Film formation method, film formation material, and novel compound

Abstract

For example, the present disclosure provides a technique capable of forming a film by ALD even at a temperature of 400 degrees C. or higher.SOLUTION: LHf {N (C2H5) 2} 3 (L is a cyclopentadienyl group or a substituted cyclopentadienyl group. A novel compound represented by the formula (I): SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for forming hafnium oxide films, for example, by ALD. [Background technology]

[0002] It is desirable for the film formed in trenches and pores to be the same thickness regardless of location. ALD (Atomic Layer Deposition) is said to be superior to CVD (Chemical Vapor Deposition) in terms of film formation in high aspect ratio structures (trenches and pores). ALD allows for the formation of thin films of uniform thickness. From this perspective, ALD film formation technology is attracting attention in the semiconductor field.

[0003] The amount of film growth per cycle in the ALD process is called GPC (Growth Per Cycle). It is known that when the cycle time is fixed and the growth temperature (temperature during film formation: substrate temperature) is changed, the GPC behaves as shown in Figure 1.

[0004] Even if the temperature is changed, there is a region (ALD window) in which the GPC does not change (see Figure 1). It is said that ideal ALD proceeds in this region (ALD window). It is easy to understand that a wider region (ALD window) is preferable.

[0005] At temperatures lower than the ALD window, there are cases where GPC increases with increasing temperature, and cases where GPC decreases. In cases where GPC increases, the source adsorption rate is slow during the source supply stage, and saturated adsorption is not achieved within the specified source supply time. In this case, extending the source supply time will achieve saturated adsorption and widen the ALD window. The decrease in GPC with increasing temperature is related to the physical adsorption of the source gas. Physical adsorption occurs most significantly around the boiling point of the gas. The boiling point of the ALD source gas and the reaction temperature are often in the same temperature range. The effect of physical adsorption cannot be ignored in some cases. In such cases, the effect of physical adsorption can be reduced by adjusting the purging time after source supply. This is because the region where GPC increases or decreases on the high-temperature side above the ALD window is also shown in Figure 1. There is room for improvement by adjusting the process time.

[0006] HfO2 thin films are formed by ALD. In the semiconductor field, high-k / metal gate structures were first adopted in the 45nm process in 2007. HfO2 was used as the high-k material. Since then, HfO2 thin films have been used as dielectric materials in CPUs and DRAMs.

[0007] Amine-based materials (for example, TEMAHf: tetraethylmethylaminohafnium) have been proposed as materials (ALD materials) for forming HfO2 films by ALD.

[0008] It is said that a higher temperature (temperature of the substrate on which deposition is performed) during ALD film formation is preferable, because a higher substrate temperature results in a higher dielectric constant and better crystallinity of the film.

[0009] From this perspective, there is a demand for Hf compounds that can be formed into films at high temperatures (higher than the film formation temperature when TEMAHf is used).

[0010] WO2007 / 066546 discloses LHf(NR 1 R2 )3 (L is a cyclopentadienyl group or a substituted cyclopentadienyl group. R 1 , R 2 is an alkyl group.) For example, CpHf(NMe2)3 (cyclopentadienyltris(dimethylamino)hafnium), CpHf(NMeEt)3 (cyclopentadienyltris(methylethylamino)hafnium), (MeCp)Hf(NMe2)3, and (EtCp)Hf(NMe2)3 are disclosed.

[0011] When forming a HfO2 film by ALD using the CpHf(NMe2)3, if the film formation temperature (substrate temperature) was high (e.g., 450°C), the uniformity of the film formed in the high aspect ratio structure was poor. The film thickness was not uniform. If the substrate temperature was low (e.g., 350°C), the crystallinity of the obtained film was poor. The deterioration of crystallinity leads to a decrease in the dielectric constant. In any case, the HfO2 film obtained by the ALD method using the above-mentioned CpHf(NMe2)3 was found to have quality problems. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] WO2007 / 066546 [Non-patent literature]

[0013] [Non-Patent Document 1] Chem. Mater. 2002, 14, 4350 Summary of the Invention [Problem to be solved by the invention]

[0014] In recent years, in order to accommodate the miniaturization and complexity of semiconductor device structures, the adoption of 3D structures, and high aspect ratios, there is a demand for materials that can be deposited by ALD at high temperatures.

[0015] The problem to be solved by the present invention is to provide a technology that enables film formation by ALD at temperatures higher than that of CpHf(NMe2)3, for example, at temperatures of 400°C or higher. [Means for solving the problem]

[0016] The present invention proposes a novel compound represented by the following formula [I]: Formula [I] LHf{N(C2H5)2}3 (L is a cyclopentadienyl group or a substituted cyclopentadienyl group.)

[0017] The present invention proposes a novel compound represented by the following formula [Ia]: Formula [Ia] CpHf{N(C2H5)2}3

[0018] The present invention provides A film formation material used in forming a hafnium-based film on a substrate by ALD, The material comprises a compound represented by formula [I] We propose film formation materials.

[0019] The present invention provides A film formation material used in forming a hafnium-based film on a substrate by ALD, The material comprises a compound represented by formula [Ia]. We propose film formation materials.

[0020] The present invention provides A film formation material used in forming a hafnium oxide-based film on a substrate by ALD, The material comprises a compound represented by formula [I] We propose film formation materials.

[0021] The present invention provides A film formation material used in forming a hafnium oxide-based film on a substrate by ALD, The material comprises a compound represented by formula [Ia]. We propose film formation materials.

[0022] The present invention provides 1. A method for depositing a hafnium oxide-based film on a substrate by ALD, comprising: The substrate placed in the film formation chamber is heated to 400°C or higher, The substance represented by the formula [I] is supplied to the film formation chamber. A film formation method is proposed.

[0023] The present invention provides 1. A method for depositing a hafnium oxide-based film on a substrate by ALD, comprising: The substrate placed in the film formation chamber is heated to 400°C or higher, The substance represented by the formula [Ia] is supplied to the film formation chamber. A film formation method is proposed.

[0024] The present invention proposes the film formation method, wherein the substrate placed in the film formation chamber is preferably heated to 450° C. or higher.

[0025] The present invention proposes the film formation method, wherein the substrate placed in the film formation chamber is preferably heated to 600° C. or less.

[0026] The present invention proposes the film formation method, wherein the substrate placed in the film formation chamber is preferably heated to 550° C. or less.

[0027] The present invention proposes a film formation method in which an oxidizing agent is supplied to the film formation chamber.

[0028] The present invention proposes the film formation method, wherein the deposition rate per cycle during film formation is preferably 0.1 nm / cycle or less.

[0029] The present invention proposes the film formation method, wherein the exposure dose of the substrate to the substance represented by formula [I] is preferably 0.1 torr·second or more.

[0030] The present invention proposes a film formation method as described above, wherein the exposure dose of the substrate to the substance represented by formula [I] is preferably 10 torr·seconds or more.

[0031] The present invention proposes the film formation method, wherein the exposure dose of the substrate to the substance represented by formula [Ia] is preferably 0.1 torr·second or more.

[0032] The present invention proposes the film formation method, wherein the exposure dose of the substrate to the substance represented by formula [Ia] is preferably 10 torr·seconds or more.

[0033] The present invention proposes a film formation method, wherein the substrate having the compound of formula [I] or formula [Ia] attached thereto is exposed to an oxidizing agent for an exposure amount of preferably 1 torr·second or more. [Effects of the Invention]

[0034] The compound represented by formula [I] [Ia] is a liquid at 25°C (1 atmosphere). Therefore, problems are unlikely to occur when transporting the compound to the film formation chamber. For example, there is no need to specially heat the transport path. When attempting to transport a solid, there is a risk that the solid substance will adhere to or deposit on the inner wall of the transport path, causing the transport path to become blocked. To avoid this, the transport path for transporting the substance to the film formation chamber needs to be heated. However, since the compound represented by formula [I] [Ia] is a liquid, such problems are unlikely to occur. The compound was transported stably to the film formation chamber.

[0035] When a film was formed using the compound represented by formula [I] [Ia], it was possible to form the film by ALD even when the substrate on which the film was to be deposited was heated to 400°C or higher. The compound represented by formula [I] [Ia] had a wide ALD window (the region in which ideal ALD proceeds). The Hf-based film obtained by ALD when the substrate was heated to 400°C or higher had a nearly uniform film thickness, good crystallinity, and high-K. Semiconductor devices equipped with such films exhibited high performance.

[0036] In contrast, when CpHf(NMe2)3 was used and the substrate was heated to approximately 400°C, the film was deposited by CVD, which did not correspond to ALD. As a result, film deposition in high aspect ratio structures (trenches and pores) was poor. The film thickness varied greatly depending on the location. [Brief explanation of the drawings]

[0037] [Figure 1] ALD-GPC temperature dependence graph [Figure 2] ALD Flowchart [Figure 3] Graph of deposition rate and exposure amount of hafnium source in examples [Figure 4] SEM photograph of Example 5 [Figure 5] SEM photograph of Example 6 [Figure 6] Graph of substrate temperature and deposition rate for Example and Comparative Example 1 [Figure 7] SEM photo of Comparative Example 1 [Figure 8] SEM photo of Comparative Example 2 [Figure 9] XRD diffraction pattern DETAILED DESCRIPTION OF THE INVENTION

[0038] The first invention relates to novel compounds represented by the following general formula [I] and / or [Ia].

[0039] Formula [I] LHf{N(C2H5)2}3 (L is a cyclopentadienyl group or a substituted cyclopentadienyl group.) The substituent is preferably an alkyl group, more preferably an alkyl group having a carbon number of 1 to 4. Examples include -CH3, -C2H5, -C3H7, and the like.

[0040] Formula [Ia] CpHf{N(C2H5)2}3 Among the compounds of formula [I], the compound of formula [Ia] was particularly preferred.

[0041] The compound was obtained according to the method disclosed in Japanese Patent No. 5128289 (WO2007 / 066546). The compound was a liquid (25°C (1 atmosphere)).

[0042] The second invention is a film-forming material used in forming a hafnium-based film (particularly preferably a hafnium oxide-based film, such as a hafnium oxide (HfOx (x is a number from 1 to 2)) film) on a substrate by ALD. The material (ALD material) comprises a compound represented by formula [I] or [Ia].

[0043] The third aspect of the present invention is a method for forming a hafnium oxide-based film (e.g., hafnium oxide (HfOx, where x is a number from 1 to 2)) on a substrate by ALD. The substrate placed in a film formation chamber is preferably heated to 400°C or higher. A more preferred heating temperature is 450°C or higher. A more preferred heating temperature is 600°C or lower. A more preferred heating temperature is 550°C or lower. A substance represented by formula [I] and / or [Ia] is supplied to the film formation chamber. When a compound represented by formula [I] or [Ia] is used to form a film by ALD, the film was formed by ALD even at a high film formation temperature. When a compound not represented by formula [I] or [Ia], such as Hf(NEt2)4 or CpHf(NMe2)3, is used, the film was formed by CVD rather than ALD. The GPC (deposition rate per cycle during film formation) is preferably 0.1 nm / cycle or less. If the GPC value was too large, the quality of the film was reduced. The exposure amount of the substrate to the substance represented by formula [I] and / or [Ia] was preferably 0.1 torr·sec or more, and more preferably 10 torr·sec or more. If the exposure amount was small, it was difficult to obtain a uniform film. The exposure amount of the substrate to which formula [I] or formula [Ia] was attached was preferably 1 torr·sec or more, and the quality of the hafnium oxide film tended to decrease.

[0044] The ALD films obtained in this way had uniform thickness even in areas with high aspect ratio structures (trenches and pores), high crystallinity, and high-K properties.

[0045] According to the above invention, the problem that the present invention was intended to solve was solved.

[0046] In the present invention, the ALD is not limited to ALD in the narrow sense, but also includes ALD in the broad sense and similar ALDs, such as Plasma Enhanced Atomic Layer Deposition (PEALD), thermal ALD, and ALD employing radiation (X-rays, electron beams, electromagnetic waves, or light).

[0047] FIG. 2 is a flowchart of the film formation method (method of forming an HfO2 film by ALD) according to the present invention.

[0048] First, a base (substrate) is held (placed) in a film formation apparatus (film formation chamber). After this, the substrate is heated to a predetermined temperature, for example, 370 to 550°C.

[0049] After this, Hf source gas (e.g., CpHf(C2H5)3) was introduced into the film formation chamber (first step). At this time, a solvent gas (e.g., hydrocarbon or organic solvent such as ether) dissolving the Hf source and a carrier gas (inert gas (e.g., N2, Ar, He, etc.)) were also introduced into the film formation chamber. (Partial pressure of the source gas × time) was preferably 0.1 torr·sec or more. If the partial pressure was less than 0.1 torr·sec, the film obtained by ALD had poor film thickness uniformity.

[0050] Next, the film formation chamber was evacuated to a vacuum. An inert gas (e.g., N2 gas) was supplied. This operation purged the unreacted source gas and by-products (step 2). It is easy to understand that if step 2 were omitted and the process proceeded directly from step 1 to step 3, the oxidation would not proceed smoothly.

[0051] After this, an oxidizing agent (e.g., a mixture of O2 and O3, O2 or O3 gas alone, oxygen plasma, or other oxidizing gases such as H2O2) was supplied into the deposition chamber. The substrate was exposed to the oxidizing agent (step 3). This oxidized the Hf, resulting in an oxide film. The exposure time (oxidizing gas partial pressure × time) was preferably 1 torr·sec or more. If the exposure time was less than 1 torr·sec, the quality of the oxide film obtained by ALD was poor.

[0052] The film formation chamber was again evacuated to a vacuum, and an inert gas (e.g., N2 gas) was supplied into the chamber. This operation purged the unreacted oxidizing agent and by-products (fourth step).

[0053] The series of steps from step 1 to step 4 constitutes one cycle of the ALD process. The series of steps is repeated n (1≦n) times (n cycle). However, it is easy to understand that in the final n cycle, step 4 after step 3 may be omitted. It is also easy to understand that step 4 is necessary in the cycle just before the final n cycle (k cycle (k≦(n-1))). As a result, a hafnium oxide film (e.g., HfO2 film) of the desired thickness is formed.

[0054] In the above process, there may be a step of exposing the substrate surface to a chemical that acts on the substrate surface to inhibit film formation, and a step of exposing the substrate surface to a chemical that assists in the discharge of by-products.

[0055] The present invention will be described in more detail below. The following description is merely a preferred exemplary embodiment. The present invention is not limited thereto. Various modifications are also included without departing from the spirit and scope of the present invention as defined in the claims.

[0056] [Example 1] CpHf(NEt) was obtained according to the method disclosed in Japanese Patent No. 5128289. The compound was a liquid (25°C, 1 atm).

[0057] The series of steps from the first to fourth steps (1 cycle) was repeated 80 times (80 cycles). The substrate was a silicon wafer. The substrate heating temperature was 450°C. The Hf source was CpHf(N(C2H5)2)3. The exposure dose of CpHf(N(C2H5)2)3 in the first step was 1.5 torr·sec. The oxidizing agent used in the third step was a mixed gas of O2 and O3 (O3 was 4 mol%). The exposure dose of the mixed gas to the substrate was 700 torr·sec. A HfO2 film was formed.

[0058] The thickness and refractive index of the obtained HfO2 film were measured using a spectroscopic ellipsometer {UVISEL / M200-VIS-FGMS (Horiba, Ltd.)}. The refractive index (wavelength = 633 nm) was 2.060. The following relationship exists between the refractive index n and the dielectric constant ε: n = (ε·μ) 1 / 2 [μ is magnetic permeability (μ≒1 for materials other than ferromagnetic materials)]. Therefore, the HfO2 film is high-K. The HfO2 film had high crystallinity. The film thickness of the HfO2 film was 2.56 nm, and the GPC was 0.032 nm / cycle. The HfO2 film had excellent film thickness uniformity.

[0059] The same procedure was followed, except that the CpHf(NEt2)3 exposure was changed from 1.5 torr·sec to 4 torr·sec. The thickness and refractive index of the resulting HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.030. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 5 nm, and the GPC was 0.0625 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0060] The same procedure was followed, except that the CpHf(NEt2)3 exposure was changed from 1.5 torr·sec to 10 torr·sec. The thickness and refractive index of the resulting HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.089. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 6.48 nm, and the GPC was 0.081 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0061] The same procedure was followed, except that the CpHf(NEt2)3 exposure was changed from 1.5 torr·sec to 20 torr·sec. The thickness and refractive index of the resulting HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.095. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 6.832 nm, and the GPC was 0.0854 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0062] FIG. 3 shows the relationship between the exposure amount of CpHf(NEt2)3 and the film formation rate. The deposition rate was stable when the CpHf(NEt2)3 exposure was 0.1 torr·sec or higher, confirming that the deposition was based on ALD.

[0063] When the obtained HfO2 film was measured by XPS, no C or N components were found in the film. The purity of the HfO2 film was high. The film had high crystallinity. It was a high-K material.

[0064] [Example 2] The procedure was the same as in Example 1, except that the substrate heating temperature was 550° C. and the exposure amount of CpHf(NEt 2 ) 3 in the first step was 10 torr·seconds.

[0065] The thickness and refractive index of the obtained HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.037. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 5.008 nm, and the GPC was 0.0626 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0066] The same procedure was followed, except that the CpHf(NEt2)3 exposure was changed from 10 torr·sec to 25 torr·sec. The thickness and refractive index of the resulting HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.037. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 5.688 nm, and the GPC was 0.0711 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0067] FIG. 3 shows the relationship between the exposure amount of CpHf(NEt2)3 and the film formation rate. The deposition rate was stable when the CpHf(NEt2)3 exposure was 10 torr·sec or more. It was confirmed that deposition was based on ALD when the exposure was 10 torr·sec or more.

[0068] When the obtained HfO2 film was measured by XPS, no C or N components were found in the film. The purity of the HfO2 film was high. It was a high-K material.

[0069] [Example 3] The procedure was the same as in Example 1, except that the substrate heating temperature was 500° C. and the exposure amount of CpHf(NEt 2 ) 3 in the first step was 10 torr·seconds.

[0070] The thickness and refractive index of the obtained HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.060. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 5.559 nm, and the GPC was 0.0695 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0071] When the HfO2 film was measured by XPS, no C or N components were found in the film. The purity of the HfO2 film was high. It was a high-K material.

[0072] [Example 4] The procedure was the same as in Example 1, except that the substrate heating temperature was 400° C. and the exposure amount of CpHf(NEt 2 ) 3 in the first step was 10 torr·seconds.

[0073] The thickness and refractive index of the obtained HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.008. Therefore, the HfO2 film is a high-K film. The crystallinity of the HfO2 film was high. The thickness of the HfO2 film was 6.601 nm, and the GPC was 0.083 nm / cycle. The HfO2 film had excellent thickness uniformity.

[0074] When the obtained HfO2 film was measured by XPS, no C or N components were found in the film. The purity of the HfO2 film was high. It was a high-K material.

[0075] [Example 5] The procedure was the same as in Example 1, except that the number of cycles was changed from 80 to 100, and the substrate was changed to a silicon wafer with a predetermined pattern.

[0076] The cross section of the deposited HfO2 film was observed with a scanning electron microscope (SEM). The HfO2 film had excellent thickness uniformity. There was no significant difference in thickness between the film deposited in the lower and upper parts of the pores (high aspect ratio structure) (see Figure 4).

[0077] [Example 6] The procedure was the same as in Example 2, except that the number of cycles was changed from 80 to 200, and the substrate was changed to a silicon wafer with a predetermined pattern. The cross section of the deposited HfO2 film was observed by SEM. The HfO2 film had excellent thickness uniformity. There was no significant difference in thickness between the film deposited in the lower and upper parts of the pores (high aspect ratio structure) (see Figure 5).

[0078] [Example 7] The procedure was the same as in Example 1, except that the substrate heating temperature was 300° C. and the exposure amount of CpHf(NEt 2 ) 3 in the first step was 10 torr·seconds. The thickness and refractive index of the obtained HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.076. The thickness of the HfO2 film was 10.406 nm, and the GPC was 0.13 nm / cycle. When the HfO2 film was measured using XPS, no C or N components were detected in the film. The purity of the HfO2 film was high. However, the crystallinity of the HfO2 film was inferior to that of the film in Example 1. The inventors believe that this problem in crystallinity was due to the large GPC (>0.1 nm / cycle).

[0079] [Example 8] The procedure was the same as in Example 7, except that the substrate heating temperature was changed to 350°C. The thickness and refractive index of the obtained HfO2 film were measured using a UVISEL / M200-VIS-FGMS. The refractive index (wavelength = 633 nm) was 2.087. The thickness of the HfO2 film was 8.675 nm, and the GPC was 0.108 nm / cycle. When the HfO2 film was measured using XPS, no C or N components were detected in the film. The purity of the HfO2 film was high. However, the crystallinity of the HfO2 film was inferior to that of the film in Example 1. The inventors believe that this problem in crystallinity was due to the large GPC (>0.1 nm / cycle).

[0080] The relationship between the deposition rate of the HfO2 film obtained in the above example (Hf source exposure dose: approximately 10 torr / sec) and the substrate heating temperature is shown in Figure 6. When the compound represented by formula [I] or [Ia] was used to deposit the film by ALD, the deposition rate was stable over a wide temperature range (300°C to 550°C). There is an ALD window over a wide temperature range.

[0081] [Comparative Example 1] The procedure was the same as in Example 1, except that Hf(NEt2)4 was used instead of CpHf(NEt2)3, the Hf(NEt2)4 exposure dose was 0.4 torr·sec, and the substrate heating temperature was maintained between 250°C and 500°C. The thickness of the obtained HfO2 film was measured using a UVISEL / M200-VIS-FGMS. When the substrate heating temperature was 250°C, the GPC was 0.136 nm / cycle. When the substrate heating temperature was 350°C, the GPC was 0.150 nm / cycle. When the substrate heating temperature was 400°C, the GPC was 0.174 nm / cycle. When the substrate heating temperature was 450°C, the GPC was 0.186 nm / cycle. When the substrate heating temperature was 500°C, the GPC was 0.221 nm / cycle. The GPC increased with increasing temperature. This suggests that ideal ALD was not being performed. Incidentally, based on the knowledge obtained in the above example (the higher the substrate heating temperature, the better the crystallinity of the obtained film), when the HfO2 film obtained at a substrate heating temperature of 450°C was observed with a SEM (scanning electron microscope), a large difference in film thickness was found between the film formed at the lower part of the hole and the film formed at the upper part at the hole location (high aspect ratio structure) (see Figure 7). A uniform HfO2 film was not obtained.

[0082] Comparative Example 2 The procedure was the same as in Example 1, except that CpHf(NMe2)3 was used instead of CpHf(NEt2)3, the CpHf(NMe2)3 exposure dose was 0.4 torr·sec, and the substrate heating temperature was maintained at 450 °C. When the obtained HfO2 film was observed with a SEM (scanning electron microscope), a large difference in film thickness was observed between the film formed on the lower part of the hole and the film formed on the upper part at the pore location (high aspect ratio structure) (see Figure 8). A uniform HfO2 film was not obtained.

[0083] Figure 9 shows the XRD diffraction pattern, which shows that a crystalline film is formed at a film formation temperature of 400°C or higher.

Claims

1. 1. A method for depositing a hafnium oxide-based film on a substrate by ALD, comprising: the substrate placed in the film formation chamber is heated to 400°C or higher; A substance represented by the following formula [I] is supplied to the film formation chamber: Film formation method. Formula [I] LHf{N(C ２ H ５ ) ２ } ３ (L is a cyclopentadienyl group or a substituted cyclopentadienyl group.)

2. The substance represented by the formula [I] is CpHf{N(C ２ H ５ ) ２ } ３ is The film forming method according to claim 1.

3. The substrate is exposed to the substance represented by formula [I] for an exposure amount of 10 torr·seconds or more. The film forming method according to claim 1.

4. The film formation chamber ２ and / or O ３ is supplied The film forming method according to claim 1.

5. The heating temperature of the substrate is 450° C. or higher. The film forming method according to claim 1.

6. The heating temperature of the substrate is 600° C. or less. The film forming method according to claim 1 or claim 5.

7. The deposition rate per cycle during film formation is 0.1 nm / cycle or less. The film forming method according to claim 1.

8. A film formation material used in forming a hafnium-based film on a substrate by ALD, The material comprises a compound represented by the following formula [I]: Film deposition materials. Formula [I] LHf{N(C ２ H ５ ) ２ } ３ (L is a cyclopentadienyl group or a substituted cyclopentadienyl group.)

9. The substance represented by the formula [I] is CpHf{N(C ２ H ５ ) ２ } ３ is The film-forming material according to claim 8.

10. The hafnium-based film is a hafnium oxide-based film. The film-forming material according to claim 8.

11. Represented by the following formula [I] New compound. Formula [I] LHf{N(C ２ H ５ ) ２ } ３ (L is a cyclopentadienyl group or a substituted cyclopentadienyl group.)

12. The compound represented by the formula [I] is CpHf{N(C ２ H ５ ) ２ } ３ is The novel compound of claim 11.

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