JP2019039022A - Film deposition apparatus and gas supply mechanism - Google Patents

Abstract

To suppress foreign matter made of carbon from being mixed with a metal film in depositing the metal film on a substrate.SOLUTION: An apparatus is constituted which comprises: a film deposition raw material storage part 31 which stores a film deposition raw material, or metal chloride; a raw material gas supply path 21 for supplying a vaporized film deposition raw material to a processing container 11 so as to deposit a metal film, composed of metal constituting metal chloride, on a substrate B; a carrier supply part 25 for supplying a carrier gas to the film deposition raw material storage part 31 and introducing the vaporized film deposition raw material into the raw material gas supply path 21 together with the carrier gas; and a mixed suppression gas supply part 26 which supplies a mixed suppression gas for foreign matter for suppressing deposition of foreign matter composed of carbon from the film deposition raw material or for suppressing the foreign matter from being mixed in the metal film by vaporizing the foreign matter to the film deposition raw material storage part 31 or to the raw material gas supply path 21 so that the mixed suppress gas is mixed with the vaporized film deposition raw material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film forming apparatus and a gas supply mechanism for forming a metal film on a substrate.

In a semiconductor device manufacturing process, a metal chloride is supplied as a film forming raw material to a semiconductor wafer (hereinafter referred to as “wafer”), which is a substrate, and a film made of a metal constituting the metal chloride is formed. May be performed. In Patent Document 1, as this metal chloride, WCl ₆ (tungsten hexachloride) which is a solid is vaporized, supplied to a wafer in a processing container together with a carrier gas, and further supplied with a reducing gas, W (tungsten). ) A film forming apparatus for forming a film is described.

Japanese Patent Laid-Open No. 2006-84517

In forming the W film, it has been studied to use WCl ₅ (tungsten pentachloride) instead of WCl ₆ as a film forming material. However, when WCl ₆ is used as a film forming raw material, the amount of carbon particles as foreign substances contained in the W film may increase as compared with the case where WCl ₅ is used as a film forming raw material. confirmed. The particles mixed in the film when using WCl ₅ as described above are used in the manufacturing process of WCl ₅ which is a film forming raw material, and are generated from a carbon compound such as an organic solvent remaining in the film forming raw material. it is conceivable that.

In order to suppress the mixing of particles into the W film, adjustment is made so that the valve for supplying the purge gas for purging the inside of the processing container and each pipe constituting the film forming apparatus is opened and closed at an appropriate timing. Therefore, it is possible to take measures to adjust the temperature of the wafer during the film formation process to be appropriate. In addition, the particles adhere to the piping system of the film forming apparatus. Of the valves provided in the piping system, a valve in which a relatively large amount of the particles accumulates is always opened to easily discharge the particles from the apparatus. It is possible to take measures to prevent the particles from entering the film as an environment. However, even if these measures are taken, it is insufficient to suppress the mixing of particles into the film, and a technique capable of further reducing the amount of particles mixed into the film is required.

  The present invention has been made based on such circumstances, and its purpose is to form a metal film on a substrate using a film forming material made of metal chloride, and the metal film is made of carbon. It is providing the technique which can suppress that a foreign material mixes.

The film forming apparatus of the present invention includes a processing container for storing a substrate,
A film forming raw material reservoir for storing a film forming raw material that is a solid or liquid metal chloride;
A raw material gas supply path for supplying the vaporized film forming raw material to the processing vessel in order to form a metal film composed of a metal constituting the metal chloride on the substrate;
A carrier gas supply unit configured to supply a carrier gas to the film forming material storage unit and introduce the film forming material vaporized together with the carrier gas into the source gas supply path;
A foreign matter mixing suppression gas for suppressing the precipitation of foreign matter composed of carbon from the film forming raw material or by reacting with the foreign matter to vaporize the foreign matter, thereby preventing the foreign matter from entering the metal film. Is supplied to the film forming raw material storage unit or mixed with the vaporized film forming raw material to be mixed into the raw material gas supply path, a mixing suppression gas supply unit,
It is characterized by having.

The gas supply mechanism of the present invention includes a film forming raw material storage section for storing a film forming raw material that is a solid or liquid metal chloride,
A raw material gas supply path for supplying the vaporized film forming raw material to the processing container in order to form a metal film composed of a metal constituting the metal chloride on a substrate stored in the processing container;
A carrier gas supply unit configured to supply a carrier gas to the film forming material storage unit and introduce the film forming material vaporized together with the carrier gas into the source gas supply path;
A foreign matter mixing suppression gas for suppressing the precipitation of foreign matter composed of carbon from the film forming raw material or by reacting with the foreign matter to vaporize the foreign matter, thereby preventing the foreign matter from entering the metal film. Is supplied to the film forming raw material storage unit or mixed with the vaporized film forming raw material to be mixed into the raw material gas supply path, a mixing suppression gas supply unit,
It is characterized by having.

  According to the present invention, in the metal film formed on the substrate in the processing container by suppressing the precipitation of the foreign material composed of carbon from the film forming raw material or reacting with the foreign material to vaporize the foreign material. A mixing suppression gas for suppressing the mixing of foreign substances is supplied to a film forming raw material reservoir, or supplied to a raw material gas supply path connected to a processing container so as to be mixed with the vaporized film forming raw material. With such a configuration, it is possible to suppress the above foreign matter from being mixed into the metal film formed on the substrate.

It is a block diagram of the film-forming apparatus which concerns on this invention. It is explanatory drawing which shows the gas flow at the time of the film-forming process in the said film-forming apparatus. It is explanatory drawing which shows the gas flow at the time of the film-forming process in the said film-forming apparatus. It is explanatory drawing which shows the gas flow at the time of the film-forming process in the said film-forming apparatus. It is explanatory drawing which shows reaction in the film-forming raw material storage part which comprises the said film-forming apparatus. It is explanatory drawing of the cleaning performed by the gas supply mechanism which comprises the said film-forming apparatus. It is a block diagram which shows the film-forming apparatus of the other structure based on this invention.

A film forming apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. The film forming apparatus 1 is configured to form a W film on a wafer B by ALD (Atomic Layer Deposition). In this embodiment, WCl ₅ is used as a raw material for forming the W film. The film forming apparatus 1 includes a processing container 11 in which a wafer B is accommodated, and a raw material gas supply mechanism 2 for vaporizing solid WCl ₅ into a raw material gas and supplying the raw material gas together with a carrier gas. Yes. As will be described later, the raw material gas supply mechanism 2 is configured to supply the raw material gas to the processing container 11 so as not to include solid particles made of carbon. Note that vaporization in this specification includes sublimation.

In the processing container 11, a horizontal mounting table 12 on which the wafer B is mounted is provided. A heater 13 is embedded in the mounting table 12, and the mounted wafer B can be heated to a desired temperature. In the figure, reference numeral 14 denotes an exhaust pipe whose one end is opened in the processing container 11, and the other end of the exhaust pipe 14 is connected to a vacuum exhaust part 15 constituted by a vacuum pump or the like. The evacuation unit 15 evacuates the inside of the processing vessel 11 through the exhaust pipe 14 so that a vacuum atmosphere with a desired pressure is obtained. In the figure, 16 is a gas shower head provided in the ceiling portion of the processing container 11 so as to face the mounting table 12. A number of discharge holes 17 are provided on the lower surface of the gas shower head 16, and various gases supplied to the gas shower head 16 through the discharge holes 17 are discharged in a shower shape toward the mounting table 12. The

Next, the source gas supply mechanism 2 will be described. The source gas supply mechanism 2 includes a source gas supply pipe 21, a carrier gas supply pipe 22, an additive gas supply pipe 23, a bypass pipe 24, valves provided in these pipes, and an N ₂ (nitrogen) gas supply source. 25, an H ₂ (hydrogen) gas supply source 26, mass flow controllers (MFC) 27 and 28, and a raw material container 31. One end of a source gas supply pipe 21 that forms a source gas supply path for supplying source gas to the gas shower head 16 is connected to the processing container 11, and the other end of the source gas supply pipe 21 is connected to the valve V <b> 1. , V2 and V3 are connected to a raw material container 31 in which solid WCl ₅ is stored. The source gas supply pipe 21 is provided with, for example, a heater (not shown) on the outside thereof, and the inside of the pipe is heated during the film forming process, and the source gas flowing through the pipe is suppressed from being solidified by being cooled. The

In the raw material container 31, WCl ₅ is stored on the lower side thereof, and the other end of the raw material gas supply pipe 21 is open to an upper gas phase portion in the raw material container 31. The raw material container 31 includes a heater 32. The heater 32 surrounds the outside of the raw material container 31 and heats the raw material container 31 so that WCl ₅ is vaporized when the carrier gas is supplied into the raw material container 31.

A carrier gas supply pipe 22 is connected to a raw material container 31 that forms a film forming raw material reservoir, and one end of the carrier gas supply pipe 22 opens into a gas phase portion in the raw material container 31. The other end of the carrier gas supply pipe 22 is connected to the N ₂ gas supply source 25 through the valve V4, the valve V5, and the MFC 27 in this order. As the carrier gas N ₂ gas supply source 25 is a carrier gas supply unit, N ₂ gas is an inert gas, through the carrier gas supply pipe 22, it is supplied to the raw material container 31. The MFC 27 adjusts the flow rate of the N ₂ gas supplied to the downstream side of the MFC 27. As the carrier gas, any gas inert to WCl ₅ may be used. Therefore, for example, Ar (argon) gas may be used instead of N 2 gas.

The valve V4 and the valve V5 in the carrier gas supply pipe 22 and the valve V2 and the valve V3 in the source gas supply pipe 21 are connected by a bypass pipe 24 having a valve V6 interposed therebetween. The bypass pipe 24 closes the valves V3 and V4 and opens the valves V2, V5 and V6 before connection to the carrier gas supply pipe 22 and the raw material gas supply pipe 21 of the raw material container 31, and opens the carrier gas supply pipe 22 and the bypass pipe. 24 and the raw material gas supply pipe 21 are used for flowing N ₂ gas from the N ₂ gas supply source 25 and removing the gas remaining in each of these pipes.

One end of the additive gas supply pipe 23 is connected between the valve V5 and the MFC 27 in the carrier gas supply pipe 22, and the other end of the additive gas supply pipe 23 is connected to the H ₂ gas supply source via the MFC 28. 26. Therefore, H ₂ gas can be supplied to the raw material container 31. This H ₂ gas is a foreign matter mixing suppression gas that suppresses the mixing of the aforementioned particles into the W film formed on the wafer B. Therefore, the H ₂ gas supply source 26 is a foreign matter mixing suppression gas supply unit. is there. A relatively small amount of the H ₂ gas is an additive gas that is added to the carrier gas and supplied to the raw material container 31. The action of the H 2 gas will be described in detail later. The MFC 28 adjusts the flow rate of the H ₂ gas supplied to the downstream side of the MFC 28.

In addition, one end of the pipe 34 and one end of the pipe 35 are connected to the downstream side of the valve V1 in the source gas supply pipe 21. The other end of the pipe 34 is connected to an H ₂ gas supply source 36 via a valve V7, and the other end of the pipe 35 is connected to an N ₂ gas supply source 37 via a valve V8. Thus, _{H 2} gas supply source 36, _{H 2} gas from the _{N 2} gas supply source 37, _{N 2} gas is supplied to the respective gas shower head 16 is discharged into the processing vessel 11.

The H ₂ gas supplied from the H ₂ gas supply source 36 which is a reaction gas supply unit undergoes a reduction reaction with a source gas composed of WCl ₅ adsorbed on the wafer B, thereby forming a reaction gas (reducing gas) for forming a W film. ). Thereafter, in order to distinguish from the H2 gas supplied from the H2 gas supply source 26 to the raw material container 31, the H2 gas supplied from the H2 gas supply source 36 to the processing container 11 in this way is referred to as reducing H2 gas. May be described. The N 2 gas supplied from the N 2 gas supply source 37 is a replacement gas for purging the gas in the processing container 11 and replacing the atmosphere in the processing container 11 with the N 2 gas atmosphere. In order to distinguish from the N2 gas supplied from the N2 gas supply source 25 to the raw material container 31, the N2 gas supplied from the N2 gas supply source 37 to the processing container 11 may be described as a purge N2 gas. Yes. Although the N2 gas supply source and the H2 gas supply source are shown as being separately provided in the raw material container 31 and the processing container 11 as described above, they are common to the raw material container 31 and the processing container 11. May be used.

  Further, the film forming apparatus 1 includes a control unit 10. The control unit 10 is configured by a computer and includes a program, a memory, and a CPU. The program incorporates a group of steps so that a series of operations described later in the film forming apparatus 1 can be performed, and the control unit 10 outputs a control signal to each part of the film forming apparatus 1 according to the program. The operation of each part is controlled. Specifically, the valves V1 to V8 are opened and closed, the gas is supplied from the gas supply sources 25, 26, 36, and 37 to the pipes, the flow rate of the gas flowing downstream by the MFCs 27 and 28 is adjusted, and the vacuum exhaust unit 15 The operations such as the adjustment of the pressure in the processing container 11 by the above, the adjustment of the temperature of the wafer B by the heater 13 of the mounting table 12 and the adjustment of the temperature in the raw material container 31 by the heater 32 are controlled by the control signal. The above program is stored in a storage medium such as a compact disk, a hard disk, or a DVD and installed in the control unit 10.

Next, the reason why the film forming apparatus 1 is configured to be able to supply H ₂ gas from the H ₂ gas supply source 26 to the raw material container 31 will be described. As described in the section of the problem to be solved by the invention, a carbon compound may be mixed in the process of manufacturing WCl ₅ that is a film forming raw material. For example, it is assumed that the carbon compound is CH ₄ (methane). For example, the film forming apparatus 1 is provided in a normal temperature atmosphere, but the Gibbs free energy of the following formula 1 is a negative value at a temperature equal to or higher than the normal temperature. That is, the reaction of Formula 1 proceeds spontaneously, and WC (tungsten carbide) and Cl ₂ (chlorine) are generated from WCl ₅ and CH ₄ . Moreover, the Gibbs free energy of following formula 2 becomes a negative value in room temperature-250 degreeC. That is, the reaction of Formula 2 also proceeds spontaneously, and C (carbon) is generated from WC and Cl ₂ .
WCl ₅ + CH ₄ → WC + HCl + 1 / 2Cl ₂ Formula 1
2WC + 5Cl ₂ → 2WCl ₅ + 2C Formula 2

More specifically, WCl ₅ stored in the raw material container 31 as a film forming raw material is a relatively large solid particle. The surface of the grain is denatured as shown in the above formula 1 to become WC, and carbon is precipitated as fine solid grains as shown in the above formula 2 from the so altered surface. Since the deposited carbon is very small, when the carrier gas (N ₂ gas) is supplied to the raw material container 31 during the film forming process, it is supplied to the processing container 11 along the flow of the carrier gas. The Then, it will be mixed into the W film formed on the wafer B.

Therefore, in the film forming apparatus 1, in order to vaporize WCl ₅ during the film forming process, for example, when the inside of the raw material container 31 is heated to 125 ° C. to 165 ° C., it is added to the carrier gas in the raw material container 31. H ₂ gas is supplied. The temperature in the raw material container 31, WCl ₅ is not decomposed, and the carrier gas is at a temperature capable of performing the vaporization of the WCl ₅ by being supplied. In the raw material container 31, Cl ₂ is generated from WCl _{5 as} shown in Equation 1 above. There is also Cl ₂ decomposed from WCl _{5 by} a route other than that of Equation 1. The H ₂ gas supplied into the raw material container 31 reacts with the Cl ₂ to generate HCl (hydrogen chloride). In order to generate carbon particles from the WC and HCl, the reaction represented by the following formula 3 needs to occur. However, the Gibbs free energy of Formula 3 is a positive value at a temperature equal to or higher than room temperature. Therefore, the reaction of Formula 3 does not occur spontaneously in the raw material container 31 heated as described above, and no carbon particles are generated by HCl. As a result of Cl ₂ by reacting with H ₂ gas supplied into the raw material container 31 as described above is consumed, the reaction proceeds according to formula 2 above is suppressed. As a result, the generation of carbon particles in the raw material container 31 is suppressed.
WC + 5HCl → WCl ₅ + C + 2.5H ₂ Formula 3

In addition, as a formula 4, a reaction in which CCl ₄ (carbon tetrachloride) is generated from C and HCl is shown below. Since the Gibbs free energy of Formula 4 is negative at room temperature to 300 ° C., the reaction of Formula 4 proceeds spontaneously. And in the temperature in the raw material container 31 heated as mentioned above, C is solid, but CCl ₄ is gas. That is, C is vaporized by becoming CCl ₄ by the reaction of Formula 4. By vaporizing C in this way, it is possible to suppress C from adhering to the wafer B in the form of solid particles.
C + 4HCl → CCl ₄ + H ₂ Formula 4

Thus, the H ₂ gas suppresses the precipitation of C, and vaporizes C by changing to HCl. By the way, although explained as what WC produces | generates from methane, said WC can be produced | generated also from the compound (hydrocarbon compound) which consists of C and H, such as organic compounds containing carbon other than methane, for example, toluene, xylene. . That is, the present invention is not limited to using a metal chloride containing methane as an impurity as a film forming material.

Next, the operation of the film forming apparatus 1 will be described with reference to the schematic views of the film forming apparatus 1 shown in FIGS. 2 to 4, the part where the gas is circulating in each pipe is shown thicker than the part where the gas is not flowing. In addition, among the valves V1 to V8, those that are closed are shaded to distinguish the opened valves.

First, in a state where the valves V1 to V8 are closed, the inside of the raw material container 31 is heated by the heater 32 so as to have the temperature described above. On the other hand, for example, a wafer B having a TiN (titanium nitride) film formed on the surface thereof is loaded into the processing container 11 and mounted on the mounting table 12 by a substrate transport mechanism (not shown). Then, the wafer B is heated to, for example, 300 ° C. to 550 ° C. so that film formation can be performed, and the inside of the processing container 11 is set to a vacuum atmosphere at a predetermined pressure.

Thereafter, the valve V1~V5 is opened, _{N 2} gas from the _{N 2} gas supply source 25, _{H 2} gas supply source 26 as a carrier gas, _{H 2} gas is added gas is supplied to the respective raw material container 31 The FIG. 5 shows the reaction that occurs in the raw material container 31 when the N 2 gas and the H 2 gas are supplied in this way. Referring to FIG. 5 as well, the solid WCl ₅ heated in the raw material container 31 is vaporized by being exposed to N 2 gas and H 2 gas, and becomes a raw material gas. Further, H2 gas may react with Cl ₂ that is generated in the raw material container 31 as previously described, HCl is produced. Cl2 is consumed by the reaction, and HCl does not react with WC as described in Equation 3 above, so that precipitation of C from WC is suppressed. Further, the solid particles, which are carbon precipitated in the raw material container 31, are vaporized into CCl ₄ by the HCl as described in the above equation 4. Then, N ₂ gas and H ₂ gas flow to the raw material gas supply pipe 21, and vaporized WCl ₅ (raw material gas), CCl ₄ gas, and HCl gas also flow to the raw material gas supply pipe 21 along the flow. Further, C which has not reacted with HCl in the raw material container 31 also flows to the raw material gas supply pipe 21. This C reacts with HCl while flowing through the raw material gas supply pipe 21 to vaporize as CCl ₄ .

Each gas flowing this way the raw material gas supply pipe 21 is discharged from the gas shower head 16 to the wafer B, WCl ₅ gas is adsorbed on the TiN film formed on the surface of the wafer B (FIG. 2, Step S1). As described above, the CCl ₄ gas is supplied to the wafer B. That is, carbon is supplied to the wafer B. However, since carbon is supplied as a gaseous compound in this way, most of the carbon is exhausted without remaining on the surface of the wafer B. In other words, the amount of C mixed into the W film is suppressed as compared with the case where H ₂ gas is not supplied to the raw material container 31 and solid C is supplied to the wafer B.

Thereafter, the valve V1 is closed and the supply of gas to the processing container 11 is stopped. When the valve V1 is closed, the valve V8 is opened, and the purge N ₂ gas is supplied from the gas shower head 16 into the processing container 11. The purge N ₂ gas is supplied into the processing container 11 in step S1, and each gas remaining in the processing container 11 is purged and removed from the processing container 11 (FIG. 3, step S2). ).

Thereafter, the valve V8 is closed to stop the supply of the purge N ₂ gas into the processing container 11 and the valve V7 is opened to supply the reducing H ₂ gas into the processing container 11 from the gas shower head 16. Is done. With this reducing H ₂ gas, the WCl ₅ gas adsorbed on the wafer B is reduced to form a thin layer of W (FIG. 4, step S3). Thereafter, the valve V7 is closed, the supply of the reducing H ₂ gas into the processing container 11 is stopped, and the valve V8 is opened, so that the purge N ₂ gas is supplied from the gas shower head 16 into the processing container 11. . With this purge N ₂ gas, the reducing H 2 gas remaining in the processing container 11 is purged and removed from the processing container 11 (FIG. 3, step S 4).

Subsequently, the valve V8 is closed to stop the supply of the purge N2 gas into the processing container 11, and the valve V1 is opened to supply the gas to the processing container 11 again. That is, the above step S1 is performed again. Since the valves V2 to V5 are closed during the execution of steps S2 to S4, the inside of the raw material container 31 and the inside of the raw material gas supply pipe 21 are in a pressurized state. The raw material gas is supplied to the processing container 11 at a large flow rate. After step S1 is performed, steps S2 to S4 are performed, and thereafter steps S1 to S4 are further performed. That is, assuming that the above steps S1 to S4 are one cycle, this cycle is repeated. Thereby, a thin layer of W is deposited, and a W film is formed so as to be laminated on the TiN film formed on the surface of the wafer B. Then, when a predetermined number of cycles are executed and the W film has a predetermined thickness, the supply of each gas into the processing container 11 is stopped, and the wafer B is unloaded from the processing container 11.

As described above, according to the film forming apparatus 1, the H ₂ gas is supplied into the raw material container 31 in which the solid WCl ₅ that is the film forming raw material is stored. This H ₂ gas suppresses the precipitation of C in the raw material container 31. Further, the deposited C is vaporized as CCl ₄ by the HCl gas generated from the H ₂ gas, so that the adhesion of C to the wafer B in a solid state is suppressed. Therefore, it is possible to prevent C particles from entering the W film formed on the wafer B as foreign matter.

In step S1, for example, WCl ₅ (molecular weight 361.12) is supplied to the wafer B at 140 mg / min, that is, 3.88 × 10 ⁻⁴ mol / min, to form a film. When H ₂ gas is not supplied to the raw material container 31, it is estimated that 1% of carbon is contained with respect to the amount of WCl ₅ flowing through the raw material gas supply pipe 21. That is, carbon is supplied from the raw material container 31 to the processing container 11 at 3.88 × 10 ⁻⁵ mol / min. By the way, from the above formula 4, in order to vaporize 1 mol of carbon, 4 mol of HCl may be present. If 2 mol of H2 gas is present, 4 mol of HCl can be generated. Therefore, if 2 mol of H2 gas is present relative to 1 mol of carbon, 1 mol of carbon can be vaporized. However, in reality, only a part of the supplied H ₂ gas becomes HCl and reacts with carbon, and the other part becomes unreacted. For example, the amount of H 2 is 4 times or more of 1 mol of carbon. Supply gas. Therefore, if the supply amount of carbon from the raw material container 31 is 3.88 × 10 ⁻⁵ mol / min as described above, 1 sccm of H ₂ gas (= mL / min) is 4.4E ⁻⁵ mol / min. Therefore, for example, H ₂ gas is supplied to the raw material container 31 at 1 sccm. As will be described later, if the flow rate of the H ₂ gas is too large, problems occur. Therefore, it is preferable to supply the H 2 gas at around 1 sccm, more specifically, for example, 0.5 sccm to 1.5 sccm.

By the way, H ₂ gas reduces WCl ₅ to W. Therefore, if the flow rate of the H ₂ gas supplied to the raw material container 31 is too large, W is generated in such a manner and the raw material gas cannot be generated. Therefore, in step S1, the H ₂ gas is supplied to the raw material container 31 at a relatively small flow rate. Specifically, in order to prevent the reduction of WCl ₅ , the flow rate of the H ₂ gas supplied from the H ₂ gas supply source 26 to the raw material container 31 in the above step S 1 is changed from the N ₂ gas supply source 25 to the raw material container 31. The flow rate is made smaller than the flow rate of the supplied N ₂ gas. Further, if the flow rate of the H ₂ gas supplied to the raw material container 31 is too small, the effect of the H ₂ gas described above cannot be obtained sufficiently. Therefore, the flow rate supplied to the raw material container 31 of H2 gas: The flow rate supplied to the raw material container 31 of N2 gas is preferably set to, for example, 1: 100 to 1: 200.

Further, when performing film formation in the film formation apparatus 1 described above, the H ₂ gas is not limited to being supplied to the raw material container 31 during the execution of step S1, for example, when steps S2 to S4 are performed. Alternatively, the raw material container 31 may be supplied. That is, the period for supplying the N2 gas to the raw material container 31 and the period for supplying the H2 gas to the raw material container 31 do not have to overlap each other. However, since the flow rate of the H2 gas is relatively small as described above, when the H2 gas is supplied alone to the raw material container 31, the concentration of the H2 gas may be biased in the raw material container 31. In order to sufficiently distribute a relatively small amount of H 2 gas to the raw material container 31 with high uniformity and sufficiently suppress the precipitation of C from WC and generate CCl 4 throughout the raw material container 31, As in the example of the film treatment, it is preferable that the period in which the H 2 gas is supplied overlaps the period in which the N 2 gas is supplied.

2 to 4, WCl ₅ is deposited on the source gas supply pipe 21 to form a deposit, and an organic compound such as methane, which is an impurity contained in the film forming raw material from the raw material container 31. Flows into the source gas supply pipe 21, the surface of the deposit becomes WC, and carbon may be deposited on the surface of the deposit. That is, after the film forming process, the reactions of the above formulas 1 and 2 occur in the source gas supply pipe 21 and there is a possibility that carbon particles are generated. Therefore, the source gas supply pipe 21 may be cleaned after the film forming process described with reference to FIGS. Hereinafter, this cleaning will be described. The valves V1 to V8 are closed, the wafer B is not loaded into the processing container 11, and the processing container 11 is evacuated. Then, the valves V1, V2, V5, and V6 are opened, and the raw material is shown in FIG. H ₂ gas is supplied to the gas supply pipe 21. In FIG. 6 and FIG. 7 to be described later, similarly to FIGS. 2 to 4, the portion where the gas flows in each pipe is shown thick, and the closed valve V is shown by hatching.

The H ₂ gas supplied to the source gas supply pipe 21 as described above reacts with Cl ₂ generated from WCl ₅ in the source gas supply pipe 21 to generate HCl, and this HCl causes the surface of the deposit to be formed. The precipitated carbon becomes CCl ₄ . Thus, during the supply of H ₂ gas, the inside of the source gas supply pipe 21 is heated by, for example, a heater provided in the source gas supply pipe 21 so that the generated CCl ₄ has a gas temperature. . That is, the reaction described in the above equation 4 is caused to occur in the source gas supply pipe 21. The CCl ₄ gas thus generated in the source gas supply pipe 21 is supplied to the processing container 11 together with the H ₂ gas, exhausted and removed. Thus the H ₂ gas supplied from the H2 gas supply source 26 to the source gas supply pipe 21 is used as a cleaning gas for cleaning the raw material gas supply pipe 21. As described above, the source gas supply mechanism 2 provided in the film forming apparatus 1 can clean the pipes in addition to performing the film forming.

Although an example of using WCl ₅ as a film forming raw material has been shown, a raw material gas is generated using WCl ₄ (tungsten tetrachloride) or WCl ₆ instead of WCl ₅ as a film forming raw material to form a W film. Also good. When WCl ₄ and WCl ₆ are used in such a manner, WC is considered to be generated by the same reaction as in the above-described formula 1. Therefore, by supplying H ₂ gas, suppression of C precipitation and generation of CCl ₄ are possible. The particles mixed in the W film can be reduced. However, when the TiN film is formed on the surface of the wafer B as described above, the TiN film may be etched by the source gas used. Since the above WCl ₅ can suppress the etching of the TiN film, it is preferable to use WCl ₅ as a film forming raw material when the W film is laminated on the TiN film as described above.

Since the HCl gas generated from the H2 gas reacts with the particles as described above, it is conceivable to supply the HCl gas to the raw material container 31, but the raw material gas supply pipe 21 and the processing container 11 are made of, for example, metal, and HCl gas is more corrosive to metals than H2 gas. In the film forming apparatus 1, HCl gas is not directly supplied to the source gas supply pipe 21 and the processing container 11, and HCl is generated only as much as the H 2 gas reacts with Cl 2 as described above. That is, the film forming apparatus 1 is preferable because the concentration of HCl in the source gas supply pipe 21 and the processing container 11 can be kept low, and the lifespan of the source gas supply pipe 21 and the processing container 11 can be kept long. . In the film forming apparatus 1, H 2 gas, which is the same type of gas as the reducing H 2 gas supplied to reduce WCl ₅ adsorbed on the wafer B, is supplied to the raw material container 31. Therefore, even if the H 2 gas supplied to the raw material container 31 flows into the processing container 11, there is no influence on the properties of the W film, or it is preferable that there is almost no effect.

By the way, the position where the H 2 gas is supplied is not limited to the raw material container 31. The film forming apparatus 42 shown in FIG. 7 will be described as an example. The difference between the film forming apparatus 42 and the film forming apparatus 1 is that a raw material gas supply pipe 21 is provided with a tank 43. Can be mentioned. The downstream end of the additive gas supply pipe 23 is connected to the tank 43 instead of being connected to the carrier gas supply pipe 22. That is, a part of the source gas supply pipe 21 is configured as a tank 43, and H ₂ gas is supplied to the tank 43.

In the film forming apparatus 42, among the valves V1 to V6, as shown in FIG. 7, the valves V1 and V6 are closed and the valves V2 to V5 are opened, so that the N ₂ gas is supplied to the N ₂ gas supply source 25. Is supplied to the raw material container 31, and the raw material gas composed of WCl ₅ flows into the raw material gas supply pipe 21 and is stored in the tank 43. At this time, Cl ₂ gas and carbon particles generated in the raw material container 31 are also supplied to the tank 43 and stored together with the raw material gas. Further, H ₂ gas is supplied to the tank 43, is stored from the H ₂ gas supply source 26 in parallel with the supply of the source gas into the tank 43. Accordingly, the raw material gas and the H 2 gas are mixed in the tank 43. In the tank 43, HCl is generated from H ₂ and Cl _2, and C is vaporized as CCl ₄ . That is, the reaction of the above formula 4 occurs in the tank 43.

Each gas stored in the tank 43 is supplied into the processing container 11 by opening the valve V1, and step S1, which is the above-described raw material gas adsorption process, is performed. Thereafter, the valve V1 is closed, and the raw material gas and the H2 gas are stored in the tank 43 again. Thus, while each gas is stored in the tank 43, the valves V7 and V8 are opened and closed so that the above-described steps S2 to S4 are performed. FIG. 7 shows a state when the reducing H2 gas is supplied to the processing container 11 in step S3.

In this film forming apparatus 42, the same effect as the film forming apparatus 1 can be obtained. Meanwhile the raw material gas and H2 gas is configured to be stored a part of the raw material gas supply pipe 21 as a tank 43 in the film deposition device 42, HCl is produced from the supplied H2 gas, CCl ₄ is a particle carbon This is to sufficiently secure the reaction time required for vaporization. In the film forming apparatus 1, the H ₂ gas is supplied to the raw material container 31 that is relatively far away from the processing container 11, so that carbon becomes CCl _{4 and} vaporizes before the carbon particles reach the processing container 11. Sufficient time can be secured. In other words, the film forming apparatus 1 is more preferable because the carbon can be sufficiently vaporized as CCl 4 without providing the tank 43, and the apparatus configuration can be simplified. Further, as described above, the carbon particles are generated from the film forming raw material that has become WC. However, the film forming apparatus 1 supplies H2 gas to the raw material container 31 in which the film forming raw material is stored, as described above. In addition, since the precipitation of C from WC is suppressed, carbon particles can be more reliably prevented from being mixed into the W film.

In the above film forming process, an example is shown in which film formation is performed by ALD in which a source gas composed of WCl ₅ and a reducing H ₂ gas are alternately and repeatedly supplied to the wafer B. In this way, film formation is performed by ALD. Not limited to that. For example, a source gas composed of WCl ₅ is supplied to wafer B for a relatively long time to deposit WCl ₅ to form a film, and then H 2 gas is supplied to wafer B for a relatively long time to deposit WCl 5. _A W film may be formed by reducing ₅ . That is, film formation by CVD (Chemical Vapor Deposition) may be performed. Further, as a reducing gas used for forming a W film by reducing WCl ₅ , for example, a gas having a reducing property with respect to WCl ₅ other than H ₂ such as diborane (B ₂ H ₆ ) may be used. .

Further, the gas supplied to the raw material container 31 is not limited to the H2 gas, and a gas in which precipitation of C from WC is suppressed by reacting with Cl2 in the raw material container 31 and consuming the Cl2 can be used.

Although it has been described that carbon as a simple substance is a particle, if it is a compound composed of carbon that reacts with HCl to generate CCl ₄ and is vaporized, the carbon as a simple substance is limited to being a particle. Absent.

Further, the metal chloride as a film forming raw material is not limited to tungsten chloride, and other metal chlorides may be used as the film forming raw material. Even in that case, by supplying H2 gas to the film forming raw material, HCl is generated from the H2 gas and the metal chloride, and particles that are compounds composed of carbon contained in the film forming raw material are vaporized by the HCl. The particles can be prevented from being mixed into the film formed on the wafer B by the metal contained in the film forming raw material. In the example described above, H ₂ gas is supplied to the metal chloride and reduced to form a metal film on the wafer W. However, instead of H ₂ gas, O ₂ (oxygen), O ₃ ( The present invention also applies when forming a metal oxide film on the wafer W by supplying an oxidizing gas such as ozone) or when forming a metal nitride film on the wafer W by supplying a nitriding gas such as NH ₃ (ammonia) gas. Can be applied. It should be noted that the film forming raw material only needs to be vaporized and particles removed when being supplied to the wafer B. The state stored in the raw material container 31 is not limited to a solid state, but in a liquid state. It may be stored in the raw material container 31. Note that the present invention is not limited to the above-described embodiments, and the embodiments can be appropriately changed or combined with each other.

B Wafer 1 Film forming apparatus 10 Control unit 11 Processing vessel 2 Source gas supply mechanism 21 Source gas supply tube 25 N2 gas supply source 26 H2 gas supply source 31 Source vessel

Claims (9)

A processing container for containing a substrate;
A film forming raw material reservoir for storing a film forming raw material that is a solid or liquid metal chloride;
A raw material gas supply path for supplying the vaporized film forming raw material to the processing vessel in order to form a metal film composed of a metal constituting the metal chloride on the substrate;
A carrier gas supply unit configured to supply a carrier gas to the film forming material storage unit and introduce the film forming material vaporized together with the carrier gas into the source gas supply path;
A foreign matter mixing suppression gas for suppressing the precipitation of foreign matter composed of carbon from the film forming raw material or by reacting with the foreign matter to vaporize the foreign matter, thereby preventing the foreign matter from entering the metal film. Is supplied to the film forming raw material storage unit or mixed with the vaporized film forming raw material to be mixed into the raw material gas supply path, a mixing suppression gas supply unit,
A film forming apparatus comprising the film forming device.   The film formation apparatus according to claim 1, wherein the mixing suppression gas supply unit supplies the mixing suppression gas to the film forming raw material storage unit.   The film forming apparatus according to claim 2, wherein a period during which the mixing suppression gas is supplied to the film forming raw material storage unit and a period during which the carrier gas is supplied to the film forming raw material storage unit overlap each other. . The film forming apparatus according to claim 1, wherein the metal chloride is tungsten chloride. In order to form the metal film, there is provided a reaction gas supply unit that supplies a reaction gas that reacts with a film forming raw material supplied to the substrate to the processing container,
The film forming apparatus according to claim 1, wherein the reaction gas and the mixing suppression gas are gases having a reducing property with respect to a film forming raw material. The film forming apparatus according to claim 5, wherein the reaction gas and the mixing suppression gas are the same gas. The film forming apparatus according to claim 1, wherein the mixing suppression gas is hydrogen gas. A film forming raw material reservoir for storing a film forming raw material that is a solid or liquid metal chloride;
A raw material gas supply path for supplying the vaporized film forming raw material to the processing container in order to form a metal film composed of a metal constituting the metal chloride on a substrate stored in the processing container;
A carrier gas supply unit configured to supply a carrier gas to the film forming material storage unit and introduce the film forming material vaporized together with the carrier gas into the source gas supply path;
A foreign matter mixing suppression gas for suppressing the precipitation of foreign matter composed of carbon from the film forming raw material or by reacting with the foreign matter to vaporize the foreign matter, thereby preventing the foreign matter from entering the metal film. Is supplied to the film forming raw material storage unit or mixed with the vaporized film forming raw material to be mixed into the raw material gas supply path, a mixing suppression gas supply unit,
A gas supply mechanism comprising: After the vaporized film forming raw material is supplied to the raw material gas supply path,
The said mixing suppression gas supply part supplies the mixing suppression gas of the said foreign material to the said raw material gas supply path as a cleaning gas for removing the said foreign material in the said raw material gas supply path. Gas supply mechanism.

Images