JPH03204930A - Method of selectively removing insulating film - Google Patents

Abstract

PURPOSE:To enable a specific insulating film only to be selectively etched away by a method wherein the surface of a substrate is kept within the specific temperature range higher than the temperature of a mixed vapor determined according to the kind of the insulating film. CONSTITUTION:The temperature of heating air led in a vapor heating chamber 20 through a feed opening 26 is measured by a temperature controller 36 and then the temperature is adjusted conforming to the measured temperature to keep the temperature of fluoric acid vapor at specific temperature. When the surface of a silicon wafer W is exposed to the fluoric acid vapor, a natural oxide film formed on the silicon wafer W is etched away. At this time, the surface temperature of the silicon wafer W is kept at the temperature of 20 deg.C higher than that of the fluoric acid vapor so as to restrain the condensation of fluoric acid vapor on the surface of silicon wafer W. Consequently, a thermal oxide film, CVD oxide film, etc., formed on the silicon wafer W will be hardly etching away.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention applies to the surface of a silicon wafer, the surface of a polysilicon film, and the surface of an amorphous silicon film (hereinafter, these surfaces are collectively referred to as "silicon layer surfaces"). In particular, it relates to a method for removing an insulating film such as an oxide film formed on a semiconductor device, such as a silicon natural oxide film, a silicon CVD oxide film, or a silicon nitride (Si
Nx) film, phosphorus-doped glass (hereinafter referred to as Nx) film.

rPS (referred to as g) film, boron phosphorus doped glass (hereinafter referred to as
rBPsGj) film, arsenic-doped glass (hereinafter referred to as r
The present invention relates to a method for selectively removing an insulating film such as a film called AgsGJ with respect to another type of insulating film.

[Conventional technology]

In the manufacturing process of semiconductor devices, various types of contamination may occur that may have a negative effect on the operating characteristics of the device. One of these contaminants is the silicon native oxide film that forms on the surface of the silicon layer. . This natural oxide film can easily form on the surface of the silicon layer to a thickness of 10 to 20 people even if the silicon layer is left in the atmosphere. It is also formed secondarily in the etching process.

For example, it is well known in this field that the electrical properties of a thin gate oxide film are greatly affected by the results of pre-treatment of a silicon wafer. Therefore, when forming a thin oxide film such as a gate oxide film on a silicon wafer in a semiconductor device manufacturing process.

It is necessary to remove the native oxide film from the silicon wafer in advance.

Furthermore, it is known that if a native oxide film remains on the surface of a silicon wafer on which electrodes such as source and drain are to be formed, normal electrode functions cannot be obtained. Furthermore, in order to keep the contact resistance low when forming metal electrodes, it is necessary to completely remove the natural oxide film from the surface of the silicon layer.Furthermore, when performing epitaxial growth of silicon, It is necessary to remove the natural oxide film on the surface.

In this way, the silicon natural oxide film formed on the surface of the silicon layer is exposed to especially carbon dioxide during the semiconductor device manufacturing process.
V D (Chemical l/aper Depo
It must be removed before film formation is performed by a method such as photo-coating or sputtering.

In recent years, as a method for removing a silicon native oxide film from the surface of a silicon wafer, a method of cleaning the silicon wafer surface by a vapor phase method using hydrogen fluoride (HF) gas has been studied.

For example, as disclosed in Japanese Patent Publication No. 62-502930, anhydrous hydrogen fluoride gas is supplied to the surface of a silicon wafer together with water vapor (CH1O), and by exposing the silicon wafer surface to them, a high moisture concentration can be achieved. Methods have been proposed for removing various silicon oxide films in an atmosphere.

However, in the manufacturing process of semiconductor devices, various film formation processes are performed on the surface of silicon wafers.
In addition to the above-mentioned natural oxide film, silicon oxide films are formed on silicon wafers by thermal oxidation, CVD, and other various methods.

Various silicon insulating films such as a silicon nitride film, a PSG film, a BPSG film, and an As5O film are also formed. Therefore, in the method disclosed in Japanese Patent Publication No. 62-502930, not only the natural oxide film but also the silicon insulating film that has been painstakingly formed on the wafer may be removed from the wafer surface. happen.

Furthermore, not only silicon wafers but also various semiconductor wafers such as gallium arsenide wafers, when forming some kind of film on a polysilicon film or amorphous silicon film that has already been formed on the substrate, a polysilicon film is used. It is necessary to remove the natural silicon oxide film on the surface of the amorphous silicon film in advance.

Therefore, for example, "Bessatsu Nikkei Microdevice Nn2J
(Nikkei McGraw-Hill, October 1988, pp.
202-207), [Submicron ULSI Process Technology] (Ultra LSI Ultra Clean Technology Symposium 7th Proceedings, ■Realize, July 1988, PP.

173-193) propose a method for selectively removing a silicon oxide film. In those methods,
There is a boundary concentration in which etching occurs when HF, H, and O components exist above a certain concentration, and etching does not occur at all below that concentration, and this boundary concentration differs between a silicon natural oxide film and a silicon thermal oxide film. I'm taking advantage of that. And in these methods,
By controlling the HF gas concentration in the diluent nitrogen (N) gas under conditions where the concentration of H and O components in the atmosphere is kept extremely low, only the native oxide film can be selectively removed from the surface of the silicon wafer. I'm trying to remove it.

[Problem to be solved by the invention]

However, as mentioned above, there is a method of selectively removing only the native oxide film from the silicon wafer surface by controlling the HF gas concentration in the diluent N2 gas in a system with extremely low H and O in the atmosphere. It is required to accurately dilute HF gas with N2 gas to generate diluted HF gas with a concentration of several vol, %, and the amount of H and O in the atmosphere must be extremely small.

For this reason, the configuration of the entire device becomes complicated, and.

There is a problem that it is not easy to control.

The technical object of the present invention is to enable selective removal of only a desired insulating film by a method that is relatively simple and easy to implement compared to the conventional methods described above. More specifically, it is possible to transfer a desired insulating film from at least two types of insulating films formed on the surface of a substrate to another insulating film without requiring extremely low moisture in the atmosphere. It makes it possible to selectively remove
In addition, it is possible to selectively remove a desired insulating film from the substrate surface with HF gas without being required to dilute the HF gas accurately, and furthermore, HF and H,
An object of the present invention is to provide a method that makes it possible to selectively remove a desired insulating film from a substrate surface using a mixed gas of HF gas and water vapor without depending on a mixing ratio of 0.

[Means to solve the problem]

The method for selectively removing an insulating film on a substrate surface according to the present invention includes:
Hydrofluoric acid (an aqueous solution of liquid hydrogen fluoride, hereinafter referred to as
A mixed vapor containing at least hydrogen fluoride and water (hereinafter referred to as "hydrofluoric acid vapor"), such as a mixed vapor of hydrogen fluoride gas and water vapor (hereinafter referred to as "hydrofluoric acid vapor"), is applied to the surface of the substrate. At that time, the surface temperature of the substrate is
An insulating film is formed on the surface of the substrate together with the insulating film so as to maintain the temperature within a predetermined temperature range that is higher than the temperature of hydrofluoric acid vapor and determined by the type of insulating film. This type of insulating film is selectively removed.

[For production]

By the method according to the present invention having the above-described structure, for example, selective removal of a silicon natural oxide film with respect to a silicon thermal oxide film proceeds through the following process.

Generally, when hydrofluoric acid vapor is supplied to the surface of a silicon layer,
Hydrofluoric acid vapor is adsorbed on the surface of the silicon layer. The silicon natural oxide film formed on the surface of the silicon layer is composed of H, O
In the presence of S i O, +6HF−+H, S i F
, +2H,0 proceeds and is etched. This etching reaction causes fluorosilicic acid (H, Sip
s) is formed. The formed H, SiF, will exist in high concentration in the liquid film that covers the surface of the silicon natural oxide film, and eventually evaporate to form SiF, gas, and HF.
It becomes a gas and is removed from the surface of the silicon layer.

However, in the method according to the present invention, the surface of the silicon layer,
That is, the surface temperature of a silicon wafer, a substrate having a polysilicon film, or an amorphous silicon film is higher than the temperature of hydrofluoric acid vapor.

For example, 10°C or more and 50°C or less than the temperature of hydrofluoric acid vapor,
Preferably, the temperature is maintained at a temperature range of 12°C or higher and 40°C or lower. Therefore, when hydrofluoric acid vapor is supplied to the surface of the silicon layer, adsorption of the hydrofluoric acid vapor to the surface of the silicon layer is suppressed. As a result, for the natural oxide film formed on the surface of the silicon layer, the etching action as shown in the above reaction equation is not significantly hindered, but for the silicon thermal oxide film, the etching reaction is almost stopped.

The reason for this difference in reactivity between the natural oxide film and the thermal oxide film is not clearly understood.

This is thought to be due to the difference in the quality of the two films, the difference in the amount of water in the two films, or the influence of water molecules adsorbed on the oxide film.

As described above, only the natural oxide film on the surface of the silicon layer is selectively etched and removed from the surface of the silicon layer.

The above explanation takes as an example a case where a silicon natural oxide film is selectively removed from a silicon layer surface with respect to a silicon thermal oxide film, but other insulating films, such as a silicon CVD oxide film, a PSG film, a BPSG film, etc. Selective removal of other types of insulating films, such as silicon nitride films, silicon nitride films, etc., can also be performed by the method of the present invention through a process similar to that described above.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described.

FIG. 1 is a schematic configuration diagram showing an example of a silicon wafer cleaning apparatus for carrying out the method according to the present invention. The apparatus shown in FIG.
An inner pipe 12 having a gas/steam supply port 14 and an exhaust port 16 is disposed through it. In addition, the supply port 14 of the inner tube 12 is provided with eight N, gas, HF gas and H,
A gas supply unit 38 for supplying O vapor is connected in communication.

The inner tube 12 is opened in the middle of the outer container 10, and a wafer heating chamber 18 and a steam heating chamber 20 are disposed in the opening, facing each other. The wafer heating chamber 18 is provided with a heated air supply port 22 and an exhaust port 24 . Further, the steam heating chamber 20 is provided with a supply port 26 and an exhaust port 28 for heating air. and,
The steam heating chamber 20 has an airtight structure,
An ultraviolet irradiation lamp 30 and an end point sensor 32 are housed inside.

At the opening of the wafer heating chamber 18 facing the opening of the inner tube 12, the silicon wafer W to be cleaned is placed with the surface to be cleaned (the upper surface in the figure) facing the passage side of the inner tube 12. It is installed.

The silicon wafer W isolates the inner tube I2 from the wafer heating chamber 18 so that they do not communicate with each other.

An internal flow path for gas and steam is formed by the inner tube 12 and the silicon wafer W and the wall surface of the steam heating chamber 20 that faces the silicon wafer W.

In addition, the wafer heating chamber 18 measures the surface temperature of the silicon wafer W, and based on the measured value, the wafer heating chamber 18 measures the surface temperature of the silicon wafer W.
A temperature controller 34 is provided for maintaining the surface temperature of the silicon wafer W at a desired temperature by adjusting and controlling the temperature of the heated air supplied through the supply ports 22 of 8.

In the steam heating chamber 20, the temperature of the steam flowing inside the inner tube 12 is measured, and the temperature is measured based on the measured value.

A temperature controller 3 for maintaining the temperature of the steam in the inner tube 12 at a predetermined temperature by adjusting and controlling the temperature of the heated air supplied through the supply port 26 of the steam heating chamber 20.
6 (details of the control mechanism are omitted from illustration and explanation).

Next, one example of the configuration of the gas supply unit 38 will be described with reference to FIG. 2.

The gas supply unit 38 shown in the figure includes a hydrofluoric acid tank 100 for storing hydrofluoric acid used for cleaning processing. This hydrofluoric acid tank 100 is provided with one pipe line 104 and one pipe line 106 which are connected to a hydrofluoric acid supply source and a N2 gas supply source (not shown), respectively. Conduit 104
A valve 108 is installed in the hydrofluoric acid tank 1.
By operating the valve 108 in response to a signal from the level controller 110 attached to the hydrofluoric acid tank 100, the level of the hydrofluoric acid stored in the hydrofluoric acid tank 100 is adjusted to be approximately constant. The conduit 106 also includes a mass flow controller 112. Noku valve 114
．． A heater 116 and a temperature controller 118 for the heater 116 are also provided. Then, based on the signal from the pressure gauge 120 attached to the hydrofluoric acid tank 100, the valve 114 is adjusted to supply N2 gas from the N2 gas supply source to the hydrofluoric acid tank 100 through the pipe line 106.
The valve 14 is interposed in an exhaust pipe 144 that communicates with the internal space of the hydrofluoric acid tank 100.
6 and performs appropriate evacuation, the gas pressure inside the hydrofluoric acid tank 100 is controlled to be kept constant.

In addition, the hydrofluoric acid tank 100 has a circulation pipe 122°12
4 is attached, and a pump 126 is interposed in the middle of the circulation pipes 122 and 124, and the pump 126
By driving the hydrofluoric acid tank 100, the hydrofluoric acid in the hydrofluoric acid tank 100 is stirred.

Further, a drain pipe 128 is connected to the bottom of the hydrofluoric acid tank 100.

Furthermore, a heater 130 and a cooling coil 132 are arranged inside the hydrofluoric acid tank 100.
Cooling water is supplied to the pipe 134 from a cooling water supply source (not shown).
The water that is sent through the cooling coil 132 and flows through the cooling coil 132 is
It passes through a pipe line 136 and joins the drain pipe 128.

A temperature sensor 138 is attached to the hydrofluoric acid tank 100, and a signal corresponding to the temperature of the hydrofluoric acid detected by the temperature sensor 138 is sent to the temperature controller 1.
40, and the control signal from the temperature controller 140 controls the energization of the heater 130 and the opening/closing operation of the valve 142 installed in the cooling water supply piping 134. It is configured to adjust the temperature of hydrofluoric acid to a predetermined temperature.

The gas supply unit 38 further includes a pipe line 148 that communicates with an N2 gas supply source (not shown), and a pipe line 150 that communicates with the hydrofluoric acid tank 100, which joins to the supply port 14 of the inner pipe 12. It has a conduit 152 that communicates with it. A mass flow controller 154 is connected to the conduit 148.
, a valve 156 , and a heater 158 and a temperature controller 160 for controlling the heater 158 . Further, a valve 162 is provided in the conduit 150. By adjusting the valves 156 and 162, the N2 gas supplied from the N2 gas source through the pipe 148 or the pipe 15 from the hydrofluoric acid tank 100 is controlled.
Hydrofluoric acid vapor supplied through the pipe 152 is selectively supplied through the pipe 152.
It is supplied to the supply port 14 of the inner tube 12 through.

Returning to FIG. 1, the end point sensor 32 disposed inside the steam heating chamber 20 is for detecting the end point of the cleaning process. and a light receiving fiber (none of which are shown). In this end point sensor 32, the light emitting fiber is connected to the silicon wafer W.
When coherent light is irradiated onto the surface of the silicon wafer W, the irradiated light is reflected by the upper surface of the coating on the silicon wafer W and the lower surface of the coating, and each of the reflected lights enters the light-receiving fiber. At this time, the two reflected lights will interfere with each other due to their optical path difference, but since the optical path difference is equal to twice the thickness of the coating, the progress of the process can be determined by examining the intensity of one reflected light. You will be able to do that. 1. Normally, the intensity of the reflected light is converted into a voltage value using a photodiode or the like, and the end point of the process is detected by examining changes in the voltage level.

In order to clean and remove the native oxide film on a silicon wafer using the apparatus configured as described above, first, the silicon wafer W is carried into the outer container IO and set at the predetermined position shown in FIG. Carrying the silicon wafer W into the outer container 10 is as follows:
This is carried out using a mechanical conveyor or the like that can hold the wafer W by vacuum suction or the like.

Next, when the surface of the silicon wafer W is irradiated with ultraviolet rays from the ultraviolet irradiation lamp 30, excited oxygen generated by this ultraviolet irradiation causes

Organic substances that are impurities adhering to the surface of the silicon wafer W are decomposed and removed. Regarding the fact that such an effect can be obtained by ultraviolet irradiation, for example, Japanese Patent Application Laid-open No. 1983
This is disclosed in Japanese Patent No.-33824 and the like.

After that, N2 gas is introduced into the inner tube 12 from the supply port 14, and the inside of the inner tube 12 is purged with N gas. The N2 gas is introduced into the inner tube 12 by opening the valve 148 and closing the valve 162 in the gas supply unit 38 shown in FIG. At this time, the gas introduced into the inner tube 12 may be any gas other than N2 gas as long as it is inert to the surface of the silicon layer to be treated and the inner wall surface of the chamber.

While subsequently purging the inside of the inner tube 12 with N2 gas, heated air is introduced into the wafer heating chamber 18 from the supply port 22 to heat the silicon wafer W. At this time, the surface temperature Ts of the silicon wafer W is set to be 20°C or more higher than the temperature Tv of the hydrofluoric acid vapor subsequently introduced into the inner tube 12, that is, so that Ts-Tv≧20°C. The temperature is controlled by a temperature controller 34. The temperature controller 34 measures the surface temperature of the silicon wafer W, and based on the measured value, the temperature controller 34 supplies the wafer heating chamber 1 through the supply port 22.
The temperature of the heated air supplied into the 8 is adjusted.

Then, by closing the valve 156 and opening the valve 162, hydrofluoric acid (HF/H2 gas is used instead of N2 gas).
Steam of O) is introduced into the inner tube 12 through the supply port 14. At this time, the temperature of the heated air introduced into the steam heating chamber 20 through the supply port 26 is measured by the temperature controller 36, and the temperature is adjusted based on the measured temperature. The temperature of the acid vapor is maintained at a predetermined temperature.

Hydrofluoric acid vapor is introduced into the inner tube 12, and the silicon wafer W
When the surface of is exposed to hydrofluoric acid vapor.

As a result, the natural oxide film formed on the silicon wafer W is etched and removed from the surface of the silicon wafer W. At this time, since the surface temperature of the silicon wafer W is maintained at least 20° C. higher than the temperature of the hydrofluoric acid vapor, condensation of the hydrofluoric acid vapor onto the surface of the silicon wafer W is suppressed.

As a result, a thermal oxide film formed on the silicon wafer W,
Etching of CVD oxide films, etc. hardly progresses.

Once the natural oxide film has been removed from the surface of the silicon wafer W, the flow path is switched again to introduce N2 gas into the inner tube 12 to purge the inside of the inner tube 12 with the N2 gas. Completion of natural oxide film removal.

It is detected by monitoring the output of the endpoint sensor 32 as described above. While successively purging the inside of the inner tube 12 with N2 gas, ultraviolet rays (wavelength: 18
4.9 nm, 253.7 nm). As a result, fluorine (F) is removed from the surface of the silicon wafer W. Then, after roughly purging the inside of the inner tube 12 with N2 gas for a predetermined period of time, the silicon wafer W is carried out from the outer container 10 by an unillustrated carrying mechanism.

Further, when configuring the apparatus as shown in FIG. 1, the partition wall of the steam heating chamber 20 in which the ultraviolet irradiation lamp 30 and the end point sensor 32 are installed is formed of transparent quartz glass.

In this case, in order to prevent corrosion of the quartz glass by the hydrofluoric acid vapor, it is preferable to maintain the surface temperature of the quartz glass partition wall at least 20° C. higher than the temperature of the hydrofluoric acid vapor.

Note that the steam supplied from the steam supply port 14 may be a mixed vapor of hydrogen fluoride gas and water vapor instead of the vapor of an aqueous solution of hydrogen fluoride, and may be a vapor containing at least hydrogen fluoride and water. .

Next, an example of an experiment conducted using an experimental apparatus having the same basic configuration as the cleaning apparatus described above will be described.

In this experiment, as shown in FIG. 3, a cylindrical body 40 for heating wafers was used, which was equipped with a heater 42 inside, an exhaust port 44, and an open end surface, and a cylindrical body 40 for heating wafers, which contained hydrofluoric acid and had an exhaust port 48. An experimental apparatus was used having a container 46 provided with a. Then, the silicon wafer W is attached to the open end surface of the wafer heating cylindrical body 40, and the detection end of the temperature sensor 50 is brought into contact with the surface of the wafer W. Also,
The tip of the wafer heating cylindrical body 40 is inserted obliquely into the container 46 to attach the cylindrical body 40 to the container 46 in an airtight manner.

The experimental apparatus having the above configuration is placed in a draft chamber (local exhaust chamber) (not shown), and an operator outside the draft chamber operates the experimental apparatus placed inside the draft chamber. For that purpose, in front of the fume hood chamber.

An opening is provided for working.

Air within the draft chamber is forcibly exhausted to the outside through an exhaust port provided in the ceiling of the chamber. By evacuating the inside of the draft chamber in this way, the container 4
The steam V in 6 is exhausted through the exhaust port 48.

The silicon wafer W is held tilted within the container 46,
As a result, the flow of the steam V in the container 46 is not obstructed, the steam V evenly contacts the surface of the wafer W, and the processing on the surface of the wafer W is uniformly performed over the entire surface.

In addition, the inside of the draft chamber is kept at room temperature (22°C),
Therefore, the temperature of the hydrofluoric acid and the hydrofluoric acid vapor V in the container 46 is also maintained at room temperature. On the other hand, the surface temperature of the silicon wafer W is adjusted by adjusting the amount of air heated by the heater 42 based on the detection result of the temperature detector 50. As the hydrofluoric acid, a 50% aqueous solution of hydrogen fluoride is used, and the concentration of HF contained in the hydrofluoric acid vapor V is 1.5 wt%. Further, the inside of the container 46 is under atmospheric pressure.

First, in the first experiment, a silicon wafer (P type (100)) with a diameter of 6 inches was coated with a silicon thermal oxide film having a thickness of approximately 5,000 wafers. Then, etching was performed using the above apparatus on silicon wafers W whose surface temperature was kept at room temperature (22°C) and 65°C, and the etching rates were measured and compared to perform evaluation. Ta. The measurement points are 27 at 5-im intervals along a specific direction on the wafer surface so that each wafer has a common position on the wafer surface, and the average of the etching rate measurements at each measurement point is calculated. I did it like that.

Furthermore, an optical interference type film thickness meter using a microspectroscope was used to measure the film thickness. The accuracy of this film thickness meter is ±10 people.

As a result, when the surface temperature of the silicon wafer W was maintained at 22° C., the etching rate of the silicon thermal oxide film was 1,323 people/min. On the contrary,
When the surface temperature of the silicon wafer W was maintained at 65° C., the silicon thermal oxide film was hardly etched, and the etching rate was 0.68 people/min.

Next, an experiment was conducted to evaluate whether the natural oxide film would be etched when the surface temperature of the silicon wafer W was maintained at 65°C.

As described above, a silicon wafer (P type (100)) with a diameter of 6 inches was used as the sample body, and an ellipsometer (a film thickness measuring device based on ellipsometry) was used to measure the film thickness.

As a result of the experiment, the thickness of the natural oxide film before treatment was 14.
What used to be 7 people became 5.0 people after the treatment. This confirmed that the native oxide film was etched and almost completely removed from the silicon wafer.

Regarding the evaluation of this experimental result, I would like to make some additional explanations.
Xl is the value measured by an ellipsometer.

X-ray photoelectron spectroscopy (Electron 5pectr
Oscopy for Chemical Analysis
is : ES CA ) is the measured value by Xt, then the following relationship exists between the one-side measured value

X, -X, Dou 3.5 to 5.0 people As can be seen from this relationship, the value measured by the ellipsometer of 5.0 people means that it cannot be detected by measurement by ESCA. That is, the above-mentioned experimental results are considered to indicate a surface state in which almost no native oxide film exists.

The above two experimental results confirmed that by adjusting the surface temperature of the silicon wafer, it is possible to selectively remove only the natural oxide film from the silicon wafer while leaving the thermal oxide film on the silicon wafer.

Next, in a second experiment, we investigated how the etching rate changes when the surface temperature of the silicon wafer is varied. As a sample object, about 500 yen was placed on a silicon wafer (P type (100)) with a diameter of 6 inches.
A thermally oxidized silicon film having a thickness of 1,000 yen was used. The processing time was uniformly 60 seconds in all cases. Measurement points are set at 27 locations at 5-inch intervals along a specific direction on the wafer surface so that each wafer has a common position on the wafer surface, and evaluation is performed based on the average value of the etching rate measured at each measurement point. I did it like that. Further, the above-mentioned optical interference type film thickness meter was used to measure the film thickness before and after the treatment. The accuracy of the film thickness meter was ±10 people. Temperature parameters are 23℃, 35℃, 37.5℃, 4
Five temperatures were used: 5°C and 65°C, and the accuracy of temperature control was approximately ±1°C.

The experimental results are shown in FIG. 4. As can be seen from FIG. 4, as the surface temperature of the silicon wafer increases, the etching rate of the thermal oxide film decreases, and at 65 DEG C., no etching occurs at all. The boundary temperature at which most of the thermal oxide film is etched is 3.
It is around 7.5℃.

From this result, it was concluded that etching of the thermal oxide film can be suppressed by adjusting the surface temperature of the silicon wafer. Furthermore, it has been confirmed that the etching reaction of the thermal oxide film on the silicon wafer can be stopped by increasing the surface temperature of the silicon wafer W by about 15° C. or higher than the temperature of the hydrofluoric acid vapor V (room temperature).

5 and 6 show another example of the configuration of the apparatus for carrying out the method of the present invention, FIG. 5 is an overall schematic longitudinal sectional view,
FIG. 6 is an enlarged longitudinal sectional view of the main parts of the device.

The apparatus shown in FIG. 5 is an improved version of the experimental apparatus described in the above embodiment. This device is provided with a hydrofluoric acid tank 202 as a cleaning treatment liquid storage section for storing hydrofluoric acid, which is a cleaning treatment liquid, in a housing 200. The upper part of the hydrofluoric acid tank 202 is sealed with a cover 204, and the A steam generating section 206 that generates steam from hydrofluoric acid is formed above the acid tank 202.

An inner housing 208 is provided below the hydrofluoric acid tank 202 and inside the housing 200 in close contact with the downward surface of the bottom wall 202a of the hydrofluoric acid tank 202.
Within its inner housing 208 is a substrate W to be cleaned.
A substrate holding means 210 for holding is provided, and
A vapor supply section 212 that supplies hydrofluoric acid vapor is provided between the downward surface of the bottom wall 202a and the substrate W.

The substrate holding means 210 is provided with a hot plate 214 rotatable around a vertical axis and equipped with a heater (not shown), as shown in an enlarged vertical cross-sectional view of the main part in FIG. The support shaft 21 is attached to the hot plate 214.
6 are integrally connected. And the spindle 2
16 and an electric motor 2 provided outside the housing 200.
18 are interlocked and connected via a belt type transmission mechanism 220.

A vacuum suction path 222 is formed inside the hot plate 214 and the support shaft 216, and is configured to vacuum suction the substrate W. The heater installed in the hot plate 214 is controlled by a temperature control means (not shown), and the surface temperature of the hot plate 214 is controlled by the steam supply unit 212.
The structure is such that the temperature can be maintained at the same temperature as or higher than the ambient temperature.

At approximately the same level as the top surface of the hot plate 214, the inner housing 208 and the housing 200 have openings 208a and 200a for loading and unloading the substrate W, respectively.
is formed, and an opening/closing shutter 224 is attached to each of the openings 208a, 200a.

A flexible arm-type substrate transport mechanism 226 installed outside the opening 200a of the housing 200 is moved forward and backward to above the hot plate 214, so that the substrate W can be taken in and out of the inner housing 208. That is, with the substrate W being sucked and held by the substrate transport mechanism 22G, the substrate W is carried through both openings 200a and 208a onto the hot plate 214, and then the substrate transport mechanism 226 is retreated to the outside of the housing 200. and,
While closing the shutters 224, 224, the substrate W is suctioned and held on the hot plate 214. On the other hand, when taking the substrate W out of the housing 200, the shutters 224, 224 are opened, the substrate W is held by the substrate transport mechanism 226, and the opening 208 is
The substrate W can be taken out of the housing 200 through the holes 200a and 200a.

The shutters 224, 224 are configured to be opened and closed by meshing a binion gear (not shown) with a rack gear (not shown) formed on each shutter, and rotating the binion gear with a transmission motor 224a.

Note that as the shutters 224, 224, any structure may be adopted as long as it allows transport of the substrate W and formation of an airtight space.

As shown in FIG. 6, inside the hydrofluoric acid tank 202, a hot water pipe 228 is disposed and supported by a holder (not shown), and inside the bottom wall 202a of the hydrofluoric acid tank 202, a hot water flow path 230 is provided. It is formed.

Then, the hot water pipe 2 is connected to the hot water supply pipe 232 shown in FIG.
Hydrofluoric acid stored in the hydrofluoric acid tank 202 is heated and evaporated by circulating hot water through a circulation path leading to a hot water exhaust pipe 234 via a hot water flow path 28 and a hot water flow path 230. The hot water pipe 228 and the hot water flow path 23
0 constitutes a heating means for heating and evaporating hydrofluoric acid.1 In the figure, S1 indicates a temperature sensor that measures the temperature of hydrofluoric acid in the hydrofluoric acid tank 202, and based on the measured temperature, The amount of hot water flowing into the hot water pipe 228 and the hot water flow path 230 is maintained at 1 IjfilL, and the temperature of hydrofluoric acid is maintained at a temperature below the boiling point.

In addition, when using a cleaning treatment liquid with a low boiling point, the hot water piping 228 may be omitted and the cleaning treatment liquid etc. may be heated only through the hot water channel 230. Medium oils can also be used.

As shown in FIG. 5, the hydrofluoric acid tank 202 is formed with an overflow channel 236, and an automatic on-off valve 2 is provided at a midway point in the overflow channel 236.
At the initial stage and during hydrofluoric acid replenishment, hydrofluoric acid with a concentration of 39.4% is supplied from a storage tank (not shown) through the hydrofluoric acid supply pipe 240 until it overflows, and when the overflow occurs, the valve 242 When the tank 202 is closed, an appropriate amount of hydrofluoric acid is stored in the hydrofluoric acid tank 202. Note that, since it is preferable that the hydrofluoric acid supplied from the hydrofluoric acid supply pipe 240 be heated to a predetermined temperature in advance, a temperature control means is provided in the hydrofluoric acid supply pipe 240 if necessary.

After an appropriate amount of hydrofluoric acid is stored in the hydrofluoric acid tank 202, the automatic opening/closing valve 23B is closed to prevent hydrofluoric acid vapor from leaking through the overflow channel 236 during cleaning processing. There is. Hydrofluoric acid is replenished during the cleaning process at an appropriate time based on the number of substrates W to be processed and the processing time. As a configuration for supplying an appropriate amount of hydrofluoric acid into the hydrofluoric acid tank 202, for example, a liquid level gauge is provided in the hydrofluoric acid tank 202, and the liquid level gauge detects when the hydrofluoric acid has decreased to a set amount. Based on this, a set amount of hydrofluoric acid may be supplied.

Further, the upper end of the steam supply passage 244 is opened at a higher position than the position facing the overflow passage 236, that is, so as to be connected to the steam generation section 206, and the lower end of the steam supply passage 244 is opened. Part is hydrofluoric acid tank 202
The steam supply section 21 is located on the downward surface side of the bottom wall 202a.
2, and an opening/closing means 246 for automatically opening and closing the steam supply path 244 is provided.

A carrier gas supply pipe 248 that supplies nitrogen (N2) gas as a carrier gas is provided on the upper side of the steam generation section 206.
are connected in communication, and a valve 250 is interposed in the carrier gas supply pipe 248.

Through this carrier gas supply pipe 248, heated N2
By sending the gas to the steam generating section 206, the hydrofluoric acid vapor stored in the steam generating section 206 is sent to the steam supply path 244.

Further, a mixed gas supply pipe 252 is connected to communicate with the steam supply section 212 to supply N2 gas as a mixing gas, and a valve 254 is interposed in the mixed gas supply pipe 252.

The carrier gas supply pipe 248 and the mixed gas supply pipe 25
Although not shown, each of the tubes 2 is provided with a temperature control means for maintaining the temperature of the N2 gas flowing therein at a set temperature.

The vapor supply unit 212 is connected to the bottom wall 202 of the hydrofluoric acid tank 202 by a perforated plate 256 for diffusion supply.
A vapor space 258 is formed between the

A steam supply path 244 is connected to the steam space 258 to supply hydrofluoric acid vapor to the substrate W on the hot plate 214.
It is configured so that it can be applied to the surface of In this steam supply section 212, the temperature of the hydrofluoric acid vapor is maintained at a temperature exceeding the dew point by heating from the hot water flow path 230 formed in the bottom wall 202a of the hydrofluoric acid tank 202 and heating from the hot plate 214. It has become.

According to the device configured as described above, the hydrofluoric acid tank 202
, steam generation section 206, steam supply section 212. In addition, since the steam supply path 244 and the like that communicate the steam generation section 206 and the steam supply section 212 are arranged close to each other in the vertical direction, it is possible to efficiently heat and control the temperature of them all together. , it is possible to easily prevent condensation of cleaning steam on them.

Further, as shown in FIG. 5, a first exhaust pipe 262 in which a first flow control valve 260 is inserted is connected to the inner space of the inner housing 208, and the inner housing 208 and the outer housing 200 are connected to each other. In a space surrounded by
A second exhaust pipe 266 with a second flow control valve 264 inserted therein.
are connected. In addition, the first and second exhaust pipes 2
62 and 266 are each connected to a suction/exhaust device (not shown). The opening degree of the first flow rate control valve 260 is set to be larger than the opening degree of the second flow rate control valve 264, and the amount of suction and exhaust into the inner housing 208 is adjusted between the inner housing 208 and the outer housing 2.
The amount of suction and exhaust gas is controlled so that it is larger than the amount of suction and exhaust gas into the space surrounded by 00, and the leakage of hydrofluoric acid vapor discharged after being supplied to the substrate W to the outside is effectively prevented. An exhaust control means is configured.

Note that the displacement of the inner housing 208 is the same as that of the outer housing 2.
In order to make the displacement larger than 00.

The diameter of the exhaust pipe 262 is made larger than the diameter of the exhaust pipe 266, and both the exhaust pipes 262 and 266 are connected to the same suction/exhaust device, or the exhaust pipes 262 and 266 are connected to different suction/exhaust devices. configuration etc. can be adopted.

Next, an example of an experiment conducted using the apparatus shown in FIGS. 5 and 6 described above will be described.

In the apparatus shown in Figures 5 and 6, a 39.4% aqueous solution of hydrogen fluoride (azeotropic composition at 20°C) is used as the hydrofluoric acid, and the concentration of HF contained in the hydrofluoric acid vapor is Q,
It is 48wt%.

Further, the inside of the housing 200 is under atmospheric pressure.

For the experiment, a silicon wafer (P type (1
00)) A PSG film with a thickness of approximately 4,000 wafers was deposited on a silicon wafer with a diameter of 6 inches, and a BPSG film with a thickness of approximately 6,000 wafers was deposited on a silicon wafer with a diameter of 6 inches. , a silicon nitride (Si,N,) film with a thickness of 1,500 wafers deposited on a silicon wafer with a diameter of 5 inches;
A silicon thermal oxidation (th-8ift) film was deposited on a 5-inch diameter silicon wafer, and a 20,000-th-thick silicon CVD oxidation (CVD-8ift) film was deposited on a 5-inch diameter silicon wafer.
5i0. ) film was deposited, and a silicon wafer with a diameter of 6 inches was coated with a natural silicon oxide film (Natfve-Oxide) with a thickness of about 15 people.Six types of specimens were prepared. .

To form a natural silicon oxide film on a silicon wafer, the silicon wafer is heated with an ammonia-hydrogen peroxide solution (NH4
0H (28%): H, O, (30%): H, O=
1:1:5).

Then, while the temperature of hydrofluoric acid was maintained at 22°C, the surface temperature of the silicon wafer was gradually increased from 22°C, and the surface temperature of the wafer was maintained at the required temperature, respectively, as shown in Figures 5 and 6. Etching was performed using the apparatus shown in the figure, and the etching rate was measured. For the PSG film, BPSG film, and silicon thermal oxide film, the measurement points were 29 at 5-point intervals along a specific direction on the wafer surface (17 points with the center of the wafer as the reference point).
The silicon nitride film and the silicon CVD oxide film were placed at 21 locations at intervals of 5 cm along a specific direction on the wafer surface (within the range of 150 m to +70 m using the center of the evaporator as a reference point). For silicon wafers with a silicon natural oxide film (within the range of +50 degrees), the center of the wafer is the center of the circle. 21 locations selected on three concentric circles equally spaced in the radial direction (location III is at the center of the wafer) were used as measurement points.

Then, the average of the etching rate measurements at each measurement point was determined, and the average value was taken as the etching rate value for each silicon wafer on which each type of insulating film was formed.

In addition, the film thickness is measured for PSG film, BPSG film, and silicon CVD oxide film respectively.

An optical interference type film thickness meter using an am spectrometer was used. The accuracy of this film thickness meter is ±10 people. Regarding the silicon thermal oxide film, the film thickness was measured using both the optical interference type film thickness meter and the ellipsometer (see Section 7 below).
- The measurement results shown in Figure 1 were obtained using an optical interference type film thickness meter, and the measurement results shown in Figure 8 were obtained using an ellipsometer). An ellipsometer was used to measure the film thickness.

The results of the experiment are shown in Figures 7-1, 7-2, and 8. In these graphs, the horizontal axis represents the difference between the temperature of hydrofluoric acid (22° C.) and the surface temperature of the silicon wafer, and the vertical axis represents the etching rate.

From FIG. 7-1 and FIG. 7-2, PSG film.

It was found that for all of the BPSG film, silicon thermal oxide film, and silicon CVD oxide film, the amount of etching per unit time changes depending on the temperature difference between the hydrofluoric acid vapor and the silicon wafer surface. As the temperature difference increases, the etching rate decreases. Also, P
The SG film and the BPSG film continue to be etched while drawing similar etching rate curves until the temperature difference becomes 150'C or more. On the other hand, a silicon thermal oxide film will not be etched if the temperature difference is about 12°C or more, and a silicon CVD oxide film will not be etched if the temperature difference is about 18°C or more.

In this way, it has been found that the etching rate curves are completely different depending on the type of insulating film formed on the silicon wafer. By utilizing this fact, it becomes possible to selectively remove two types of insulating films from the silicon wafer surface. From Figure 7-1, silicon thermal oxide film and PSG
Selectivity between the PSG film and the BPSG II film is observed over a wide temperature range, allowing the PSG film or BPSG film to be selectively removed from the wafer surface relative to the silicon thermal oxide film. Then, silicon thermal oxide film and PSG film or B
The selectivity between the PSG film and the wafer surface is particularly high when the temperature difference between the hydrofluoric acid vapor and the wafer surface is in the range of 14 to 18°C. can be removed. Furthermore, the selectivity between silicon CVD oxide film and PSG film or BPSG film is similarly observed over a wide temperature range, and P
The SG film or BPSG film can be selectively removed from the wafer surface relative to the CVD oxide film, especially when the temperature difference is 18
The selectivity is maximum in the range of ~20°C.

Regarding PSG films and BPSG films, as shown in Figure 7-1, selectivity is rarely observed in the range where the temperature difference between the hydrofluoric acid vapor and the wafer surface is small. , as shown in Figure 7-2, the selectivity increases when the temperature difference exceeds 85°C, and when the temperature difference exceeds 150°C, the BPSG of the PSG film and the BPSG film increases.
Since the film is no longer etched, if there is a temperature difference of 150° C. or more between the hydrofluoric acid vapor and the wafer surface, it becomes possible to selectively remove the PSG film with respect to the BPSG film.

Figure 8 shows the results of an experiment using an ellipsometer to measure the thickness of an insulating film, while Figure 7 shows the results of an experiment using an optical interference type film thickness meter using a microspectroscope to measure the film thickness.
As you can see from Figure 1, when measuring the film thickness using an optical interference film thickness meter, if the temperature difference between the hydrofluoric acid vapor and the wafer surface is about 12°C or more, silicon heat that appears not to be etched can be detected. The oxide film is also slightly etched (3 people/min with a temperature difference of 12°C, 1 person/min with a temperature difference of 18°C.

It can be seen that a temperature difference of 38°C results in 0.8 people/m1n). In this way, in this experiment, more accurate results could be obtained than the experimental results shown in FIG. 4 obtained using the experimental apparatus shown in FIG. 3 described above. From Figure 8, the etching rate of both the silicon thermal oxide film and the silicon natural oxide film gradually decreases as the temperature difference between the hydrofluoric acid vapor and the silicon wafer increases, but the etching rate curve of the natural oxide film is smaller than that of the silicon wafer. The etching rate curve of the thermal oxide film is shifted in the direction of a larger temperature difference, and when the temperature difference is equal, the etching rate of the natural oxide film is always higher than the etching rate of the silicon thermal oxide film.

Furthermore, as for the silicon nitride film, even if the temperature difference between the hydrofluoric acid vapor and the silicon wafer is small, the etching rate is lower than that of other insulating films.

When the temperature difference exceeds about 11°C, the etching rate becomes larger than that of the silicon thermal oxide film, and when the temperature difference exceeds about 20°C.
If it becomes larger, the etching rate becomes higher than that of the silicon natural oxide film.

From Figures 7-2 and 8 showing the results of experiments conducted using the apparatus shown in Figures 5 and 6, it can be seen that the surface temperature of the silicon wafer is lower than the temperature of the hydrofluoric acid vapor. It is concluded that by keeping the temperature high and controlling the adsorption of hydrofluoric acid vapor onto the wafer surface, it is possible to obtain the selectivity shown below between various insulating films of different types and the same dirt floor.

(i) Temperature that maintains the surface temperature of the silicon wafer higher than the temperature of hydrofluoric acid vapor (hereinafter referred to as "temperature difference")
The silicon natural oxide film can be selectively removed with respect to the silicon thermal oxide film when the temperature difference is in the range of 10° C. or more and 50° C. or less, preferably 12° C. or more and 40° C. or less. However, the preferred range of temperature difference varies somewhat depending on the silicon thermal oxidation and the formation conditions of the silicon natural oxide film.

(if) The silicon CVD oxide film can be selectively removed with respect to the silicon thermal oxide film within a temperature difference of 10°C or more and 30”C or less, preferably a temperature difference of 12°C or more and 18°C or less.However, The preferred temperature difference range varies somewhat depending on the conditions for forming the CVD oxide film.

(ni) The PSG film can be selectively removed with respect to the silicon thermal oxide film within a temperature difference range of 10° C. or more and 200° C. or less.

(fv) The BPSG film can be selectively removed with respect to the silicon thermal oxide film within a temperature difference range of 10° C. or more and 150° C. or less.

(V) The PSG film can be selectively removed with respect to the silicon CVD oxide film within a temperature difference range of 15° C. or more and 200° C. or less.

(vi) The BPSG film can be selectively removed with respect to the silicon CVD oxide film within a temperature difference range of 15° C. or more and 150° C. or less.

However, the range of temperature difference may change somewhat depending on the concentration of phosphorus or boron in the film.

(Report) In the range of temperature difference of 12℃ or more and 30℃ or less,
The silicon CVD oxide film can be selectively removed with respect to the silicon natural oxide film. In this case, the best temperature range varies somewhat depending on the CVD method and the like.

(4) The PSG film can be selectively removed with respect to the silicon natural oxide film within a temperature difference range of 12° C. or more and 200° C. or less.

(Thus) The BPSG film can be selectively removed with respect to the silicon natural oxide film within a temperature difference range of 12° C. or more and 150° C. or less.

(x) In a range of temperature difference of 150℃ or more, BPS
The PSG film can be selectively removed with respect to the G film.

(xi) The silicon thermal oxide film can be selectively removed with respect to the silicon nitride film within a temperature difference range of 5° C. or more and 12° C. or less.

(xii) The silicon nitride film can be selectively removed with respect to the silicon thermal oxide film within a temperature difference range of 12° C. or more and 100° C. or less.

(xi) A silicon natural oxide film can be selectively removed with respect to a silicon nitride film within a temperature difference range of 5° C. or more and 20° C. or less.

(!-) The silicon nitride film can be selectively removed with respect to the silicon natural oxide film within a temperature difference range of 20° C. or more and 150° C. or less.

(!Ma) In the range of temperature difference of 5℃ or more and 15℃ or less,
The silicon native oxide film can be selectively removed with respect to the silicon nitride film.

(xwf) The BPSG film can be selectively removed with respect to the silicon nitride film within a temperature difference range of 5° C. or more and 150° C. or less.

(xi) PSGllI can be selectively removed from the silicon nitride film within a temperature difference range of 5° C. or more and 200″C or less.

Note that the two types of insulating films formed on the silicon layer may be formed in a stacked state on the silicon layer (in this case, the insulating film on the side to be selectively etched is formed as the upper layer), They may be formed in a planarly distributed state.

Further, in the method according to the present invention, anhydrous hydrogen fluoride (HF
A wide range of concentrations of hydrofluoric acid vapor (HF concentration of 1% or less) can be used, which is obtained by diluting 100% concentration with water (HtO) and nitrogen (N2). Furthermore, if azeotropic hydrofluoric acid (HF concentration is the same in the gas phase and liquid phase) is used as the hydrofluoric acid vapor, the one-selection etching process can be controlled more stably.

Although the above-described embodiment is an application of the present invention in the case of selectively removing a silicon native oxide film from a silicon wafer, the object to which the present invention is applied is not limited thereto.

For example, the silicon natural oxide film to be selectively removed may be a silicon natural oxide film formed on the surface of a polysilicon film or an amorphous silicon film. Furthermore, the polysilicon film and the amorphous silicon film are not limited to films formed on silicon wafers, but may be films formed on various substrates such as semiconductor wafers such as gallium and arsenic wafers. The "substrate" in the configuration of this invention is not limited to a silicon wafer, and may be, for example, a gallium arsenic wafer.

In addition, in the above embodiment, the temperature of the hydrofluoric acid vapor is kept constant,
Experiments were conducted by changing the surface temperature of the substrate to a temperature higher than that of hydrofluoric acid vapor.

Similar results can be obtained by keeping the surface temperature of the substrate constant and changing the temperature of the hydrofluoric acid vapor at a temperature lower than the surface temperature of the substrate. Furthermore, both the temperature of the hydrofluoric acid vapor and the surface temperature of the substrate may be changed. That is, in the present invention, the predetermined temperature range determined by the types of the insulating film to be selectively removed and other insulating films that are not removed is:
This refers to a predetermined range of the relative temperature difference between the mixed vapor and the substrate surface, and therefore, the present invention also includes maintaining the temperature of the mixed vapor within a predetermined temperature range lower than the surface temperature of the substrate.

〔Effect of the invention〕

Since the present invention is constructed and operates as described above, the present invention allows the surface of the substrate to be removed without extremely reducing the amount of water contained in the reaction system or without controlling the concentration of hydrogen fluoride gas. By simply controlling the temperature and the temperature of the mixed vapor supplied to the substrate surface, the desired insulating film can be selectively removed from the substrate surface, making it possible to reduce the concentration of hydrogen fluoride gas in a system with extremely low moisture content. Compared to the conventional method in which only a desired insulating film is selectively removed from the surface of a silicon layer through control, the configuration of the apparatus is simple and control of one reaction is also easy.

As described above, the present invention provides a novel method for selectively removing a native oxide film and a method for forming a contact hole before metallization in a MOS-IC manufacturing process, which can be performed relatively simply and easily. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of a silicon wafer cleaning apparatus for carrying out the method according to the present invention, and FIG.
FIG. 1 is a schematic diagram showing an example of the configuration of the gas supply unit of the apparatus shown in FIG.
FIG. 5 is a diagram showing the relationship between the surface temperature of a silicon wafer and the etching rate of a thermal oxide film, and FIG. FIG. 6 is an enlarged vertical sectional view of the main part of the apparatus shown in FIG. 5, and FIGS. FIG. 2 is a diagram showing the results of an experiment conducted. lO...outer container, 12...inner tube, 14.
...Gas/steam (hydrofluoric acid) supply port, 18...
Wafer heating chamber, 20... Steam heating chamber, 30... Ultraviolet irradiation lamp, 34.36... Temperature controller. 38...Gas supply unit. 40... Cylindrical body for wafer heating, 50... Temperature detector, W... Silicon wafer, L... Hydrofluoric acid. ■...Hydrofluoric acid vapor. Figure 2 No. 4 Figure 1) Table of wafer f] Nirayu ('C) Figure 4

Claims (1)

[Claims] 1. A mixed vapor containing at least hydrogen fluoride and water is supplied to the surface of the substrate on which at least two types of insulating films with different properties are formed, so that the desired insulating film can be replaced with other insulating films. In the method for selectively removing an insulating film from the surface of a substrate, the surface temperature of the substrate is set to a predetermined temperature range determined by the type of the insulating film, which is higher than the temperature of the mixed vapor. A method for selectively removing an insulating film, characterized in that the insulating film is retained. 2. The insulating film formed on the substrate is a silicon thermal oxide film and a silicon natural oxide film, and the predetermined temperature range is set to 10°C or more and 50°C or less, and the silicon natural oxide film is selectively used over the silicon thermal oxide film. 2. The method for selectively removing an insulating film according to claim 1, wherein the insulating film is removed from the surface of the substrate. 3. The insulating film formed on the substrate is a silicon thermal oxide film and a silicon CVD oxide film, and the temperature range for maintaining the surface temperature of the substrate higher than the temperature of the mixed vapor is 10°C or more, 30°C.
2. The method of selectively removing an insulating film according to claim 1, wherein the silicon CVD oxide film is selectively removed from the substrate surface at a temperature of 0.degree. 4. The insulating film formed on the substrate is a silicon thermal oxide film and a phosphorus-doped glass film, and the predetermined temperature range is set to 10°C or more and 200°C or less, and the phosphorus-doped glass film is selectively used with respect to the silicon thermal oxide film. 2. The method for selectively removing an insulating film according to claim 1, wherein the insulating film is removed from the surface of the substrate. 5. The insulating film formed on the substrate is a silicon thermal oxide film and a boron phosphorus doped glass film, and the predetermined temperature range is 10
2. The method of selectively removing an insulating film according to claim 1, wherein the boron phosphorus doped glass film is selectively removed from the substrate surface with respect to the silicon thermal oxide film at a temperature of at least 150°C. 6. The insulating film formed on the substrate is a silicon CVD oxide film and a phosphorus-doped glass film, and the predetermined temperature range is 15°C.
2. The method of selectively removing an insulating film according to claim 1, wherein the phosphorous-doped glass film is selectively removed from the substrate surface with respect to the silicon CVD oxide film at a temperature of 200° C. or lower. 7. The insulating film formed on the substrate is a silicon CVD oxide film and a boron phosphorus doped glass film, and the predetermined temperature range is 1.
2. The method of selectively removing an insulating film according to claim 1, wherein the boron phosphorus doped glass film is selectively removed from the substrate surface with respect to the silicon CVD oxide film at a temperature of 5° C. or higher and 150° C. or lower. 8. The insulating film formed on the substrate is a silicon natural oxide film and a silicon CVD oxide film, and the predetermined temperature range is 12
2. The method for selectively removing an insulating film according to claim 1, wherein the silicon CVD oxide film is selectively removed from the substrate surface with respect to the silicon natural oxide film at a temperature of 30°C or higher. 9. The insulating film formed on the substrate is a silicon natural oxide film and a phosphorous-doped glass film, and the predetermined temperature range is 12°C or more and 200°C or less, and the phosphorous-doped glass film is selectively used with respect to the silicon natural oxide film. 2. The method for selectively removing an insulating film according to claim 1, wherein the insulating film is removed from the surface of the substrate. 10. The insulating film formed on the substrate is a silicon natural oxide film and a boron phosphorus doped glass film, and the predetermined temperature range is 12°C or more and 150°C or less, and the boron phosphorus doped glass film is formed on the silicon natural oxide film. 2. The method of selectively removing an insulating film according to claim 1, wherein the insulating film is selectively removed from the surface of the substrate. 11. The insulating film formed on the substrate is a silicon thermal oxide film and a silicon nitride film, and the predetermined temperature range is set to 12°C or more and 100°C or less, and the silicon nitride film is selectively formed on the substrate with respect to the silicon thermal oxide film. 2. The method for selectively removing an insulating film according to claim 1, wherein the removal is performed from the surface. 12. The insulating film formed on the substrate is a silicon nitride film and a phosphorous-doped glass film, and the predetermined temperature range is 5°C or higher,
2. The method of selectively removing an insulating film according to claim 1, wherein the phosphorus-doped glass film is selectively removed from the substrate surface with respect to the silicon nitride film at a temperature of 200° C. or lower. 13. The insulating film formed on the substrate is a silicon nitride film and a boron phosphorus doped glass film, and the predetermined temperature range is 5°C.
2. The method of selectively removing an insulating film according to claim 1, wherein the boron phosphorus doped glass film is selectively removed from the substrate surface with respect to the silicon nitride film at a temperature of 150° C. or lower.