Method for forming a titanium film, and apparatus for forming a titanium film

Abstract

To provide a technology for forming a titanium film in a recess which is formed in a substrate and of which aspect ratio is 25 or more.SOLUTION: A method for forming a titanium film alternately repeats several times: supplying a titanium raw material gas with respect to a substrate formed with a recess of which aspect ratio is 25 or more and applying high-frequency power with respect to a space supplied with the raw material gas while repeating turning on and off alternately to transform the raw material gas into a plasma; and stopping the application of the high-frequency power for a longer period than one cycle of the turning on and off of the high-frequency power, to deposit the titanium film in the recess.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In the manufacturing process of devices for power devices and integrated circuits, a process of forming a metal film, such as a titanium film, may be performed in recesses such as trenches and via holes formed on the surface of a semiconductor wafer (hereinafter referred to as "wafer") which is a substrate. On the other hand, with the increase in high performance, high functionality, high integration, etc. of these devices, the aspect ratio, which is the ratio of the width dimension to the depth dimension of the recess, tends to increase.

[0003] For example, Patent Document 1 describes a technique for forming a Ti film in a contact hole formed in a Si substrate by introducing TiCl4 gas into a chamber in which the Si substrate is disposed and then generating plasma in the chamber. This Ti film becomes a TiSi film by reacting with the underlying Si. Further, Patent Document 2 describes a technique for alternately repeating the supply of a titanium compound gas to a Si wafer in which contact holes are formed and the subsequent supply of hydrogen gas plasma to react with silicon on the surface of the Si wafer to form a titanium silicide film.

Prior Art Documents

Patent Documents

[0004]

Patent Document

Patent Document

Summary of the Invention

Problems to be Solved by the Invention

[0005] This disclosure provides a technique for forming a titanium film in recesses with an aspect ratio of 25 or more formed on a substrate. [Means for solving the problem]

[0006] This disclosure relates to a method for forming a titanium film in a recess formed on the surface of a substrate, The aspect ratio, which is the ratio of the depth dimension to the width dimension, is 25 or greater. The side walls are exposed with silicon or silicon oxide, and the bottom surface is also exposed with silicon. With respect to the substrate in which the recess is formed, It is titanium tetrachloride gas. The process of supplying titanium raw material gas, The method includes the steps of: applying high-frequency power to the space to which the titanium raw material gas is supplied, while the process of supplying the titanium raw material gas is being carried out, in an alternating on / off cycle, to plasmaize the titanium raw material gas; and then stopping the application of the high-frequency power for a period longer than one cycle of the on / off cycle of the high-frequency power, and repeating this process multiple times to form the titanium film in the recess. [Effects of the Invention]

[0007] According to this disclosure, a titanium film can be formed in recesses with an aspect ratio of 25 or more formed on a substrate. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the deposition process of a Ti film related to the comparative form. [Figure 2] This is a schematic diagram showing the process of depositing the Ti film related to this disclosure. [Figure 3] This is a longitudinal cross-sectional side view showing an example of the configuration of a Ti film deposition apparatus. [Figure 4] This is a time chart showing the application of high-frequency power during the deposition of a Ti film. [Figure 5] This is a schematic diagram showing the deposition process of a Ti film according to another embodiment. [Figure 6] This is an electron microscope image showing the experimental results of depositing a Ti film into a recessed area. [Modes for carrying out the invention]

[0009] <Method for forming a Ti film in a comparative form> Before describing the titanium (Ti) film deposition method related to this disclosure, we will explain the challenges of the film deposition method related to the comparative form. Figure 1 shows, for example, a case in which a Ti film 61a is formed in a recess 50 formed on the surface of a wafer by a film deposition method according to the comparative example, when manufacturing a power device. In this example, the recess 50 is formed in the silicon member 51 that constitutes the wafer W. Therefore, the silicon member 51 is exposed on the side walls and bottom surface of the recess 50. In this example, the Ti film 61a is formed in the recess 50 where the aspect ratio, which is the ratio of the depth dimension H to the width dimension W, is 25 or more. In the case of a power device, the width dimension W of the recess 50 is 0.4 μm within the range of 0.1 to 5 μm, and the depth dimension H An example is a case where the depth is 10 μm within the range of 2.5 to 125 μm. H The range is the minimum range in which the aspect ratio is 25 when the width dimension W is 0.1 to 5 μm, and a deeper recess 50 may be formed.

[0010] In the comparative configuration, a Ti film 61a is formed by a known plasma CVD (Chemical Vapor Deposition) method. In this method, titanium tetrachloride (TiCl4) gas, which is the titanium raw material gas, and hydrogen (H2) gas, which is the reaction gas (reducing gas), are continuously supplied to the processing space. Then, high-frequency power of approximately several hundred kHz to several GHz, and 800 to 1300 W is applied to plasmaize the gas. At this time, the wafer W is heated to a temperature of approximately 450 to 650°C.

[0011] By the above-described process, highly reactive TiCl₂ radicals 7a are abundantly formed in the vicinity of the recess 50, and the formation of the Ti film 61a proceeds. At this time, in an environment where the formation of the Ti film 61a by the highly reactive TiCl₂ radicals 7a is dominant, the reaction proceeds rapidly, and Ti may be deposited before the TiCl₂ radicals 7a enter the lower region within the recess 50. As a result, as shown in FIG. 1, the Ti film 61a is concentratedly formed near the opening of the recess 50, the entry of the TiCl₂ radicals 7a into the recess 50 is inhibited, and there is a high possibility that it becomes difficult to form the Ti film 61 having a uniform film thickness.

[0012] This tendency becomes more likely to occur as the aspect ratio of the recess 50 increases. In the recess 50 having an aspect ratio of 25 or more, which can be said to be a so-called "ultra-deep hole", the formation of the Ti film 61 having a uniform film thickness is a highly difficult process. When the width dimension W is 0.4 μm, the depth dimension H of the recess 50 generally called a "deep hole" is at most about 5 μm (aspect ratio of 12.5).

[0013] <Film forming apparatus> In the film forming method according to the present disclosure, by devising the supply of high-frequency power, while proceeding with the film formation by TiCl₃ radicals 7b having lower reactivity than the TiCl₂ radicals 7a, the TiCl₃ radicals 7b are also allowed to enter the recess 50 (FIG. 2). Thereby, a Ti film 61 having a uniform film thickness is formed in the recess 50 having a high aspect ratio. The configurations of the silicon member 51 and the recess 50 in FIG. 2 are the same as those in the example described using FIG. 1. Hereinafter, a configuration example of a film forming apparatus 1 for implementing the film forming method will be described with reference to FIG. 3.

[0014] FIG. 1 is a longitudinal side view of the film forming apparatus 1 in this example. This film forming apparatus 1 is configured as an apparatus for continuously supplying TiCl₄ gas, H₂ gas, and argon (Ar) gas to the surface of the wafer W and forming a Ti film 61 by the plasma CVD method. The film forming apparatus 1 includes a substantially cylindrical processing container 10 made of metal that has corrosion resistance to chlorine and is grounded. At the center of the bottom surface of the processing container 10, an exhaust chamber 11, for example, in a cylindrical shape protruding downward, is formed, and an exhaust passage 12 is connected to the side surface of the exhaust chamber 11. Connected to the exhaust passage 12 is a vacuum exhaust unit 13 including a pressure regulating valve, for example, a butterfly valve, and is configured to be able to decompress the inside of the processing container 10 to a preset vacuum pressure. The processing of the wafer W is performed in the space inside this processing container 10.

[0015] On the side surface of the processing container 10, a carry-in / out port 14 for carrying in and out the wafer W between the processing container 10 and a vacuum transfer chamber (not shown) is formed. The carry-in / out port 14 is configured to be openable and closable by a gate valve 15. Further, inside the wall portion constituting the processing container 10, a heater 16 for adjusting the temperature inside the processing container 10 is embedded.

[0016] Also, inside the processing container 10, a mounting table 2 for holding the wafer W substantially horizontally is provided. The mounting table 2 is supported by a support portion 21 extending from the bottom of the exhaust chamber 11. A heater 20, which is a heating portion, is embedded in the mounting table 2, and the wafer W can be heated to a set temperature. In this example, the heating temperature of the wafer W is set to, for example, 500 °C within the range of 400 to 800 °C.

[0017] Also, a high-frequency power supply 23 for supplying high-frequency power for ion drawing is connected to the mounting table 2 via an aligner 22. Further, the mounting table 2 is provided with lifting pins (not shown) for holding and lifting the wafer W on the mounting table 2. By raising and lowering the lifting pins, the wafer W can be transferred between the mounting table 2 and an external transfer mechanism (not shown). [[ID=十五]]

[0018] Also, on the ceiling surface of the processing container 10, a flat disk-shaped shower head 3 for supplying a substrate processing gas toward the wafer W is provided. The shower head 3 is attached to the processing container 10 via an insulating member 17. A diffusion chamber 31 for diffusing gas is formed inside the shower head 3. Numerous discharge holes 32 for discharging gas toward the wafer W are also provided on the bottom surface of the shower head 3. Furthermore, a heater 36 is embedded in the front surface of the shower head 3.

[0019] A high-frequency power supply 34, which supplies high-frequency power for plasma formation, is connected to the showerhead 3 described above via a matching unit 33. In other words, the film deposition apparatus 1 of this disclosure consists of a showerhead 3 which forms the upper electrode and a mounting table 2 which forms the lower electrode, forming a parallel plate type plasma processing apparatus. A wafer W is placed in the space between the showerhead 3 and the mounting table 2, and by supplying TiCl4 gas, H2 gas, etc., and applying high-frequency power, these gases are ionized and plasma is formed. The high-frequency power supply 34 may be configured to supply high-frequency power at any of the following frequencies: 450 kHz, 13.56 MHz, 915 MHz, or 2.45 GHz. Furthermore, the high-frequency power supply 34 supplies high-frequency power greater than 0 W and less than or equal to 2000 W.

[0020] Furthermore, the high-frequency power supply 34 in this example is provided with a power supply control unit 35. The power supply control unit 35 has a function to control the on / off switching of high-frequency power at a preset period, and a function to control the application of high-frequency power to the parallel plates and the stopping of the application of said high-frequency power alternately while performing the on / off switching. The details of these high-frequency power control functions will be explained later with reference to Figure 4. The high-frequency power supply 34 and the power supply control unit 35 correspond to the high-frequency power supply unit in this embodiment.

[0021] Furthermore, the downstream end of the gas supply passage 40 is connected to the diffusion chamber 31 of the showerhead 3. Upstream of this gas supply passage 40, the TiCl4 gas supply pipe 41, which is a supply passage for TiCl4 gas, a titanium raw material gas, the Ar gas supply pipe 42, which is a supply passage for Ar gas added for plasma generation, and the H2 gas supply pipe 43, which is a supply passage for H2 gas, a reaction gas, converge.

[0022] A TiCl4 gas supply source 410 is connected to the upstream end of the TiCl4 gas supply pipe 41, and a flow rate control unit M41 and a valve V41 are installed in that order from upstream (raw material gas supply section). Similarly, an Ar gas supply source 420 is connected to the upstream end of the Ar gas supply pipe 42, and a flow rate control unit M42 and a valve V42 are installed in that order from upstream. Furthermore, an H2 gas supply source 430 is connected to the upstream end of the H2 gas supply pipe 43, and a flow rate control unit M43 and a valve V43 are installed in that order from upstream (reaction gas supply section). These mixed gases of TiCl4 gas, H2 gas, and Ar gas (hereinafter also referred to as "film-forming gas") flow into the diffusion chamber 31 of the showerhead 3 via the gas supply passage 40 and are supplied into the processing container 10 through the discharge hole 32.

[0023] The film deposition apparatus 1, having the configuration described above, includes a control unit 100 as shown in Figure 3. The control unit 100 is composed of a computer including a storage unit for storing a program, memory, and a CPU. The program is structured with instructions (steps) to execute the film deposition process of the Ti film 61 by outputting control signals from the control unit 100 to each part of the film deposition apparatus 1, thereby controlling the supply and disconnection of each gas and the supply of high-frequency power. The program is stored in the computer's storage unit, such as a flexible disk, compact disk, hard disk, MO (magneto-optical disk), or non-volatile memory, and is read from this storage unit and installed in the control unit 100.

[0024] Figure 4 is an example of a time chart related to the film deposition process performed using the film deposition apparatus 1 described above. This time chart schematically shows the timing of supplying and cutting off the film deposition gas to the processing container 10, and the timing of applying high-frequency power (labeled "RF" in Figure 4) from the high-frequency power supply 34. According to this time chart, the film-forming gas is supplied continuously at a predetermined flow rate for a specified period of time.

[0025] On the other hand, the high-frequency power supplied via the showerhead 3 (upper electrode) is applied to the space where the film-forming gas is supplied, but only at predetermined timings during the period in which the film-forming gas is supplied. In detail, periods of applying high-frequency power to plasmaize the film-forming gas containing TiCl4 gas and periods of stopping the application of said high-frequency power are alternately set. Furthermore, even during the periods when high-frequency power is applied, the high-frequency power is repeatedly switched "on" (application of high-frequency power) and "off" (stopping the application of high-frequency power) in short intervals.

[0026] The on / off period of the high frequency can be in the range of 40 microseconds to 100 milliseconds, for example, 100 microseconds. The percentage of time the high frequency is on during this period can be in the range of 20.0% to 99.9%, for example, 20% (on: 20 microseconds, off: 80 microseconds).

[0027] The period of the high-frequency power is 2.22 microseconds at 450 kHz, 73.7 nanoseconds at 13.56 MHz, 1.06 nanoseconds at 915 MHz, and 0.4 nanoseconds at 2.45 GHz. Therefore, during the "on" period, the high-frequency power is applied to the film deposition gas for a period sufficiently longer than each period, regardless of the frequency.

[0028] The periods during which high-frequency power is applied while repeatedly switching it on and off, and the periods during which the application of high-frequency power is stopped, are each set within a range of 2 seconds or more and 20 seconds or less. Here, we can illustrate the case where the period during which high-frequency power is applied is 5 seconds and the period during which it is stopped is 5 seconds.

[0029] As per the aforementioned time setting, multiple on / off cycles are performed during the period in which high-frequency power is applied. Note that Figure 4 schematically shows how the on / off of high-frequency power is performed and does not represent the actual number of on / off cycles. Furthermore, as per the above time setting, a period of suspension of high-frequency power application is ensured that is longer than one cycle of high-frequency power on / off. This makes it possible to clearly distinguish between the "off" time during the high-frequency power supply period and the period during which high-frequency power application is suspended. For example, when forming a Ti film 61 with a thickness of 10 nm within the range of 0.1 to 150 nm, the application and stopping of high-frequency power is performed for approximately 40 cycles within the range of 10 to 80 cycles.

[0030] The reason for repeatedly switching the high-frequency power on and off is to adjust the ionization of the deposition gas during plasma generation. of By not applying the solvent continuously, the formation of the highly reactive TiCl2 radical 7a is suppressed, while the formation of the less reactive TiCl3 radical 7b is promoted. Furthermore, the reason for setting a period during which the application of high-frequency power is stopped is to ensure that the non-ionized film-forming gas has time to enter the recess 50.

[0031] The supply and interruption of the film-forming gas and the timing of the application of high-frequency power are controlled by the control unit 100 and the power supply control unit 35, and the time chart shown in Figure 4 is executed. Specifically, the control unit 100 controls the opening and closing of valves V41, V42, and V43 to supply and cut off the gas supply, and also sets the flow rates of the flow rate adjustment units M41, M42, and M43. In addition, the control unit 100 sets the on / off cycle of the high frequency, the percentage of the on period, the period for applying high frequency power, and the period for stopping the high frequency power to the power supply control unit 35.

[0032] <Film formation method> The operation of the film deposition apparatus 1, which has the configuration described above, will now be explained. First, the gate valve 15 is opened, and the wafer W is loaded through the loading port 14 by a transport mechanism located in a vacuum transport chamber (not shown). The loaded wafer W is then transferred from the transport mechanism to the mounting table 2 via a lifting pin (not shown) and placed on the upper surface of the mounting table 2. Next, the transport mechanism is moved out of the processing container 10, and the gate valve 15 is closed. Then, the processing container 10 is evacuated by the vacuum exhaust unit 13, and the pressure inside the processing container 10 is adjusted to a preset pressure. The wafer W is also heated to 500°C by the heater 20 (substrate heating step).

[0033] Subsequently, at time T0 as shown in Figure 4, the supply of the film-forming gas is started (the process of supplying titanium raw material gas). After that, the system waits for a set time (e.g., 5 seconds) to elapse as the period during which the high-frequency power is not applied, and then at time T1, the application of high-frequency power is started. During the period of application of high-frequency power, the system repeatedly switches on and off as described above (e.g., on: 20 microseconds, off: 80 microseconds), and applies high-frequency power for a predetermined time (e.g., 5 seconds). Then, this application / stopping of high-frequency power is repeated for a predetermined cycle (e.g., 40 cycles). At this time, it is preferable to supply relatively low power from the power range (greater than 0W and 2000W or less) that can be supplied from the high-frequency power supply 34. A preferred example is the case where high-frequency power of 300W within the range of 100 to 500W is applied.

[0034] As a result of the above operation, the Ti film 61 is deposited in an atmosphere rich in mildly reactive TiCl3 radicals 7b, as schematically shown in Figure 2. The Ar gas contained in the deposition gas does not inhibit plasma formation, and unlike H2 gas, it has low reactivity with TiCl4 gas, thus exhibiting a dilution effect that moderates the reactivity of the deposition gas. These effects allow for the suppression of uneven film formation, such as the formation of the Ti film 61a concentrated near the opening of the recess 50, as described in the comparative configuration shown in Figure 1.

[0035] Furthermore, by providing a period during which the application of high-frequency power is stopped, time is ensured for the deposition gas before plasma formation to enter the recess 50. Subsequently, by applying high-frequency power, plasma is formed between the parallel plates (shower head 3 - mounting base 2), including the interior of the recess 50. This action allows TiCl3 radicals 7b to be supplied to the side walls and bottom surfaces located deep within the recess 50, and thus the Ti film 61 can be formed in these regions as well.

[0036] In this way, the application and cessation of high-frequency power is performed a predetermined number of times, and a Ti film 61 of a predetermined thickness is formed (step of forming the Ti film 61). Next, the application of high-frequency power is terminated, and the supply of the film-forming gas and heating of the wafer W are stopped. After that, the wafer W is removed from the processing container 10 in the reverse order of loading, and the process waits for the loading of the next wafer W.

[0037] In the Ti film 61 formed along the exposed surface of the silicon member 51, silicon atoms diffuse from the silicon member 51 side over time, eventually forming a titanium silicide (TiSi) film.

[0038] The embodiments described above have the following advantages. By providing a period during which the application of high-frequency power is stopped, time is secured for the film-forming gas to enter the recesses 50, and by repeatedly switching the high-frequency power on and off, a rich amount of mildly reactive TiCl3 radicals 7b are formed. As a result, a Ti film 61 with a uniform thickness can be formed in the recesses 50 formed on the wafer W with an aspect ratio of 25 or more.

[0039] <Other Embodiments> The object to which the Ti film 61 is formed using the film deposition apparatus 1 and high-frequency power application method described here with reference to Figures 3 and 4 is not limited to the configuration shown in Figure 2, in which a recess 50 is formed in the silicon member 51. For example, as shown in Figures 5(a) and (b), the recess 50 may be formed in a silicon oxide film (SiO film 52) covering the silicon member 51. In Figure 5, components common to those shown in Figures 1 and 2 are denoted by the same reference numerals as those shown in those figures. Although not explicitly stated in Figure 5, the aspect ratio of the recess 50 shown in this figure is 25 or greater.

[0040] Here, the TiCl4 gas also has the effect of etching titanium. On the other hand, compared to the silicon component 51, the SiO film 52 has a strong bond between silicon and oxygen, and its bond with the Ti film 61 formed on its surface is relatively weak. Therefore, The surface where the SiO film 52 is exposed is Etching by TiCl4 gas proceeds more easily on the surface where the silicon component 51 is exposed (the bottom surface of the recess 50 in the example shown in Figure 5).

[0041] In the recess 50 where the SiO film 52 is exposed, a film deposition process is performed based on the time chart explained using Figure 4. During the period when the high-frequency power is turned on (indicated as "RF On" in Figure 5(a)), titanium deposition by TiCl3 radicals 7b and the like progresses on the bottom surface (where the silicon member 51 is exposed) and the side walls (where the SiO film 52 is exposed) of the recess 50.

[0042] On the other hand, during the period when the high-frequency power is turned off (indicated as "RF off" in Figure 5(b)), TiCl4 molecules react with the deposited Ti at the sidewall surface where the bond with Ti is weak. As a result, new TiCl X A layer is formed, and etching of the Ti deposited on the surface of the SiO film 52 proceeds. Due to these effects, the Ti film 61b is hardly formed on the side wall surface of the recess 50, while the Ti film 61b can be formed only on the bottom surface of the recess 50 where the silicon member 51 is exposed.

[0043] Furthermore, the device on which the Ti film 61 is formed using the film deposition apparatus 1 and high-frequency power application method of this disclosure is not limited to power devices, but may also be a device for an integrated circuit. In this case as well, the technology of this disclosure is suitable when forming the Ti film 61 in a recess 50 with an aspect ratio of 25 or more. In the case of a device for an integrated circuit, the width dimension W of the recess 50 is in the range of 10.0 nm to 5.0 μm, and the depth dimension H Examples include cases where the depth is within the range of 0.25 to 125 μm. H The range is the minimum range in which the aspect ratio is 25 when the width dimension W is 10.0 nm to 5.0 μm, and deeper recesses 50 may be formed. The thickness of the TiN film 61 is, for example, in the range of 0.1 to 150 nm.

[0044] Furthermore, the recesses 50 on which the Ti film 61 is deposited using the method of this disclosure are not limited to those formed to extend in a vertical direction intersecting the surface of the wafer W, as illustrated in Figures 2 and 5(a) and (b). For example, longitudinal grooves may be formed on the surface of the wafer W, and a plurality of transverse grooves may be formed on the side walls of the longitudinal grooves, aligned in the thickness direction of the wafer W. These transverse grooves may be used as recesses, and the Ti film 61 may be deposited within these recesses. Furthermore, the member in which the recess 50 is formed is not limited to the silicon member 51, but may also be other metals or metal compounds.

[0045] In addition, the titanium raw material gas is not limited to the example of TiCl4 gas, but may be other gases containing titanium atoms. Other gases that may be used include organotitanium compounds such as TDMAT (tetrakisdimethylaminotitanium) and TDEAT (tetrakisdiethylaminotitanium). Furthermore, it is not a mandatory requirement to supply a reaction gas (H2 gas in the example described above) together with the titanium raw material gas. For example, a mixed gas of titanium raw material gas and Ar gas may be supplied into the processing container 10 as the film-forming gas. In this case as well, the film-forming gas can be plasma-generated by the high-frequency power applied by the method described above, and a Ti film 61 can be formed in the recess 50.

[0046] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Examples]

[0047] (Experiment 1) The Ti film 61 was formed in accordance with the embodiment described using Figures 2 to 4, and the formation status of the Ti film 61 within the recess 50 was confirmed. A. Experimental conditions Numerous circular recesses 50 with a width (diameter) W of 0.2 μm and a depth H of 10 μm (aspect ratio 50) were formed on the surface of a silicon wafer W. A Ti film 61 was deposited on this wafer W using a film deposition apparatus 1 as described in Figure 3, by applying high-frequency power according to the time chart described in Figure 4.

[0048] The supply flow rate of TiCl4 gas was 18 sccm, the supply flow rate of Ar gas was 1600 sccm, and the supply flow rate of H2 gas was 4000 sccm. The pressure inside the processing container 10 was set to 0.67 kPa (5 Torr), and the heating temperature of the wafer W was set to 500°C. Regarding the supply of high-frequency power, the on / off cycle of the high frequency was set to 100 microseconds (on: 20 microseconds, off: 80 microseconds), the period during which high-frequency power was applied was 5 seconds, and the period during which the application was stopped was 5 seconds. The application / stop of high-frequency power was performed for 40 cycles to deposit the Ti film 61.

[0049] B. Experimental Results Figure 6 shows electron microscope images of the wafer W after the deposition of the Ti film 61, specifically the area where the recess 50 is formed, magnified and captured using a Scanning Electron Microscope (SEM). Figure 6(a) is a photograph of the entire recess 50, while Figures 6(b) and (c) are magnified photographs of a portion of the top or bottom region of the recess 50. In Figures 6(a) to (c), the white areas formed along the side walls and bottom surfaces of the recess 50 correspond to the Ti film 61.

[0050] According to Figures 6(a) to 6(c), the formation of the Ti film 61 concentrated near the opening of the recess 50, as described using Figure 1, was not observed. Furthermore, it can be confirmed that a Ti film 61 of almost uniform thickness was formed from the top region to the bottom region of the recess 50. Therefore, the technology according to this disclosure can be evaluated as a suitable method for forming a uniform Ti film 61 in a recess 50 with an aspect ratio of 25 or more.

[0051] W wafer 1 Film deposition equipment 10 Processing containers 2. Mounting platform 34 High frequency power supply 410 TiCl4 gas supply source 61 Ti film

Claims

1. In a method for forming a titanium film in a recess formed on the surface of a substrate, A step of supplying titanium raw material gas, which is titanium tetrachloride gas, to a substrate in which a recess is formed, having an aspect ratio of 25 or more (the ratio of the depth dimension to the width dimension), silicon or silicon oxide exposed on the side wall surface, and silicon exposed on the bottom surface; A method comprising the steps of: during the period in which the step of supplying the titanium raw material gas is carried out, applying high-frequency power to the space to which the raw material gas is supplied while alternately switching it on and off to plasmaize the titanium raw material gas; and then stopping the application of the high-frequency power for a period longer than one cycle of switching the high-frequency power on and off; and repeating this process alternately multiple times to form the titanium film in the recess.

2. The method according to claim 1, wherein the width dimension of the recess is in the range of 10 nm to 5 μm.

3. The method according to claim 1 or 2, wherein the thickness of the titanium film is in the range of 0.1 to 150 nm.

4. The method according to any one of claims 1 to 3, wherein the on / off period of the high-frequency power is within the range of 40 microseconds to 100 milliseconds.

5. The method according to any one of claims 1 to 4, wherein in the step of supplying the titanium raw material gas, a reaction gas that reacts with the titanium raw material gas to form the titanium film is supplied in parallel.

6. The method according to claim 5, wherein the titanium raw material gas is titanium tetrachloride gas and the reaction gas is hydrogen gas.

7. The method according to any one of claims 1 to 6, wherein the period for applying the high-frequency power and the period for stopping the application of the high-frequency power are each set within a range of 2 seconds or more and 20 seconds or less.

8. The method according to any one of claims 1 to 7, comprising the step of heating the substrate to a temperature in the range of 400 to 800°C during the period in which the step of supplying the titanium raw material gas is being carried out.

9. The method according to any one of claims 1 to 8, wherein the aforementioned high-frequency power is a value greater than 0W and within the range of 2000W or less.

10. The method according to any one of claims 1 to 9, wherein the titanium film is formed along the surface where silicon is exposed, and after the formation of the titanium film, it becomes a titanium silicide film by the diffusion of silicon atoms.

11. The method according to claim 10, wherein the surface on which the silicon is exposed is the side wall surface and the bottom surface of the recess.

12. The method according to claim 10, wherein the surface on which the silicon is exposed is the bottom surface of the recess, silicon oxide is exposed on the side wall surface of the recess, and the titanium film is not formed on the side wall surface.

13. An apparatus for forming a titanium film in a recess formed on the surface of a substrate, A processing container for housing a substrate having an aspect ratio of 25 or more, where silicon or silicon oxide is exposed on the side wall surface, and the recess is formed on the bottom surface where silicon is exposed, A raw material gas supply unit that supplies titanium raw material gas, which is titanium tetrachloride gas, to the processing container, A high-frequency power supply unit for applying high-frequency power to the space inside the processing container from which the titanium raw material gas is supplied from the raw material gas supply unit, It comprises a control unit and, The control unit is configured to output a control signal for performing the steps of supplying a titanium raw material gas to the substrate in the processing container, applying high-frequency power to the space supplied with the raw material gas while alternately switching it on and off during the period in which the titanium raw material gas supply step is being performed, thereby plasmaizing the titanium raw material gas, and then stopping the application of the high-frequency power for a period longer than one cycle of switching the high-frequency power on and off, and repeating these steps alternately multiple times to form the titanium film in the recess.

14. The apparatus according to claim 13, wherein the control unit outputs the control signal such that the on / off period of the high-frequency power is within the range of 40 microseconds to 100 milliseconds.

15. The system further includes a reaction gas supply unit that supplies a reaction gas to the processing container, which reacts with a titanium raw material gas to form the titanium film. The apparatus according to claim 13 or 14, wherein the control unit outputs the control signal so that the supply of the reaction gas is carried out in parallel with the step of supplying the titanium raw material gas.

16. The apparatus according to claim 15, wherein the titanium raw material gas is titanium tetrachloride gas and the reaction gas is hydrogen gas.

17. The apparatus according to any one of claims 13 to 16, wherein the control unit outputs the control signal such that the period for applying the high-frequency power and the period for stopping the application of the high-frequency power are each within the range of 2 seconds or more and 20 seconds or less.

18. The processing container includes a heating unit for heating the substrate housed within it, The apparatus according to any one of claims 13 to 17, wherein the control unit outputs a control signal for performing a step of heating the substrate to a temperature in the range of 400 to 800°C during the period in which the step of supplying the titanium raw material gas is being performed.

19. The apparatus according to any one of claims 13 to 18, wherein the control unit outputs the control signal so that a high-frequency power value greater than 0W and less than or equal to 2000W is supplied.

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