Film deposition method, film deposition material, and new compound

Abstract

To provide a new compound rich in storage stability (heat stability), under a liquid condition at 25°C (1 atmosphere), with high vapor pressure (volatility), and suitable for uniform transportation.SOLUTION: To provide a compound expressed by L1ML23 (M is at least one selected from a group of Hf and Zr, L1 is a β-diketonate group, and L2 is a halogen group).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates, for example, to Group IV transition metals with specific ligands. [Background technology]

[0002] Group IV transition metal-containing films are used in semiconductor and electronic applications. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) have been applied as the main deposition techniques for producing thin films for semiconductor devices. These methods enable the achievement of conformal films (metals, metal oxides, metal nitrides, metal silicides, and similar films) through the chemical reaction of metal-containing compounds (precursors).

[0003] Japanese Patent No. 4562169 discloses tetrakis(dialkylamido)hafnium compounds such as Hf(NMe2)4 as Hf-based oxide gate insulating film materials.

[0004] Japanese Patent No. 4542807 discloses tetrakis(alkoxy)hafnium compounds such as Hf(OtBu)4 as hafnium silicate gate insulating film materials.

[0005] In Japanese Patent Publication No. 2004-137223, HfAl(OR 1 ) n (OR 2 ) 7-n has been disclosed.

[0006] In Japanese Patent Publication No. 2004-137222, HfAL (OR 1 ) n (OCR 2 R 3 AOR 4 ) 7-n has been disclosed.

[0007] In Patent No. 7329256, as an ALD raw material n PrCpHf(NMe2)3 has been disclosed.

[0008] J. Appl. Phys. 94, 3641-3647 (2003) discloses HfCl4 as an ALD raw material.

[0009] 2006 J. Electrochem. Soc, 153 F39 discloses Cp2HfCl2 as an ALD source. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4562169 [Patent Document 2] Patent No. 4542807 [Patent Document 3] JP 2004-137222 [Patent Document 4] JP 2004-137223 A [Patent Document 5] Patent No. 7329256 [Non-patent literature]

[0011] [Non-Patent Document 1] J.Appl.Phys.94,3641-3647(2003) [Non-patent document 2] 2006 J.Electrochem.Soc,153 F39 [Non-patent document 3] Z.anorg.allg.Chem.621(1995)2021-2024 Summary of the Invention [Problem to be solved by the invention]

[0012] Previously proposed Hf precursors in this field have not necessarily possessed sufficient properties. This is at least in part due to the low thermal stability of the Hf precursor, which causes decomposition during the transport process in the deposition process of the Hf-containing film, making it difficult to stably supply the precursor. At least in part due to the low thermal stability of the Hf precursor, it is difficult to raise the deposition temperature of the Hf-containing film in the deposition process, making it difficult to remove organic impurities from the Hf-containing film. At least in part due to the low vapor pressure (volatility) of the Hf precursor, it is difficult to transport the Hf precursor uniformly during the transport process to the deposition process of the Hf-containing film. At least in part due to the low vapor pressure (volatility) of the Hf precursor, it is difficult to transport the Hf-containing film uniformly during the transport process. At least in part due to the low vapor pressure (volatility) of the Hf precursor, it results in a slow (small) deposition rate of the Hf-containing film in the deposition process of the Hf-containing film.

[0013] Hafnium halide compounds such as HfCl4 disclosed in Non-Patent Document 1 are in a solid state at 25°C (1 atmosphere) and are difficult to transport uniformly in the process of transporting them to the deposition process of a Hf-containing film.

[0014] Tetrakis(dialkylamido)hafnium compounds such as Hf(NMe2)4 disclosed in Patent Document 1 have low thermal stability, and decompose during transport to the deposition process of Hf-containing films, making them difficult to transport uniformly.

[0015] Tetrakis(alkoxy)hafnium compounds such as Hf(OtBu)4 disclosed in Patent Document 2 are prone to clustering due to trace amounts of moisture, making them difficult to store stably.

[0016] Therefore, there remains a need in the art for Group IV transition metal precursors that have good shelf and thermal stability, high vapor pressure (volatility) and can be uniformly delivered to produce high quality, conformal Group IV transition metal-containing films by CVD and / or ALD processes.

[0017] The problem to be solved by the present invention is to provide a technique for forming a Group IV transition metal-containing film, particularly a technique for forming a Group IV transition metal-containing film by CVD and / or ALD using a Group IV transition metal compound as a precursor for forming the Group IV transition metal-containing film, which has excellent storage stability (thermal stability), is in a liquid state at 25°C (1 atmosphere), and has a high vapor pressure (volatility) suitable for uniform transport. For example, the present invention aims to provide a technique that is convenient for forming a Hf(Zr)-containing film, particularly a technique for forming a Hf(Zr)-containing film by CVD and / or ALD using a Hf(Zr) compound that has excellent storage stability (thermal stability), is in a liquid state at 25°C (1 atmosphere), has a high vapor pressure (volatility), and is suitable for uniform transport, as a precursor for forming the Hf(Zr)-containing film. [Means for solving the problem]

[0018] The present invention relates to a novel compound {structural formula (or structure) L 1 ML 2 3 (where M is Hf or Zr, and L 1 is a β-diketonate group, and L 2 is a halogen group.)}.

[0019] In particular, the L 1 However, preferably, the novel compound is a β-diketonate group having F.

[0020] In particular, the novel compound is one in which the β-diketonate group is preferably an acetylacetonate group.

[0021] In particular, the L 1 However, particularly preferred are novel compounds in which F is an acetylacetonate group.

[0022] In particular, the compound is a novel compound that is in a liquid state at 25°C (1 atmosphere).

[0023] In particular, the L 1 is a novel compound that has a 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac) group.

[0024] In particular, the L 2 is a novel compound in which

[0025] In particular, the L 1 is hfac, and said L 2 is a novel compound in which

[0026] In particular, it is a novel compound in which M is Hf.

[0027] In particular, it is a novel compound in which M is Zr.

[0028] The present invention provides compounds of formula (or structure) L suitable as CVD or / and ALD precursors for depositing Group IV transition metal-containing films. 1 ML 2 3 (where M is Hf or Zr, and L 1 is a β-diketonate group, and L 2 is a halogen group.

[0029] In particular, the Group IV transition metal-containing film is preferably deposited using a CVD or / and ALD technique.

[0030] In particular, the L 1 However, the film-forming material is preferably a β-diketonate group having F.

[0031] In particular, the β-diketonate group is preferably an acetylacetonate group in the film-forming material.

[0032] In particular, the L 1 However, a film-forming material having an acetylacetonate group containing F is particularly preferred.

[0033] In particular, the compound of the above structural formula is a film-forming material that is in a liquid state at, for example, 25° C. (1 atmosphere).

[0034] In particular, the L 1 is a film-forming material with an hfac group.

[0035] In particular, the L 2 The film-forming material is Cl.

[0036] In particular, the L 1 is hfac, and said L 2 The film-forming material is Cl.

[0037] In particular, the M is Hf and the L 1 is hfac, and said L 2 The film-forming material is Cl.

[0038] In particular, M is Zr and L 1 is hfac, and said L 2 The film-forming material is Cl.

[0039] The present invention provides a compound having the formula (or structure) L 1 ML 2 3 (where M is Hf or Zr, and L 1 is a β-diketonate group, and L 2 is a halogen group.) into a film formation chamber, and a film containing a Group IV transition metal is formed on a substrate placed in the film formation chamber.

[0040] In particular, the present invention relates to a film formation method using a Group IV transition metal precursor compound represented by the above structural formula, in which CVD and / or ALD techniques are used.

[0041] In particular, the L 1 Preferably, the film-forming method is characterized in that the β-diketonate group has F.

[0042] In particular, the β-diketonate group is preferably an acetylacetonate group.

[0043] In particular, the L 1 However, a film-forming method in which an acetylacetonate group having F is used is particularly preferred.

[0044] In particular, the film-forming method is one in which the compound is in a liquid state at 25° C. (1 atmosphere).

[0045] In particular, the L 1 This is a film formation method in which the film is an hfac group.

[0046] In particular, the L 2 This is a film formation method in which the base is Cl.

[0047] In particular, the L 1 is hfac, and said L 2 is a film formation method in which Cl is used.

[0048] In particular, the M is Hf and the L 1 is hfac, and said L 2 is a film formation method in which Cl is used.

[0049] In particular, M is Zr and L 1 is hfac and L 2 is a film formation method in which Cl is used.

[0050] Preferred Group IV transition metal-containing films include, but are not limited to, Group IV transition metal films, Group IV transition metal oxide films, Group IV transition metal nitride films, and Group IV transition metal oxynitride films. [Effects of the Invention]

[0051] The Group IV transition metal precursor proposed by the present invention, for example, a compound that is in a liquid state at 25°C (1 atmosphere), can be transported more uniformly in the process of transporting it to the deposition process of a Group IV transition metal-containing film, and since it is a compound with excellent thermal stability, it can be transported more uniformly without decomposition in the process of transporting it to the deposition process of a Group IV transition metal-containing film, and can result in a high-quality, conformal Group IV transition metal-containing film. [Brief explanation of the drawings]

[0052] [Figure 1] Magnetic resonance analysis (NMR) of (hfac)HfCl3 [Figure 2] Thermogravimetric analysis (TG-DTA) of (hfac)HfCl3 [Figure 3] NMR diagram of (hfac)2HfCl2 [Figure 4] TG-DTA diagram of (hfac)2HfCl2 [Figure 5] NMR diagram of (thd)HfCl3 [Figure 6] TG-DTA diagram of (thd)HfCl3 [Figure 7] TG-DTA comparison diagram of Synthesis Examples 1 and 2 and Comparative Synthesis Example 1 [Figure 8] FIG. 1 is a schematic view of a film forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0053] The following detailed description provides preferred exemplary embodiments only and is not intended to limit the scope, applicability, or configuration of the present invention. Rather, it provides an enabling description for those skilled in the art for implementing preferred exemplary embodiments of the present invention. Various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the present invention, as defined by the appended claims.

[0054] For example, the Group IV transition metal compound of the present invention is sometimes described as a complex, but because it is suitable for use in CVD and / or ALD, it is sometimes described as a precursor. Either notation can be considered to refer to the same thing.

[0055] The CVD is not limited to CVD in the narrow sense, but can be considered to include CVD in the broad sense and similar CVDs. Similarly, the ALD is not limited to ALD in the narrow sense, but can be considered to include ALD in the broad sense and similar ALDs. Examples include pulsed CVD, laser CVD, cyclic CVD (CCVD), metalorganic CVD (MOCVD), plasma-enhanced CVD (PECVD), high-density PECVD, photon-assisted CVD, plasma-photon-assisted CVD (PPECVD), thermal chemical vapor deposition, low-temperature chemical vapor deposition, chemically assisted vapor deposition, hot-filament chemical vapor deposition, CVD of liquid polymer precursors, deposition from supercritical fluids, low-energy CVD (LECVD), and plasma-enhanced ALD (PEALD). Other examples include CVD and ALD that employ radiation (X-rays, electron beams, electromagnetic waves, or light).

[0056] The Group IV transition metal-containing film can be considered to refer to a metal film (a film consisting only of a Group IV transition metal), an alloy film (an alloy film containing a Group IV transition metal), an oxide film (an oxide film or silicon oxide film containing a Group IV transition metal), a nitride film (a nitride film or silicon nitride film containing a Group IV transition metal), an oxynitride film (an oxynitride film containing a Group IV transition metal), a carbide film (a carbide film containing a Group IV transition metal), a silicon film (a silicon film containing a Group IV transition metal), and other films of various compositions, and includes any type of film as long as it contains Hf (and / or Zr) as one of its components.

[0057] The first invention is a novel compound represented by the following general formula (I).

[0058] General formula (I) L 1 ML 2 3 (where M is Hf or Zr, and L 1 is a β-diketonate group, and L 2 is a halogen group.)

[0059] Preferably, the L 1 is a β-diketonate group having F. When it was a β-diketonate group not having F, the compound represented by the general formula (I) was a solid.

[0060] Preferably, the β-diketonate group is an acetylacetonate group, including partially substituted acetylacetonate groups, and particularly preferably a 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac) group.

[0061] Examples of the compound include (hfac)HfCl3, (hfac)HfBr3, (hfac)HfI3, (hfac)ZrCl3, (hfac)ZrBr3, (hfac)ZrI3, etc., but are not limited to these, and may also be (hfac)HfCl2Br.

[0062] More preferably, the L 2 is Cl.

[0063] It is particularly preferable that the compound is in a liquid state at room temperature (for example, 25°C (1 atmosphere)) and has a high vapor pressure (volatility). 1 is hfac and L 2 is Cl. In the following examples, only Hf is disclosed as M, but it will be easily understood by those skilled in the art that Hf can be replaced with Zr.

[0064] A typical halogen compound, HfCl4, is a solid at 25°C (1 atm) and has a low vapor pressure (volatility). For the compound to be a liquid (for example, at 25°C (1 atm)), it is important that the group bonded to the Group IV transition metal M has a structure containing one β-diketonate group (wherein this β-diketonate group contains F) and three halogens. Among these, hfac was the most preferred β-diketonate group.

[0065] It is well known that when decomposition occurs during the deposition of a Group IV transition metal-containing film, impurities, particularly carbon (C), are likely to be introduced into the film. Therefore, in order to deposit a high-purity Group IV transition metal-containing film, it is important not only to deposit the film at a higher temperature without decomposing the Group IV transition metal precursor, but also to minimize the organic components contained in the Group IV transition metal precursor, i.e., the number of substituents bonded to the Group IV transition metal M (the number of alkyl groups in the case of alkyl groups) and / or the number of carbon atoms contained in the substituents. Therefore, it was important that the group bonded to the Group IV transition metal M had a structure containing one β-diketonate group (provided that this β-diketonate group contained F) and three halogens. Among these, hfac was the most preferable β-diketonate group.

[0066] The second invention is a film-forming material for a Group IV transition metal film used to form a Group IV transition metal-containing film. The material is at least a compound represented by the general formula (I) (the compound described above). The term "at least" means that the compound represented by the general formula (I) may be used alone or in combination with other materials (compounds). In other words, the material may be in the form of a composition.

[0067] The third invention is a method for forming a Group IV transition metal-containing film using the above-mentioned film-forming material as a precursor. CVD or ALD techniques are preferably used for film formation in the present invention.

[0068] Generally, in the field of metal-containing film deposition, substrate temperature is an important process variable. Typical substrate temperatures are about 150°C to about 550°C. Higher substrate temperatures can promote faster film growth rates. Therefore, it is desirable to find Group IV transition metal precursors that can deposit Group IV transition metal-containing films at higher temperatures without decomposition. Compounds represented by the general formula (I) satisfy this need.

[0069] It is generally recognized in the field of metal-containing film deposition that precursors that are liquid under the process conditions for metal-containing film deposition are preferable to precursors that are solid under the process conditions for metal-containing film deposition. Liquid precursors can transport precursors more uniformly during the metal-containing film deposition process compared to solid precursors. In one embodiment, a carrier gas is bubbled through the metal-containing film precursor under suitable process conditions. Bubbling a gas through a liquid is an effective means of providing a longer gas-liquid contact time and a larger gas-liquid contact area, with the goal of achieving a gas flow saturated with vaporized liquid precursor. Achieving a saturated carrier gas maximizes the precursor transport rate and is advantageous for operating a metal-containing film deposition process. The compound represented by the general formula (I) satisfies the above requirements.

[0070] [Example] The present invention will be described in more detail below, but the following description is merely a preferred exemplary embodiment and is not intended to limit the present invention. Various modifications are also included as long as they do not depart from the spirit and scope of the present invention as defined in the claims.

[0071] [Example 1] [Synthesis Example 1: (hfac)HfCl3] The synthesis was carried out under a nitrogen atmosphere. 9.6 g of HfCl4 was slowly added to a vessel containing 10 g of Hf(hfac)4 and 100 ml of dichloromethane. The mixture was stirred in the vessel. The vessel was heated to 60°C and heated and stirred for 7 hours. After this, the heating was stopped and the temperature in the vessel gradually returned to room temperature. Stirring continued during this time. After stirring at room temperature, the solvent of the resulting mixture was removed by vacuum distillation, and the resulting crude product was purified by distillation to obtain a pale yellow liquid.

[0072] 19The F-NMR spectrum (see Figure 1) indicates that the resulting pale yellow liquid is (hfac)HfCl3.

[0073] The volatility of the compound is 91.85%, and the temperature at which the weight loss rate reaches 50% (T 50 ) was 152.3°C (see Figure 2). This material has high vaporizability and a high vapor pressure. It is a suitable precursor for forming Hf-containing films.

[0074] [Comparative Example 1] [Comparative synthesis example 1: (hfac)2HfCl2] The synthesis was carried out under a nitrogen atmosphere. 6.4 g of HfCl4 was slowly added to a vessel containing 20 g of Hf(hfac)4 and 200 ml of dichloromethane. The mixture was stirred in the vessel. The vessel was heated to 65°C and heated and stirred for 4 hours. After this, the heating was stopped and the temperature in the vessel gradually returned to room temperature. Stirring continued during this time. After stirring at room temperature, the solvent in the resulting mixture was removed by vacuum distillation, and the resulting crude product was purified by sublimation to yield a yellow-white solid.

[0075] 19 The F-NMR spectrum (see Figure 3) indicates that the resulting yellow-white solid is (hfac)2HfCl2.

[0076] The compound is a material with multi-stage weight loss (see Figure 4). It is difficult to say that it is a precursor that can be uniformly supplied in the transport process in the deposition process of Hf-containing films. It is difficult to say that it is a suitable precursor for forming Hf-containing films.

[0077] [Example 2] [Synthesis Example 2: (thd)HfCl3]thd(1,1,1,5,5,5-hexamethyl-2,4-pentanedionate) Synthesis was carried out in the same manner as in Example 1, except that Hf(hfac)4 was replaced with Hf(thd)4. A white solid was obtained by sublimation purification.

[0078] 1 The H-NMR spectrum (see Figure 5) indicates that the resulting white solid is (thd)HfCl3.

[0079] The volatilization rate of the compound was 96.41% (see Figure 6). 50 It has a high temperature of 311.3°C, poor vaporization properties, and a low vapor pressure, making it difficult to say that it is a suitable precursor for forming Hf-containing films.

[0080] The state of the novel compounds of Examples 1 and 2 (Synthesis Examples 1 and 2) and the comparative compound (Comparative Synthesis Example 1) as determined by visual observation at 25°C (1 atmosphere), and T 50 The temperatures are shown in Table 1. Table-1 JPEG2025133245000002.jpg34170

[0081] The (hfac)HfCl3 (Synthesis Example 1) is a liquid at 25°C (1 atmosphere), and T 50 The temperature is 152.3°C. The (hfac)2HfCl2 (Comparative Synthesis Example 1) is a solid at 25°C (1 atm), and the TG curve shows a multi-stage weight loss. 50 The temperature cannot be clearly distinguished. The multi-step weight loss in the TG curve indicates thermal transformation of the compound structure (e.g., decomposition), making it undesirable as a stable and uniform supply option in the deposition process of metal-containing films. The two compounds differ only in the number of β-diketonate groups (hfac) and halogen groups (Cl) bonded to Hf. No one could have predicted that this difference would cause the difference between a liquid and a solid at 25°C (1 atm) and the difference in the behavior of the TG curve, i.e., the difference in volatility. This was discovered for the first time by the present inventors. This indicates that (hfac)HfCl3 may be a better option than (hfac)HfCl2 when used as a precursor during transport in the deposition process of metal-containing films.

[0082] The (thd)HfCl3 (Synthesis Example 2) is a solid at 25°C (1 atmosphere), and T50 The temperature is 311.3°C. (hfac)HfCl3 and (thd)HfCl3 have the same number of Cl bonded to Hf, but the only difference is the element contained in the β-diketonate group, i.e., F in hfac and H in thd. This difference causes the difference between liquid and solid at 25°C (1 atmosphere), and T 50 No one would have predicted that such a clear difference in temperature, and therefore in volatility, would occur. This finding was first discovered by the present inventors, and indicates that (hfac)HfCl3 may be a better choice than (thd)HfCl3 for use as a precursor during transport in the deposition process of metal-containing films.

[0083] HfCl4, in which all four substituents are Cl, is a solid at 25°C (1 atm), and T 50 The temperature is 258.6°C. (hfac)HfCl3 and HfCl4 differ only in the presence or absence of a single β-diketonate group, i.e., hfac, bonded to Hf. This difference causes the difference between liquid and solid at 25°C (1 atmosphere), and T 50 No one would have predicted that such a clear difference in temperature, and therefore in volatility, would occur. This finding was first discovered by the present inventors, and indicates that (hfac)HfCl3 may be a better choice than HfCl4 as a precursor during transport in the deposition process of metal-containing films.

[0084] [Example 3] FIG. 8 is a schematic diagram of a film forming apparatus, in which 1 is a vessel, 2 is a vaporizer, 3 is a heater, 4 is a substrate, 5 is a decomposition reactor, 6 is a heater, and 7 is a vacuum pump. 8, an Hf-based film was formed on a substrate 5. That is, an Hf-based thin film was formed using the novel compound (hfac)HfCl3 (Synthesis Example 1) as a precursor. The precursor in a container 1 was supplied to a vaporizer by a pressurized gas (e.g., nitrogen gas), and the precursor vaporized by the vaporizer was introduced into a decomposition reactor 5, whereby an Hf-based film was formed on a heated substrate 4. As a result, it was confirmed that the Hf-based film obtained by the above method had excellent inner surface uniformity and was a highly pure film by X-ray photoelectron spectroscopy (XPS).

[0085] [Example 4] In Example 3, the film was formed by chemical vapor deposition, while in Example 4, the film was formed by atomic controlled deposition. As a result, the formation of a highly pure film with excellent internal uniformity was confirmed by XPS.

[0086] It will be understood that many further variations in the details of materials, steps, components, etc., described and shown herein to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.

[0087] It is not intended that the present invention be limited to the foregoing examples and / or embodiments.

Claims

1. A film forming method, comprising: L １ ML ２ ３ (M is Hf or Zr, L １ is a β-diketonate group having F, and L ２ is a halogen.) is supplied to a film-forming chamber to form a film on a substrate. Film formation method.

2. Said L １ is an acetylacetonate group having F 10. The method of claim 1.

3. Said L １ is hfac The method of claim 2.

4. Said L １ is hfac, and L ２ is Cl The method of claim 3.

5. Said L ２ is Cl 10. The method of claim 1.

6. M is Hf The method of claim 1 or claim 2.

7. M is Zr The method of claim 1 or claim 2.

8. A film-forming material, The material is L １ ML ２ ３ (M is Hf or Zr, L １ is a β-diketonate group having F, and L ２ is a halogen.) Film deposition materials.

9. Said L １ is an acetylacetonate group having F The film-forming material according to claim 8.

10. Said L １ is hfac The film-forming material according to claim 8.

11. Said L ２ is Cl The film-forming material according to claim 8.

12. Said L １ is hfac, L ２ is Cl The film-forming material according to claim 8.

13. M is Hf The film-forming material according to claim 8.

14. M is Zr The film-forming material according to claim 8

15. L １ ML ２ ３ (M is at least one selected from the group consisting of Hf and Zr. １ is a β-diketonate group. ２ is a halogen.) New compound.

16. Said L １ is a diketonate group having F 16. The novel compound of claim 15.

17. Said L １ is hfac 16. The novel compound of claim 15.

18. Said L １ is hfac, L ２ is Cl 16. The novel compound of claim 15.

19. Said L ２ is Cl 16. The novel compound of claim 15.

20. M is Hf 16. The novel compound of claim 15.

21. M is Zr 16. The novel compound of claim 15.

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