and the DC power supply power of the second ionization process is 1500W - 2500W, such as 1700W, 2000W or 2300W. A too large DC power supply power may cause the deposition rate of the nitrogen molybdenum compound layer to be too fast, making it difficult to accurately control the thicknesses of the first nitrogen molybdenum compound layer 22 and the second nitrogen molybdenum compound layer 24. A too small DC power supply power may cause the deposition rate of the nitrogen molybdenum compound layer to be too slow, which is not conducive to shortening the overall production duration; correspondingly, the RF bias power of the first ionization process can be set to be 500W - 750W, such as 550W, 600W, 650W and 700W, and the RF bias power of the second ionization process is set to be 600W - 800W, such as 650W, 700W or 750W. A too large RF bias power is not conducive to reducing the process energy consumption and process cost, and a too small RF bias power is not conducive to improving the uniformity and density of the nitrogen molybdenum compound layer.

[0040] Refer to Figure 4 and Figure 1 , a nitrogen-containing dielectric layer 25 is formed, and the nitrogen-containing dielectric layer 25 is located on the second nitrogen molybdenum compound layer 24; a patterning etching process is performed to form a plurality of discrete semiconductor structures, and the semiconductor structures can be bit line structures.

[0041] In this embodiment, a nitrogen-containing dielectric layer 25 is grown in a heat treatment process environment. Affected by the high-temperature process, at least part of the amorphous structure in the nitrogen molybdenum compound layer (i.e., the first nitrogen molybdenum compound layer 22 and the second nitrogen molybdenum compound layer 24) will be transformed into a polycrystalline structure. At the same time, due to the relatively large proportion of nitrogen atoms in the second nitrogen molybdenum compound layer 24, the crystallinity of the nitrogen molybdenum compound material in the second nitrogen molybdenum compound layer 24 is relatively low. In other embodiments, after the second nitrogen molybdenum compound layer is formed, a heat treatment process is carried out to transform at least part of the amorphous structure in the nitrogen molybdenum compound layer into a polycrystalline structure, or after the nitrogen-containing dielectric layer 25 is formed, at least part of the amorphous structure is transformed into a polycrystalline structure by using other heat treatment processes.

[0042] In this embodiment, the metal conductive layer 23 is a molybdenum metal layer, and the first nitrogen molybdenum compound layer 22, the second nitrogen molybdenum compound layer 24, and the molybdenum metal layer are formed in the same reaction chamber.

[0043] In the above technical solution, the proportion of nitrogen atoms in the first nitrogen molybdenum compound layer is controlled to be relatively small, the sheet resistance of the material of the first nitrogen molybdenum compound layer is reduced, which is beneficial to having a relatively small series resistance between the doped conductive layer and the metal conductive layer, ensuring that the first nitrogen molybdenum compound layer can not only block the mutual migration and penetration of metal atoms and doped ions, but also have a relatively small impact on the electrical connection performance of the metal conductive layer and the doped conductive layer. At the same time, the proportion of nitrogen atoms in the second nitrogen molybdenum compound layer is controlled to be relatively large, which is beneficial to making the second nitrogen molybdenum compound layer have a strong blocking performance and being able to better block the migration of nitrogen atoms in the nitrogen-containing dielectric layer to the metal conductive layer, ensuring that the metal conductive layer has good electrical conductivity characteristics.

[0044] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present invention. In practical applications, various changes can be made in form and details without departing from the spirit and scope of the present invention. Any person skilled in the art can make their respective changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A semiconductor structure, characterized in that it includes: a doped conductive layer doped with doped ions; a metal conductive layer located on the doped conductive layer; a nitrogen-containing dielectric layer located on the metal conductive layer; a first nitrogen molybdenum compound layer located between the doped conductive layer and the metal conductive layer for electrically connecting the doped conductive layer and the metal conductive layer; a second nitrogen molybdenum compound layer located between the metal conductive layer and the nitrogen-containing dielectric layer, and the atomic ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is greater than the atomic ratio of nitrogen atoms in the first nitrogen molybdenum compound layer.

2. The semiconductor structure according to claim 1, characterized in that in the direction of the doped conductive layer towards the nitrogen-containing dielectric layer, the thickness of the first nitrogen molybdenum compound layer is greater than the thickness of the second nitrogen molybdenum compound layer.

3. The semiconductor structure according to claim 1, characterized in that the atomic ratio of nitrogen atoms in the first nitrogen molybdenum compound layer is 10% - 20%, and in the direction of the doped conductive layer towards the nitrogen-containing dielectric layer, the thickness of the first nitrogen molybdenum compound layer is 2nm - 4nm.

4. The semiconductor structure according to claim 1, characterized in that the atomic ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is 30% - 40%.

5. The semiconductor structure according to claim 4, characterized in that in the direction of the doped conductive layer towards the nitrogen-containing dielectric layer, the thickness of the second nitrogen molybdenum compound layer is 0.5nm - 1.5nm.

6. The semiconductor structure according to claim 1, characterized in that the material of the metal conductive layer contains molybdenum metal.

7. The semiconductor structure according to claim 1, characterized in that both the first nitrogen molybdenum compound layer and the second nitrogen molybdenum compound layer contain a nitrogen molybdenum compound material with a polycrystalline structure.

8. The semiconductor structure according to claim 7, characterized in that the crystallinity of the nitrogen molybdenum compound material in the first nitrogen molybdenum compound layer is greater than the crystallinity of the nitrogen molybdenum compound material in the second nitrogen molybdenum compound layer.

9. The semiconductor structure according to claim 7, characterized in that the nitrogen molybdenum compound material with a polycrystalline structure includes polycrystalline γ-Mo2N.

10. The semiconductor structure according to claim 1, characterized in that the doped conductive layer is electrically connected to the active region, the material of the doped conductive layer includes doped polysilicon, and the doped ions include N-type ions.

11. A method for manufacturing a semiconductor structure, characterized in that it includes: forming a doped conductive layer doped with doped ions; forming a first nitrogen molybdenum compound layer located on the doped conductive layer; forming a metal conductive layer located on the first nitrogen molybdenum compound layer, and the first nitrogen molybdenum compound layer is used for electrically connecting the doped conductive layer and the metal conductive layer; forming a second nitrogen molybdenum compound layer located on the metal conductive layer, and the atomic ratio of nitrogen atoms in the second nitrogen molybdenum compound layer is greater than the atomic ratio of nitrogen atoms in the first nitrogen molybdenum compound layer; A nitrogen-containing dielectric layer is formed, and the nitrogen-containing dielectric layer is located on the second nitrogen molybdenum compound layer.

12. The method for manufacturing a semiconductor structure according to claim 11, wherein the process steps of forming the first nitrogen molybdenum compound layer and the second nitrogen molybdenum compound layer both include: introducing a nitrogen source gas and molybdenum metal; wherein, the flow rate of the nitrogen source gas for forming the first nitrogen molybdenum compound layer is less than the flow rate of the nitrogen source gas for forming the second nitrogen molybdenum compound layer; performing an ionization process to form nitrogen plasma, so that the nitrogen plasma reacts with the molybdenum metal to generate a nitrogen molybdenum compound, and the nitrogen molybdenum compound is deposited to form a nitrogen molybdenum compound layer, and the nitrogen molybdenum compound layer has an amorphous structure.

13. The method for manufacturing a semiconductor structure according to claim 12, wherein the ionization process for forming the first nitrogen molybdenum compound layer is a first ionization process, the ionization process for forming the second nitrogen molybdenum compound layer is a second ionization process, the DC power of the first ionization process is greater than or equal to the DC power of the second ionization process, and the RF bias power of the first ionization process is less than or equal to the RF bias power of the second ionization process.

14. The method for manufacturing a semiconductor structure according to claim 13, wherein the DC power of the first ionization process is 2000W to 3000W, the RF bias power is 500W to 750W, the DC power of the second ionization process is 1500W to 2500W, and the RF bias power is 600W to 800W.

15. The method for manufacturing a semiconductor structure according to claim 11, wherein further comprising: performing a heat treatment process to convert at least part of the amorphous structure in the nitrogen molybdenum compound layer into a polycrystalline structure.

16. The method for manufacturing a semiconductor structure according to claim 11, wherein the metal conductive layer is a molybdenum metal layer, and the first nitrogen molybdenum compound layer, the second nitrogen molybdenum compound layer, and the molybdenum metal layer are formed in the same reaction chamber.

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