JP4090346B2 - Semiconductor device manufacturing method and substrate processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device in which a thin film is formed on a substrate.
[0002]
[Prior art]
As one of the semiconductor manufacturing processes, there is a CVD (Chemical Vapor Deposition) process in which a predetermined film forming process is performed on the surface of a substrate (a substrate to be processed on which a fine electric circuit pattern based on silicon wafer or glass is formed). is there. This is because a substrate is loaded into an airtight reaction chamber, the substrate is heated by a heating means provided in the chamber, a chemical reaction occurs while introducing a film forming gas onto the substrate, and a fine electric circuit provided on the substrate. A thin film is uniformly formed on a pattern. In such a reaction chamber, the thin film is also formed on a structure other than the substrate. In the CVD apparatus shown in FIG. 19, a shower head 6 and a susceptor 2 are provided in a reaction chamber 1, and a substrate 4 is placed on the susceptor 2. The film forming gas is introduced into the reaction chamber 1 through the raw material supply pipe 5 connected to the shower head 6, and is supplied onto the substrate 4 through a large number of holes 8 provided in the shower head 6. The gas supplied onto the substrate 4 is exhausted through the exhaust pipe 7. The substrate 4 is heated by a heater 3 provided below the susceptor 2.
[0003]
As such a CVD apparatus, an organic chemical material is used as a film forming raw material, and amorphous HfO is used.₂There are MOCVD (Metal Organic Chemical Vapor Deposition) devices and ALD (Atomic Layer Deposition) devices for forming films and amorphous Hf silicate films (hereinafter simply referred to as HfO films). Here, the difference between the CVD method performed in the MOCVD apparatus and the ALD method performed in the ALD apparatus is as follows. In the ALD method, the processing temperature and pressure are low, and films are formed one atomic layer at a time. On the other hand, the CVD method has a higher processing temperature and pressure than the ALD method, and forms a film of approximately 1/6 atomic layer to several tens of atomic layers.
[0004]
As raw materials for film formation,
Hf [OC (CH_Three)_Three]_Four(Hereafter, Hf- (OtBu)_FourAbbreviated),
Hf [OC (CH_Three)₂CH₂OCH_Three]_Four(Hereafter, Hf- (MMP)_FourAbbreviated),
However, MMP: methyl methoxypropoxy
Hf [O-Si- (CH_Three]]_Four
Etc. are used.
[0005]
Among these, for example, Hf- (OtBu)_Four, Hf- (MMP)_FourMany organic materials are in a liquid phase at normal temperature and pressure. For this reason, for example, Hf- (MMP)_FourIs used after being heated and converted into gas by vapor pressure. Using such a raw material, an HfO film is formed, for example, at a substrate temperature of 450 ° C. or lower using the CVD method. This HfO film contains impurities such as CH and OH due to organic materials in a large amount of several percent. As a result, the category indicating the electrical properties of the substance belongs to a semiconductor or a conductor, contrary to the intention of securing an insulator.
[0006]
In order to ensure the electrical insulation of such a thin film and its stability, the HfO film is made of O₂Or N₂Attempts to convert C and H into dense and stable insulating thin films by applying high-speed annealing treatment (hereinafter abbreviated as RTA [Rapid Thermal Annealing]) at around 650 ° C. to 800 ° C. in an atmosphere. However, it has been performed conventionally. Here, the purpose of RTA is to remove impurities such as C and H in the film and to make them dense. Densification is not performed until crystallization, but is performed to reduce the average interatomic distance in the amorphous state.
[0007]
FIG. 20 shows a cluster device configuration in a conventional method for forming an HfO film. The substrate is carried into the load lock chamber 32 from the outside of the apparatus, subjected to substrate surface treatment such as RCA cleaning (a typical cleaning method based on hydrogen peroxide) in the first reaction chamber 33, and the second reaction chamber 34 described above. The HfO film is formed by the conventional equivalent method, RTA treatment (impurity removal, thermal annealing treatment) is performed in the third reaction chamber 35, and an electrode (poly-Si thin film or the like) is formed in the fourth reaction chamber 36. The substrate on which the electrodes are formed is carried out of the apparatus from the load lock chamber 32. The above carry-in / carry-out is performed using a substrate transfer robot 31 provided in the substrate transfer chamber 30.
[0008]
In the third reaction chamber 35, when C and H are separated from the HfO film by the RTA process, the surface state loses flatness and changes to an uneven surface state. In addition, the RTA treatment causes the HfO film to be partially crystallized, causing a large current to easily flow through the crystal grain boundary, resulting in a problem that the insulating property and its stability are impaired. These problems are common to the thin film deposition method using the MOCVD method or the ALD method using not only an insulator but also all organic chemical materials.
[0009]
In the second reaction chamber 34, a thin film is also formed on a structure other than the substrate. This is called a cumulative film, and a large amount of C and H is mixed in this cumulative film. For this reason, as the number of processed substrates increases, the amount of C and H released from the cumulative film increases, and the amount of C and H mixed in the HfO film formed on the substrate gradually increases as the number of processed substrates increases. Will do. This phenomenon makes it very difficult to keep the quality of continuously produced HfO films constant. In order to solve such a worrisome phenomenon, it is necessary to frequently perform a removal process of the accumulated film by self-cleaning, which is a factor of reducing productivity.
[0010]
As described above, in the conventional technique for forming an amorphous thin film, the surface state of the HfO film loses flatness due to the RTA process and changes to an uneven surface state, or the HfO film is partially crystallized to generate crystal grain boundaries. However, there has been a problem that insulation and stability thereof are lowered.
[0011]
Further, in order to make the quality of the continuously produced HfO film constant, it is necessary to frequently perform a cleaning process of the accumulated film in which a large amount of C and H is mixed, resulting in a decrease in productivity. was there.
[0012]
Although not related to the HfO film, as a thin film formation technique, Ta₂O_FiveA method of repeating film formation and reforming treatment a plurality of times in the same reaction chamber (see, for example, Patent Document 1), film formation of a high dielectric constant oxide film and a ferroelectric oxide film, and plasma generated using an oxidizing atmosphere gas A method of repeating the heat treatment used multiple times in the same reaction chamber (for example, see Patent Document 2) and a method of repeating the formation of a metal film and formation of a metal nitride film by introducing a nitriding agent gas (for example, see Patent Document 3). Are known.
[0013]
[Patent Document 1]
JP 2002-50622 A
[Patent Document 2]
JP-A-11-177057
[Patent Document 3]
JP-A-11-217672
[0014]
[Problems to be solved by the invention]
[0015]
However, even if it is going to form a metal oxide film using the prior art described in Patent Documents 1 to 3 described above, the metal oxide film is formed using a gas containing oxygen atoms in addition to the source gas during the film forming process. As a result, the specific element in the metal oxide film could not be effectively removed during the reforming step, and the film was not sufficiently reformed.
[0016]
In addition, since the film forming gas and the reactant are supplied from different supply ports, it is not possible to prevent foreign matter adhering to the inside of the supply port from falling onto the substrate, and even after cleaning, the inside of the supply port Removal of adsorbed by-products and cleaning gas was not sufficient.
[0017]
Further, when a thin film is formed with one apparatus and annealed, and then a substrate is taken out from one apparatus and an electrode is formed with another apparatus, there is a problem that throughput is lowered.
[0018]
An object of the present invention is to provide a method for manufacturing a semiconductor device capable of eliminating the above-described problems of the prior art and effectively removing a specific element in a metal oxide film during a reforming process. is there. Another object of the present invention is to prevent foreign matters adhering to the inside of the supply port from falling onto the substrate and to remove by-products and cleaning gas adsorbed inside the supply port by cleaning. Another object of the present invention is to provide a method for manufacturing a semiconductor device. It is another object of the present invention to provide a method for manufacturing a semiconductor device that can quickly remove a specific element in a film containing Hf. Furthermore, the subject of this invention is providing the manufacturing method of the semiconductor device which can improve a through-put.
[0019]
[Means for Solving the Problems]
A first invention uses a source gas obtained by vaporizing a source material containing oxygen atoms and metal atoms, and forms a metal oxide film on the substrate without using a gas containing oxygen atoms in addition to the source gas. The modification step of modifying the metal oxide film formed in the film formation step using a reactant different from the source gas is repeated a plurality of times in succession. In the film-forming process, a metal oxide film is formed on the substrate without using a gas containing oxygen atoms other than the source gas, so that the source containing oxygen atoms and metal atoms that easily contain specific elements in the film was vaporized. Even if the source gas is used, it is possible to easily remove the specific element in the film and easily modify the film. In addition, since the film forming process and the modifying process are continuously performed, the specific element in the film formed in the film forming process can be quickly removed to modify the film. In addition, since the film forming process and the modifying process are continuously repeated a plurality of times, it is possible to easily form a film having a predetermined film thickness and to perform the modifying process after forming a film having a predetermined film thickness at a time. In some cases, the removal amount of the specific element in the formed film can be increased to sufficiently modify the film.
[0020]
According to a second invention, in the first invention, the film forming step and the reforming step are performed in the same reaction chamber. When the film forming step and the reforming step are performed in the same reaction chamber, the temperature of the substrate is not lowered between the steps, so that the temperature raising time for processing the substrate again becomes unnecessary, and the temperature raising time of the substrate can be saved. Processing efficiency is good. In addition, since the substrate stops in the same reaction chamber, the film formation surface is hardly contaminated.
[0021]
According to a third invention, in the first invention, the metal atom is Hf, and the metal oxide film is a film containing Hf. When a raw material containing a metal atom is used as a raw material, a gas containing an oxygen atom such as an oxygen gas is usually used together. However, particularly when the metal atom is Hf and the metal oxide film is a film containing Hf, the oxygen atom is used. If no gas is used, the film can be modified by effectively removing specific elements in the film.
[0022]
In a fourth aspect based on the first aspect, the raw material is Hf [OC (CH_Three)₂CH₂0CH_Three]_FourThe metal oxide film is a film containing Hf. When an organic raw material is used as a raw material, a gas containing an oxygen atom is usually used together with Hf [OC (CH_Three)₂CH₂OCH_Three]_FourIn the case of using oxygen, it is possible to reduce the mixing amount of specific elements (impurities) such as C and H without using a gas containing oxygen atoms.
[0023]
According to a fifth invention, in the first invention, the metal atom is Hf, the metal oxide film is a film containing Hf, and the thickness of the metal oxide film formed in one film formation step is 0. .5 to 30 inches. When the film thickness of the Hf-containing film formed in one film formation process is 0.5 to 30 mm (1/6 atomic layer to 10 atomic layer), it is possible to maintain a state where crystallization is difficult even if impurities are included. By performing the modification treatment in this state, the film can be easily modified by removing impurities.
[0024]
A sixth invention is characterized in that, in the second invention, the source gas supplied to the substrate in the film forming step and the reactant supplied to the substrate in the reforming step are supplied from the same supply port. When the source gas supplied to the substrate in the film forming process and the reactant supplied to the substrate in the reforming process are supplied from the same supply port, the foreign matter adhering to the inside of the supply port may be covered and deposited with a metal oxide film. And foreign matter can be prevented from falling onto the substrate. Further, when the reaction chamber is cleaned with the cleaning gas, the by-product adsorbed inside the supply port and the cleaning gas can be removed.
[0025]
According to a seventh invention, in the second invention, the source gas supplied to the substrate in the film forming step and the reactant supplied to the substrate in the reforming step are supplied from separate supply ports, and the raw material is supplied in the film forming step. When supplying raw material gas to the substrate from the gas supply port, supply non-reactive gas to the reactant supply port, and when supplying reactant to the substrate from the reactant supply port in the reforming step The non-reactive gas is supplied to the supply port for the raw material gas. In this way, even if the source gas and the reactant are supplied from separate supply ports, and a non-reactive gas such as an inert gas is supplied from the supply ports not involved in each step, the inside of the supply port Cumulative film formation on the substrate can be suppressed.
[0026]
According to an eighth aspect of the present invention, in the second aspect, when supplying the source gas to the substrate in the film forming step, the reactant used in the reforming step is exhausted so as to bypass the reaction chamber without stopping. When the reactant is supplied to the substrate in the reforming step, the raw material gas used in the film forming step is exhausted so as to bypass the reaction chamber without stopping. As described above, if the reaction chamber is bypassed without stopping the supply of the reactant in the film formation process and the film formation gas in the reforming process, the film is immediately formed by simply switching the flow. Gases or reactants can be supplied to the substrate. Therefore, throughput can be improved.
[0027]
According to a ninth aspect, in the second aspect, the exhaust line for exhausting the reaction chamber in the film forming step and the exhaust line for exhausting the reaction chamber in the reforming step are provided with a trap used for both processes. Features. Since the trap is provided in the exhaust line, it is possible to reduce the inflow of the raw material to the exhaust pump and the abatement device that leads to the exhaust line, and to reduce the maintenance cycle of the device. In addition, since the trap is used for both processes, maintenance is simplified.
[0028]
According to a tenth aspect of the present invention, in the second aspect of the present invention, the method further includes a cleaning step of removing the film adhered in the reaction chamber using a cleaning gas activated by plasma, and the reactant used in the reforming step is activated by the plasma. The plasma source used for activating the gas in the reforming process and the plasma source used for activating the cleaning gas in the cleaning process are commonly used. Since the plasma source for reactant activation and cleaning gas activation is shared, the management of the plasma source is facilitated, and the semiconductor device can be manufactured at low cost.
[0029]
An eleventh invention is characterized in that, in the first invention, the reactant contains an oxygen atom. When the reactant contains oxygen atoms, the modification process of the specific element can be efficiently performed immediately after the formation of the metal oxide film.
[0030]
According to a twelfth aspect, in the first aspect, the reactant includes a gas obtained by activating a gas containing oxygen atoms with plasma. When the reactant is a gas in which a gas containing oxygen atoms is activated by plasma, the modification process of the specific element can be performed more efficiently immediately after the formation of the metal oxide film.
[0031]
A thirteenth invention is characterized in that, in the first invention, the film forming step and / or the modifying step is performed while rotating the substrate. Since the process is performed while rotating the substrate, the film can be modified by quickly and uniformly removing a specific element in the film.
[0032]
In a fourteenth aspect based on the second aspect, after the metal oxide film is formed on the substrate by repeating the film forming step and the modifying step, the substrate is exposed to the atmosphere from the reaction chamber through the transfer chamber without exposing the substrate to the atmosphere. As a process separate from the electrode formation process after forming the metal stopper film, the process has a process of transporting to the reaction chamber and a process of forming an electrode on the metal oxide film formed on the substrate in another reaction chamber. The electrode is formed without performing an annealing step, and the formation from the metal oxide film to the electrode formation is performed in the same apparatus. Since the formation from the metal oxide film to the electrode formation is performed in the same apparatus, it is possible to save time for heating the substrate as compared with the case where the electrode formation is performed by a different apparatus. In addition, the electrode can be formed while the surface of the film is clean. Further, since the metal oxide film is densified by thermal annealing performed at the time of electrode formation, the film is hardly contaminated.
[0033]
According to a fifteenth aspect of the present invention, a film forming process for supplying a film forming gas onto a substrate to form a thin film, and a reactant different from the film forming gas is supplied to modify the thin film formed in the film forming process. In the method for manufacturing a semiconductor device, in which the reforming process is repeated in the same reaction chamber a plurality of times, the film forming gas supplied to the substrate in the film forming process and the reactant supplied to the substrate in the reforming process are the same. It is characterized by being supplied from a supply port. Since the film forming step and the modifying step are performed continuously, the specific element in the film formed in the film forming step can be quickly removed to modify the film. In addition, since the film forming step and the modifying step are repeated a plurality of times in succession, a film having a predetermined film thickness can be easily formed, and a film having a predetermined film thickness is formed at a time and then the modifying step is performed. In some cases, the film can be modified by increasing the removal amount of the specific element in the formed film. In addition, if the source gas supplied to the substrate in the film formation process and the reactant supplied to the substrate in the reforming process are supplied from the same supply port, the foreign matter adhering to the inside of the supply port may be covered with a thin film and deposited. And foreign matter can be prevented from falling onto the substrate. Further, when the reaction chamber is cleaned with the cleaning gas, the by-product adsorbed inside the supply port and the cleaning gas can be removed.
[0034]
According to a sixteenth aspect of the present invention, a film forming step for forming a film containing Hf on a substrate using a source gas obtained by vaporizing a source material containing Hf and a film forming step using a reactant different from the source gas are used. The modification step of modifying the film containing Hf is repeatedly performed a plurality of times. Since the film formation process and the modification process are performed continuously, the specific element in the film containing Hf formed in the film formation process can be quickly removed to modify the film. In addition, since the film forming process and the reforming process are repeated a plurality of times in succession, a film containing Hf having a predetermined film thickness can be easily formed, and a film containing Hf having a predetermined film thickness can be formed at a time. In contrast to the case where the modification step is performed, it is possible to modify the film containing Hf by increasing the removal amount of the specific element in the formed film.
[0035]
According to a seventeenth aspect, in the sixteenth aspect, the film thickness of the Hf-containing film formed in one film formation step is 0.5 to 30 mm. When the film thickness of the Hf-containing film formed in one film formation process is 0.5 to 30 mm, that is, 1/6 atomic layer to 10 atomic layer, it is possible to maintain a state where it is difficult to crystallize even if there is an impurity, By performing the reforming treatment in this state, impurities can be removed and the film can be easily modified.
[0036]
According to an eighteenth aspect of the present invention, a film forming process for supplying a film forming gas onto a substrate to form a thin film, and a reactant different from the film forming gas is supplied to reform the thin film formed in the film forming process. A process of forming a thin film on a substrate by repeating the reforming step multiple times in the same reaction chamber, and then transporting the substrate from the reaction chamber to another reaction chamber without exposing the substrate to the atmosphere; Forming the electrode on the thin film formed on the substrate in another reaction chamber, and forming the electrode without performing an annealing process as a separate process from the electrode forming process after the thin film is formed. The process from the formation to the electrode formation is performed in the same apparatus. Since the thin film formation, the thin film modification, and the electrode formation are performed in the same apparatus, the time required for heating the substrate can be saved as compared with the case where the thin film modification and the electrode formation are performed by different apparatuses. Moreover, the specific element in the film can be quickly removed to modify the film, and the electrode can be formed while the surface of the thin film is in a clean state. Further, since the thin film is densified by thermal annealing performed at the time of electrode formation, the thin film is hardly contaminated.
[0037]
According to a nineteenth aspect of the invention, there is provided a reaction chamber for processing a substrate, a first supply port for supplying a raw material gas obtained by vaporizing a raw material containing oxygen atoms and metal atoms into the reaction chamber, and a reaction different from the gas in the reaction chamber. A second supply port for supplying an object and an exhaust port for exhausting the reaction chamber, and forming a metal oxide film on the substrate without using a gas containing oxygen atoms in addition to the source gas in the reaction chamber And a control device for controlling a film forming process to be performed and a reforming process for modifying the metal oxide film formed in the film forming process using a reactant different from the source gas so as to be repeated a plurality of times. A substrate processing apparatus. By having a control device that controls the film forming process and the reforming process to be repeated a plurality of times in succession, the above-described method for manufacturing a semiconductor device can be easily implemented.
[0038]
In the first to second inventions, the sixth to fifteenth inventions, the eighteenth and nineteenth inventions described above, the film formed in the film forming step is not limited to a film containing Hf. In 3rd invention-5th invention, 16th invention-17th invention, the film | membrane formed at the film-forming process is limited to the film | membrane containing Hf. As an example of a film containing Hf, HfO₂HfON, HfSiO, HfSiON, HfAlO, HfAlON, and the like. Examples of films other than films containing Hf include the following.
PET (Ta (OC₂H_Five)_Five) Using TaO film (tantalum oxide film)
Zr- (MMP)_FourZrO film (zirconium oxide film)
Al- (MMP)_ThreeAlO film using aluminum (aluminum oxide film)
Zr- (MMP)_FourAnd Si- (MMP)_FourZrSiO film (oxidized Zr silicate film) and ZrSiON film (oxynitride Zr silicate film)
Zr- (MMP)_FourAnd Al- (MMP)_ThreeZrAlO film and ZrAlON film using
Ti- (MMP)_FourTiO film using titanium (titanium oxide film)
Ti- (MMP)_FourAnd Si- (MMP)_FourTiSiO and TiSiON films using
Ti- (MMP)_FourAnd Al- (MMP)_ThreeTiAlO and TiAlON films using
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In the embodiment, by using the CVD method, more specifically, the MOCVD method, the HfO film is particularly HfO in an amorphous state.₂Membrane (hereinafter simply referred to as HfO₂The case of forming a film is abbreviated.
[0040]
FIG. 1 is a schematic view showing an example of a single wafer CVD apparatus which is a substrate processing apparatus according to an embodiment. Compared to the conventional reaction chamber 1 (FIG. 19), a reactant activation unit 11, a substrate rotation unit 12, an inert gas supply unit 10, and a bypass pipe 14 as plasma sources are mainly added.
[0041]
As shown in the figure, a hollow heater unit 18 whose upper opening is covered with a susceptor 2 is provided in the reaction chamber 1. The heater 3 is provided inside the heater unit 18, and the substrate 4 placed on the susceptor 2 is heated by the heater 3. The substrate 4 placed on the susceptor 2 is, for example, a semiconductor silicon wafer or glass.
[0042]
A substrate rotation unit 12 is provided outside the reaction chamber 1, and the substrate unit 4 on the susceptor 2 can be rotated by rotating the heater unit 18 in the reaction chamber 1 by the substrate rotation unit 12. The reason why the substrate 4 is rotated is to quickly and uniformly perform processing on the substrate in a film forming process and a modifying process described later.
[0043]
A shower head 6 having a large number of holes 8 is provided above the susceptor 2 in the reaction chamber 1. A raw material supply pipe 5 for supplying a film forming gas and a radical supply pipe 13 for supplying a radical are commonly connected to the shower head 6, so that the film forming gas or the radical is discharged from the shower head 6 in a shower shape. It can be ejected inward. Here, the shower head 6 constitutes the same supply port for supplying a film forming gas supplied to the substrate 4 in the film forming process and a radical supplied to the substrate 4 in the modifying process.
[0044]
A film forming material supply unit 9 for supplying an organic liquid material as a film forming material to the outside of the reaction chamber 1, a liquid flow rate control device 28 as a flow rate control means for controlling the liquid supply flow rate of the film forming material, and a film forming material And a vaporizer 29 is provided. An inert gas supply unit 10 for supplying an inert gas as a non-reactive gas and a mass flow controller 46 as a flow rate control means for controlling the supply flow rate of the inert gas are provided. Hf- (MMP) as a film forming material_FourUse organic materials such as In addition, as the inert gas, Ar, He, N₂Etc. are used. A raw material supply pipe 5 b provided in the film forming raw material supply unit 9 and an inert gas supply pipe 5 a provided in the inert gas supply unit 10 are integrated into a raw material supply pipe connected to the shower head 6. 5 is provided. The raw material supply pipe 5 is formed on the substrate 4 with HfO.₂In the film forming process for forming a film, a mixed gas of a film forming gas and an inert gas is supplied to the shower head 6. The source gas supply pipe 5b and the inert gas supply pipe 5a are respectively provided with valves 21 and 20, and by opening and closing these valves 21 and 20, the supply of the mixed gas of the film forming gas and the inert gas is controlled. It is possible.
[0045]
In addition, a reactant activation unit (remote plasma unit) 11 serving as a plasma source that activates gas with plasma and forms radicals as reactants is provided outside the reaction chamber 1. The radical used in the reforming process is Hf- (MMP) as a raw material._FourIn the case of using an organic material such as, oxygen radicals are preferable, for example. This is due to oxygen radicals and HfO₂This is because the removal of impurities such as C and H can be performed efficiently immediately after the film formation. The radical used in the cleaning process is ClF._ThreeA radical is good. In the reforming process, an oxygen-containing gas (O₂, N₂The process of oxidizing the film in an oxygen radical atmosphere in which O, NO, etc.) are decomposed by plasma is called remote plasma oxidation (RPO) process.
[0046]
A gas supply pipe 37 is provided on the upstream side of the reactant activation unit 11. The gas supply pipe 37 has oxygen (O₂), An Ar supply unit 48 for supplying argon (Ar) as a gas for generating plasma, and chlorine fluoride (ClF)._Three) To supply ClF_ThreeA supply unit 49 is connected via supply pipes 52, 53, and 54 and is used in the reforming process.₂And Ar, and ClF used in the cleaning process_ThreeIs supplied to the reactant activation unit 11. Oxygen supply unit 47, Ar supply unit 48, and ClF_ThreeThe supply unit 49 is provided with mass flow controllers 55, 56, and 57 as flow rate control means for controlling the supply flow rates of the respective gases. The supply pipes 52, 53, and 54 are provided with valves 58, 59, and 60, respectively, and by opening and closing these valves 58, 59, and 60, O₂Gas, Ar gas, and ClF_ThreeCan be controlled.
[0047]
A radical supply pipe 13 connected to the shower head 6 is provided on the downstream side of the reactant activation unit 11 so as to supply oxygen radicals or chlorine fluoride radicals to the shower head 6 in a reforming process or a cleaning process. It has become. Further, the radical supply pipe 13 is provided with a valve 24, and the supply of radicals can be controlled by opening and closing the valve 24.
[0048]
An exhaust port 7a is provided in the reaction chamber 1, and the exhaust port 7a is connected to an exhaust pipe 7 that communicates with a detoxifying device (not shown). The exhaust pipe 7 is provided with a raw material recovery trap 16 for recovering the film forming raw material. This raw material recovery trap 16 is used in common for the film forming process and the reforming process. The exhaust port 7a and the exhaust pipe 7 constitute an exhaust line.
[0049]
Further, the source gas supply pipe 5b and the radical supply pipe 13 include a source gas bypass pipe 14a and a radical bypass pipe 14b connected to a source recovery trap 16 provided in the exhaust pipe 7 (these may be simply referred to as a bypass pipe 14). Are provided). Valves 22 and 23 are provided in the source gas bypass pipe 14a and the radical bypass pipe 14b, respectively. When the film formation gas is supplied to the substrate 4 in the reaction chamber 1 in the film formation process by opening and closing these valves, the radicals used in the reforming process are bypassed without stopping the supply of radicals used in the reforming process. It exhausts through the bypass pipe 14b and the raw material collection | recovery trap 16. Further, when supplying radicals to the substrate 4 in the reforming step, the source gas bypass pipe 14a and the source recovery trap 16 are provided so as to bypass the reaction chamber 1 without stopping the supply of the deposition gas used in the deposition step. Exhaust through.
[0050]
Then, HfO on the substrate 4 in the reaction chamber 1₂Film formation process for forming a film and HfO formed in the film formation process₂A modification step of removing impurities such as C and H, which are specific elements in the film, by plasma treatment using the reactant activation unit 11 is continued by controlling the opening and closing of the valves 20 to 24. And a control device 25 is provided for controlling to repeat a plurality of times.
[0051]
Next, using the single-wafer CVD apparatus configured as shown in FIG. 1 described above, high-quality HfO different from the conventional one is used.₂The procedure for depositing the film is shown. This procedure includes a temperature raising process, a film forming process, a purge process, and a reforming process.
[0052]
First, the substrate 4 is placed on the susceptor 2 in the reaction chamber 1 shown in FIG. Heat uniformly to ° C. (temperature raising step). The substrate temperature depends on the reactivity of the organic material used, but Hf- (MMP)_FourIn the range of 390 to 450 ° C. is preferable. Further, when the substrate 4 is transported or heated, the valve 20 provided in the inert gas supply pipe 5a is opened, and Ar, He, N₂When an inert gas such as is constantly flowed, particles and metal contaminants can be prevented from adhering to the substrate 4.
[0053]
After the temperature raising process, the film forming process is started. In the film forming step, the organic liquid raw material supplied from the film forming raw material supply unit 9, for example, Hf- (MMP)_FourIs controlled by the liquid flow control device 28 and supplied to the vaporizer 29 for vaporization. By opening the valve 21 provided in the source gas supply pipe 5b, the evaporated source gas is supplied onto the substrate 4 via the shower head 6. Also at this time, the inert gas (N₂Etc.) is constantly flown so that the film forming gas is stirred. When the film forming gas is diluted with an inert gas, it becomes easy to stir. The film forming gas supplied from the raw material gas supply pipe 5b and the inert gas supplied from the inert gas supply pipe 5a are mixed in the raw material supply pipe 5 and led to the shower head 6 as a mixed gas. It is supplied in a shower form onto the substrate 4 on the susceptor 2 via the hole 8. At this time, O₂Gas containing oxygen atoms such as Hf- (MMP) is used as the reactive gas._FourSupply only gas.
[0054]
By supplying the mixed gas for a predetermined time, HfO as an interface layer (first insulating layer) with the substrate is formed on the substrate 4.₂The film is formed from 0.5 to 30 inches, for example, 15 inches. During this time, since the substrate 4 is kept at a predetermined temperature (film formation temperature) by the heater 3 while rotating, a uniform film can be formed over the substrate surface. Next, the valve 21 provided in the source gas supply pipe 5b is closed, and the supply of the source gas to the substrate 4 is stopped. At this time, the valve 22 provided in the source gas bypass pipe 14a is opened, and the supply of the film forming gas is exhausted by bypassing the reaction chamber 1 with the source gas bypass pipe 14a. Do not stop the gas supply. Since it takes time to vaporize the liquid raw material and stably supply the vaporized raw material gas, if the reaction chamber 1 is allowed to flow without stopping the supply of the film forming gas, the following formation is performed. In the film process, the film forming gas can be immediately supplied to the substrate 4 simply by switching the flow.
[0055]
After the film formation process is completed, the purge process is started. In the purge step, the inside of the reaction chamber 1 is purged with an inert gas to remove residual gas. Note that the valve 20 is kept open in the film forming step, and the inert gas (N₂Etc.) is always flowing, the valve 21 is closed and the supply of the source gas to the substrate 4 is stopped, and at the same time, the purge is performed.
[0056]
After the purge process, the reforming process is started. The reforming step is performed by RPO (remote plasma oxidation) treatment. Here, the RPO treatment means an oxygen-containing gas (O₂, N₂O, NO, etc.) is a remote plasma oxidation process in which a film is oxidized by using oxygen radicals as reactants generated by activation of plasma. In the reforming step, the valve 59 provided in the supply pipe 53 is opened, the flow rate of Ar supplied from the Ar supply unit 48 is controlled by the mass flow controller 56 and supplied to the reactant activation unit 11 to generate Ar plasma. After generating the Ar plasma, the valve 58 provided in the supply pipe 52 is opened, and the O supplied from the oxygen supply unit 47 is opened.₂Is supplied to the reactant activation unit 11 generating Ar plasma by controlling the flow rate with the mass flow controller 55,₂Activate. Thereby, oxygen radicals are generated. A valve 24 provided in the radical supply pipe 13 is opened, and a gas containing oxygen radicals is supplied from the reactant activation unit 11 onto the substrate 4 through the shower head 6. During this time, the substrate 4 is kept at a predetermined temperature (the same temperature as the film formation temperature) by the heater 3 while rotating, so that 15% HfO formed on the substrate 4 in the film formation process.₂Impurities such as C and H can be quickly and uniformly removed from the film.
[0057]
Thereafter, the valve 24 provided in the radical supply pipe 13 is closed to stop the supply of oxygen radicals to the substrate 4. At this time, by opening the valve 23 provided in the radical bypass pipe 14b, the supply of the gas containing oxygen radicals is exhausted by bypassing the reaction chamber 1 with the radical bypass pipe 14b, and the supply of oxygen radicals is not stopped. Like that. Since oxygen radicals take a long time to be stably supplied after generation, if the reaction chamber 1 is allowed to bypass without stopping the supply of oxygen radicals, the flow is simply switched in the next reforming step. Immediately, radicals can be supplied to the substrate 4.
[0058]
After the reforming step, the purge step is started again. In the purge step, the inside of the reaction chamber 1 is purged with an inert gas to remove residual gas. Note that the valve 20 remains open even in the reforming process, and the inert gas (N₂Etc.) is always flowing, so that purging is performed simultaneously with stopping the supply of oxygen radicals to the substrate 4.
[0059]
After the purge process, the film forming process is started again, the valve 22 provided in the source gas bypass pipe 14a is closed, and the valve 21 provided in the source gas supply pipe 5b is opened, so that the film forming gas passes through the shower head 6. Supplied onto the substrate 4 and 15 liters of HfO.₂A film is deposited on the thin film formed in the previous film formation step.
[0060]
As described above, a thin film having a predetermined film thickness with very little mixing of CH and OH can be formed by the cycle process in which the film forming process → the purge process → the reforming process → the purge process is repeated a plurality of times.
[0061]
Where Hf- (MMP)_FourThe preferable film formation conditions when using is as follows. The temperature range is 400 to 450 ° C., and the pressure range is about 100 Pa or less. Regarding the temperature, when the temperature is lower than 400 ° C., the amount of impurities (C, H) taken into the film increases rapidly. When the temperature is higher than 400 ° C., the impurities are easily detached and the amount of impurities taken into the film is reduced. Moreover, although step coverage will worsen when it becomes higher than 450 degreeC, when it is the temperature of 450 degrees C or less, favorable step coverage will be obtained and an amorphous state can also be maintained.
[0062]
As for the pressure, for example, if the pressure is higher than 1 Torr (133 Pa), the gas becomes a viscous flow, and the gas does not enter into the pattern groove. However, by setting the pressure to about 100 Pa or less, a molecular flow without a flow can be obtained, and the gas reaches the depth of the pattern groove.
[0063]
Hf- (MMP)_FourThe preferable conditions for the RPO (remote plasma oxidation) process, which is a reforming process that is performed continuously after the film forming process using, are a temperature range of about 390 to 450 ° C. (approximately the same temperature as the film forming temperature), and a pressure range of 100. It is about ~ 1000Pa. O for radicals₂The flow rate is 100 sccm, and the inert gas Ar flow rate is 1 slm.
[0064]
The film forming step and the reforming step are preferably performed at substantially the same temperature (the heater set temperature is preferably kept constant without being changed). This is because, by not causing temperature fluctuation, particles due to thermal expansion of peripheral members such as a shower head and a susceptor are less likely to be generated, and metal jump-out (metal contamination) from metal parts can be suppressed.
[0065]
In order to carry out the self-cleaning process of the accumulated film with the cleaning gas radicals, the cleaning gas (Cl₂And ClF_ThreeEtc.) are introduced into the reaction chamber 1 as radicals. By this self-cleaning, the cleaning gas and the accumulated film are reacted in the reaction chamber 1, and the accumulated film is converted into metal chloride and volatilized, and then exhausted. Thereby, the accumulated film in the reaction chamber is removed.
[0066]
According to the embodiment described above, HfO₂Film formation → Reforming treatment (RPO treatment) → HfO₂Since a cycle process of repeating film formation →... Multiple times is performed, HfO having a predetermined film thickness with very little mixing of CH and OH.₂A film can be formed. Hereinafter, this will be specifically described from the following viewpoint.
(1) O during film formation₂Not used
(2) RPO processing
(3) Cycle processing
(4) Rotation mechanism
(5) Sharing the shower head
(6) Bypass pipe
(7) Trap sharing
(8) Use of plasma source
(9) Processing performed in the same device
(10) Modification
[0067]
(1) O during film formation₂Not used
HfO in film formation process₂At the time of film formation, oxygen (O₂If the gas containing oxygen atoms such as) is not used, the amount of CH and OH mixed in the film can be reduced.
[0068]
HfO₂When forming the film, O in the mixed gas of the source gas and the inert gas.₂There are cases where these are mixed. In consideration of the adhesion to the substrate and the film formation rate, this is generally O together with the source gas.₂It is because it is better to put. However, the inventors have found that Hf- (MMP)_FourAbout O₂If not, the amount of impurities is reduced and the film quality is improved.₂It has been found that the amount of impurities increases and the film quality deteriorates with the addition of. Therefore, Hf- (MMP)_FourIn the embodiment using O,₂If not mixed, the amount of CH and OH in the film can be reduced.₂Not mixed.
[0069]
Hf- (MMP)_FourThe mechanism that can reduce the amount of impurities mixed when oxygen is not supplied is as follows. Hf- (MMP)_FourComparison of ideal chemical reaction formulas when oxygen is mixed using oxygen (hereinafter also referred to as oxygen) and when oxygen is not mixed (hereinafter also referred to as no oxygen) is as follows.
[0070]
A. When an ideal reaction occurs without oxygen (ideal self-decomposition reaction with heat alone):
Hf [OC (CH_Three)₂CH₂OCH_Three]_Four→ Hf (OH)_Four+ 4C (CH_Three)₂CH₂OCH₂↑ (1)
Hf (OH)_Four→ HfO₂+ 2H₂O (2)
B. If an ideal reaction occurs with oxygen (complete combustion):
Hf [OC (CH_Three)₂CH₂OCH_Three]_Four+ 24O₂→ HfO₂+ 16CO₂↑ + 22H₂O ↑ (3)
However, ↑ means a volatile substance.
In the above reaction chemical formula, the numerical value in upper case is considered as the molar ratio of the raw material on the substrate as it is, without oxygen,
HfO₂: (Other impurities) = 1: (4 + 2) = 1: 6
It becomes. With oxygen,
HfO₂: (Other impurities) = 1: (16 + 22) = 1: 38.
[0071]
Thus, 1 mole of HfO₂The total number of moles of impurities generated when producing oxygen is larger when oxygen is present.
[0072]
Furthermore, when comparing the number of cleavages in the chemical formula for breaking each bond,
Without oxygen: O-C, C-H, and O-H cut 4 times each, 12 times in total
With oxygen: OC 12 times, CH 44 times, total 56 times
As the number of times of cutting increases, the amount of radicals increases, so that impurities are easily mixed into the film.
[0073]
As a conclusion, the film was formed without oxygen, and [C (CH_Three)₂CH₂OCH_ThreeIs volatilized at a temperature that does not cause decomposition, and HfO₂A film may be formed.
[0074]
Also, using FTIR (Fourier transform infrared spectroscopy), O₂From FIG. 2 and FIG. 3 in which the influence on the thin film by the addition amount was measured, HfO was obtained without oxygen.₂It is confirmed that it is preferable to form a film.
[0075]
FIG. 2 shows the film quality characteristics of the thin film compared with and without oxygen. Wave number (cm on the horizontal axis^-1), And the vertical axis indicates the absorbance at film formation temperatures of 425 ° C. and 440 ° C. When oxygen is present, the oxygen flow rate is 0.5 SLM. As shown in the figure, in particular, the wave number is 752 cm.^-1By exciting a nearby stretch mode, the absorbance reflecting the X—O—X bond indicating Hf—O—Hf bond is greater in the absence of oxygen than in the presence of oxygen. In other words, the film quality is better in the case of no oxygen.
[0076]
FIG. 3 shows the characteristics of the amount of impurities contained in the film compared with and without oxygen. Wave number (cm on the horizontal axis^-1), And the vertical axis indicates the absorbance at film formation temperatures of 425 ° C. and 440 ° C. When oxygen is present, the oxygen flow rate is 0.5 SLM. As shown in the figure, when the stretch and wagging modes are excited, the absorbance reflecting the amount of impurities (—OH, C—H, C—O) is absent when oxygen is present. It was found that the film formation with oxygen was about five times as large as the film formation without oxygen. This indicates that the case of no oxygen has a smaller amount of impurities and better film quality. Therefore, HfO₂During film formation, O₂Without using, the amount of CH and OH in the film can be reduced, and the film can be sufficiently modified. In the present invention, O₂This is not to exclude the existence at all.₂A small amount of O that is not substantially different from the case of not introducing₂In this case, the film can be sufficiently modified.
[0077]
Here, the relationship with the present invention will be described with respect to each film forming mechanism and temperature zone using the self-decomposition reaction, semi-self-decomposition reaction, and adsorption reaction of the raw material. All CVD reactions are in a state where self-decomposition reaction and adsorption reaction overlap. If the substrate temperature is lowered, the adsorption reaction becomes dominant, and if the temperature is raised, the self-decomposition reaction becomes dominant. A semi-self-decomposing reaction also occurs at an intermediate temperature. Hf- (MMP)_FourIn the case of using, it is considered that the adsorption reaction is mainly performed at 300 ° C. or lower, and that the self-decomposition reaction is mainly performed at a higher temperature. However, the adsorption reaction is not completely eliminated at any temperature range. Hf- (MMP)_FourThe reaction formula of the self-decomposition reaction is as shown in the above formulas (1) and (2). Moreover, Hf- (MMP) is formed on the substrate by an adsorption reaction._FourThe reaction formula for causing a film-forming reaction by adsorbing and oxidizing by RPO treatment or the like is Hf- (MMP) in the above gas phase._FourAnd O₂Is the same as in the case of the reaction (gas phase reaction), as in the above formula (3). In the MOCVD according to the present invention, the effect of removing impurities by RPO can be obtained regardless of which of the above reactions is dominant, so that the reaction mode is not particularly specified. The experimental result that it can do less is obtained.
[0078]
(2) RPO processing
By the RPO treatment used in the reforming step after the film formation, impurities such as hydrogen (H) and carbon (C) in the film can be effectively removed and the concentration can be reduced, so that the electrical characteristics can be improved. Moreover, the movement of Hf atoms is suppressed by the separation of hydrogen (H), crystallization can be prevented, and electrical characteristics can be improved. In addition, oxidation of the film can be promoted, and oxygen defects in the film can be repaired. In addition, the detached gas from the accumulated film deposited on portions other than the substrate such as the reaction chamber wall and the susceptor can be quickly reduced, and the film thickness can be controlled with high reproducibility.
[0079]
In the embodiment, the RPO process is used in the reforming step, but the present invention is not limited to this. As an alternative to the RPO treatment (<1> below), for example, there are the following (<2> to <8> below).
(1) O in inert gas (Ar)₂RPO treatment performed by mixing
▲ 2 ▼ Ar to N₂RPN processing performed by mixing
(3) Ar to N₂And H₂RPNH treatment performed by mixing
▲ 4 ▼ Ar to H₂RPH treatment performed by mixing
▲ 5 ▼ Ar to H₂RPOH treatment by mixing O
▲ 6 ▼ Ar to O₂And H₂RPOH treatment with mixing
▲ 7 ▼ Ar to N₂RPON processing by mixing O
▲ 8 ▼ Ar to N₂And O₂RPON processing by mixing
[0080]
In the embodiment, HfO is used in the same reaction chamber.₂Film formation and RPO treatment are performed, and the merits are as follows. HfO₂When a film is formed, HfO is also applied to the reaction chamber wall, shower head, susceptor, etc.₂A film is formed. This is called a cumulative film. HfO without RPO treatment when performed in separate reaction chambers₂In the membrane reaction chamber, C and H come out from the accumulated film and the reaction chamber is contaminated. Further, the amounts of C and H coming out of the accumulated film increase as the thickness increases. Therefore, it is difficult to keep the C and H amounts of all the substrates to be processed constant.
[0081]
In contrast, HfO₂When film formation and RPO treatment are performed in the same reaction chamber, C and H can be removed not only from C and H in the film formed on the substrate but also from the accumulated film deposited in the reaction chamber (cleaning). Effect), C and H contents can be made constant for all substrates.
[0082]
(3) Cycle processing
By the cycle treatment, the impurity removal efficiency in the film can be improved as described above. Further, the film can be maintained in an amorphous state, and as a result, leakage current can be reduced. Further, the flatness of the film surface can be improved, and the film thickness uniformity can be improved. In addition, the film can be densified (maximization of defect repair effect) and the deposition rate can be precisely controlled. Furthermore, an undesired interface layer formed at the interface between the film formation base and the deposited film can be thinned.
[0083]
HfO formed by cycle treatment₂The amounts of C and H impurities contained in the film (for example, a film thickness of 10 nm) can be significantly reduced as the number of cycles increases as shown in FIG. The horizontal axis indicates the number of cycles, and the vertical axis indicates the total amount of C and H (arbitrary units). When the number of cycles is 1, this corresponds to the conventional method.
[0084]
According to FIG. 4, HfO formed by cycle processing.₂When the total film thickness is 10 nm (100 mm), HfO such as CH and OH is required in about 3 cycles.₂Since the effect of reducing the amount of impurities in the film is increased, the film thickness per cycle is preferably about 30 mm or less. In CVD, since the film thickness that can be formed by one film formation is about 0.5 mm, the film thickness per cycle is preferably 0.5 mm to 30 mm. In particular, HfO such as CH and OH in about 7 cycles.₂The effect of reducing the amount of impurities in the film becomes extremely large, and even if the number of cycles is increased further, the effect of reducing the amount of impurities is slightly improved, but there is no significant change, so the film thickness per cycle is about 15 mm (5% Atomic layer) is considered more preferred. When depositing more than 30 liters in one cycle, the impurities in the film increase, and it instantly crystallizes into a polycrystalline state. Since the polycrystalline state is a state with no gap, it becomes difficult to remove C, H, and the like. However, when the film thickness formed by one cycle is less than 30 mm, it becomes difficult to form a crystallized structure, and the thin film can be maintained in an amorphous state even if there are impurities. Since the amorphous state has many gaps (scalar state), the thin film is deposited while maintaining the amorphous state, and RPO treatment is performed before the thin film crystallizes to remove impurities such as C and H in the film. It becomes easy to do. That is, a film obtained by a plurality of cycle treatments with a film thickness per cycle of about 0.5 to 30 mm is hardly crystallized. Note that the amorphous state has an advantage that leakage current is less likely to flow than the polycrystalline state.
[0085]
HfO₂HfO by repeating film formation → RPO process multiple times₂The reason why the removal efficiency of impurities in the film can be increased is as follows. HfO formed with good coverage for deep pattern grooves₂When performing RPO treatment (modification treatment of C, H, etc.) on the membrane, HfO at a time₂If the RPO process is performed after forming a thick film, for example, 100 Å, oxygen radicals are difficult to be supplied to the depth b of the groove in FIG. This is because the probability that the oxygen radicals will react with C and H at the surface a in FIG. 5 in the process of reaching the depth b of the groove (thickness is as large as 100 mm and the amount of impurities is large accordingly). This is because the amount of radicals that reach the depth b of the groove relatively decreases. Therefore, it becomes difficult to perform uniform C and H removal in a short time.
[0086]
In contrast, 100mm HfO₂In forming the film, HfO₂When the film formation → RPO process is performed in 7 steps, the RPO process is performed with HfO per 15%.₂It is only necessary to perform the C and H removal process only on the film. In this case, since the probability that oxygen radicals react with C and H in the region of the plane a in FIG. 5 does not increase (because the film thickness is as small as 15 mm and the amount of impurities is small correspondingly), it is evenly distributed in the depth b of the groove. A radical will arrive. Therefore, HfO₂By repeating the film formation → RPO process a plurality of times, uniform C and H removal can be performed in a short time.
[0087]
Furthermore, by performing a cycle process in which the film formation process and the reforming process are repeated a plurality of times in succession, the amount of impurities such as C and H contained in the accumulated film deposited in the reaction chamber can be greatly reduced. Since the desorption gas from the accumulated membrane can be greatly reduced, continuously produced HfO₂The film quality can be kept constant. Therefore, it is not necessary to frequently perform the removal process of the accumulated film by self-cleaning as compared with the conventional case, and the production cost can be reduced.
[0088]
(4) Rotation mechanism
In the embodiment, since the substrate 4 is rotated by the substrate rotating unit 12, the source gas introduced from the film forming source supply unit and the gas activated by the plasma as the reactant introduced from the reactant activation unit 11 ( (Hereinafter referred to as radicals) can be quickly and uniformly distributed within the substrate surface, and the film can be uniformly deposited over the substrate surface, and impurities in the film can be quickly and uniformly removed within the substrate surface. Can be modified.
[0089]
(5) Sharing the shower head
When a film forming gas supplied to the substrate in the film forming process and a radical as a reactant supplied to the substrate in the reforming process are supplied from the shower head 6 serving as the same supply port, foreign matter (inside the shower head 6 ( Particle source) HfO₂The film can be covered and coated, and foreign matter can be prevented from falling onto the substrate 4. Further, the film coated inside the shower head is exposed to the reaction product after coating, whereby the amount of impurities such as C and H contained in the coating film inside the shower head can be greatly reduced. Also, the reaction chamber 1 is ClF_ThreeWhen cleaning with a gas containing Cl such as by-products or cleaning gas remaining in the reaction chamber 1 or the shower head 6 is adsorbed (this is referred to as cleaning residue), supply of source gas and reactant By sharing the mouth, this cleaning residue can be effectively removed. .
[0090]
(6) Bypass pipe
In the embodiment, a bypass pipe 14 (14a, 14b) is installed in each of the film forming gas and the radical supply system, and the radical / gas used in the next process is not stopped during the gas / radical supply, but is exhausted from the bypass pipe 14. Like to do. Preparation is necessary for the supply of the raw material gas / radical, and it takes time until the supply starts. Therefore, during the treatment, the supply of the raw material gas / radical is always stopped without stopping, and when not in use, the exhaust gas is exhausted from the bypass pipe 14 so that the raw material gas / radical is immediately switched by simply switching the valves 21 to 24 during use. Supply can be started and throughput can be improved.
[0091]
(7) Trap sharing
In the embodiment, the trap 16 is shared by the film forming gas and the radical exhaust system. That is, as shown in FIG. 1, a raw material recovery trap 16 for recovering the raw material is installed in the exhaust pipe 7, and the bypass pipe 14 is connected to the raw material recovery trap 16, so that the trapped liquid raw material is oxygen radicals. It is possible to convert the solid into a solid and prevent the raw material from flowing into the exhaust pump (not shown) due to revaporization. As a result, the raw material recovery rate can be improved, the inflow of the raw material to the exhaust pump and the abatement apparatus (not shown) can be reduced, and the maintenance cycle of the substrate processing apparatus can be greatly extended.
[0092]
(8) Use of plasma source
In the embodiment, the plasma source used for activating the gas in the RPO process in the reforming step and the plasma source used for activating the cleaning gas in the cleaning step are shared. In the cleaning process, the film adhered in the reaction chamber 1 is removed using the cleaning gas activated by the plasma generated in the reactant activation unit 11, and the plasma generated in the reactant activation unit 11 in the reforming process. The film is reformed using the reactant activated by the above, and the plasma source for reactant activation and cleaning gas activation is shared, making it easy to manage the plasma source and reducing the cost of the semiconductor device Can be manufactured.
[0093]
(9) Processing performed in the same device
According to the embodiment, (HfO₂Since film formation → RPO processing) × n cycles from the formation of the metal oxide film to the electrode formation are performed in the same apparatus, the temperature raising time of the substrate can be saved as compared with the case where the electrode formation is performed by a different apparatus. Further, the electrode can be formed while the surface of the film is in a clean state. Further, since the metal oxide film is densified by thermal annealing performed at the time of electrode formation, the electrode can be formed without performing an annealing process as a separate process from the metal oxide film electrode forming process after the metal oxide film is formed. Is less susceptible to contamination. This will be specifically described below.
[0094]
FIG. 6 shows HfO obtained by the seven-cycle process (the present invention) of the embodiment.₂HfO obtained by membrane and one cycle treatment (conventional method)₂The electrical insulation characteristics before and after the RTA treatment are shown for the film. HfO on the horizontal axis₂The electric field (arbitrary unit) applied to the film (10 nm), and the vertical axis represents the leakage current (arbitrary unit). Note that the RTA treatment here refers to atmospheric pressure (O₂In the atmosphere) at high speed. In the figure, conventional HfO₂And HfO obtained by one cycle treatment₂Representing a membrane, the present invention HfO₂And HfO obtained by 7-cycle treatment₂Represents a membrane. “Without RTA” means that before RTA processing, and “With RTA” means that after RTA processing. According to FIG. 6, the one obtained by one-cycle processing (conventional HfO (without RTA)) has a large amount of CH and OH mixed, and the insulation characteristics change significantly before and after RTA. The insulating film obtained by the 7-cycle treatment (the present invention HfO (without RTA)) has a small amount of CH and OH, so that the insulation characteristics at the initial stage (state where no electrical stress is applied for a long time) are almost the same before and after the RTA. I understand that there is no. Thus, by performing the cycle process of the present embodiment, it is possible to reduce the RTA process required for improving the electrical insulation of the thin film and ensuring its stability.
[0095]
By reducing the RTA processing, the configuration of the cluster apparatus can be simplified. This will be described with reference to FIG. 7 showing the cluster device configuration.
[0096]
The cluster apparatus includes a substrate transfer chamber 40 provided with a substrate transfer robot 41, a load lock chamber 42 for loading / unloading substrates to / from the apparatus, a first reaction chamber 43 for surface-treating substrates (RCA cleaning, etc.), and FIG. HfO as shown CVD reaction chamber₂A second reaction chamber 44 for forming a film and a third reaction chamber 45 for forming an electrode on the thin film are provided.
[0097]
In the conventional cluster apparatus configuration (see FIG. 20), the substrate surface treatment is performed in the first reaction chamber 33, and the HfO in the second reaction chamber 34.₂A film was formed, RTA treatment was performed in the third reaction chamber 35, and electrodes were formed in the fourth reaction chamber 36. On the other hand, according to the embodiment of FIG. 7, after the substrate is carried into the load lock chamber 42 from the outside of the apparatus, substrate surface treatment such as RCA cleaning is performed in the first reaction chamber 43, and in the second reaction chamber 44. HfO₂The film formation and the modification process are repeated (HfO₂Film formation → Modification process → HfO₂Film formation → reforming treatment →...), HfO with a predetermined film thickness₂Film formation is performed, and electrodes (poly-Si thin film formation and thermal annealing treatment) are formed in the third reaction chamber 45. Then, the substrate on which the electrode is formed is carried out of the apparatus from the load lock chamber 42.
[0098]
FIG. 8 shows the HfO of the substrate obtained by the cluster device configuration of the conventional example and the embodiment described above.₂The figure which compared the electrical property of the film | membrane is shown. Capacitance (arbitrary unit) on the horizontal axis and HfO on the vertical axis₂The leakage current (arbitrary unit) when the film thickness is about 5 nm, about 10 nm, and about 15 nm is shown. From the figure, HfO obtained by the conventional tarask apparatus (one cycle process) shown in FIG.₂From the film characteristics (outlined points in the figure), the cluster device (HfO) of the embodiment shown in FIG.₂The film shows that the characteristics (black points in the figure) obtained by 7 cycle treatment) are superior. This result shows that the RTA process is not required, and such a cluster configuration that does not require the RTA process can be achieved in the second reaction chamber 44 of FIG.₂This is probably because the CH and OH removal treatment from the film is sufficiently performed by the process according to the present embodiment.
[0099]
Therefore, in this embodiment, the reaction chamber for RTA can be omitted from the cluster apparatus, and the configuration can be simplified. In addition, since RTA processing for removing CH and OH is not performed, HfO₂The surface state of the film does not lose flatness, and HfO₂The film is not partially crystallized and the insulation and its stability are not lowered.
[0100]
In the embodiment, HfO₂After the film is formed in the second reaction chamber 44, the electrode is formed in the third reaction chamber 45 in the same cluster apparatus without performing the RTA process. Thus, HfO₂When forming the film (second reaction chamber) and then performing the electrode formation (third reaction chamber) in the same apparatus,
[0101]
(1) After the substrate is taken out from one apparatus and loaded into another apparatus, it is possible to save the reheating time for heating the substrate again.
(2) By thermal annealing at 700 ° C. or higher performed at the time of electrode formation, HfO₂Since the film is densified, the film surface is hardly contaminated.
(3) HfO₂Electrodes can be formed with the film surface kept clean.
There is such a merit.
HfO₂After forming the film (second reaction chamber), the substrate may be taken out of the apparatus and the electrode may be formed by another apparatus. However, when forming the electrode with another device like this,
[0102]
{Circle around (1)} When the substrate is taken out of the apparatus, a heating time for heating the substrate again is required, and a wasteful processing time is generated.
(2) HfO formed at low temperature₂The surface of the film is easily contaminated by the atmosphere outside the apparatus, and is likely to change over time (causes deterioration of the electrical characteristics of the device).
There are disadvantages.
[0103]
In order to eliminate this disadvantage, RTA treatment may be performed before electrode formation. Even in the case of the cluster device shown in FIG.₂After the formation of the film (second reaction chamber 44), for example, if the RTA treatment is performed in the third reaction chamber 45, there is no problem even if the subsequent electrode formation is performed by another apparatus. In general, the higher the temperature, the smaller the interatomic gap becomes.₂O or organic matter) is HfO₂It becomes difficult to diffuse into the film. Therefore, HfO₂This is because the film is annealed at a high temperature by the RTA process and densified, so that it is difficult to be contaminated in the atmosphere outside the apparatus or to change with time.
[0104]
(10) Modification
In the above-described embodiment, the source gas supplied to the substrate in the film forming process and the oxygen radical as a reactant supplied to the substrate in the reforming process are reacted from the same supply port by sharing the shower head. Although the interior is supplied to the room, the internal space of the shower head may be divided into a film formation and a reaction product, and the source gas and the reaction product may be supplied from separate supply ports. In this case, when supplying the source gas to the substrate from the source gas supply port in the film forming process, the non-reactive gas is supplied to the reactant supply port, and in the reforming process, the substrate is supplied from the reactant supply port. When a reactant is supplied to the non-reactive gas, it is preferable to supply a non-reactive gas to the supply port for the source gas. As described above, when the raw material gas and the reactant are supplied from separate supply ports, and a non-reactive gas such as an inert gas is supplied from a supply port that does not participate in each step, the inside of the supply port is supplied. Cumulative film formation can be sufficiently suppressed. Hereinafter, this will be described in detail with reference to FIG. The configuration shown in FIG. 9 is the same as the configuration shown in FIG. 1 except that the partition plate 15 is provided on the shower head 6.
[0105]
When the raw material adsorbed inside the shower head 6 reacts with oxygen radicals as reactants, a cumulative film is also formed inside the shower head 6. In order to suppress the formation of this accumulated film, the shower head 6 is partitioned into two (6a, 6b) by the partition plate 15. By partitioning the shower head 6 to which the source gas and oxygen radicals are supplied, the reaction between the source material and oxygen radicals can be effectively prevented.
[0106]
In addition to partitioning the shower head 6, when the deposition gas is further flowed to the substrate 4, an inert gas is allowed to flow from the radical supply side (reactant activation unit 11) to the activated gas shower head portion 6 b to generate oxygen radicals. Is preferably flowed to the substrate 4 from the source supply side (deposition source supply unit 9, inert gas supply unit 10) to the deposition shower head 6a. In this way, if an inert gas is allowed to flow through the shower head portions 6b and 6a on the side that is not used in the film forming process and the reforming process, it is possible to more effectively suppress the formation of the accumulated film inside the shower head 6. it can.
[0107]
The shower head 6 applied to FIG. 9 can be configured in various shapes. FIG. 10 shows various shapes of such a shower head 6. The shower heads having various shapes shown in FIGS. 10A to 10E have the same configuration in the following points. The shower head 6 includes a shower plate 19 having a large number of holes 8, a back plate 17 and a peripheral wall 26, a gas space 27 formed therein, and a gas space 27 that divides the gas space 27 into two shower head portions 6a and 6b. The partition plate 15 is divided. The raw material supply pipe 5 and the radical supply pipe 13 are connected to the two shower head portions 6a and 6b from the back plate 17 side of the shower head 6 thus configured, respectively.
[0108]
In FIG. 10A, the gas space 27 has a disk shape, the partition plate 15 is provided in the diameter direction of the disk-like gas space 27, and the shower head portions 6a and 6b are provided on the left and right. In FIG. 10B, the gas space has a disk shape, but the partition plate 15 is provided concentrically with the disk-like gas space, and the shower head portions 6a and 6b are provided in a coaxial double tube. ing.
[0109]
In FIGS. 10A and 10B described above, the basic shape of the shower head 6 is a point-symmetrical circle. However, in this embodiment, since the substrate is rotated, it is not a point-symmetrical circle but a line-symmetrical shape. It is also possible to make a shape such as a semicircle or a rectangle. FIG. 10C to FIG. 10E show such an example.
[0110]
In FIG. 10C, the gas space has a semi-disc shape, the partition plate 15 is provided in the radial direction of the semi-disc-shaped gas space, and the shower head portions 6a and 6b are provided on the left and right. In FIG.10 (d), the gas space is carrying out the rectangular disk shape, the partition plate 15 is provided in the center part, and the shower head parts 6a and 6b are provided in right and left. FIG. 10 (e) has a quadrangular disk shape, the partition plate 15 is provided at the center, and the shower head portions 6a and 6b are provided on the left and right. Thus, the shower head 6 can be configured in various shapes.
[0111]
In the above-described embodiment, particularly in the configuration including the following (1) to (3), HfO is formed on the substrate.₂The case where a film is formed has been described.
(1) A film forming gas used in the film forming process and a radical as a reactant used in the reforming process are supplied from the same supply port (shower head) so that they are mixed. In a modification, it supplies with a different supply port (separated shower head), and prevents both from mixing.
(2) While supplying oxygen radicals as a film forming gas or reactant, the oxygen radical or film forming gas as a reactant used in the next step is exhausted from the bypass pipe, and the next step is immediately performed by simply switching the valve. The supply of oxygen radicals or film forming gas used in step 1 can be started.
(3) Simplify maintenance by using a common trap for the film forming process and the reforming process.
However, according to the present invention, the above three components are HfO₂It is not limited to film formation. For example, Ta₂O_FiveThe present invention can also be applied to film formation of other types of films such as a film.
[0112]
【Example】
FIG. 11 shows a film formation sequence of a new MOCVD method using periodic remote plasma oxidation (RPO) in this embodiment (a procedure of a cycle method in which film formation by MOCVD and RPO are repeated a plurality of times). Here, processing was performed using the substrate processing apparatus of FIG.
[0113]
When a silicon wafer as a substrate is placed on the susceptor in the reaction chamber and the temperature of the silicon wafer is stabilized,
(1) Gaseous Hf- (MMP) vaporized by a vaporizer_FourRaw material (MO-Precursor) or dilution N₂At the same time, it is introduced into the reaction chamber for ΔMt seconds.
(2) Thereafter, gaseous Hf- (MMP)_FourThe introduction of raw materials was stopped and the reaction chamber was diluted N₂Is purged for ΔIt seconds.
(3) After purging the reaction chamber, oxygen (Remote Plasma Oxygen) activated by the remote plasma unit is introduced into the reaction chamber for ΔRt seconds. Dilution N during this time₂Continues to be introduced.
(4) After the introduction of oxygen activated by the remote plasma is stopped, the reaction chamber is again diluted N₂Is purged for ΔIt seconds.
(5) Steps (1 cycle) from (1) to (4) are repeated (n cycles) until the film thickness reaches a desired value (thickness).
In this example, Hf- (MMP)_FourFlow rate of 0.05 g / min, dilution gas N₂The flow rate of oxygen was 0.5 SLM (standard liter per minute), and the flow rate of oxygen introduced into the remote plasma unit was 0.1 SLM. The pressure in the reaction chamber was controlled to be maintained at 100 Pa by an APC (auto pressure control) valve provided in the exhaust line. HfO₂In order to measure the deposition (deposition rate) of the film, the silicon substrate was used after removing the natural oxide film on the surface with a 1% diluted HF solution.
[0114]
FIG. 12 shows an n-MOS capacitor structure for measuring a current-voltage characteristic (IV characteristic) and a capacitance-voltage characteristic (CV characteristic), and a manufacturing process flow thereof.
[0115]
For the manufacture of the n-MOS capacitor, first, a p-type silicon wafer separated by LOCOS method was used. HfO₂Prior to film formation, the silicon surface was etched with a 1% diluted Hf solution to remove the native oxide and contaminants (Cleaning-DHF + DIW + IPa). Subsequently, NH_ThreeThe silicon surface was nitrided by rapid thermal annealing at 600 ° C. for 30 seconds in an atmosphere (Surfacen nitridation). Thereafter, the above cycle treatment (HfO₂ HfO by deposition by MOCVD via cyclic RPO)₂A film is formed and N₂In the atmosphere, annealing was performed at 650 ° C. for 15 minutes (post deposition annealing). Subsequently, a TiN film having a thickness of 80 nm is formed on the TiCl film to form a gate electrode._FourAnd NH_ThreeIs grown at 650 ° C. by CVD (chemical vapor deposition) method (Gate Electrode-CVD TiN), and an area of 1000 to 10000 μm is formed by photolithography mask fabrication and etching²The gate electrode of the MOS capacitor was formed. HfO₂The oxide equivalent film thickness (EOT) of the film is an area of 10000 μm²The CV curve measured with the electrode of No. 1 was obtained using the CVC program developed by NCSU. The IV characteristic has an area of 1000 μm.²The temperature was measured at 100 ° C. In order to examine the quality of the film, TDS (thermal desorption spectroscopy) characteristics and SIMS (Secondary Ion Mass Spectroscopy) profiles were also measured. In order to investigate the crystal structure of the film, high-resolution TEM ([HRTEM] cross-section high-resolution transmission electron microscopy) images were also observed.
[0116]
FIG. 13 shows the HfO film formed using the above cycle method.₂The substrate temperature dependence of the growth rate of the thin film is shown (black points in the figure). The vertical axis represents the growth rate, and the horizontal axis represents the temperature. Each step time of ΔMt, ΔIt, and ΔRt in the cycle method was 30 seconds. HfCl conducted by Cho et al. As a comparative example_FourAnd H₂HfO by ALD with O₂Also shown is the data (open dots in the figure). The film formation rate is expressed in units of nm / min for comparison with data such as Cho.
[0117]
HfCl_FourAnd H₂In the case of ALD using O, the deposition rate decreased from 1.2 nm / min to 0.36 nm / min as the substrate temperature (growth temperature) was changed (increased) from 180 ° C. to 400 ° C. This is because in the case of ALD, the amount of raw material adsorbed on the wafer surface decreases as the substrate temperature is increased. However, in the case of the new cycle method invented by the present inventors, the film formation rate increases from 0.3 nm / min (0.6 nm / cycle) to 1 as the substrate temperature (growth temperature) is increased from 300 ° C. to 490 ° C. Increased to 5 nm / min (3 nm / cycle). This is because the self-decomposition of the raw material is promoted by increasing the film forming temperature. In addition, since it takes time until the flow rate is stabilized in the used liquid mass flow controller, it has been found that only Δs of 30 seconds ΔMt actually contributes to the film formation. Therefore, the film formation rate is lower than that of ALD at low temperatures. If the time during which the raw material actually contributes to film formation can be increased, the film formation rate can be made larger than that of ALD even at a low temperature.
[0118]
A 30 nm thick HfO film deposited at different cycle numbers using the cycle method₂The thin film was evaluated by TDS. FIGS. 14A, 14B, and 14C show HfO, respectively.₂Thin film hydrogen, H₂TDS spectra of O and CO are shown. The four spectra in (a), (b), and (c) are HfO films formed by a cycle method at 425 ° C. in 1, 10, 20, and 40 cycles, respectively.₂It relates to a thin film. The step times of 1, 10, 20, and 40 cycle processing are 1200, 120, 60, and 30 seconds, respectively. In other words, films formed in 1, 10, 20, and 40 cycles have been subjected to RPO treatment every 30, 3, 1.5, and 0.75 nm, respectively.
[0119]
From FIG. 14 (a), it can be seen that the desorption of hydrogen from the 10, 20, and 40 cycle samples is dramatically reduced compared to the one cycle sample. Further, from FIGS. 14B and 14C, CO desorption hardly changes depending on the number of cycles, whereas H₂It can be seen that the desorption of O gradually decreases as the number of cycles increases. We compared the TDS spectra of samples that had previously been RPO-treated and those that were not so that HfO₂The RPO after thin film deposition is hydrogen and H₂It has been found that it is effective in reducing O contamination. From these facts, periodic RPO is hydrogen and H₂It can be said that it is effective in reducing the mixing of O.
[0120]
Hf- (MMP)_FourBy HfO₂In order to investigate the mechanism of impurity contamination in the thin film, Hf- (MMP)_FourThe self-decomposition reaction of was examined as follows.
[0121]
First, Hf- (MMP)_FourThe solution was left in Ar gas at 300 ° C. for 5 hours, then diluted with toluene, and analyzed by GC-MS (Gas Chromatography-Mass Spectroscopy). The detected by-product is Hf- (MMP)_Four, (CH_Three)₂C = CHOCO_Three(Olefin), (CH_Three)₂CHCHO (isobutylaldehyde), (CH_Three)₂CHCH₂OH (isobutanol), CH_ThreeOH (methanol), CH_ThreeC (= 0) CH_Three(Acetone). Olefin is produced by separation of HfO-C bond and separation of hydrogen (H) bound to carbon (C) at β-position of MMP. Isobutyldehyde, isobutanol, methanol, and acetone are thought to be formed by the decomposition of H-MMP and olefin. Hf- (MMP)_FourThe following equation is considered to be appropriate as a reaction model.
Hf (MMP)_Four→ Hf (OH) + 4olefin (4)
Or
Hf (MMP)_Four→ HfO₂+ 2H (MMP) + 2olefin (5)
Here, from the equation (4), Hf- (MMP)_FourHfO deposited by MOCVD using₂It is expected that hydrogen will easily enter. This is because HfO deposited by MOCVD measured previously.₂This is confirmed from the TDS spectrum of the film, which is consistent with the fact. However, as shown in FIG. 14, in the film subjected to the RPO process for every film thickness of 3 nm or less, almost no hydrogen is mixed. Therefore, the RPO process completely oxidizes Hf (OH) as shown in the following formula. It seems to be doing.
Hf (OH) + O * → HfO₂+ 1 / 2H₂                        (6)
Or
2Hf (OH) + 3O * → 2HfO₂+ H₂O (7)
O * is an oxygen radical.
Here, even if the reaction of the formula (7) occurs on the surface of the deposited film, the generated H is generated from the surface of the thin film.₂Since O is exhausted, it is considered that it is difficult to be taken into the film. However, since oxygen radicals (O *) also react with Hf (OH) present in the film, HfO₂In the thin film, H₂O is taken in. As a result, as shown in FIG. 14, the HfO film formed using the cycle method was used.₂Even a thin film has H in the film.₂O exists and its H₂Contamination due to the mixing of O decreases as the film thickness of one cycle subjected to the RPO process decreases.
[0122]
FIG. 15 shows HfO formed at 425 ° C. by a conventional MOCVD method.₂Sample (MOCVD at 425 ° C.) and HfO deposited at 300 ° C. and 425 ° C. by the cycle method₂The SIMS profile of carbon ((a) carbon) and hydrogen ((b) hydrogen) of the sample (Cyclic Method at 300 ° C., 425 ° C.) is shown. The film thickness of these samples is about 5 nm. Samples at 300 ° C. and 425 ° C. were deposited in 100 and 10 cycles, respectively, with a step time of 30 seconds.
[0123]
From FIG. 15, the amounts of carbon (C) mixed in the MOCVD method, the cycle method of 300 ° C., and the cycle method of 425 ° C. are 1.4, 0.54, 0.28 at. %. In addition, the mixing amounts of hydrogen (H) in the sample of MOCVD, 300 ° C. of the cycle method, and 425 ° C. of the cycle method are 2.6, O.D. 8, 0.5 at. %. The result that the mixing of C and H is less in the cycle method than in the MOCVD method indicates that the cycle method is effective in reducing the mixing of C and H. According to a report by Kukli et al., The amount of hydrogen mixed in films formed by ALD at 300 ° C. and 400 ° C. was 1.5 and 0.5 at. %Met. This indicates that the amount of hydrogen mixed in the film formed by the cycle method is not inferior to that of ALD. The reason why the amount of carbon contamination is reduced is as follows. As shown in the above formulas (4) and (5), Hf- (MMP)_FourAfter introducing, Olefin and H-MMP are generated. Various types of alcohols are also produced by the degradation of Olefin and H-MMP. Most of these by-products are exhausted from the surface of the thin film, but some is adsorbed on the thin film surface. Here, by the RPO step, these adsorbates are converted into CO, CO₂, H₂It is decomposed into O and the like and exhausted from the surface of the thin film by the next purge step. Chen et al. Introduced ZrO in “pulse mode”, such as introducing MO raw material and oxygen with 15 seconds of exhaust.₂A thin film was formed and the amount of mixed C was 0.1 at. %, But this is also considered to be caused by the decomposition of organic substances in the oxygen introduction step and the exhaust in the subsequent exhaust step. However, the present invention has an advantage over the method of Chen et al. In that remote plasma oxygen that is more active than oxygen is used and the decomposition efficiency of alcohol or the like is high. Further, it can be seen that the amount of impurities in the cycle method is decreased by increasing the film formation temperature. This is because the amount of adsorption of by-products decreases as the film formation temperature rises. For these reasons, it can be concluded that in the cycle method, it is better to shorten the material introduction time ΔMt and to increase the remote plasma introduction time ΔRt. Further, it can be said that the film formation temperature should be higher as long as the raw material is not decomposed in the gas phase.
[0124]
HfO₂Many metal oxides such as a film tend to form a crystallized structure in the film when the temperature is increased as shown in FIG. In the conventional MOCVD method, many crystallized portions were already included in the film by deposition at 300 ° C. or higher. However, in the present invention, the crystallization temperature is shifted to the high temperature side as shown in FIG.₂It has been found that a film is obtained. The TEM photograph shown in FIG. 17 shows an example, and it has been found that the amorphous structure is maintained even at a temperature at which crystallization is performed conventionally.
[0125]
FIGS. 17 (a) and (b) are HRTEM images of samples deposited at 425 ° C. for 1 and 4 cycles with step times of 120 seconds and 30 seconds, respectively. HfO₂Before thin film formation, NH_ThreeAn interface layer of 0.8 nm is formed by annealing. In the TEM image, the portion that appears black is HfO containing HfO₂It is a film (heavy atoms appear black). Generally, if there is no regularity in the part, it is said to be amorphous, and if there is regularity, it is said to be crystallized. However, from the viewpoint of the whole film (in a large sense), it can be said that even if it is partially crystallized, it is amorphous.
[0126]
17A and 17B, since the interface layers of 1 and 4 cycles are 1.7 nm and 1.6 nm, the RPO processing step time has an influence on the formation of the interface layer. It is not considered. However, in another experiment, the substrate and HfO₂It has been found that the thickness of the undesired interface layer formed between the films can be made thinner than conventional MOCVD deposition. From FIG. 17, HfO deposited in one cycle.₂While the thin film is more crystallized, the HfO film formed in 4 cycles₂It can be seen that the thin film has an amorphous structure. Kukli et al. Described ZrO deposited by ALD.₂The film was reported to have an amorphous structure at 210 ° C but crystallized at 300 ° C. Aarik et al. Described HfO deposited at 300 ° C. by ALD.₂It is reported that the membrane had been used. From these facts, the cycle method of the present invention can be said to be a method suitable for maintaining the film in an amorphous structure. When the film thickness uniformity was examined, it was confirmed that the film formation in 4 cycles was better than the film formation in 1 cycle.
[0127]
FIG. 18 shows the HfO film formed at 425 ° C. by the MOCVD method and the cycle method.₂The relationship between the EOT of the capacitor and the leakage current measured at -1V is shown. The vertical axis represents leakage current (Jg @ -1V), and the horizontal axis represents EOT. HfO₂Before thin film formation, NH_ThreeAn interface layer of 0.8 nm is formed by annealing. HfO deposited by cycle method₂The film thicknesses of the thin films are 2.3, 3.1, 3.8, and 4.6 nm, respectively. HfO deposited with different film thickness by MOCVD method₂Of the films, the CV characteristic was obtained only when the film thickness was 5 nm or more. White dots and black dots indicate the results when the films are formed by the MOCVD method and the cycle method, respectively.
[0128]
From FIG. 18, HfO formed by the cycle method.₂It can be seen that the leakage current of the thin film is 1/100 or less of the film formed by the MOCVD method. The reason why the leakage current is reduced by the cycle method is HfO₂The reduction of impurities in the film and the film structure are in an amorphous state.
[0129]
As described above, the present inventors have found an advantage of a new MOCVD method using periodic RPO. That is, in the case of the cycle method, it has been found that the amount of impurities contained in the film can be reduced by raising the film formation temperature and shortening the introduction time of the raw material. It has also been found that the film formed by the cycle method has an amorphous structure, and the cycle method is preferable for maintaining the amorphous structure. As a result, HfO₂The leakage current of the film decreased. In addition, the cycle method can improve the film thickness uniformity over the conventional MOCVD film formation, and further, the film formation base and HfO₂It has also been found that the thickness of the interface layer formed between the films can be reduced.
[0130]
【The invention's effect】
According to the present invention, the metal oxide film is formed without using a gas containing oxygen atoms during the film forming step. Therefore, the specific element in the metal oxide film is effectively removed during the reforming step. Can be easily modified.
[0131]
In addition, since the film forming gas and the reactant are supplied from the same supply port, the foreign matter adhering to the inside of the supply port is covered with a thin film, and the foreign matter can be prevented from falling onto the substrate. Removal of by-products and cleaning gas adsorbed inside the supply port can be performed.
[0132]
In particular, when the formation of the film containing Hf and the modification of the film using the reactant are continuously performed, the specific element in the film containing Hf formed in the film forming step is quickly removed. Can be modified. In this case, when the film thickness of the Hf-containing film formed at one time is 0.5 to 30 mm (1/6 atomic layer to 10 atomic layer), the modification treatment can be performed in a state where crystallization is difficult, The film can be modified by effectively removing impurities.
[0133]
In addition, after forming the thin film, the throughput can be improved by forming the electrode without performing an annealing process as a separate process from the electrode forming process and performing the process from forming the thin film to forming the electrode in the same apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a reaction chamber in an embodiment.
FIG. 2 shows the degree of Hf—O—Hf bond binding to HfO₂When forming a film | membrane, it is the figure compared with the case where it forms without oxygen, and the case where it forms with oxygen.
FIG. 3 HfO₂The amount of impurities contained in the film (—OH, C—H, C—O) is expressed as HfO.₂When forming a film | membrane, it is the figure compared with the case where it forms without oxygen, and the case where it forms with oxygen.
FIG. 4 shows the number of cycles and HfO.₂It is a graph which shows the relationship of the C and H impurity total amount in a film | membrane.
FIG. 5 shows HfO on the substrate.₂It is sectional drawing which shows the state in which the film | membrane was formed.
FIG. 6 is a graph showing the relationship between the number of cycles and insulation characteristics.
FIG. 7 is a conceptual diagram showing a cluster device configuration in the embodiment.
FIG. 8 shows HfO by the cluster device configuration in the conventional example and the embodiment.₂It is a graph which shows the electrical property of a film | membrane.
FIG. 9 is a schematic explanatory diagram of a reaction chamber in a modified example.
FIG. 10 is an explanatory diagram showing various examples of showerhead shapes according to the embodiment.
FIG. 11 is a diagram illustrating a film forming sequence by MOCVD and RPO cycle processing in an example.
12 is a diagram illustrating an n-MOS capacitor structure used for measurement of CV characteristics and IV characteristics in an example and a manufacturing procedure thereof. FIG.
FIG. 13 shows HfO formed by cycle processing.₂It is a figure which shows the substrate temperature dependence of the growth rate of a film | membrane.
FIG. 14 shows HfO formed by changing the number of cycles.₂Hydrogen in the film, H₂It is a figure which shows the TDS spectrum of O and CO.
FIG. 15 is a diagram showing SIMS profiles of (a) carbon and (b) hydrogen of a sample formed by a conventional MOCVD method and a cycle treatment in an example.
FIG. 16 is a comparison diagram of the present invention and the prior art showing temperature characteristics of the degree of crystallization.
FIG. 17 shows HRTEM images of samples formed in 1 cycle and 4 cycles.
FIG. 18 shows HfO formed by a conventional MOCVD method and a cycle process in an example.₂It is a figure which shows the relationship between EOT of a capacitor, and leakage current.
FIG. 19 is a conceptual explanatory diagram of a CVD reaction chamber in a conventional example.
FIG. 20 is a conceptual diagram showing a cluster device configuration in a conventional example.
[Explanation of symbols]
1 reaction chamber
4 Substrate
5 Raw material supply pipe
6 Shower head
7 Exhaust pipe
9 Deposition raw material supply unit
11 Reactant activation unit
14 Bypass pipe
15 Partition plate
16 traps
25 Control device

Claims (10)

A source gas obtained by vaporizing a source material in a liquid phase at room temperature and normal pressure is supplied to the substrate, and a gas containing oxygen atoms is not supplied to the substrate other than the source gas, or the source gas is supplied to the substrate. A film forming step of forming an oxide film on the substrate by supplying a gas containing a small amount of the oxygen atoms that is substantially the same as when forming a film without supplying a gas containing oxygen atoms,
A reforming step for reforming the oxide film formed in the film-forming step using a reactant different from the source gas;
In the manufacturing method of a semiconductor device having a step of repeating a plurality of times continuously,
The source gas used in the film formation step includes a source gas obtained by vaporizing a source material containing oxygen atoms and hafnium atoms, and the oxide film formed in the film formation step is an oxide containing hafnium having a thickness of 0.5 to 30%. A method of manufacturing a semiconductor device, wherein the method is a film. A film formation step of forming a hafnium-containing oxide film having a thickness of 0.5 to 30 mm on the substrate by supplying a source gas obtained by vaporizing a material including oxygen atoms and hafnium atoms to the substrate in a non-oxygen atmosphere When,
A reforming step of reforming the hafnium-containing oxide film formed in the film-forming step using a reactant different from the source gas;
Is continuously performed at least once. A method for manufacturing a semiconductor device. A film forming step of forming an oxide film containing hafnium having a film thickness of 0.5 to 30 mm on a substrate without using an oxidizing gas, using a source gas obtained by vaporizing a material containing oxygen atoms and hafnium atoms;
A reforming step of reforming the hafnium-containing oxide film formed in the film-forming step using a reactant different from the source gas;
Is continuously performed at least once. A method for manufacturing a semiconductor device. A film forming step of forming an oxide film on a substrate without using a gas containing oxygen atoms in addition to the source gas, using a source gas obtained by vaporizing a source material in a liquid phase at room temperature and normal pressure;
A reforming step for reforming the oxide film formed in the film-forming step using a reactant different from the source gas;
In the manufacturing method of the semiconductor device having
The source gas used in the film formation step includes a source gas obtained by vaporizing a source material containing oxygen atoms and hafnium atoms, and the oxide film formed in the film formation step is an oxide containing hafnium having a thickness of 0.5 to 30%. A method of manufacturing a semiconductor device, wherein the method is a film. A film forming step of forming an oxide film on a substrate without using a gas containing oxygen atoms in addition to the source gas, using a source gas obtained by vaporizing a source material in a liquid phase at room temperature and normal pressure;
A reforming step for reforming the oxide film formed in the film-forming step using a reactant different from the source gas;
In the manufacturing method of a semiconductor device having a step of repeating a plurality of times continuously
The source gas used in the film forming step includes a source gas obtained by vaporizing a source material containing oxygen atoms and hafnium atoms, and the oxide film formed in the film forming step is an oxide film containing hafnium,
Method of manufacturing a semi-conductor device, characterized in that the raw material containing the oxygen atom and a hafnium atom, a _{Hf [OC (CH 3) 2} CH 2 OCH 3] 4. A film forming step of forming an oxide film on a substrate without using a gas containing oxygen atoms in addition to the source gas, using a source gas obtained by vaporizing a source material in a liquid phase at room temperature and normal pressure;
A reforming step for reforming the oxide film formed in the film-forming step using a reactant different from the source gas ;
In the manufacturing method of a semiconductor device having a step of repeating a plurality of times continuously
The source gas used in the film forming step includes a source gas obtained by vaporizing a source material containing oxygen atoms and hafnium atoms, and the oxide film formed in the film forming step is an oxide film containing hafnium,
Method of manufacturing a semi-conductor device you wherein a thickness of the oxide film containing the hafnium to form a single said deposition step is 0.5A～30A. The reaction process according to claim 6 Symbol mounting the semiconductor device characterized by comprising an oxygen atom. 7. The method of manufacturing a semiconductor device according to claim 6, wherein the reactant contains a gas obtained by activating a gas containing oxygen atoms. The method of manufacturing a semiconductor device according to claim 6, wherein the film forming step and the modifying step are performed in the same reaction chamber. A reaction chamber for processing the substrate;
A supply pipe for supplying a raw material gas obtained by vaporizing a raw material containing oxygen atoms and hafnium atoms into the reaction chamber; and a supply pipe for supplying a reactant different from the raw material gas into the reaction chamber;
The source gas is supplied into the reaction chamber in a non-oxygen atmosphere to form an oxide film containing hafnium having a thickness of 0.5 to 30 mm on the substrate, and the reactant is supplied onto the substrate by supplying the reactant into the reaction chamber. A control device that performs modification of the hafnium-containing oxide film formed on the substrate and performs control so that the oxide film is continuously performed at least once.
A substrate processing apparatus comprising:

Images