Low-dielectric silicon nitride film and preparation method and application thereof

Abstract

The invention belongs to the technical field of semiconductor materials, and particularly relates to a low-dielectric silicon nitride film and a preparation method and application thereof. The preparation method of the low-dielectric silicon nitride film comprises the following steps: S1, introducing an organic amino silane precursor into a reaction chamber, and performing atomic layer deposition on the surface of a substrate to obtain a first reactant; s2, an auxiliary agent is introduced into the reaction chamber to be subjected to a contact reaction with the first reactant, and a second reaction product is obtained; and S3, introducing a plasma source-containing gas into the reaction chamber, and carrying out contact reaction on the plasma source-containing gas and the second reaction product to obtain the low-dielectric silicon nitride film, wherein the auxiliary agent is a nitrogen-containing MOF material. The preparation method is characterized in that a nitrogen-containing MOF material is introduced as a sacrificial template assistant to react with an organic amino silane precursor, so that metal and carbon can be uniformly doped into the silicon nitride film, and the prepared silicon nitride film has the properties of low dielectric constant, low density and reduction of wet etching rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials, and in particular relates to a low-dielectric silicon nitride film and a preparation method and application thereof. Background Art

[0002] Organoaminosilanes are a class of organic silicon compounds containing silicon and nitrogen elements. They usually have the following structural characteristics: a silicon atom (Si) is connected to one or more organic groups (R) and amino groups (NH2 or NR2). Organoaminosilanes are often used as precursor materials to manufacture silicon-based semiconductor thin film materials such as silicon oxide, silicon nitride and silicon carbide through atomic layer deposition (ALD), chemical vapor deposition (CVD), cyclic chemical vapor deposition (CCVD), plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD) or liquid-based deposition processes (spin coating, dip coating, aerosol, inkjet, screen printing, spray deposition and other technologies). These silicon-based semiconductor thin film materials have a wide range of applications in high-end capacitors, solar cells, memory devices, lasers, light-emitting diodes and gas sensors due to their unique physical and chemical properties.

[0003] At present, although the technology of preparing silicon nitride film using organic aminosilane as precursor is quite mature, it still faces some challenges, such as side reactions that are prone to occur during the deposition process, causing the film to be doped with impurities, reducing purity, and affecting the quality and performance of the silicon nitride film. In addition, since the silicon nitride film prepared by the existing method generally has a high dielectric constant, it is not conducive to compatibility with other materials to realize complex integrated circuit design, and it will reduce the conductivity of the device and is not conducive to the application of electronic transmission devices. At the same time, it is necessary to control the wet etching rate of the silicon nitride film to achieve high-performance semiconductor device manufacturing. Therefore, it is necessary to improve the existing silicon nitride film preparation method to achieve the preparation of silicon nitride film with low dielectric constant, low density and low wet etching rate. Summary of the invention

[0004] The purpose of the present invention is to provide a carbon and metal co-doped silicon nitride film and its preparation method and application to address the shortcomings of the silicon nitride films prepared by the prior art, which generally have a high dielectric constant and cannot meet the application requirements of certain specific scenarios. A silicon nitride film with low dielectric constant, low density and low wet etching rate is obtained to realize the preparation and application of high-performance semiconductor devices.

[0005] In a first aspect, the present invention provides a method for preparing a low dielectric silicon nitride film, which comprises the following steps: S1. introducing an organic aminosilane precursor into a reaction chamber, and obtaining a first reactant on a substrate surface by atomic layer deposition; S2. introducing an auxiliary agent into the reaction chamber to contact and react with the first reactant to obtain a second reaction product; S3. introducing a plasma source gas into the reaction chamber to contact and react with the second reaction product to obtain a low dielectric silicon nitride film; the auxiliary agent is a nitrogen-containing MOF material.

[0006] In a preferred embodiment, the temperature of the reaction chamber is 100-400° C., and the pressure is 100-500 Pa.

[0007] In a preferred embodiment, the substrate is selected from at least one of silicon wafer, quartz, glass and resin.

[0008] In a preferred embodiment, the method of introducing the organoaminosilane precursor into the reaction chamber includes: introducing the organoaminosilane precursor into the reaction chamber in a pulsed form with the aid of carrier gas I.

[0009] In a preferred embodiment, the carrier gas I is selected from at least one of nitrogen, argon, helium and krypton.

[0010] In a preferred embodiment, the flow rate of the carrier gas I is 50-300 sccm.

[0011] In a preferred embodiment, the pulse duration is 1 to 10 seconds.

[0012] In a preferred embodiment, the method of introducing the auxiliary agent into the reaction chamber includes: the auxiliary agent is introduced into the reaction chamber in a pulsed form with the aid of carrier gas II.

[0013] In a preferred embodiment, the carrier gas II is selected from at least one of nitrogen, argon, helium and krypton.

[0014] In a preferred embodiment, the flow rate of the carrier gas I is 50-300 sccm.

[0015] In a preferred embodiment, the pulse duration is 1 to 10 seconds.

[0016] In a preferred embodiment, the chemical formula of the organoaminosilane is (NR1R2) y S H x (R3) z, wherein x, y, and z are all integers and 0≤x≤3, 0≤y≤3, 0≤z≤3, x+y+z=4, R1 and R2 are each independently selected from H or a C1-C5 alkyl group, R3 is selected from any one of -SiR4R5R6, -NH-CH3, -NH-CH2CH3, -N(CH3)2, -(NH)2-CH3, -(NH)2-CH2CH3, -NH-(CH2)2CH3, and -NH-CH(CH3)2, and R4, R5, and R6 are each independently selected from any one of H, -CH3, -NH-CH3, -NH-CH2CH3, -N(CH3)2, -(NH)2-CH3, -(NH)2-CH2CH3, -NH-(CH2)2CH3, and -NH-CH(CH3)2.

[0017] In a preferred embodiment, the ligand in the nitrogen-containing MOF material is selected from at least one of imidazole ligands, porphyrin ligands and pyridine ligands.

[0018] In a preferred embodiment, the nitrogen-containing MOF material is selected from at least one of ZIF-8, ZIF-67, copper-based PCN-222, zirconium-based PCN-222, iron-based PCN-250, manganese-based PCN-222, indium-based USTC-8, and Mn-AdDB.

[0019] In a preferred embodiment, the plasma source gas is selected from at least one of nitrogen and argon plasma, nitrogen and helium plasma, ammonia plasma, nitrogen and ammonia plasma, ammonia and helium plasma, ammonia and argon plasma and NF3-containing plasma.

[0020] In a preferred embodiment, the preparation method comprises repeating steps S1 to S3 at least once.

[0021] In a second aspect, the present invention provides a low dielectric silicon nitride film prepared by the above method.

[0022] In a preferred embodiment, the metal content in the silicon nitride film is 5-10 wt %.

[0023] In a preferred embodiment, the carbon content in the silicon nitride film is 23-31 wt %.

[0024] In a third aspect, the present invention also provides applications of the low dielectric silicon nitride film in the semiconductor industry.

[0025] The key to the present invention is to introduce nitrogen-containing MOF materials to react with organic aminosilane precursors, which is beneficial to uniformly doping metals and carbon into silicon nitride films and increasing the nitrogen content of silicon nitride films. The metal and carbon co-doped silicon nitride films prepared by atomic layer deposition-plasma reaction (PE-ALD) have low dielectric constant, low density and reduced wet etching rate. In practical applications, the compatibility of silicon nitride films with other materials can be improved to achieve the manufacture of high-performance semiconductor devices. DETAILED DESCRIPTION

[0026] The preparation method of the low dielectric silicon nitride film provided by the present invention comprises the following steps: S1. introducing an organic aminosilane precursor into a reaction chamber, and obtaining a first reactant on a substrate surface by atomic layer deposition; S2. introducing an auxiliary agent into the reaction chamber to contact and react with the first reactant to obtain a second reaction product; S3. introducing a plasma source gas into the reaction chamber to contact and react with the second reaction product to obtain a low dielectric silicon nitride film.

[0027] In the present invention, the temperature of the reaction chamber is preferably 100-400°C, such as 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C or any value therebetween; the pressure is preferably 100-500Pa, such as 100Pa, 200Pa, 300Pa, 400Pa, 500Pa or any value therebetween.

[0028] In the present invention, in step S1, the method of introducing the organoaminosilane precursor into the reaction chamber preferably includes: the organoaminosilane precursor is introduced into the reaction chamber in the form of pulses with the aid of carrier gas I. Wherein, the flow rate of the carrier gas I is preferably 50 to 300 sccm, such as 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm or any value therebetween. The pulse time is preferably 1 to 10 s, such as 1 s, 2 s, 5 s, 8 s, 10 s or any value therebetween. After the organoaminosilane precursor is introduced into the reaction chamber, it may also include introducing carrier gas I for purging. The purging time is preferably 10 to 60 s, such as 10 s, 20 s, 30 s, 40 s, 50 s, 60 s or any value therebetween.

[0029] In the present invention, in step S2, the preferred manner of introducing the auxiliary agent into the reaction chamber includes: the auxiliary agent is introduced into the reaction chamber in the form of pulses with the aid of carrier gas II. Wherein, the flow rate of the carrier gas II is preferably 50 to 300 sccm, such as 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm or any value therebetween. The pulse time is preferably 1 to 10 s, such as 1 s, 2 s, 5 s, 8 s, 10 s or any value therebetween. After the auxiliary agent is introduced into the reaction chamber, it may also include introducing carrier gas II for purging. The purging time is preferably 10 to 60 s, such as 10 s, 20 s, 30 s, 40 s, 50 s, 60 s or any value therebetween. The carrier gas I and the carrier gas II are both inert gases, and are each independently selected from at least one of nitrogen, argon, helium and krypton.

[0030] In a specific embodiment, the method for preparing the low dielectric silicon nitride film may include the following steps: S1. Placing a substrate in a reaction chamber, setting the temperature of the reaction chamber to 100-400°C and the pressure to 100-500 Pa, introducing an organic aminosilane precursor into the reaction chamber in a pulsed form with the aid of carrier gas I, and using an atomic layer deposition method to allow the organic aminosilane precursor to chemically adsorb on the surface of the substrate to obtain a first reactant; S2. Introducing an auxiliary agent into the reaction chamber in a pulsed form with the aid of carrier gas II, allowing the auxiliary agent to contact and react with the first reactant to obtain a second reaction product; S3. Introducing a plasma source gas into the reaction chamber to allow the auxiliary agent to contact and react with the second reaction product to obtain a low dielectric silicon nitride film.

[0031] In the present invention, the organoaminosilane can be any silane compound having an amino group, preferably having a chemical formula (NR1R2): y S H x (R3) zA class of compounds of the structure shown, whose specific types and sources are not limited, can be obtained from commercial sources or prepared by existing methods. Wherein, x, y, z are all integers and 0≤x≤3, x can be 0, 1, 2 or 3, 0≤y≤3, y can be 0, 1, 2 or 3, 0≤z≤3, z can be 0, 1, 2 or 3, x+y+z=4; R1 and R2 are each independently selected from H or C1~C5 alkyl; R3 is selected from any one of -SiR4R5R6, -NH-CH3 (methylamino), -NH-CH2CH3 (ethylamino), -N(CH3)2 (dimethylamino), -(NH)2-CH3 (methyldiamino), -(NH)2-CH2CH3 (ethyldiamino), -NH-(CH2)2CH3 (n-propylamino), -NH-CH(CH3)2 (isopropylamino). Specific examples of the C1-C5 alkyl group include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. R4, R5 and R6 are each independently preferably selected from any one of H, -CH3, -NH-CH3, -NH-CH2CH3, -N(CH3)2, -(NH)2-CH3, -(NH)2-CH3CH2, -NH-(CH2)2CH3, and -NH-CH(CH3)2. -SiR4R5R6 can be exemplarily selected from any one of -SiH2CH3 (methylsilyl), -SiH(CH3)2 (dimethylsilyl), -Si(CH3)3 (trimethylsilyl), -Si(NH2)3 (triaminosilyl), -SiCH3(NH2)2 (diaminomethylsilyl), -Si(CH3)2NH2 (aminodimethylsilyl), -SiHCH3NH2 (aminomethylsilyl), -SiH(NHCH3)2 (di(methylamino)silyl), and -Si{(NH)2CH3}3 (tri(methyldiamino)silyl).

[0032] In the present invention, the organic aminosilane is preferably selected from methylaminosilane, ethyldiaminosilane, n-propylaminosilane, isopropylaminosilane, bis(methylamino)silane, bis(methyldiamino)silane, bis(ethyldiamino)silane, bis(n-propylamino)silane, di(isopropylamino)silane, tris(ethylamino)silane, tris(ethyldiamino)silane, tris(n-propylamino)silane, tris(isopropylamino)silane, dimethylaminosilane, diethylaminosilane, di-n-propylaminosilane, di-n-butylaminosilane, di-tert-butylaminosilane, di(dimethylamino)silane, di(di-n-propylamino)silane, di(diisopropylamino)silane, di(di-n-butylamino)silane, di(di-tert-butylamino)silane, tris(dimethylamino)silane, tris(diethyl ... amine) silane, tris(di-n-propylamine) silane, tris(diisopropylamine) silane, tris(diisobutylamine) silane, tris(di-tert-butylamine) silane, methylamino-dimethylamine silane, ethyldiamino-di-n-propylamine silane, ethyldiamino-diisopropylamine silane, ethyldiamino-diisobutylamine silane, n-propylamino-di(di-n-butylamine) silane, n-propylamino-di(diisobutylamine) silane, n-propylamino-tris(dimethylamine) silane, n-propylamino-tris(diethylamine) silane, bis(methylamino)-di(dimethylamine) silane, bis(methylamino)-di(diethylamine) silane, bis(methylamino)-di(diisopropylamine) silane, bis(methylamino)-di(di-n-butylamine) silane, bis(methylamino) )-bis(diisobutylamine)silane, bis(methyldiamino)-di-tert-butylaminesilane, bis(methyldiamino)-bis(dimethylamine)silane, bis(methyldiamino)-bis(diethylamine)silane, tris(ethylamino)-di-n-butylaminesilane, tris(ethylamino)-diisobutylaminesilane, tris(methyldiamino)-diethylaminesilane, tris(methyldiamino)-di-n-propylaminesilane, trisamino-methylbissilane (CH3-SiH2-Si(NH2)3), methyldiaminobissilane (SiH3-Si{(NH)2CH3}2), di(methylamino)-di(ethylamine)bissilane ((CH3NH)2-SiH-SiH-(NHCH2CH3)2), di(methylamino)-di(isobutylamine)silane 2-propylamine)bissilane ((CH3NH)2-SiH-SiH-{NHCH(CH3)2}2), bis(methylamino)-bis(isobutylamine)bissilane ((CH3NH)2-SiH-SiH-{NHCH2CH(CH3)2}2), bis(methylamino)-bis(tert-butylamine)bissilane ((CH3NH)2-SiH-SiH-{NHC(CH3)3}2), tris(methyldiamino)-bis(ethylamine)bissilane ({CH3(NH)2}3-Si-SiH-(NHCH2CH3)2), tris(methyldiamino)-bis(n-propylamine)bissilane ({CH3(NH)2}3-Si-SiH-(NHCH2CH2CH3)2),At least one of trimethylsilyl-diisobutylamine silane, trimethylsilyl-di-tert-butylamine silane, trimethylsilyl-dimethylamine silane, trimethylsilyl-di-n-propylamine silane, trimethylsilyl-diisopropylamine silane, and trimethylsilyl-di-n-butylamine silane.

[0033] In the present invention, the auxiliary agent is a nitrogen-containing MOF material. The nitrogen-containing MOF material is a polymer material composed of a nitrogen-containing organic ligand and a metal center. The nitrogen-containing organic ligand is preferably selected from at least one of imidazole ligands, porphyrin ligands, pyridine ligands and 2-aminoterephthalic acid, and more preferably at least one of imidazole ligands, porphyrin ligands and pyridine ligands. At this time, it is more conducive to increasing the metal, carbon and nitrogen content of the silicon nitride film, and is more conducive to obtaining a silicon nitride film with a low dielectric constant, low density and reduced wet etching rate. Specific examples of the nitrogen-containing MOF material include but are not limited to: at least one of ZIF-8, ZIF-67, copper-based PCN-222, zirconium-based PCN-222, iron-based PCN-250, manganese-based PCN-222, indium-based USTC-8, and Mn-AdDB.

[0034] In the present invention, the preparation method preferably includes repeating steps S1 to S3 at least once. Taking steps S1 to S3 as one cycle, a silicon nitride film of a certain thickness is obtained by repeating steps S1 to S3. The number of repetitions of steps S1 to S3 can be determined according to the thickness of the target silicon nitride film.

[0035] In the present invention, the metal content in the low dielectric silicon nitride film is preferably 5-10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or any value therebetween. The carbon content in the low dielectric silicon nitride film is preferably 23-31wt%, such as 23wt%, 25wt%, 28wt%, 30wt%, 31wt% or any value therebetween.

[0036] The present invention will be described in detail below through specific embodiments.

[0037] Example 1

[0038] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and introduce diisopropylaminosilane (DIPAS) into the reaction chamber in the form of pulses for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0039] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0040] S3. Nitrogen plasma gas is introduced into the reaction chamber at a flow rate of 150 sccm for 30 seconds, and steps S1 to S3 are repeated 200 times to obtain a carbon and zinc co-doped silicon nitride film.

[0041] Example 2

[0042] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 300°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0043] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0044] S3. Nitrogen plasma gas is introduced into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds. Steps S1 to S3 are repeated 200 times to obtain a carbon-zinc co-doped silicon nitride film.

[0045] Example 3

[0046] S1. Place the substrate in a reaction chamber, set the temperature of the reaction chamber to 250°C and the pressure to 150 Pa, then introduce nitrogen as a carrier gas, with a gas flow rate of 150 sccm, introduce bis(methylamino)-bis(diisobutylamino)silane having a chemical formula of (CH3NH)2Si(NHCH(CH3)3)2 into the reaction chamber in the form of pulses, and introduce the bis(methylamino)-bis(diisobutylamino)silane into the reaction chamber for 3 seconds to allow the precursor to chemically adsorb onto the substrate, and then introduce nitrogen for 30 seconds to obtain a first reactant;

[0047] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0048] S3. Nitrogen plasma gas is introduced into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds. Steps S1 to S3 are repeated 200 times to obtain a carbon-zinc co-doped silicon nitride film.

[0049] Example 4

[0050] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150 Pa, then introduce argon as a carrier gas, the gas flow rate is 150 sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3 seconds to allow the precursor to chemically adsorb on the substrate, and then introduce argon for 30 seconds to obtain a first reactant;

[0051] S2. ZIF-8 was introduced into the reaction chamber in the form of pulses with argon as carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0052] S3. Introduce nitrogen plasma gas into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds, and repeat steps S1 to S3 200 times in sequence to obtain a carbon and zinc co-doped silicon nitride film.

[0053] Example 5

[0054] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0055] S2. PCN-222 (Zr) was introduced into the reaction chamber in the form of pulses with nitrogen as carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0056] S3. Introduce nitrogen plasma gas into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds, and repeat steps S1 to S3 200 times in sequence to obtain a carbon and zirconium co-doped silicon nitride film.

[0057] Example 6

[0058] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0059] S2. Mn-AdDB was introduced into the reaction chamber in a pulsed manner using nitrogen as a carrier gas, with a gas flow rate of 200 sccm and an introduction time of 5 s, so that the auxiliary agent fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain the second reactant; (wherein, Mn-AdDB was prepared according to the method in the literature DOI: https: / / doi.org / 10.1002 / ange.202205238)

[0060] S3. Introduce nitrogen plasma gas into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds, and repeat steps S1 to S3 200 times in sequence to obtain a carbon and manganese co-doped silicon nitride film.

[0061] Example 7

[0062] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 200sccm, and introduce di(dimethylamino)silane into the reaction chamber in the form of pulses for 5s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0063] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0064] S3. Nitrogen plasma gas is introduced into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds. Steps S1 to S3 are repeated 200 times to obtain a carbon-zinc co-doped silicon nitride film.

[0065] Example 8

[0066] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0067] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 250 sccm, the introduction time was 7 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0068] S3. Nitrogen plasma gas is introduced into the reaction chamber with a nitrogen flow rate of 150 sccm for 30 seconds. Steps S1 to S3 are repeated 200 times to obtain a carbon-zinc co-doped silicon nitride film.

[0069] Example 9

[0070] S1. Place the substrate in a reaction chamber, set the reaction chamber temperature to 250°C, the pressure to 150Pa, then introduce nitrogen as a carrier gas, the gas carrier flow rate is 150sccm, and diisopropylaminosilane (DIPAS) is introduced into the reaction chamber in the form of a pulse for 3s to allow the precursor to chemically adsorb on the substrate, and then introduce nitrogen for 30s to obtain a first reactant;

[0071] S2. The ZIF-8 was introduced into the reaction chamber in the form of a pulse with nitrogen as the carrier gas, the gas carrier flow rate was 200 sccm, the introduction time was 5 s, the additive was fully reacted with the first reactant, and then nitrogen was introduced for 30 s to obtain a second reactant;

[0072] S3. Introduce nitrogen plasma gas into the reaction chamber with a nitrogen flow rate of 200 sccm for 45 seconds, and repeat steps S1 to S3 200 times in sequence to obtain a carbon-zinc co-doped silicon nitride film.

[0073] Example 10

[0074] A silicon nitride film was prepared according to the method of Example 1, except that ZIF-67 was used instead of ZIF-8. The other conditions were the same as those of Example 1, thereby preparing a carbon and cobalt co-doped silicon nitride film.

[0075] Embodiment 11

[0076] A silicon nitride film was prepared according to the method of Example 1, except that UiO-66-NH2(Zr) was used instead of ZIF-8. The other conditions were the same as those of Example 1, thereby preparing a carbon and zirconium co-doped silicon nitride film.

[0077] Comparative Example 1

[0078] A reference silicon nitride thin film was prepared according to the method of Example 1, except that triethylamine was used instead of ZIF-8. The other conditions were the same as those of Example 1, thereby preparing a reference silicon nitride thin film.

[0079] Comparative Example 2

[0080] A reference silicon nitride film was prepared according to the method of Example 1, except that tris(dimethylamino)aluminum was used instead of ZIF-8. The other conditions were the same as those of Example 1, thereby preparing a reference silicon nitride film.

[0081] Test Case

[0082] The silicon nitride films prepared in the above examples and comparative examples were tested for dielectric constant, wet etching rate, density, and element content (metal, C, N) according to the following method. The results are shown in Table 1.

[0083] (1) Dielectric constant test: The test method is the resonant cavity method. The sample is cut into 80 mm × 80 mm squares and the dielectric constant is measured using a dielectric constant tester at a frequency of 0.6 GHz.

[0084] (2) Wet etching rate test: A hydrofluoric acid (HF) solution with a mass fraction of 0.5 wt% was prepared with deionized water, and the silicon nitride film was wet-etched with the solution. The wet etching rate was calculated by (etched film thickness divided by etching time).

[0085] (3) Density test: using an X-ray reflectometer (XRR, model Malvern Panalytical X'

[0086] The density of the film was tested by PertPRO.

[0087] (4) Element content test: The element composition and content of the film were tested using an XPS tester (ThermoFisher EscaLab Xi+).

[0088] Table 1

[0089]

[0090] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for preparing a low dielectric silicon nitride film, characterized in that: The preparation method comprises the following steps: S1. introducing an organic aminosilane precursor into a reaction chamber, and obtaining a first reactant on a substrate surface by atomic layer deposition; S2. introducing an auxiliary agent into the reaction chamber to contact and react with the first reactant to obtain a second reaction product; S3. introducing a plasma source gas into the reaction chamber to contact and react with the second reaction product to obtain a low dielectric silicon nitride film; the auxiliary agent is a nitrogen-containing MOF material.

2. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The temperature of the reaction chamber is 100-400°C and the pressure is 100-500Pa; Preferably, the substrate is selected from at least one of silicon wafer, quartz, glass and resin.

3. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The method of introducing the organoaminosilane precursor into the reaction chamber includes: introducing the organoaminosilane precursor into the reaction chamber in the form of pulses with the aid of carrier gas I; Preferably, the carrier gas I is selected from at least one of nitrogen, argon, helium and krypton; Preferably, the flow rate of the carrier gas I is 50 to 300 sccm; Preferably, the pulse duration is 1 to 10 seconds.

4. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The method of introducing the auxiliary agent into the reaction chamber includes: introducing the auxiliary agent into the reaction chamber in the form of pulses with the aid of carrier gas II; Preferably, the carrier gas II is selected from at least one of nitrogen, argon, helium and krypton; Preferably, the flow rate of the carrier gas I is 50 to 300 sccm; Preferably, the pulse duration is 1 to 10 seconds.

5. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The chemical formula of the organoaminosilane is (NR1R2) y S H x (R3) z , wherein x, y, and z are all integers and 0≤x≤3, 0≤y≤3, 0≤z≤3, x+y+z=4, R1 and R2 are each independently selected from H or a C1-C5 alkyl group, R3 is selected from any one of -SiR4R5R6, -NH-CH3, -NH-CH2CH3, -N(CH3)2, -(NH)2-CH3, -(NH)2-CH2CH3, -NH-(CH2)2CH3, and -NH-CH(CH3)2, and R4, R5, and R6 are each independently selected from any one of H, -CH3, -NH-CH3, -NH-CH2CH3, -N(CH3)2, -(NH)2-CH3, -(NH)2-CH2CH3, -NH-(CH2)2CH3, and -NH-CH(CH3)2.

6. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The nitrogen-containing organic ligand in the nitrogen-containing MOF material is selected from at least one of imidazole ligands, porphyrin ligands, and pyridine ligands; Preferably, the nitrogen-containing MOF material is selected from at least one of ZIF-8, ZIF-67, copper-based PCN-222, zirconium-based PCN-222, iron-based PCN-250, manganese-based PCN-222, indium-based USTC-8, and Mn-AdDB.

7. The method for preparing a low dielectric silicon nitride film according to claim 1, characterized in that: The plasma source gas is selected from at least one of nitrogen and argon plasma, nitrogen and helium plasma, ammonia plasma, nitrogen and ammonia plasma, ammonia and helium plasma, ammonia and argon plasma and NF3-containing plasma.

8. The method for preparing a low dielectric silicon nitride film according to any one of claims 1 to 7, characterized in that: The preparation method comprises repeating steps S1 to S3 at least once in sequence.

9. A low dielectric silicon nitride film prepared by the method according to any one of claims 1 to 8.

10. The low dielectric silicon nitride film according to claim 9, characterized in that: The metal content in the low dielectric silicon nitride film is 5 to 10 wt %; Preferably, the carbon content in the low dielectric silicon nitride film is 23-31 wt %.

11. Application of the low dielectric silicon nitride film according to claim 9 in the semiconductor industry.

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