Method and apparatus for forming silicon oxide film

A silicon oxide film forming method includes: forming an amorphous silicon film, including: adsorbing an adsorbate containing silicon to a workpiece by supplying a source gas containing chlorine and silicon into a reaction chamber accommodating the workpiece, activating the source gas, and reacting the activated source gas with the workpiece; and removing chlorine contained in the adsorbate by supplying hydrogen gas into the reaction chamber and activating the hydrogen gas, and reacting the activated hydrogen gas with the adsorbate, wherein removing the chlorine is performed after adsorbing the adsorbate is performed, thereby forming the amorphous silicon film on the workpiece; and forming a silicon oxide film on the workpiece by supplying an oxidizing gas into the reaction chamber and oxidizing the amorphous silicon film, wherein forming the amorphous silicon film and forming the silicon oxide film are repeated in this order plural times.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application Nos. 2014-029085 and 2014-232631, respectively filed on Feb. 19 and Nov. 17, 2014, in the Japan Patent Office, the disclosure of which is incorporated herein in their entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus for forming a silicon oxide film.

BACKGROUND

As a method of forming a silicon oxide film, there is proposed atomic layer deposition (ALD) for forming a high-quality silicon oxide film on a workpiece, for example, a semiconductor wafer, at low temperature. For example, a method of forming a thin film at a low temperature of 300 degrees C. to 600 degrees C. is widely known in the art.

As this kind of silicon oxide film, there is a demand for a high-quality silicon oxide film to have high density of Si within its film. Therefore, there is a need for a method of forming a silicon oxide film capable of densifying Si.

SUMMARY

Some embodiments of the present disclosure provide a method and apparatus for forming a silicon oxide film having a high density of Si.

According to one embodiment of the present disclosure, there is provided a silicon oxide film forming method including: forming an amorphous silicon film, including: adsorbing an adsorbate containing silicon to a workpiece by supplying a source gas containing chlorine and silicon into a reaction chamber accommodating the workpiece, activating the source gas, and reacting the activated source gas with the workpiece; and removing chlorine contained in the adsorbate by supplying hydrogen gas into the reaction chamber and activating the hydrogen gas, and reacting the activated hydrogen gas with the adsorbate, wherein removing the chlorine is performed after adsorbing the adsorbate is performed, thereby forming the amorphous silicon film on the workpiece; and forming a silicon oxide film on the workpiece by supplying an oxidizing gas into the reaction chamber and oxidizing the amorphous silicon film, wherein forming the amorphous silicon film and forming the silicon oxide film are repeated in this order plural times.

According to another embodiment of the present disclosure, there is provided an apparatus for forming a silicon oxide film, including: a reaction chamber configured to accommodate a workpiece; a source gas supply unit configured to supply a source gas containing chlorine and silicon into the reaction chamber; a hydrogen gas supply unit configured to supply hydrogen gas into the reaction chamber; an oxidizing gas supply unit configured to supply an oxidizing gas into the reaction chamber; and a controller configured to control the respective units of the apparatus, wherein the controller controls the source gas supply unit to supply the source gas into the reaction chamber such that an adsorbate containing silicon is adsorbed to the workpiece accommodated in the reaction chamber, and controls the hydrogen gas supply unit to supply the hydrogen gas into the reaction chamber such that chlorine contained in the adsorbate is removed, thereby forming an amorphous silicon film on the workpiece, wherein the controller controls the oxidizing gas supply unit to supply the oxidizing gas into the reaction chamber such that the silicon amorphous silicon film is oxidized, thereby forming a silicon oxide film on the workpiece, wherein the controller repeats forming the amorphous silicon film and forming the silicon oxide film plural times.

DETAILED DESCRIPTION

A method and apparatus for forming a silicon oxide film according to some embodiments of the present disclosure will now be described in detail. In the present embodiments, the description will be given by way of example in which a batch-type vertical processing apparatus is used as the apparatus for forming a silicon oxide film according to the embodiments of the present disclosure.FIG. 1shows the configuration of the processing apparatus according to one embodiment.

Referring toFIG. 1, the processing apparatus1includes a reaction tube2that extends in a longitudinal direction, which is the vertical direction. The reaction tube2has a double tube structure which includes an inner tube2aand a roofed outer tube2bconfigured to cover the inner tube2aand separated a predetermined distance from the inner tube2a. Sidewalls of the inner tube2aand the outer tube2bhave a plurality of openings as indicated by arrows inFIG. 1. The inner tube2aand the outer tube2bare made of a material having excellent heat resistance and corrosion resistance, for example, quartz.

The reaction tube2is provided at one side thereof with an exhaust unit3that exhausts gas from the reaction tube2. The exhaust unit3extends upward along the reaction tube2and communicates with the reaction tube2through the openings formed in the sidewall of the reaction tube2. The exhaust unit3is connected at an upper end thereof to an exhaust port4arranged at an upper portion of the reaction tube2. An exhaust pipe (not shown) is connected to the exhaust port4. Pressure regulating mechanisms such as a valve (not shown) and a vacuum pump127described below are disposed in the exhaust pipe. By virtue of the pressure regulating mechanisms, a gas supplied from the sidewall of one side of the outer tube2b(a source gas supply pipe8) is exhausted to the exhaust pipe through the inner tube2a, the sidewall of the other side of the outer tube2b, the exhaust unit3, and the exhaust port4. Thus, the interior of the reaction tube2is controlled to a desired pressure (vacuum degree).

A lid5is disposed under the reaction tube2. The lid5is made of a material having excellent heat resistance and corrosion resistance, for example, quartz. The lid5may be moved up and down by a boat elevator128described below. When the lid5is moved up by the boat elevator128, a lower end (furnace port) of the reaction tube2is closed. When the lid5is moved down by the boat elevator128, the lower end (furnace port) of the reaction tube2is open.

A wafer boat6is loaded on the lid5. The wafer boat6is made of, for example, quartz. The wafer boat6is configured to accommodate a plurality of semiconductor wafers W such that the plural semiconductor wafers W are separated a predetermined distance from each other in the vertical direction. Furthermore, a heat insulating container or a rotary table may be disposed on the lid5, and the wafer boat6may be mounted thereon. The heat insulating container prevents reduction in internal temperature of the reaction tube2at the furnace port of the reaction tube2and the wafer boat6for accommodating the semiconductor wafers W may be rotatably loaded on the rotary table. In this case, it is easy to control the semiconductor wafers W accommodated within the wafer boat6at the uniform temperature.

In the vicinity of the reaction tube2, temperature rising heaters7, for example, consisting of resistive heating elements, are disposed so as to surround the reaction tube2. The interior of the reaction tube2is heated to a predetermined temperature by the temperature rising heaters7. As a result, the semiconductor wafers W accommodated within the reaction tube2are heated to a predetermined temperature.

The source gas supply pipe8for supplying a source gas into the reaction tube2(the outer tube2b) is inserted into the reaction tube2through a side surface near the lower end of the reaction tube2. The source gas is a Si source which supplies a source material (Si) to be adsorbed to a workpiece. The source gas is used in an adsorption step described below. Examples of the Si source may include a gas containing chlorine (Cl) and silicon (Si), for example, hexachlorodisilane (HCD: Si2Cl6), octachlorotrisilane (Si3Cl8), and tetrachlorosilane (SiCl4). In this example, HCD is used as the Si source.

A plurality of supply holes is formed in the source gas supply pipe8to be arranged at certain intervals in the vertical direction. The source gas is supplied into the reaction tube2(the outer tube2b) through the supply holes. Thus, as indicated by arrows inFIG. 1, the source gas is supplied into the reaction tube2from a plurality of points arranged in the vertical direction.

A hydrogen gas supply pipe9for supplying hydrogen (H2) gas into the reaction tube2(the outer tube2b) is inserted into the reaction tube2through the side surface near the lower end of the reaction tube2. The hydrogen gas is a gas which removes chlorine from the adsorbed source to form amorphous silicon (a-Si) film. The hydrogen gas is used in a chlorine removal step described below.

An oxidizing gas supply pipe10for supplying an oxidizing gas into the reaction tube2(the outer tube2b) is inserted into the reaction tube2through the side surface near the lower end of the reaction tube2. The oxidizing gas is a gas which oxidizes the a-Si film. The oxidizing gas is used in an oxidation process described below. Examples of the oxidizing gas may include hydrogen (H2)+oxygen (O2), O2plasma, and oxygen radicals used in O3treatment or the like, in addition to oxygen (O2), ozone (O3), nitrogen oxide (NO), dinitrogen monoxide (N2O). In this example, oxygen (O2) is used as the oxidizing gas.

A nitrogen gas supply pipe11for supplying nitrogen (N2) as a diluting gas and a purge gas into the reaction tube2(the outer tube2b) is inserted into the reaction tube2through the side surface near the lower end of the reaction tube2.

The source gas supply pipe8, the hydrogen gas supply pipe9, the oxidizing gas supply pipe10, and the nitrogen gas supply pipe11are connected to gas supply sources (not shown) through MFCs (Mass Flow Controllers)125described below.

A plurality of temperature sensors122, for example, consisting of thermocouples, for measuring the internal temperature of the reaction tube2and a plurality of pressure gauges123for measuring the internal pressure of the reaction tube2are disposed within the reaction tube2.

The processing apparatus1further includes a controller100configured to control the respective components of the apparatus.FIG. 2shows the configuration of the controller100. As shown inFIG. 2, a manipulation panel121, the temperature sensors122, the pressure gauges123, a heater controller124, the MFCs125, valve controllers126, the vacuum pump127, the boat elevator128and the like are connected to the controller100.

The manipulation panel121is provided with a display and manipulation buttons. The manipulation panel121transmits operating instructions to the controller100and displays a variety of information received from the controller100on the display thereof.

The temperature sensors122measure the temperatures of the respective components within the reaction tube2, the exhaust pipe, etc., and notify the controller100of the measured values.

The pressure gauges123measure the pressures of the respective components within the reaction tube2, the exhaust pipe, etc., and notify the controller100of the measured values.

The heater controller124individually controls the temperature rising heaters7. In response to instructions received from the controller100, the heater controller124allows supply of electric current to the temperature rising heaters7to heat the temperature rising heaters7. Moreover, the heater controller124measures power consumption of the respective temperature rising heaters7and notifies the controller100of the measured values.

The respective MFCs125are disposed in the pipes such as the source gas supply pipe8, the hydrogen gas supply pipe9, the oxidizing gas supply pipe10, and the nitrogen gas supply pipe11. The MFCs125control flow rates of gases flowing through the respective pipes at rates instructed by the controller100. At the same time, the MFCs125measure the actual flow rates of the gases and notify the controller100of the measured flow rates.

The valve controllers126are disposed in the respective pipes and control the opening degrees of the valves disposed in the respective pipes at the values instructed by the controller100.

The vacuum pump127is connected to the exhaust pipe and exhausts the gas present within the reaction tube2.

The boat elevator128moves the lid5upward to load the wafer boat6(the semiconductor wafers W) into the reaction tube2. The boat elevator128moves the lid5downward to unload the wafer boat6(the semiconductor wafers W) from the interior of the reaction tube2.

The controller100includes a recipe storage unit111, a read only memory (ROM)112, a random access memory (RAM)113, an input/output (I/O) port114, a central processing unit (CPU)115, and a bus116interconnecting these components to one another.

A setup recipe and a plurality of process recipes are stored in the recipe storage unit111. In the beginning of manufacture of the processing apparatus1, only the setup recipe is stored in the recipe storage unit111. The setup recipe is executed to generate thermal models and the like for individual processing apparatuses. The process recipe is prepared for each heat treatment (process) actually performed by a user. Each of the process recipes regulates temperature changes of the respective components, pressure changes within the reaction tube2, and supply start/stop timings and supply amounts of various types of gases, during the time period from when the semiconductor wafers W are loaded into the reaction tube2to when the processed semiconductor wafers W are unloaded from the reaction tube2.

The ROM112is constituted by an electrically erasable programmable read only memory (EEPROM), a flash memory, a hard disk or the like. The ROM112is a recording medium that stores an operation program of the CPU115and the like.

The RAM113serves as a work area of the CPU115.

The I/O port114is connected to the manipulation panel121, the temperature sensors122, the pressure gauges123, the heater controller124, the MFCs125, the valve controllers126, the vacuum pump127, the boat elevator128, and the like. The I/O port114controls the input and output of data or signals.

The CPU115constitutes a core of the controller100and executes operation programs stored in the ROM112. In response to instructions received through the manipulation panel121, the CPU115controls operation of the processing apparatus1according to the recipes (process recipes) stored in the recipe storage unit111. That is to say, the CPU115allows the temperature sensors122, the pressure gauges123, the MFCs125, etc., to measure the temperatures, pressures, flow rates, etc. of the respective components within the reaction tube2, the exhaust pipe, etc. Based on the measurement data, the CPU115outputs control signals to the heater controller124, the MFCs125, the valve controllers126, the vacuum pump127and the like, thereby controlling the respective components to follow the process recipes.

The bus116delivers information between the respective components.

Next, a method of forming a silicon oxide film using the processing apparatus1configured as above will be described with reference to the recipe (time sequence) shown inFIG. 3. In the method of forming a silicon oxide film according to the present embodiment, a silicon oxide film is formed on a semiconductor wafer W by ALD.

Referring toFIG. 3, ALD according to one embodiment of the present disclosure includes: an a-Si film forming process for forming an amorphous silicon (a-Si) film by repeating an adsorption step for adsorbing a source (Si) to a semiconductor wafer W and a chlorine removal step for removing chlorine (Cl) from the adsorbed source plural times; and a oxidation process for oxidizing the formed a-Si film (forming a silicon oxide film). The a-Si film forming process and the oxidation process are performed (repeated) plural times, for example, one hundred times, whereby a silicon oxide film having a desired thickness is formed on the semiconductor wafer W. In addition, in this embodiment, as shown inFIG. 3, hexachlorodisilane (HCD), hydrogen (H2), oxygen (O2), and nitrogen (N2) are used as a Si source gas, hydrogen gas, an oxidizing gas, and a diluting gas, respectively.

In the following description, operations of the respective components constituting the processing apparatus1are controlled by the controller100(the CPU115). The controller100(the CPU115) controls the heater controller124(the temperature rising heaters7), the MFCs125(the source gas supply pipe8and the like), the valve controllers126, and the vacuum pump127in the aforementioned manner, such that the temperature, pressure, flow rates of gases, etc. in the reaction tube2in the respective processes are set to conditions conforming to the recipe shown inFIG. 3.

First, the interior of the reaction tube2is maintained at a predetermined load temperature, for example, 300 degrees C., by the temperature rising heaters7, as shown in (a) ofFIG. 3. Then, the wafer boat6accommodating the semiconductor wafers W is loaded onto the lid5. The lid5is moved up by the boat elevator128, thereby loading the semiconductor wafers W (the wafer boat6) into the reaction tube2(load process).

Subsequently, the adsorption step for adsorbing a source to the semiconductor wafer W is performed. First, the interior of the reaction tube2is set at a predetermined temperature, for example, 600 degrees C. as shown in (a) ofFIG. 3, using the temperature rising heaters7. Further, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2while discharging the gas within the reaction tube2. Thus, the reaction tube2is set to a predetermined pressure, for example, 133 Pa (1 Torr), as shown in (b) ofFIG. 3(stabilization process).

In this regard, the internal temperature of the reaction tube2may range from 500 degrees C. to 700 degrees C., or from 550 degrees C. to 650 degrees C. These temperature ranges can improve the film quality of the formed silicon oxide film, the uniformity of the film thickness, etc.

The internal pressure of the reaction tube2may range from 0.133 Pa (0.001 Torr) to 13.3 kPa (100 Torr) in some embodiments. This pressure range can accelerate the reaction of Si with the semiconductor wafer W. The internal pressure of the reaction tube2, in some embodiments, may range from 133 Pa (1 Torr) to 1330 Pa (10 Torr). That is because this pressure range can make it easier to control the internal pressure of the reaction tube2.

Subsequently, the a-Si film forming process for forming an amorphous Si (a-Si) film on the semiconductor wafer W is performed. The a-Si film forming process includes the adsorption step for adsorbing Si to the semiconductor wafer W and the chlorine removal step for removing chlorine (Cl) from the adsorbed source on the semiconductor wafer W. The adsorption step and the chlorine removal step are repeated plural times, whereby the a-Si film is formed on the semiconductor wafer W.

First, the adsorption step is performed. In the adsorption step, a specific amount of HCD is supplied as a Si source from the source gas supply pipe8into the reaction tube2, as shown in (d) ofFIG. 3, and a predetermined amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2, as shown in (c) ofFIG. 3(flow process).

HCD supplied into the reaction tube2is heated and activated within the reaction tube2. For this reason, upon supplying HCD into the reaction tube2, the activated Si reacts with the semiconductor wafer W and is adsorbed to the semiconductor wafer W.

When a predetermined amount of Si is adsorbed to the semiconductor wafer W, supply of HCD from the source gas supply pipe8and supply of nitrogen from the nitrogen gas supply pipe11are stopped. Then, for example, as shown in (c) ofFIG. 3, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2such that the gas within the reaction tube2is discharged outside of the reaction tube2(purge/vacuum process).

Subsequently, the chlorine removal step is performed. In the chlorine removal step, first, the internal temperature of the reaction tube2is set to a predetermined temperature, for example, 600 degrees C. as shown in (a) ofFIG. 3, using the temperature rising heaters7. Further, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2while discharging the gas from the reaction tube2. Thus, the internal pressure of the reaction tube2is set to a predetermined pressure, for example, 133 Pa (1 Torr), as shown in (b) ofFIG. 3. Then, a specific amount of hydrogen gas is supplied from the hydrogen gas supply pipe9into the reaction tube2, as shown in (e) ofFIG. 3, and a predetermined amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2, as shown in (c) ofFIG. 3(flow process).

Hydrogen supplied into the reaction tube2is heated and activated within the reaction tube2. For this reason, upon supplying hydrogen into the reaction tube2, the activated hydrogen severs Si—Cl bonds of the adsorbed Si to remove chlorine from the adsorbed source.

In this regard, a process of supplying hydrogen radicals into the reaction tube2is considered as a method of removing chlorine from the adsorbed source. However, the removal of chlorine with hydrogen radicals causes not only Si—Cl bonds of the adsorbed Si but also Si—Si bonds thereof to be severed. Thus, an amorphous silicon (a-Si) film containing a large amount of hydrogen (H) is formed on the semiconductor wafer W, which disrupts densification of Si. Accordingly, hydrogen gas is used to remove chlorine from the adsorbed source.

When chlorine is removed from the adsorbed source, supply of hydrogen gas from the hydrogen gas supply pipe9and supply of nitrogen from the nitrogen gas supply pipe11are stopped. Then, for example, as shown in (c) ofFIG. 3, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2such that the gas within the reaction tube2is discharged from the reaction tube2(purge/vacuum process).

As a result, an amorphous silicon (a-Si) film is formed on the semiconductor wafer W. Subsequently, the adsorption step and the chlorine removal step are repeated a predetermined number of times. Consequently, an a-Si film having a desired thickness is formed on the semiconductor wafer W (a-Si film forming process).

Subsequently, the process for oxidizing the formed a-Si film (for forming a silicon oxide film) is performed. First, in the oxidation process, the internal temperature of the reaction tube2is set to a predetermined temperature, for example, 600 degrees C., using the temperature raising heaters7, as shown in (a) ofFIG. 3. Further, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2while discharging the gas from the reaction tube2. Thus, the internal pressure of the reaction tube2is set to a predetermined pressure, for example, 133 Pa (1 Torr), as shown in (b) ofFIG. 3. Then, a specific amount of oxygen gas is supplied from the oxidizing gas supply pipe10into the reaction tube2, as shown in (f) ofFIG. 3, and a predetermined amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2, as shown in (c) ofFIG. 3(flow process).

Oxygen supplied into the reaction tube2is heated and activated within the reaction tube2. For this reason, upon supplying oxygen into the reaction tube2, the formed a-Si film is oxidized. As a result, a silicon oxide film (SiO2) film is formed on the semiconductor wafer W.

When the silicon oxide film (SiO2) film is formed on the semiconductor wafer W, supply of oxygen gas from the oxidizing gas supply pipe10and supply of nitrogen from the nitrogen gas supply pipe11are stopped. Then, for example, as shown in (c) ofFIG. 3, a specific amount of nitrogen is supplied from the nitrogen gas supply pipe11into the reaction tube2such that the gas within the reaction tube2is discharged from the reaction tube2(purge/vacuum process).

Accordingly, one cycle of ALD including the a-Si film forming process and the oxidation process is finished. Subsequently, another cycle of ALD may be started from the adsorption step in the a-Si film forming process, and such a cycle may be repeated a predetermined number of times. In this manner, a silicon oxide film having a desired thickness is formed on the semiconductor wafer W.

When the silicon oxide film having a desired thickness is formed on the semiconductor wafer W, the interior of the reaction tube2is maintained at a predetermined loading temperature, for example, 300 degrees C., using the temperature raising heaters7, as shown in (a) ofFIG. 3, while supplying a specific amount of nitrogen from the nitrogen gas supply pipe10into the reaction tube2, such that the interior of the reaction tube2is cycle-purged with N2to be returned to normal pressure (normal pressure restoration process). Then, the lid5is moved down by the boat elevator128, thereby unloading the semiconductor wafers W (unloading process).

As such, the processes of adsorbing HCD to the semiconductor wafer W, supplying hydrogen, removing chlorine from the adsorbed source and forming the a-Si film are performed plural times, whereby densification of Si can be accomplished without relying on adsorption sites. On the other hand, in a conventional method of adsorbing a Si source to a surface of a semiconductor wafer W, since Si is adsorbed only to adsorption sites of the surface to be adsorbed, densification of Si is impossible.

In order to confirm effects of the present disclosure, with the method of forming a silicon oxide film as set forth above, a 100 nm thick silicon oxide film was formed on a semiconductor wafer W, followed by measuring Si density of the silicon oxide film. The measured value was 2.30 g/cm3or higher. For comparison, a 100 nm thick silicon oxide film was formed by the conventional method, followed by measuring Si density of the silicon oxide film. The measured value was about 2.25 g/cm3. Therefore, it was ascertained that the method of forming a silicon oxide film of the present embodiment could realize densification of Si.

As described above, according to the present embodiment, the processes of adsorbing HCD to a semiconductor wafer W, supplying hydrogen, and forming an a-Si film through removal of chlorine from the adsorbed source are performed plural times, and then oxygen is supplied to the a-Si film to form a silicon oxide film on the semiconductor wafer W through oxidation of the a-Si film, whereby the density of Si in the silicon oxide film can be increased.

The present disclosure is not limited to the aforementioned embodiment but may be modified and applied in many different forms. Hereinafter, other embodiments applicable to the present disclosure will be described.

In the aforementioned embodiment, the present disclosure has been described by way of example wherein the processes of adsorbing HCD to a semiconductor wafer W, supplying hydrogen and forming an a-Si film through removal of chlorine from the adsorbed source are performed plural times. However, the oxidation process may be performed without repeating the a-Si film forming process plural times, for example, as shown inFIG. 4. Even in this case, the density of Si in the formed silicon oxide film can be increased.

In the aforementioned embodiment, the present disclosure has been described by way of example wherein HCD is used as the Si source. However, the Si source may be a gas containing chlorine (Cl) and silicon (Si), for example, octachlorotrisilane (Si3Cl8), and tetrachlorosilane (SiCl4).

In the aforementioned embodiment, the present disclosure has been described by way of example wherein oxygen is used as the oxidizing gas. However, the oxidizing gas may be any gas capable of substituting Si—O groups for Si—H groups having been adsorbed to the semiconductor wafer W, after the chlorine removal step. For example, nitrogen oxide (NO) or dinitrogen monoxide (N2O) may be used as the oxidizing gas.

In particular, oxygen radicals may be used as the oxidizing gas in that the oxygen radicals have higher oxidation power than oxygen, whereby the densified Si can be entirely oxidized by the oxygen radicals even when all of the densified Si cannot be oxidized by oxygen.

For example, while the internal pressure of the reaction tube2is maintained at 1330 Pa (10 Torr) or less, H2+O2are supplied into the reaction tube2. The flow rate of H2is controlled in an amount of 5% to 90% based on the total flow rate of H2and O2. As such, oxygen radicals may be used as the oxidizing gas. In addition, oxygen radicals generated by oxygen (O2) plasma treatment, ozone (O3) treatment, or the like may be used as the oxidizing gas.

In the aforementioned embodiment, the present disclosure has been described by way of example wherein the internal temperature of the reaction tube2is set to 600 degrees C. However, the interior of the reaction tube2may be set to a low temperature by activating the process gas using catalysts, ultraviolet light, magnetic forces or the like.

In the aforementioned embodiment, assuming that one cycle is composed of an a-Si forming process and an oxidation process, the present disclosure has been described by way of example wherein this cycle was repeated one hundred times. As an alternative example, the number of cycles may be reduced to, for example, fifty cycles. Moreover, the number of cycles may be increased to, for example, two hundred cycles. Even in these cases, densification of Si in the formed silicon oxide film may be accomplished by adjusting, for example, the supply amount of the Si source depending upon the number of cycles. In addition, for example, in the a-Si forming process, the number of execution times of the chlorine removal step may be controlled in such a way that the chlorine removal step is omitted for the first ten times and started from the eleventh, thereby adjusting the film quality of the silicon oxide film.

In the aforementioned embodiment, the present disclosure has been described by way of example wherein the silicon oxide film is formed on the semiconductor wafer W through ALD. However, the present disclosure is not limited to ALD. Alternatively, a silicon oxide film may be formed on the semiconductor wafer W through chemical vapor deposition (CVD).

In the aforementioned embodiment, the present disclosure has been described by way of example wherein nitrogen is supplied as a diluting gas during supply of the process gas, such as HCD. Alternatively, the nitrogen may not be supplied during supply of the process gas. However, since it is easy to set the processing time and the like when nitrogen is supplied as the diluting gas, it may be preferable to supply the diluting gas. The diluting gas may be an inert gas other than the nitrogen, for example, helium (He), neon (Ne), argon (Ar), krypton (Kr) or xenon (Xe).

In the aforementioned embodiment, the present disclosure has been described by way of example wherein the batch-type processing apparatus having a double tube structure is used as the processing apparatus1. As an alternative example, the present disclosure may be applied to a batch-type processing apparatus having a single tube structure. Moreover, the present disclosure may be applied to a batch-type horizontal processing apparatus or a single-substrate-type processing apparatus.

The controller100employed in the embodiments of the present disclosure may be realized using a typical computer system instead of a dedicated computer system. For example, the controller100for performing the aforementioned processes may be configured by installing programs for executing processes into a general-purpose computer through a recording medium (a flexible disk, a compact disc-read only memory (CD-ROM), or the like) which stores the programs for performing the aforementioned processes.

The programs may be provided by arbitrary means. The programs may be provided not only by the recording medium mentioned above but also through a communication line, a communication network, a communication system or the like. In the latter case, the programs may be posted on bulletin boards (BBSs: Bulletin Board Systems) and provided through a network. The program thus provided is executed in the same manner as other application programs under the control of an operating system, thereby performing the processes described above.

The present disclosure is useful in any method and apparatus for forming a silicon oxide film.

According to the present disclosure, it is possible to provide a method and apparatus for forming a silicon oxide film having a high density of Si.