JP2009088236A - Method for forming film, apparatus for forming film, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for forming an alumina film which can lower the film formation temperature of an alumina film containing α-alumina, and to provide a storage medium wherein program for executing the method for forming the alumina film is stored. <P>SOLUTION: After a wafer W, which is an object to be processed, is placed in a treatment container 2, a material gas containing an aluminum β-diketone complex and an oxidation gas such as oxygen gas are introduced into the treatment container 2. Then, by raising the treatment ambient temperature inside the treatment container 2 to a temperature of not less than 200°C nor more than 1,000°C, the alumina film containing α-alumina is formed on the front surface of the wafer W. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a film forming method for forming an alumina film containing α-alumina (α-Al ₂ O ₃ ; aluminum oxide), a film forming apparatus, and a storage medium storing a program for executing the film forming method.

High integration and miniaturization of semiconductor devices are progressing, and device structures are also diversifying. With this trend, efforts are being made to select and develop more appropriate films in terms of characteristics and manufacturing processes. It has been poured.
For example, a memory element 100 used in a MONOS (Metal-Oxide-Nitride-Oxide-Semiconductor) type flash memory has a silicon layer (silicon substrate 110) between a source electrode 101 and a drain electrode 102 as shown in FIG. A tunnel oxide film 103, a charge trap layer 104, a blocking insulating layer 105, and a control gate 106 are stacked on top of each other (the memory element 100 in which the control gate 106 is formed of polysilicon is formed by SONOS (Silicon- Oxide-Nitride-Oxide-Semiconductor) type). The charge trap layer 104 is formed of, for example, a silicon nitride film (Si ₃ N ₄ ). As the blocking insulating layer 105, a film having a large band gap with respect to the silicon nitride film and a small leakage current is used.

  On the other hand, a conventionally used floating gate type flash memory is a so-called ONO film in which both sides of a silicon nitride film are sandwiched between silicon oxide films between a floating gate for storing charges and a control gate for applying a control voltage. Insulation is performed by a three-layer gate insulating film.

Recently, in the MONOS type memory element 100 described above, a technique using α-Al ₂ O ₃ as the blocking insulating layer 105 has been studied. α-Al ₂ O ₃ has a corundum crystal structure and is abundant in minerals, but has a band gap of about 8.8 eV, is larger than a silicon nitride film, and has a high dielectric constant. Therefore, the leakage current can be suppressed and the blocking insulating layer 105 can be preferably used. If α-Al ₂ O ₃ is used, the blocking insulating layer has a single-layer structure, so that there is an advantage that the manufacturing process can be simplified as compared with a floating gate type flash memory.

α-Al ₂ O ₃ is obtained by forming a film at a process temperature of about 300 ° C. using TMA (trimethylaluminum) as a raw material and then annealing at a high temperature of 1,100 ° C. or higher. Al ₂ O ₃ is amorphous at the stage of film formation at about 300 ° C., in order to phase transition to _α-Al 2 _{O 3} type, it is necessary to anneal at a high temperature of at least 1,100 ° C.. If the film is formed using TMA at a temperature higher than 300 ° C., the thermal decomposition temperature of TMA is low, so that the film formation speed becomes too high. TMA is consumed before reaching the thickness of the semiconductor wafer, and as a result, the film is formed only on the edge of the semiconductor wafer.

On the other hand, if the semiconductor wafer is annealed at a high temperature of 1,100 ° C., an unscheduled thermal history remains in the portion that has been laminated so far, and the activity of, for example, ion-implanted impurities changes from the design value. For this reason, the annealing temperature can be set only up to about 1000 ° C. in an actual manufacturing process, but then it becomes only γ, η, κ-Al ₂ O _{3 and the} like, and the band gap with respect to the silicon nitride film is as low as about 8.2 eV. Therefore, the targeted characteristics cannot be obtained by using α-Al ₂ O ₃ . Such process problems hinder the application of α-Al ₂ O ₃ in the gate structure of flash memory.

In Patent Document 1, aluminum chloride (AlCl ₃ ) and titanium chloride (TiCl ₄ ) are alternately reacted with water vapor in a processing vessel to form an ATO film in which alumina films and titanium oxide films are alternately stacked. A filming technique is described. However, this technique does not particularly describe a technique for forming an alumina film made of α-Al ₂ O ₃ and cannot solve the above-described problem.
JP 2001-234345 A: 0026 paragraph

  The present invention has been made under such circumstances, and an object thereof is a film forming method, a film forming apparatus, and a film forming method capable of lowering the film forming temperature of an alumina film containing α-alumina. The object is to provide a storage medium storing a program for carrying out the method.

A method for forming an alumina film according to the present invention includes a step of placing an object to be processed in a processing container,
Introducing a source gas containing a β-diketone complex of aluminum into the processing vessel;
Introducing an oxidizing gas into the processing vessel;
By heating the treatment atmosphere in the treatment vessel at a temperature range of 200 ° C. or more and 1,000 ° C. or less, the β-diketone complex and the oxidizing gas are reacted to form α-alumina on the surface of the object to be treated. And a step of forming an alumina film. Furthermore, the step of introducing the source gas into the processing container and the step of introducing the oxidizing gas into the processing container are preferably performed alternately.

  In the film formation method, the source gas is tris (dipivaloylmethanato) aluminum, tris (2,2,6,6-tetramethyl-3,5-octanedionate) aluminum, tris (isobutyrylpivalo). Containing at least one β-diketone complex selected from the group consisting of ilmethanato) aluminum, tris (diisobutyrylmethanato) aluminum, tris (acetylacetonato) aluminum, tris (hexafluoroacetylacetonato) aluminum Preferably, the oxidizing gas is selected from an oxidizing gas group consisting of oxygen gas, ozone gas, water vapor, nitrous oxide gas, nitrogen monoxide gas, and nitrogen dioxide gas.

The step of forming the alumina film is preferably performed in a pressure atmosphere within a range of 1.33 Pa to 1.01 × 10 ⁵ Pa, and the alumina film is formed in the MONOS memory element. It is preferable that the insulating film is a blocking insulating film.

Next, an alumina film forming apparatus according to another invention includes a processing container in which an object to be processed is placed;
Heating means for heating the object to be processed;
Raw material gas supply means for supplying a raw material gas containing a β-diketone complex of aluminum into the processing vessel;
Oxidizing gas supply means for supplying oxidizing gas into the processing vessel;
The object to be processed in the processing vessel is heated to a temperature range of 200 ° C. or more and 1,000 ° C. or less, and an alumina film containing α-alumina is formed on the object to be processed using the source gas and the oxidizing gas. And control means for controlling each means so as to form a film.

  Furthermore, a storage medium according to another invention is a storage medium used for an alumina film forming apparatus and storing a program that operates on a computer, and the program executes any one of the film forming methods described above. In order to do this, it is characterized by steps.

  According to the present invention, since the source gas containing the β-diketone complex of aluminum having a high thermal decomposition temperature is used, the aluminum film can be formed at a relatively high temperature of 200 ° C. to 1,000 ° C. it can. As a result, it is possible to form an alumina film containing α-alumina without undergoing a high-temperature annealing step of 1,100 ° C. or higher. For example, when this alumina film is used as a blocking insulating film of a MONOS type memory element, a band gap with respect to a charge trap layer made of a silicon nitride film or the like under the insulating film becomes large, and the memory element has a small leakage current. Can be obtained.

  Hereinafter, an embodiment in which the present invention is applied to a vertical heat treatment apparatus, which is a batch type heat treatment apparatus, will be described with reference to the longitudinal sectional view of FIG. The film forming apparatus 1 according to the present embodiment switches the source gas and the oxidizing gas and alternately supplies them into the processing container, forms one or a few atomic layers or molecular layers by the reaction of both gases, By performing this cycle a plurality of times, these layers are stacked to form a film on a semiconductor wafer (hereinafter referred to as “wafer”) W, which is an object to be processed. ALD (Atomic Layer Deposition) or MLD (Molecular It is configured as an apparatus for forming a film by a process called “layer deposition” or the like.

  In FIG. 2, reference numeral 2 denotes a reaction vessel that forms a processing vessel formed of, for example, quartz in the shape of a vertical cylinder. The lower end of the reaction vessel 2 is opened as a furnace port, A flange 22 is formed integrally with the reaction vessel 2. Below the reaction vessel 2, a lid 23 made of, for example, quartz that contacts the lower surface of the flange 22 and hermetically closes the opening 21 is provided so as to be opened and closed in a vertical direction by a boat elevator (not shown). A rotation shaft 24 is provided through the central portion of the lid 23, and a wafer boat 25 is mounted on the upper end thereof.

  The wafer boat 25 is provided with three or more, for example, four support columns 26, and a plurality of grooves (slots) are formed in the support columns 26 so that a plurality of, for example, 125 wafers W can be held in a shelf shape. Has been. However, among the 125 wafer W holding regions, a plurality of dummy wafers are held at both upper and lower ends, and the product wafer W is held in the region between them. A motor M that forms a drive unit that rotates the rotating shaft 24 is provided below the rotating shaft 24, and the motor M can rotate the entire wafer boat 25 via the rotating shaft 24. In addition, a heat retaining unit 27 is provided on the lid 23 so as to surround the rotating shaft 24.

  In the reaction vessel 2, two L-shaped injectors 31, 34, that is, a first gas injector 31 for supplying a raw material gas and a second gas injector for supplying an oxidizing gas are provided in the reaction vessel 2. It is inserted through the lower flange 22. As shown in FIG. 2, the first gas injector 31 has its tip raised to the upper end of the wafer boat 25, and this raised portion corresponds to each wafer W held on the wafer boat 24. A gas supply hole 311 is provided at the height position.

  The first gas injector 31 is connected to the source gas supply path 32 on the upstream side, and a vaporizer 331 for vaporizing the source source is provided on the further upstream side of the source gas supply path 32 via a valve V1. It has been. The vaporizer 331 is provided with a raw material source supply source 33 and a carrier gas supply source 332 made of, for example, a nitrogen gas cylinder through mass flow controllers MFC1 and MFC2 and valves V2 and V3, respectively.

  Here, the raw material gas supply path 32, the vaporizer 331, the raw material source supply source 33, the carrier gas supply source 332, the various valves V1 to V3, and the mass flow controllers MFC1 and MFC2 constitute the raw material gas supply means 3a.

（化２）に示すトリス（２，２，６，６-テトラメチル-３，５-オクタンジオナト）アルミニウム（Tris(2,2,6,6-tetramethyl-3,5-octanedionato)aluminum）、

（化３）に示すトリス（イソブチリルピバロイルメタナト）アルミニウム(Tris(2,2,6-trimethyl-3,5-heptanedionato)aluminum)、

（化４）に示すトリス（ジイソブチリルメタナト）アルミニウム（Tris(2,6-dimethyl-3,5-heptanedionato)aluminum）、

（化５）に示すトリス（アセチルアセトナト）アルミニウム（Tris(2,4-pentanedionato)aluminum）、

（化６）に示すトリス（ヘキサフルオロアセチルアセトナト）アルミニウム（Tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)aluminum）、

よりなる錯体群から選択される少なくとも一つのβ-ジケトン錯体を含む原料ソースが貯留されている。以下の説明においては、例えばトリス（ジピバロイルメタナト）アルミニウム（以下、Ａｌ（ＤＰＭ）_３と記す）を用いる場合について説明する。 In addition, the raw material source supply source 33 of the film forming apparatus 1 according to the present embodiment includes a β-diketone complex of aluminum as a raw material gas, for example, tris (dipivaloylmethanato) aluminum represented by the following chemical formula (Chemical Formula 1). (Tris (2,2,6,6-tetramethyl-3,5-heptanedionato) aluminum),

Tris (2,2,6,6-tetramethyl-3,5-octandionato) aluminum (Tris (2,2,6,6-tetramethyl-3,5-octanedionato) aluminum)

Tris (isobutyrylpivaloylmethanato) aluminum (Tris (2,2,6-trimethyl-3,5-heptanedionato) aluminum) shown in (Chemical Formula 3),

Tris (diisobutyrylmethanato) aluminum (Tris (2,6-dimethyl-3,5-heptanedionato) aluminum) shown in (Chemical Formula 4),

Tris (acetylacetonato) aluminum shown in (Chemical Formula 5),

Tris (hexafluoroacetylacetonato) aluminum (Tris (1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) aluminum)

A raw material source containing at least one β-diketone complex selected from the complex group consisting of is stored. In the following description, for example, a case where tris (dipivaloylmethanato) aluminum (hereinafter referred to as Al (DPM) ₃ ) is used will be described.

  On the other hand, the second gas injector 34 has substantially the same configuration as the first gas injector 31 described above, and is raised to the upper end portion of the wafer boat 25, and a large number of gases are included in this raised portion. A supply hole 341 is provided so that gas can be supplied to the height position of each wafer W held by the wafer boat 25.

An oxidizing gas supply path 35 is connected to the upstream side of the second gas injector 34, and an oxidizing gas supply source 37 is provided in the oxidizing gas supply path 35 via valves V4 and V5 and a mass flow controller MFC3. Yes. The oxidizing gas supply source 34 is selected from, for example, an oxidizing gas group consisting of oxygen gas, ozone gas, water vapor, nitrous oxide (N ₂ O) gas, nitrogen monoxide (NO) gas, and nitrogen dioxide (NO ₂ ) gas. An oxidizing gas such as oxygen gas is stored in the cylinder. The oxidizing gas supply path 35, the oxidizing gas supply source 37, the various valves V4 and V5, and the mass flow controller MFC3 constitute an oxidizing gas supply means 3b.

  Further, an exhaust port 4 for exhausting the inside of the reaction vessel 2 is formed above the reaction vessel 2. Connected to the exhaust port 4 is an exhaust pipe 43 having a vacuum pump 41 and pressure adjusting means 42 that can evacuate the reaction vessel 2 to a desired degree of vacuum. Around the reaction vessel 2, a heating furnace 45 provided with a heater 44 as a heating means for heating the inside of the reaction vessel 2 is provided. As the heater 44, it is preferable to use a carbon wire or the like that has no contamination and has excellent temperature rise and fall characteristics.

  The film forming apparatus 1 also includes a control unit 5 that controls operations of the heater 44, the pressure adjusting unit 42, the gas supply units 3a and 3b, and the like. The control unit 5 is composed of a computer having a CPU and a program (not shown), for example. The program includes operations necessary for film formation on the wafer W by the film formation apparatus 1, such as temperature control of the heater 44 and reaction container. A group of steps (commands) for controlling the pressure in the chamber 2 and controlling the supply amount of the processing gas and the oxidizing gas to the reaction vessel 2 is assembled. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

Next, an example of a film forming method performed using the film forming apparatus 1 will be described with reference to the sequence diagram shown in FIG. In the sequence diagram, FIG. 3 (a) shows the temperature in the reaction vessel 2, FIG. 3 (b) shows the supply amount of Al (DPM) ₃ to the reaction vessel 2, and FIG. 3 (c) shows the supply amount of oxygen gas. Is shown.

  First, a source electrode 101 and a drain electrode 102 are formed on a wafer W that is an object to be processed, for example, a P-type silicon substrate 110 as shown in FIG. 4A, and a silicon oxide film 103a to be a tunnel oxide film 103 is formed thereon. Alternatively, a predetermined number of wafers W on which the silicon nitride film 104a to be the charge trap layer 104 is stacked are held on the wafer boat 25, and then a boat elevator (not shown) is installed in the reaction vessel 2 maintained at a temperature of about 300 ° C., for example. The wafer boat 25 is loaded (loaded) by being raised.

Subsequently, when the lower end opening 21 of the reaction vessel 2 is closed by the lid 23, as shown in FIG. 3A, the temperature in the reaction vessel 2 is set at, for example, 200 ° C./min. The temperature is raised to, for example, 800 ° C. within a temperature range of ≧ ° C. and 1,000 ° C., preferably 600 ° C. and less than 1,000 ° C. For example, the exhaust is performed so that the pressure becomes, for example, about 266 Pa (2 Torr) within the range of 1.33 Pa (0.01 torr) to 1.01 × 10 ⁵ Pa (760 torr (normal pressure)) or less. For example, when film formation is performed at a temperature lower than 300 ° C., the temperature of the reaction vessel 2 before the wafer boat 25 is carried in may be maintained at a temperature lower than the film formation temperature.

When the temperature rise and exhaust in the reaction vessel 2 are completed, as shown in FIG. 3B, Al (DPM) ₃ is introduced into the reaction vessel 2 at a flow rate of, for example, 30 sccm in the range of 10 sccm to 1,000 sccm, for example. Supply for 60 seconds. Next, the gas supplied to the reaction vessel 2 is switched, and as shown in FIG. 3C, for example, an oxygen gas of 500 sccm in the range of 100 sccm to 20,000 sccm is supplied for 60 seconds, for example. Incidentally, well the ozone gas in the range of 100g~250g is adjusted to supply the raw material gas 1NM ³ if instead of the oxygen gas used ozone as the oxidizing gas, in the case of using the water vapor of 20sccm~500sccm It is good to adjust so that the water vapor | steam of a range may be supplied.

When the combination of the step of introducing Al (DPM) ₃ into the reaction vessel 2 and the step of introducing oxygen gas is taken as one cycle in this way, these steps are performed for 30 cycles, for example. The top film is formed. During this period, the inside of the reaction vessel 2 is maintained in a reduced pressure atmosphere of, for example, 266 Pa (2 Torr) by the pressure adjusting means 42, and the wafer boat 25 is rotated by the motor M. As a result of the film formation process, Al (DPM) ₃ reacts with oxygen gas in the reaction vessel 2, and an alumina film 105a is formed on the silicon nitride film 104a as shown in FIG. 4B.

Here, in the present embodiment, a β-diketone complex of aluminum such as Al (DPM) ₃ , which has a higher thermal decomposition temperature than TMA that has been conventionally used, is employed as a raw material gas. For this reason, for example, a film forming temperature in the range of 200 ° C. to 1,000 ° C., preferably higher than a conventional film forming temperature (for example, about 300 ° C.) when TMA is used, The alumina film 105a can be formed by reacting the source gas and the oxidizing gas within the range.

As explained in the background art, since when performing film formation at a low temperature TMA as material gas, Al ₂ O ₃ obtained is amorphous, to obtain an α-Al ₂ O ₃ 1, It is necessary to anneal at a high temperature of 100 ° C. or higher. In contrast to such a conventional technique, the present inventors use a β-diketone complex of aluminum which is difficult to thermally decompose, for example, 200 ° C. to 1,000 ° C., preferably 600 ° C. to 1,000 ° C. higher than the prior art. By performing film formation at a temperature, it was found that the alumina film 105a contains an α-Al ₂ O ₃ crystal structure.

Here, the film formation temperature in the range of 200 ° C. to 1,000 ° C. is a laminated structure under the alumina film 105a (P-type silicon substrate 110, silicon oxide film 103a, and silicon nitride film 104a on which the electrodes 101 and 102 are formed). The influence of heat history on Further, since α-Al ₂ O ₃ is included in the formed alumina film 105a, for example, the silicon nitride film 104a can be compared with an alumina film composed entirely of γ-Al ₂ O _3. Since the average band gap of the entire alumina film 105a is increased, the leakage current can be reduced.

The film forming apparatus 1 according to the present embodiment forms a film using a β-diketone complex of aluminum based on the above-described concept, thereby allowing α-Al ₂ O ₃ without annealing after film formation. An alumina film 105a containing can be formed.

Returning to the description of the operation of the film forming apparatus 1, when the alumina film 105a is formed on the silicon nitride film 104a by the process described above, the supply of the source gas into the reaction vessel 2 is stopped, and a nitrogen gas source (not shown) Purge is performed with N ₂ gas supplied from, and the pressure in the reaction vessel 2 is returned to normal pressure. Next, the temperature in the reaction vessel 2 is lowered to, for example, 300 ° C., and the wafer boat 25 is unloaded from the reaction vessel 2. The series of steps described above is performed by controlling the heater 44, the pressure adjusting unit 42, the gas supply units 3a, 3b, and the like based on the process recipe stored in the control unit 5.

  Thereafter, as shown in FIG. 4C, a polysilicon film 106a to be a control gate 106 is formed on the alumina film 105a on the wafer W unloaded from the reaction vessel 2. Thereafter, the gate structure of the tunnel oxide film 103 to the control gate 106 is obtained from these laminated structures by photolithography or the like, and signal lines are connected to the electrodes 101 and 102 and the control gate 106 to obtain the structure shown in FIG. A flash memory device 100 having the structure shown is formed.

  The film forming apparatus 1 according to the embodiment described above has the following effects. Since a source gas containing a β-diketone complex of aluminum having a high thermal decomposition temperature is used, the aluminum film 105a is formed at a relatively high temperature of 200 to 1,000 ° C., preferably 600 to 1,000 ° C. can do. As a result, it is possible to form an alumina film 105a containing α-alumina. For example, when the alumina film 105a is used as the blocking insulating film 105 of the MONOS type memory element, silicon under the insulating film 105 is formed. A band gap with respect to the charge trap layer 104 made of a nitride film or the like becomes large, and a high-quality memory element 100 with little leakage current can be obtained.

In the film forming apparatus 1 shown in the embodiment, the case where the film forming process is performed by the ALD process in which the source gas and the oxidizing gas are alternately supplied into the reaction vessel 2 has been described. The alumina film 105a containing α-Al ₂ O ₃ may be formed by a normal CVD (Chemical Vapor Deposition) process that continuously supplies oxidizing gas simultaneously. In addition, the injectors 31 and 34 inserted into the reaction vessel 2 may be shortened so that a rising portion that rises up to the upper end of the wafer boat 25 is not provided.

  Furthermore, the oxidizing gas such as oxygen gas supplied to the reaction vessel 2 is supplied to the reaction vessel 2 in an ordinary gas state from an oxidizing gas supply source 37 such as a gas cylinder as shown in the embodiment. It is not limited to the case where it is supplied. For example, as shown in FIG. 5, the plasma generating unit 50 is provided on the side wall of the reaction vessel 2, the second gas injector 34 described above is installed inside the plasma generating unit 50, and the second gas injector 34 is By applying a high frequency voltage to the region where the oxidizing gas is supplied, the oxidizing gas may be supplied into the processing container 2 in a plasma state.

  The configuration of the plasma generation unit 50 will be briefly described. The plasma generation unit 50 is elongated in the vertical direction, and two plasma electrodes 51 (shown in the figure) are provided so as to face each other so as to sandwich the region to which the oxidizing gas is supplied. For convenience, only one is shown in FIG. 5), a partition wall 52 containing the plasma electrode 51, and an insulating protective cover 53 covering the outside of the partition wall 52. A high frequency voltage is applied between the two plasma electrodes from a provided high frequency power source (not shown). The inside of the plasma generation unit 50 and the reaction vessel 2 are communicated with each other through an opening 54 so that the oxidizing gas that has been converted into plasma from the second gas injector 34 can be supplied into the reaction vessel 2. .

In the embodiment described above, the method of forming the alumina film 105a containing α-Al ₂ O ₃ without performing the annealing process has been described, but this is performed after the film formation of the alumina film 105a. It does not exclude that. For example, for the purpose of changing the crystal structure of the alumina film 105a, etc., the film formation of the present invention is also performed in the case where an annealing process is performed at a temperature of, for example, 1,000 ° C. or less after the alumina film 105a is formed. Applicable to the method.

It is sectional drawing which shows the structure of the MONOS type | mold memory element in which the alumina film | membrane of this invention is used. It is a longitudinal cross-sectional view which shows the film-forming apparatus which enforces the film-forming method of this invention. It is a sequence diagram which shows the effect | action of the said film-forming apparatus. FIG. 6 is a longitudinal sectional view showing a manufacturing process of the MONOS type memory device. It is a longitudinal cross-sectional view which shows the modification of the said film-forming apparatus.

Explanation of symbols

MFC1 to MFC3
Mass flow controller W Wafer 1 Film forming apparatus 2 Reaction vessel 3a Raw material gas supply means 3b Oxidation gas supply means 4 Exhaust port 5 Control part 21 Opening part 22 Flange 23 Lid 24 Rotating shaft 25 Wafer boat 26 Strut 27 Thermal insulation unit 31 First Gas injector 32 Raw material gas supply path 33 Raw material source supply source 34 Second gas injector 35 Oxidation gas supply path 37 Oxidation gas supply source 41 Vacuum pump 42 Pressure adjusting means 43 Exhaust pipe 44 Heater 45 Heating furnace 100 Memory element 101 Source electrode 102 Drain electrode 103 Tunnel oxide film 103a Silicon oxide film 104 Charge trap layer 104a Silicon nitride film 105 Blocking insulating film 105a Alumina film 106 Control gate 106a Polysilicon film 110 Silicon substrate 331 Vaporizer 332 Carrier Gas supply source

Claims (8)

Placing the object to be processed in the processing container;
Introducing a source gas containing a β-diketone complex of aluminum into the processing vessel;
Introducing an oxidizing gas into the processing vessel;
By heating the treatment atmosphere in the treatment vessel at a temperature range of 200 ° C. or more and 1,000 ° C. or less, the β-diketone complex and the oxidizing gas are reacted to form α-alumina on the surface of the object to be treated. And a step of forming an alumina film.   2. The method for forming an alumina film according to claim 1, wherein the step of introducing the source gas into the processing container and the step of introducing the oxidizing gas into the processing container are alternately performed.   The source gases are tris (dipivaloylmethanato) aluminum, tris (2,2,6,6-tetramethyl-3,5-octanedionato) aluminum, tris (isobutyrylpivaloylmethanato) aluminum, tris It contains at least one β-diketone complex selected from the group consisting of (diisobutyrylmethanato) aluminum, tris (acetylacetonato) aluminum, and tris (hexafluoroacetylacetonato) aluminum. Item 3. The method for forming an alumina film according to Item 1 or 2.   The said oxidizing gas is selected from the oxidizing gas group which consists of oxygen gas, ozone gas, water vapor | steam, nitrous oxide gas, nitric oxide gas, and nitrogen dioxide gas, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. A method for forming an alumina film. 5. The step of forming the alumina film is performed in a pressure atmosphere within a range of 1.33 Pa to 1.01 × 10 ⁵ Pa. ^5. A method for forming an alumina film.   6. The method for forming an alumina film according to claim 1, wherein the alumina film is a blocking insulating film formed in a MONOS type memory element. A processing container in which an object to be processed is placed;
Heating means for heating the object to be processed;
Raw material gas supply means for supplying a raw material gas containing a β-diketone complex of aluminum into the processing vessel;
Oxidizing gas supply means for supplying oxidizing gas into the processing vessel;
The object to be processed in the processing vessel is heated to a temperature range of 200 ° C. or more and 1,000 ° C. or less, and an alumina film containing α-alumina is formed on the object to be processed using the source gas and the oxidizing gas. And a control means for controlling each means so as to form a film. A storage medium used for an alumina film forming apparatus and storing a program operating on a computer,
A storage medium, wherein the program has steps for executing the film forming method according to any one of claims 1 to 6.

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