JP2014062281A - Method of forming metal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a metal film in which the metal film including less impurities can be formed with high throughput through CVD.SOLUTION: A metal film is formed through: a first process of arranging a substrate to be treated in a treating vessel and forming an initial metal film through CVD by supplying onto the substrate to be treated a film forming material comprising a metal-containing compound which has a ligand having a nitrogen-carbon bond in a molecular structure and has a structure where nitrogen in the ligand is coordinated with metal and a reducing gas comprising at least one kind selected out of ammonia, hydrazine, and derivatives thereof; a second process of subjecting the substrate to be treated to hydrogen treatment by supplying a hydrogen gas into the treating container; and a third process of forming a main metal film through CVD by supplying onto the initial metal film formed on the substrate to be treated a film forming material comprising the same metal-containing compound with the first process and a reducing gas composed of a hydrogen gas.

Description

  The present invention relates to a metal film forming method for forming a metal film by chemical vapor deposition (CVD).

  In recent years, semiconductor devices have been demanded to further increase the operation speed and reduce power consumption. For example, in order to reduce the resistance of source and drain contact portions and gate electrodes of MOS type semiconductors, Silicide is formed by the salicide process. As such a silicide, nickel silicide (NiSi), which consumes less silicon and can reduce resistance, has attracted attention.

  For forming a NiSi film, a method of forming a nickel (Ni) film on a Si substrate or a polysilicon film by a physical vapor deposition (PVD) method such as sputtering and then annealing and reacting in an inert gas is often used. (For example, Patent Document 1).

  Attempts have also been made to use the Ni film itself as a capacitor electrode of a DRAM.

However, with the miniaturization of semiconductor devices, PVD has become unable to obtain sufficient step coverage. Therefore, a method of forming a nickel film by a chemical vapor deposition (CVD) method with good step coverage has been studied. In Patent Document 2, nickel amidinate is used as a film forming material (precursor), and a reducing gas is used. It is disclosed that a nickel film is formed by CVD using ammonia (NH ₃ ).

However, when a Ni film is formed using these, since N is contained in the processing gas, N is taken into the film and nickel nitride (Ni _x is simultaneously formed when the Ni film is formed. N) is formed, and the resulting film becomes a Ni film containing N as an impurity, and the resistance of the film becomes high.

In order to improve such a point, in Patent Document 3, a nickel film containing N is formed using nickel amidinate and NH _3, and then the film is reformed in a hydrogen atmosphere. Of N is disclosed.

JP-A-9-153616 JP 2011-66060 A International Publication No. 2011/040385

  However, by adding a post process after film formation in this way, the processing time becomes longer, and the throughput is reduced. Moreover, in Patent Document 3, it is necessary to repeat the film formation and the modification process a plurality of times in order to increase the purity of the Ni film, and the processing time becomes longer. Such a problem is not limited to the case of forming a Ni film using an amidinate-based material, but has a ligand having a nitrogen-carbon bond in the molecular structure, and the nitrogen in the ligand is distributed to the metal. The same exists when a metal film is formed using a metal-containing compound having a coordinated structure.

  This invention is made | formed in view of this situation, Comprising: It aims at providing the film-forming method of the metal film which can form the metal film with few impurities by CVD by high throughput.

  In order to solve the above problems, the applicant of the present invention first has a ligand having a nitrogen-carbon bond in the molecular structure represented by nickel amidinate, and the nitrogen in the ligand is arranged on nickel. After forming an initial nickel film by CVD using a nickel-containing compound having a coordinated structure and at least one reducing gas selected from ammonia, hydrazine, and derivatives thereof, the nickel-containing compound and the reduction A nickel film forming method for forming a main nickel film by CVD using hydrogen gas as a gas has been proposed (Japanese Patent Application No. 2011-191917). Thereby, the main nickel film can be formed in a state where there are few impurities such as nickel nitride (Ni-N) and nickel carbide (Ni-C), and by the hydrogen gas used for the main nickel film, Nitrogen and the like in the initial nickel film can be removed.

  However, according to the examination results thereafter, the Ni—N and Ni—C impurities incorporated during the formation of the initial nickel film may not be sufficiently removed by hydrogen when forming the main nickel film. It has been found that such impurities deteriorate the specific resistance of the Ni film and cause poor formation of nickel silicide. The present invention solves such a new problem.

  That is, according to the present invention, a substrate to be processed is disposed in a processing container, and a ligand having a nitrogen-carbon bond in the molecular structure is provided on the substrate to be processed, and nitrogen in the ligand is arranged on the metal. A film forming raw material made of a metal-containing compound having a coordinated structure and a reducing gas consisting of at least one selected from ammonia, hydrazine, and derivatives thereof are supplied to form an initial metal film by CVD. One step, and then a second step in which hydrogen gas is supplied into the processing vessel to perform hydrogen processing on the substrate to be processed, and on the initial metal film formed on the substrate to be processed in the molecular structure. CVD having a ligand having a nitrogen-carbon bond, a film-forming raw material made of a metal-containing compound having a structure in which nitrogen in the ligand is coordinated to a metal, and a reducing gas made of hydrogen gas And a third step of forming a main metal film It provides a method of forming a metal film, characterized in that.

  In the present invention, a metal amidinate compound can be used as the metal-containing compound.

  Nickel amidinate can be used as the metal amidinate compound, and a nickel film can be formed as the metal film. In this case, the second step can be performed at 160 to 500 ° C., the pressure when the second step is performed can be 333 to 13330 Pa, and the second step is performed. The hydrogen gas flow rate can be 25 to 5000 mL / min (sccm).

  Moreover, the said 1st process and the said 3rd process can be performed at 200-350 degreeC, and the pressure at the time of implementing the said 1st process and the said 3rd process can be 133.3-2000 Pa. . In this case, the second step can be performed at the same temperature and the same pressure as the first step and the third step.

  Further, the present invention is a storage medium that operates on a computer and stores a program for controlling the film forming apparatus, and the program performs the metal 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, a metal-containing compound having a ligand having a nitrogen-carbon bond in a molecular structure and having a structure in which nitrogen in the ligand is coordinated to a metal, which can be formed on a substrate. After forming an initial metal film using ammonia and ammonia, hydrogen treatment is performed on the substrate to be processed by supplying hydrogen gas into the processing vessel, and then a similar metal-containing compound is formed thereon. Since the main metal film is formed using hydrogen gas, impurities in the initial metal film can be surely removed by hydrogen treatment, and in the subsequent main metal film formation, hydrogen is used as a reducing gas. It is formed as a film with very few impurities using a gas. For this reason, the obtained metal film has a high purity as a whole. In addition, the hydrogen treatment only removes impurities from the thin initial metal film, and it may be performed in a short time. In addition, in the main film formation using H ₂ gas as the reducing gas, compared to the case using NH ₃ gas. Since the film formation rate is high, the throughput can be significantly increased as compared with the conventional method of forming a film using NH ₃ as the reducing gas and annealing after the film formation.

It is a schematic diagram which shows an example of the film-forming apparatus for enforcing the film-forming method of the metal film which concerns on one Embodiment of this invention. It is a timing chart which shows the sequence of the film-forming method of the metal film which concerns on one Embodiment of this invention. It is a figure for demonstrating the mechanism in which an impurity is removed from an initial stage Ni film | membrane by hydrogen treatment. The film thickness direction by X-ray photoelectron spectroscopy (XPS) of a sample in which Ni (II) (tBu-AMD) ₂ is used as a film forming raw material and NH ₃ is used as a reducing gas and a Ni film is formed on a Si wafer. It is a figure which shows an elemental analysis result. A Ni film was formed on a Si wafer using Ni (II) (tBu-AMD) ₂ as a film forming material and NH ₃ as a reducing gas, and then hydrogen treatment was performed by supplying H ₂ gas. It is a figure which shows the elemental analysis result of the film thickness direction by X-ray photoelectron spectroscopy (XPS) of a sample.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In the present embodiment, a case where a nickel film is formed as a metal film will be described. FIG. 1 is a schematic view showing an example of a film forming apparatus for carrying out a metal film forming method according to an embodiment of the present invention.

  The film forming apparatus 100 has a substantially cylindrical chamber 1 that is hermetically configured, and a susceptor 2 for horizontally supporting a wafer W that is a substrate to be processed is an exhaust chamber described later. It is arrange | positioned in the state supported by the cylindrical support member 3 which reaches the center lower part from the bottom part. The susceptor 2 is made of a ceramic 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. Above the heater 5 inside the susceptor 2, an electrode 27 for applying high-frequency power is embedded. A high-frequency power source 29 is connected to the electrode 27 via a matching unit 28, and it is also possible to generate plasma by applying high-frequency power to the electrode 27 as necessary to perform plasma CVD. . 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.

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 film-forming gas supplied from a gas supply mechanism 30 to be described later into the chamber 1, and a first introduction path for introducing a film-forming material gas is provided above the shower head 10. 11 and a second introduction path 12 for introducing NH ₃ gas and H ₂ gas as reaction gas (reducing gas).

A nickel-containing compound used as a film forming source gas has a ligand having a nitrogen-carbon bond in the molecular structure, and has a structure in which nitrogen in the ligand is coordinated to nickel. And Ni (II) N, N′-di-tert-butylamidinate (Ni (II) (tBu-AMD) ₂ ) shown in FIG. Other nickel amidinates include Ni (II) N, N′-di-isopropylamidinate (Ni (II) (iPr-AMD) ₂ ), Ni (II) N, N′-di-ethyl. Examples thereof include amidinate (Ni (II) (Et-AMD) ₂ ), Ni (II) N, N′-di-methylamidinate (Ni (II) (Me-AMD) ₂ ) and the like.

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 discharges nickel amidinate as a film forming raw material gas, NH ₃ gas, and H ₂ gas independently 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 nickel-containing compound, which is a nickel-containing compound having a ligand having a nitrogen-carbon bond in the molecular structure as a film forming raw material and having a structure in which nitrogen in the ligand is coordinated to nickel. Film-forming raw material for storing dinate (Ni-AMD), for example, Ni (II) N, N′-di-tert-butylamidinate (Ni (II) (tBu-AMD) ₂ ) dissolved in a solvent A tank 31 is provided. A heater 31a is provided around the film forming material tank 31 so that the film forming material in the tank 31 can be heated to an appropriate temperature. In addition, when using a liquid thing at normal temperature as a nickel containing compound, it can store as it is, without melt | dissolving in a solvent.

  A bubbling pipe 32 for supplying Ar gas as a bubbling gas from above is inserted into the film forming material tank 31 so as to be immersed in the film forming material. An Ar gas supply source 33 is connected to the bubbling pipe 32, and a mass flow controller 34 as a flow rate controller and front and rear valves 35 are interposed. In addition, a raw material gas delivery pipe 36 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. 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 the film forming source gas. Then, by supplying Ar gas, which is a bubbling gas, to the film forming raw material, the film forming raw material is vaporized in the film forming raw material tank 31 by bubbling, and the generated film forming raw material gas is supplied to the raw material gas delivery pipe 36 and the first gas supply pipe 36. 1 is supplied into the shower head 10 through one introduction path 11.

  The bubbling pipe 32 and the raw material gas delivery pipe 36 are connected by a bypass pipe 48, and a valve 49 is interposed in the pipe 48. Valves 35a and 37a are provided on the downstream side of the connecting portion of the piping 48 in the bubbling piping 32 and the raw material gas delivery piping 36, respectively. Then, by closing the valves 35a and 37a and opening the valve 49, the argon gas from the Ar gas supply source 33 passes through the bubbling pipe 32, the bypass pipe 48, and the source gas delivery pipe 36 into the chamber 1 as a purge gas or the like. It is possible to supply.

A pipe 40 is connected to the second introduction path 12 of the shower head 10, and a valve 41 is provided in the pipe 40. The pipe 40 is branched into branch pipes 40a and 40b. An NH ₃ gas supply source 42 is connected to the branch pipe 40a, and an H ₂ gas supply source 43 is connected to the branch pipe 40b. The branch pipe 40a is provided with a mass flow controller 44 as a flow rate controller and a valve 45 before and after the mass flow controller 44, and the branch pipe 40b is provided with a mass flow controller 46 as a flow rate controller and a valve 47 before and after the mass flow controller 46. Has been. Incidentally, it is possible to use in place of NH _3, hydrazine or, NH ₃ derivatives, hydrazine derivatives.

  Further, when performing plasma CVD by applying high-frequency power to the electrode 27 as necessary, a branch pipe is further added to the pipe 40, and the mass flow controller and its front and rear are connected to this branch pipe. It is preferable to provide an Ar gas supply source for plasma ignition through a valve.

  The film forming apparatus 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 visualizes the operation status of each component of the film forming apparatus and the keyboard on which the operator inputs commands to manage each component of the film forming apparatus. It consists of a display that 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.

Next, a method for forming a metal film according to an embodiment of the present invention performed by the film forming apparatus 100 will be described.
First, the gate valve 25 is opened, and the wafer W is loaded into the chamber 1 through the loading / unloading port 24 by a transfer device (not shown) and placed on the susceptor 2. Next, the inside of the chamber 1 is evacuated by the exhaust device 23 to bring the inside of the chamber 1 to a predetermined pressure, and the susceptor 2 is heated to a predetermined temperature.

In this state, as shown in the timing chart of FIG. 2, nickel amidinate (which has a ligand having a nitrogen-carbon bond in the molecular structure, and nitrogen in the ligand is distributed to nickel as shown in the timing chart of FIG. A nickel-containing compound having a coordinated structure) and an NH ₃ gas as a reducing gas to form an initial Ni film (step 1), and the gas is stopped and _The hydrogen treatment step (step 2) for introducing hydrogen gas into the wafer W and introducing the hydrogen ablation raw material gas nickel amidate while continuing the introduction of the H ₂ gas A main film forming process (step 3) for forming a film and a purge process (step 4) for purging the chamber 1 are sequentially performed.

When a Ni film is formed on the surface of the wafer W (typically, the surface of a Si substrate or a polysilicon film) using nickel amidinate as a film forming raw material, even if H ₂ is used as a reducing gas, a nucleus is formed. Since it is not generated and Ni is not deposited, NH ₃ or the like is used as a reducing gas in the initial film forming step of Step 1. That is, in the initial film forming process of Step 1, nickel amidinate as a film forming raw material stored in the film forming raw material tank 31, for example, Ni (II) N, N′-di-tert-butyl amidinate. Ar gas as a bubbling gas is supplied to (Ni (II) (tBu-AMD) ₂ ), and nickel amidinate as a film forming raw material is vaporized by bubbling. Supplying into the chamber 1 through the path 11 and the shower head 10, NH ₃ gas as a reducing gas is supplied from the NH ₃ gas supply source 42 through the branch pipe 40 a, the pipe 40, the second introduction path 12, and the shower head 10. To supply into the chamber 1. Note that hydrazine, an NH ₃ derivative, or a hydrazine derivative can be used in place of the reducing gas NH ₃ . That is, as the reducing gas, at least one selected from NH ₃ , hydrazine, and derivatives thereof can be used. As the ammonia derivative, for example, monomethylammonium can be used, and as the hydrazine derivative, for example, monomethylhydrazine or dimethylhydrazine can be used. Of these, ammonia is preferred. These are reducing agents having unshared electron pairs, are highly reactive with nickel amidinate, and can easily obtain an initial Ni film on the surface of the wafer W even at a relatively low temperature. The film thickness of the initial Ni film formed in such an initial film forming process is preferably 3 to 15 nm.

すなわち、核となるＮｉにアミジネート配位子が結合しており、Ｎｉは実質的にＮｉ^２＋として存在している。 The nickel amidinate used as a film forming raw material is Ni (II) N, N′-di-tert-butylamidinate (Ni (II) (tBu-AMD) ₂ ) as an example (1 ).

That is, an amidinate ligand is bonded to Ni as a nucleus, and Ni substantially exists as Ni ²⁺ .

A reducing gas having an unshared electron pair, such as NH _3, is combined with the Ni nucleus existing as Ni ²⁺ of the nickel amidinate having the above structure, and the amidinate ligand is decomposed. As a result, the initial Ni film is formed with nickel nitride (Ni—N) as impurities due to nickel amidinate and NH ₃ -derived N. Ni-C is also generated as an impurity. Therefore, the generated initial Ni film has a large amount of impurities.

In the hydrogen treatment process of Step 2, the supply of nickel amidinate and NH ₃ gas is stopped, H ₂ gas is supplied into the chamber 1, and the wafer W after the initial Ni film formation is subjected to hydrogen treatment. At this time, the H ₂ gas is supplied from the H ₂ gas supply source 43 into the chamber 1 through the branch pipe 40 b, the pipe 40, the second introduction path 12, and the shower head 10. In this step 2, first, H ₂ gas is supplied and the inside of the chamber 1 is evacuated to purge the remaining nickel amidinate gas and NH ₃ gas, and then supply of H ₂ gas The pressure in the chamber 1 is controlled to a predetermined pressure while continuing. Thus, by supplying H ₂ gas into the chamber 1 and performing hydrogen treatment on the wafer W, as shown in FIGS. 3A and 3B, Ni film formed with nickel amidinate or NH ₃ is formed. Ni—N and Ni—C which are impurities in the film react with H ₂ gas to become NH ₃ and CH ₄ and are removed from the film. Thereby, an initial Ni film with few impurities is formed.

In the main film forming process of Step 3, the flow rate is adjusted while supplying the H ₂ gas, and the stopped nickel amidinate is supplied again in the same manner as in Step 1. As a result, the nickel amidinate is reduced by H ₂ gas, and Ni is further deposited on the initial Ni film to form a main Ni film. At this time, the impurities in the initial Ni film have been removed by the hydrogen treatment in step 2, and the nickel amidinate is reduced with H ₂ gas, so that the main Ni film is formed as a film with less impurities. Thus, the obtained Ni film has less impurities as a whole.

  The film thickness in the main film forming step of Step 3 is appropriately determined according to the total film thickness of the Ni film to be formed and the film thickness at the initial film formation. The film formation time is preferably determined in advance from the film thickness and the film formation rate.

In the purge process of Step 4, the supply of nickel amidinate and H ₂ gas is stopped and the inside of the chamber 1 is evacuated. At this time, the Ar gas from the Ar gas supply source 33 may be supplied into the chamber 1 as a purge gas via the bubbling pipe 32, the bypass pipe 48, and the source gas delivery pipe 36 as necessary.

  After the purge process is completed, the gate valve is opened, and the wafer W after film formation is unloaded through the loading / unloading port 24 by a transfer device (not shown).

Conventionally, as shown in Patent Document 3, nickel amidinate is used as a film forming material and NH ₃ is used as a reducing gas to form an entire Ni film, and then impurities in the Ni film are removed. For this reason, annealing in a hydrogen atmosphere is performed to remove N in the Ni film. However, if such annealing treatment is performed after the film formation, the throughput is reduced accordingly. If the film formation and the annealing process are repeated a plurality of times in order to obtain a higher-purity Ni film, the throughput is further reduced. Therefore, in the embodiment of the above Japanese Patent Application No. 2011-191917, after the initial film formation is performed in the same manner as the present embodiment, the main film is formed by changing the reducing gas to H ₂ gas.

Thus, the main film formation after the initial film formation is based on the following knowledge.
(1) After initial film formation was performed with nickel amidinate as a film forming raw material and NH ₃ as a reducing gas having an unshared electron pair, an initial Ni film was formed, and then H ₂ gas was used as a reducing gas. Even if it is used, it is possible to form a Ni film thereon.
(2) When H ₂ is used as the reducing gas, since N is not taken into the film, a Ni film with high purity can be formed without forming Ni _x N.
(3) N contained in the initial Ni film can be removed by the presence of H ₂ gas which is a reducing gas.
(4) When using nickel amidinate as a film forming material and forming a Ni film on the initial Ni film using H ₂ as a reducing gas, a nickel amidinate and NH ₃ are used. The film formation rate is higher than the film formation.

  However, as a result of further investigation, when the method described in the above Japanese Patent Application No. 2011-1991917 is adopted, a main Ni film with high purity can be obtained in the main film forming step, but Ni contained in the initial Ni film is obtained. It has been found that impurities such as -N and Ni-C cannot be sufficiently removed, and such impurities deteriorate the specific resistance of the Ni film and cause nickel silicide formation failure.

Therefore, in the present embodiment, as described above, initial film formation is performed in Step 1 with nickel amidinate as a film formation raw material and NH ₃ as a reducing gas having an unshared electron pair, thereby generating nuclei (initial Ni After forming a film), the supply of nickel amidinate and NH ₃ gas is stopped as step 2 and hydrogen treatment is performed with H ₂ gas to remove impurities in the initial Ni film, and then step 3 is followed by nickel amidinate And H ₂ gas are used for main film formation. Thereby, the impurities in the initial Ni film are removed by the hydrogen treatment in step 2, and the main Ni film is formed as a film with very few impurities by reducing nickel amidinate with H ₂ gas. The obtained Ni film has a high purity with few impurities as a whole. Further, the hydrogen treatment in Step 2 only removes impurities in the very thin initial Ni film formed as nuclei, and may be a short-time treatment, and in the main film formation using H ₂ gas as the reducing gas, Since the film formation rate is higher than when NH ₃ gas is used, the throughput can be significantly increased as compared with the conventional method of forming a film using nickel amidinate and NH ₃ and annealing after the film formation.

The hydrogen treatment process of Step 2 is as follows: the pressure in the chamber 1: 333.3 to 13330 Pa (2.5 to 100 Torr), the heating temperature of the wafer W by the susceptor 2: 160 to 500 ° C., the H ₂ gas flow rate: 25 to 5000 mL / Min (sccm) is preferable. Also, the processing time depends on these conditions, but tens of seconds to several minutes is sufficient. Also, the pressure, temperature, and H ₂ gas flow rate are preferable because the larger the value in the above range, the higher the throughput.

In the initial film forming step of Step 1 above, the pressure in the chamber 1 is 133.3 to 2000 Pa (1 to 15 Torr), the heating temperature of the wafer W by the susceptor 2 (film forming temperature): 200 to 350 ° C., carrier Ar gas The flow rate is preferably 50 to 500 mL / min (sccm), and the NH ₃ gas flow rate is preferably 10 to 2000 mL / min (sccm).

Further, in the main film forming step of Step 3 above, the pressure in the chamber 1 is 133.3 to 2000 Pa (1 to 15 Torr), the heating temperature of the wafer W by the susceptor 2 (film forming temperature): 200 to 350 ° C., carrier Ar gas flow rate: 50 to 500 mL / min (sccm), H ₂ gas flow rate: 50 to 500 mL / min (sccm) are preferable.

  Further, when steps 1 to 3 are performed in the same chamber as in this embodiment, it is preferable to perform these steps at the same temperature and pressure from the viewpoint of increasing throughput. In addition, at least one of these steps 1 to 3 may be performed in a separate chamber, and in that case, conditions can be individually set in each step.

  When a Ni film is formed on a silicon substrate or polysilicon according to this embodiment, nickel silicide (NiSi) can be obtained by annealing in an inert gas atmosphere such as Ar gas after the film formation. In this case, since the Ni film with few impurities is obtained in this embodiment, the formation of nickel silicide does not occur, and the annealing process for silicidation can be performed in a short time.

Next, an experiment for confirming the effect of removing impurities by step 2 will be described.
Here, a sample in which a Ni film (corresponding to an initial Ni film) of about 30 nm is formed on a Si wafer using Ni (II) (tBu-AMD) ₂ as a film forming material and NH ₃ as a reducing gas. Then, after forming a Ni film in the same manner, a composition analysis in the film thickness direction was performed by X-ray photoelectron spectroscopy (XPS) on a sample which was supplied with H ₂ gas and subjected to hydrogen treatment. The results are shown in FIGS. In these figures, the horizontal axis indicates the etching cycle in the thickness direction, and etching is performed at about 1.7 nm by one etching. The hydrogen treatment was performed under the conditions of wafer temperature: 250 ° C., pressure: 1333 Pa (10 Torr), H ₂ gas flow rate: 500 mL / min (sccm), and treatment time: 180 sec.

  As a result, as shown in FIG. 4, when the Ni film is formed, N or C is contained in the film as impurities in total of 10 atomic% or more, whereas as shown in FIG. It was confirmed that N and C were almost removed by performing the above.

The present invention can be variously modified without being limited to the above embodiment. For example, in the above-described embodiment, a metal-containing material having a structure in which a film-forming raw material has a ligand having a nitrogen-carbon bond in a molecular structure and nitrogen in the ligand is coordinated to a metal. The case of forming a Ni film using Ni (II) (tBu-AMD) ₂ as a compound is exemplified, but other metals such as Ti (titanium), Co (cobalt), The present invention is also applicable when forming a metal film such as Cu (copper), Ru (ruthenium), Ta (tantalum), or the like. In particular, cobalt amidinate has the same structure as nickel amidinate. When a Co film is formed using cobalt amidinate, a nickel film is formed using the nickel amidinate. It is considered that the same effect as that obtained when the film is formed can be obtained. In addition, as a film forming raw material, when a Ni film is formed, other nickel amidinates can be used, and when forming other metals, various amidinate compounds can be used. it can. Further, any compound other than an amidinate compound may be used as long as it has a ligand having a nitrogen-carbon bond in the molecular structure and has a structure in which nitrogen in the ligand is coordinated to a metal.

  Further, the structure of the film forming apparatus is not limited to that in the above embodiment, and the method for supplying the film forming raw material is not necessarily limited to bubbling as in the above embodiment, and various methods can be applied.

  Furthermore, although the case where the semiconductor wafer was used as a to-be-processed substrate was demonstrated, not only this but another board | substrates, such as a flat panel display (FPD) board | substrate, may be sufficient.

1; chamber 2; susceptor 5; heater 10, showerhead to 30; the gas supply mechanism 31; film forming material tank 42; NH ₃ gas supply source 43; _{H 2} gas supply source 50; the control unit 51; the process controller 53; storage unit W: Semiconductor wafer

Claims (10)

A metal having a structure in which a substrate to be processed is arranged in a processing container, a ligand having a nitrogen-carbon bond in the molecular structure is formed on the substrate to be processed, and nitrogen in the ligand is coordinated to the metal. A first step of forming an initial metal film by CVD by supplying a film forming raw material comprising a compound and a reducing gas comprising at least one selected from ammonia, hydrazine, and derivatives thereof;
Then, a second step of supplying hydrogen gas into the processing vessel and performing hydrogen processing on the substrate to be processed;
From a metal-containing compound having a ligand having a nitrogen-carbon bond in the molecular structure and a structure in which nitrogen in the ligand is coordinated to the metal on the initial metal film formed on the substrate to be processed And a third step of forming a main metal film by CVD by supplying a reducing gas consisting of hydrogen gas and a film forming method for forming a metal film.   The metal film-forming method according to claim 1, wherein the metal-containing compound is a metal amidinate compound.   The metal film formation method according to claim 2, wherein the metal amidinate compound is nickel amidinate, and the metal film is a nickel film.   The method for forming a metal film according to claim 3, wherein the second step is performed at 160 to 500 ° C. 5.   5. The method for forming a metal film according to claim 3, wherein a pressure when performing the second step is 333 to 13330 Pa. 6.   The method for forming a metal film according to claim 3, wherein a hydrogen gas flow rate when performing the second step is 25 to 5000 mL / min (sccm). .   The method for forming a metal film according to any one of claims 3 to 6, wherein the first step and the third step are performed at 200 to 350 ° C.   The method for forming a metal film according to any one of claims 3 to 7, wherein a pressure when performing the first step and the third step is 133.3 to 2000 Pa. .   9. The method for forming a metal film according to claim 7, wherein the second step is performed at the same temperature and the same pressure as the first step and the third step.   A storage medium that operates on a computer and stores a program for controlling a film forming apparatus, wherein the program is executed when the metal film forming method according to any one of claims 1 to 9 is executed. A storage medium characterized by causing a computer to control the film forming apparatus.

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