Group V metal precursor and application thereof in thin film deposition

Abstract

The invention provides a group V metal precursor and application thereof in thin film deposition, the structure of the group V metal precursor is M (NR0) L [OCR1R2 (CR3R4) XNR5R6] 2, M is V or Nb; r0 is selected from C1-C5 alkyl groups; r1 to R6 are selected from H, C1-C8 alkyl groups or C1-C5 alkoxy groups, and R1, R2, R3 and R4 are not H at the same time; x is an integer greater than or equal to 0; and L is selected from any one of a substituted or non-substituted cyclopentadienyl group, a diaza-dienyl group or a dienyl group. According to the V-group metal precursor, an ALD window can be widened, the deposition requirement at the higher temperature can be met, the film quality of the prepared thin film can be improved, and the thin film has the lower C and N impurity content and the lower surface roughness.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film deposition, and relates to a Group V metal precursor and its application in thin film deposition. Background Art

[0002] Group V metal oxides such as Nb 2 O 5 It has a wide band gap (band gap = 3.6eV), a high refractive index (n = 2.4), and a high dielectric constant (29-200), so it can be used as a promising transparent oxide semiconductor and is widely used in capacitor dielectric layers, anti-reflection films, catalyst support oxides, etc. In DRAM applications, Nb 2 O 5 It has gradually attracted people's interest to replace the widely known SrTiO with a higher dielectric constant. 3 or Al-doped TiO 2 film.

[0003] In recent years, halogen-free and thermally stable metallic Nb precursors have been gradually developed to achieve higher quality Nb 2 O 5 Atomic layer deposition. Such precursor products include: tBuN=Nb(NEt 2 ) 3 (TBTDEN), tBuN=Nb(NEtMe) 3 (TBTEMN), t-amylN=Nb(O t Bu) 3 Among them, TBTDEN and TBTEMN have been proven to be liquid precursor materials with good vapor pressure and a wide ALD window (150-300°C); the decomposition temperature can reach above 300°C. Although this type of imine precursor has good thermal stability, it still cannot meet the current requirements for higher thermal stability of metal Nb precursors.

[0004] Later, Air Liquide developed (tert-butylimino)bis(dimethylamino)(cyclopentadienyl)niobium (CpNb( t BuN)(NMe 2 ) 2 ) as an improved precursor of metal Nb imine precursor, and disclosed its application in thin film deposition in 2014100085546. This type of precursor has higher thermal stability, but it has high C and N content and high roughness in thin film deposition, which affects the performance of the film. UP CHEMICAL also disclosed the precursor structure (R 1 Cp)(R 2Cp)Nb( t Bu 3 , where R 1 and R 2 are independently hydrogen, or C1-3 straight or branched chain alkyl, R 3 It is a substituted or unsubstituted straight or branched C1-10 alkyl group, or a substituted or unsubstituted C 3-10 cycloalkyl group. Although the precursor has high thermal stability, it has high viscosity (120 cP, 25°C) and low vapor pressure (0.5 Torr, 110°C), which is not convenient for deposition operations such as ALD and CVD. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a Group V metal precursor and its application in thin film deposition. The Group V metal precursor of the present invention can broaden the ALD window, meet the deposition requirements of higher temperatures, and improve the film quality of the prepared thin film, so that it has less C and N impurity content and lower surface roughness.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a Group V metal precursor having a structure of M(NR 0 )L[OCR 1 R 2 (CR 3 R 4 ) X NR 5 R 6 ] 2 ;

[0008] Where, M is V or Nb; R 0 An alkyl group selected from C1-C5; R 1 -R 6 is selected from H, C1-C8 alkyl or C1-C5 alkoxy, R 1 , R 2 , R 3 , R 4 They are not H at the same time; x is an integer ≥0 (for example, 0, 1, 2, 3, 4, 5, etc.); L is selected from any one of substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted diazadienyl or substituted or unsubstituted dienyl, and the substituent in the substituted group is selected from any one of C1-C5 alkyl, C1-C5 alkoxy or C1-C5 silyl or a combination of at least two of them.

[0009] In the present invention, the C1-C5 alkyl group may be a C1, C2, C3, C4 or C5 alkyl group; the C1-C8 alkyl group may be a C1, C2, C3, C4, C5, C6, C7 or C8 alkyl group; the C1-C5 alkoxy group may be a C1, C2, C3, C4 or C5 alkoxy group, and the C1-C5 silyl group may be a C1, C2, C3, C4 or C5 silyl group.

[0010] Furthermore, R 0 It is a C3-C5 alkyl group.

[0011] Furthermore, R 1 -R 6 is selected from H, C1-C8 alkyl, R 1 , R 2 , R 3 , R 4 Not H at the same time; x is an integer ≥1.

[0012] Preferably, R 0 It is any one of n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; more preferably tert-butyl.

[0013] Furthermore, R 5 and R 6 Independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl or hexyl.

[0014] Preferably, x is an integer of 0-3, such as 0, 1, 2 or 3.

[0015] Furthermore, the partial structure of the Group V metal precursor can be listed as follows:

[0016]

[0017]

[0018]

[0019]

[0020] Wherein, M is V or Nb, preferably Nb, R is H or a C1-C5 straight or branched alkane group, t Bu represents tert-butyl.

[0021] In a preferred embodiment, the precursor is CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 or CpNb( tBuN)(OCH(Me)CH 2 NMe 2 ) 2 , where Cp represents cyclopentadienyl, Me represents methyl, and Et represents ethyl, t Bu represents tert-butyl, and its structures are:

[0022]

[0023] In another aspect, the present invention provides a method for preparing the Group V metal precursor as described above, the preparation method comprising the following steps:

[0024] M(NR 0 )L(NR 2 ) 2 and ligand HOCR 1 R 2 (CR 3 R 4 ) X NR 5 R 6 Reaction to obtain the Group V metal precursor.

[0025] Preferably, the specific operation of the reaction is: M(NR 0 )L(NR 2 ) 2 Mix with solvent and cool to below 0℃, add ligand HOCR 1 R 2 (CR 3 R 4 ) X NR 5 R 6 Reaction to obtain the Group V metal precursor.

[0026] Preferably, the solvent is selected from any one of n-hexane, n-pentane, toluene, xylene, trimethylbenzene, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether or methyl tert-butyl ether, or a combination of at least two thereof.

[0027] Preferably, the M(NR 0 )L(NR 2 ) 2 and ligand HOCR 1 R 2 (CR 3 R 4 ) X NR 5 R 6 The molar ratio is 1:2-10, for example 1:2, 1:3, 1:4, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:9 or 1:10, etc.

[0028] Preferably, the reaction is carried out under the protection of a protective gas, and the protective gas is preferably nitrogen.

[0029] Preferably, the reaction temperature is -30°C to 40°C, for example -30°C, -20°C, -10°C, -5°C, 0°C, 10°C, 20°C, 30°C or 40°C, and the reaction time is 0.1-20h, for example 0.1h, 0.5h, 1h, 2h, 4h, 5h, 8h, 10h, 12h, 15h, 18h or 20h.

[0030] Preferably, after the reaction is completed, low boiling points are removed to obtain a crude product, and the crude product is purified to obtain a purified product.

[0031] In the present invention, the selectable purification method includes but is not limited to at least one of filtration, distillation, adsorption, crystallization, extraction or ion exchange.

[0032] On the other hand, the present invention also provides a precursor composition, which comprises at least one of the Group V metal precursors.

[0033] On the other hand, the present invention also provides a method for depositing a thin film, comprising the following steps: depositing the Group V metal precursor onto a substrate surface to obtain a thin film.

[0034] In the present invention, the selectable deposition methods include at least one of chemical vapor deposition (CVD), atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), remote plasma atomic layer deposition (RPALD), spray atomic layer deposition (SprayALD), etc., preferably ALD.

[0035] The present invention has no strict requirements on the substrate, and the substrates that can be selected include Si-based, Cu-based, Ti-based, Mo-based, etc.

[0036] In the present invention, the thin film is a V-containing film or a Nb-containing film.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The Group V metal precursor of the present invention broadens the ALD window and can meet the deposition requirements of higher temperatures. For example, according to experimental results, CpNb(tBuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 The decomposition temperature is >400°C and the ALD window is 250-400°C.

[0039] The Group V metal precursor of the present invention has low viscosity and high vapor pressure, is easy to carry out ALD deposition operation and can improve the film quality such as purity and roughness; and is different from the currently used niobium source (tert-butylimino)bis(dimethylamino)(cyclopentadienyl)niobium [CpNb(tBuN)(NMe 2 ) 2 】Compared with the precursor, this precursor shows less C and N impurity content and lower surface roughness in thin film deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The precursor prepared in Example 1 1 H NMR characterization chart.

[0041] Figure 2 This is the thermogravimetric curve of the precursor prepared in Example 1.

[0042] Figure 3 The metal Nb prepared in Example 6 2 O 5 Atomic force microscopy image of the film.

[0043] Figure 4 The metal Nb prepared in Comparative Example 1 2 O 5 Atomic force microscopy image of the film.

[0044] Figure 5 This is a graph showing the relationship between deposition temperature and GPC (deposition rate) for thin film deposition of the precursor prepared in Example 1.

[0045] Figure 6 This is a relationship diagram between the deposition temperature and GPC (deposition rate) of the thin film deposition of the precursor prepared in Comparative Example 1.

[0046] Figure 7 This is the result of XPS elemental analysis of the film prepared in Example 6.

[0047] Figure 8 This is the result of XPS elemental analysis of the film prepared in Comparative Example 1.

[0048] Fig. 9 This is the process saturation curve for thin film deposition in Example 6.

[0049] Fig.10 This is the process saturation curve of thin film deposition in Comparative Example 1. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] Embodiment 1:

[0052] This embodiment provides a Group V metal precursor CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 , the structure is:

[0053]

[0054] The preparation method is as follows: under nitrogen protection, CpNb( t BuN)(NMe 2 ) 2 200g of ethanol and 1L of n-hexane were mixed, the system was cooled to -20°C, and the ligand HOC(Me)(Et)CH 2 NMe 2 182g, react for 8h, remove low boiling points, and distill the residue under reduced pressure to obtain CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 266g, product yield is 86%.

[0055] Product 1 H NMR spectrum Figure 1 As shown, 1 H NMR (C 6 D 6 , 400MHz) characterization: δ0.96-1.03 (m, 6H, CH 2 CH 3 ),1.22(s,9H,N(CH 3 ) 3 ),1.34-1.38(d,6H,CH 3 ),1.63-1.83(m,4H,CH 2 CH 3 ),2.37-2.29(m,4H,NCH 2 ),2.32(s,12H,N(CH 3 ) 2 ),6.24-6.25(t,4H,C 5 H 4 ).

[0056] Viscosity: 37 cP @ 25 °C; The viscosity test was conducted using an IKA ROTAVISC lo-vi rotational viscometer with an SP-1 rotor, and the values ​​were rounded off.

[0057] Vapor pressure: 0.91Torr@105℃; Vapor pressure test is in accordance with GB / T 35930-2018 Determination of saturated vapor pressure by thermogravimetric method.

[0058] Figure 2 This is the thermogravimetric curve of the precursor. It can be seen from the figure that its mass loss is 0.67%.

[0059] Embodiment 2:

[0060] This embodiment provides a Group V metal precursor CpNb( t BuN)(OCH(Me)CH 2 NMe 2 ) 2 , the structure is:

[0061]

[0062] The preparation method is as follows: under nitrogen protection, CpNb( t BuN)(NMe 2 ) 2 200g of HOCH(Me)CH 2 NMe 2 136g, react for 2h, remove low boiling points, and distill the residue under reduced pressure to obtain CpNb( t BuN)(OCH(Me)CH 2 NMe 2 ) 2 226g, product yield is 83%, viscosity is 29cP@25℃.

[0063] Embodiment 3:

[0064] This embodiment provides a Group V metal precursor CpNb( t BuN)(OCH(Me)CH(Et)NMe 2 ) 2 , the structure is:

[0065]

[0066] The preparation method is as follows: under nitrogen protection, CpNb( t BuN)(NMe 2 ) 2200g, 1.5L of n-hexane, cool the system to 0℃, add ligand HOCH(Me)CH(Et)NMe under stirring 2 182g, react for 8h, remove low boiling points, and distill the residue under reduced pressure to obtain CpNb( t BuN)(OCH(Me)CH(Et)NMe 2 ) 2 242g, product yield is 78%, viscosity is 44cP@25℃.

[0067] Embodiment 4:

[0068] This embodiment provides a Group V metal precursor CpNb( t BuN)(OCMeEtCH 2 N i Pr 2 ) 2 , the structure is:

[0069]

[0070] The preparation method is as follows: under nitrogen protection, CpNb( t BuN)(NMe 2 ) 2 200g of ethanol and 1L of n-hexane were mixed, the system was cooled to 0°C, and the ligand HOCH(Me)(Et)CH 2 N i Pr 2 231g, reacted for 8h, removed low boiling points, and the residue was distilled under reduced pressure to obtain CpNb( t BuN)(OC(Me)(Et)CH 2 N i Pr 2 ) 2 274g, product yield is 72%, viscosity is 80cP@25℃.

[0071] Embodiment 5:

[0072] This embodiment provides a Group V metal precursor CpNb( i PrN)(OCMeEtCH 2 NMe 2 ) 2 , the structure is:

[0073] in i Pr is isopropyl.

[0074] The preparation method is as follows: under nitrogen protection, CpNb( i PrN)(NMe2 ) 2 200g of ethanol and 1L of n-hexane were mixed, the system was cooled to 0°C, and the ligand HOCH(Me)(Et)CH 2 NMe 2 182g, react for 10h, remove low boiling points, and distill the residue under reduced pressure to obtain CpNb( i PrN)(OC(Me)(Et)CH 2 NMe 2 ) 2 151 g, product yield 48%; viscosity 27 cP@25°C.

[0075] Embodiment 6:

[0076] This embodiment provides a method of using CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 As a precursor to deposit Nb 2 O 5 The method of the thin film comprises the following steps:

[0077] (1) The niobium precursor CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 The source bottle is heated to 110°C, the precursor transport pipeline and valve are heated to 120°C, the ALD chamber temperature is heated to 300°C, and the ALD chamber is evacuated to 10Pa;

[0078] (2) CpNb( t BuN)(OC(Me)(Et)CH 2 NMe 2 ) 2 The vapor is introduced for 5 seconds, and the precursor vapor forms chemical adsorption on the substrate surface;

[0079] (3) The unadsorbed precursors and reaction byproducts were purged with inert gas for 15 seconds;

[0080] (4) Introduce the reactive gas O into the ALD chamber through the carrier gas 3 , O 3 The flow rate is 100 sccm, O 3 Complete reaction with the precursor adsorbed on the substrate, the oxidation duration is 1s;

[0081] (5) Remove the unreacted O3 , and the reaction byproducts were purged clean, the purging time was 15s, and a single layer of Nb was deposited on the substrate surface 2 O 5 film;

[0082] (6) Repeat steps (2)-(5) for 500 cycles to form the Nb 2 O 5 film.

[0083] The XPS elemental analysis results are as follows Figure 7 As shown, XPS elemental analysis (Thermo 250xi) shows that the deposited metal Nb 2 O 5 In the film, the impurity C content is 0.58%, and the N content is 0.03%. The specific data are shown in the table below:

[0084] Table 1

[0085] element Nb3d O1s C1s N1s O / Nb Element content% 29.91 69.48 0.58 0.03 2.32

[0086] AFM (Bruker) analysis (see attached Figure 3 ), the film surface roughness is

[0087] Figure 5 The relationship diagram between deposition temperature and GPC (deposition amount) for thin film deposition of the precursor prepared in Example 1 shows that the ALD deposition window is 250-400°C.

[0088] Fig. 9 is the process saturation curve of thin film deposition in this embodiment, Fig. 9 It can be seen that the precursor reaches saturation at about 5s of pulse, and the deposition rate (GPC) at saturation is / cycle, after which the deposition rate and film uniformity (NU) can remain basically stable.

[0089] Embodiment 7:

[0090] It is basically the same as Example 6, except that the precursor is CpNb ( t BuN)(OCH(Me)CH(Et)NMe 2 ) 2 .

[0091] XPS element analysis shows that the deposited metal Nb 2 O 5 In the film, the impurity C content is 0.60%, and the N content is 0.01%. The specific data are shown in the table below:

[0092] Table 2

[0093] element Nb3d O1s C1s N1s O / Nb Element content / % 29.85 69.54 0.60 0.01 2.35

[0094] Example 8

[0095] It is basically the same as Example 6, except that the precursor is CpNb ( t BuN)(OCMeEtCH 2 N i Pr 2 ) 2 .

[0096] XPS element analysis shows that the deposited metal Nb 2 O 5 In the film, the impurity C content is 0.80%, and the N content is 0.03%. The specific data are shown in the table below:

[0097] Table 3

[0098] element Nb3d O1s C1s N1s O / Nb Element content / % 29.96 69.21 0.80 0.03 2.31

[0099] Example 9

[0100] It is basically the same as Example 6, except that the precursor is CpNb ( i PrN)(OCMeEtCH 2 NMe 2 ) 2 .

[0101] XPS element analysis shows that the deposited metal Nb 2 O 5 In the film, the impurity C content is 1.03%, and the N content is 0.07%. The specific data are shown in the table below:

[0102] Table 4

[0103] element Nb3d O1s C1s N1s O / Nb Element content / % 29.44 69.46 1.03 0.07 2.36

[0104] Comparative Example 1

[0105] A method using CpNb( t BuN)(NMe 2 ) 2 As a precursor for ALD deposition of Nb 2 O 5 Thin film method:

[0106] (1) The niobium precursor CpNb ( t BuN)(NMe 2 ) 2 Heat to 60°C, heat the precursor transport pipeline and valve to 120°C, heat the ALD chamber temperature to 300°C, and evacuate the ALD chamber to 10Pa;

[0107] (2) CpNb( t BuN)(NMe 2 ) 2 The vapor is introduced for 5 seconds, and the precursor vapor forms chemical adsorption on the substrate surface;

[0108] (3) The unadsorbed precursors and reaction byproducts were purged with inert gas for 15 seconds;

[0109] (4) Introduce the reactive gas O into the ALD chamber through the carrier gas 3 , O 3 The flow rate is 100 sccm, O 3 It reacts completely with the ruthenium precursor adsorbed on the substrate, and the oxidation duration is 1s;

[0110] (5) Remove the unreacted O 3 , and the reaction byproducts were purged clean, the purging time was 15s, and a single layer of Nb was deposited on the substrate surface 2 O 5 film;

[0111] (6) Repeat steps (2)-(5) for 500 cycles to form the Nb 2 O 5 film.

[0112] The XPS elemental analysis results are as follows Figure 8 As shown, XPS element analysis shows that the deposited metal Nb 2 O 5 In the film, the impurity C content is 2.37% and the N content is 0.98%. See the table below for specific data.

[0113] Table 5

[0114] element Nb3d O1s C1s N1s O / Nb Element content / % 29.66 66.99 2.37 0.98 2.26

[0115] AFM analysis (see Figure 4 ), the film surface roughness is

[0116] Figure 6 To use CpNb( t BuN)(NMe 2 ) 2 From the relationship diagram between the deposition temperature and GPC (deposition amount) of the thin film deposition as a precursor, it can be seen that its ALD deposition window is 250-350°C.

[0117] Fig.10 is the process saturation curve of thin film deposition in this comparative example, Fig.10 It can be seen that the precursor reaches saturation at about 3s of pulse, and the deposition rate (GPC) at saturation is

[0118] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the Group V metal precursor of the present invention and its application in thin film deposition, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A Group V metal precursor, characterized in that: The Group V metal precursor structure is M(NR0)L[OCR1R2(CR3R4) X NR5R6]2; Wherein, M is V or Nb; R0 is selected from C1-C5 alkyl; R1-R6 is selected from H, C1-C8 alkyl or C1-C5 alkoxy, and R1, R2, R3, and R4 are not H at the same time; x is an integer ≥0; L is selected from any one of substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted diazadienyl or substituted or unsubstituted dienyl, and the substituent in the substituted group is selected from any one of C1-C5 alkyl, C1-C5 alkoxy or C1-C5 silyl or a combination of at least two of them.

2. The Group V metal precursor according to claim 1, characterized in that R0 is a C3-C5 alkyl group; R1-R6 are selected from H and C1-C8 alkyl, R1, R2, R3 and R4 are not H at the same time; x is an integer ≥1.

3. The Group V metal precursor according to claim 1 or 2, characterized in that: R0 is any one of n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl; more preferably tert-butyl.

4. The Group V metal precursor according to any one of claims 1 to 3, characterized in that: R5 and R6 are independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl or hexyl; Preferably, x is an integer from 0 to 3.

5. The Group V metal precursor according to any one of claims 1 to 4, characterized in that: The Group V metal precursor is any one of the following compounds: Wherein, M is V or Nb, preferably Nb, R is H or a C1-C5 straight or branched alkane group, t Bu represents tert-butyl.

6. The method for preparing a Group V metal precursor according to any one of claims 1 to 5, comprising the following steps: M(NR0)L(NR2)2 and ligand HOCR1R2(CR3R4) X NR5R6 reaction to obtain the Group V metal precursor.

7. The preparation method according to claim 6, characterized in that: The specific operation of the reaction is: M(NR0)L(NR2)2 and a solvent are mixed and cooled to below 0°C, and a ligand HOCR1R2(CR3R4) is added thereto. X NR5R6 reaction to obtain the Group V metal precursor.

8. The preparation method according to claim 7, characterized in that: The solvent is selected from any one or a combination of at least two of n-hexane, n-pentane, toluene, xylene, trimethylbenzene, ether, tetrahydrofuran, ethylene glycol dimethyl ether or methyl tert-butyl ether; Preferably, the M(NR0)L(NR2)2 and the ligand HOCR1R2(CR3R4) X The molar ratio of NR5R6 is 1:2-10; Preferably, the reaction is carried out under the protection of a protective gas, and the protective gas is preferably nitrogen; Preferably, the reaction temperature is -30°C to 40°C, and the reaction time is 0.1-20h; Preferably, after the reaction is completed, low boiling substances are removed to obtain a crude product, and the crude product is purified to obtain a purified product; Preferably, the purification method comprises at least one of filtration, distillation, adsorption, crystallization, extraction or ion exchange.

9. A precursor composition, characterized in that The precursor composition comprises at least one Group V metal precursor according to any one of claims 1 to 5.

10. A method for depositing a thin film, characterized in that: The method comprises the following steps: depositing the Group V metal precursor described in any one of claims 1 to 5 onto the surface of a substrate to obtain a thin film.

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