KR20230131086A - Thin film improving composition, method for forming thin film using the same, semiconductor substrate and semiconductor device prepared therefrom - Google Patents

Abstract

The present invention relates to a thin film modified composition, a method of forming a thin film using the same, and a semiconductor substrate and semiconductor device manufactured therefrom, using a thin film modified composition composed of a film growth/film quality improvement compound of a predetermined structure and a solvent with a specified dielectric constant. By appropriately lowering the growth rate of the deposition film during a vacuum-based thin film process, even when forming a thin film on a substrate with a complex structure, step coverage and thickness uniformity of the thin film can be greatly improved, and the efficiency of the etch film can be improved. This has the effect of significantly reducing impurity contamination.

Description

Thin film modified composition, method of forming a thin film using the same, semiconductor substrate and semiconductor device manufactured therefrom

The present invention relates to a thin film modification composition, a method of forming a thin film using the same, and a semiconductor substrate and semiconductor device manufactured therefrom. More specifically, the present invention relates to a thin film modification composition consisting of a film growth/film quality improvement compound of a predetermined structure and a solvent with a specified dielectric constant. By using the composition to appropriately lower the growth rate of the deposition film during vacuum-based thin film processing, step coverage and thickness uniformity of the thin film can be greatly improved even when forming a thin film on a substrate with a complex structure, and the etch film It relates to a thin film modified composition that can improve efficiency and significantly reduces impurity contamination, a thin film formation method using the same, and a semiconductor substrate manufactured therefrom.

Due to improved integration of memory and non-memory semiconductor devices, the microstructure of substrates is becoming more complex day by day.

For example, the width and depth of microstructure (hereinafter also referred to as 'aspect ratio') is increasing to over 20:1 and over 100:1, and as the aspect ratio increases, it is possible to form a sediment layer with a uniform thickness along the complex microstructure plane. There is a problem that becomes difficult.

As a result, the step coverage, which defines the thickness ratio of the sedimentary layer formed at the top and bottom in the depth direction of the microstructure, remains at the 90% level, making it increasingly difficult to express the electrical characteristics of the device, and its importance is increasing. It is increasing. Since the step coverage of 100% means that the thickness of the sediment layer formed on the top and bottom of the microstructure is the same, there is a need to develop technology so that the step coverage is as close to 100% as possible.

The semiconductor thin film is made of a nitride film, a thin film, a metal film, etc. The nitride film includes silicon nitride (SiN), titanium nitride (TiN), and tantalum nitride (TaN), and the thin film includes silicon oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), and zirconium oxide (ZrO ₂ ). The metal film includes molybdenum film (Mo), tungsten (W), etc.

The thin film is generally used as a diffusion barrier between the silicon layer of a doped semiconductor and aluminum (Al), copper (Cu), etc. used as interlayer wiring materials. However, when depositing a tungsten (W) thin film on a substrate, it is used as an adhesion layer.

As seen earlier, in order to obtain excellent and uniform physical properties of the thin film deposited on the substrate, high step coverage of the thin film is essential. Therefore, ALD (atomic) process that utilizes surface reaction rather than CVD (chemical vapor deposition) process that mainly utilizes gaseous reaction. layer deposition) process is used, but there are still problems in realizing 100% step coverage.

When the deposition temperature is raised for the purpose of achieving 100% step coverage, step coverage becomes difficult. First, in a deposition process consisting of two precursors and reactants, an increase in deposition temperature leads to a steep increase in thin film growth rate (GPC). Not only does it cause this, but even if the ALD process is performed at 300 ℃ to alleviate the increase in GPC due to the increase in deposition temperature, the deposition temperature increases during the process, so it is difficult to say that it is a solution.

In addition, high-temperature processes are required to produce metal thin films with excellent film quality in semiconductor devices. Research results have been reported showing that the concentration of carbon and hydrogen remaining in the thin film decreases by increasing the atomic layer deposition temperature to 400°C (see paper J. Vac. Sci. Technol. A, 35 (2017) 01B130).

However, the higher the deposition temperature, the more difficult it is to secure the step coverage. First, in a deposition process consisting of two precursors and reactants, an increase in deposition temperature can result in a steep increase in GPC (thin film growth rate). In addition, it has been confirmed that GPC increases by about 10% at 300°C even when a known shielding agent is applied to alleviate the increase in GPC due to an increase in deposition temperature. In other words, when deposited above 360°C, it becomes difficult to expect the GPC reduction effect provided by conventionally known shielding agents.

Therefore, it is possible to effectively form a thin film with a complex structure even at high temperatures, and the residual amount of impurities is low, and a method of forming a thin film that significantly improves film quality such as step coverage, thickness uniformity and electrical characteristics of the thin film, and manufacturing from this method. There is a need for development of semiconductor substrates, etc.

In order to solve the problems of the prior art as described above, the present invention provides a thin film modification composition composed of a film growth/film quality improvement compound of a predetermined structure and a solvent with a specified dielectric constant to appropriately lower the growth rate of the deposited film during a vacuum-based thin film process. Even when forming a thin film on a substrate with a complex structure, step coverage and thickness uniformity of the thin film can be greatly improved, the efficiency of the etch film can be improved, and impurity contamination can be significantly reduced. The purpose is to provide a modified composition, a method of forming a thin film using the same, a semiconductor substrate manufactured therefrom, and a semiconductor device including the same.

The purpose of the present invention is to improve the density and dielectric properties of thin films by improving the crystallinity and oxidation fraction of thin films.

The above and other objects of the present invention can all be achieved by the present invention described below.

In order to achieve the above object, the present invention provides a liquid halogen compound having a vapor pressure of 1 torr (25°C) or more; and a non-polar solvent having a dielectric constant of 25 or less.

The thin film may be a vacuum-based deposition film or a vacuum-based etching film.

The liquid halogen compound may be an alkyl halide having 1 to 10 carbon atoms.

The liquid halogen compound may have a refractive index of 1.40 to 1.60, 1.40 to 1.58, or 1.40 to 1.56.

The liquid halogen compound may include compounds represented by the following formulas 1-1 to 1-9 when the thin film is a deposited film.

[Formula 1-1 to 1-9]

, , , , , , , ,

The liquid halogen compound may include compounds represented by the following formulas 2-1 to 2-3 when the thin film is an etch film.

[Formula 2-1 to 2-3]

, ,

The liquid halogen compound can control the reaction surface of the above-described deposition film or etch film.

In the present invention, a non-polar solvent having a dielectric constant of 25 or less can be used in combination with the liquid halogen compound.

The dielectric constant is preferably 25 or less, specifically 15 or less, and preferably 10 or less. In this range, it is not reactive with the above-described liquid halogen compound and is provided by the liquid halogen compound without adversely affecting the process. You can maximize the desired effect.

The non-polar solvent having a dielectric constant of 25 or less may be, for example, a hydrocarbon-based solvent, a halogen-based solvent, a heterocyclic-containing solvent, or an alcohol-based solvent.

Specific examples of the non-polar solvent having a dielectric constant of 25 or less include octane, 1,2-dichloroethane, dimethylethyl amine, tetrahydrofuran, N,N dimethylformamide, isobutyl alcohol, and ethyl alcohol. There may be more than one species.

In addition, the present invention

Treating the surface of the substrate loaded in the chamber with the thin film modification composition of claim 1; and

It includes sequentially injecting a precursor compound and a reaction gas into the chamber and forming a vacuum-based deposition thin film on the substrate in a vacuum of 20 to 800 ° C. and less than 760 torr,

A method of forming a thin film is provided, wherein the reaction gas is an oxidizing agent or a reducing agent.

The chamber may be an ALD chamber, CVD chamber, PEALD chamber or PECVD chamber.

The thin film modified composition and precursor compound may be transferred into the chamber by VFC method, DLI method, or LDS method.

At this time, the heating temperature of the deposition transfer line (hereinafter referred to as 'injection line') may be in the range of 25 to 200 ° C. for the substrate.

The thin film may be an oxide film or a nitride film.

The reaction gas may include O2, O3, N2O, NO2, H2O, or O2 plasma.

The thin film is Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, Ta, W, Re , Os, Ir, La, Ce, and Nd may be a thin film in which one or more layers of one or more metals are selected from the group consisting of La, Ce, and Nd.

The thin film may be used as a diffusion barrier film, an etch stop film, an electrode film, a dielectric film, a gate insulating film, a block thin film, or a charge trap.

In addition, the present invention

Including the step of injecting an etch material into the chamber to form a vacuum-based etch film on the substrate,

The etching material is one or more selected from Cl2, CCl4, CF2Cl2, CF3Cl, CF4, CHF3, C2F6, SF6, BCl3, Br2, and CF3Br.

The chamber may be an ALD chamber, CVD chamber, PEALD chamber or PECVD chamber.

The thin film modified composition and precursor compound may be transferred into the chamber by VFC method, DLI method, or LDS method.

The etching material may be used in combination with Ar, H2, or O2.

The thin film forming method using the thin film modified composition includes,

i) forming a modified region on the surface of the substrate loaded in the chamber by vaporizing the above-described thin film modified composition; and

ii) comprising the step of first purging the inside of the chamber with a purge gas.

The thin film modifier composition may be supplied by applying it to a substrate loaded in a chamber at a temperature of 20 to 800°C.

The liquid halogen compound and the nonpolar solvent constituting the thin film modified composition may be injected into the chamber separately or in a premixed state.

The thin film forming method is,

i) forming a modified region on the surface of the substrate loaded in the chamber by vaporizing the above-described thin film modified composition;

ii) first purging the inside of the chamber with a purge gas;

iii) vaporizing the precursor compound and adsorbing it to a region outside the modified region;

iv) secondary purging the inside of the chamber with a purge gas;

v) supplying a reaction gas inside the chamber; and

vi) thirdly purging the inside of the chamber with a purge gas; providing a thin film forming method comprising a.

The thin film modifier composition may be supplied by applying it to a substrate loaded in a chamber at a temperature of 20 to 800°C.

The liquid halogen compound and the nonpolar solvent constituting the thin film modified composition may be injected into the chamber separately or in a premixed state.

The precursor compounds include Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, Ta, W, It is a molecule composed of one or more types selected from the group consisting of Re, Os, Ir, La, Ce, and Nd, and may be a precursor having a vapor pressure of more than 0.01 mTorr and less than 100 Torr at 25 ° C.

The thin film modified composition or precursor compound may be vaporized and injected, followed by plasma post-treatment.

The amount of purge gas introduced into the chamber in steps ii) and iv) may be 10 to 100,000 times the volume of the introduced thin film modified composition or precursor compound.

The reaction gas is an oxidizing agent or a reducing agent, and the reaction gas, thin film modified composition, and precursor compound may be transferred into the chamber by VFC method, DLI method, or LDS method.

The substrate loaded in the chamber is heated to 100 to 800° C., and the ratio of the thin film modifier composition and the precursor compound introduced into the chamber (mg/cycle) may be 1:1 to 1:20.

Additionally, the present invention provides a semiconductor substrate characterized by comprising a thin film manufactured by the above-described thin film forming method.

The thin film may have a multilayer structure of two or three layers or more.

Additionally, the present invention provides a semiconductor device including the above-described semiconductor substrate.

The semiconductor substrate includes low resistive metal gate interconnects, high aspect ratio 3D metal-insulator-metal capacitors, and DRAM trench capacitors. , 3D Gate-All-Around (GAA), or 3D NAND flash memory.

According to the present invention, a complex structure is formed by appropriately lowering the growth rate of the deposited film during a vacuum-based thin film process by using a thin film modification composition consisting of a film growth/film quality improvement compound of a predetermined structure and a solvent with a specified dielectric constant. Even when forming a thin film on a substrate with a thin film, step coverage and thickness uniformity of the thin film can be greatly improved, the efficiency of the etch film can be improved, and impurity contamination can be significantly reduced. It has the effect of providing a composition.

In addition, when forming a thin film, process by-products are more effectively reduced, preventing corrosion or deterioration, and improving the crystallinity of the thin film by modifying the film quality, thereby improving the electrical properties of the thin film.

In addition, when forming a thin film, process by-products are reduced, the reaction rate is reduced, and the thin film growth rate is appropriately lowered, so that step coverage and thin film density can be improved even when forming a thin film on a substrate with a complex structure. Furthermore, a thin film forming method using this and a thin film density can be improved. There is an effect of providing a semiconductor substrate manufactured from.

Figures 1 to 3 are graphs measuring 1H NMR to confirm the reactivity during synthesis and deposition of the thin film modified composition. Figure 1 shows a thin film obtained using 2-chloro-2-methyl butane alone (top), 2-chloro -shows a thin film (bottom) obtained using a 1:1 molar ratio blend of 2-methyl butane and octane; Figure 2 shows a thin film (top) obtained using iodocyclopentane alone; Figure 3 shows a thin film obtained using a 1:1 molar ratio blend of 2-dichloroethane (bottom), and Figure 3 shows a thin film obtained using 1-chloro-1-methyl cyclohexane alone (top), 1-chloro-1 Thin films obtained using a 1:1 molar ratio blend of -methyl cyclohexane and octane are shown (below), respectively.

Hereinafter, the thin film modified composition of the present invention, the method of forming a thin film using the same, and the semiconductor substrate manufactured therefrom will be described in detail.

In this description, unless otherwise specified, the term “thin film modification” refers to controlling the substrate surface to be used as a surface chemical reaction surface in the deposition process.

In this description, unless otherwise specified, the term “film growth/improvement of film quality” refers to not only reducing, preventing, or blocking the adsorption of precursor compounds for forming thin films on the substrate, but also reducing the adsorption of process by-products on the substrate. This means improving film growth by blocking or blocking it, or improving film quality such as electrical properties and thin film density.

In this description, the dielectric constant may use a value known in the art (calculated value at 20°C) ( https://macro.lsu.edu/howto/solvents/Dielectric%20Constant%20.htm reference).

The present inventors have developed a thin film modification composition for modifying the surface of a substrate and improving the deposition or etching process in a vacuum-based deposition or etching process by using a film growth/film quality improvement compound of a predetermined structure and a solvent with a specified dielectric constant to improve the deposition or etching process. Even when forming a thin film on a substrate with a complex structure by appropriately lowering the growth rate, step coverage and thickness uniformity of the thin film can be greatly improved, and the efficiency of the etch film can be improved, especially with a thin thickness. It was confirmed that deposition was possible and that O, Si, metal, and metal oxides remaining as process by-products were improved, as well as the amount of carbon remaining, which was difficult to reduce in the past. Based on this, the present invention was completed by focusing on research on membrane growth/membrane quality improvement compounds.

The target to which the thin film improvement composition of the present invention is applied may be a vacuum-based deposition film or a vacuum-based etching film.

The deposition film or etching film is, for example, Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, It can be provided as one or more precursors selected from the group consisting of Ta, W, Re, Os, Ir, La, Ce, and Nd, and can provide a modified region for an oxide film, a nitride film, a metal film, or a selective thin film thereof, , In this case, the effect desired to be achieved in the present invention can be sufficiently achieved.

As a specific example, the thin film may have a composition of a silicon oxide film or a silicon nitride film.

The thin film can be used in semiconductor devices not only as a commonly used diffusion barrier film, but also as an etch stop film, electrode film, dielectric film, gate insulating film, block thin film, or charge trap.

For example, the precursor compound used to form a thin film in the present invention may be a compound represented by the following formula (3).

[Formula 3]

(In Formula 3, M is Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, At least one selected from Ta, W, Re, Os, Ir, La, Ce and Nd, and L1, L2, L3 and L4 are -H, -X, -R, -OR, -NR2 or Cp (cyclopentadiene ), where -X is F, Cl, Br, or I, and -R is C1-C10 alkyl, C1-C10 alkene, or C1-C10 alkane, which may be linear or cyclic and L1, L2, L3, and L4 may be formed from 2 to 6 depending on the oxidation value of the central metal.)

For example, if the central metal is divalent, L1 and L2 may be attached to the central metal as ligands, and if the central metal is hexavalent, L1, L2, L3, L4, L5, and L6 may be attached to the central metal, and L1 to Ligands corresponding to L6 may be the same or different from each other.

The M may be a type corresponding to a trivalent metal, tetravalent metal, pentavalent metal, or hexavalent metal, and is preferably hafnium (Hf), zirconium (Zr), aluminum (Al), niobium (Nb), or tel. It is rurium (Ta), and in this case, it has the advantages of greatly reducing process by-products, excellent step coverage, improving thin film density , and having superior electrical, insulating, and dielectric properties of the thin film.

The L1, L2, L3 and L4 may be the same or different as -R, -X or Cp, where -R is C1-C10 alkyl, C1-C10 alkene, or C1-C10 alkane, linear or It may have a cyclic structure.

In addition, L1, L2, L3 and L4 may be the same or different as -NR2 or Cp, where -R is H, C1-C10 alkyl, C1-C10 alkene, C1-C10 alkane, iPr, or It could be tBu.

Additionally, in Formula 3, L1, L2, L3, and L4 may be the same as or different from -H or -X, where -X may be F, Cl, Br, or I.

Specifically, as an example of an aluminum precursor compound, Al(CH ₃ ) ₃ , AlCl ₄ , etc. may be used.

For example, the hafnium precursor compound is tris(dimethylamido)cyclopentadienyl hafnium of CpHf(NMe ₂ ) ₃ ) and (methyl-3-cyclopentadiene of Cp(CH ₂ ) ₃ NM ₃ Hf(NMe ₂ ) ₂ Nylpropylamino)bis(dimethylamino)hafnium, etc. can be used.

For example, silicon precursor compounds include hexachlorodisilane (HCDS), dichlorosilane (DCS), tris(dimethylamino)silane (3DMAS), Bis(diethylamino)silane (BDEAS), and octamethylcyclotetrasiloxane (OMCTS).

The thin film modified composition of the present invention can control the growth of a vacuum-based thin film or control the film quality by reducing the speed of adsorption of the precursor compound on the substrate by controlling the surface on which the precursor compound is adsorbed to the substrate in advance.

The thin film modified composition includes a liquid halogen compound having a vapor pressure of 1 torr (25°C) or more; and a non-polar solvent having a dielectric constant of 25 or less. In this case, side reactions are suppressed when forming a deposition film or an etching film, and the growth rate of the thin film is controlled to reduce process by-products in the thin film, thereby reducing corrosion or deterioration, The crystallinity of the thin film is improved, and even when forming a thin film on a substrate with a complex structure, step coverage and thickness uniformity of the thin film are greatly improved while minimizing impurity contamination.

As a specific example, the halogen compound may have a refractive index in the range of 1.40 to 1.60, 1.40 to 1.58, or 1.40 to 1.56, and in this case, the effect of reducing process by-products is large, the step coverage is excellent, the thin film density is improved, and the electrical properties of the thin film are improved. The characteristics may be superior.

The liquid halogen compound is preferably used in an atomic layer deposition (ALD) process, in which case it effectively protects the surface of the substrate without interfering with adsorption of the precursor compound or etching by the etchant and effectively removes process by-products. There is an advantage to removing it.

The liquid halogen compound is preferably a liquid at room temperature (22°C), has a density of 0.8 to 2.5 g/cm ³ or 0.8 to 1.5 g/cm ³ , and has a vapor pressure (20°C) of 0.1 to 300 mmHg or 1 to 300 mmHg. Within this range, a modified area can be effectively formed, and step coverage, thin film thickness uniformity, and film quality can be improved.

More preferably, the liquid halogen compound may have a density of 0.75 to 2.0 g/cm ³ or 0.8 to 1.3 g/cm ³ and a vapor pressure (20° C.) of 1 to 260 mmHg, and the modified area may be within this range. It forms effectively and has excellent effects in step coverage, thin film thickness uniformity, and film quality improvement.

The liquid halogen compound is preferably used in an atomic layer etching (ALE) process. In this case, since chemical etching is used, it is effective in realizing selective etching and isostatic etching characteristics of the etch film to be provided.

Since the liquid halogen compound contains an alkyl halide having 1 to 10 carbon atoms, it has a significant effect of reducing process by-products, has excellent step coverage, and can improve thin film density and have superior electrical properties of the thin film.

The halogen included in the alkyl halide may be fluorine, bromine, chlorine, or iodine, and at least one halogen may be included in the alkyl halide. In this case, the effect of reducing process by-products is large, step coverage is excellent, and thin film density is increased. There is an advantage in that the improvement effect and the electrical properties of the thin film are superior.

When the thin film is a deposited film, the liquid halogen compound may preferably be at least one selected from compounds represented by the following formulas 1-1 to 1-9, and in this case, when forming the deposited film, a relatively sparse thin film is formed. By suppressing side reactions and controlling the growth rate of the thin film, process by-products in the thin film are reduced, reducing corrosion and deterioration, improving the crystallinity of the thin film, and providing step coverage even when forming a thin film on a substrate with a complex structure. ) and can greatly improve the thickness uniformity of the thin film, as well as minimize contamination by impurities.

[Formula 1-1 to 1-9]

, , , , , , , ,

When the thin film is an etch film, the liquid halogen compound may preferably be a compound represented by the following formulas 2-1 to 2-3, and in this case, the etching process can be effectively performed while minimizing contamination with impurities. .

[Formula 2-1 to 2-3]

, ,

The above-mentioned liquid halogen compound can be used alone, but considering the harsh vacuum-based atmosphere, it is preferable to use it together with a specific organic solvent to efficiently carry out the process.

The organic solvent used at this time can improve the process without affecting the reaction mechanism under vacuum of the above-mentioned liquid halogen compound by using a type with a dielectric constant of 15 or less.

Non-polar solvents having a dielectric constant of 25 or less may include hydrocarbon-based solvents, halogen-based solvents (excluding the above-described liquid halogen compounds), heterocyclic-containing solvents, or alcohol-based solvents.

The hydrocarbon solvent may be a linear hydrocarbon compound having an alkyl group having 1 to 10 carbon atoms. For example, octane (d: 1.9 at 25°C) may be used.

The halogen-based solvent may be a linear hydrocarbon compound substituted with a terminal halogen, wherein at least one, preferably two or more, halogens are substituted, for example, 1,2-dichloroethane (d: 10.7 at 25°C) ), etc. can be used.

The heterocycle-containing solvent may contain nitrogen or oxygen.

Examples of the nitrogen-containing solvent include dimethylethylamine (d: 3.2 at 25°C).

Examples of the oxygen-containing solvent include tetrahydrofuran (d: 7.6 at 25°C).

Examples of the alcohol-based solvent include isobutyl alcohol (d: 16.68 at 25°C), ethyl alcohol (d: 24.55 at 25°C), and the like.

As a specific example, the vacuum-based thin film modified composition may include one or more compounds selected from the compounds represented by the above-mentioned formulas 1-1 to 1-9 and a non-polar solvent having a dielectric constant of 25 or less, In this case, the effect of controlling the growth rate of the deposited film is large, the effect of removing process by-products is also large, the effect of improving step coverage and film quality is excellent, and even when applied to a substrate with a complex structure, the uniformity of the thin film is secured and the step coverage is greatly improved. It is improved, and in particular, it can be deposited at a thin thickness, and it can provide the effect of improving O, Si, metal, and metal oxides remaining as process by-products, and even the amount of carbon remaining, which was difficult to reduce in the past, and improves film quality even when manufacturing an etch film. It can provide an effect.

The reaction gas may include O ₂ , NH ₃ , or H ₂ .

The thin film is Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, Ta, W, Re , Os, Ir, La, Ce, and Nd may be a thin film in which one or more layers of one or more metals are selected from the group consisting of La, Ce, and Nd.

The thin film modified composition can provide a modified region for a thin film.

The thin film modifying composition is characterized in that it does not remain in the thin film.

At this time, not remaining means that, unless otherwise specified, when analyzing the components by This refers to the case where an element exists in less than 0.1 atom%. More preferably, in the secondary-ion mass spectrometry (SIMS) measurement method or the Considering the increase/decrease rate of N, Si, and halogen impurities, it is desirable that the signal sensitivity increase/decrease rate of each element species does not exceed 5%.

For example, the thin film may contain 100 ppm or less of a halogen compound.

The thin film may be used as a diffusion barrier film, an etch stop film, an electrode film, a dielectric film, a gate insulating film, a block thin film, or a charge trap, but is not limited thereto.

The liquid halogen compound, organic solvent, and precursor compound may preferably be a compound with a purity of 99.9% or higher, a compound with a purity of 99.95% or higher, or a compound with a purity of 99.99% or higher. For reference, when a compound with a purity of less than 99% is used, impurities are present. It may remain in the thin film or cause side reactions with precursors or reactants, so it is recommended to use 99% or more of the material if possible.

The thin film forming method of the present invention includes the steps of treating the surface of a substrate loaded in a chamber with the above-described thin film modification composition; and sequentially injecting a precursor compound and a reaction gas into the chamber and forming a vacuum-based deposition thin film on the substrate at a temperature of 20 to 800° C. and a vacuum of less than 760 torr, wherein the reaction gas is an oxidizing agent or a reducing agent. In this case, by reducing the deposition rate of the thin film on the substrate and appropriately lowering the thin film growth rate, even when forming a thin film on a substrate with a complex structure, step coverage and thickness uniformity of the thin film are greatly improved while impurities are reduced. It has the effect of minimizing pollution.

In the step of treating with the thin film modified composition, the feeding time (sec) of the thin film modified composition to the substrate surface is preferably 0.01 to 10 seconds, more preferably 0.02 to 8 seconds, and even more preferably 0.04 to 6 seconds per cycle. More preferably, it is 0.05 to 5 seconds, and within this range, the thin film growth rate is low, step coverage is excellent, and economic efficiency is excellent, and impurity contamination is minimized.

In this substrate, the feeding time of the precursor compound is based on a flow rate of 0.1 to 500 mg/cycle based on a chamber volume of 15 to 20 L, and more specifically, a flow rate of 0.8 to 200 mg/cycle in a chamber volume of 18 L. It is based on cycle.

The thin film modification method of the present invention includes the steps of i) vaporizing the above-described thin film modification composition to form a modified region on the surface of the substrate loaded in the chamber; and ii) first purging the inside of the chamber with a purge gas.

In a preferred embodiment, the thin film modification method, and further the thin film forming method, includes the steps of i) vaporizing the thin film modification composition and treating it on the surface of a substrate loaded in a chamber; ii) first purging the inside of the chamber with a purge gas; iii) vaporizing the precursor compound and adsorbing it on the surface of the substrate loaded in the chamber; iv) secondary purging the inside of the chamber with a purge gas; v) supplying a reaction gas inside the chamber; and vi) thirdly purging the inside of the chamber with a purge gas.

At this time, steps i) to vi) can be performed as a unit cycle and the cycle can be repeated until a thin film of the desired thickness is obtained. In this way, the thin film modified composition of the present invention can be produced within one cycle. When added before the precursor compound and adsorbed to the substrate, the thin film growth rate can be appropriately lowered even when deposited at high temperature, and the resulting process by-products are effectively removed, thereby reducing the resistivity of the thin film and greatly improving step coverage.

In another preferred embodiment, the substrate may be manufactured by applying the thin film modified composition to a substrate loaded in a chamber at a temperature of 20 to 800 °C.

As a preferred example of the thin film forming method of the present invention, the surface of the substrate can be activated by adding the thin film modified composition of the present invention before the precursor compound within one cycle, and then the precursor compound can be added and adsorbed to the substrate, In this case, even if the thin film is deposited at a high temperature, by appropriately reducing the growth rate of the thin film, process by-products can be greatly reduced and step coverage can be greatly improved, the formation of the thin film can be increased, the resistivity of the thin film can be reduced, and the aspect ratio is large. Even when applied to semiconductor devices, the thickness uniformity of the thin film is greatly improved, which has the advantage of securing the reliability of the semiconductor device.

For example, in the case of depositing the thin film modified composition before or after deposition of the precursor compound, the thin film forming method may be performed by repeating the unit cycle 1 to 99,999 times as needed, preferably 10 to 10,000 unit cycles, More preferably, it can be repeated 50 to 5,000 times, and even more preferably 100 to 2,000 times, and within this range, the desired thickness of the thin film can be obtained and the effect to be achieved in the present invention can be sufficiently obtained.

The precursor compounds include Al, Si, Ti, V, Co, Ni, Cu, Zn, Ga, Ge, Se, Zr, Nb, Mo, Ru, Rh, In, Sn, Sb, Te, Hf, Ta, W, It consists of C, N, O, H, In the case of a precursor that is a molecule having one or more types of ligand and has a vapor pressure of 1 mTorr to 100 Torr at 25°C, the effect of forming a modified region by the above-described thin film modified composition can be maximized despite natural oxidation.

In the present invention, the chamber may be, for example, an ALD chamber, a CVD chamber, a PEALD chamber, or a PECVD chamber.

The thin film is a silicon oxide film, a silicon nitride film, a titanium oxide film, a titanium nitride film, a hafnium oxide film, a hafnium nitride film, a zirconium oxide film, a zirconium nitride film, a tungsten oxide film, a tungsten nitride film, an aluminum oxide film, and an aluminum nitride film. , it may be a niobium oxide film, a niobium nitride film, a tallurium oxide film, or a tallurium nitride film.

In the present invention, the liquid halogen compound or precursor compound may be vaporized and injected, followed by plasma post-treatment. In this case, process by-products can be reduced while improving the growth rate of the thin film.

When first adsorbing the thin film modified composition on a substrate and then adsorbing the precursor compound and then adsorbing the precursor compound, the amount of purge gas introduced into the chamber in the step of purging the non-adsorbed thin film modifying agent or the thin film modified composition is The amount is not particularly limited as long as it is sufficient to remove the non-adsorbed thin film modified composition, but for example, it may be 10 to 100,000 times, preferably 50 to 50,000 times, more preferably 100 to 10,000 times, within this range. By sufficiently removing the non-adsorbed thin film modified composition, the thin film can be formed evenly and deterioration of film quality can be prevented. Here, the input amounts of the purge gas and the thin film modified composition are each based on one cycle, and the volume of the thin film modified composition is the volume of the opportunity thin film modified composition or the volume of the vapor of the vaporized liquid halogen compound and the non-polar solvent, respectively. it means.

As a specific example, when the injection amount of the thin film modified composition is 200 sccm and the purge gas flow rate is 5000 sccm in the step of purging the non-adsorbed thin film modified composition, the injection amount of the purge gas is 25 times the injection amount of the thin film modified composition.

In addition, the amount of purge gas introduced into the chamber in the step of purging the unadsorbed precursor compound is not particularly limited as long as it is an amount sufficient to remove the unadsorbed precursor compound, but for example, the volume of the precursor compound introduced into the chamber It may be 10 to 10,000 times, preferably 50 to 50,000 times, more preferably 100 to 10,000 times, and within this range, unadsorbed precursor compounds are sufficiently removed to form a thin film evenly and prevent deterioration of the film quality. It can be prevented. Here, the input amounts of the purge gas and the precursor compound are each based on one cycle, and the volume of the precursor compound refers to the volume of the opportunity precursor compound vapor.

In addition, in the purging step performed immediately after the reaction gas supply step, the amount of purge gas introduced into the chamber may be, for example, 10 to 10,000 times the volume of the reaction gas introduced into the chamber, and preferably 50 to 50,000 times. It may be 100 to 10,000 times, and more preferably 100 to 10,000 times, and the desired effect can be sufficiently obtained within this range. Here, the input amounts of the purge gas and reaction gas are each based on one cycle.

The thin film modified composition and precursor compound may preferably be transferred into the chamber by a VFC method, a DLI method, or an LDS method, and more preferably, they are transported into the chamber by an LDS method.

The liquid halogen compound and the non-polar solvent constituting the thin film modified composition may be transported separately into the chamber or together in a mixed state.

The substrate loaded in the chamber may be heated to 100 to 650° C., for example, to 150 to 550° C., and the thin film modified composition or precursor compound may be injected onto the substrate in an unheated or heated state. Depending on the deposition efficiency, the heating conditions may be adjusted during the deposition process after injection without heating. For example, it can be injected onto the substrate at 100 to 650°C for 1 to 20 seconds.

The dosage ratio (mg/cycle) of the precursor compound and the thin film modified composition in the chamber may preferably be 1:1.5 to 1:20, more preferably 1:2 to 1:15, and even more preferably 1:2 to 1:20. It is 1:12, and more preferably 1:2.5 to 1:10, and within this range, the effect of improving step coverage and reducing process by-products is significant.

For example, when using the thin film modified composition and the precursor compound, the thin film forming method may have a deposition rate reduction rate of 20% or more, preferably 50% or more, expressed by Equation 1 below, and in this case, the method having the above-described structure By using a film growth/film quality improvement compound or a thin film modification composition, a relatively sparse thin film is formed, and at the same time, the growth rate of the formed thin film is greatly reduced, ensuring uniformity of the thin film even when applied to a complex structure substrate at high temperature, greatly improving step coverage. In particular, it can be deposited to a thin thickness, and can provide the effect of improving O, Si, metal, and metal oxides remaining as process by-products, and even the amount of carbon remaining, which was difficult to reduce in the past.

[Equation 1]

Deposition rate reduction rate = [{(DR _i )-(DR _f )}/(DR _i )]×100

(In the above equation, DR (Deposition rate, Å/cycle) is the speed at which the thin film is deposited. In the deposition of a thin film formed from a precursor and a reactant, DR _i (initial deposition rate) is the rate of thin film formed without adding a thin film modifying composition. This is the deposition rate. DR _f (final deposition rate) is the deposition rate of the thin film formed by adding the thin film modified composition during the above process. Here, the deposition rate (DR) is 3 to 30 nm thick using an ellipsometer equipment. The value is measured at room temperature and pressure for thin films, and the unit is Å/cycle.)

즉, 증착 속도를 의미하고, 상기 증착 속도는 일례로 Ellipsometery로 3 내지 30 nm 두께의 박막을 상온, 상압 조건에서 박막의 최종 두께를 측정한 후 총 사이클 회수로 나누어 평균 증착 속도로 구할 수 있다.In Equation 1 above, the thin film growth rate per cycle with and without the thin film modification composition is expressed as the thin film deposition thickness per cycle (

In other words, it means the deposition rate, and the deposition rate can be obtained as an average deposition rate by measuring the final thickness of a 3 to 30 nm thick thin film at room temperature and pressure using ellipsometry, for example, and then dividing it by the total number of cycles.

In Equation 1, “when the thin film modified composition is not used” refers to the case where the thin film is manufactured by adsorbing only the precursor compound on the substrate in the thin film deposition process, and a specific example is the thin film modified composition in the thin film forming method. This refers to a case where a thin film is formed by omitting the step of adsorption and the step of purging the non-adsorbed thin film modified composition.

기준 박막 내 잔류 할로겐 세기(c/s)가 바람직하게 100,000 이하, 보다 바람직하게 70,000 이하, 더욱 바람직하게 50,000 이하, 보다 더욱 바람직하게 10,000 이하일 수 있고, 바람직한 일 실시예로 5,000 이하, 보다 바람직하게는 1,000 내지 4,000, 보다 더 바람직하게는 1,000 내지 3,800일 수 있으며, 이러한 범위 내에서 부식 및 열화가 방지되는 효과가 우수하다.The thin film forming method has a thin film thickness of 100, measured based on SIMS.

The residual halogen intensity (c/s) in the reference thin film may be preferably 100,000 or less, more preferably 70,000 or less, even more preferably 50,000 or less, even more preferably 10,000 or less, and in a preferred embodiment, 5,000 or less, more preferably 5,000 or less. It may be 1,000 to 4,000, more preferably 1,000 to 3,800, and within this range, the effect of preventing corrosion and deterioration is excellent.

In the present substrate, purging is preferably 1,000 to 50,000 sccm (Standard Cubic Centimeter per Minute), more preferably 2,000 to 30,000 sccm, and even more preferably 2,500 to 15,000 sccm, and within this range, the thin film growth rate per cycle is appropriately controlled, and a single There is an advantage in terms of film quality as deposition is performed at or close to an atomic mono-layer.

The ALD (Atomic Layer Deposition) process is very advantageous in the manufacture of integrated circuits (ICs) that require a high aspect ratio, and in particular, it provides excellent step conformality and uniform coverage due to a self-limiting thin film growth mechanism. There are advantages such as uniformity and precise thickness control.

For example, the thin film formation method can be carried out at a deposition temperature in the range of 50 to 800 ℃, preferably at a deposition temperature in the range of 300 to 700 ℃, more preferably at a deposition temperature in the range of 400 to 650 ℃. , More preferably, it is carried out at a deposition temperature in the range of 400 to 600 ℃, and even more preferably, it is carried out at a deposition temperature in the range of 450 to 600 ℃. Within this range, a thin film of excellent film quality while realizing ALD process characteristics is achieved. It has the effect of growing.

For example, the thin film formation method may be carried out at a deposition pressure in the range of 0.01 to 20 Torr, preferably in the range of 0.1 to 20 Torr, more preferably in the range of 0.1 to 10 Torr, and most preferably Typically, it is carried out at a deposition pressure in the range of 0.3 to 7 Torr, which is effective in obtaining a thin film of uniform thickness within this range.

In the present disclosure, the deposition temperature and deposition pressure may be measured as the temperature and pressure formed within the deposition chamber, or may be measured as the temperature and pressure applied to the substrate within the deposition chamber.

The thin film forming method preferably includes raising the temperature within the chamber to the deposition temperature before introducing the precursor compound into the chamber; And/or it may include the step of purging by injecting an inert gas into the chamber before introducing the precursor compound into the chamber.

In addition, the present invention is a thin film manufacturing device capable of implementing the thin film manufacturing method, including an ALD chamber, a first vaporizer for vaporizing the precursor compound, a first transport means for transporting the vaporized precursor compound into the ALD chamber, and a first vaporizer for vaporizing the thin film precursor. 2 It may include a thin film manufacturing apparatus including a vaporizer and a second transport means for transporting the vaporized thin film precursor into the ALD chamber. Here, the vaporizer and transport means are not particularly limited as long as they are vaporizers and transport means commonly used in the technical field to which the present invention pertains.

The heating temperature of the deposition transfer means (hereinafter referred to as 'injection line') may be in the range of 25 to 200 ° C for the substrate, and the reaction gas is O2, O3, N2O, NO2, H2O, or O2 plasma. may include.

According to another aspect of the present invention, treating the surface of a substrate loaded in a chamber with the above-described thin film modification composition; and injecting an etching material into the chamber to form a vacuum-based etching film on the substrate, wherein the etching material is selected from Cl2, CCl4, CF2Cl2, CF3Cl, CF4, CHF3, C2F6, SF6, BCl3, Br2, and CF3Br. A thin film forming method characterized by one or more types can be provided.

The etching material may be used by mixing with Ar, H2, or O2, and other than this, details that overlap with the deposition film formation will be omitted.

The present invention also provides a semiconductor substrate, which is characterized in that the semiconductor substrate is manufactured by the thin film forming method of the present substrate. In this case, the step coverage and thickness uniformity of the thin film are greatly excellent, and the thin film There are families with excellent density and electrical properties.

The thin film (thin film) may have a thickness of, for example, 0.1 to 20 nm, preferably 0.5 to 20 nm, more preferably 1.5 to 15 nm, and even more preferably 2 to 10 nm, and the thin film characteristics within this range. This has excellent effects.

The thin film may have a carbon impurity content of preferably 5,000 counts/sec or less or 1 to 3,000 counts/sec, more preferably 10 to 1,000 counts/sec, and even more preferably 50 to 500 counts/sec. Although the thin film characteristics are excellent within this range, the thin film growth rate is reduced.

For example, the thin film has a step coverage of 90% or more, preferably 92% or more, and more preferably 95% or more. Within this range, even a thin film with a complex structure can be easily deposited on a substrate, making it suitable for next-generation semiconductor devices. There are applicable benefits.

The manufactured thin film preferably has a thickness of 20 nm or less, a dielectric constant of 5 to 29 based on a thin film thickness of 10 nm, a carbon, nitrogen, and halogen content of 5,000 counts/sec or less, and a step coverage ratio of 90. % or more, and within this range, excellent performance as a dielectric film or blocking film is achieved, but it is not limited to this.

For example, the thin film may have a multi-layer structure of 2 or 3 layers or more, preferably 2 or 3 layers, as needed. The multilayer film having the two-layer structure may have a lower layer-middle layer structure as a specific example, and the multilayer film having the three-layer structure may have a lower layer film-middle layer-upper layer structure as a specific example.

The lower layer film is, for example, Si, SiO ₂ , MgO, Al ₂ O ₃ , CaO, ZrSiO ₄ , ZrO ₂ , HfSiO ₄ , Y ₂ O ₃ , HfO ₂ , LaLuO ₂ , Si ₃ N ₄ , SrO, La ₂ O ₃ , Ta ₂ O ₅ , BaO, TiO ₂ It may include one or more selected from the group consisting of.

For example, the multilayer film may include Ti _x N _y , preferably TN.

For example, the upper layer may include one or more selected from the group consisting of W and Mo.

The semiconductor substrate includes low resistive metal gate interconnects, high aspect ratio 3D metal-insulator-metal capacitors, and DRAM trench capacitors. , 3D Gate-All-Around (GAA), or 3D NAND flash memory.

Hereinafter, preferred embodiments and drawings are presented to aid understanding of the present invention. However, the following examples and drawings are merely illustrative of the present invention, and various changes and modifications are possible within the scope and technical spirit of the present invention. It is obvious that such changes and modifications fall within the scope of the appended patent claims.

[Example]

<Test Example 1>

Examples 1 to 4, Comparative Example 1, Reference Examples 1 to 2

For the experiment, among solvents with a dielectric constant value of 15 or less, a compound represented by the following formula 4-1 (d: 1.9 at 25℃), a compound represented by the following formula 4-2 (d: 3.2 at 25℃), and the following formula 4 A compound represented by -3 (d: 7.6 at 25°C), a compound represented by the following formula 4-4 (d: 10.7 at 25°C), a compound represented by the following formula 4-5 (d: 16.7 at 25°C) , a compound represented by the following formula 4-6 (d: 24.6 at 25°C), a compound represented by the following formula 4-7 (d: 36.7 at 25°C), and the above-mentioned formulas 1-1, 1-4, and 1. It was mixed with the compound represented by -7 at a 1:1 mole ratio, and the degree of reactivity was confirmed through ¹ H-NMR to determine whether new impurity peaks were present.

[Formula 4-1]

[Formula 4-2]

[Formula 4-3]

[Formula 4-4]

[Formula 4-5]

[Formula 4-6]

[Formula 4-7]

[Formula 1-1]

[Formula 1-4]

[Formula 1-7]

The obtained results are summarized in Table 1 below and Figures 1 to 3 below. Here, if a new impurity peak was observed, it was considered reactive and was marked as O, and if a new impurity peak was not observed, it was marked as X, meaning it was not reactive.

Liquid halogenated compounds
non-polar solvent Formula 1-1 Formula 1-4 Formula 1-7 Formula 4-1 (Example 1) X X X Formula 4-2 (Example 2) X X X Formula 4-3 (Example 3) X X X Formula 4-4 (Example 4) X X X Formula 4-5 (Reference Example 1) O O X Formula 4-6 (Reference Example 2) O O X Formula 4-7 (Comparative Example 1) O O O

As shown in Table 1 and Figures 1 to 3 below, in the case of Examples 1 to 4 in which compounds represented by formulas 4-1, 4-2, 4-3, and 4-4 with a dielectric constant of 15 or less were mixed, the liquid It was observed to be non-reactive regardless of the type of halogen compound, so it is believed to be effective in improving the deposition process.

Meanwhile, in the case of Reference Example 1, in which a compound represented by Chemical Formula 4-5 with a dielectric constant slightly exceeding 15 was mixed, it was observed that iodocyclopentane was not reactive, so the deposition process was carried out depending on the type of liquid halogen compound. It is judged to be appropriate for improving.

Meanwhile, Reference Example 2, which combines a compound represented by Chemical Formula 4-6 with a dielectric constant slightly exceeding 15, was also observed to have no reactivity in the case of iodocyclopentane, so the deposition process was carried out depending on the type of liquid halogen compound. It is judged to be appropriate for improvement.

On the other hand, in the case of Comparative Example 1, which blended the compound represented by Chemical Formula 4-7 with a dielectric constant far exceeding 25, it was observed to have reactivity regardless of the type of liquid halogen compound, so it would not be suitable for improving the deposition process. It is judged.

<Test Example 2>

An ALD deposition process was performed using the components and process shown in Table 1 above.

Specifically, in Table 1 below, a hexachlorodisilane (HCDS) precursor was used for SiN deposition in Comparative Example 1-1, the canister heating temperature was 35°C, the N2 carrier flow rate was 40 sccm for 3 seconds, and the NH3 flow rate was 1000. Inject sccm for 30 seconds, N2 purge flow rate is 1000 sccm for 12 seconds, and repeat 100~150 cycles.

At this time, the canister heating temperature was maintained at 50°C and the N2 carrier flow rate was 100 sccm for 3 seconds. In addition, the process of injecting the substances represented by the above-mentioned formulas 1-1, 1-4, and 1-7 separately for 3 seconds is repeated for 100 to 150 cycles.

Specifically, the substances represented by the formulas 1-1, 1-4, and 1-7 are mixed in an organic solvent represented by the formulas 4-1 to 4-6, respectively, at a 1:1 mole ratio with the composition shown in Table 1. Therefore, the liquid delivery system (LDS) was utilized.

The thickness of the 10nm SiN thin film of the thin films obtained in Examples 1 to 4, Comparative Example 1, and Reference Examples 1 to 2 was analyzed through ellipsometry optical analysis.

In addition, the thin films obtained in Examples 1 to 4, Comparative Examples 1, and Reference Examples 1 to 2 were obtained by measuring the thickness of a SiN thin film formed to a thickness of 10 nm through an ellipsometry optical analysis fitting and dividing the obtained thickness by the total ALD cycle. The thickness deposition rate per cycle (Å/cycle) was measured.

As a result, it was confirmed that the deposition rate was reduced by more than 20% in Examples 1 to 4 compared to Comparative Example 1. On the other hand, in the case of Reference Examples 1 and 2, it was confirmed that the deposition rate was reduced by more than 20% only when the compound represented by Chemical Formula 1-7 was used.

Claims (14)

Liquid halogen compounds having a vapor pressure of 1 torr (25°C) or more; and
A thin film modified composition comprising a non-polar solvent having a dielectric constant of 25 or less. According to paragraph 1,
A thin film modified composition, wherein the liquid halogen compound is an alkyl halide having 1 to 10 carbon atoms. According to paragraph 1,
A thin film modified composition, wherein the liquid halogen compound has a refractive index of 1.40 to 1.60. According to paragraph 1,
The liquid halogen compound includes compounds represented by the following formulas 1-1 to 1-9 when the thin film is a deposited film, and includes compounds represented by the following formulas 2-1 to 2-3 when the thin film is an etched film. A thin film modified composition characterized in that.
[Formula 1-1 to 1-9]
, , , , , , , ,
[Formula 2-1 to 2-3]
, , According to paragraph 1,
A vacuum-based thin film modified composition, wherein the non-polar solvent having a dielectric constant of 25 or less is a hydrocarbon-based solvent, a halogen-based solvent, a heterocycle-containing solvent, or an alcohol-based solvent. According to clause 5,
The nonpolar solvent having a dielectric constant of 25 or less is one or more selected from octane, 1,2-dichloroethane, dimethylethyl amine, tetrahydrofuran, N,N dimethylformamide, isobutyl alcohol, and ethyl alcohol. Characterized by a vacuum-based thin film modified composition. Treating the surface of the substrate loaded in the chamber with the thin film modification composition of claim 1; and
It includes sequentially injecting a precursor compound and a reaction gas into the chamber and forming a vacuum-based deposition thin film on the substrate in a vacuum of 20 to 800 ° C. and less than 760 torr,
A method of forming a thin film, wherein the reaction gas is an oxidizing agent or a reducing agent. Treating the surface of the substrate loaded in the chamber with the thin film modification composition of claim 1; and
Including the step of injecting an etch material into the chamber to form a vacuum-based etch film on the substrate,
A method of forming a thin film, wherein the etching material is one or more selected from Cl2, CCl4, CF2Cl2, CF3Cl, CF4, CHF3, C2F6, SF6, BCl3, Br2, and CF3Br. According to clause 7 or 8,
A method of forming a thin film, characterized in that the chamber is an ALD chamber, a CVD chamber, a PEALD chamber, or a PECVD chamber. According to clause 9,
The thin film modification composition and the precursor compound are transferred into the chamber by VFC method, DLI method, or LDS method, and the heating temperature of the injection line is 25 to 200 ℃ of the substrate. According to clause 8,
A method of forming a thin film, characterized in that the etching material is used in mixture with Ar, H2, or O2. A semiconductor substrate comprising a thin film manufactured by the thin film forming method according to claim 7 or 8. According to clause 12,
A semiconductor substrate, characterized in that the thin film has a multi-layer structure of two or three layers or more. A semiconductor device comprising the semiconductor substrate of claim 12.