JP2000212750A - Method for forming tantalum oxide film and production of electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a tantalum oxide film capable of obtaining an insulating film or the like high in reliability by feeding PET having high purity and small in impurities and to provide a method for producing electronic parts using it. SOLUTION: This method for forming a tantalum oxide film contains a stage in which pentaethoxytantalum is filled into a vaporizing chamber 2 from a pentaethoxytantalum feeding device, a stage in which carrier gas 1 is introduced into the vaporizing chamber, and a gaseous mixture of carrier gas- pentaethoxytantalum is introduced from the vaporizing chamber into a reactor 4, a stage in which oxidizer gas 3 is introduced into the reactor, a stage in which a substrate to be formed with tantalum oxide 5 in the reactor is heated to desired temp. to form a tantalum oxide film on the substrate to be formed with tantalum oxide and a stage in which exhaust gas is exhausted from the reactor. In this case, the pentaethoxytantalum feeding device 18 is provided with at least one optical liq. face sensor as a liq. amt. monitoring means for pentaethoxytantalum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chemical vapor deposition (C) process.
The present invention relates to a method of forming a tantalum oxide film by a VD) method and a method of manufacturing an electronic component using the same.

[0002]

2. Description of the Related Art Indispensable for semiconductor devices in electronic parts.
As an edge protection film, it can be used for large capacity memory, etc.
Introduction of tantalum oxide film, a high dielectric constant film,
Have been. To form such a tantalum oxide film,
In addition to the conventional sputtering method, JP-A-61-190074
In Japanese Unexamined Patent Publication No. 4-115533, a sputtering method is used.
Ta (OC) which causes less damage to the substrate due to the generated charged particles
H_Three)_Five, Ta (OC_TwoH_Five) _FiveSuch as Ta alkoxide
The chemical vapor deposition (CVD) method used was examined and used.
At present, suitable for film formation by CVD film formation method
Chemical properties (vapor pressure, melting point, etc.)
Ta (OC_TwoH_Five)_Five(Pentaethoxy tanta
Of Ta alkoxide mainly composed of PET)
Is being used.

However, as the degree of integration of devices has increased, the performance of the insulating film has been reduced due to the presence of slight impurities.

[0004]

Semiconductor devices are being miniaturized further. For example, for an insulating film, a more reliable insulating film is required. Therefore, there is a demand for the supply of PET with less impurities.

Accordingly, an object of the present invention is to provide a method for forming a tantalum oxide film capable of obtaining a highly reliable insulating film or the like by supplying PET with high purity and few impurities in order to solve the above problems. And a method of manufacturing an electronic component using the same.

[0006]

That is, the present invention relates to PET
Filling PET into the vaporization chamber from the supply device; introducing a carrier gas into the vaporization chamber;
Introducing a T-mixed gas into the reactor; introducing an oxidizing gas into the reactor; heating the substrate on which the tantalum oxide film is formed in the reactor to a desired temperature to form a tantalum oxide film on the tantalum oxide film-formed substrate Forming a tantalum oxide film having a step of discharging exhaust gas from a reactor, wherein the PET supply device comprises at least one optical liquid level sensor as a PET liquid amount monitoring means. The present invention relates to a characteristic method for forming a tantalum oxide film.

Further, according to the present invention, in the production of an electronic component having a tantalum oxide film as a constituent element, the method for producing an electronic component is characterized by employing the above-described method of forming a tantalum oxide film when forming the tantalum oxide film. According to.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for forming a tantalum oxide film of the present invention uses a conventional CDV apparatus.
It is characterized in that a PET supply device for supplying PET to the V apparatus is provided with at least one optical liquid level sensor as PET liquid amount monitoring means. More specifically, the PET supply device includes a container body made of stainless steel whose inner surface is electrolytically polished and a lid that can be joined to the container body, and the container body and / or the lid are formed. A PET injection port for injecting PET into the container body, a PET supply port for removing PET from the container body, and at least one optical liquid level sensor. .

First, the PET supply device will be described in detail.
The feature of the PET supply device used in the present invention is that the inside of the container body portion of the PET supply device is composed of a stainless steel container main body whose inner surface is electrolytically polished and a lid that can be joined to the container main body. In order to detect the remaining amount of PET, an optical liquid level sensor is used.

An optical liquid level sensor usable in a PET supply device is provided with a light projecting optical fiber and a light receiving optical fiber, and the light emitted from the light projecting optical fiber is forwardly transmitted to the light receiving optical fiber in front of the ends of both optical fibers. In this case, a light detection probe provided with a prism portion having a plurality of internal reflection surfaces for incidence is used.

FIG. 3 shows a light detection probe of this optical liquid level sensor. In FIG. 3, a right-angle prism (28) having an internal reflection surface is provided at the distal end of the optical fiber for light emission (26) and the optical fiber for light reception (27) installed in parallel. Further, a protection tube (29) for protecting the light emitting optical fiber (26) and the light receiving optical fiber (27) is integrally formed with the right-angle prism (28), and can be made of fluororesin or the like.

An optical liquid level sensor provided with such a light detection probe operates as follows. First, when the right-angle prism (28) of the light detection probe is not immersed in the PET or is immersed only to a certain level, the light emitted from the light emitting optical fiber (26) is converted into the right-angle prism (28). ) Is reflected by the internal reflection surface, enters the light receiving optical fiber (27), and is incident on the right-angle prism (28).
The structure is such that light is not scattered to the outside through the interface, and the difference between the intensity of the emitted light and the intensity of the incident light is small when the intensity of the emitted light and the intensity of the incident light are measured.

On the other hand, when the right-angle prism (28) is immersed in the PET at a certain level or higher, most of the light emitted from the light-projecting optical fiber (26) is almost right-angle prism (28). Therefore, almost no incident light is transmitted through the internal reflection surface of the right-angle prism (28) and reflected by the internal reflection surface of the right-angle prism (28) to enter the optical fiber for light reception (27). In this case, the emitted light travels through the PET via the right-angle prism (28) and is scattered. Therefore, the incident light incident through the right-angle prism (28) is very weak, and when the intensity of the outgoing light and the incident light is detected, the difference between the intensity of the outgoing light and the incident light becomes large, and the liquid level of the PET becomes higher. Right angle prism (2
8) It is possible to detect that it is above a certain level.

By the way, when an optical liquid level sensor having a light detecting probe having the structure shown in FIG. 3 is installed near the bottom of the container body, the right angle prism (2
8) The outgoing light that passes through the PET after passing through 8) may be reflected on the bottom of the container body and become incident light via the right-angle prism (28). In such a case, the difference between the intensity of the emitted light and the intensity of the incident light becomes small, and it may be difficult to detect the liquid level of the PET. In such a case, the difference between the emitted light and the incident light can be increased by using a light detection probe having a configuration as shown in FIG. That is, as shown in FIG. 4, the leading ends of the light emitting optical fiber (26) and the light receiving optical fiber (27) are
By diverging forward, the light emitting axis of the light projecting optical fiber (26) and the light incident axis of the light receiving optical fiber (27) have a certain angle. When the light detection probe having such a configuration is installed near the bottom of the container body, even if the outgoing light transmitted through the conical prism (30) is reflected on the bottom surface, the incident light from the conical prism (30) is used. Can be prevented, so that the intensity of the incident light can be made weaker, and thus the difference between the intensity of the emitted light and the intensity of the incident light when the intensity of the emitted light and the intensity of the incident light are detected. Can be made larger. That is, it is possible to more clearly determine that the PET liquid level is above a certain level of the conical prism (30).

An optical liquid level sensor provided with a light detection probe as shown in FIGS. 3 and 4 is a light emitting optical fiber (for example, made of fluororesin) integrally formed with a prism at the tip. 26) and the optical fiber for light reception (27) are accommodated, and the optical liquid level sensor having such a configuration has no mechanical contact between the constituent members, and thus generates new particles. There is no. Accordingly, by monitoring the remaining amount of PET by installing the optical liquid level sensor having the above-described configuration at at least one position in the container body of the PET supply device,
ET can be supplied without contaminating it.

Further, in order to accurately install the light detecting probe portion of the optical liquid level sensor at a predetermined position near the bottom of the container body, a light transmitting optical fiber (26) and a light receiving light are placed in a protective tube (29). It is also possible to adopt a configuration in which a support rod (for example, a metal rod) is inserted together with the optical fiber (27) for use to maintain the shape of the optical liquid level sensor.

Further, two or more optical liquid level sensors are installed so that their light detecting probes have a step, and
Before the remaining amount of the ET reaches the PET liquid level detection position of the lower light detection probe, a warning may be issued at the PET liquid level detection position of the other light detection probe provided thereabove. .

By using the PET supply device having the above-described configuration, in the method for forming a tantalum oxide film of the present invention, a high-purity PET raw material having extremely few impurities can be used. In addition, P of the PET supply device
Since the remaining amount of ET can be managed accurately, PET
The PET of the feeder can be used efficiently and the PET
When the remaining amount of PET in the supply device is low, the next PET
The replacement work or the like with the supply device can be performed extremely smoothly.

In the method for forming a tantalum oxide film according to the present invention, PET is filled into the PET vaporization chamber from the above PET supply device. The PET filled in the PET vaporization chamber is kept at a constant temperature in order to secure a constant vapor pressure. Here, the PET is preferably set to 120 ° C. to 180 ° C., more preferably 135 ° C. to 170 ° C. here,
By introducing a carrier gas (for example, an inert gas such as N ₂ or Ar) into the PET vaporization chamber, the carrier gas / PE is introduced.
A T-mixed gas is generated and further introduced into the reactor. The concentration of PET in the carrier gas / PET mixed gas can be controlled by adjusting the temperature of PET.

In the method of forming a tantalum oxide film according to the present invention, an oxidizing gas is introduced into the reactor in parallel with the introduction of the PET-containing gas into the reactor. As the oxidizing gas,
O ₂ can be used containing gas can also be used air.

By heating the substrate on which the tantalum oxide film is formed to a desired temperature in a state where the above-mentioned gas is introduced into the reaction chamber, a tantalum oxide film is formed (deposited) on the substrate. The substrate temperature at this time is preferably 350 ° C to 600 ° C,
More preferably, the temperature is from 400 ° C to 500 ° C.
The film thickness can be arbitrarily controlled by increasing or decreasing the film growth time (silica deposition time).

[0022]

EXAMPLES Next, examples are shown to specifically explain the method for forming a tantalum oxide film of the present invention. Embodiment 1 FIG. 1 is a schematic structural view of a CVD apparatus used in the method for forming a tantalum oxide film of the present invention. In FIG. 1, a carrier (PET) mixed gas and an oxidizing gas (3) from a PET vaporization chamber (2) are introduced into a reactor (chamber) (4) for forming a tantalum oxide film. I have. Further, a heating means (7) is provided in the reactor (4), so that the inside of the reactor (4) can be heated and kept at a set temperature. Further, a Si wafer substrate (5) as a substrate on which a tantalum oxide film is formed is provided, and an exhaust port (6) for exhausting the atmosphere in the reactor (4) is provided. The carrier gas (1) and the PET from the PET supply device (18) are supplied to the PET vaporization chamber (2).

Next, the PET supply device (1) shown in FIG.
8) will be described in detail with reference to FIG. The PET supply device (18) shown in FIG. 2 is a stainless steel PET supply device container body (14) made of electrolytically polished inner surface and a lid portion that can be joined to the PET supply device container body (14). (1
6). Here, the PET supply device container main body (14) and the lid (16) are air-tightly joined to each other by means of joining means such as a bolt and a nut (17), for example. The lid (16) has a PE for injecting PET into the PET supply device container body (14).
A T inlet (15), a PET supply port (9) for removing PET from the PET supply device container body (14), and an optical liquid level sensor (11) are provided. In addition, PE
The T inlet (15) is provided with a valve (8b) for controlling the injection of PET, and the PET supply port (9) is provided with a valve (8a) for controlling the supply of PET. . The light detection probe (10) at the tip of the optical liquid level sensor (11) is connected to the PET supply device body (1).
It is installed at a predetermined position around the bottom of 4). Also,
The optical liquid level sensor (11) is connected to the light emitting / receiving device (12) and the detection circuit (13), and the detection circuit (13)
Detection of the remaining amount of PET according to the signal output from
It is configured to perform various controls such as stopping the operation of the device.

First, a high-purity PET material was placed in a valve (8
b) PET through the PET inlet (15) by the operation of b)
The supply device container body (14) was filled. Next, the valve (8a) is operated from the PET supply device container body (14) to the PET vaporization chamber (4) through the PET supply port (9).
ET was charged. At this time, the end point of the PET supply amount was monitored using an optical liquid level sensor (11) having a light detection probe (10) installed in the PET supply device container body (14).

The PET filled in the PET vaporization chamber (4) is
The vapor pressure is kept constant by keeping the temperature at 50 ° C., and the Si wafer substrate (5) in the reaction chamber (4) is heated by the heater (7) to 50 ° C.
Heated to 0 ° C. Next, Ar is used as a carrier gas for PE.
The gas was blown into the T vaporization chamber (4) at a rate of 40 ml / min, and a gas containing PET was introduced into the reactor (4). Further, air is blown into the reactor (4) as the oxidizing gas (3) at a rate of 100 ml / min, and the exhaust gas from the reactor (4) is removed from the exhaust port (6) at a reduced pressure of 5 torr. By the reaction, a tantalum oxide thin film having a thickness of 40 nm was formed on the Si wafer (5).

When the same operation was performed, the amount of impurities in the high-purity PET filled in the PET vaporization chamber from the PET supply apparatus was measured by measuring the number of particles having a particle size of 0.2 μm or more. The result was 15.5 (pieces / milliliter). In addition, the leakage current was measured to check the insulating property of the obtained tantalum oxide film.
It is 2 × 10 ⁻⁹ A / cm ^{2 in} cm, which is suitable for manufacturing a large-capacity (64 MB) semiconductor memory, and a large-capacity semiconductor memory manufactured therefrom was excellent.

Comparative Example As in Example 1, except that
A tantalum oxide film having a thickness of about 40 nm was formed by using a PET supply device having a float type liquid level sensor conventionally used instead of the optical liquid level sensor as the PET supply device. The amount of impurities in the high-purity PET filled in the PET vaporization chamber from the PET supply device when the same operation was performed was measured by measuring the number of particles having a particle size of 0.2 μm or more. The result was 983 (pieces / milliliter). In addition, the leakage current was measured to check the insulating properties of the obtained tantalum oxide film. As a result, the leakage current was 3 × 10 ⁻³ A / cm ² at 1 MV / cm, which is practical for manufacturing a large-capacity (64 MB) semiconductor memory. The large-capacity semiconductor memory manufactured from this was defective.

[0028]

According to the method for forming a tantalum oxide film of the present invention, the use of a PET supply device equipped with an optical liquid level sensor allows the use of a high-purity P with very few impurities.
An ET raw material can be used, and a tantalum oxide film having good insulating properties can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a CVD apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic view of a PET supply device used in an example.

FIG. 3 is a diagram showing a configuration of a light detection probe of an optical liquid level sensor of a PET supply device used in the method for forming a tantalum oxide film of the present invention.

FIG. 4 is a diagram showing another configuration of the light detection probe of the optical liquid level sensor.

[Explanation of symbols]

 1: Carrier gas 2: PET vaporization chamber 3: Oxidizing gas 4: Reactor (chamber) 5: Si wafer substrate 6: Exhaust port 7: Heaters 8a, 8b: Valve 9: PET supply port 10: Light detection probe 11 : Optical liquid level sensor 12: Emitter / receiver 13: Detection circuit 14: PET supply device container body 15: PET inlet 16: Lid 17: Bolt and nut 18: PET supply device 26: Optical fiber for light emission 27: Light reception Optical fiber for use 28: Right angle prism 29: Protective tube 30: Conical prism

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[Procedure amendment]

[Submission date] October 15, 1999 (1999.10.
15)

[Procedure amendment 1]

[Document name to be amended] Drawing

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FIG. 2

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

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[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

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FIG. 4

Continued on front page F term (reference) 4K030 AA11 AA14 AA16 BA17 BA42 CA04 CA12 EA01 HA17 KA39 LA02 LA15 5F045 AB31 AC07 AC11 AC15 AC16 AD07 AD08 AD09 AD10 AF03 BB16 EE02 5F058 BA11 BB04 BC03 BF02 BF27 BF29 BG10 B

Claims (6)

[Claims] 1. a step of filling pentaethoxy tantalum into a vaporization chamber from a pentaethoxy tantalum supply device; a step of introducing a carrier gas into the vaporization chamber and a step of introducing a carrier gas / pentaethoxy tantalum mixed gas from the vaporization chamber into the reactor; Introducing an oxidant gas into the reactor; heating the substrate on which the tantalum oxide film is formed in the reactor to a desired temperature to form a tantalum oxide film on the substrate on which the tantalum oxide film is formed;
A method for forming a tantalum oxide film having a step of discharging exhaust gas from a reactor, wherein the pentaethoxy tantalum supply device is provided with at least one optical liquid level sensor as a pentaethoxy tantalum liquid amount monitoring means. Forming a tantalum oxide film. 2. A pentaethoxy tantalum supply device, comprising: a stainless steel container main body whose inner surface is electrolytically polished; and a lid capable of being joined to the container main body.
The container main body and / or the lid have a pentaethoxy tantalum injection port for injecting pentaethoxy tantalum into the container main body, a pentaethoxy tantalum supply port for removing pentaethoxy tantalum from the container main body, and at least 2. The method for forming a tantalum oxide film according to claim 1, wherein the method comprises one optical liquid level sensor. 3. An optical liquid level sensor comprising a light projecting optical fiber and a light receiving optical fiber juxtaposed, wherein light emitted from the light projecting optical fiber is made to enter the light receiving optical fiber in front of the distal ends of the two optical fibers. 3. The method for forming a tantalum oxide film according to claim 2, wherein a light detection probe provided with a prism portion having an internal reflection surface is used. 4. The method for forming a tantalum oxide film according to claim 3, wherein the tip ends of the light projecting optical fiber and the light receiving optical fiber of the light detection probe are widened forward. 5. The internal electrolytic polishing stainless steel container is provided with a lid having a wide opening to enable internal cleaning.
The method for forming a tantalum oxide film according to any one of the above items. 6. A method of forming a tantalum oxide film according to claim 1, in forming an electronic component having the tantalum oxide film as a constituent element. Characteristic electronic component manufacturing method.