Precursor for forming low-k thin film and method for forming low-k silicon-containing thin film using same

Abstract

The present invention relates to: a precursor for forming a low-k thin film, the precursor being characterized by comprising a silicon-containing compound represented by chemical formula 1; and a method for forming a low-k silicon-containing thin film using same. The precursor comprises a silicon-containing compound having a chemical structure including a vinyl group, is a liquid at room temperature and highly reactive, thus having an excellent film growth rate, and can form a silicon-carbon bridge (ex. Si-CH2-Si) in a thin film or control the carbon content and improve the elastic modulus of the thin film, and thus can form a high-quality low-k silicon-containing thin film.

Description

Precursor for forming a low-k thin film and method for forming a low-k silicon-containing thin film using the precursor

[0001] The present invention relates to a precursor comprising a novel compound for forming a low-k thin film and a method for forming a low-k silicon-containing thin film using the precursor, and more particularly, to a precursor comprising a novel compound that is liquid at room temperature and highly reactive through a chemical structure in which a vinyl group is bonded, and a method for forming a low-k silicon-containing thin film using the precursor.

[0002] As semiconductor devices become smaller and more highly integrated, parasitic capacitance increases, which in turn causes response speed delay (RC delay). Research and development are being conducted to address this. This parasitic capacitance is mainly caused by the metal wirings becoming very close together, resulting in the arrangement of the metal wirings having the same structure as a capacitor. To reduce this, it is necessary to form the interlayer insulating film formed between the metal wirings with a low dielectric constant and low permittivity insulating material.

[0003] Insulating materials with such low dielectric constants can be applied to various fields, such as inter-metal dielectric (IMD) films for metal wiring, and spacers with low dielectric constants used on the sidewalls of bit lines.

[0004] The low dielectric constant insulating material having the above low dielectric constant can be formed by the spin-on dielectric (SOD) method and the chemical vapor deposition (CVD) method, and examples of these include a fluorinated silicon oxide film (Fluorinated Silicate Glass, hereinafter referred to as FSG film) and a SiOC film.

[0005] Conventionally, precursors used to form low-k thin films include octamethylcyclotetrasiloxane (OMCTS), diethoxymethylsilane (DEMS), and tetraethoxyorthosilicate (TEOS). These precursors are liquid, which is advantageous for vaporization during the deposition process, but their application is limited due to the difficulty in obtaining a sufficient elastic modulus in the formed thin film.

[0006] For example, Republic of Korea Patent Publication No. 10-2020-0027115 describes a process for using OMTS and OMCTS as silicon precursors to form a low-k thin film. When an insulating film is formed using the silicon precursor, a thin film having a dielectric constant of 3 to 9 can be formed. However, there are limitations in forming a high-quality low-k thin film due to the properties or reactivity of the silicon-containing compound constituting the precursor, and in particular, there is a problem in that it is difficult to form a thin film having a high elastic modulus.

[0007] The present invention has been devised in consideration of the above-mentioned prior arts, and its purpose is to provide a precursor for forming a low-k thin film, which comprises a silicon-containing compound having a chemical structure including a vinyl group, is liquid at room temperature, has high reactivity, and thus has an excellent film growth rate, thereby forming a high-quality low-k thin film.

[0008] In addition, the purpose is to provide a precursor for forming a low-k silicon-containing thin film that can improve the elastic modulus by forming a silicon-carbon bridge (e.g., Si-CH2-Si) within the thin film or controlling the carbon content ratio.

[0009] The precursor for forming a low dielectric thin film of the present invention to achieve the above purpose is characterized by including a silicon-containing compound represented by the following chemical formula 1.

[0010] [Chemical Formula 1]

[0011]

[0012] In the above chemical formula 1,

[0013] R1 to R4 are each independently a hydrogen atom or a straight-chain, branched, or cyclic alkyl group, alkenyl group, allyl group, alkoxy group, phenyl group, or vinyl group having 1 to 6 carbon atoms, and n is an integer from 1 to 4.

[0014] At this time, at least one of R1 to R3 in the above chemical formula 1 may be a vinyl group.

[0015] Additionally, in the above chemical formula 1, n may be 2.

[0016] Additionally, in the above chemical formula 1, R4 may be a methyl group (Me).

[0017] Additionally, in the above chemical formula 1, at least one of R1 to R3 may be a methyl group (Me).

[0018] Additionally, in the above chemical formula 1, two of R1 and R3 may be methyl groups, and the remaining one may be a vinyl group.

[0019] The method for forming a low-k silicon-containing thin film of the present invention can be performed including a process of forming a thin film on a substrate using the precursor for forming the low-k silicon-containing thin film.

[0020] At this time, the process of forming a thin film on the substrate may include a process of forming a precursor thin film by depositing a precursor for forming the thin film on the surface of the substrate, and a process of reacting the precursor thin film with a reactive gas.

[0021] In addition, as the reactive gas, one or more of nitrogen (N2), ammonia (NH3), hydrazine (N2H4), nitrous oxide (N2O), oxygen (O2), water vapor (H2O), ozone (O3), hydrogen peroxide (H2O2), silane, hydrogen (H2), and diborane (B2H6) may be used.

[0022] Additionally, the process of forming the precursor thin film may include a process of vaporizing the precursor for forming the low-k silicon-containing thin film and transporting it into the chamber.

[0023] Additionally, the deposition may be performed by any one of a Spin-On Dielectric (SOD) process, a Low Temperature Plasma (LTP) process, a Chemical Vapor Deposition (CVD) process, a Plasma Enhanced Chemical Vapor Deposition (PECVD) process, a High Density Plasma Chemical Vapor Deposition (HDPCVD) process, an Atomic Layer Deposition (ALD) process, or a Plasma Enhanced Atomic Layer Deposition (PEALD) process.

[0024] In addition, the process of forming a thin film on the substrate may include a step of supplying a precursor for forming a thin film containing low dielectric constant silicon to the substrate and applying plasma to form a thin film.

[0025] In addition, the thin film obtained by the thin film forming process of the present invention may have a carbon content of 5 to 50 at% as measured by X-ray photoelectron spectroscopy (XPS). In addition, the thin film may have a refractive index (RI) of 1.40 to 1.50. In addition, the thin film may have an elastic modulus of 7 to 20 GPa. In addition, the thin film may have a dielectric constant of 2.5 to 4.5.

[0026] The precursor according to the present invention comprises a silicon-containing compound having a chemical structure including a vinyl group, is liquid at room temperature, has high reactivity, and has an excellent film growth rate. In addition, the elastic modulus can be improved by forming a silicon-carbon bridge (e.g., Si-CH2-Si) within the thin film or controlling the carbon content ratio.

[0027] In addition, a high-quality low-k silicon-containing thin film can be formed by performing a thin film formation process using the above precursor.

[0028] Figure 1 is a silicon-containing compound according to Example 1. 1 This is the result of H-NMR analysis.

[0029] Figure 2 shows the TGA analysis results of a silicon-containing compound according to Example 1.

[0030] The present invention will be described in more detail below. Terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Rather, they should be interpreted in a way that is consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention.

[0031] The precursor for forming a low dielectric thin film according to the present invention is characterized by including a silicon-containing compound represented by the following chemical formula 1.

[0032] [Chemical Formula 1]

[0033]

[0034] In the above chemical formula 1, R1 to R4 are each independently a hydrogen atom, a straight-chain, branched, or cyclic alkyl group, alkenyl group, allyl group, alkoxy group, phenyl group, or vinyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 4.

[0035] The silicon-containing compound represented by the above chemical formula 1, unlike OMTCS and other silicon precursors used in the past, has a chemical structure containing a vinyl group. This allows the formation of silicon-carbon bridges (e.g., Si-CH2-Si, Si-CHR-Si, Si-CR2-Si, etc.) within the thin film or the control of the carbon content during the thin film formation process, thereby enabling the formation of a high-quality silicon-containing, low-k thin film with a high elastic modulus.

[0036] The silicon-containing compound represented by the above chemical formula 1 can form various chemical structures depending on the combination of functional groups.

[0037] For example, in the above chemical formula 1, at least one of R1 to R3 may be a vinyl group. In addition, in the above chemical formula 1, n may be 2. In addition, in the above chemical formula 1, R4 may be a methyl group (Me), and at least one of R1 to R3 may be a methyl group (Me). In addition, in the above chemical formula 1, two of R1 and R3 may be methyl groups, and the remaining one may be a vinyl group.

[0038] A thin film formed using a precursor including a silicon-containing compound represented by the chemical formula 1 can have a high elastic modulus, and thus can be applied to semiconductor devices requiring high-quality thin films, such as next-generation DRAM IMD.

[0039] In addition, the precursor of the present invention may additionally include a solvent. Any solvent that can dissolve the silicon-containing compound may be used, for example, C1-C 16Any one or a mixture of saturated or unsaturated hydrocarbons, ketones, esters, glyme, dimethoxyethane (DME), diethylether, tetrahydrofuran (THF), ethers, dialkoxyalkane, pyridine, acetonitrile, primary, secondary or tertiary amines may be used. In addition, the C1-C 16 Examples of saturated or unsaturated hydrocarbons include toluene and heptane.

[0040] In particular, it is preferable to include a solvent capable of dissolving the silicon-containing compound in a solid state at room temperature depending on the form of the functional group. That is, when the solvent is included, it is included in a solvent capable of dissolving the silicon-containing compound and in an amount, and it is preferable to include it in an amount of 1 to 99 wt% based on the total weight of the precursor for forming the low-k thin film.

[0041] Since the precursor, with or without the solvent, is vaporizable, it can be supplied into the chamber in the form of a precursor gas. Accordingly, depending on the type of silicon-containing compound, if it exists in a liquid state at room temperature and can be easily vaporized, the thin film formation process can be performed without a separate solvent.

[0042] Therefore, a low-k silicon-containing thin film can be formed, including a process of forming a thin film on a substrate using a precursor for forming a low-k silicon-containing thin film of the present invention, and for this purpose, a process of vaporizing the low-k silicon-containing thin film forming precursor and transporting it into a chamber in which a substrate is installed can be performed. Specifically, the process of forming a thin film on the substrate can include a process of forming a precursor thin film by depositing the thin film forming precursor on the surface of the substrate, and a process of reacting the precursor thin film with a reactive gas.

[0043] At this time, as the reactive gas, one or more reactive gases may be used from among nitrogen (N2), ammonia (NH3), hydrazine (N2H4), nitrous oxide (N2O), oxygen (O2), water vapor (H2O), ozone (O3), hydrogen peroxide (H2O2), silane, hydrogen (H2), and diborane (B2H6), and the deposition may be performed by any one of a spin-on dielectric (SOD) process, a low temperature plasma (LTP) process, a chemical vapor deposition (CVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, a high density plasma chemical vapor deposition (HDPCVD) process, an atomic layer deposition (ALD) process, or a plasma enhanced atomic layer deposition (PEALD) process. The deposition process can be performed.

[0044] For example, when the HDPCVD process is applied, it can be performed under high vacuum and high power compared to the atmospheric pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD), or plasma-enhanced chemical vapor deposition (PECVD) process, so it is possible to form a thin film that is structurally dense and has excellent mechanical properties.

[0045] To this end, the thin film is formed by including a step of transferring the precursor for forming the low dielectric constant thin film into the chamber through DLI (Direct Liquid Injection), and a step of applying plasma while a source gas different from the precursor transferred into the chamber is supplied to the substrate.

[0046] For example, by supplying a precursor gas for forming a low-k thin film, such as oxygen gas, or an inert gas such as argon (Ar) or helium (He), onto a substrate having a metal wiring pattern formed thereon and generating plasma therein, a low-k interlayer insulating film that fills the gap between the metal wiring patterns formed on the substrate can be formed. In addition, when it is desired to form a silicon fluoride insulating film, a fluorine source gas can also be supplied to form the thin film.

[0047] In addition, depending on the type of interlayer insulating film, a precursor for forming a low-k silicon-containing thin film can be supplied to a substrate and plasma can be applied to form a thin film. By supplying hydrogen gas, which is a carrier gas, together with a silicon source gas, a fluorine source gas, an oxygen gas, and a gas containing carbon on the substrate and generating plasma, a low-k insulating film that fills the gap between metal wiring patterns on the substrate can be formed.

[0048] As the above fluorine source, SiF4, which is commonly used, can be used, and as the carbon-containing gas, a hydrocarbon gas such as CH4, C2H4, C2H6, C2H2, C6H6, or an organosiloxane source gas such as methylethoxysilane (MTES), diethoxymethylsilane (DEMS), dimethoxymethylsilane (DMOMS), tetramethylcyclotetrasiloxane (TOMCATS), dimethyldimethoxysilane (DMDMOS), dimethyldeoxysilylcyclohexane (DMDOSH), or trimethylsilane can be used.

[0049] The process for forming the above thin film can be performed under chamber pressure conditions of 1 to 10 Torr. In addition, the source power for forming plasma within the chamber is appropriately 15 to 9,000 W, and the bias power is appropriately 0 to 5,000 W. In addition, the bias power may not be applied in some cases.

[0050] In the above-described thin film formation process, due to the structural characteristics of the silicon-containing compound used in the present invention, fine voids may be formed when the interlayer insulating film is formed. By forming these voids, the dielectric constant of the interlayer insulating film can be further reduced, and a lower dielectric constant can be achieved compared to existing interlayer insulating films.

[0051] In addition, the mechanical properties of the formed thin film are improved because the bonding strength between the silicon-containing compound and the thin film surface is improved.

[0052] Therefore, the thin film obtained by the thin film forming process of the present invention may exhibit various characteristics. For example, the thin film may have a carbon content of 5 to 50 at% as measured by X-ray photoelectron spectroscopy (XPS). In addition, the thin film may have a refractive index (RI) of 1.40 to 1.50. In addition, the thin film may have an elastic modulus of 7 to 20 GPa. In addition, the thin film may have a dielectric constant of 2.5 to 4.5.

[0053] In addition, the thin film obtained by the thin film forming process of the present invention may have a film density of 1.3 to 1.6 g / cm3 or 2.2 to 2.5 g / cm3, and an etching rate of 0.03 to 9 Å / min during etching.

[0054] In addition, by applying the above thin film formation process, it is possible to manufacture semiconductor devices such as DRAM IMD including a low-k thin film. In addition, the low-k thin film forms an FSG (Fluorinated Silicate Glass) film or an OSG (Organo Silicate Glass) film as an interlayer insulating film, thereby reducing parasitic capacitance between wirings of the semiconductor device, thereby forming a high-quality semiconductor device.

[0055] The effects of the present invention are explained through the following examples.

[0056] Example 1. Preparation of 3,3,5,6,8,8-hexamethyl-4,7-dioxa-3,8-disiladeca-1,9-diene

[0057] A solution of 34 ml (0.37 mol) of 2,3-butanediol and 114 ml (0.82 mol) of triethylamine diluted in 3 L of hexane was cooled to a low temperature (approximately 0°C), and a solution of 90 g (0.74 mol) of chlorodimethylvinylsilane diluted in 200 mL of hexane was slowly added, followed by stirring at room temperature for approximately 18 hours. The final reactant was filtered, and the solvent of the obtained filtrate was removed under reduced pressure to obtain a colorless liquid. The obtained liquid was purified under reduced pressure [33.5°C@0.5 torr] to obtain 75 g (yield: 78%) of 2,3-bis(dimethylvinylsiloxy)butane as a colorless liquid.

[0058] The NMR analysis results of the product are as shown in Figure 1, and the characteristic peaks are as follows.

[0059] 1H-NMR(C6D6): δ0.21 [s, 12H, -Si(CH1CH2)(CH3)2], 1.14-1.18 [m, 6H, -OCH(CH3)], 3.63-3.69 [m, 1.5H, meso -OCH(CH3)], 3.75-3.81 [m, 0.5H, dl -OCH(CH3)], 5.72-5.79 [m, 1.8H, -Si(CH1CH2)(CH3)2], 5.91-5.96 [m, 1.8H, -Si(CH1CH2)(CH3)2], 6.16-6.25 [m, 1.4H, -Si(CH1CH2)(CH3)2]

[0060] In addition, as a result of TGA analysis on the compound of Example 1, it was found that a weight loss was observed in the range of 100 to 200°C as shown in Fig. 2, which could have a beneficial effect on the deposition process.

[0061] Fair example

[0062] A SiCOH thin film was formed through the thin film formation process of the present invention. Specifically, a silicon-containing precursor, oxygen, and helium were simultaneously injected using a deposition device to form a carbon-containing silicon oxide thin film.

[0063] To ensure stable silicon precursor injection during the process, argon (Ar) gas was used as a carrier gas in a precursor storage container (Canister) to supply the precursor to the reactor, and oxygen was used as a reactant to deposit a carbon-containing silicon oxide thin film using plasma vapor deposition. At this time, the substrate temperature was heated to 300°C, and the plasma was supplied with 450 W RF power at a frequency of 13.56 MHz.

[0064] Thin films were deposited by varying process conditions such as plasma application conditions, reactive gas, and carrier flow rate, and the dielectric constant and carbon content of each deposited thin film were measured.

[0065] The refractive index (RI) of the deposited thin films was analyzed by ellipsometry in the range of 1.3–5.0 eV, and the refractive index at 1.96 eV is attached to Table 1. The elemental composition ratio in the thin films, including the carbon content, was measured by XPS, and the density was measured by XRR. The dielectric constant was measured by contacting the deposited thin films using a Hg-probe, and the measurement was performed at an ac frequency of 10 kHz. The elastic modulus was measured by Nanoindenter, and the measurement was performed at 20% of the thickness from the surface of the deposited thin films.

[0066] The deposition conditions and measurement results for each thin film are shown in Table 1 below.

[0067] Deposition ConditionsMeasured ValuesRF Power [W]He Flow Rate [sccm]O2 Flow Rate [sccm]Electrode Spacing [mm]RIDielectric ConstantElastic Modulus [GPa]Carbon Content [at.%]145030020301.4382.9012.921.0245030030301.4313.8115.39.8345030040301.4434.5017.66.844503000301.4872.629.246.5

[0068] From the results in Table 1, it was confirmed that a high-quality low-k thin film can be formed by using the precursor for forming a thin film of the present invention.

[0069] While the present invention has been described with reference to preferred embodiments as described above, it is not limited to the above-described embodiments, and various modifications and variations are possible by those skilled in the art without departing from the spirit of the invention. Such modifications and variations are deemed to fall within the scope of the present invention and the appended claims.

Claims

1. A precursor for forming a low dielectric thin film, characterized in that it comprises a silicon-containing compound represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, R1 to R4 are each independently a hydrogen atom or a straight-chain, branched, or cyclic alkyl group, alkenyl group, allyl group, alkoxy group, phenyl group, or vinyl group having 1 to 6 carbon atoms, and n is an integer from 1 to 4.

2. In claim 1, A precursor for forming a low dielectric thin film, characterized in that at least one of R1 to R3 in the above chemical formula 1 is a vinyl group.

3. In claim 1, A precursor for forming a low dielectric thin film, characterized in that n in the above chemical formula 1 is 2.

4. In claim 1, A precursor for forming a low dielectric thin film, characterized in that in the above chemical formula 1, R4 is a methyl group (Me).

5. In claim 1, A precursor for forming a low dielectric thin film, characterized in that at least one of R1 to R3 in the above chemical formula 1 is a methyl group (Me).

6. In claim 1, A precursor for forming a low dielectric thin film, characterized in that two of R1 and R3 in the above chemical formula 1 are methyl groups and the remaining one is a vinyl group.

7. A method for forming a low-k silicon-containing thin film, characterized by including a process for forming a thin film on a substrate using a precursor for forming a low-k silicon-containing thin film according to any one of claims 1 to 6.

8. In claim 7, The process of forming a thin film on the above substrate is: A process of forming a precursor thin film by depositing the precursor for forming the thin film on the surface of a substrate; A process of reacting the above precursor thin film with a reactive gas; A method for forming a low dielectric constant silicon-containing thin film, characterized by including:

9. In claim 8, A method for forming a low dielectric constant silicon-containing thin film, characterized in that the reactive gas is one or more of nitrogen (N2), ammonia (NH3), hydrazine (N2H4), nitrous oxide (N2O), oxygen (O2), water vapor (H2O), ozone (O3), hydrogen peroxide (H2O2), silane, hydrogen (H2), and diborane (B2H6).

10. In claim 7, A method for forming a low-k silicon-containing thin film, characterized in that the process for forming the precursor thin film includes a process of vaporizing the precursor for forming the low-k silicon-containing thin film and transporting it into a chamber.

11. In claim 8, A method for forming a low-k silicon-containing thin film, characterized in that the above deposition is performed by any one of a spin-on dielectric (SOD) process, a low-temperature plasma (LTP) process, a chemical vapor deposition (CVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, a high-density plasma chemical vapor deposition (HDPCVD) process, an atomic layer deposition (ALD) process, or a plasma enhanced atomic layer deposition (PEALD) process.

12. In claim 7, The process of forming a thin film on the above substrate is: A method for forming a low-k silicon-containing thin film, characterized by comprising a step of supplying a precursor for forming a low-k silicon-containing thin film to a substrate and applying plasma to form a thin film.

13. In claim 7, A method for forming a low-k silicon-containing thin film, wherein the thin film has a carbon content of 5 to 50 at% as measured by X-ray photoelectron spectroscopy (XPS).

14. In claim 7, A method for forming a low dielectric constant silicon-containing thin film, characterized in that the thin film has a refractive index (RI) of 1.40 to 1.

50.

15. In claim 7, A method for forming a low dielectric constant silicon-containing thin film, wherein the thin film has an elastic modulus of 7 to 20 GPa.

16. In claim 7, A method for forming a low dielectric constant silicon-containing thin film, characterized in that the thin film has a dielectric constant of 2.5 to 4.5.

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