JP2000208504A - Method of forming silica film and manufacturing electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a highly reliable insulating film by supplying tetraethoxysilane(TEOS) having high purity and little impurities. SOLUTION: A method of forming a silica film includes the steps of introducing TEOS into an evaporation chamber 4 from a TEOS supply unit 18, introducing a carrier gas into the evaporation chamber 4, introducing a mixed gas of the TEOS and the carrier gas into a reaction chamber 5, introducing an oxidizing gas into the reaction chamber 5 from an oxidizing gas supply unit, heating a substrate in the reaction chamber to a desired temperature to form a silica film on the substrate, and discharging an exhaust gas from the reaction chamber. In this case, the TEOS supply unit 18 is provided with at least one optical liquid level sensor as a device for monitoring the amount of the TEOS.

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 for forming a silica film by a VD) method and a method for manufacturing an electronic component using the same.

[0002]

2. Description of the Related Art Conventionally, when a silica film is formed as an insulating protective film for a semiconductor device or the like in an electronic component, a chemical vapor deposition (CVD) method is used, and monosilane (SiH ₄ ) is used as a raw material. I have been. However, as the degree of integration of the device increases, the aspect ratio of the wiring increases, and the step coverage (step coverage) of the upper insulating film deteriorates, resulting in the generation of voids between the wirings.

In response to these problems, a CVD method using ozone or the like as an oxidizing agent and using tetraethoxysilane [TEOS: Si (OC ₂ H ₅ ) ₄ ] as an organic silicon compound as a raw material has been widely adopted. Has been reached.

A silica film doped with phosphorus atoms or boron atoms is indispensable for an LSI manufacturing process.
It is used as a surface stabilizing film, an interlayer insulating film, an Al wiring protective film, and the like. Even in such a silica film doped with phosphorus or boron, the wiring aspect ratio increases as wiring of semiconductor devices and the like becomes finer and more highly integrated, and the step coverage (step coverage) of the insulating film layer deteriorates. As a result, voids were generated between the wirings. In view of these problems, a CVD method using ozone or the like as an oxidizing agent and using TEOS as a Si source has been widely adopted.

[0005]

However, in semiconductor devices, multi-layer wiring has been developed along with further miniaturization. For example, for an insulating film, a more reliable insulating film is required. Is required to supply TEOS with higher purity and less impurities.

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

[0007]

That is, the present invention provides a step of filling tetraethoxysilane into a vaporization chamber from a tetraethoxysilane supply device; introducing a carrier gas into the vaporization chamber;
A step of introducing a carrier gas / tetraethoxysilane mixed gas into the reactor from a vaporization chamber; a step of introducing an oxidizing gas into the reactor from an oxidizing gas supply device; heating the silica film-forming substrate in the reactor to a desired temperature Forming a silica film on a silica film-forming substrate by exhausting exhaust gas from a reactor, wherein the tetraethoxysilane supply device is used as a tetraethoxysilane liquid amount monitoring means. The present invention relates to a method for forming a silica film, comprising at least one optical liquid level sensor.

Further, the present invention relates to the formation of a silica film in the production of an electronic component comprising the silica film as a constituent element.
The present invention relates to a method for manufacturing an electronic component, which employs the method for forming a silica film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for forming a silica film of the present invention comprises:
Although a conventional CDV device is used, as a TEOS supply device for supplying TEOS to the CDV device,
It is characterized in that a TEOS liquid level monitoring means provided with at least one optical liquid level sensor is used. More specifically, the TEOS supply device comprises 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 TEOS inlet for injecting TEOS into the container body;
It has a TEOS supply port for taking out the OS, and at least one optical liquid level sensor.

First, the TEOS supply device will be described in detail. The TEOS supply device used in the present invention is characterized in that it comprises a stainless steel container main body whose inner surface is electrolytically polished, and a lid that can be joined to the container main body.
An optical liquid level sensor is used to detect the remaining amount of TEOS in the container body of the EOS supply device.

The optical liquid level sensor usable in the TEOS supply device is provided with a light emitting optical fiber and a light receiving optical fiber, and the light emitted from the light emitting 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 TEOS or is immersed only to a certain level, the light emitted from the light projecting optical fiber (26) is converted into the right-angle prism (28). ), Is reflected by the internal reflection surface, is incident on the optical fiber for light reception (27), and is incident on the right-angle prism (2).
The structure is such that light is not scattered to the outside via 8), 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 TEOS at a certain level or more, most of the light emitted from the light-projecting optical fiber (26) is substantially perpendicular to the 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 TEOS via the right-angle prism (28) and is scattered. Accordingly, the incident light that enters 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 increases, and the liquid surface of TEOS becomes higher. It is configured to detect that the right angle prism (28) 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 TEOS 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 TEOS. 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 light emitting optical fiber (26) and the light receiving optical fiber (27) are configured such that the distal ends thereof are widened toward each other toward the front. ), A certain angle is provided between the light emitting axis and the light incident axis of the light receiving optical fiber (27). 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 TEOS liquid level is above a certain level of the conical prism (30).

An optical liquid level sensor provided with a light detecting 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 end. 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. Therefore, by installing the optical liquid level sensor having the above-described configuration at at least one position in the container body of the TEOS supply device and monitoring the remaining amount of TEOS, TEOS is supplied without contamination. be able to.

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 such that their light detecting probes have a step, and
Before the remaining amount of EOS reaches the TEOS liquid level detection position of the lower light detection probe, a warning or the like may be issued at the TEOS liquid level detection position of the other light detection probe provided thereabove. .

By using the TEOS supply apparatus having the above-described structure, a high-purity TEOS raw material having extremely few impurities can be used in the method for forming a silica film of the present invention. In addition, TOS of the TEOS supply device
Since the remaining amount of EOS can be managed with high accuracy, TE
TEOS of the OS supply device can be used efficiently,
When the TEOS remaining amount of the TEOS supply device is low,
The replacement work for the next TEOS supply device can be performed extremely smoothly.

Next, in the method for forming a silica film according to the present invention, TEOS is charged into the TEOS vaporization chamber from the TEOS supply device. TEO filled in TEOS vaporization chamber
S is kept at a constant temperature in order to secure a constant vapor pressure. Here, TEOS is preferably 45 ° C to 70 ° C,
More preferably, the temperature is set to 50 ° C to 65 ° C. Here, a carrier gas (for example, N ₂ , Ar
By introducing an inert gas (e.g., inert gas), a carrier gas / TEOS mixed gas is generated, and the mixed gas is further introduced into the reactor. By adjusting the temperature of TEOS, the TEOS concentration can be controlled, and by adjusting the carrier gas, the ratio of TEOS to the doping material (phosphorus compound or boron compound) described below can be controlled.

In the method for forming a silica film of the present invention,
An oxidizing gas is introduced into the reactor in parallel with the introduction of the TEOS-containing gas into the reactor. Preferred examples of the oxidizing gas include an ozone-containing gas. As the oxidizing gas supply device, for example, in the case of such an ozone-containing gas, a device for supplying an ozone-containing gas by passing O ₂ gas through an ozonizer can be used. Ozone-containing gas as the oxidant gas, for example O ₂ with respect to 1.5 to 7%, it is good preferably ozone concentration of 3-6%.

Further, in the method for forming a silica film according to the present invention,
And a diluting gas (eg, N _TwoInactive, such as Ar
Gas) can be introduced. Introduce dilution gas
This makes it possible to adjust the concentration of the entire raw material gas.
In this case, the film forming property and the film forming rate can be controlled. In addition,
The dilution gas may be introduced directly into the reaction chamber,
It may be mixed with the source gas.

The silica film is formed (deposited) on the substrate by heating the substrate on which the silica film is formed to a desired temperature while the above-mentioned gas is introduced into the reaction chamber. The substrate temperature at this time is preferably 300 ° C. to 500 ° C., and more preferably 350 ° C. to 450 ° C. The film thickness can be arbitrarily controlled by increasing or decreasing the film growth time (silica deposition time).

Further, the method for forming a silica film of the present invention can be used even when the silica film is a silica film doped with phosphorus. To dope phosphorus, a phosphorus compound gas may be further introduced into the reactor. As the phosphorus compound gas, any known gas for phosphorus doping can be used. For example, phosphine, trimethyl phosphate (TMOP), trimethyl phosphite (TM
P), triethyl phosphate (TEOP) and the like can be used, but are not limited thereto.

If the phosphorus compound to be used is a gas at room temperature, it is kept as it is. If the phosphorus compound is a liquid or a solution at room temperature, the temperature is maintained at a vapor pressure such that a desired phosphorus content is obtained. It can be used by introducing. As the carrier gas and the diluent gas, those similar to the above can be used.
It can be used as above.

Further, the method for forming a silica film of the present invention can be used even when the silica film is a silica film doped with boron. To dope boron, a boron compound gas may be further introduced into the reactor. As the boron compound gas, any known gas for boron doping can be used. For example, trimethyl borate (TMB), triethyl borate (TEB) and the like can be used, but are not limited thereto.

If the boron compound used is a gas at room temperature, if the boron compound is a liquid or a solution at room temperature, it is kept at a temperature at which the boron pressure becomes a vapor pressure so as to obtain a desired boron content. It can be used by introducing. The carrier gas and the diluting gas may be the same as those described above, and the oxidizing gas may be the same as the above, and the same as the above.

[0028]

[Examples] Next, examples will be shown to specifically explain the method for forming a silica 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 silica film of the present invention. In FIG.
Reactor (chamber) for forming silica film (5)
Is composed of a dispersion head (6), a heater (7), a Si wafer substrate (8) as a substrate on which a silica film is formed, and an exhaust port (9). Further, the ozone-containing gas used for the reaction in the reactor (5) is supplied to a flow meter (1a),
Valve (2a), Ozonizer (3), Valve (2d)
Through the reactor (5). Further, the diluting gas can be supplied via a flow meter (1b) and a valve (2b). The carrier gas is supplied from a flow meter (1c) and a valve (2c).
And supply to the TEOS vaporization chamber (4) via the

Next, the TEOS supply device (18) shown in FIG. 1 will be described in detail with reference to FIG. TEO shown in FIG.
The S supply device (18) includes a TEOS supply device container body (10) made of stainless steel whose inner surface is electrolytically polished, and a lid (20) that can be joined to the TEOS supply device container body (10). Have been. Here, the TEOS supply device container main body (10) and the lid part (20) are, for example, airtightly joined to each other by a joining means such as a bolt and a nut (19). The lid (20) has a TEOS inlet (12) for injecting TEOS into the TEOS supply device container main body (10) and a TEOS for removing TEOS from the TEOS supply device container main body (10).
An OS supply port (11) and an optical liquid level sensor (13) are provided. In addition, the TEOS injection port (12)
A valve (2 g) for controlling the injection of TEOS
The EOS supply port (11) is provided with a valve (2f) for controlling the supply of TEOS. The light detection probe (14) at the tip of the optical liquid level sensor (13) is installed at a predetermined position around the bottom of the TEOS supply device main body (10). Further, the optical liquid level sensor (13) includes a light emitter / receiver (15) and a detection circuit (1).
6) is connected to detect the remaining amount of TEOS based on the signal output from the detection circuit (16) and stop the supply of TEOS or stop the operation of the CVD apparatus when the remaining amount becomes equal to or less than a predetermined amount. Various controls can be performed.

First, a high-purity TEOS material is supplied to a valve (2).
g) by operating the TEOS through the TEOS inlet (12).
The OS supply device container body (10) was filled. Next, TE
TEOS was charged into the TEOS vaporization chamber (4) from the OS supply device container body (10) through the TEOS supply port (11) by operating the valve (2f). At this time, TE
The end point of the TEOS supply was monitored using an optical liquid level sensor (13) having a light detection probe (14) installed in the OS supply device container body (10).

TEOS filled in TEOS vaporization chamber (4)
Is kept at 60 ° C. to keep the vapor pressure constant, and the Si wafer substrate (8) in the reaction chamber (5) is heated to 40 ° C. by the heater (7).
Heated to 0 ° C. Next, N ₂ is used as a carrier gas with TE.
A gas containing TEOS was introduced into the reactor (5) by blowing into the OS vaporization chamber (4) at 3 L / min. At the same time, N ₂ was introduced as a dilution gas at a rate of 18 liters / minute, and O ₂ gas was passed through an ozonizer (3) to reduce the ozone concentration to O _2.
And a 1.2 μm silica (SiO ₂ ) film was obtained on the Si wafer substrate (8).

The amount of impurities in the high-purity TEOS filled in the TEOS vaporization chamber from the TEOS supply device when the same operation was performed was measured by measuring the number of particles of 0.2 μm or more. The result was 15.7 (pieces / milliliter). In addition, the dielectric constant of the obtained silica film was measured in order to examine the insulating property. The measured value was 4.3, which was suitable for the production of a large-capacity (64 MB) semiconductor memory. Was good.

[Embodiment 2] FIG. 5 shows the C used in this embodiment.
FIG. 2 is a schematic structural diagram of a VD device. That is, the CV shown in FIG.
The apparatus D is provided with means for introducing trimethyl phosphate (TMOP), which is a phosphorus raw material compound, into the reactor (5) in order to dope the silica film with phosphorus. The TMOP vaporized by the vaporizer (17) is supplied to the flow meter (1).
e), the carrier gas introduced through the valve (2j) is introduced into the reactor (5) through the valve (2k).

First, a high-purity TEOS as a raw material is supplied to a valve (2).
g) by operating the TEOS through the TEOS inlet (12).
The OS supply device container body (10) was filled. Next, TE
TEOS was charged into the TEOS vaporization chamber (4) from the OS supply device container body (10) through the TEOS supply port (11) by operating the valve (2f). At this time, TE
The end point of the TEOS supply was monitored using an optical liquid level sensor (13) having a light detection probe (14) installed in the OS supply device container body (10).

TEOS filled in TEOS vaporization chamber (4)
At 65 ° C. and TMOP in the vaporization chamber (17) at 60 ° C. to keep the vapor pressure constant, and the Si wafer substrate (8) in the reaction chamber (5) is heated at 40 ° C. by the heater (7).
Heated to 0 ° C. Next, N ₂ is used as a carrier gas with TE.
A gas containing TEOS was introduced into the reactor (5) by blowing into the OS vaporization chamber (4) at 3 L / min. Further, N ₂ as a carrier gas was blown into the vaporization chamber (17) at a rate of 1.5 liter / minute, and a gas containing TMOP was introduced into the reactor (5). At the same time, N ₂ was introduced as a dilution gas at a rate of 18 liters / minute, and O ₂ gas was further introduced into an ozonizer (3).
And the ozone concentration is set to 5% with respect to O ₂ and introduced, so that 1.2 μm on the Si wafer substrate (8).
Was obtained.

The amount of impurities in the high-purity TEOS charged into the TEOS vaporization chamber from the TEOS supply device when the same operation was performed was measured by measuring the number of particles having a size of 0.2 μm or more. The result was 16.2 (pieces / milliliter). In addition, the dielectric constant of the obtained phosphorus-doped silica film was measured in order to examine the insulating property.
4, which is suitable for manufacturing a large-capacity (64 MB) semiconductor memory, and a large-capacity semiconductor memory manufactured therefrom was excellent.

[Embodiment 3] FIG. 5 shows the C used in this embodiment.
FIG. 2 is a schematic structural diagram of a VD device. That is, the CV shown in FIG.
In the D apparatus, in order to dope the silica film with boron, boron-containing compound triethyl borate (TE) is used.
A means for introducing B) into the reactor (5) is provided. The TEB vaporized by the vaporizer (17) is configured to be introduced into the reactor (5) through the valve (2k) by the carrier gas introduced through the flow meter (1e) and the valve (2j). I have.

First, a high-purity TEOS raw material is supplied to a valve (2).
g) by operating the TEOS through the TEOS inlet (12).
The OS supply device container body (10) was filled. Next, TE
TEOS was charged into the TEOS vaporization chamber (4) from the OS supply device container body (10) through the TEOS supply port (11) by operating the valve (2f). At this time, TE
The end point of the TEOS supply was monitored using an optical liquid level sensor (13) having a light detection probe (14) installed in the OS supply device container body (10).

TEOS filled in TEOS vaporization chamber (4)
At 65 ° C. and TEB in the vaporization chamber (17) at 15 ° C. to keep the vapor pressure constant, and the reaction chamber (5)
The Si wafer substrate (8) inside was heated to 400 ° C. by the heater (7). Next, N ₂ as a carrier gas was blown into the TEOS vaporization chamber (4) at a rate of 3 liters / minute, and the reactor (5)
A gas containing TEOS was introduced therein. Further, N ₂ as a carrier gas was blown into the vaporization chamber (17) at a rate of 1.5 liter / minute, and a gas containing TEB was introduced into the reactor (5). At the same time, N ₂ was introduced at 18 liters / minute as a diluting gas, and O ₂ gas was passed through an ozonizer (3).
By introducing an ozone concentration of 5% with respect to O ₂ , a boron-doped silica film of 1.2 μm was obtained on the Si wafer substrate (8).

The amount of impurities in the high-purity TEOS filled in the TEOS vaporization chamber from the TEOS supply device when the same operation was performed was measured by measuring the number of particles of 0.2 μm or more. The result was 15.1 (pieces / milliliter). Also, when the dielectric constant was measured to examine the insulating property of the obtained boron-doped silica film,
4.3, which is suitable for manufacturing a large-capacity (64 MB) semiconductor memory, and a large-capacity semiconductor memory manufactured therefrom was excellent.

[Comparative Example] In the same manner as in Example 1, except that
TEO having a float type liquid level sensor conventionally used instead of an optical liquid level sensor as a TEOS supply device
A 1.0 μm boron-doped silica film was formed using an S supply device. TE when performing the same operation
High purity T filled into TEOS vaporization chamber from OS supply device
The amount of impurities in EOS was measured by measuring the number of particles of 0.2 μm or more. The result was 962 (pieces /
Milliliters). In addition, the dielectric constant of the obtained boron-doped silica film was measured to be 5.5, which was 5.5, which was not practical for the production of a large-capacity (64 MB) semiconductor memory. The large-capacity semiconductor memory was defective.

[0042]

According to the method for forming a silica film of the present invention, the use of a TEOS supply device having an optical liquid level sensor makes it possible to use a high-purity TE with very few impurities.
OS materials can be used, and the dielectric constant is extremely low.
A silica 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 Embodiment 1 of the present invention.

FIG. 2 is a schematic view of a TEOS supply device used in an embodiment.

FIG. 3 is a diagram showing a configuration of a light detection probe of an optical liquid level sensor of a TEOS supply device used in the method for forming a boron-doped silica film of the present invention.

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

FIG. 5 is a schematic structural view of a CVD apparatus used in Examples 2 and 3 of the present invention.

[Explanation of symbols]

 1a-1d: Flow meter 2a-2i: Valve 3: Ozonizer 4: TEOS vaporization chamber 5: Reactor (chamber) 6: Dispersion head 7: Heater 8: Si wafer substrate 9: Exhaust port 10: TEOS supply device Container body 11: TEOS supply port 12: TEOS injection port 13: Optical liquid level sensor 14: Optical detection probe 15: Light emitting and receiving device 16: Detection circuit 17: Vaporization chamber 18: TEOS supply device 19: Bolt and nut 20: Lid Part 26: Optical fiber for light projection 27: Optical fiber for light reception 28: Right angle prism 29: Protection 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

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Continued on front page F-term (reference) 2F014 AB02 AB03 FA02 4K030 AA06 AA14 AA20 BA26 BA44 CA04 CA12 EA01 JA06 KA39 LA02 5F045 AB32 AB36 AC08 AC09 AC11 AC15 AC19 AD08 BB15 BB19 CB05 DC63 DP03 EE03 EE04 EE05 5BF0BF29 BF05 BF33 BG02 BG10 BJ02

Claims (9)

[Claims] 1. a step of filling tetraethoxysilane into a vaporization chamber from a tetraethoxysilane supply device; a step of introducing a carrier gas into the vaporization chamber; and a step of introducing a carrier gas / tetraethoxysilane mixed gas from the vaporization chamber into a reactor; Introducing the oxidizing gas from the oxidizing gas supply device into the reactor; heating the silica film-forming substrate in the reactor to a desired temperature to form a silica film on the silica film-forming substrate; In a method for forming a silica film having a step of discharging exhaust gas, a tetraethoxysilane supply device includes at least one tetraethoxysilane liquid amount monitoring means.
A method for forming a silica film, comprising: two optical liquid level sensors. 2. The method according to claim 1, further comprising the step of introducing a diluting gas into the reaction chamber to adjust the concentration of the raw material gas.
The method for forming a silica film according to the above. 3. The method according to claim 1, wherein the silica film is a phosphorus-doped silica film and further has a phosphorus compound gas introduction step.
The method for forming a silica film according to claim 1. 4. The method for forming a silica film according to claim 1, wherein the silica film is a boron-doped silica film and further has a boron compound gas introduction step. 5. A tetraethoxysilane supply device comprising a stainless steel container body having an inner surface electrolytically polished and a lid capable of being joined to the container body, wherein the container body and / or A lid, a tetraethoxysilane injection port for injecting tetraethoxysilane into the container main body, a tetraethoxysilane supply port for removing tetraethoxysilane from the container main body, and at least one optical liquid level sensor The method for forming a silica film according to any one of claims 1 to 4, wherein the method comprises: 6. An optical liquid level sensor comprising a light projecting optical fiber and a light receiving optical fiber juxtaposed, and a plurality of optical liquid level sensors for causing light emitted from the light projecting optical fiber to enter the light receiving optical fiber in front of the distal ends of the two optical fibers. 6. The method for forming a silica film according to claim 5, wherein a light detection probe provided with a prism portion having an internal reflection surface is used. 7. The method for forming a silica film according to claim 6, wherein the leading ends of the light projecting optical fiber and the light receiving optical fiber in the light detection probe are widened forward. 8. The method for forming a silica film according to claim 5, wherein the internal electrolytic polishing stainless steel container is provided with a lid having a wide opening to the extent that the internal cleaning is possible. 9. A method for forming a silica film according to any one of claims 1 to 8, wherein the silica film is formed in the manufacture of an electronic component having the silica film as a constituent element. Manufacturing method of electronic components.