Boron nitride film formation method and formation device

Abstract

To provide a film formation technology that improves step coverage property of a boron nitride film.SOLUTION: Disclosed is a boron nitride film formation method including (a) a step for executing a sequence. The sequence includes: (a1) a step for supplying a first processing gas containing a first borazine compound and plasma chemical species to a substrate disposed in a chamber of a film formation device, in order to form a boron nitride film on the substrate; and (a2) a step for supplying plasma chemical species to the substrate without supplying the first processing gas to the substrate. The film formation method further includes (b) a step for supplying a second processing gas that contains a second borazine compound containing an alkyl group to the substrate without supplying plasma chemical species to the substrate. The film formation method further includes a step for repeating a cycle including (a) and (b).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to a method and apparatus for forming a boron nitride film.

Background Art

[0002] Patent Document 1 describes a method of generating a plasma of a boron-containing gas and a nitrogen-containing gas in a plasma generation region and forming a hexagonal boron nitride film (BN film) on the surface of a substrate by plasma CVD (Chemical Vapor Deposition).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a film-forming technique for improving the step coverage of a boron nitride film.

Means for Solving the Problems

[0005] In one exemplary embodiment, a method for forming a boron nitride film is provided. The film-forming method includes a step of executing a sequence. The sequence includes: (a1) a step of supplying a first treatment gas containing a first borazine compound and plasma chemical species to a substrate to form a boron nitride film on the substrate disposed in a chamber of a film-forming apparatus; and (a2) a step of supplying plasma chemical species to the substrate without supplying the first treatment gas to the substrate. The film-forming method further includes: (b) a step of supplying a second treatment gas containing a second borazine compound containing an alkyl group to the substrate without supplying plasma chemical species to the substrate. The film-forming method further includes a step of repeating a cycle including (a) and (b).

Effects of the Invention

[0006] According to one exemplary embodiment, a film forming technique for improving the step coverage of a boron nitride film can be provided.

Brief Description of the Drawings

[0007]

Figure 1

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Figure 11

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Figure 13

Embodiments for Carrying Out the Invention

[0008] Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0009] <Method for Forming Boron Nitride Film> FIG. 1 is a timing chart showing a method for forming a boron nitride film (BN film) according to one exemplary embodiment. In FIG. 1, the states in which various gases are supplied and the state in which high-frequency (RF) power is supplied in a film formation method (hereinafter referred to as "method MT1") of one embodiment are shown by solid lines or dotted lines with arrows.

[0010] As shown in FIG. 1, in method MT1, cycle CY is repeated. In method MT1, cycle CY is performed y times. Here, y is an integer of 2 or more. Cycle CY is repeated with a substrate accommodated in the chamber of the film formation apparatus. The substrate may be, for example, a semiconductor substrate. The semiconductor substrate may include a semiconductor region containing a semiconductor material such as Si, or may be one in which a desired film and structure are formed on the semiconductor region.

[0011] Cycle CY includes sequence SQ1 and process ST3. In cycle CY, after sequence SQ1 is performed x times, process ST3 is performed. Here, x is an integer of 1 or more. In cycle CY, process ST3 may be a part of sequence SQ2. Sequence SQ2 may include process STc performed after process ST3.

[0012] Sequence SQ1 includes step ST1 and step ST2. The sequence SQ1 of method MT1 may further include step STa and step STb, or may include step STb but not step STa. Step STa is performed before step ST1. In step STa, the chamber is purged. In step STa, purge gas may be supplied into the chamber. The purge gas may be an inert gas. The inert gas may be a noble gas such as, for example, He gas.

[0013] In step STa, as shown by the dashed line with an arrow in FIG. 1, preparation of the flow of the first process gas may be performed. The first process gas is used in the subsequent step ST1. For the preparation of the flow of the first process gas, in step STa, the first process gas may be flowed into an exhaust line such as the exhaust line of the film forming apparatus 100 described later. Alternatively, in step STa, the first process gas may be filled into a tank such as the filter tank of the film forming apparatus 100.

[0014] Also, in step STa, plasma source gas may be supplied into the chamber. The plasma source gas is used to generate plasma therefrom in the subsequent step ST2. The plasma source gas is, for example, nitrogen (N2), hydrogen (H2), ammonia (NH3), or a noble gas (for example, argon (Ar)), but is not limited thereto.

[0015] In method MT1, after step STa, step ST1 is performed. In step ST1, the first process is performed. The first process includes supplying the first process gas and plasma species to the substrate. The first process gas includes a first borazine compound. In step ST1, a BN film is formed on the substrate by the first borazine compound. In step ST1, the adsorption of the first borazine compound may be promoted by the plasma species.

[0016] The first borazine compound and the second borazine compound used in step ST3 are compounds having a borazine ring containing three B (boron atoms) and three N (nitrogen atoms) bonded alternately as a basic skeleton. The first borazine compound may be the same as or different from the second borazine compound.

[0017] The first borazine compound may be borazine represented by the following formula (1), that is, cyclotriborazane (B3H6N3).

Chemical formula

[0018] The first borazine compound may be an organoborazine compound in which some or all of the H of borazine is substituted with an organic ligand. The organoborazine compound may be an alkylborazine compound containing an alkyl group as an organic ligand. The alkylborazine compound may be N,N’,N’’-trimethylborazine (TMB) having the structure represented by the following formula (2).

Chemical formula

[0019] The alkylborazine compound may contain TMB, N,N’,N’’-triethylborazine, N,N’,N’’-tripropylborazine, N,N’,N’’-triisopropylborazine, or B,B’,B’’-triethyl-N,N’,N’’-trimethylborazine, or one or more of these. The borazine compound contained in the first processing gas functions as a B source and an N source for the BN film formed on the substrate.

[0020] In step ST1, the plasma chemical species are supplied from the plasma generated from the plasma source gas to the substrate. The plasma chemical species are supplied from the plasma generated inside or outside the chamber to the substrate inside the chamber. The plasma may be an RF plasma obtained by exciting the plasma source gas using RF power. Examples of the RF plasma include capacitively coupled plasma (CCP), inductively coupled plasma (ICP), helicon wave plasma, and electron cyclotron resonance (ECR) plasma.

[0021] When a gas containing nitrogen atoms is used as the plasma source gas, the nitrogen chemical species (nitrogen radicals and / or nitrogen ions) in the plasma also function as the N source for the BN film. When forming a hexagonal BN film (h-BN film) on the substrate, the energy of the plasma chemical species can be adjusted so as not to break the basic skeleton of the first borazine compound.

[0022] After step ST1, step ST2 is performed. In step ST2, a second treatment is performed. The second treatment includes supplying plasma chemical species to the substrate without supplying the first treatment gas to the substrate. In step ST2, the adsorption of the first borazine compound on the substrate can be promoted. In step ST2, the reaction for forming a BN film from the first borazine compound can be promoted.

[0023] In step ST2, plasma may be generated from the same plasma source gas as the plasma source gas supplied into the chamber in step ST1, and plasma chemical species may be supplied from the plasma to the substrate. As shown in FIG. 1, the plasma source gas may be supplied over steps STa, ST1, and ST2, and RF power may be supplied over steps ST1 and ST2 for plasma generation.

[0024] In method MT1, after step ST2, step STb is performed. In step STb, similar to step STa, the chamber is purged.

[0025] As described above, in method MT1, after sequence SQ1 is performed x times (x ≥ 1), step ST3 is performed. Step ST3 may be a part of sequence SQ2 as described above, and sequence SQ2 may further include step STc.

[0026] In step ST3, a third process is performed. The third process includes supplying a second processing gas containing a second borazine compound containing an alkyl group to the substrate without supplying plasma chemical species to the substrate. In step ST3, the second borazine compound can adsorb on the surface of the BN film.

[0027] The second borazine compound may be, for example, an alkyl borazine compound in which part or all of the substituents R1 or R2 in the general formula represented by the following formula (3) are substituted with an alkyl group. The second borazine compound can be the alkyl borazine compound described above for the first borazine compound. The second borazine compound may be N,N’,N-trimethylborazine (TMB) having the structure represented by the above formula (2).

[0028]

Chemical formula

[0029] In method MT1, after step ST3, step STc is performed. In step STc, similar to step STa, the chamber is purged.

[0030] In method MT1, such cycle CY is repeated y times. The number of executions y of cycle CY may be predetermined. Alternatively, cycle CY may be repeated the number of times necessary for the film thickness of the BN film on the substrate W to reach a predetermined film thickness.

[0031] The second borazine compound adsorbed on the substrate in process ST3 has an effect of suppressing the growth of the BN film thereon (i.e., growth suppression effect). Also, in process ST3, due to the supply of the second processing gas, a distribution of the degree of the growth suppression effect is formed on the surface of the substrate provided by the protruding portion (see, for example, FIG. 7). This distribution can be adjusted, for example, by the supply conditions of the second processing gas in process ST3 and the like. In method MT1, due to the formation of the distribution of the degree of the growth suppression effect in process ST3 and the film formation in sequence SQ1, the step coverage (or conformality) of the BN film formed on the surface of the substrate is improved.

[0032] FIG. 2 is a timing chart showing a method for forming a BN film according to another exemplary embodiment. In FIG. 2, the states in which various gases are supplied and the state in which high-frequency (RF) power is supplied in a film formation method (hereinafter referred to as "method MT2") of one embodiment are shown by solid lines or dotted lines with arrows.

[0033] Method MT2 is different from the above-described method MT1 in that it includes a step ST2a of performing a second treatment before step ST1. Step ST2a is performed before step ST1 in sequence SQ1. In step ST2a, the second treatment is performed in the same manner as in step ST2. Other steps of method MT2 are the same as the corresponding steps of method MT1.

[0034] Sequence SQ1 of method MT2 may further include step STa and step STb, or may include step STb but not step STa, in the same manner as sequence SQ1 of method MT1. In the former case, that is, when sequence SQ1 of method MT2 includes step STa, step ST2a can be performed between step STa and step ST1.

[0035] As shown in FIG. 2, the plasma source gas may be supplied over steps STa, ST2a, ST1, and ST2, and RF power may be applied over steps ST2a, ST1, and ST2 for plasma generation.

[0036] Since method MT2 further includes step ST2a, the supply time of the plasma chemical species can be ensured to be long. In method MT2, step ST2a can be performed for the purpose of improving the flatness of the surface of the BN film formed on the surface of the substrate.

[0037] FIG. 3 is a timing chart showing a method for forming a BN film according to still another exemplary embodiment. In FIG. 3, the states in which various gases are supplied and the state in which high-frequency (RF) power is supplied in a film-forming method (hereinafter referred to as "method MT3") of one embodiment are shown by solid lines or dotted lines with arrows.

[0038] Method MT3 is different from the above-described method MT1 in that it includes step STd instead of step STa. That is, in method MT3, step STd is performed before step ST1. Other steps of method MT2 are the same as the corresponding steps of method MT1.

[0039] In step STd, a pre-treatment (Pre-flow) is performed. The pre-treatment includes supplying a first processing gas without supplying plasma chemical species to the substrate. In step STd, a plasma source gas may be supplied into the chamber. The plasma source gas is used to generate plasma therefrom in the subsequent step ST1. In step STd, a purge gas may be supplied into the chamber.

[0040] As shown in FIG. 3, the plasma source gas may be supplied over steps STd, ST1, and ST2, and RF power may be applied and supplied to steps ST1 and ST2 for plasma generation.

[0041] Since method MT3 further includes step STd, the supply time of the first processing gas can be ensured to be long. In method MT3, step STd can be performed for the purpose of further improving the step coverage of the BN film formed on the surface of the substrate.

[0042] In each cycle CY of the methods MT1 to MT3 described above, the film formation conditions for forming the BN film on the substrate may include at least one of the processing temperature of the substrate, the pressure in the chamber, the supply time (Depo time) of the first processing gas and plasma in step ST1, the supply time of plasma in step ST2, the supply time of the second processing gas in step ST3, and the supply flow rate of the second processing gas in step ST3. By setting these conditions to predetermined conditions, the conformality of the BN film on the surface of the substrate with respect to the surface can be enhanced according to the shape of the surface of the substrate.

[0043] Also, the supply time of the second processing gas in each step ST3 of the methods MT1 to MT3 may be shorter than the Depo time of step ST1. Even in this case, the growth inhibition effect of the BN film by the second borazine compound is effectively exerted. Therefore, the step coverage of the BN film can be further enhanced.

[0044] Also, the supply flow rate of the second processing gas in each step ST3 of the methods MT1 to MT3 may be smaller than the supply flow rate of the first processing gas in step ST1. Even in this case, the growth inhibition effect by the second borazine compound is effectively exerted. Therefore, the step coverage of the BN film can be further enhanced.

[0045] Also, the first borazine compound used in each of the methods MT1 to MT3 may contain an alkyl group. Also, the first borazine compound may be the same as the second borazine compound. In this case, it is possible to simply form a BN film using a single borazine compound in the methods MT1 to MT3.

[0046] Also, in methods MT1 to MT3, the supply time of the second processing gas in step ST3 may be 0.5 seconds or less. By adjusting the supply time of the second processing gas in step ST3 within the range of 0.5 seconds or less, the growth inhibition effect by the second borazine compound can be adjusted. Therefore, according to this method for forming a BN film, it is possible to form a BN film having higher step coverage. Note that the supply time of the second processing gas in step ST3 may be 0.1 seconds or less.

[0047] Also, in methods MT1 to MT3, by adjusting the processing temperature of the substrate, the pressure in the chamber, and Depo time, a hexagonal BN film (h-BN) can be formed, or an amorphous BN film (a-BN) can be formed.

[0048] Here, the results of investigating which of the h-BN film and the a-BN film is formed by changing the processing temperature of the substrate, the pressure in the chamber, and Depo time and performing the sequence SQ1 of method MT1 are shown. In this investigation, the film forming apparatus shown in FIG. 6 described later was used. Also, TMB gas was used as the source gas, and N2 gas was used as the plasma source gas. Further, the pressure in the chamber was changed in the range of 1.5 to 8 Torr, the processing temperature of the substrate (or the temperature of the mounting table 2) was changed in the range of 200°C to 400°C, and Depo Time was set to 2 seconds and 4 seconds, respectively. Note that the TMB flow rate was 20 sccm, and the RF power was 400 W. Also, the time of step STa and step STb was set to 3 seconds, and the time of step ST2 was set to 4 seconds.

[0049] FIG. 4 is a diagram showing which of h-BN and a-BN is formed depending on the pressure in the chamber and the processing temperature of the substrate when Depo time is 2 seconds. FIG. 5 is a diagram showing which of h-BN and a-BN is formed depending on the pressure in the chamber and the processing temperature of the substrate when Depo time is 4 seconds.

[0050] As shown in FIGS. 4 and 5, a-BN is likely to be formed under low-temperature and low-pressure conditions, while h-BN is likely to be formed under high-temperature and high-pressure conditions. Also, the longer the Depo time, the more likely a-BN is to be formed and the less likely h-BN is to be formed.

[0051] In methods MT1 to MT3, the Depo time may be 4 seconds or more, the pressure in the chamber may be 8 torr (800 Pa) or more, and the temperature of the substrate may be 200° C. or more. Even in this case, h-BN can be formed.

[0052] <Apparatus for forming boron nitride film> FIG. 6 is a diagram showing the configuration of a film-forming apparatus for a BN film according to one exemplary embodiment. The film-forming apparatus 100 shown in FIG. 6 is a film-forming apparatus that can be used to form a BN film in methods MT1 to MT3. The film-forming apparatus 100 includes a chamber 1, a gas supply mechanism 5, a plasma generation unit 6, and a control unit 7. The film-forming apparatus 100 may further include a mounting table 2, a shower head 3, and an exhaust unit 4.

[0053] The chamber 1 can accommodate the substrate W. 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.

[0054] 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 a table on which the substrate W can be mounted in a horizontal state, has a disk shape corresponding to the size of the substrate W, and is supported by a support member 23. This mounting table 2 is composed of a ceramic material such as aluminum nitride (AlN), or a metal material such as aluminum or nickel-based alloy, and a heater 21 for heating the substrate W is embedded inside. 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 extends below the chamber 1, and its lower end 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 where the substrate can be transferred shown by the one-dot chain line below it.

[0057] A flange portion 25 is attached to the position below the chamber 1 of the support member 23, and a bellows 26 that partitions the atmosphere inside the chamber 1 from the outside air and expands and contracts as the mounting table 2 moves up and down is provided between the bottom surface of the chamber 1 and the flange portion 25.

[0058] Near the bottom surface of the chamber 1, three (only two are shown) substrate support pins 27 are provided so as to 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.

[0059] By raising 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.

[0060] The shower head 3 supplies the processing gas in a shower-like manner 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 body portion 31 fixed to the ceiling wall 14 of the chamber 1 and a shower plate 32 connected below the shower body portion 31.

[0061] A gas diffusion space 33 is formed between the shower body portion 31 and the shower plate 32, and a gas introduction hole 36 provided so as to penetrate the center of the shower 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. In a state where the mounting table 2 exists at the processing position, a processing space S is formed between the shower plate 32 and the mounting table 2.

[0062] 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 processing, 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.

[0063] The gas supply mechanism 5 supplies the gas used for film formation to the shower head 3. That is, the gas supply mechanism 5 can supply the above-described first processing gas, second processing gas, plasma source gas, and purge gas into the processing space S in the chamber 1 via the shower head 3.

[0064] The gas supply mechanism 5 has a supply source 51 of the first processing gas, a supply source 52 of the second processing gas, a supply source 53 of the plasma source gas, and supply sources 54 and 55 of the purge gas. The purge gas may be a noble gas such as, for example, a purge gas.

[0065] One end of a gas line 51a is connected to a supply source 51. A valve 51b, a filter tank 51c, and a flow rate adjustment unit 51d are installed in the gas line 51a in this order from the downstream side.

[0066] One end of a gas line 52a is connected to a supply source 52. A valve 52b, a filter tank 52c, and a flow rate adjustment unit 52d are installed in the gas line 52a in this order from the downstream side. The gas line 51a and the gas line 52a merge on the downstream side of the valves 51b and 52b and are connected to one end of a gas line 56.

[0067] One end of a gas line 53a is connected to a supply source 53. A valve 53b, a filter tank 53c, and a flow rate adjustment unit 53d are installed in the gas line 53a in this order from the downstream side. The gas line 56 and the gas line 53a are connected to one end of a gas line 57. The other end of the gas line 57 is connected to a gas introduction hole 36 of a shower head 3.

[0068] One end of a gas line 54a is connected to a supply source 54. A valve 54b and a flow rate adjustment unit 54d are installed in the gas line 54a in this order from the downstream side. The other end of the gas line 54a is connected to the gas line 56.

[0069] One end of a gas line 55a is connected to a supply source 55. A valve 55b and a flow rate adjustment unit 55d are installed in the gas line 55a in this order from the downstream side. The other end of the gas line 55a is connected to the downstream side of the valve 53b of the gas line 53a.

[0070] During the film formation process of the BN film in the film forming apparatus 100, the valves 54b and 55b are always open. Also, during the film formation process, purge gas from the gas lines 54a and 55a is constantly supplied into the chamber 1 through the gas lines 56 and 53a.

[0071] Valves 51b, 52b, and 53b are configured as high-speed on-off valves that rapidly open and close the corresponding gas lines. Valves 54b and 55b are normal on-off valves.

[0072] Filter tanks 51c, 52c, and 53c are each for temporarily storing the first processing gas, the second processing gas, and the plasma source gas before supplying them into chamber 1.

[0073] By storing gas in filter tank 51c, 52c, or 53c to raise the pressure inside to a predetermined pressure, and then opening valve 51b, 52b, or 53c, each gas can be discharged into chamber 1. Thereby, a large flow rate of gas can be stably supplied to chamber 1.

[0074] Flow rate adjustment units 51d, 52d, 53d, and 54d are constituted by, for example, mass flow controllers, and adjust and control the flow rate of the gas flowing through the corresponding gas lines.

[0075] Plasma generation unit 6 includes a power supply line 61 connected to the shower main body 31 of shower head 3, a matcher 62 and a high-frequency (RF) power supply 63 connected to power supply line 61. By supplying high-frequency (RF) power from RF power supply 63 to shower head 3, a high-frequency (RF) electric field is formed in the processing space S between shower head 3 and mounting table 2, and by this RF electric field, plasma of the plasma source gas is generated as capacitively coupled plasma. 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.

[0076] Supply source 53 and plasma generation unit 6 function as a plasma supply mechanism that generates plasma from the plasma source gas and supplies plasma chemical species from the plasma to substrate W.

[0077] 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.

[0078] The storage device stores parameters for various processes executed by the film forming apparatus 100. Further, the storage device has a storage medium in which a program for controlling the processes executed by the film forming apparatus 100, that is, a process recipe, is stored. 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.

[0079] The control unit 7 is configured to repeatedly execute the cycle CY by controlling the gas supply mechanism 5 and the plasma generation unit 6 in a state where the substrate W is accommodated in the chamber 1, and execute the film forming process of the BN film.

[0080] An example of a film forming method using the film forming apparatus 100 as described above will be described below. In one example, first, the substrate W is prepared in the chamber 1 of the film forming apparatus 100. Specifically, the gate valve 12 is opened, and the substrate W is carried into the chamber 1 through the carry-in outlet 11. The carry-in of the substrate W is performed by a transfer device (not shown) through the carry-in outlet 11. The carried-in substrate W is placed on the mounting table 2. Next, the transfer device retracts from the space in the chamber 1, and the mounting table 2 is lifted to the processing position. Then, the gate valve 12 is closed, and the chamber 1 is evacuated. Thereafter, the mounting table 2 is heated by the heater 21, and the temperature of the mounting table 2 (substrate temperature) is adjusted to a desired temperature.

[0081] In a state where the substrate W is thus prepared in the chamber 1 of the film forming apparatus 100, the film forming process can be started. Hereinafter, an example of the film forming process when performing the method MT1 as shown in FIG. 1 will be described.

[0082] First, in step STa, chamber 1 is purged. In step STa, purge gas can be supplied from supply sources 54 and 55 through gas lines 54a and 55a and shower head 3 to the processing space S. The purge gas may be continuously supplied during sequences SQ1 and SQ2.

[0083] In step STa, the first processing gas may be flowed into the exhaust line of the film forming apparatus 100. Alternatively, in step STa, the first processing gas may be filled into the filter tank of the film forming apparatus 100. Also, in step STa, plasma source gas may be supplied into chamber 1.

[0084] After step STa, step ST1 is performed. In step ST1, the first process is performed. In step ST1, the first processing gas can be supplied from supply source 51 through gas line 51a and shower head 3 to the processing space S. Also, plasma source gas is supplied from supply source 53 through gas line 53a and shower head 3 to the processing space S, and RF power is supplied from the RF power supply 63 of the plasma generation unit 6 to the shower head 3. Thereby, the first processing gas and plasma chemical species are supplied to the substrate W.

[0085] After step ST1, step ST2 is performed. In step ST2, the second process is performed. In step ST2, plasma chemical species are supplied to the substrate W. Also, in step ST2, valve 51b is closed and the supply of the first processing gas is stopped.

[0086] After step ST2, step STb is performed. In step STb, similar to step STa, the chamber is purged. In step STb, the supply of RF power by the RF power supply 63 is stopped, and valve 53b is closed to stop the supply of plasma source gas. Thereby, a state is formed in which only the purge gas is supplied to the processing space S, and chamber 1 is purged.

[0087] In step ST3, the third process is performed. In step ST3, the second processing gas can be supplied from the supply source 52 to the processing space S through the gas line 52a and the shower head 3. In step ST3, a purge gas may be supplied.

[0088] Next, step STc is performed. In step STc, similar to step STa, the purge of chamber 1 is performed. In step STc, the valve 52b is closed and the supply of the second processing gas is stopped. Thereby, a state is formed in which only the purge gas is supplied to the processing space S, and the purge of chamber 1 is performed.

[0089] In the case of the above method MT2, after step STa of purging chamber 1, step ST2a of supplying plasma species to the substrate W is performed. In step ST2a, RF power is supplied from the RF power supply 63 of the plasma generation unit 6 to the shower head 3 in a state where the plasma source gas is supplied to the processing space S.

[0090] In the case of the above method MT3, instead of step ST1, a preflow step (step STd) of supplying a first processing gas to the processing space S in addition to a purge gas (or a purge gas and a plasma source gas) is performed. In step STd, the first processing gas can be supplied from the supply source 51 to the processing space S through the gas line 51a and the shower head 3.

[0091] As described above, various exemplary embodiments have been described. However, without being limited to the above-described exemplary embodiments, various additions, omissions, substitutions, and changes may be made. Also, it is possible to form other embodiments by combining elements in different embodiments.

[0092] For example, although Methods MT1, MT2, and MT3 were described as examples of the method for forming a BN film, it is also possible to adopt methods other than these film-forming processes. That is, the sequence SQ1 may include a step ST1 of supplying a first processing gas containing a first borazine compound and plasma species to a substrate housed in a chamber, and a step ST2 of supplying plasma species without supplying the first processing gas to the substrate. The sequence SQ2 may include a step ST3 of supplying a second processing gas without supplying plasma species to the substrate.

[0093] Also, in the BN film forming apparatus 100, a supply source 51 and a supply source 52 are respectively provided as supply mechanisms for the first processing gas and the second processing gas. However, the supply mechanisms for the first processing gas and the second processing gas do not necessarily have to be composed of a plurality of supply mechanisms and may be composed of a single supply mechanism. For example, when both the first borazine compound and the second borazine compound are TMB, it is possible to use a single supply source as the supply mechanism for the first processing gas and the second processing gas.

[0094] Also, the BN film forming apparatus may be a film forming apparatus other than a single wafer type film forming apparatus, for example, a batch type film forming apparatus. Further, the BN film forming apparatus is not limited to a capacitively coupled plasma processing apparatus. For example, the BN film forming apparatus may be any type of plasma processing apparatus such as an inductively coupled plasma processing apparatus, a surface wave plasma type processing apparatus configured to generate plasma using a surface wave such as a microwave, etc. Also, the BN film forming apparatus may be a remote plasma type plasma processing apparatus configured to supply plasma generated at another location to the substrate.

[0095] <Evaluation Experiment> Hereinafter, the experiments conducted for the evaluation of the formation of the BN film will be described.

[0096] FIG. 7 is a schematic diagram of a cross-sectional TEM image of a sample substrate WP in the state after the formation of a BN film in the experiment. As shown in FIG. 7, the sample substrate WP was a substrate including a base region B formed of silicon and a protrusion PR formed of silicon oxide and extending upward from the base region B. In the experiment, a BN film F was formed on the surface of such a sample substrate WP. Note that the protrusion PR had a structure including a pair of side surfaces and an upper surface extending from their upper ends.

[0097] In the experiment, the thickness W of the BN film F at the upper surface, that is, the top T T , the thickness W of the BN film F at the middle portion Md in the height direction of the side surface of the protrusion PR M , the thickness W of the BN film F at the bottom Bt of the side surface of the protrusion PR B were measured. And the ratio (%) of W T to W M and the ratio (%) of W T to W B were obtained. In the following description, "W M / W T " indicates the ratio of W T to W M , and "W B / W T " indicates the ratio of W T to W B .

[0098] In the following experimental examples and comparative experimental examples, N,N’,N’’-trimethylborazine (TMB) was used as the first processing gas and the second processing gas, NH3 gas was used as the plasma source gas, and Ar gas was used as the purge gas to form the BN film F.

[0099] (Comparative Experimental Example) In the comparative experimental example, the following film-forming treatment was performed on the sample substrate WP to form a BN film F on the sample substrate WP. In the comparative experimental example, a first treatment (step ST1) of supplying TMB gas and plasma chemical species to the sample substrate WP, a second treatment (step ST2) of supplying plasma chemical species to the sample substrate WP without supplying TMB gas, and a purge step (step STc) of purging the chamber were repeated in this order until a BN film F with a predetermined film thickness was obtained.

[0100] Details of the treatment conditions in the comparative experimental example are shown below. Here, Depo time is the time of the first treatment (step ST1), Plasma time is the time of the second treatment (step ST2), and Purge time is the time of the purge step (step STb).

[0101] Substrate temperature: 400 °C Stage gap: 6 mm Pressure: 6 torr (800 Pa) TMB flow rate: 20 sccm NH3 flow rate: 30,000 sccm Depo time: 2 seconds Plasma time: 16 seconds Purge time: 6 seconds RF power: 400 W CF-Ar flow rate: 1500 sccm Bottom Ar flow rate: 100 sccm

[0102] In the film-forming method according to this comparative experimental example, W M / W T = 46%, W B / W T = 43% were obtained.

[0103] (Experimental Example 1) In Experimental Example 1, the film-forming treatment of Method MT1 was performed on the sample substrate WP to form a BN film F on the sample substrate WP.

[0104] In Sequence SQ1 of Experimental Example 1, a first process (step ST1) of supplying TMB gas and plasma chemical species to the sample substrate WP, a second process (step ST2) of supplying plasma chemical species to the sample substrate WP without supplying TMB gas, and a purge process (step STc) of purging the chamber were performed in this order. In Sequence SQ2, a third process (step ST3) of supplying TMB gas without supplying plasma chemical species and a purge process (step STd) of purging the chamber were performed in this order.

[0105] Details of the processing conditions in Experimental Example 1 are shown below. Hereinafter, Flow time is the time of the third process (step ST3), and x is the number of times of Sequence SQ1 in one cycle (cycle CY).

[0106] Substrate temperature: 400 °C Stage gap: 6 mm Pressure: 6 torr (800 Pa) TMB flow rate (step ST1): 20 sccm TMB flow rate (step ST3): 10 sccm NH3 flow rate: 3000 sccm Depo time: 2 seconds Plasma time: 16 seconds Purge time: 6 seconds Flow time: 0.1 seconds RF power: 400 W CF-Ar flow rate: 1500 sccm Bottom Ar flow rate: 100 sccm x: 5

[0107] In the film formation method according to Experimental Example 1, W M / W T = 55%, W B / W T = 49% was obtained. That is, it was confirmed that in any of the values of W M / W T and W B / W T it is superior to the comparative experimental example, and the step coverage is improved.

[0108] (Experimental Example 2) In Experimental Example 2, the experiment similar to Experimental Example 1 was conducted by changing the pressure in the above Experimental Example 1 from 6 torr (800 Pa) to 11 torr (1467 Pa) and changing x from 5 to 1.

[0109] In the film formation method according to Experimental Example 2, W M / W T = 53%, and the result of W B / W T = 47% was obtained. Also in Experimental Example 2, it was confirmed that W M / W T and W B / W T were superior to the comparative experimental example in terms of numerical values, and the step coverage was improved.

[0110] From the above results, it was confirmed that the step coverage was improved by the film formation process including the third process (process ST3) in sequence SQ2.

[0111] In Experimental Example 1 and Experimental Example 2, it is considered that the above growth suppression effect significantly acted on the top T of the protrusion PR. Further, in the above Experimental Example 1 and Experimental Example 2, an experiment for measuring the growth suppression effect of the BN film was conducted. FIG. 8 is a diagram showing the experimental results of measuring the growth suppression effect of the BN film.

[0112] In this experiment, the film formation amount (change in film thickness) of the BN film per sequence was defined as GPC, and the ratio of GPC of Experimental Example 1 and Experimental Example 2 to the GPC of the comparative experimental example was calculated. The calculation was performed for each of the top T, the middle side surface Ms, and the bottom side surface Bs of the protrusion PR. As shown in FIG. 8, in both Experimental Example 1 and Experimental Example 2, the GPC compared to the comparative experimental example was smaller at the top T. From this result, it can be seen that the growth suppression effect significantly acted on the top T of the protrusion PR.

[0113] (Experimental Example 3) In Experimental Example 3, the number x of times of sequence SQ1 in one cycle was changed to various values, and GPC was measured to evaluate the change in the growth inhibition effect according to the number x of times of sequence SQ1. In Experimental Example 3, instead of the sample substrate WP schematically shown in FIG. 7, another sample substrate (not shown) having a flat surface was used, and the growth inhibition effect of the BN film on the flat surface was evaluated. In Experimental Example 3, the Flow time, which is the time of the third process (process ST3), was set to 1 second. Regarding other conditions in Experimental Example 3, they are the same as the corresponding conditions in Experimental Example 1.

[0114] FIG. 9 is a diagram showing the results of an experiment measuring the relationship between the number x of times of sequence SQ1 in one cycle and GPC. In FIG. 9, "w / o" represents the result of an experiment in which only sequence SQ1 was performed. As shown in FIG. 9, the smaller the value of x, the smaller the GPC. That is, since sequence SQ2 is performed more frequently as the value of x is smaller, it was confirmed that the growth inhibition effect of the BN film is remarkably exhibited.

[0115] (Experimental Example 4) In Experimental Example 4, using the same sample substrate as in Experimental Example 3, the time (Flow time) of the third process (process ST3) in sequence SQ2 was changed, and GPC was measured. In Experimental Example 4, the number x of times of sequence SQ1 in one cycle was 5 times. Regarding other conditions in Experimental Example 4, they are the same as the corresponding conditions in Experimental Example 1.

[0116] FIG. 10 is a diagram showing the results of an experiment measuring the relationship between Flow time and GPC. As shown in FIG. 10, when Flow time is between 0.1 second and 0.5 seconds, GPC decreases as the time of Flow time increases. Even when Flow time is 0.5 seconds or more, there is a growth inhibition effect of the BN film, but the effect is saturated, and it was confirmed that GPC does not change even when Flow time is increased.

[0117] Therefore, it was confirmed that the growth inhibition effect can be adjusted to a desired level by changing Flow time to 0.5 seconds or less.

[0118] (Experimental Example 5) In Experimental Example 5, using the same sample substrate as in Experimental Example 3, the flow rate of TMB in step ST3 in sequence SQ2 was changed to measure GPC, and the relationship between the flow rate of TMB in step ST3 and the growth inhibition effect was evaluated. The measurement of GPC was carried out for two patterns when the flow time was 0.1 second and 1 second. In Experimental Example 5, the number of times x of sequence SQ1 in one cycle was set to 5 times. Regarding other conditions in Experimental Example 5, they were the same as the corresponding conditions in Experimental Example 1.

[0119] Figure 11 is a diagram showing the results of an experiment measuring the relationship between the flow rate of TMB in step ST3 and GPC. As shown in Figure 11, it can be seen that GPC does not change due to the change in the flow rate of TMB in step ST3, whether the flow time is 1 second or 0.1 second.

[0120] Therefore, it was confirmed that the growth inhibition effect can be sufficiently exerted when the flow rate of TMB is 5 sccm. Also, as in Experimental Example 5, when the flow rate of TMB in step ST3 is made smaller than the flow rate of TMB in step ST1, it was confirmed that the growth inhibition effect of the BN film can be obtained without depending on the flow rate of TMB.

[0121] <Effect of Pressure in Step ST3> Figure 12 is a diagram showing the results of an experiment measuring the relationship between the pressure in step ST3 and GPC using the same sample substrate as in Experimental Example 3. In the legend, "x" means the number of times of sequence SQ1 in one cycle, and "flow" means the flow time. In the four experiments whose measurement results are shown in Figure 12, conditions other than x and the flow time were the same as the corresponding conditions in Experimental Example 1.

[0122] As shown in Figure 12, it was confirmed that the higher the pressure in step ST3, the more the GPC tends to improve. (Experimental Example 6) In Experimental Example 6, using the same sample substrate as in Experimental Example 3, the number x of times of Sequence SQ1 in one cycle was set to 1, the Flow time was set to 0.1 second, and the relationship between the pressure in Process ST3 and GPC was measured. Regarding other conditions in Experimental Example 6, they were the same as the corresponding conditions in Experimental Example 1.

[0123] FIG. 13 is a diagram showing the results of an experiment measuring the relationship between the pressure in Process ST3 and GPC. As shown in FIG. 13, GPC improved as the pressure in Process ST3 was increased. Therefore, it was confirmed that by adjusting the pressure in Process ST3, the growth suppression effect of the BN film can be adjusted.

[0124] Also, according to FIGS. 12 and 13, it was confirmed that depending on the value of the number x of times of Sequence SQ1 or the Flow time in one cycle, pressure dependence occurs in GPC. Therefore, it was confirmed that under the values of x and Flow time where pressure dependence occurs in GPC, the growth suppression effect of the BN film can be adjusted by adjusting the pressure.

[0125] Here, various exemplary embodiments included in the present disclosure are described in [E1] to [E18] below.

[0126] [E1] (a) A step of executing a sequence, the sequence including: (a1) A step of supplying a first processing gas containing a first borazine compound and plasma chemical species to a substrate disposed in a chamber of a film forming apparatus to form a boron nitride film on the substrate; (a2) A step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate; and including this step; (b) A step of supplying a second processing gas containing a second borazine compound containing an alkyl group to the substrate without supplying the plasma chemical species to the substrate; (c) A step of repeating a cycle including the above (a) and (b); and including a method for forming a boron nitride film.

[0127] [E2] In the above cycle, the film formation conditions for forming the boron nitride film on the substrate include at least one of the processing temperature of the substrate, the pressure in the chamber, the supply time of the first processing gas and the plasma chemical species in (a1), the supply time of the plasma chemical species in (a2), the supply time of the second processing gas in (b), and the supply flow rate of the second processing gas in (b). The method for forming a boron nitride film according to E1.

[0128] [E3] The supply time of the second processing gas in (b) is shorter than the supply time of the first processing gas and the plasma chemical species in (a1). The method for forming a boron nitride film according to E1 or E2.

[0129] [E4] The supply flow rate of the second processing gas in (b) is smaller than the supply flow rate of the first processing gas in (a1). The method for forming a boron nitride film according to E1 or E2.

[0130] [E5] The sequence further includes a step of purging the chamber after (a1) and (a2). The cycle further includes a step of purging the chamber after (b). The method for forming a boron nitride film according to any one of E1 to E4.

[0131] [E6] The sequence is Before (a1), a step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate, and After (a1) and (a2), a step of purging the chamber, and further includes The cycle further includes a step of purging the chamber after (b). The method for forming a boron nitride film according to any one of E1 to E4. [E7] The sequence further includes: before the step (a1), a step of supplying the first processing gas to the substrate without supplying the plasma to the substrate; after the steps (a1) and (a2), a step of purging the chamber; and the cycle further includes a step of purging the chamber after the step (b). A method for forming a boron nitride film according to any one of E1 to E4.

[0132] [E8] A method for forming a boron nitride film according to any one of E1 to E8, wherein the first borazine compound contains an alkyl group.

[0133] [E9] A method for forming a boron nitride film according to E8, wherein the first borazine compound is the same as the second borazine compound.

[0134] [E10] A method for forming a boron nitride film according to E9, wherein the first borazine compound and the second borazine compound are N,N’,N’’-trimethylborazine.

[0135] [E11] A method for forming a boron nitride film according to any one of E1 to E10, wherein the plasma chemical species is a plasma chemical species generated from a gas containing at least one selected from the group consisting of nitrogen, hydrogen, and a noble gas.

[0136] [E12] A method for forming a boron nitride film according to E11, wherein the plasma chemical species is a plasma chemical species generated from the gas containing at least one selected from the group consisting of N2, H2, and NH3.

[0137] [E13] A method for forming a boron nitride film according to E12, wherein the plasma chemical species is a plasma chemical species generated from the gas containing NH3.

[0138] [E14] The method for forming a boron nitride film according to any one of E1 to E13, wherein the supply time of the second processing gas in (b) is 0.5 seconds or less.

[0139] [E15] The method for forming a boron nitride film according to E14, wherein the supply time of the second processing gas in (b) is 0.1 seconds or less.

[0140] [E16] The method for forming a boron nitride film according to any one of E1 to E15, wherein the surface of the substrate on which the boron nitride film is formed includes the side surface of a protrusion extending upward from a base region and the upper surface of the protrusion.

[0141] [E17] In (a1), the supply time of the first processing gas and the plasma chemical species, the pressure in the chamber, and the processing temperature of the substrate are set to a predetermined supply time, pressure, and temperature so as to form a hexagonal boron nitride film as the boron nitride film. The method for forming a boron nitride film according to any one of E1 to E16.

[0142] [E18] A chamber, A gas supply mechanism connected to the chamber, A plasma generation unit configured to generate plasma from a gas in the chamber, A control unit, Comprising, The control unit controls the gas supply mechanism and the plasma generation unit in a state where a substrate is accommodated in the chamber, (a) A step of executing a sequence, and the sequence includes (a1) A step of supplying a first processing gas containing a first borazine compound and plasma chemical species to the substrate, (a2) A step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate, Including, and the step, (b) A step of supplying a second processing gas containing a second borazine compound containing an alkyl group to the substrate without supplying the plasma chemical species to the substrate; (c) A step of repeating the cycle including the above (a) and (b); configured to perform a film-forming process of a boron nitride film including; a film-forming apparatus.

[0143] From the above description, it will be understood that various embodiments of the present disclosure are described herein for illustrative purposes and that various changes can be made without departing from the scope and spirit of the present disclosure. Therefore, the various embodiments disclosed herein are not intended to be limiting, and the true scope and spirit are indicated by the appended claims.

Description of Reference Numerals

[0144] 1... chamber, 2... mounting table, 3... shower head, 4... exhaust section, 5... gas supply mechanism, 6... plasma generation section, 7... control section, 51 - 55... supply sources, 100... film-forming apparatus, W... substrate.

Claims

1. (a) A step of executing a sequence, the sequence comprising: (a1) A step of supplying a first processing gas containing a first borazine compound and plasma chemical species to a substrate to form a boron nitride film on the substrate disposed in a chamber of a film forming apparatus; (a2) A step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate; The step including these; (b) A step of supplying a second processing gas containing a second borazine compound containing an alkyl group to the substrate without supplying the plasma chemical species to the substrate; (c) A step of repeating a cycle including the above (a) and (b); A method for forming a boron nitride film including these.

2. The film forming conditions for forming the boron nitride film on the substrate in the cycle include at least one of the processing temperature of the substrate, the pressure in the chamber, the supply time of the first processing gas and the plasma chemical species in (a1), the supply time of the plasma chemical species in (a2), the supply time of the second processing gas in (b), and the supply flow rate of the second processing gas in (b). The method for forming a boron nitride film according to Claim 1.

3. The method for forming a boron nitride film according to Claim 1 or 2, wherein the supply time of the second processing gas in (b) is shorter than the supply time of the first processing gas and the plasma chemical species in (a1).

4. The method for forming a boron nitride film according to Claim 1 or 2, wherein the supply flow rate of the second processing gas in (b) is smaller than the supply flow rate of the first processing gas in (a1).

5. The sequence further includes a step of purging the chamber after (a1) and (a2), The cycle further includes a step of purging the chamber after (b), The method for forming a boron nitride film according to Claim 1 or 2.

6. The sequence includes: Before (a1), a step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate; After (a1) and (a2), a step of purging the chamber; Further including these, The cycle further includes a step of purging the chamber after (b), The method for forming a boron nitride film according to Claim 1 or 2.

7. The sequence includes: Before (a1), a step of supplying the first processing gas to the substrate without supplying the plasma to the substrate; After the steps (a1) and (a2), a step of purging the chamber is further included. which further includes The cycle further includes a step of purging the chamber after step (b). The method for forming a boron nitride film according to claim 1 or 2.

8. The method for forming a boron nitride film according to claim 1 or 2, wherein the first borazine compound contains an alkyl group.

9. The method for forming a boron nitride film according to claim 8, wherein the first borazine compound is the same as the second borazine compound.

10. The method for forming a boron nitride film according to claim 9, wherein the first borazine compound and the second borazine compound are N,N',N''-trimethylborazine.

11. The method for forming a boron nitride film according to claim 1 or 2, wherein the plasma chemical species is a plasma chemical species generated from a gas containing at least one selected from the group consisting of nitrogen, hydrogen, and a noble gas.

12. The plasma species is N ２ , H ２ and N.H. ３ 12. The method for forming a boron nitride film according to claim 11, wherein the plasma chemical species generated from the gas includes at least one selected from the group consisting of:

13. The plasma chemical species is NH ３ The method for forming a boron nitride film according to claim 12, wherein the plasma chemical species is a plasma chemical species generated from the gas containing

14. The method for forming a boron nitride film according to claim 1 or 2, wherein the supply time of the second processing gas in step (b) is 0.5 seconds or less.

15. The method for forming a boron nitride film according to claim 14, wherein the supply time of the second processing gas in step (b) is 0.1 seconds or less.

16. The method for forming a boron nitride film according to claim 1, wherein the surface of the substrate on which the boron nitride film is formed includes the side surface of a protrusion extending upward from a base region and the upper surface of the protrusion.

17. In step (a1), the supply time of the first processing gas and the plasma chemical species, the pressure in the chamber, and the processing temperature of the substrate are set to a predetermined supply time, pressure, and temperature so as to form a hexagonal boron nitride film as the boron nitride film. The method for forming a boron nitride film according to claim 1 or 16.

18. A chamber, A gas supply mechanism connected to the chamber, A plasma generation unit configured to generate plasma from a gas in the chamber, A control unit, comprising The control unit controls the gas supply mechanism and the plasma generation unit in a state where a substrate is accommodated in the chamber, (a) A step of executing a sequence, and the sequence includes (a1) A step of supplying a first processing gas containing a first borazine compound and plasma chemical species to the substrate, (a2) A step of supplying the plasma chemical species to the substrate without supplying the first processing gas to the substrate. including the step, (b) a step of supplying a second processing gas containing a second borazine compound containing an alkyl group to the substrate without supplying the plasma chemical species to the substrate; (c) a step of repeating the cycle including the steps (a) and (b); configured to perform a film formation process of a boron nitride film including a film forming apparatus.

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