Patent Description:
Embodiments of this disclosure relate to but are not limited to a semiconductor structure and a method for manufacturing same.

With the improvement of performance requirements and technological progress, semiconductor structures have been gradually miniaturized, and the thicknesses of film layers inside the semiconductor structures have been constantly decreased. Due to the decrease in thickness of the film layer, the blocking performance of the film layer per se will be weakened under the condition that the material of the film layer remains unchanged, and thus the performance of an original specially-arranged blocking layer may no longer satisfy the requirements or the film layer that has a certain blocking effect and originally has specific electrical characteristics can no longer yield the blocking effect, which makes the characteristics of some functional film layers susceptible to neighboring film layers and then weakens the electrical characteristics of the functional film layers. Background may be found in <CIT>.

Embodiments of this disclosure provide a semiconductor structure and a method for manufacturing same, which are conducive to improving electrical characteristics of a metal conductive layer.

A semiconductor structure according to the invention comprises a doped conductive layer, doped with dopant ions; a metal conductive layer, located above the doped conductive layer; a nitrogen-containing dielectric layer, located above the metal conductive layer; a first molybdenum nitride layer, located between the doped conductive layer and the metal conductive layer and configured to be electrically connected to the doped conductive layer and the metal conductive layer; and a second molybdenum nitride layer, located between the metal conductive layer and the nitrogen-containing dielectric layer, where an atomic ratio of nitrogen atoms in the second molybdenum nitride layer is greater than an atomic ratio of nitrogen atoms in the first molybdenum nitride layer.

In one embodiment, a thickness of the first molybdenum nitride layer is greater than a thickness of the second molybdenum nitride layer in a direction from the doped conductive layer to the nitrogen-containing dielectric layer.

In one embodiment, an atomic ratio of nitrogen atoms in the first molybdenum nitride layer is <NUM>% to <NUM>%, and the thickness of the first molybdenum nitride layer is <NUM> to <NUM> in the direction from the doped conductive layer to the nitrogen-containing dielectric layer.

In one embodiment, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer is <NUM>% to <NUM>%.

In one embodiment, the thickness of the second molybdenum nitride layer is <NUM> to <NUM> in the direction from the doped conductive layer to the nitrogen-containing dielectric layer.

In one embodiment, a material of the metal conductive layer includes metal molybdenum.

In one embodiment, the first molybdenum nitride layer and the second molybdenum nitride layer each include a molybdenum nitride material having a polycrystalline structure.

In one embodiment, crystallinity of the molybdenum nitride material in the first molybdenum nitride layer is greater than crystallinity of the molybdenum nitride material in the second molybdenum nitride layer.

In one embodiment, the molybdenum nitride material having a polycrystalline structure includes polycrystalline γ-Mo<NUM>N.

In one embodiment, the doped conductive layer is electrically connected to an active area, the material of the doped conductive layer includes doped polysilicon, and the dopant ions include N-type ions.

A method for manufacturing a semiconductor structure, according to the invention includes the following operations. A doped conductive layer is formed, in which the doped conductive layer is doped with dopant ions. A first molybdenum nitride layer is formed, which is on the doped conductive layer. A metal conductive layer is formed, which is on the first molybdenum nitride layer, and is configured to be electrically connected to the doped conductive layer and the metal conductive layer. A second molybdenum nitride layer is formed, which is on the metal conductive layer, and an atomic ratio of nitrogen atoms in the second molybdenum nitride layer is greater than an atomic ratio of nitrogen atoms in the first molybdenum nitride layer. A nitrogen-containing dielectric layer is formed, which on the second molybdenum nitride layer.

In one embodiment, forming the first molybdenum nitride layer and forming the second molybdenum nitride layer include the following operations.

A nitrogen source gas and metal molybdenum are introduced, in which a flow rate of the nitrogen source gas for forming the first molybdenum nitride layer is smaller than a flow rate of the nitrogen source gas for forming the second molybdenum nitride layer.

An ionization process is performed to form nitrogen plasma, so that the nitrogen plasma reacts with the metal molybdenum to produce molybdenum nitride, and the molybdenum nitride is deposited to form a molybdenum nitride layer, which has an amorphous structure.

In one embodiment, the ionization process of forming the first molybdenum nitride layer is a first ionization process, the ionization process of forming the second molybdenum nitride layer is a second ionization process, a direct-current power supply power of the first ionization process is higher than or equal to a direct-current power supply power of the second ionization process, and a radio frequency bias power of the first ionization process is lower than or equal to a radio frequency bias power of the second ionization process.

In one embodiment, the direct-current power supply power of the first ionization process is <NUM> W to <NUM> W and the radio frequency bias power thereof is <NUM> W to <NUM> W, and the direct-current power supply power of the second ionization process is <NUM> W to <NUM> W and the radio frequency bias power thereof is <NUM> W to <NUM> W.

In one embodiment, the method for manufacturing a semiconductor structure further includes the following operation. A thermal treatment process is performed, so that at least part of an amorphous structure in the molybdenum nitride layer is converted into a polycrystalline structure.

In one embodiment, the metal conductive later is a metal molybdenum layer, and the first molybdenum nitride layer, the second molybdenum nitride layer and the metal molybdenum layer are formed in a same reaction chamber.

Compared with the related art, the technical solutions provided in the embodiments of this disclosure have the following advantages.

In the foregoing technical solutions, the atomic ratio of nitrogen atoms in the first molybdenum nitride layer is controlled to be smaller, which is conducive to decreasing the sheet resistance of the material of the first molybdenum nitride layer, so that there is a small series resistance between the doped conductive layer and the metal conductive layer, and the first molybdenum nitride layer not only can block mutual diffusion between metal atoms and the dopant ions, but also has little influence on signal transmission performance between the metal conductive layer and the doped conductive layer. Meanwhile, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer is controlled to be larger, which is conducive to enabling strong blocking performance of the second molybdenum nitride layer, better blocking diffusion of nitrogen atoms in the nitrogen-containing dielectric layer to the metal conductive layer, so that it is ensured that the metal conductive layer has better conductive characteristics.

In addition, the thickness of the first molybdenum nitride layer is controlled to be larger, which is conducive to enabling better blocking performance of the first molybdenum nitride layer and avoiding mutual diffusion between metal ions in the metal conductive layer and the dopant ions in the doped conductive layer. Meanwhile, the thickness of the second molybdenum nitride layer is controlled to be smaller, which is conducive to decreasing the overall thickness of the semiconductor structure to further miniaturize the semiconductor structure while the blocking performance of the second molybdenum nitride layer is satisfied.

One or more embodiments are exemplified by figures in the corresponding accompany drawings. These exemplary illustrations do not constitute any limitation to the embodiments. The elements with the same reference numerals in the accompany drawings are denoted as similar elements. Unless otherwise stated, the figures in the accompany drawings do not constitute any scale limitation.

In manufacturing of a semiconductor structure, since transition metal tungsten is featured by a small specific electrical resistance, stable physical and chemical performance, etc., tungsten can serve as the material of a metal conductive layer. However, tungsten is prone to be lateral etched during an etching process to cause a recess, which may lead to a decreased lateral effective width of the metal conductive layer and an increased resistance of the metal conductive layer. Since silicon nitride has a small dielectric constant and high hardness and thus simultaneously has electrical isolation and support effects, silicon nitride often serves as the material of a protective layer of the metal conductive layer. However, during producing the silicon nitride material using a high-temperature process, nitrogen atoms may react with tungsten to produce a tungsten nitride material, which may decrease the film thickness of the metal conductive layer and then increase the resistance of the metal conductive layer.

In order to make the objectives, technical solutions and advantages of embodiments of this disclosure clearer, various embodiments of this disclosure will be described in detail below in combination with the accompanying drawings. However, it can be understood by persons of ordinary skills in the art that, in various embodiments of this disclosure, many technical details have been proposed in order to give the reader a better understanding of this disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various changes and modifications based on the following various embodiments.

Referring to <FIG>, a semiconductor structure includes: a doped conductive layer <NUM>, doped with dopant ions; a metal conductive layer <NUM>, located above the doped conductive layer <NUM>; a nitrogen-containing dielectric layer <NUM>, located above the metal conductive layer <NUM>; a first molybdenum nitride layer <NUM>, located between the doped conductive layer <NUM> and the metal conductive layer <NUM> and configured to be electrically connected to the doped conductive layer <NUM> and the metal conductive layer <NUM>; and a second molybdenum nitride layer <NUM>, located between the metal conductive layer <NUM> and the nitrogen-containing dielectric layer <NUM>, in which an atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is greater than an atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>.

The dopant ions in the doped conductive layer <NUM> may be P-type ions or N-type ions; and a main material of the doped conductive layer <NUM> may be adjusted according to actual requirements, for example, depending on the contact resistance between the doped conductive layer <NUM> and a neighboring film layer, the cost of manufacturing the doped conductive layer <NUM>, and the conductive performance of the doped conductive layer <NUM>. The main material refers to the material other than the dopant ions in the doped conductive layer <NUM>, and the main material includes an intrinsic semiconductor material such as amorphous silicon, polysilicon or microcrystalline silicon. The text is explained in detail by taking the doped conductive layer <NUM> being a polysilicon material doped with N-type ions as an example.

The metal conductive layer <NUM> may be composed of one or more metal materials, and may also be composed of a metal material and a non-metal material. When the metal conductive layer <NUM> is composed of the metal material and the non-metal material, the metal material yields the main conductive effect. One or more film layers including the first molybdenum nitride layer <NUM> may be provided between the metal conductive layer <NUM> and the doped conductive layer <NUM>, so as to adjust a series resistance between the metal conductive layer <NUM> and the doped conductive layer <NUM>, in which the series resistance includes a contact resistance between neighboring film layers.

The material of the nitrogen-containing dielectric layer <NUM> may be adjusted according to actual performance requirements. For example, the material having a small dielectric constant is selected to achieve good electrical isolation, the material having low hardness is selected to achieve stress buffer, or the material having high hardness is selected to achieve a good support effect. During practical process preparation, a silicon nitride or silicon oxynitride material having a good support effect and a low lost is generally selected to form the nitrogen-containing dielectric layer <NUM>. Similarly, one or more film layers including the second molybdenum nitride layer <NUM> may be provided between the metal conductive layer <NUM> and the nitrogen-containing dielectric layer <NUM>, and the multiple film layers are stacked in sequence in a direct from the doped conductive layer <NUM> to the nitrogen-containing dielectric layer <NUM>.

It should be noted that an application scene of the semiconductor structure provided in the embodiments of this disclosure is not limited by those in the text, and the material of each film layer and the ratio of components thereof can be adjusted according to the actual application scene. In one embodiment, the semiconductor structure provided in the embodiments of this disclosure serves as a bit line structure, in which the doped conductive layer <NUM> serves as a bit line to contact and be electrically connected to an active area <NUM>, the metal conductive layer <NUM> serves as a bit line to transmit electrical signals, and the nitrogen-containing dielectric layer <NUM> serves as a top insulating layer and mainly yields the effects of electrical isolation and supporting an upper film layer.

In this embodiment, the thickness of the first molybdenum nitride layer <NUM> is greater than the thickness of the second molybdenum nitride layer <NUM> in a direction from the doped conductive layer <NUM> to the nitrogen-containing dielectric layer <NUM>. Compared with the approach of changing composition of the material of the first molybdenum nitride layer <NUM> to improve the blocking performance of the first molybdenum nitride layer <NUM>, the approach of increasing the thickness improves the blocking performance of the first molybdenum nitride layer <NUM> and has little influence on the resistance of the first molybdenum nitride layer <NUM>, which is conducive to ensuring that the first molybdenum nitride layer <NUM> not only has the equivalent blocking performance to that of the second first molybdenum nitride layer <NUM>, but also has excellent conductive performance.

It can be understood that since the atomic nucleus of the nitrogen atom is small, the repulsive force between neighboring nitrogen atoms is weak and the distance between neighboring nitrogen atoms is short. Based on this fact, the greater the atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>, the shorter the distance between neighboring atoms in the first molybdenum nitride layer <NUM>, and the less likely it is for a carrier to pass through the first molybdenum nitride layer <NUM> and to pass through a contact interface between the first molybdenum nitride layer <NUM> and a neighboring film layer. That is to say, as the atomic ratio of nitrogen atoms increases, the blocking performance of the molybdenum nitride layer is improved, and the resistance of the molybdenum nitride layer per se and the contact resistance with the neighboring film layer increase. Compared with increasing the atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>, increasing the film thickness of the first molybdenum nitride layer <NUM> will merely change the resistance of the first molybdenum nitride layer <NUM> per se, but will not change the contact resistance between the first molybdenum nitride layer <NUM> and the neighboring film layer, which is conducive to adjusting the blocking performance and the conductive performance of the first molybdenum nitride layer <NUM> more precisely, so that the first molybdenum nitride layer <NUM> has relatively balanced comprehensive performance.

In addition, since the nitrogen-containing dielectric layer <NUM> is a dielectric layer and there is no signal transmission between the nitrogen-containing dielectric layer <NUM> and the metal conductive layer <NUM>. When setting the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM>, it is unnecessary to consider the factor of resistance, and it is only required to suppress diffusion of the nitrogen atoms in the nitrogen-containing dielectric layer <NUM>. In other words, the nitrogen atoms can be blocked by increasing the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM>, and in the case that the blocking performance of the second molybdenum nitride layer <NUM> can satisfy the requirements, the thickness of the second molybdenum nitride layer <NUM> can be decreased, so as to thin the entire semiconductor structure.

In this embodiment, the atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM> is <NUM>% to <NUM>%, for example, <NUM>%, <NUM>% or <NUM>%, and the thickness of the first molybdenum nitride layer <NUM> is <NUM> to <NUM>, for example, <NUM>, <NUM> or <NUM>, in the direction from the doped conductive layer <NUM> to the nitrogen-containing dielectric layer <NUM>. When the atomic ratio of nitrogen atoms or the thickness of the first molybdenum nitride layer <NUM> is too large, it is likely to cause a large resistance of the first molybdenum nitride layer <NUM> and then cause weakened signal transmission performance of the first molybdenum nitride layer <NUM>. Whereas when the atomic ratio of nitrogen atoms or the thickness of the first molybdenum nitride layer <NUM> is too small, it is likely to cause weak blocking performance of the first molybdenum nitride layer <NUM>, which is not conducive to suppressing mutual diffusion between the metal ions of the metal conductive layer <NUM> and the dopant ions of the doped conductive layer <NUM>. The mutual diffusion between the metal ions and the dopant ions may cause degraded conductive performance of the metal conductive layer <NUM> and the doped conductive layer <NUM>, thereby influencing the signal transmission performance of the metal conductive layer <NUM> and the doped conductive layer <NUM>.

In this embodiment, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is <NUM>% to <NUM>%, for example, <NUM>%, <NUM>% or <NUM>%. When the atomic ratio of nitrogen atoms is small, it is not conducive to blocking diffusion of nitrogen atoms in the nitrogen-containing dielectric layer <NUM> to the metal conductive layer <NUM>; and when the atomic ratio of nitrogen atoms is too large, it is likely to cause the second molybdenum nitride layer <NUM> to become a contamination source of nitrogen atoms, that is, the nitrogen atoms in the second molybdenum nitride layer <NUM> diffuse into the metal conductive layer <NUM>.

It can be understood that when the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is set to be large, the second molybdenum nitride layer <NUM> can block the nitrogen atoms in the nitrogen-containing dielectric layer <NUM> through two mechanisms, which are specifically explained as follows. First, when the atomic ratio of nitrogen atoms is large, the distance between neighboring atoms is small and it is not easy for the nitrogen atoms to pass through. Second, when the atomic ratio of nitrogen atoms is large, the doping concentration of the nitrogen atoms is high (a nitride can be understood as doping nitrogen atoms in another kind of atoms), the doping concentration of the nitrogen atoms in the second molybdenum nitride layer <NUM> is higher than or equal to the doping concentration of the nitrogen atoms in the nitrogen-containing dielectric layer <NUM>, or, the difference between the doping concentration of the nitrogen atoms in the second molybdenum nitride layer <NUM> and the doping concentration of the nitrogen atoms in the nitrogen-containing dielectric layer <NUM> is small, which is conducive to avoiding the nitrogen atoms in the nitrogen-containing dielectric layer <NUM> from diffusing into the metal conductive layer <NUM> based on the concentration difference.

In this embodiment, as the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> changes, the thickness of the second molybdenum nitride layer <NUM> changes, so as to ensure that the blocking performance of the second molybdenum nitride layer <NUM> is higher than a preset level. Exemplarily, the thickness of the second molybdenum nitride layer <NUM> is <NUM> to <NUM>, for example, <NUM>, <NUM> or <NUM>, in the direction from the doped conductive layer <NUM> to the nitrogen-containing dielectric layer <NUM>. When the thickness of the second molybdenum nitride layer <NUM> is too large, it is not conducive to thinning the entire semiconductor structure, and may cause the second molybdenum nitride layer <NUM> to become a nitrogen atom source, i.e., the nitrogen atoms included in the second molybdenum nitride layer <NUM> diffuse into the metal conductive layer <NUM>; and when the thickness of the second molybdenum nitride layer <NUM> is too small, it is not conducive to blocking the nitrogen atoms in the nitrogen-containing dielectric layer <NUM> from diffusing into the metal conductive layer <NUM>.

In this embodiment, the material of the metal conductive layer <NUM> includes metal molybdenum. Compared with metal tungsten, metal molybdenum is less prone to lateral etching during an etching process, which is conducive to ensuring that each discrete metal conductive layer <NUM> formed by patterned etching has a preset lateral effective width d, so that the metal conductive layer <NUM> has a small resistance.

In this embodiment, the metal conductive layer <NUM> is composed of a single metal material. In this case, the first molybdenum nitride layer <NUM>, the metal conductive layer <NUM>, and the second molybdenum nitride layer <NUM> can be continuously formed in a same reaction chamber, without interrupting the manufacturing process to adjust the metal source, which is conducive to avoiding a vacuum environment from being destroyed to cause the surface of the film layer to be oxidized and is conducive to ensuring the continuity between different film layers. It can be understood that if the metal conductive layer <NUM> further includes other metal materials, it is required to perform a cleaning process or change the chamber after forming the metal conductive layer <NUM>, so as to avoid the other metal materials left in the reaction chamber from contaminating the second molybdenum nitride layer <NUM>.

In this embodiment, the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM> each include a molybdenum nitride material having a polycrystalline structure. Exemplarily, the molybdenum nitride material having a polycrystalline structure includes polycrystalline γ-Mo<NUM>N. Furthermore, the crystallinity of the molybdenum nitride material in the first molybdenum nitride layer <NUM> is greater than the crystallinity of the molybdenum nitride material in the second molybdenum nitride layer <NUM>. It should be noted that the larger the atomic ratio of nitrogen atoms, the more difficult it is to crystallize a molybdenum nitride material having an amorphous structure. Before crystallization, if the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM> each include a molybdenum nitride material having an amorphous structure, under a same crystallization condition, the crystallinity of the molybdenum nitride material in the first molybdenum nitride layer <NUM> is greater than the crystallinity of the molybdenum nitride material in the second molybdenum nitride layer <NUM>. The higher the crystallinity, the larger the size of the crystal particles, the smaller the number of the crystal boundaries, the more regular the arrangement of the crystal particles, the smaller the sheet resistance of the molybdenum nitride material. The greater crystallinity of the molybdenum nitride material in the first molybdenum nitride layer <NUM> is conducive to ensuring that the first molybdenum nitride layer <NUM> has higher signal transmission performance.

In this embodiment, by controlling the atomic ratio of nitrogen atoms in the first molybdenum nitride layer to be smaller the sheet resistance of the material of the first molybdenum nitride layer is decreased, which is conducive to a small series resistance between the doped conductive layer and the metal conductive layer, and ensuring that the first molybdenum nitride layer not only can block mutual migration and penetration between the metal atoms and the dopant ions, but also has little influence on electrical connection performance between the metal conductive layer and the doped conductive layer. Meanwhile, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer is controlled to be larger, which is conducive to enabling strong blocking performance of the second molybdenum nitride layer, better blocking migration of nitrogen atoms in the nitrogen-containing dielectric layer to the metal conductive layer, and ensuring that the metal conductive layer has better conductive characteristics.

Correspondingly, embodiments of this disclosure further provide a method for manufacturing a semiconductor structure, which can be configured to manufacture the foregoing semiconductor structure.

<FIG> are schematic structural diagrams corresponding to various operations of a method for manufacturing a semiconductor structure provided in embodiments of this disclosure. The method for manufacturing a semiconductor structure includes the following operations.

Referring to <FIG>, a doped conductive layer <NUM> and a first molybdenum nitride layer <NUM> are formed, where the doped conductive layer <NUM> is doped with dopant ions, and the first molybdenum nitride layer <NUM> is located on the doped conductive layer <NUM>.

In this embodiment, the doped conductive layer <NUM> is connected to an active area <NUM> at the bottom, and an isolation structure 20a surrounds the active area <NUM> and is configured to isolate neighboring active areas <NUM>. The process of forming the first molybdenum nitride layer <NUM> includes the following. A nitrogen source gas and metal molybdenum are introduced. An ionization process is performed to form nitrogen plasma, so that the nitrogen plasma reacts with the metal molybdenum to produce molybdenum nitride, and the molybdenum nitride is deposited to form a molybdenum nitride layer, which has an amorphous structure. The metal molybdenum may be fed using an inert gas, the nitrogen source gas includes nitrogen, and the inert gas includes argon.

Referring to <FIG>, a metal conductive layer <NUM> and a second molybdenum nitride layer <NUM> are formed, where the metal conductive layer <NUM> is located on the first molybdenum nitride layer <NUM>, the first molybdenum nitride layer <NUM> is configured to be electrically connected to the doped conductive layer <NUM> and the metal conductive layer <NUM>, the second molybdenum nitride layer <NUM> is located on the metal conductive layer <NUM>, and an atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is greater than an atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>.

In this embodiment, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is greater than the atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>, the blocking performance of the material of the second molybdenum nitride layer <NUM> is higher than the blocking performance of the material of the first molybdenum nitride layer <NUM>. In order to enable the first molybdenum nitride layer <NUM> to have a strong blocking effect, it is required to configure that the thickness of the first molybdenum nitride layer <NUM> is greater than the thickness of the second molybdenum nitride layer <NUM> in a direction from the doped conductive layer <NUM> to the second molybdenum nitride layer <NUM>.

In this embodiment, the process step of forming the first molybdenum nitride layer <NUM> and the process step of forming the second molybdenum nitride layer <NUM> are identical, and are merely different from each other in that the flow rate of the nitrogen source gas for forming the first molybdenum nitride layer <NUM> is smaller than the flow rate of the nitrogen source gas for forming the second molybdenum nitride layer <NUM>, such that the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is greater than the atomic ratio of nitrogen atoms in the first molybdenum nitride layer <NUM>.

Further, in the processes of forming the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM>, the ratios of the flow rates of the nitrogen source gases to the sums of the flow rates of the nitrogen source gases and the inert gases are identical, and the process temperatures are identical, which are conducive to enabling the performance, other than the atomic ratio, of the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM> to be similar. Exemplarily, during the process of forming the first molybdenum nitride layer <NUM>, the flow rate of the nitrogen source gas is <NUM> sccm, the flow rate of the inert gas is <NUM> sccm, the ratio of the flow rates is <NUM>%, and the process temperature is <NUM>; and in the process of forming the second molybdenum nitride layer <NUM>, the flow rate of the nitrogen source gas is <NUM> sccm, the flow rate of the inert gas is <NUM> sccm, the ratio of the flow rates maintains <NUM>%, and the process temperature maintains <NUM>.

In this embodiment, the ionization process of forming the first molybdenum nitride layer <NUM> is denoted as a first ionization process, and the ionization process of forming the second molybdenum nitride layer <NUM> is denoted as a second ionization process. Since the thickness of the first molybdenum nitride layer <NUM> is greater than the thickness of the second molybdenum nitride layer <NUM> in the case that blocking performances are similar, specific parameters of the first ionization process and specific parameters of the second ionization process are different. Specifically, since the higher the direct-current power supply power, the greater the speed of reaction between the nitrogen plasma and the metal molybdenum, and the greater the deposition speed of the molybdenum nitride layer, it is available to configure that the direct-current power supply power of the first ionization process is higher than or equal to the direct-current power supply power of the second ionization process, such that the time spent to manufacture the first molybdenum nitride layer <NUM> is shorter. Correspondingly, since the higher the radio frequency bias power, the better the film layer uniformity, and the requirement for the film layer uniformity of a thick film layer is lower, it is available to configure that the radio frequency bias power of the first ionization process is lower than or equal to the radio frequency bias power of the second ionization process, such that the second molybdenum nitride layer <NUM> has higher film layer uniformity, i.e., the second molybdenum nitride layer <NUM> has good blocking performance.

It is available to configure that the direct-current power supply power of the first ionization process is <NUM> W to <NUM> W, for example, <NUM> W, <NUM> W or <NUM> W, and the direct-current power supply power of the second ionization process is <NUM> W to <NUM> W, for example, <NUM> W, <NUM> W or <NUM> W. When the direct-current power supply power is high, it is likely to cause a fast deposition speed of the molybdenum nitride layer, and thus it is not easy to precisely control the thicknesses of the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM>; and when the direct-current power supply power is low, it is likely to cause a slow deposition speed of the molybdenum nitride layer, which is not conducive to shortening the overall manufacturing duration. Correspondingly, it is available to configure that the radio frequency bias power of the first ionization process is <NUM> W to <NUM> W, for example, <NUM> W, <NUM> W, <NUM> W or <NUM> W, and to configure that the radio frequency bias power of the second ionization process is <NUM> W to <NUM> W, for example, <NUM> W, <NUM> W or <NUM> W. When the radio frequency bias power is high, it is not conducive to reducing the process power consumption and the process cost; and when the radio frequency bias power is low, it is not conducive to improving the uniformity and compactness of the molybdenum nitride layer.

Referring to <FIG> and <FIG>, a nitrogen-containing dielectric layer <NUM> is formed, and is located on the second molybdenum nitride layer <NUM>, and a patterned etching process is performed to form multiple discrete semiconductor structures, where the semiconductor structure may be a bit line structure.

In this embodiment, since the nitrogen-containing dielectric layer <NUM> is grown in a thermal treatment process environment, under the effect of the high-temperature process, at least parts of the amorphous structures in the molybdenum nitride layers (i.e., the first molybdenum nitride layer <NUM> and the second molybdenum nitride layer <NUM>) will be converted into the polycrystalline structures. Meanwhile, since the atomic ratio of nitrogen atoms in the second molybdenum nitride layer <NUM> is larger, the crystallinity of the molybdenum nitride material in the second molybdenum nitride layer <NUM> is lower. In other embodiments, after the second molybdenum nitride layer is formed, the thermal treatment process is performed, so that at least part of the amorphous structure in the molybdenum nitride layer is converted into the polycrystalline structure, or, after the nitrogen-containing dielectric layer <NUM> is formed, at least part of the amorphous structure is converted into the polycrystalline structure using other thermal treatment processes.

In this embodiment, the metal conductive layer <NUM> is a metal molybdenum layer, and the first molybdenum nitride layer <NUM>, the second molybdenum nitride layer <NUM>, and the metal molybdenum layer are formed in a same reaction chamber.

In the foregoing technical solution, the atomic ratio of nitrogen atoms in the first molybdenum nitride layer is controlled to be smaller, thereby decreasing the sheet resistance of the material of the first molybdenum nitride layer, enabling a small series resistance between the doped conductive layer and the metal conductive layer, and ensuring that the first molybdenum nitride layer not only can block mutual migration and penetration between metal atoms and the dopant ions, but also has little influence on electrical connection performance between the metal conductive layer and the doped conductive layer. Meanwhile, the atomic ratio of nitrogen atoms in the second molybdenum nitride layer is controlled to be larger, which is conducive to enabling strong blocking performance of the second molybdenum nitride layer, better blocking migration of nitrogen atoms in the nitrogen-containing dielectric layer to the metal conductive layer, and ensuring that the metal conductive layer has a better conductive characteristic.

It can understand by persons of ordinary skill in the art that the above-mentioned implementations are specific embodiments for implementing this disclosure, and in practical applications, various changes may be made in form and detail without departing from the scope of this disclosure.

Claim 1:
A semiconductor structure, comprising:
a doped conductive layer (<NUM>), doped with dopant ions;
a metal conductive layer (<NUM>), located above the doped conductive layer (<NUM>);
a nitrogen-containing dielectric layer (<NUM>), located above the metal conductive layer (<NUM>);
a first molybdenum nitride layer (<NUM>), located between the doped conductive layer (<NUM>) and the metal conductive layer (<NUM>) and electrically connected to the doped conductive layer (<NUM>) and the metal conductive layer (<NUM>); and
a second molybdenum nitride layer (<NUM>), located between the metal conductive layer (<NUM>) and the nitrogen-containing dielectric layer (<NUM>),
characterized in that an atomic ratio of nitrogen atoms in the second molybdenum nitride layer (<NUM>) is greater than an atomic ratio of nitrogen atoms in the first molybdenum nitride layer (<NUM>).