JP2016098406A - Film deposition method of molybdenum film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method of a molybdenum film capable of depositing a practical molybdenum film by a CVD method or an ALD method by using a molybdenum raw material not containing fluorine.SOLUTION: MoClgas and reducing gas which are molybdenum raw materials are supplied simultaneously or alternately by sandwiching purge in a treatment vessel, into the treatment vessel having a reduced pressure atmosphere in which a substrate to be treated is arranged, and, while heating the substrate to be treated, MoClgas and reducing gas are reacted together on the substrate to be treated, to thereby deposit a molybdenum film.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for forming a molybdenum film.

  In a semiconductor manufacturing process, tungsten is used as a material for embedding contact holes and via holes between wirings formed on a semiconductor wafer (hereinafter simply referred to as a wafer) as an object to be processed, and as a material for the interdiffusion barrier. It is used. In addition, molybdenum, which is a high melting point metal similar to tungsten and can be expected to have a further lower resistance, is also being considered for application to similar applications.

  Tungsten and molybdenum can be easily formed by a physical vapor deposition (PVD) method such as sputtering, but it is difficult for the PVD method to cope with the high step coverage required for recent device miniaturization.

For this reason, the tungsten film has been formed by a chemical vapor deposition (CVD) method that can sufficiently cope with the miniaturization of the device, and tungsten hexafluoride (WF ₆ ), for example, is used as a source gas. A film forming method using H ₂ gas which is a reducing gas is known. In recent years, a tungsten film is also formed by an atomic layer deposition (ALD) method in which a WF ₆ gas and a reducing gas are alternately supplied as a technique for obtaining higher step coverage. On the other hand, miniaturization of design rules has been progressing in recent years, and when such a raw material containing fluorine is used, there is a concern that fluorine may adversely affect the device. W-based film forming raw materials that do not contain hydrogen have been studied. However, there is no example of mass production of tungsten films using these fluorine-containing film-forming raw materials, and WF ₆ continues to be used as a film-forming raw material for tungsten films under various circumstances. ing.

Although there have been few studies on the formation of a molybdenum film by a CVD method, Patent Document 1 discloses that a molybdenum film is formed by a CVD method using MoF ₆ or MoCl ₆ .

JP-A-7-238379

However, Patent Document 1 only shows MoF ₆ and MoCl ₆ as a part of the source gas for forming various metal films by the CVD method, and actually uses MoF ₆ or MoCl _6. An example in which a molybdenum film is formed is not described.

  When a molybdenum film is used as a buried metal for a fine contact hole or via hole, like a tungsten film, it must be a practical film having good embeddability and good film quality, and no adverse effects on the device. However, conventionally, it has not been studied to form a molybdenum film by the CVD method in consideration of such points.

  Therefore, an object of the present invention is to provide a method for forming a molybdenum film, which can form a practical molybdenum film by a CVD method or an ALD method using a molybdenum raw material not containing fluorine.

As described above, the use of a molybdenum film formed by CVD or ALD as an embedded metal has not been studied, but the present inventors have currently used a tungsten film as a film forming raw material for molybdenum containing no fluorine. Attention was focused on molybdenum chloride (such as MoCl ₅ ), which is a halide similar to WF ₆ that is frequently used as a raw material for the above.

  As a result, it was found that by appropriately setting conditions, a practical molybdenum film having good embedding property and good film quality can be obtained by CVD or ALD.

  That is, according to the present invention, molybdenum chloride gas and reducing gas as molybdenum raw materials are alternately supplied to a processing container in a reduced-pressure atmosphere in which a substrate to be processed is disposed, simultaneously or with a purge in the processing container interposed therebetween, A method for forming a molybdenum film is provided, in which a molybdenum film is formed by reacting a molybdenum chloride gas and a reducing gas on a substrate to be processed while heating the substrate.

In the above structure, it is preferable that the temperature of the substrate to be processed and the pressure in the processing container be such that the underlying layer of the molybdenum film to be formed is not etched by molybdenum chloride. As the molybdenum chloride, MoCl ₅ can be suitably used.

  The substrate to be processed preferably has a TiN film or a TiSiN film as a base for the molybdenum film.

  Furthermore, it is preferable that high-temperature and high-temperature conditions are such that the temperature of the substrate to be processed is 400 ° C. or higher and the pressure in the processing container is 5 Torr (667 Pa) or higher. More preferably, the temperature of the substrate to be processed is 450 ° C. or higher, and the pressure in the processing container is 10 Torr (1333 Pa) or higher.

As the reducing gas, it is preferable to use at least one selected from H ₂ gas, SiH ₄ gas, B ₂ H ₆ gas, and NH ₃ gas. Moreover, it is preferable to first perform initial film formation using SiH ₄ gas or B ₂ H ₆ gas as the reducing gas, and then perform main film formation using H ₂ gas as the reducing gas.

  Further, the present invention is a storage medium that operates on a computer and stores a program for controlling a film forming apparatus, and the program performs the molybdenum film forming method when executed. A storage medium is provided that causes a computer to control the film formation apparatus.

  According to the present invention, by using molybdenum chloride as a molybdenum raw material not containing fluorine, a practical molybdenum film having good embedding property and good characteristics can be obtained by CVD or ALD.

It is sectional drawing which shows an example of the film-forming apparatus for enforcing the film-forming method of the molybdenum film | membrane which concerns on this invention. It is a figure which shows the process recipe in the case of the film-forming by CVD method. It is a figure which shows the process recipe in the case of the film-forming by ALD method. It is a figure which shows the relationship between the wafer temperature at the time of forming a molybdenum film | membrane by ALD method on the TiN film | membrane which is a base film, and the film-forming rate per cycle. It is a figure which shows the relationship between a wafer temperature at the time of forming a molybdenum film | membrane by ALD method on the TiN film | membrane which is a base film. It is a figure which shows the X-ray-diffraction spectrum of the molybdenum film | membrane formed into a film by ALD method on the TiN film | membrane which is a base film. It is a SEM photograph of a section at the time of forming a molybdenum film in a hole of aspect ratio 60.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

<Deposition system>
FIG. 1 is a sectional view showing an example of a film forming apparatus for carrying out the method for forming a molybdenum film according to the present invention.

  As shown in FIG. 1, a film forming apparatus 100 has a substantially cylindrical chamber 1 that is airtight, and a susceptor 2 for horizontally supporting a wafer W that is a substrate to be processed. However, it arrange | positions in the state supported by the cylindrical support member 3 which reaches the center lower part from the bottom part of the exhaust chamber mentioned later. The susceptor 2 is made of ceramics such as AlN. Further, a heater 5 is embedded in the susceptor 2, and a heater power source 6 is connected to the heater 5. On the other hand, a thermocouple 7 is provided in the vicinity of the upper surface of the susceptor 2, and a signal of the thermocouple 7 is transmitted to the heater controller 8. The heater controller 8 transmits a command to the heater power supply 6 in accordance with a signal from the thermocouple 7, and controls the heating of the heater 5 to control the wafer W to a predetermined temperature. The susceptor 2 is provided with three wafer raising / lowering pins (not shown) so as to be able to project and retract with respect to the surface of the susceptor 2, and is projected from the surface of the susceptor 2 when the wafer W is transferred. To be. The susceptor 2 can be lifted and lowered by a lifting mechanism (not shown).

A circular hole 1 b is formed in the top wall 1 a of the chamber 1, and a shower head 10 is fitted so as to protrude into the chamber 1 therefrom. The shower head 10 is for discharging a MoCl ₅ gas, which is a film forming raw material gas supplied from a gas supply mechanism 30 described later, into the chamber 1, and an N ₂ gas as a MoCl ₅ gas and a purge gas is disposed above the shower head 10. a first introduction passage 11 for introducing a gas, and a second introduction path 12 for introducing the N ₂ gas as H ₂ gas and purge gas as the reducing gas.

Inside the shower head 10, spaces 13 and 14 are provided in two upper and lower stages. A first introduction path 11 is connected to the upper space 13, and a first gas discharge path 15 extends from the space 13 to the bottom surface of the shower head 10. A second introduction path 12 is connected to the lower space 14, and a second gas discharge path 16 extends from the space 14 to the bottom surface of the shower head 10. That is, the shower head 10 is configured so that MoCl ₅ gas as a film forming source gas and H ₂ gas as a reducing gas are independently discharged from the discharge passages 15 and 16.

  An exhaust chamber 21 that protrudes downward is provided on the bottom wall of the chamber 1. An exhaust pipe 22 is connected to the side surface of the exhaust chamber 21, and an exhaust device 23 having a vacuum pump, a pressure control valve, and the like is connected to the exhaust pipe 22. By operating the exhaust device 23, the inside of the chamber 1 can be brought into a predetermined reduced pressure state.

  On the side wall of the chamber 1, a loading / unloading port 24 for loading / unloading the wafer W and a gate valve 25 for opening / closing the loading / unloading port 24 are provided. A heater 26 is provided on the wall portion of the chamber 1 so that the temperature of the inner wall of the chamber 1 can be controlled during the film forming process.

The gas supply mechanism 30 has a film forming raw material tank 31 that stores MoCl ₅ as a film forming raw material. MoCl ₅ is a solid at ambient temperature, the inside film forming material tank 31 is MoCl ₅ is molybdenum chloride as molybdenum raw material is accommodated as a solid. A heater 31a is provided around the film forming raw material tank 31, and the film forming raw material in the tank 31 is heated to an appropriate temperature (for example, 70 to 150 ° C.) to sublimate MoCl ₅ . . MoCl ₆ can also be used as molybdenum chloride. Even when MoCl ₆ is used, the same behavior as MoCl ₅ is exhibited.

A carrier gas pipe 32 for supplying N ₂ gas which is a carrier gas from above is inserted into the film forming material tank 31. An N ₂ gas supply source 33 is connected to the carrier gas pipe 32. Further, the carrier gas pipe 32 is provided with a mass flow controller 34 as a flow rate controller and front and rear valves 35. Further, a raw material gas delivery pipe 36 serving as a raw material gas line is inserted into the film forming raw material tank 31 from above, and the other end of the raw material gas delivery pipe 36 is connected to the first introduction path 11 of the shower head 10. Has been. A valve 37 is interposed in the source gas delivery pipe 36. The source gas delivery pipe 36 is provided with a heater 38 for preventing condensation of MoCl ₅ gas, which is a film forming source gas. Then, the MoCl ₅ gas sublimated in the film forming raw material tank 31 is transferred from the (carrier N ₂ ) to the N ₂ gas as the carrier gas, and the shower head is passed through the raw material gas delivery pipe 36 and the first introduction path 11. 10 is supplied. Further, the raw material gas delivery pipe 36, _{N 2} gas supply source 71 is connected for supplying the _{N 2} gas as a purge gas through a pipe 74 (the purge _{N 2).} A mass flow controller 72 as a flow rate controller and a valve 73 before and after the mass flow controller 72 are interposed in the pipe 74.

The carrier gas pipe 32 and the source gas delivery pipe 36 are connected by a bypass pipe 48, and a valve 49 is interposed in the bypass pipe 48. Valves 35a and 37a are interposed on the downstream side of the pipe 48 connection portion in the carrier gas pipe 32 and the raw material gas delivery pipe 36, respectively. Then, by opening the valve 49 closes the valve 35a, the 37a, the _{N 2} gas from the _{N 2} gas supply source 33, a carrier gas pipe 32, through the bypass pipe 48, it is possible to purge the feed gas delivery pipe 36 It has become. The carrier gas and the purge gas are not limited to N ₂ gas but may be other inert gas such as Ar gas.

The second inlet channel 12 of the shower head 10 is connected a pipe 40 which is a H ₂ gas line, the pipe 40 includes a H ₂ gas supply source 42 for supplying H ₂ gas as a reducing gas, _{N 2} gas supply source 61 for supplying _{N 2} gas (purge _{N 2)} as purge gas via the pipe 64 is connected. The pipe 40 is provided with a mass flow controller 44 as a flow rate controller and its front and rear valves 45, and the pipe 64 is provided with a mass flow controller 62 as a flow rate controller and its front and rear valves 63. The reducing gas is not limited to H ₂ gas, and SiH ₄ gas, B ₂ H ₆ gas, and NH ₃ gas can also be used. Two or more of H ₂ gas, SiH ₄ gas, B ₂ H ₆ gas, and NH ₃ gas may be supplied. In addition, other reducing gases such as PH ₃ gas and SiH ₂ Cl ₂ gas may be used.

  The film forming apparatus 100 includes a control unit 50 that controls each component, specifically, a valve, a power source, a heater, a pump, and the like. The control unit 50 includes a process controller 51 including a microprocessor (computer), a user interface 52, and a storage unit 53. Each component of the film forming apparatus 100 is electrically connected to the process controller 51 and controlled. The user interface 52 is connected to the process controller 51, and a keyboard on which an operator inputs a command to manage each component of the film forming apparatus 100 and the operating status of each component of the film forming device. It consists of a display that visualizes and displays it. The storage unit 53 is also connected to the process controller 51, and the storage unit 53 corresponds to a control program for realizing various processes executed by the film forming apparatus 100 under the control of the process controller 51 and processing conditions. A control program for causing each component of the film forming apparatus 100 to execute a predetermined process, that is, a process recipe, various databases, and the like are stored. The processing recipe is stored in a storage medium (not shown) in the storage unit 53. The storage medium may be a fixed medium such as a hard disk or a portable medium such as a CDROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example.

  Then, if necessary, a predetermined processing recipe is called from the storage unit 53 by an instruction from the user interface 52 and executed by the process controller 51, so that the film forming apparatus 100 can control the process controller 51. Desired processing is performed.

<Embodiment of Film Formation Method>
Next, an embodiment of a film forming method performed using the film forming apparatus 100 configured as described above will be described.

  First, the gate valve 25 is opened, a wafer W is loaded into the chamber 1 via the loading / unloading port 24 by a transfer device (not shown), and placed on the susceptor 2 heated to a predetermined temperature by the heater 5. After the pressure is reduced to a degree of vacuum, a molybdenum film is formed by CVD or ALD as follows. As the wafer W, for example, a wafer in which a barrier metal film (for example, a TiN film or a TiSiN film) is formed as a base film on the surface of a thermal oxide film or an interlayer insulating film having a recess such as a trench or a hole is used. it can. Molybdenum film has poor adhesion to the thermal oxide film and interlayer insulating film, and the incubation time is long, so it is difficult to form the film on the thermal oxide film and interlayer insulating film. By using it as a base film, film formation becomes easy. However, the base film is not limited to this.

(Film formation by CVD method)
First, film formation by the CVD method will be described.
FIG. 2 is a diagram showing a processing recipe at the time of film formation by the CVD method. First, the valves 37, 37 a and 45 are closed and the valves 63 and 73 are opened, and N ₂ gas (purge N ₂ ) as purge gas is supplied from the N ₂ gas supply sources 61 and 71 through the pipes 64 and 74 into the chamber 1. To increase the pressure to stabilize the temperature of the wafer W on the susceptor 2.

After the inside of the chamber 1 reaches a predetermined pressure, the valves 37 and 37a are opened while the purge N ₂ from the N ₂ gas supply sources 61 and 71 is allowed to flow, so that N ₂ gas as a carrier gas (carrier N ₂ ) Is supplied into the film forming raw material tank 31, and MoCl ₅ is sublimated in the film forming raw material tank 31, and the generated MoCl ₅ gas is supplied into the chamber 1, and the valve 45 is opened to open the H ₂ gas supply source 42. H ₂ gas is supplied into the chamber 1. As a result, a reaction between MoCl ₅ gas, which is a molybdenum source gas, and H ₂ gas, which is a reducing gas, occurs on the underlying film on the surface of the wafer W, and a molybdenum film is formed. The same applies when MoCl ₆ gas is used as the molybdenum source gas.

After the film formation is continued until the film thickness of the molybdenum film reaches a predetermined value, the valve 45 is closed to stop the supply of H ₂ gas, and the valves 37 and 37a are further closed to stop the MoCl ₅ gas and purge. Only N ₂ is supplied into the chamber 1 to purge the chamber 1. Thus, the film formation by the CVD method is completed. The film thickness of the molybdenum film at this time can be controlled by the film formation time.

(Deposition by ALD method)
Next, film formation by the ALD method will be described.
FIG. 3 is a diagram showing a processing recipe at the time of film formation by the ALD method. First, as in the case of the CVD method, the valves 37, 37a and 45 are closed and the valves 63 and 73 are opened. From the N ₂ gas supply sources 61 and 71 through the pipes 64 and 74, N ₂ gas (purge N ₂ ) is supplied into the chamber 1 to increase the pressure to stabilize the temperature of the wafer W on the susceptor 2.

After the inside of the chamber 1 reaches a predetermined pressure, the purge N ₂ is flown from the N ₂ gas supply source 61 through the pipe 64 and the valve 73 is closed to stop the purge N ₂ on the pipe 74 side. By opening 37a, the carrier N ₂ is supplied from the N ₂ gas supply source 33 into the film forming raw material tank 31, and the MoCl ₅ gas sublimated in the film forming raw material tank 31 is supplied into the chamber 1 for a short time. MoCl ₅ is adsorbed onto the underlying film formed on the W surface (MoCl ₅ gas supply step), then the valves 37 and 37a are closed, the valve 73 is opened, the MoCl ₅ gas is stopped, and the pipe 64 is purged N _In addition to ₂ , purge N ₂ from the pipe 74 side is also supplied into the chamber 1 to purge excess MoCl ₅ gas in the chamber 1 (purge step).

Next, with the purge N ₂ gas flowing from the N ₂ gas supply source 71 via the pipe 74, the valve 63 is closed to stop the purge N ₂ on the pipe 64 side, and the valve 45 is opened to open the H ₂ gas supply source 42. Then, H ₂ gas is supplied into the chamber 1 for a short time to react with MoCl ₅ adsorbed on the wafer W (H ₂ gas supply step), then the valve 45 is closed and the valve 63 is opened to supply the H ₂ gas. purge N ₂ from the pipe 64 side in addition to the purge N ₂ of the pipe 74 is stopped also supplied into the chamber 1 to purge excess H ₂ gas in the chamber 1 (purge step).

A thin molybdenum unit film is formed by one cycle of the above MoCl ₅ gas supply step, purge step, H ₂ gas supply step, and purge step. Then, a molybdenum film having a desired film thickness is formed by repeating these steps for a plurality of cycles. The film thickness of the molybdenum film at this time can be controlled by the number of repetitions of the above cycle. The same applies when MoCl ₆ gas is used as the molybdenum source gas.

(Deposition conditions)
When MoCl ₅ that is molybdenum chloride is used as the molybdenum raw material, the MoCl ₅ gas itself also has an etching action. Therefore, depending on the temperature and pressure conditions, the base of the molybdenum film is etched with the MoCl ₅ gas, so that the molybdenum film is formed. It may be difficult to form a film. Therefore, it is preferable that the temperature and pressure conditions are other than the conditions that cause such an etching reaction. More specifically, since a film formation reaction or an etching reaction does not occur in a region where the temperature is low, a high temperature is preferable for causing the film formation reaction. However, at a high temperature at which the film formation reaction occurs, an etching reaction occurs when the pressure is low. Tend to occur. Therefore, high temperature and high pressure conditions are preferred. The same applies when MoCl ₆ is used as molybdenum chloride.

  Specifically, although depending on the type of the underlying film, it is preferable that both the CVD method and the ALD method have a wafer temperature (susceptor surface temperature) of 400 ° C. or higher and a chamber pressure of 5 Torr (667 Pa) or higher. This is because if the wafer temperature is lower than 400 ° C., the film forming reaction is difficult to occur, and if the pressure is lower than 5 Torr, the etching reaction is likely to occur at 400 ° C. or higher. In addition, when the wafer temperature is 400 ° C., the amount of film formation tends to decrease at 5 Torr. However, since a sufficient amount of film formation can be obtained at 10 Torr (1333 Pa), the pressure in the chamber should be 10 Torr or more. preferable. The wafer temperature is more preferably 450 ° C. or higher.

  From the standpoint of obtaining a sufficient amount of film formation, there is no upper limit to the temperature, but the upper limit is about 800 ° C. from the viewpoint of apparatus limitations and reactivity. A more preferable range of the wafer temperature is 400 to 700 ° C, more preferably 400 to 650 ° C, and still more preferably 450 to 650 ° C. Moreover, although there is no upper limit in terms of pressure from the above point, the upper limit is 100 Torr (13333 Pa) in the same manner from the viewpoint of apparatus limitations and reactivity. More preferably, it is 10 to 40 Torr (1333 to 533 Pa). Note that the preferred range of temperature and pressure conditions varies somewhat depending on the structure of the actual apparatus and other conditions.

Preferred ranges for other conditions are as follows.
CVD method Carrier N ₂ gas flow rate: 20 to 1000 sccm (mL / min)
(MoCl ₅ gas supply amount is 0.5 to 25 sccm (mL / min))
H ₂ gas flow rate: 500 to 5000 sccm (mL / min)
Heating temperature of film forming raw material tank: 70 to 150 ° C.
ALD method Carrier N ₂ gas flow rate: 20 to 500 sccm (mL / min)
(MoCl ₅ gas supply amount is 0.5 to 12.5 sccm (mL / min))
MoCl ₅ gas supply time (per time): 0.05 to 10 sec
H ₂ gas flow rate: 500 to 5000 sccm (mL / min)
H ₂ gas supply time: (per time): 0.1 to 10 sec
Heating temperature of film forming raw material tank: 70 to 150 ° C.

In both the CVD method and the ALD method, SiH ₄ gas, B ₂ H ₆ gas, and NH ₃ gas can be used as the reducing gas, in addition to H ₂ gas. A preferable film formation can be performed under certain conditions. From the viewpoint of further reducing impurities in the film, it is preferable to use H ₂ gas. Further, by using NH ₃ gas, good reactivity can be obtained, and the film formation rate can be increased. Also, as described above, other reducing gases such as PH ₃ gas and SiH ₂ Cl ₂ gas can be used.

(Effects of the embodiment, etc.)
By the film formation method as described above, a practical molybdenum film having good embedding property and good film quality can be formed. Specifically, a molybdenum film with low impurity concentration such as Cl, C, N, and O and low specific resistance can be obtained. In addition, a molybdenum film with good step coverage can be obtained.

<Other Embodiments of Film Formation Method>
Next, another embodiment of the film forming method will be described.
In this embodiment, after forming an initial molybdenum film by a CVD method or an ALD method on a barrier metal film (TiN film or TiSiN film) formed as a base film on a thermal oxide film or an interlayer insulating film, the same Then, a main molybdenum film is formed by CVD or ALD. In this manner, by forming the main molybdenum film on the initial molybdenum film, the conditions under which the main molybdenum film can be formed can be expanded. The film thickness of the initial molybdenum film is preferably 3 to 10 nm.

In this case, it is preferable to use SiH ₄ gas or B ₂ H ₆ gas as the reducing gas when forming the initial molybdenum film, and H ₂ gas as the reducing gas when forming the main molybdenum film. By doing so, it is possible to obtain a molybdenum film having a lower resistance than that in which a molybdenum film is directly formed on the base film by H ₂ reduction without substantially increasing impurities. This is considered to be because the size of the molybdenum crystal particles is increased by forming the main molybdenum film on the initial molybdenum film formed using SiH ₄ gas or B ₂ H ₆ gas as the reducing gas. .

<Experimental example>
Next, experimental examples will be described.
(Experimental example 1)
Here, a TiN film is used as the base film, the wafer temperature (susceptor surface temperature) is changed at four levels of 400 ° C., 450 ° C., 500 ° C., and 550 ° C., and the chamber pressure is 30 Torr. Then, a molybdenum film was formed by ALD method. Other conditions include carrier N ₂ gas flow rate: 150 sccm, H ₂ gas flow rate: 2000 sccm, MoCl ₅ supply step time: 1.5 sec, H ₂ gas supply step time: 3 sec, purge step once Time: 5 sec.

  FIG. 4 shows the relationship between the wafer temperature at this time and the film formation rate per cycle. As shown in FIG. 4, the film formation rate tended to increase as the wafer temperature increased. The highest film formation rate of 0.035 nm / cycle was obtained at 550 ° C., the highest temperature and high pressure within the range of this experiment. In this experimental example, the film was not formed at 400 ° C., but it was confirmed that the film was formed at 400 ° C. by appropriately adjusting other conditions.

  Next, the specific resistance at 20 nm was measured for the molybdenum film formed at 450 ° C., 500 ° C., and 550 ° C. as described above. The result is shown in FIG. As shown in FIG. 5, the specific resistance is 25 μΩ · cm at 450 ° C., 30 μΩ · cm at 500 ° C., and 38 μΩ · cm at 550 ° C., both of which are practical levels. It was confirmed that a film was obtained.

  Further, the crystal structure of the molybdenum film formed at 450 ° C. was identified by X-ray diffraction (XRD). The X-ray diffraction spectrum of the film at that time is shown in FIG. It was confirmed that the film obtained from FIG. 6 was pure molybdenum.

(Experimental example 2)
In Experimental Example 2, the step coverage of the molybdenum film was confirmed. A TiN film was formed as a base film in a hole having a top diameter of 0.18 μm and an aspect ratio of 60, and a molybdenum film was formed by ALD using the film forming apparatus of FIG. The conditions at this time are as follows: wafer temperature: 540 ° C., chamber internal pressure: 30 Torr, carrier N ₂ gas flow rate: 500 sccm, H ₂ gas flow rate: 2000 sccm, MoCl ₅ supply step time: 1.5 sec, H ₂ gas supply Time for one step: 3 sec, time for one purge step: 5 sec, number of cycles: 600 times.

  The SEM photograph of the cross section at this time is shown in FIG. As shown in FIG. 7, it was confirmed that the molybdenum film was formed to the bottom of the hole having a top diameter of 0.18 μm and an aspect ratio of 60, and the step coverage was sufficiently high as 67%.

<Other applications>
As mentioned above, although embodiment of this invention was described, this invention can be variously deformed, without being limited to the said embodiment. For example, in the above embodiment, the semiconductor wafer is described as an example of the substrate to be processed. However, the semiconductor wafer may be silicon or a compound semiconductor such as GaAs, SiC, or GaN, and is not limited to the semiconductor wafer. The present invention can also be applied to a glass substrate, a ceramic substrate, or the like used for an FPD (flat panel display) such as a liquid crystal display device.

1; chamber 2; susceptor 5; heater 10, showerhead to 30; the gas supply mechanism 31; film forming material tank 42; _{H 2} gas supply source 50; the control unit 51; the process controller 53; storage unit 61 and 71; _{N 2} gas Supply source W; semiconductor wafer

Claims (10)

  Molybdenum chloride gas and reducing gas as molybdenum raw materials are supplied alternately or alternately with a purge inside the processing container in a processing container in a reduced pressure atmosphere where the processing target substrate is arranged, and the processing target substrate is heated while being processed. A method for forming a molybdenum film, comprising reacting molybdenum chloride gas and a reducing gas on a substrate to form a molybdenum film.   2. The method of forming a molybdenum film according to claim 1, wherein the temperature of the substrate to be processed and the pressure in the processing container are such that the molybdenum film substrate to be formed is not etched by molybdenum chloride. The method for forming a molybdenum film according to claim 1, wherein the molybdenum chloride is MoCl ₅ .   4. The method of forming a molybdenum film according to claim 1, wherein the substrate to be processed includes a TiN film or a TiSiN film as a base of the molybdenum film. 5.   5. The method for forming a molybdenum film according to claim 1, wherein the temperature of the substrate to be processed is 400 ° C. or more and the pressure in the processing container is 5 Torr or more.   The method for forming a molybdenum film according to claim 5, wherein the temperature of the substrate to be processed is 450 ° C. or higher.   6. The method for forming a molybdenum film according to claim 5, wherein the pressure in the processing container is 10 Torr or more. 8. The reducing gas according to claim 1, wherein the reducing gas is at least one selected from H ₂ gas, SiH ₄ gas, B ₂ H ₆ gas, and NH ₃ gas. Of forming a molybdenum film. The initial film formation is performed using SiH ₄ gas or B ₂ H ₆ gas as the reducing gas, and then the main film formation is performed using H ₂ gas as the reducing gas. 8. The method for forming a molybdenum film according to any one of 7 above. A storage medium that operates on a computer and stores a program for controlling the film forming apparatus,
A storage medium that, when executed, causes a computer to control the film formation apparatus so that the molybdenum film formation method according to any one of claims 1 to 9 is performed.