JP2001035842A - Cvd device and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain dispersion of characteristics in products by improving film formation characteristics while ensuring productivity, by keeping a reaction chamber at an atmospheric pressure in a standby state of a device when it is not operated during deposition of oxide of a high melting point metal under decompression. SOLUTION: Introduction I of oxygen O2 is carried out in a reaction chamber of a CVD device before deposition II and thereafter deposition II is carried out. In a standby state III, oxygen O2 or nitrogen N2, etc., is introduced and a reaction chamber is maintained at an atmospheric pressure. Next, film formation IV is carried out properly. As for the most preferable form, a substrate is carried in a reaction chamber and evacuated, individual introduction of oxygen and temperature stabilization are carried out, a deposition process is executed by introducing reaction gas, reaction gas is discharged (evacuation) thereafter, and an atmospheric pressure is held by oxygen in a standby state of a device while carrying out a substrate from a reaction chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CVD apparatus and a method for manufacturing a semiconductor device. In particular, the present invention provides a CVD apparatus for depositing a high-melting-point metal oxide and a method for manufacturing a semiconductor device having a step of depositing a high-melting-point metal oxide. It is an object of the present invention to provide a technique that can improve characteristics and suppress variations in characteristics of products.

[0002]

2. Description of the Related Art Conventionally, for example, a dynamic random access memory (DRAM) has been known.
In an LSI or the like including a sess memory, a silicon nitride film (Si ₃ N ₄ or the like) or a silicon oxide film (SiO ₂
Etc.) are used. 2. Description of the Related Art In recent years, as semiconductor devices become more highly integrated, the area that a capacitor can occupy in a semiconductor device is also decreasing. On the other hand, in order to maintain reliability such as insulation resistance and soft error resistance, the capacitance value is required to be rather increased. In order to secure a capacitance value while limiting the area occupied by the capacitor, it is effective to use a material having higher dielectric properties as the dielectric film forming the capacitor. As such a high dielectric film, a technique using an oxide of a high melting point metal having a high dielectric constant has been developed. Typically, it is an oxide of tantalum, specifically, Ta ₂ O ₅ (tantalum pentaoxide: Tantalum Penta Oxide).
With respect to (1), it has been developed to use the thin film as a dielectric film.

The dielectric constant of each material is as follows. _{SiO 2; ~3.9~ Si 3 N 4} ; ~7~ Ta 2 O 5; ~25~ Ta 2 O 5 is found to be particularly high dielectric constant.

[0004] Recently, technology for employing a Ta ₂ O ₅ thin film as a gate insulating film of a MOS transistor has been developed, and in the future, the Ta ₂ O ₅ thin film will attract attention as an increasingly useful material. Become.

Techniques for forming a Ta ₂ O ₅ thin film include a sputtering method and a CVD (Chemical Vapor Deposition; Chemical).
The Vapor Deposition method, the sol-gel method, and the like have been studied. At present, reduced pressure CVD by thermal reaction
Many processes have been adopted, and as the manufacturing apparatus, a batch type apparatus and a single wafer type apparatus have been developed.

[0006] Batch-type apparatuses are widely used because they can process a plurality of substrates (substrates and the like) at a time and thus have excellent productivity. The batch-type apparatus needs to have a wide area where the temperature in the reaction chamber, which greatly affects the formation of a thin film, is uniform and stable because of the property of simultaneously processing a plurality of objects (substrates and the like). For this reason, in a batch type CVD apparatus, a radiant heating method using a resistance heater is widely used as a method for heating a substrate or the like, which is an object to be processed. A type of device will be used. In this specification, the “hot wall type” means that a processing chamber such as a reaction chamber is heated from outside to a desired temperature by heating means such as a resistance heater so that the temperature in the processing chamber is as large as possible. , A type that is uniform and stable.

As a technique for forming a Ta ₂ O ₅ thin film, a vertical batch type reduced pressure CVD apparatus has been developed. Recent C
2. Description of the Related Art In a VD apparatus, a structure in which a load lock chamber is provided in a transfer system of a processing target (substrate or the like) is often used. This is a structure for preventing entry of moisture, organic matter, and the like due to entrainment of air into the reaction chamber during transfer of a processing target (substrate or the like). In this type of CVD apparatus, conventionally, in a device standby state between operations, the reaction chamber is maintained under reduced pressure.

However, in a low pressure CVD apparatus for forming a Ta ₂ O ₅ thin film, there is a problem that the film formation characteristics after the standby are changed by holding the reaction chamber under reduced pressure during the standby. Specifically, there is a problem in that the film forming speed of the Ta ₂ O ₅ thin film fluctuates in the operation after the apparatus is kept on standby. This is the deposition of a Ta ₂ O ₅ thin film (De
po) It is considered that the rate fluctuates. In addition, there is a phenomenon that the uniformity of the in-plane film thickness is deteriorated in the substrate or the like to be processed.

[0009] Both of these phenomena act in a direction to increase the thickness variation of the Ta ₂ O ₅ thin film, thus resulting in a tendency allowed to rise to characteristic variations of products using Ta ₂ O ₅ thin film. For example, in the case of a capacitor using a Ta ₂ O ₅ thin film as a dielectric film, a change in characteristics of the capacitor itself is induced.

In the prior art, as a countermeasure against the above problem,
When the working time of the apparatus is free, work for stabilizing the film forming characteristics is particularly performed. However, usually, the batch type decompression CV
The film forming operation in the D apparatus takes time, and a large amount of time is required for the operation for stabilizing the film forming characteristics. That is, since the film formation operation in the batch type low-pressure CVD apparatus usually takes about 2 to 4 hours, the above measures degrade the productivity. Further, the allowable time for leaving the apparatus is unclear, and operation is difficult.

With reference to the accompanying drawings, the prior art will be specifically described, and the above-mentioned problems will be further described. Please refer to FIG. FIG. 6 shows an example of the structure of a general batch-type vertical low-pressure CVD apparatus. This is a batch-type reduced-pressure CVD apparatus having a vertical reaction chamber, which can be used as a semiconductor manufacturing apparatus for forming a Ta ₂ O ₅ thin film. This structure has the advantages that a plurality of substrates can be processed at the same time, and the occupied area of the apparatus is small.

The vertical low-pressure CVD apparatus 1 includes a reaction chamber 2 for forming a thin film on a substrate under reduced pressure, a gas supply system for supplying a reaction gas or the like to the reaction chamber 2, and a gas in the reaction chamber 2. And a transport system 6 for transporting the substrate 5. The substrate 5 on which a desired Ta ₂ O ₅ thin film is to be formed is inserted into the reaction chamber 2 by the transfer boat 7. The heating of the substrate 5 in the reaction chamber 2 is performed by the radiant heat of the resistance heating hitter 8 surrounding the periphery of the reaction chamber 2. Further, in this structural example, a load lock chamber 9 is provided in a stage preceding the reaction chamber 2. In particular, since the formation of the Ta ₂ O ₅ thin film is a surface reaction, in order to form the thin film with good controllability, it is particularly preferable to provide a load lock chamber in addition to the batch type.

As for the film forming characteristics of the Ta ₂ O ₅ CVD apparatus 1 having the conventional structure, stable film forming reproducibility and good in-plane film thickness uniformity can be obtained as long as continuous film forming is performed. . However, if the film forming operation is temporarily stopped and the apparatus has a waiting time, there is a problem that the film forming characteristics are changed in the subsequent first film forming operation. Specifically, it is a phenomenon in which the reproducibility of film formation is deteriorated due to a decrease in deposition rate, and the uniformity in film thickness in the substrate is deteriorated. Both of these are Ta ₂ O ₅
This deteriorates the uniformity of the film quality of the thin film and deteriorates the concentration of the characteristics of the finally formed capacitor.

As an example of the prior art, FIG. 8 shows film forming characteristics when a Ta ₂ O ₅ thin film is formed by a CVD apparatus having the structure shown in FIG. This is a film formation characteristic when three continuous film formations are defined as one cycle and three cycles are repeatedly performed with an apparatus standby time of about 10 hours. FIG. 8A shows the Depo Rate (deposition rate) in each film formation, and FIG. 8B shows the film thickness uniformity in the substrate in each film formation. 1-1, 1-2, and 1-3 represent each film formation in the case where three continuous film formations are performed under the condition 1 to make one cycle, and 2-1 to 2-2 and 2-3 are: In the conditions of the next cycle, 3-1, 3-2, and 3-3 indicate each film formation performed three times under the conditions of the next cycle.

The Ta ₂ O ₅ thin film is formed by reacting pentaethoxy tantalum (Penta) as a Ta gas source.
Etoxi Tantalum; Ta (OC ₂ H ₅ )
₅ ) Using oxygen and the following conditions. Temperature: 420 ° C. Degree of vacuum: 40 Pa Ta (OC ₂ H ₅ ) ₅ flow rate: 0.1 SCCM Oxygen flow rate: 1.0 SLM

In this evaluation, a plurality of evaluation substrates are set in the transfer boat in consideration of the film forming characteristic variation depending on the substrate setting position in the transfer boat.
The oRate (deposition rate) or the average value of the film thickness uniformity in the substrate is connected by an interpolation curve, and the width indicates the maximum value and the minimum value. As can be understood from FIG. 8, the first operation after the standby of the apparatus (see the data of 1-1, 2-1 and 3-1) is De.
It can be seen that the po rate (deposition rate) is significantly reduced and the in-plane film thickness uniformity is significantly deteriorated.

[0017]

As described above, in the prior art, in the formation of a Ta ₂ O ₅ thin film, a fluctuation in the film forming speed, especially after the apparatus is kept on standby, causes a fluctuation.
There is a problem that the film forming characteristics are not stable, and the film thickness varies, which may cause a change in the characteristics of the product. In addition, the conventional countermeasures against this problem have disadvantages such as a decrease in productivity and difficulty in operation.

This problem is not limited to the formation of a Ta ₂ O ₅ thin film.
This is a common problem to be solved for the D device.

The present invention has been made in view of the above circumstances, and suppresses variations in characteristics of a product (for example, variations in characteristics of a capacitive element in a product) by improving film forming characteristics while ensuring productivity. It is an object of the present invention to provide a CVD apparatus and a method for manufacturing a semiconductor device, which can improve the concentration of product characteristics.

[0020]

Means for Solving the Problems A CVD apparatus according to the present invention
Is an oxide of a high melting point metal (eg, Ta) under reduced pressure._Two O
_Five ) To a hot wall type CVD device
The reaction chamber at atmospheric pressure during standby conditions other than when the equipment is working.
It is characterized by being maintained.

Here, the "standby state other than when the apparatus is operating" refers to a state in which the operation of the apparatus is stopped except when performing any operation on the CVD apparatus such as a film forming operation, a cleaning operation and a maintenance operation. . Such a standby state inevitably occurs except when the apparatus is fully operated. Normally, the equipment is rarely operated at full capacity due to the personnel system and factory circumstances, and it can be said that generally there is always a standby state.

The present invention has been made based on the following findings by the present inventors. In other words, as shown in FIG.
Although the oRate (deposition rate) was significantly reduced and the in-plane film thickness uniformity was remarkably deteriorated, when the continuous film formation was performed after the standby of the apparatus, the first operation and the second and subsequent operations were performed. It is considered that the difference from the above is that the apparatus waits until film formation.

Considering the standby state of a general reduced pressure Ta ₂ O ₅ CVD apparatus, Ta ₂ O ₅ CVD is a surface reaction as described above. It is desired to suppress the entry of air into the reaction chamber. Therefore, a reduced pressure CVD apparatus for forming a Ta ₂ O ₅ thin film generally includes a load lock chamber, and holds the reaction chamber under reduced pressure in a standby state of the apparatus.
Here, the above-described invention has been made based on the idea that the problem as shown in the graph of FIG. 8 is caused by maintaining the reaction chamber under reduced pressure.

That is, according to the present invention, in the operation after the apparatus is on standby, the Depo Rate is also performed for the first operation.
(Deposition rate) does not decrease, and the in-plane film thickness uniformity does not deteriorate. Although the operation of the present invention is not always clear,
In a hot-wall type CVD apparatus, a reactant gas is adsorbed on the inner surface of a reaction chamber during a film forming operation, and the adsorbed reactant is desorbed in a standby state in which a conventional CVD apparatus is kept under reduced pressure. However, the atmosphere in the furnace was not stabilized by the time kept under reduced pressure, which is considered to have caused the above-mentioned problem. In contrast, in the present invention, the reaction chamber was maintained at the atmospheric pressure during the standby state, so that It is considered that the desorption of the adsorbate was suppressed and the problem was solved. The actual operation and effect of the present invention and consideration of the mechanism will be described in detail in the following description of the first embodiment.

[0025] A CVD apparatus according to another invention is a hot wall type C which forms a refractory metal oxide under reduced pressure.
In the VD apparatus, before the film forming step, a substance detached from the deposit is supplied to the deposit adhering to the inner surface of the reaction chamber.

The present invention relates to a hot wall type CV
The deposit deposited on the inner surface of the reaction chamber by the D apparatus became unstable due to the presence of a substance desorbed from the deposit, and was desorbed when a reaction gas was introduced into the reaction chamber in the next film forming operation. Depending on the substance, a part of the reaction gas is adsorbed on the inner surface of the reaction chamber, so that the supply amount to the wafer and the like fluctuates, and the film formation work is performed based on the idea that it causes a problem of the conventional technology. The problem of the prior art is solved by supplying the substance desorbed from the sediment before the step. The actual operation and effect of the present invention and consideration of the mechanism will be described in detail in the following description of a second embodiment.

A CVD apparatus according to still another aspect of the present invention is a hot-wall type CVD apparatus for forming a high-melting-point metal oxide film under reduced pressure, wherein a gas containing oxygen is introduced into a reaction chamber before the film-forming step. Is introduced.

In the present invention, the deposits deposited on the inner surface of the reaction chamber by the hot wall type CVD apparatus are:
It becomes unstable due to the desorption of oxygen from the sediment,
The present invention solves the problems of the prior art by supplying oxygen to the deposits based on the idea that it causes the problems of the prior art. The actual operation and effect of the present invention and consideration of the mechanism will be described in detail in the following description of a second embodiment.

Still another aspect of the present invention is a CVD apparatus,
Hot-wall CVD for forming high-melting-point metal oxide under reduced pressure
In the apparatus, a gas containing oxygen is introduced into the reaction chamber before the film forming step, and the reaction chamber is maintained at the atmospheric pressure in a standby state other than the operation of the apparatus.

According to the present invention, the invention in which a gas containing oxygen is introduced into the reaction chamber before the film forming step and the invention in which the reaction chamber is maintained at the atmospheric pressure during a standby state other than the operation of the apparatus. It can be said that both effects are obtained in combination.

A method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device having a step of forming an oxide of a high melting point metal under reduced pressure using a hot wall type CVD apparatus. The reaction chamber is maintained at the atmospheric pressure during a standby state other than the operation of the apparatus.

According to the present invention, the CV according to the above invention, in which a gas containing oxygen is introduced into the reaction chamber before the step of film formation.
With the D device, a semiconductor device having stable characteristics can be obtained.

Another method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device having a step of forming a high melting point metal oxide under reduced pressure using a hot wall type CVD apparatus. Before the step of film formation by the apparatus, a substance detached from the deposit is supplied to the deposit adhering to the inner surface of the reaction chamber.

According to the present invention, before the step of film formation, the CVD apparatus according to the present invention for supplying a substance desorbed from the deposit to the deposit adhering to the inner surface of the reaction chamber. A semiconductor device having stable characteristics can be obtained.

According to still another method of manufacturing a semiconductor device according to the present invention, there is provided a method of manufacturing a semiconductor device having a step of forming an oxide of a high melting point metal under reduced pressure using a hot wall type CVD apparatus. It is characterized in that a gas containing oxygen is introduced into a reaction chamber before a film formation step by a CVD apparatus.

According to the present invention, the CV according to the above invention, in which a gas containing oxygen is introduced into the reaction chamber before the film forming step.
With the D device, a semiconductor device having stable characteristics can be obtained.

Still another method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device having a step of forming an oxide of a high melting point metal under reduced pressure using a hot wall type CVD apparatus. A gas containing oxygen is introduced into the reaction chamber before the film formation process by the CVD apparatus, and the reaction chamber is maintained at the atmospheric pressure in a standby state other than the operation of the apparatus.

According to this invention, a gas containing oxygen is introduced into the reaction chamber before the film forming step, and the reaction chamber is maintained at the atmospheric pressure during a standby state other than the operation of the apparatus. With the CVD apparatus, a semiconductor device having stable characteristics can be obtained.

Still another method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device including a step of forming a high melting point metal oxide under reduced pressure using a hot wall type CVD apparatus. Prior to the step of inserting the film-forming substrate into the reaction chamber of the CVD apparatus, a step of forming a film of an oxide of a high melting point metal is performed so as to cover the inner surface of the reaction chamber. Is exhausted, and the substrate on which the film is to be formed is inserted into the reaction chamber.

In the present invention, the step of forming a film of the oxide of a high melting point metal so as to cover the inner surface of the reaction chamber is performed by the step of loading a substrate on which a film is to be formed into a transfer boat inserted into the reaction chamber. To improve the production efficiency.

Note that Japanese Patent Application Laid-Open No. 10-50686 discloses that
As a cleaning method for CVD apparatus, O ₂ a technique for introducing a gas or the like is mentioned, this is intended to introduce the O ₂ gas or the like as the cleaning means, solve the problems of the hot wall type CVD device It does not do.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be further described below, and preferred embodiments of the present invention will be described with reference to the drawings. However, needless to say, the present invention is not limited by the following description and the illustrated embodiments.

Prior to a description of a specific embodiment, a preferred embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows that oxygen O is supplied to a reaction chamber of a CVD apparatus._Two 
Is performed prior to film formation II, and then film formation II
And in the standby state III, the oxygen O_Two Or nitrogen
Element N _Two The reaction chamber is brought into an atmospheric pressure state by introducing a gas. Suitable
This is an embodiment in which the next film formation IV is performed. This is described next
2 has the configuration of the example shown in FIG. 3 and the configuration of the example shown in FIG.
It can be said that it was a form. Example of taking this form
Embodiment 3 will be described later.

In the most preferred embodiment, the substrate is carried into the reaction chamber, vacuum is drawn, oxygen is introduced alone and the temperature is stabilized, and a film is formed by introducing a reaction gas.
Thereafter, the reaction gas is evacuated (evacuated) to carry out the substrate from the reaction chamber, and the apparatus is kept at atmospheric pressure with oxygen in the apparatus standby state.

FIG. 2 shows a film formation II in a reaction chamber of a CVD apparatus.
In a subsequent standby state III, oxygen O ₂ or nitrogen N ₂ is introduced to bring the reaction chamber into an atmospheric pressure state, and the next film formation IV is appropriately performed. Embodiment 1 will be described later as an example of such a form.

As a preferred embodiment in this case,
The substrate is carried into the reaction chamber, vacuum evacuation and temperature stabilization are performed (approximately 30 to 60 minutes), and a reaction gas is introduced, that is, preferably, a source gas for film formation and oxygen (or nitrogen) are preferably introduced. After the process is performed, the reaction gas is evacuated (evacuated) to carry out the substrate from the reaction chamber, and the atmospheric pressure is maintained by nitrogen (or oxygen or the like) in the apparatus standby state.

FIG. 3 shows that oxygen O ₂ is introduced into a reaction chamber of a CVD apparatus.
Is performed prior to film formation II, and then film formation II
Is performed. As an example of such a mode, a second embodiment will be described later.

In a preferred embodiment in this case,
The substrate is carried into the reaction chamber, vacuum is drawn, oxygen is introduced alone and the temperature is stabilized, a film is formed by introducing a reaction gas, and then the reaction gas is evacuated (evacuated). The substrate can be unloaded, and the apparatus can be kept under reduced pressure in the apparatus standby state.

Hereinafter, a specific embodiment will be described with consideration of its configuration and operation.

Embodiment 1 In this embodiment, the present invention is applied in the form shown in FIG. 2 when a Ta ₂ O ₅ thin film is formed as a dielectric of a capacitor in the manufacture of a semiconductor device. It was done.

That is, in this example, the specific CVD
The device shown in FIG. 6 described above was used as the device, and the same operation as in the above-described conventional technique was performed.
However, here, the present invention was applied, and when the apparatus was in a standby state, N ₂ was introduced to keep the reaction chamber at atmospheric pressure.

FIG. 4 shows the film forming characteristics in this case. FIG.
FIG. 8 corresponds to FIG. 8 showing the film forming characteristics of the conventional technique described above. That is, as in the above, FIG.
When a Ta ₂ O ₅ thin film is formed by a CVD apparatus having the structure shown in FIG.
During the apparatus standby time of 0 hour, three cycles of film formation were repeatedly performed. During the apparatus standby time, the present invention was applied, and the reaction chamber was maintained at atmospheric pressure. FIG. 4A shows the film deposition characteristics at this time.
Rate (deposition rate) is shown, and FIG. 4B shows the film thickness uniformity in the substrate for each film formation. 4-1 to 3, 5-1 to
3, 6-1 to 3 correspond to the aforementioned 1-1 to 2-1 respectively.
In the prior art described above, the reaction chamber was depressurized and held during standby of the apparatus. On the other hand, the reaction chamber was maintained at atmospheric pressure during standby of the apparatus. All of these were evaluated under the same conditions, such as a ₂ O ₅ thin film forming gas and forming conditions.

As shown in FIG. 4, the deposition rate is also
The uniformity of the film thickness in the substrate is also remarkably improved. In particular, the first operation (4-1, 5-1,
(Refer to the data of 6-1), although the deposition rate and the film thickness uniformity in the substrate slightly fluctuate, it can be seen that they are extremely improved as compared with the data of the prior art shown in FIG. Understand.

This effect is a result obtained by setting the standby state of the apparatus under the atmospheric pressure. The gas to be introduced is not limited to N ₂ , but may be another gas. In No. 3, good results were obtained by using O ₂ as the gas to be introduced when the apparatus was on standby and bringing it into atmospheric pressure.

Embodiment 2 In this embodiment, the present invention is applied to a case where a Ta ₂ O ₅ thin film is formed as a dielectric of a capacitor in the manufacture of a semiconductor device in the same manner as shown in FIG. Is applied. That is, here, O ₂ is introduced into the reaction chamber before the Ta ₂ O ₅ thin film is formed. In this case, the introduction was not performed until the atmospheric pressure was reached, and the operation was carried out while maintaining a certain low pressure state.
For example, it can be carried out at about 200 Pa or less, and in this case, it can be carried out at about 200 to 40 Pa.

In this embodiment of the present invention, the film formation characteristics are greatly improved in the embodiment, but the film formation characteristics are changed in the first operation after the standby, and the mechanism is explained. It is derived by consideration.
Hereinafter, such background consideration will be described first.

In forming a thin film in a CVD apparatus,
The deposition rate fluctuates after standing and the film thickness uniformity in the substrate
Consider the factors that make it worse. The two phenomena appear simultaneously
As a factor, fluctuations in the amount of reactant gas supplied to the substrate are considered.
It is. That is, the supply amount of the reaction gas to the substrate decreases.
May be a factor. At present, Ta _Two 
O_Five CVD equipment for forming thin films is mainly mounted on DRAM
Developed for the purpose of forming the dielectric film of the capacitive element
I have. In DRAM, the area occupied by the capacitive element in the substrate
In order to increase the capacitance value while reducing the
And the three-dimensional structure represented by the stack type
The area is secured. Thus, the surface of the substrate to be processed is large.
In order to form a structure having a large step, the dielectric film Ta
_Two O_Five For forming a thin film, high step coverage is required.
Therefore, the film forming conditions of the low pressure CVD apparatus are limited to the supply rate controlling region.
It is in. Therefore, the supply amount of the reaction gas to the substrate may change.
Means that it has a significant effect on the film formation characteristics.
Reconcile as the assumed cause of the problem described.

The reason why the supply amount of the reaction gas to the substrate is reduced may be that the reaction gas introduced into the reaction chamber is adsorbed to a portion other than the substrate. The mode adopted in the present embodiment is based on the knowledge that the above-described problem has occurred due to such a phenomenon.
The specific contents are described below.

The reaction chamber of a batch type reduced pressure CVD apparatus is generally made of quartz. In order to simplify the structure of the apparatus and to uniformly and stably supply the reaction gas to the substrate in the reaction chamber, it is preferable that the reaction gas has a structure in which turbulence and stagnation do not easily occur in the vicinity of the substrate. Therefore, for example, FIG.
A vertical reaction chamber as shown in FIG. FIG. 7 shows the structure of a general vertical reaction chamber.

Referring to FIG. The reaction chamber 11 is formed airtight from an outer tube 12, a base plate 13, and a loader 14, and a gas supply port 15 and an exhaust port 15 are located below the reaction chamber 11. In order to stably and uniformly supply the reaction gas to the transport boat 18 loaded with the substrate 17, a structure having an inner tube 19 is adopted. Here, the surface of the outer tube 12 and the inner tube 19 occupying overwhelming areas can be considered as the site where the reaction gas is adsorbed, which is assumed as the cause of the problem in forming the Ta ₂ O ₅ thin film.

Here, only in the first operation after the standby of the apparatus,
The reason why the reaction gas is adsorbed on the surface of the reaction chamber will be considered. When a Ta ₂ O ₅ thin film is actually formed by the CVD apparatus having the above structure, the entire reaction chamber 11 is heated by a heater as the heating means 20 shown in FIG. Due to such a hot wall type structure, a reactant also accumulates on the surface of the reaction chamber.
Also, as described above, the atmosphere in the furnace during the standby time of the apparatus is under reduced pressure in the prior art, and the difference between the first operation after standby and the second and subsequent operations when continuous operation is performed. Is the time during which the reaction chamber is kept under reduced pressure after the Ta ₂ O ₅ thin film is formed until the next film formation.

From the above, the mechanism by which the above problem occurs is considered as follows. By keeping the reaction chamber under reduced pressure, reactants deposited on the inner surface of the reaction chamber are desorbed. The manner of this desorption is considered to depend on the time during which the reaction chamber is left under reduced pressure. Strictly, it depends on the degree of vacuum in the reaction chamber. However, in the standby state of the apparatus, the degree of vacuum is usually maintained at a constant level.

Here, the reactants deposited on the surface of the reaction chamber will be considered. The gas supplied to the reaction chamber is a reaction gas containing Ta (Ta (OC ₂ H ₅ ) ₅ and O ₂ in this example, and an inert gas such as N ₂ may be supplied in some cases. The reactants deposited in the reaction chamber are composed of multiple atoms, and the desorption of the reactants is unlikely to proceed uniformly on the surface of the reaction chamber. At this time, it is considered that the desorption under reduced pressure does not proceed evenly for each atom, but depends on the type of the atom, and as a countermeasure against this, it is effective to reduce the desorption of this reactant. Therefore, it is considered that maintaining the reaction chamber at the atmospheric pressure during the standby time of the apparatus as in Embodiment 1 was effective for stabilizing the film forming characteristics. Develop other means to stabilize film properties

As described above, if it is considered that the desorption of a reactant proceeds selectively depending on its constituent atoms, the desorption of the reactant deposits on the surface of the reaction chamber after the desorption occurs by maintaining the pressure under reduced pressure. Some substances are considered to be unstable due to their desorption. In this case, by improving the desorbed substance before forming the Ta ₂ O ₅ thin film, the improvement of the film forming characteristics can be achieved. It is better to avoid introducing a source gas containing Ta after inserting the substrate to be processed into the reaction chamber from the viewpoint of particles and the like. Here, before forming the Ta ₂ O ₅ thin film, O ₂
Was independently introduced. FIG. 5 shows the film forming characteristics confirmed in this case. FIG. 5 corresponds to FIG.
FIG. 8 corresponds to FIG. 8 and is a result of measurement performed in the same manner.

Specifically, in this example, in the conventional film forming process in which a substrate to be processed is inserted into a reaction chamber to form a thin film, before the actual film forming process, O ₂ is introduced into the reaction chamber.
Are added for 20 minutes. As O _2, industrially pure, dry O ₂ used in the manufacture of semiconductor devices was used. The O ₂ flow rate is preferably as large as possible in order to enhance the effect of O ₂ introduction. However, it is necessary to maintain the degree of vacuum, so the O ₂ flow rate is preferably 1 SLM or less. Here, it was set to about 1 SLM.

This step of introducing O ₂ alone is intended to supplement the reactants desorbed from the surface of the reaction chamber based on the above considerations. Therefore, the effect is not limited to O ₂ , as long as the gas supplements the reactant desorbed from the surface of the reaction chamber. In addition, the introduction time may be appropriately set in consideration of the specifications and the use state of the apparatus, and is not limited to 20 minutes. This processing time is preferably performed within a range of 5 minutes to 120 minutes. Under normal conditions, the effect of introduction is not sufficient for less than 5 minutes, and the treatment for more than 120 minutes is disadvantageous in terms of productivity and the effect is not necessarily increased accordingly. From the viewpoint of both properties, it is preferable to set the range.

In a low pressure CVD apparatus, it takes time to stabilize the temperature. Therefore, before the step of actually forming a film,
Since the step of stabilizing the temperature is usually performed, by introducing O ₂ during this temperature stabilizing step, the productivity can be increased. By also introducing O ₂ during the temperature stabilization step, it is not necessary to take a special time for introducing O ₂ , thereby increasing the productivity. That is, it is preferable to introduce the O ₂ after the substrate to be processed is inserted into the reaction chamber, particularly during the temperature stabilization step.

[0069] As described above, if the gas to compensate for the reactant desorbed from the reaction chamber surfaces, the introduction gas is not limited to O _2, remarkable effect shown in FIG. 5 seen by O ₂ introduction , O ₂ introduction is a preferred embodiment.

Embodiment 3 This embodiment is directed to a case where a Ta ₂ O ₅ thin film is formed as a dielectric of a capacitor in the manufacture of a semiconductor device in the same manner as shown in FIG. Is applied. In other words, here, O
₂ alone and maintained at atmospheric pressure,
O ₂ was introduced into the reaction chamber before the formation of the ₂ O ₅ thin film. That is, this example is the same as that in the first embodiment (however, in this case, N 2 is used as a gas for keeping the apparatus at standby at atmospheric pressure).
₂ is used instead of ₂ ) and the second embodiment. According to this embodiment, a result equivalent to that of the second embodiment, or a result in which the deposition rate and the in-plane film thickness uniformity were further improved was obtained.

Each of the above embodiments is a technique capable of obtaining generally stable film formation characteristics with respect to the formation of a high melting point metal oxide by a hot wall type reduced pressure CVD apparatus. It is not limited to a vertical or other device type. The same effect can be obtained for a single-wafer apparatus.

In each of the above embodiments, the hot
High melting point metal
In the case of forming an oxide, Ta is an effective material.
_Two O _Five Do not deteriorate productivity when depositing
In addition, stable film formation characteristics can be obtained. this
The oxide of refractory metal, especially Ta_Two O_Five Take a thin film
Electronic material used, for example, this is used as a dielectric film
Of the characteristics of the capacitive element
Improved neutrality was realized.

[0073]

As described above, according to the present invention, it is possible to improve the film forming characteristics and suppress variations in the characteristics of the product (for example, variations in the characteristics of the capacitive element in the product) while securing the productivity. The present invention has provided a CVD apparatus and a method for manufacturing a semiconductor device which can improve the concentration of product characteristics.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a preferred embodiment of the present invention.

FIG. 2 is a flowchart showing a preferred embodiment of the present invention.

FIG. 3 is a flowchart showing a preferred embodiment of the present invention.

FIG. 4 is a diagram illustrating an operation of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an operation of the second embodiment of the present invention.

FIG. 6 is a view showing a schematic configuration of a hot wall type reduced pressure CVD apparatus used for film formation.

FIG. 7 is a diagram showing a general structure of a vertical reaction chamber of a low pressure CVD apparatus.

FIG. 8 is a diagram showing a problem of the related art.

[Description of References] I: O ₂ introduction step (before the film forming step), II: Film forming step, III: Atmospheric pressure holding step in a device standby state, IV: (next ) Film formation process.

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Claims (27)

[Claims] 1. A hot wall type CVD apparatus for depositing a refractory metal oxide under reduced pressure, wherein the reaction chamber is maintained at an atmospheric pressure during a standby state other than when the apparatus is operated. . 2. In order to maintain the reaction chamber at atmospheric pressure,
The CVD apparatus according to claim 11, wherein oxygen is introduced into the reaction chamber. 3. The CVD apparatus according to claim 1, wherein the oxide of the refractory metal is a tantalum oxide. 4. A hot wall type CVD apparatus for forming a high melting point metal oxide film under reduced pressure, wherein a deposit adhering to an inner surface of a reaction chamber is removed before the film forming step. A CVD apparatus for supplying a substance desorbed from a deposit. 5. The CVD apparatus according to claim 4, wherein the substance to be supplied is oxygen. 6. The CVD apparatus according to claim 4, wherein the oxide of the high melting point metal is an oxide of tantalum. 7. A hot wall type CVD apparatus for forming a high melting point metal oxide film under reduced pressure, characterized in that a gas containing oxygen is introduced into a reaction chamber before the film forming step. CVD equipment. 8. The CVD apparatus according to claim 7, wherein the introduction of the gas containing oxygen into the reaction chamber is performed after the substrate on which the film is to be formed is inserted into the reaction chamber. 9. The method according to claim 7, wherein the introduction of the gas containing oxygen into the reaction chamber is performed when the substrate to be formed is inserted into the reaction chamber to stabilize the temperature of the substrate. 3. The CVD apparatus according to claim 1. 10. The CVD apparatus according to claim 7, wherein the introduction of the oxygen-containing gas into the reaction chamber is performed within 5 minutes to 120 minutes. 11. The CVD according to claim 7, wherein the oxide of the high melting point metal is an oxide of tantalum.
apparatus. 12. A hot-wall type CVD apparatus for depositing a high-melting-point metal oxide film under reduced pressure, wherein an oxygen-containing gas is introduced into a reaction chamber before the film-forming step, and an operation of the apparatus is performed. A CVD apparatus characterized in that a reaction chamber is maintained at an atmospheric pressure during a standby state other than at a time. 13. The method according to claim 1, wherein oxygen is introduced into the reaction chamber to maintain the reaction chamber at atmospheric pressure.
3. The CVD apparatus according to 2. 14. The CV according to claim 12, wherein the oxide of the refractory metal is a tantalum oxide.
D device. 15. A method for manufacturing a semiconductor device, comprising a step of forming an oxide of a high melting point metal under reduced pressure using a hot wall type CVD apparatus, wherein the CVD apparatus is in a standby state other than when the apparatus is operating. A method for manufacturing a semiconductor device, wherein the reaction chamber is sometimes maintained at atmospheric pressure. 16. The method of manufacturing a semiconductor device according to claim 15, wherein the oxide of the refractory metal is an oxide of tantalum. 17. A method for manufacturing a semiconductor device having a step of forming an oxide of a refractory metal under reduced pressure using a hot-wall type CVD apparatus, wherein a reaction is performed before the step of forming a film by the CVD apparatus. A method for manufacturing a semiconductor device, comprising: supplying a substance desorbed from a deposit to a deposit attached to an inner surface of a chamber. 18. The method according to claim 17, wherein the substance to be supplied is oxygen. 19. The method for manufacturing a semiconductor device according to claim 17, wherein the oxide of the refractory metal is a tantalum oxide. 20. A method of manufacturing a semiconductor device, comprising: forming a high-melting-point metal oxide film under reduced pressure by using a hot-wall type CVD device. A method for manufacturing a semiconductor device, comprising introducing a gas containing oxygen into a room. 21. The method according to claim 20, wherein the oxide of the refractory metal is a tantalum oxide. 22. A method of manufacturing a semiconductor device comprising a step of forming a high-melting-point metal oxide film under reduced pressure by using a hot-wall type CVD apparatus, the method comprising the steps of: A method for manufacturing a semiconductor device, comprising introducing a gas containing oxygen into a chamber and maintaining the reaction chamber at atmospheric pressure in a standby state other than when the apparatus is operating. 23. The method according to claim 2, wherein oxygen is introduced into the reaction chamber to maintain the reaction chamber at atmospheric pressure.
3. The method for manufacturing a semiconductor device according to item 2. 24. The method according to claim 22, wherein the oxide of the refractory metal is a tantalum oxide. 25. A method for manufacturing a semiconductor device comprising a step of forming a high-melting-point metal oxide film under reduced pressure using a hot-wall type CVD device, wherein a substrate to be formed is inserted into a reaction chamber of the CVD device. Before the step, a step of forming a film of a high-melting-point metal oxide is performed so as to cover the inner surface of the reaction chamber. A method of manufacturing a semiconductor device, comprising: inserting a semiconductor device; 26. The method according to claim 25, wherein the oxide of the refractory metal is a tantalum oxide. 27. The step of forming a film of a high-melting-point metal oxide so as to cover the inner surface of the reaction chamber during the step of loading a substrate to be formed into a transfer boat inserted into the reaction chamber. The method of manufacturing a semiconductor device according to claim 25, wherein: