Film deposition method and film deposition apparatus of boron nitride film

Abstract

To provide a film deposition method of a boron nitride film capable of depositing a hexagonal boron nitride film having good adhesion, good flatness, and good film quality, and a film deposition apparatus.SOLUTION: A film deposition method of a boron nitride film performs a plurality of times of sequences including the steps of: supplying a raw material gas containing a borazine-based compound and plasma to a substrate arranged in a chamber; and subsequently supplying plasma to the substrate without supplying the raw material gas. All or part of plurality of times sequences further include a step of supplying plasma of gas not containing hydrogen to the substrate after the step of supplying the plasma without supplying the raw material gas. In the step of supplying the raw material gas containing the borazine-based compound and the plasma and the step of supplying the plasma without supplying the raw material gas, plasma of gas containing hydrogen is used as the plasma.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for forming a boron nitride film.

Background Art

[0002] As a method for forming a boron nitride (BN) film, for example, those described in Patent Documents 1 to 3 are known.

[0003] Patent Document 1 describes a technique for forming a hexagonal BN (h-BN) film on the surface of a substrate by plasma CVD that generates a plasma of a boron-containing gas and a nitrogen gas and uses the plasma diffused from the plasma generation region. Patent Document 2 describes a method for forming a conformal BN film by a process including a CVD step in which at least a part of the deposition is performed without plasma using a boron-containing gas, and a step of exposing the deposited boron-containing film to a plasma containing N. Patent Document 3 describes a step of simultaneously performing a step of supplying a borazine-based gas containing a ligand to a substrate and a step of supplying a ligand-eliminating gas for eliminating the ligand from the substrate, intermittently under conditions where the borazine ring skeleton in the borazine-based gas is retained, to form a film having a borazine ring skeleton and containing boron and nitrogen on the substrate. Further, in Patent Document 3, NH3 gas is used as the ligand-eliminating gas, and a plasma of N2 gas, which is an inert gas, is used during film formation.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a method and an apparatus for forming a boron nitride film capable of forming a hexagonal boron nitride film having good adhesion and flatness and having good film quality.

Means for Solving the Problems

[0006] A method for forming a boron nitride film according to one aspect of the present disclosure includes a step of supplying a raw material gas containing a borazine compound and plasma to a substrate disposed in a chamber, and subsequently a step of supplying the plasma to the substrate without supplying the raw material gas. A sequence including these steps is performed a plurality of times, and all or part of the plurality of sequences further includes a step of supplying plasma of a gas not containing hydrogen to the substrate after the step of supplying the plasma without supplying the raw material gas. As the step of supplying the raw material gas containing the borazine compound and plasma, a step of supplying the raw material gas and plasma of a gas containing hydrogen to the substrate is performed, and as the step of supplying the plasma without supplying the raw material gas, a step of supplying plasma containing hydrogen without supplying the raw material gas is performed.

Advantages of the Invention

[0007] According to the present disclosure, there are provided a method and an apparatus for forming a boron nitride film capable of forming a hexagonal boron nitride film having good adhesion and flatness and having good film quality.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be specifically described with reference to the accompanying drawings.

[0010] <Background and Overview> First, the background and overview will be described. The BN film is an insulating film having excellent properties, and its application to various uses has been studied. In particular, the BN film has been attracting attention as a low dielectric constant insulating film (Low-k insulating film) that can achieve a k value of 3 or less. As the BN film, the hexagonal BN (h-BN) film having lateral orientation has good wet etching resistance and dry etching resistance.

[0011] Although Patent Document 1 mentioned above describes the formation of an h-BN film, the film formation method is CVD, and there is a possibility that the film formation property, adhesion, and film quality may not be sufficient. Further, Patent Document 2 describes that after performing a CVD step in which at least a part of the deposition is performed without plasma using a boron-containing gas, a conformal BN film can be obtained by treating with a plasma containing N, but it does not include the viewpoint of obtaining an h-BN film having good adhesion and flatness and good film quality. The film formation method described in Patent Document 3 focuses on the film formation rate of the BN film, and also does not include the viewpoint of obtaining an h-BN film having good adhesion and flatness and good film quality.

[0012] Therefore, in one embodiment of the present disclosure, on the premise that a sequence including a step of supplying a source gas containing a borazine compound and plasma to a substrate disposed in a chamber and subsequently a step of supplying plasma without supplying the source gas to the substrate is performed multiple times to form a BN film, the following requirements are added. That is, all or part of the plurality of sequences further includes a step of supplying a plasma of a gas not containing hydrogen after the step of supplying plasma without supplying the source gas to the substrate, and in the step of supplying the source gas and plasma and the subsequent step of supplying plasma, a plasma of a gas containing hydrogen is used as the plasma.

[0013] In this way, by using a plasma of a gas containing hydrogen as the plasma supplied together with the source gas containing a borazine compound and the plasma subsequently supplied without supplying the source gas, an h-BN film having good adhesion of the film to the substrate and flatness of the film surface can be obtained. Further, by supplying a plasma of a gas not containing hydrogen after the step of supplying plasma without supplying the source gas, hydrogen in the film can be removed to improve the film quality.

[0014] <Specific Embodiment> As described above, the method for forming a BN film according to this embodiment includes a step of supplying a raw material gas containing a borazine compound and plasma to a substrate while the substrate is disposed in a chamber of a film forming apparatus, and subsequently a step of supplying plasma to the substrate without supplying the raw material gas. A sequence including these steps is performed multiple times. Then, all or part of the multiple sequences further includes a step of performing a reforming treatment by supplying plasma of a gas not containing hydrogen to the substrate after the step of supplying plasma without supplying the raw material gas. In the above steps of supplying the raw material gas and plasma, and the step of supplying plasma without supplying the raw material gas, plasma of a gas containing hydrogen is used as the plasma.

[0015] FIG. 1 is a timing chart showing an example of a sequence of a method for forming a BN film according to an embodiment. The sequence in FIG. 1 consists of step ST1, step ST2, step ST3, step ST4, step ST5, and step ST6.

[0016] The substrate is not particularly limited, and may be, for example, a semiconductor substrate. As the semiconductor substrate, for example, one composed only of a substrate made of a semiconductor such as Si, or one having a desired film formed on a substrate made of a semiconductor can be used.

[0017] In step ST1, the inside of the chamber is purged by supplying a purge gas to the chamber in which the substrate is disposed. At this time, for the preparation of the flow of the raw material gas, the raw material gas may be flowed into the exhaust line or the filter tank may be filled with the raw material gas. The purge gas may be an inert gas, and noble gases such as Ar gas and He gas can be preferably used. Also, the plasma gas described later may be supplied simultaneously.

[0018] In step ST2, a plasma of a source gas containing a borazine-based compound and a gas containing hydrogen (H) is supplied to the substrate in the chamber. Thereby, the source gas is adsorbed onto the substrate, and the source gas is activated by the plasma to promote the adsorption. In FIG. 1, an example is shown in which NH3 gas is supplied as the gas containing H and is turned into plasma by high-frequency (RF) power.

[0019] The borazine-based compound used as the source gas is a compound based on borazine (B3H6N3) having a structure represented by the following formula (1). That is, the borazine-based compound is a compound having a borazine ring in which three Bs and three Ns that constitute borazine are alternately bonded as a basic skeleton, and for example, it may be an organic borazine compound in which some or all of the Hs of borazine are substituted with organic substituents. The organic borazine compound may be an alkyl borazine compound using an alkyl group as the organic substituent, and for example, trimethyl borazine (TMB) having a structure represented by the following formula (2) can be used. The source gas containing the borazine-based compound functions as a B source and an N source for the BN film.

[0020]

Chemical formula

[0021] The plasma of the gas containing H may be generated in the chamber when supplied to the substrate, or may be a remote plasma that introduces the plasma generated elsewhere into the chamber. The method for generating the plasma is not particularly limited, but capacitively coupled plasma obtained by applying high-frequency (RF) power to parallel plate electrodes to form a high-frequency electric field in the processing space where the substrate is disposed can be used. Other plasmas such as inductively coupled plasma and microwave plasma may also be used.

[0022] As the plasma of the gas containing H, it may be the plasma of a gas containing only H such as H2 gas, but a plasma of a gas containing H and N, for example, a plasma of ammonia (NH3) gas (also referred to as NH3 plasma) may be used. Further, it may be a plasma of a gas containing NH3 gas (for example, NH3 + N2 gas). When using a plasma of a gas containing H and N, N in the plasma also functions as an N source for the BN film. The plasma is preferably an energy such that the basic skeleton of the source gas is not destroyed when forming the h-BN film.

[0023] In step ST3, after step ST2, the supply of the source gas is stopped and only the plasma containing H is supplied. Thereby, the adsorption of the source gas is promoted, and the reaction of the source gas adsorbed on the substrate to h-BN is promoted. Step ST3 is continuously performed after step ST2. The plasma containing H at this time uses the same plasma as in step ST2.

[0024] By using a plasma of a gas containing H, for example, a plasma containing NH3, as the plasma in step ST2 and step ST3, an h-BN film is formed, and by containing H groups or NHx groups in the film, discontinuous portions occur in the borazine ring structure of h-BN in the plane of the film, and the stress difference from the substrate is relaxed, so that the adhesion between the BN film and the substrate and the flatness of the surface of the BN film become good.

[0025] In steps ST2 and ST3, the temperature may be 200 to 400 °C. The lower the temperature, the more difficult it is to form h-BN. Also, the pressure may be 4 Torr or more. However, when the pressure is 12 Torr or more, the film growth rate (GPC: Growth per Cycle) tends to be too low. Also, the time (film formation time) of step ST2 may be 2 seconds or less. When it exceeds 2 seconds, the amorphous BN component tends to increase. The time (plasma time) of step ST3 may be 4 seconds or more. When it is 4 seconds or more, the formation of the lateral orientation of h-BN tends to be promoted. The RF power of the plasma in steps ST2 and ST3 may be 100 W or more. The lower the power, the more the film quality tends to deteriorate.

[0026] In step ST4, a purge gas is supplied into the chamber to purge the gas remaining in the chamber after step ST3. The purge gas may be an inert gas, and noble gases such as Ar gas and He gas can be preferably used. In step ST4, as shown in FIG. 1, a gas containing no H (for example, N2 gas) to be used in step ST5 described later may be supplied.

[0027] In step ST5, a plasma of a gas containing no H is supplied to the substrate for modification treatment. The plasma of the gas containing no H may be generated in the chamber or may be a remote plasma that introduces the plasma generated at another location into the chamber, as long as it is supplied to the substrate, similar to the H-containing plasma in steps ST2 and ST3. The plasma generation method is not particularly limited either, and capacitively coupled plasma, inductively coupled plasma, microwave plasma, etc. can be used, similar to the plasma of the H-containing gas. The plasma of the gas containing no H may be, for example, a plasma of N2 gas (also referred to as N2 plasma) or a plasma of a noble gas such as Ar gas. Also, a plasma containing both N2 gas and a noble gas may be used. By the modification treatment with the plasma containing no H in step ST5, the film quality of the BN film can be improved through reduction of H in the film and the like.

[0028] In step ST5, the temperature may be 200 to 400 °C, similar to steps ST2 and ST3. Also, the pressure may be 6 Torr or more. Further, the time of step ST5 (reforming treatment time) may be 1 sec or more. The RF power of the plasma in step ST5 may be 400 W or more.

[0029] In step ST6, a purge gas is supplied into the chamber to purge the gas remaining in the chamber after step ST5. The purge gas may be an inert gas, and noble gases such as Ar gas and He gas can be preferably used.

[0030] By the sequence of steps ST1 to ST6 as described above, a thin unit film of h-BN is formed. Then, by performing a plurality of sequences including the sequence of steps ST1 to ST6, an h-BN film with a desired film thickness is formed.

[0031] Note that instead of the sequence of steps ST1 to ST6, as shown in FIG. 2, a sequence in which a pre-plasma step (step ST7) of performing plasma treatment on the substrate prior to step ST2 may be added. This step ST7 is for making the surface smoothness of the formed BN film better. The pre-plasma step of step ST7 can be performed in the same manner as step ST3.

[0032] Also, as shown in FIG. 3, instead of step ST1, a sequence in which a pre-flow step (step ST8) of supplying a borazine-based compound gas to the substrate prior to step ST2 may be performed. The pre-flow step of step ST8 is performed by supplying the same borazine-based compound gas as in step ST2 without using plasma. This pre-flow step of step ST8 is for increasing the step coverage of the formed BN film. In step ST8, a purge gas such as a noble gas may be supplied together with the borazine-based compound gas. Further, a plasma gas may also be supplied.

[0033] In this embodiment, in any of the sequences of FIGS. 1 to 3, it includes a step ST2 of supplying a raw material gas and a plasma containing H, a subsequent step ST3 of supplying only the plasma containing H, and a step ST5 of supplying a plasma not containing H to perform a reforming treatment. By steps ST2 and ST3, an h-BN film with good film adhesion and flatness can be formed. However, since the film quality deteriorates due to the inclusion of H in the film, in step ST5, a reforming treatment is performed with a plasma of a gas not containing H to improve the film quality.

[0034] The following will be described in detail. In this embodiment, by supplying a raw material gas containing a borazine-based compound to the substrate, the borazine-based compound is adsorbed on the substrate, the ligand is removed while maintaining the borazine skeleton of the borazine-based compound, and a two-dimensional h-BN film can be formed. At this time, by supplying plasma in addition to the raw material gas, the borazine-based compound is activated, and the adsorption and reaction of the raw material gas are promoted. Further, the reaction is promoted by the subsequent supply of only plasma. Therefore, an h-BN film can be formed at a high film formation rate (GPC).

[0035] At this time, by using a gas containing H as the gas for generating plasma, due to the plasma of the gas containing H, by including an H group or an NHx group in the film, a discontinuous portion occurs in the borazine ring structure of h-BN in the plane of the film, and the stress difference from the substrate is relaxed. Compared with the case of using a gas not containing H as the gas for generating plasma, the film adhesion to the substrate and the flatness of the film surface are improved. At this time, as the plasma of the gas containing H, by using a gas containing H and N, such as NH3 gas, N in the plasma also functions as an N source for the BN film, and the film adhesion and the flatness of the film surface can be made better.

[0036] However, it was found that the inclusion of H in the plasma in steps ST2 and ST3 increases the amount of H in the film, which in turn increases the B / N ratio of the BN film and causes problems with film quality, such as a decrease in oxidation resistance.

[0037] In contrast, it has been found that by supplying plasma of a gas not containing H in step ST5 to perform the modification process, H and H-containing groups are released from the borazine-based compound in the gas phase and in the film, the film is modified, the amount of H in the film is reduced, the film quality is improved, and the lateral orientation is also improved.

[0038] The mechanism of film modification at this time will be described with reference to FIG. Here, an example will be described in which TMB is used as the borazine-based compound in step ST2, NH3 plasma is used as the plasma of the gas containing H in steps ST2 and ST3, and N2 plasma is used as the plasma of the gas not containing H in step ST5.

[0039] First, in step ST3, NH3 plasma is supplied to the TMB in the gas phase and in the film of the structure (a) generated in step ST2, and NHx in the plasma is * Or H * By the action of the above, CH3 and H are released from the TMB in the gas phase and the film, resulting in the structure shown in (b). Then, in step ST5, N2 plasma is supplied to the structure shown in (b), and the N * As a result of this action, H and NHx are eliminated from the structure shown in (b) or replaced by N:, resulting in the structure shown in (c). The structure shown in (c) has adsorption sites for TMB, and the adsorption of TMB is promoted by the supply of TMB in the next step. This reduces the H in the BN film, improving the film quality. The lateral orientation is also improved. Specifically, the film quality is improved in terms of oxidation resistance, a BN ratio close to the stoichiometric composition is achieved, the k value and leakage current are reduced, and the film density is increased.

[0040] The experiments that confirmed this will be described below. Here, as shown in Fig. 5(a), a sample 1 was prepared by repeatedly depositing a BN film on a substrate by repeating the sequence of TMB + N2 plasma (TMB + pN2), N2 plasma (pN2), and purge (PRG) multiple times. Also, as shown in Fig. 5(b), a sample 2 was prepared by repeatedly depositing a BN film on a substrate by repeating the sequence of TMB + NH3 plasma (TMB + pNH3), NH3 plasma (pNH3), and purge (PRG) multiple times. Further, as shown in Fig. 5(c), samples 3 to 5 were prepared by repeatedly depositing a BN film on a substrate by repeating the sequence of TMB + NH3 plasma (TMB + pNH3), NH3 plasma (pNH3), purge (PRG), N2 plasma modification (pN2), and purge (PRG) multiple times. Samples 3 to 5 had the modification time of N2 plasma varied. Specifically, it was 1 sec for sample 3, 4 sec for sample 4, and 16 sec for sample 5. As other conditions, the temperature was 400 °C, the pressure was 8 Torr, the time for TMB + pN2 and TMB + pNH3 was 2 sec, and the time for pN2 and pNH3 was 4 sec (16 sec only for sample 5).

[0041] Fig. 6 is a diagram showing the absorbance in the wavenumber region including the peak of h-BN (1380 cm -1 ) measured by FT-IR for samples 1 to 5. As shown in Fig. 6, the peak of h-BN can be seen in samples 1 and 2 as well, but an increase in the h-BN peak is observed due to N2 plasma modification, and the degree of increase in the h-BN peak becomes larger as the N2 plasma modification time is prolonged. That is, it was confirmed that the lateral orientation of h-BN was improved by N2 plasma modification.

[0042] Fig. 7 is a diagram showing the peak of NHx (3300 - 3500 cm -1) is a diagram showing the absorbance in the wavenumber region including. As shown in Fig. 7, for Sample 2 using NH3 plasma during film formation, the peak of NHx is higher than that of Sample 1 using N2 plasma, indicating that the amount of H in the film is larger. In contrast, for Samples 3 - 5 with N2 plasma modification after NH3 plasma, the peak of NHx is lower than that of Sample 2, and it can be seen that the peak of NHx further decreases as the modification time is prolonged. From this, it was confirmed that H in the film is reduced by N2 plasma modification.

[0043] Fig. 8 is a diagram showing the absorbance in the wavenumber region including the peak of BOH (around 3200 cm -1 ) measured by FT - IR for Samples 1 - 5. As shown in Fig. 8, the peak of BOH can be seen in Sample 2 using NH3 plasma during film formation, while the peak of BOH is hardly seen in Sample 1 using N2 plasma. That is, in Sample 2, it is considered that BOH derived from atmospheric oxidation is formed due to the presence of NH3. In contrast, for Samples 3 - 5 with N2 plasma modification after NH3 plasma, BOH is reduced compared to Sample 2.

[0044] Fig. 9 is a diagram showing the film composition and B / N ratio of the BN films of Samples 1 - 5. For the BN film, impurities such as oxygen are less, and the closer the B / N ratio is to 1, the more preferable it is. However, as shown in Fig. 9, in Sample 2 using NH3 plasma, the amount of oxygen is as much as 5 at%, and the B / N ratio is also as large as 1.15, being B - rich. This is considered to be because BOH is generated in Sample 2, thereby breaking the bond of the BN ring and causing N to desorb. In contrast, for Samples 3 - 5 with N2 plasma modification after NH3 plasma, the amount of oxygen decreases, and the B / N ratio is improved to 1.06 - 1.09. In particular, regarding the amount of oxygen, in Sample 5 with 16 - sec N2 plasma modification, it has decreased to 1 at%.

[0045] From the results of FIGS. 8 and 9, in Sample 2 using NH3 plasma, the generation of BOH was observed and the oxidation resistance was not sufficient. Therefore, the oxygen in the film was high and the B / N ratio was also high. However, by performing N2 plasma modification, it was confirmed that the oxidation resistance was improved, the amount of oxygen in the film was reduced, and the B / N ratio also became good.

[0046] FIG. 10 is a diagram showing the k value and leakage current of Samples 1 to 5. As shown in this figure, in Sample 2 using NH3 plasma, the k value was 3.0, higher than that of Sample 1, and the leakage current value was 4.7E-08 A / cm 2 which was about the same as that of Sample 1. On the other hand, in Sample 4 where N2 plasma modification was performed after NH3 plasma, the k value was 2.6 and the leakage current value was 2.4E-08 A / cm 2 both of which were decreased.

[0047] FIG. 11 is a diagram showing the relationship between the N2 plasma modification time after NH3 plasma and the film density. The value when the N2 plasma modification time is 0 sec is the value of Sample 2 without N2 plasma modification. As shown in FIG. 11, when no N2 plasma modification was performed, the film density was 1.85 g / cm 3 but by performing N2 plasma modification for 4 sec, the film density increased to 2.15 g / cm 3 up to.

[0048] From the results of FIGS. 9 to 11, after film formation using NH3 plasma, by performing N2 plasma modification, the k value and the leakage current value decreased, and the film density increased. It was confirmed that N2 plasma modification has an effect of improving the film quality.

[0049] In addition, all sequences may include a step ST2 of supplying a raw material gas and a plasma containing H, a step ST3 of subsequently supplying only the plasma containing H, and a step ST5 of supplying a plasma not containing H to perform a reforming treatment, as shown in the sequences of FIGS. 1 to 3, or some sequences may consist of these steps. In this case, other sequences may include a step of supplying a raw material gas containing a borazine compound and a plasma to at least a substrate, and a step of subsequently supplying a plasma without supplying the raw material gas to the substrate.

[0050] For example, the reforming treatment with the plasma not containing H in step ST5 does not necessarily need to be performed for all sequences in which steps ST2 and ST3 are carried out. That is, for example, it may be performed periodically, such as once every predetermined number of times (for example, 2 to 10 times) of the sequences in which steps ST2 and ST3 are carried out.

[0051] Also, a part of a plurality of sequences may be replaced with a plasma not containing H, such as N2 plasma, instead of the plasma containing H in steps ST2 and ST3, such as NH3 plasma. Plasma reforming treatment may not be required in this sequence. For example, the initial film formation stage where particularly high adhesion and flatness are required may be carried out in the sequence of FIG. 1 (or the sequence of FIG. 2, the sequence of FIG. 3), and the bulk film formation stage may be carried out in a sequence using a plasma not containing H (for example, N2 plasma). At this time, for example, instead of replacing all with N2 plasma in the bulk film formation stage after the sequence using NH3 plasma in the initial film formation stage, a transition period consisting of a plurality of sequences may be provided between them, and the frequency of N2 plasma relative to NH3 plasma may be gradually increased from the initial film formation stage to the bulk film formation stage. Also, in the transition period, a part of the NH3 gas as the plasma gas may be replaced with N2 gas, and the ratio of N2 gas may be gradually increased from the initial film formation stage to the bulk film formation stage so as to transition to N2 plasma.

[0052] <Film forming apparatus> Next, an example of a film forming apparatus applicable to the implementation of the above BN film forming method will be described.

[0053] FIG. 12 is a cross-sectional view showing an example of a film forming apparatus. The film forming apparatus 100 includes a chamber 1, a mounting table 2, a shower head 3, an exhaust unit 4, a gas supply mechanism 5, a plasma generation unit 6, and a control unit 7, and forms a BN film on a substrate W. The substrate W is not particularly limited, and may be, for example, a semiconductor substrate such as an Si substrate.

[0054] The chamber 1 is made of a metal such as aluminum and has a substantially cylindrical shape. An inlet / outlet 11 for loading and unloading the substrate W is formed in the side wall of the chamber 1, and the inlet / outlet 11 can be opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross-section is provided on the main body of the chamber 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed in the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the chamber 1. The space between the ceiling wall 14 and the exhaust duct 13 is hermetically sealed by a seal ring 15.

[0055] The mounting table 2 is for mounting the substrate W in a horizontal state, has a disk shape corresponding to the size of the substrate W, and is supported by a support member 23. The mounting table 2 is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as aluminum or a nickel-based alloy, and a heater 21 for heating the substrate W is embedded therein. A cover member 22 is provided on the mounting table 2 so as to cover the side surface.

[0056] The support member 23 that supports the mounting table 2 extends downward from the center of the bottom surface of the mounting table 2 through a hole formed in the bottom wall of the chamber 1 and reaches below the chamber 1. The lower end thereof is connected to the mounting table lifting mechanism 24. The mounting table 2 can be lifted and lowered by the mounting table lifting mechanism 24 via the support member 23 between the processing position shown by the solid line and the transfer position below it where the substrate can be transferred, shown by the one-dot chain line. Further, a flange portion 25 is attached to the position below the chamber 1 of the support member 23, and a bellows 26 is provided between the bottom surface of the chamber 1 and the flange portion 25 to partition the atmosphere inside the chamber 1 from the outside air and expand and contract as the mounting table 2 moves up and down.

[0057] Near the bottom surface of the chamber 1, three (only two are shown in the figure) substrate support pins 27 protrude upward from the lifting plate 27a. The substrate support pins 27 can be lifted and lowered via the lifting plate 27a by a substrate support pin lifting mechanism 28 provided below the chamber 1, and are inserted into through holes 2a provided in the mounting table 2 at the transfer position and can protrude and retract with respect to the upper surface of the mounting table 2. By lifting and lowering the substrate support pins 27 in this way, the substrate W is transferred between a substrate transfer mechanism (not shown) and the mounting table 2. A bellows 28a is provided between the bottom surface of the chamber 1 and the substrate support pin lifting mechanism 28.

[0058] The shower head 3 supplies the processing gas in a shower shape into the chamber 1. The shower head 3 is provided so as to face the mounting table 2 and has substantially the same diameter as the mounting table 2. The shower head 3 has a shower main body portion 31 fixed to the ceiling wall 14 of the chamber 1 and a shower plate 32 connected below the shower main body portion 31. A gas diffusion space 33 is formed between the shower main body portion 31 and the shower plate 32, and a gas introduction hole 36 provided so as to penetrate the center of the main body portion 31 and the ceiling wall 14 of the chamber 1 is connected to this gas diffusion space 33. Gas discharge holes 34 are formed in the shower plate 32. When the mounting table 2 is in the processing position, a processing space S is formed between the shower plate 32 and the mounting table 2.

[0059] The exhaust section 4 includes an exhaust pipe 41 connected to the exhaust port 13b of the exhaust duct 13, an automatic pressure control (APC) valve 42 connected to the exhaust pipe 41, and an exhaust mechanism 43 having a vacuum pump. During the process, the gas in the chamber 1 reaches the exhaust duct 13 through the slit 13a and is exhausted from the exhaust duct 13 through the exhaust pipe 41 by the exhaust mechanism 43 of the exhaust section 4.

[0060] The gas supply mechanism 5 supplies the gas used for film formation to the shower head 3, and supplies a source gas containing a borazine compound, a plasma gas containing H, a plasma gas for reforming treatment not containing H, and a purge gas. As described above, here, TMB is used as the borazine compound, NH3 gas is used as the plasma gas containing H, N2 gas is used as the plasma gas for reforming treatment not containing H, and Ar gas is used as the purge gas. However, as described above, the borazine compound, the plasma gas containing H, the plasma gas for reforming treatment not containing H, and the purge gas are not limited to these.

[0061] The gas supply mechanism 5 has a TMB gas supply source 51 that supplies TMB gas as the source gas, an NH3 gas supply source 52 that supplies NH3 gas as the gas containing H that generates plasma for film formation, and an N2 gas supply source 53 that supplies N2 gas as the gas not containing H that generates plasma for reforming. It also has a first Ar gas supply source 54, a second Ar gas supply source 55, and a third Ar gas supply source 56 that supply Ar gas as the purge gas.

[0062] One end of the TMB gas line 57 is connected to the TMB gas supply source 51. A valve 57a, a filter tank 57b, and a flow rate adjustment unit 57c are installed in the TMB gas line 57 in order from the downstream side. One end of the NH3 gas line 58 is connected to the NH3 gas supply source 52. A valve 58a, a filter tank 58b, and a flow rate adjustment unit 58c are installed in the NH3 gas line 58 in order from the downstream side. One end of the N2 gas line 59 is connected to the N2 gas supply source 53. A valve 59a, a filter tank 59b, and a flow rate adjustment unit 59c are installed in the N2 gas line 59 in order from the downstream side. The TMB gas line 57, the NH3 gas line 58, and the N2 gas line 59 are connected to one end of a common line 63, and the other end of the common line 63 is connected to the gas introduction hole 36 of the shower head 3.

[0063] One end of the first Ar gas line 60 is connected to the first Ar gas supply source 54. A valve 60a and a flow rate adjustment unit 60c are installed in the first Ar gas line 60 in order from the downstream side. The other end of the first Ar gas line 60 is connected to a position downstream of the valve 57a in the TMB gas line 57. One end of the second Ar gas line 61 is connected to the second Ar gas supply source 55. A valve 61a and a flow rate adjustment unit 61c are installed in the second Ar gas line 61 in order from the downstream side. The other end of the second Ar gas line 61 is connected to a position downstream of the valve 58a in the NH3 gas line 58. One end of the third Ar gas line 62 is connected to the third Ar gas supply source 56. A valve 62a and a flow rate adjustment unit 62c are installed in the third Ar gas line 62 in order from the downstream side. The other end of the third Ar gas line 62 is connected to a position downstream of the valve 59a in the N2 gas line 59. During the film formation process, the valves 60a, 61a, and 62a are always open, and Ar gas as a purge gas is constantly supplied into the chamber 1 from the first Ar gas line 60, the second Ar gas line 61, and the third gas line 62 through the TMB gas line 57, the NH3 gas line 58, and the N2 gas line 59.

[0064] Valves 57a, 58a, and 59a are configured as high-speed on-off valves that rapidly open and close the corresponding gas lines. Valves 60a, 61a, and 62a may be ordinary on-off valves.

[0065] Filter tanks 57b, 58b, and 59b each temporarily store TMB gas, NH3 gas, and N2 gas, respectively, before supplying them into chamber 1. By storing gas in filter tanks 57b, 58b, and 59b, the pressure inside them is increased to a predetermined pressure, and then by opening valves 57a, 58a, and 59a, each gas can be discharged into chamber 1. As a result, a large flow rate of gas can be stably supplied to chamber 1.

[0066] Flow rate adjustment units 57c, 58c, 59c, 60c, 61c, and 62c are constituted by, for example, mass flow controllers, and adjust and control the flow rate of the gas flowing through the corresponding gas lines.

[0067] Plasma generation unit 6 includes a power supply line 65 connected to the shower main body 31 of shower head 3, and a matching unit 66 and a radio frequency (RF) power supply 67 connected to power supply line 65. By supplying RF power from this RF power supply 67 to shower head 3, an RF electric field is formed in the processing space S between shower head 3 and mounting table 2, and capacitive coupling plasma is generated by this RF electric field. When mounting table 2 is formed of a ceramic material, an electrode is embedded in mounting table 2, and an RF electric field is formed between shower head 3 and the electrode.

[0068] The control unit 7 is composed of a computer and includes a main control unit equipped with a CPU, an input device, an output device, a display device, and a storage device (storage medium). The main control unit controls components of the film forming apparatus 100, such as valves, flow rate adjustment units, automatic pressure control valves, heaters, lifting mechanisms, etc. The storage device stores parameters of various processes executed in the film forming apparatus 100. Further, the storage device has a storage medium storing a program for controlling the processes executed in the film forming apparatus 100, that is, a process recipe. The main control unit calls a predetermined process recipe stored in the storage medium and causes the film forming apparatus 100 to execute a predetermined operation based on the process recipe.

[0069] In the film forming apparatus 100 configured as described above, first, the gate valve 12 is opened, and the substrate W is carried into the chamber 1 through the carry-in / outlet 11 by a transfer device (not shown) and placed on the mounting table 2. The transfer device is retracted, and the mounting table 2 is raised to the processing position. Then, the gate valve 12 is closed, the inside of the chamber 1 is evacuated, and the temperature of the mounting table 2 (substrate temperature) is heated and controlled to a desired temperature by the heater 21.

[0070] In this state, the actual film forming process is started. When performing the sequence shown in FIG. 1 described above, first, Ar gas is supplied as a purge gas from the first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 56 to the processing space S through the first Ar gas line 60, the second Ar gas line 61, the third Ar gas line 62, and the shower head 3 to purge the inside of the chamber 1 in step ST1 (step ST1). At this time, NH3 gas, which is a plasma gas, may be supplied. Also, the raw material gas TMB gas may be filled in the filter tank or flowed through the exhaust line to prepare for supply.

[0071] Next, TMB gas and NH3 plasma are supplied to the substrate W (step ST2). Specifically, while supplying Ar gas, with NH3 gas being supplied from the NH3 gas supply source 52 through the NH3 gas line 58 and the shower head 3 as plasma gas to the processing space S, RF power is supplied from the RF power supply 67 of the plasma generation unit 6 to the shower head 3. Thereby, NH3 plasma is generated in the processing space S. Further, TMB gas, which is a source gas, is supplied from the TMB gas supply source 51 through the TMB gas line 57 and the shower head 3 to the processing space S. As a result, TMB gas and NH3 plasma are supplied to the substrate W, the TMB gas is adsorbed on the substrate W, and the TMB gas in the gas phase and in the film is activated by the NH3 plasma, promoting its adsorption.

[0072] After step ST2 ends, with the generation of NH3 plasma continued, the valve 57a is closed to stop the TMB gas, and only NH3 plasma is supplied to the substrate W (step ST3). By further activating the TMB gas in the film in this way, the adsorption of the TMB gas is promoted, and the reaction of the TMB gas with h-BN is also promoted.

[0073] Next, the RF power from the RF power supply 67 is turned OFF, the valve 58a is closed to stop the supply of NH3 gas, and while Ar gas is being supplied, the inside of the chamber 1 is purged (step ST4). At this time, the valve 59a may be opened, and N2 gas may also be supplied as plasma gas for reforming treatment from the N2 gas supply source 53 through the N2 gas line 59 and the shower head 3 to the processing space S.

[0074] Next, the RF power from the RF power supply 67 is turned ON, and by continuing the supply of N2 gas, N2 plasma is generated in the processing space S, and reforming treatment with the N2 plasma is performed (step ST5).

[0075] Next, the RF power from the RF power supply 67 is turned OFF, the valve 59a is closed to stop the supply of N2 gas, and while Ar gas is being supplied, the inside of the chamber 1 is purged (step ST6).

[0076] By repeating the sequence of steps ST1 to ST6 as described above for a desired number of cycles, an h-BN film with a desired film thickness is formed.

[0077] In addition, as shown in FIG. 2, when a prep plasma step (step ST7) is performed prior to step ST2, step ST7 can be performed in the same manner as step ST3. Further, as shown in FIG. 3, when a preflow step (step ST8) is performed instead of step ST1, it is performed by supplying a borazine-based compound gas similar to that in step ST2 without using plasma.

[0078] Also, as described above, it is not necessary to have multiple sequences of steps ST1 to ST6 (or the sequences in FIGS. 2 and 3), and sequences that do not perform the modification treatment with N2 plasma may be partially included. Further, sequences that perform the plasma during film formation and the subsequent plasma with N2 plasma may be partially included.

[0079] Thus, in the steps of supplying TMB gas and plasma, and the steps of supplying plasma without supplying TMB gas, since NH3 plasma is used as the plasma, the adhesion of the formed h-BN film and the flatness of the film surface are improved. Further, by the subsequent modification treatment with N2 plasma, H in the film is reduced, and an h-BN film with good film quality is obtained.

[0080] <Other applications> As described above, the embodiments have been described. However, the embodiments disclosed this time should be considered to be illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims.

[0081] For example, in the above-described embodiment, as the basic sequence, the supply of a borazine-based compound gas and a plasma containing H (step ST2), the supply of a plasma containing H (step ST3), purging (step ST4), the reforming treatment with a plasma not containing H (step ST5), and purging (step ST6) shown in FIGS. 1 to 3 are exemplified. However, as the basic sequence, as long as it includes the step of supplying a plasma containing a borazine-based compound gas and H to the substrate, the subsequent step of supplying a plasma containing H to the substrate, and the reforming treatment with a plasma not containing H, it is not limited to these. Also, as described above, not only when all of the plurality of sequences are the above basic sequence, but as long as the step of supplying a raw material gas containing a borazine-based compound gas and a plasma to the substrate and the step of supplying a plasma to the substrate without supplying the raw material gas subsequently are included, some of the sequences may be different from the basic sequence.

[0082] Also, the film forming apparatus shown in FIG. 12 is merely an example, and the apparatus is not particularly limited as long as it can sequentially perform step ST2 of supplying a plasma containing a borazine-based compound gas and H to the substrate, step ST3 of supplying a plasma containing H, and step ST5 which is the reforming treatment with a plasma not containing H, and it may be a batch type as well as a single wafer type. Further, in the film forming apparatus 100 of FIG. 12, an example of supplying RF power to the shower head 3 to generate a capacitively coupled plasma between the shower head 3 and the mounting table 2 is shown, but it is not limited to this, and various plasmas such as inductively coupled plasma and microwave plasma can be used. Furthermore, it may be a remote plasma that transports the plasma generated at another location to the substrate.

Description of Reference Numerals

[0083] 1; Chamber 2; Mounting Table 3; Shower Head 4; Exhaust Section 5; Gas Supply Mechanism 6; Plasma Generation Unit 7; Control Unit 51; TMB Gas Supply Source 52; NH3 Gas Supply Source 53; N2 Gas Supply Source 54, 55, 56; Ar Gas Supply Source 100; Film Deposition Apparatus W; Substrate

Claims

1. A step of supplying a source gas containing a borazine compound and plasma to a substrate disposed in a chamber, and subsequently a step of supplying the plasma to the substrate without supplying the source gas are performed a plurality of times. All or part of the plurality of sequences further includes a step of supplying plasma of a gas not containing hydrogen to the substrate after the step of supplying the plasma without supplying the source gas. As the step of supplying the source gas containing the borazine compound and plasma, a step of supplying the source gas and plasma of a gas containing hydrogen to the substrate is performed. As the step of supplying the plasma without supplying the source gas, a step of supplying plasma containing hydrogen without supplying the source gas is performed. A method for forming a boron nitride film.

2. The sequence includes a step of purging the inside of the chamber, then a step of supplying the source gas and plasma of a gas containing hydrogen to the substrate, subsequently a step of supplying plasma containing hydrogen without supplying the source gas to the substrate, then a step of purging the inside of the chamber, then a step of supplying plasma of a gas not containing hydrogen to the substrate, and a step of purging the inside of the chamber. The method for forming a boron nitride film according to claim 1.

3. The sequence includes a step of purging the inside of the chamber, then a step of supplying plasma containing hydrogen to the substrate, then a step of supplying the source gas and plasma containing hydrogen to the substrate, subsequently a step of supplying plasma containing hydrogen without supplying the source gas to the substrate, then a step of purging the inside of the chamber, then a step of supplying plasma of a gas not containing hydrogen to the substrate, and then a step of purging the inside of the chamber. The method for forming a boron nitride film according to claim 1.

4. The sequence includes a step of supplying the source gas to the substrate, then a step of supplying the plasma containing the source gas and hydrogen to the substrate, subsequently a step of supplying the plasma containing hydrogen without supplying the source gas to the substrate, then a step of purging the inside of the chamber, then a step of supplying the plasma of the gas not containing hydrogen to the substrate, and then a step of purging the inside of the chamber, which is the method for forming a boron nitride film according to claim 1.

5. The borazine compound is an alkyl borazine compound, which is the method for forming a boron nitride film according to any one of claims 1 to 4.

6. The borazine compound is trimethyl borazine, which is the method for forming a boron nitride film according to claim 5.

7. The gas containing hydrogen contains hydrogen and nitrogen, which is the method for forming a boron nitride film according to any one of claims 1 to 4.

8. The gas containing hydrogen is ammonia gas, which is the method for forming a boron nitride film according to claim 7.

9. The gas not containing hydrogen is at least one of nitrogen gas and rare gas, which is the method for forming a boron nitride film according to any one of claims 1 to 4.

10. As a part of the plurality of sequences, a sequence including a step of supplying the plasma of the source gas and the gas containing hydrogen to the substrate, a step of supplying the plasma containing hydrogen without supplying the source gas, and a step of supplying the plasma of the gas not containing hydrogen to the substrate is carried out. As other parts of the plurality of sequences, a step of supplying a plasma of the raw material gas and a gas containing hydrogen to the substrate, and a step of supplying a plasma containing hydrogen without supplying the raw material gas are included, and a sequence not including a step of supplying a plasma of a gas not containing hydrogen to the substrate is performed. The method for forming a boron nitride film according to any one of claims 1 to 4.

11. The method for forming a boron nitride film according to claim 10, wherein a step of periodically supplying a plasma of a gas not containing hydrogen to the substrate is performed.

12. As a part of the plurality of sequences, a step of supplying a plasma of the raw material gas and a gas containing hydrogen to the substrate, a step of supplying a plasma containing hydrogen without supplying the raw material gas, and a step of supplying a plasma of a gas not containing hydrogen to the substrate are included, and As other parts of the plurality of sequences, a step of supplying a plasma of the raw material gas and a gas not containing hydrogen to the substrate, and subsequently a step of supplying a plasma of a gas not containing hydrogen without supplying the raw material gas to the substrate are included. The method for forming a boron nitride film according to any one of claims 1 to 4.

13. In the initial stage of film formation, a step of supplying a plasma of the raw material gas and a gas containing hydrogen to the substrate, a step of supplying a plasma containing hydrogen without supplying the raw material gas, and a step of supplying a plasma of a gas not containing hydrogen to the substrate are included, and In the bulk film formation stage, a step of supplying a plasma of the raw material gas and a gas not containing hydrogen to the substrate, and subsequently a step of supplying a plasma of a gas not containing hydrogen without supplying the raw material gas to the substrate are included. The method for forming a boron nitride film according to claim 12.

14. 14. The method for forming a boron nitride film according to claim 13, further comprising the steps of: providing a transition period between the initial film-forming stage and the bulk film-forming stage, the transition period consisting of a plurality of sequences; and gradually increasing a frequency of plasma of the hydrogen-free gas from the initial film-forming stage to the bulk film-forming stage, or replacing a portion of the hydrogen-containing gas with the hydrogen-free gas, thereby increasing a ratio of the hydrogen-free gas from the initial film-forming stage to the bulk film-forming stage.

15. a chamber in which the substrate is accommodated; a gas supply mechanism for supplying a raw material gas containing a borazine-based compound and a gas for generating plasma into the chamber; an exhaust mechanism for exhausting the inside of the processing vessel; a plasma generating unit for generating plasma; A heating mechanism for heating the substrate; A control unit; having The control unit is a step of supplying a raw material gas containing a borazine-based compound and plasma to a substrate placed in the chamber, and a step of subsequently supplying the plasma to the substrate without supplying the raw material gas, the step of repeatedly performing a sequence including the steps of: The boron nitride film forming apparatus, wherein all or a part of the multiple sequences further includes a step of supplying plasma of a gas not containing hydrogen to the substrate after the step of supplying the plasma without supplying the raw material gas, wherein a step of supplying the raw material gas and the plasma of the gas containing hydrogen to the substrate is carried out as a step of supplying the raw material gas and plasma containing the borazine-based compound, and a step of supplying the plasma without supplying the raw material gas is carried out as a step of supplying the plasma without supplying the raw material gas.

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