JP2000277516A - Method of forming boron-doped silica film and manufacture of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable insulating film or the like by providing an optical liquid level sensor as a liquid amount monitoring means for triethylborate in a triethylborate supply apparatus. SOLUTION: An optical detector probe 14 at the top of an optical liquid level sensor 13 is arranged at a specified position near the bottom of the body of a TEB(triethylborate) supply apparatus. A light transmitter/receiver 15 and a detector circuit 16 are connected to the optical liquid level sensor 13. The residual amount of TEB is detected by a signal outputted from the detector circuit 16, and when the residual amount is fewer than a specified value, various kinds of control such as TEB supply stoppage or CVD apparatus operation stoppage are conducted. Tetraethoxysilane(TEOS), which is the raw material compound for silicon, is introduced from a TEOS vaporizer to a reaction chamber. As a result, a boron-doped silica film having remarkably low permittivity and excellent insulating capability can be formed.

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

[0002]

2. Description of the Related Art A boron-doped silica film obtained by doping a silica film with boron is indispensable for an LSI manufacturing process.
It is used for a surface stabilizing film, an interlayer insulating film, an Al wiring protective film, and the like. For the formation of such a boron-doped silica film,
Although the chemical vapor deposition (CVD) method is used, the aspect ratio of the wiring increases as the 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, a void was generated between the wirings.

[0003] In response to these problems, the ozone used to oxidizing agent is now, Si source - scan as tetraethoxysilane _{[TEOS: Si (OC 2 H} 5) 4] alkoxysilanes such as triethyl borate as B source [TEB:
B (OC ₂ H ₅ ) ₃ ] has been widely adopted.

[0004]

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. Requires a supply of TEB with higher purity and less impurities.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems by providing a boron-doped silica capable of obtaining a highly reliable insulating film or the like by supplying TEB with high purity and few impurities. An object of the present invention is to provide a method for forming a film and a method for manufacturing an electronic component using the same.

[0006]

That is, the present invention provides a TEB
Filling TEB into the vaporization chamber from the supply device; introducing a carrier gas into the vaporization chamber;
A step of introducing a B-mixed gas into the reactor; a step of introducing an oxidant gas from the oxidant gas supply device into the reactor; a step of introducing an alkoxysilane gas into the reactor; Forming a boron-doped silica film on the substrate on which the boron-doped silica film is formed by heating to a temperature; and discharging the exhaust gas from the reactor.
The supply device has at least one as a means for monitoring the liquid level of TEB.
The present invention relates to a method for forming a boron-doped silica film comprising two optical liquid level sensors.

Further, the present invention provides a method of manufacturing an electronic component, wherein the method of forming a boron-doped silica film is employed in forming the boron-doped silica film in the manufacture of an electronic component having the boron-doped silica film as a constituent element. According to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for forming a boron-doped silica film of the present invention uses a conventional CDV device. As a TEB supply device for supplying TEB to the CDV device, a TEB liquid amount monitoring means is used. Is characterized in that a device having at least one optical liquid level sensor is used. More specifically, the TEB 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,
The container main body and / or the lid are connected to the container main body by TE.
TEB inlet for injecting B, T
TEB inlet for removing EB, and at least one
This is a configuration having two optical liquid level sensors.

First, the TEB supply device will be described in detail.
The feature of the TEB supply device used in the present invention is that the inside of the container body portion of the TEB supply device 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 TEB, an optical liquid level sensor is used.

The optical liquid level sensor usable in the TEB 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 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 TEB 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 TEB at a certain level or more, 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 outgoing light travels through the TEB via the right-angle prism (28) and is scattered. Therefore, 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 becomes large, and the liquid surface of the TEB 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 passing through the TEB 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 TEB liquid level. 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 can be determined more clearly that the liquid level of the TEB 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. Therefore, by installing the optical liquid level sensor having the above-described configuration at at least one position in the container body of the TEB supply device and monitoring the remaining amount of TEB,
The EB can be supplied without contaminating the EB.

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.

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

By using the TEB supply apparatus having the above-described structure, the method for forming a boron-doped silica film of the present invention provides a high-purity T
EB raw materials can be used. In addition, since the TEB remaining amount of the TEB supply device can be accurately managed,
The TEB of the TEB supply device can be used efficiently,
When the remaining amount of TEB of the TEB supply device becomes small, the operation of replacing the TEB supply device with the next TEB supply device can be performed extremely smoothly.

Next, in the method for forming a boron-doped silica film according to the present invention (hereinafter, tetraethoxysilane (abbreviated as TEOS) will be described as an example of alkoxysilane), TEOS is charged into a TEOS vaporization chamber from a TEOS supply device. Is done. TEOS filled in TEOS vaporization chamber
Is kept at a constant temperature 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 TEB can be controlled.

In the method for forming a boron-doped silica film according to the present invention, TEB is filled into the TEB vaporization chamber from the above TEB supply device. The TEB filled in the TEB vaporization chamber is kept at a constant temperature in order to secure a constant vapor pressure.
Here, the TEB is preferably 0 ° C to 40 ° C, more preferably 5 ° C to 25 ° C. Here, a carrier gas (for example, an inert gas such as N ₂ or Ar) is introduced into the TEB vaporizing chamber to generate a carrier gas / TEB mixed gas, which is then introduced into the reactor. The TEB concentration can be controlled by adjusting the temperature of the TEB, and the ratio of TEB to TEOS can be controlled by adjusting the carrier gas.

In the method for forming a boron-doped silica film of the present invention, an oxidizing gas is introduced into the reactor in parallel with the introduction of the TEB-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%.

In the method for forming a boron-doped silica film of the present invention, a diluent gas (eg, N ₂ , Ar
And the like). By introducing the diluent gas, the concentration of the entire source gas can be adjusted, and the film forming property and the film forming rate can be controlled.
The dilution gas may be directly introduced into the reaction chamber, or may be mixed with any of the source gases.

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).

[0024]

EXAMPLES Next, examples are shown to specifically explain the method for forming a boron-doped 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 boron-doped silica film of the present invention. In FIG. 1, a reactor (chamber) (5) for forming a boron-doped silica film includes a dispersion head (6), a heater (7), and an Si wafer substrate (8) as a substrate on which a boron-doped silica film is formed. And an exhaust port (9). The ozone-containing gas used for the reaction in the reactor (5) is supplied to the flow meter (1a) and the valve (2).
a), it can be introduced into the reactor (chamber) (5) via the ozonizer (3) and the valve (2d). Further, the dilution gas is supplied from a flow meter (1b) and a valve (2
b). Further, the carrier gas can be supplied to the TEB vaporization chamber (4) via the flow meter (1c) and the valve (2c).

Next, the TEB supply device (1) shown in FIG.
8) will be described in detail with reference to FIG. The TEB supply device (18) shown in FIG. 2 is a stainless steel TEB supply device container main body (10) having an inner surface electrolytically polished, and a lid portion that can be joined to the TEB supply device container main body (10). (2
0). Here, the TEB supply device container main body (10) and the lid (20) are, for example, airtightly joined to each other by a joining means such as a bolt and a nut (19). In addition, the lid (20) has a TE for injecting TEB into the TEB supply device container body (10).
A B inlet (12), a TEB supply port (11) for removing TEB from the TEB supply device container body (10), and an optical liquid level sensor (13) are provided. Note that T
The EB inlet (12) has a valve (2g) for controlling the injection of TEB, and the TEB supply port (11) has a valve (2g).
Valves (2f) for controlling the supply of B are provided respectively. 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 TEB supply device main body (10). In addition, the optical liquid level sensor (13) includes a light emitting / receiving device (15).
And the detection circuit (16) are connected, and the detection circuit (1
6) Detection of the remaining amount of TEB based on the signal output from 6), and when the remaining amount becomes equal to or less than a predetermined amount, the supply of TEB is stopped,
It is configured to perform various controls such as stopping the operation of the VD device.

TEOS, which is a Si raw material compound,
It is configured so that it can be introduced into the reactor (5) from the TEOS vaporization chamber (17).

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

The TEB charged in the TEB vaporization chamber (4) is
Set the temperature of the TEOS in the TEOS vaporization chamber (17) to
The vapor pressure was kept constant by keeping the temperature at 5 ° C., and the Si wafer substrate (8) in the reaction chamber (5) was heated by the heater (7) for 4 hours.
Heated to 00 ° C. Next, N ₂ is used as a carrier gas for T.
A gas containing TEB was introduced into the reactor (5) by blowing into the EB vaporization chamber (4) at 1.5 L / min. Further, N ₂ as a carrier gas was blown into the TEOS vaporization chamber (17) at a rate of 3 liter / minute, and a gas containing TEOS was introduced into the reactor (5). At the same time, N ₂ was used as a dilution gas.
The gas was introduced at a rate of 8 liters / minute, and O ₂ gas was passed through an ozonizer (3), and the ozone concentration was set to 5% of O ₂ and introduced.
A 2 μm boron-doped silica film was obtained.

The amount of impurities in the high-purity TEB filled in the TEB vaporization chamber from the TEB 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 15.3 (pieces / milliliter). In addition, the dielectric constant of the obtained boron-doped silica film was measured in order to examine its insulating properties.
Therefore, the large-capacity (64 MB) semiconductor memory is suitable for manufacturing a large-capacity (64 MB) semiconductor memory.

[Comparative Example] In the same manner as in Example 1, except that
A 1.1 μm boron-doped silica film was formed using a TEB supply device having a conventional float type liquid level sensor instead of an optical liquid level sensor as the TEB supply device. When the same operation was performed, the amount of impurities in the high-purity TEB charged in the TEB vaporization chamber from the TEB supply device was measured by measuring the number of particles having a particle size of 0.2 μm or more. The result was 1002 (pieces / milliliter). Further, the dielectric constant of the obtained boron-doped silica film was measured in order to examine the insulating property.
8, which is not practical for the manufacture of a large-capacity (64 MB) semiconductor memory, and the large-capacity semiconductor memory manufactured therefrom was defective.

[0031]

According to the method for forming a boron-doped silica film of the present invention, by using a TEB supply device provided with an optical liquid level sensor, it is possible to use a high-purity TEB raw material having extremely few impurities. A boron-doped silica film having a very low dielectric constant and 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 TEB 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 TEB 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.

[Explanation of symbols]

 1a to 1e: flow meter 2a to 2k: valve 3: ozonizer 4: TEB vaporizing chamber 5: reactor (chamber) 6: dispersion head 7: heater 8: Si wafer substrate 9: exhaust port 10: TEB supply device Container main body 11: TEB supply port 12: TEB injection port 13: Optical liquid level sensor 14: Optical detection probe 15: Emitter / receiver 16: Detection circuit 17: TEOS vaporization chamber 18: TEB supply device 19: Bolt and nut 20: Lid 26: Optical fiber for light projection 27: Optical fiber for light reception 28: Right angle prism 29: Protection tube 30: Conical prism

Claims (8)

[Claims] 1. A step of charging triethyl borate into a vaporization chamber from a triethyl borate supply device; a step of introducing a carrier gas into the vaporization chamber; and a step of introducing a carrier gas / triethyl borate mixed gas from the vaporization chamber to a reactor; A step of introducing an oxidizing gas into the reactor from a supply device; a step of introducing an alkoxysilane gas into the reactor; heating the substrate on which the boron-doped silica film is formed in the reactor to a desired temperature to form boron on the substrate on which the boron-doped silica film is formed. Forming a doped silica film; a method for forming a boron-doped silica film having a step of discharging exhaust gas from a reactor,
A method for forming a boron-doped silica film, wherein the triethyl borate supply device comprises at least one optical liquid level sensor as a liquid amount monitoring means for triethyl borate. 2. The step of introducing an alkoxysilane gas into a reactor comprises introducing a carrier gas into an alkoxysilane vaporization chamber filled with alkoxysilane, thereby causing a mixed gas of the carrier gas and the alkoxysilane to flow. The method for forming a boron-doped silica film according to claim 1, wherein the method comprises introducing the boron-doped silica film. 3. The method according to claim 2, further comprising the step of introducing a diluting gas into the reaction chamber to adjust the concentration of the raw material gas.
3. The method for forming a boron-doped silica film according to item 1. 4. The triethyl borate supply device comprises a container body made of stainless steel whose inner surface is electrolytically polished, and a lid which can be joined to the container body, and the container body and / or the lid are provided. The part comprises a triethyl borate inlet for injecting triethyl borate into the container body, a triethyl borate supply port for removing triethyl borate from the container body, and at least one optical liquid level sensor. The method for forming a boron-doped silica film according to any one of claims 1 to 3, wherein: 5. 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. The method for forming a boron-doped silica film according to claim 4, wherein a light detection probe provided with a prism portion having an internal reflection surface is used. 6. The method for forming a boron-doped silica film according to claim 5, wherein the leading ends of the light projecting optical fiber and the light receiving optical fiber of the light detection probe are widened forward. 7. The method for forming a boron-doped silica film according to claim 4, wherein the internal electrolytic polishing stainless steel container is provided with a lid having a wide opening to such an extent that the interior can be washed. 8. A method of forming a boron-doped silica film according to claim 1 in forming a boron-doped silica film in the manufacture of an electronic component having the boron-doped silica film as a constituent element. Characteristic electronic component manufacturing method.