JP2001135722A - Method of manufacturing semiconductor device and sputtering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the worsening of the morphology of an alloy film surface composed mainly of aluminum, when the film is formed using high-temperature sputtering. SOLUTION: An SiO2 insulating film 4 is deposited on a semiconductor substrate 1, and contact holes 5 are selectively made through the film 4. A Ti film 6 is deposited on the internal surfaces of the holes 5 and on the insulating film 4 through sputtering and an Al-Cu alloy film 7a is deposited over the whole surface of the Ti film 6 by sputtering. Then a second Al-Cu alloy film 7b is deposited on the Al-Cu alloy film 7a so as to fill the holes 5 by sputtering, while an Ar gas heated to 500 deg.C is blown against the backside of the substrate 1. Thereafter, a third Al-Cu alloy film 7c is deposited on the second Al-Cu alloy film 7b by sputtering, while an Ar gas cooled to 0 deg.C is blown against the backside of the substrate 1. Formation of the Al-Cu alloy films 7a-7c is performed continuously in the same chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a sputtering apparatus, wherein a surface of a material mainly composed of aluminum can be formed smoothly even at a high temperature of about 500.degree. It is about.

[0002]

2. Description of the Related Art Generally, tungsten (W) is used as a material of a diffusion layer on a silicon (Si) substrate or a plug for electrically connecting a lower wiring and an upper wiring.

On the other hand, aluminum (A) which is a wiring layer material is used.
1) Or the use of an aluminum alloy as a plug material has been studied. Since aluminum (Al) or aluminum alloy has lower resistance than tungsten (W) or is the same material as the wiring, the plug filling and the formation of the wiring layer can be performed at the same time, so that the process can be simplified. There is.

Hereinafter, Al will be used as a plug material with reference to the drawings.
An example of a conventional method for manufacturing a semiconductor device using a Cu alloy will be described. 3A to 3F are cross-sectional views in the order of steps of a conventional manufacturing method in which an Al-Cu alloy plug is buried while forming an upper wiring and connected to a lower wiring.

First, as shown in FIG. 3A, a semiconductor substrate 1 made of Si on which a semiconductor element (not shown) is formed.
First insulating film 2 made of silicon oxide (SiO ₂ )
Is formed, and a lower wiring 3 is formed on the first insulating film 2.
The semiconductor element is electrically connected to the lower wiring 3 through a contact hole (not shown) opened in the first insulating film 2.

Next, as shown in FIG. 3B, a second insulating film 4 is formed on the lower wiring 3 and the first insulating film 2, and a contact hole is selectively formed in the second insulating film 4. 5 is opened.

Next, in order to improve the filling characteristics of Al, the gas contained in the second insulating film 4 is degassed in advance by heating the semiconductor substrate 1 in a vacuum. Heating is performed at a temperature higher than the subsequent film formation temperature (about 500 ° C.). Thereafter, the semiconductor substrate 1 is cooled, and then, as shown in FIG. 3C, the natural oxide film and the like on the upper surface of the lower wiring 3 exposed at the bottom of the contact hole 5 are subjected to reverse sputtering using argon (Ar). To remove. Thereafter, a titanium (Ti) film 6 serving as a metal base layer is deposited on the inner wall of the contact hole 5 and the second insulating film 4 by using a sputtering method.

Next, as shown in FIG. 3D, a first Al-Cu alloy film 7a is formed on the entire surface of the Ti film 6 by a sputtering method. At this time, in order to uniformly form the Al—Cu alloy film 7a, it is necessary to form the film at a temperature at which the reaction between Al and Ti does not occur. The substrate temperature is not controlled.

Next, as shown in FIG. 3E, a second Al-Cu alloy film 7b is formed on the first Al-Cu alloy film 7a at 500.degree.
A film is formed by a sputtering method at about a temperature. This is because the migration of Al atoms is promoted by raising the temperature, and the filling into the contact holes 5 can be realized. At this time, the first Al-Cu alloy film 7a and the second Al-Cu alloy film 7b are formed in order to prevent oxidation or gas adsorption on the surface of the first Al-Cu alloy film 7a which deteriorates the filling characteristics of Al. Films are continuously formed in the same chamber. If there is no first Al-Cu alloy film 7a, it reacts with the Ti film 6 and migration of Al atoms is prevented.

Here, FIG. 4 is a cross-sectional view schematically showing a substrate supporting portion of a conventional sputtering apparatus, and the configuration of the conventional sputtering apparatus will be described with reference to FIG. In this sputtering apparatus, the semiconductor substrate 1 is placed on a support 11 provided in a chamber 10, and the periphery of the surface of the semiconductor substrate 1 is fixed by a clamp ring 17, so that the back of the semiconductor substrate 1 is attached to the support 11. Holding. In this state, film formation is performed while introducing Ar gas from the gas introduction pipe 16.

A gas introduction chamber 12 is provided inside the support table 11, and a single gas introduction pipe 14a for introducing Ar gas, which is an inert gas whose temperature is controlled, is provided in the gas introduction chamber 12. Have been. In addition, a large number of gas blowout holes 13 for blowing Ar gas introduced into the gas introduction chamber 12 from the substrate holding surface of the support base 11 are provided on the substrate mounting surface of the support base 11.

At this time, the Ar gas is heated by the temperature control device 15a, and the heated Ar gas is introduced from the gas introduction pipe 14a into the gas introduction chamber 12 provided inside the support table 11, and the Ar gas is heated. The temperature of the semiconductor substrate 1 is controlled by blowing Ar gas onto the back surface of the semiconductor substrate 1 through the gas blowing holes 13 provided on the front surface. The gas that has heated the semiconductor substrate 1 is Ar used for sputtering.
Also used as part of gas.

In the sputtering apparatus having the above-described structure, the substrate temperature that can be controlled is only one. When the low-temperature film formation and the high-temperature film formation are performed continuously in the same chamber as described above, the low-temperature film formation is performed at the low-temperature film formation. No heating gas is introduced. Therefore, the substrate temperature at this time is not actually controlled.

Next, as shown in FIG. 3F, a titanium nitride film 8 as an antireflection layer is formed on the second Al-Cu alloy film 7b by a reactive sputtering method. The upper wiring 9 is formed by a lithography process and an etching process.

[0015] At least from the heating of the semiconductor substrate 1 for degassing to the formation of the second Al-Cu alloy film 7b are continuously performed in a vacuum. The titanium nitride film 8 may be formed after the second Al-Cu alloy film 7b is formed and then exposed to the air once. However, in order to improve reliability, the second Al-Cu alloy film is used. It is desirable to perform the process continuously in a vacuum after the film formation of 7b.

[0016]

As described above, in order to fill the inside of the contact hole with a material mainly composed of Al, the substrate must be heated to a high temperature of about 500 ° C. to form a film. However, when the film is formed at a high temperature, the crystal grains in the film grow larger as the film is deposited, and the surface of the adjacent crystal grains is formed asperities, thereby deteriorating the surface morphology. In addition, the surface morphology means flatness in the surface shape, and poor means large irregularities.

Although the film thickness required to fill the contact hole 5 is about the hole diameter, the thickness of the wiring layer is often larger than the film thickness. As the film thickness increases, crystal grains grow and the surface morphology deteriorates. Deterioration of surface morphology is
A pattern formation defect is caused in a subsequent lithography process, which becomes more remarkable as miniaturization progresses.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a method of manufacturing a semiconductor device and a sputtering apparatus capable of preventing deterioration of surface morphology even when a film is formed by a sputtering method at a high temperature. The purpose is to provide.

[0019]

According to a method of manufacturing a semiconductor device according to the present invention, a contact hole is opened in an interlayer insulating film of a substrate having an interlayer insulating film on a lower wiring or a diffusion layer region, and aluminum is formed by sputtering. This is a method of manufacturing a semiconductor device in which a metal wiring layer as a main material is formed on an interlayer insulating film while being buried in a contact hole, and then the metal wiring layer is etched to form an upper wiring. Step 2 is performed sequentially without exposing to air.

In the first wiring layer forming step, a high temperature condition not lower than the temperature at which aluminum particles can flow on the interlayer insulating film and not higher than the melting point of the material mainly containing aluminum is set so as to fill the contact holes. A first wiring layer made of a material mainly containing aluminum and constituting a metal wiring layer is formed while heating the substrate. In the second wiring layer forming step, the substrate is placed on the first wiring layer under a low temperature condition lower than the high temperature condition and at a low temperature condition that does not cause growth of aluminum alloy crystal grains in the first wiring layer. After cooling, a second wiring layer made of a material mainly containing aluminum and constituting a metal wiring layer is formed.

Before the first wiring layer forming step, a metal base layer forming step of forming a metal base layer constituting a metal wiring layer on the inner wall of the contact hole and on the interlayer insulating film is provided. On the entire surface, the metal wiring layer is made of a material mainly composed of aluminum while cooling the substrate to a low temperature condition not higher than the temperature at which the reaction between the metal underlayer and the aluminum occurs and the temperature at which the flow of the aluminum particles occurs. A third wiring layer forming step of forming a third wiring layer may be included. Further, an anti-reflection layer forming step of forming an anti-reflection layer on the second wiring layer may be further included. The material mainly containing aluminum is, for example, an aluminum-copper alloy.

In the above, it is necessary to continuously perform the steps up to the formation of the second wiring layer in a vacuum. The anti-reflection layer may be formed after exposing to the air once after the formation of the second wiring layer. However, in order to improve reliability, the anti-reflection layer is continuously formed in a vacuum after the formation of the second wiring layer. It is desirable to carry out.

According to the method of manufacturing a semiconductor device, the contact hole is filled with a material mainly containing aluminum by film formation at a high temperature, and then the film mainly containing aluminum accompanying the growth of crystal grains is cooled by cooling the substrate. By suppressing surface unevenness and forming a film at a low temperature on a surface having unevenness, the unevenness of the film surface can be reduced.

The sputtering apparatus according to the present invention is different from a chamber, a support provided in the chamber for holding the back surface of the substrate, a gas introduction chamber provided inside the support, and a gas introduction chamber. At least two gas introduction pipes for introducing an inert gas of which temperature is controlled to a temperature, and an inert gas provided on the substrate mounting surface of the support and introduced into the gas introduction chamber for holding the inert gas on the substrate holding surface of the support. And a gas blow-out hole for blowing out the gas. Then, an inert gas whose temperature is controlled to a different temperature is introduced from at least two gas introducing pipes into the gas introducing chamber, and the inert gas whose temperature is controlled to a different temperature is selectively supplied to the back surface of the substrate through the gas blowing holes. To control the temperature of the substrate.

According to this sputtering apparatus, film formation at different temperatures can be performed continuously in the same chamber. As a result, film formation at different temperatures can be easily performed.

[0026]

Embodiments of the present invention will be described with reference to the drawings.

FIGS. 1A to 1G are sectional views in the order of steps of a method of manufacturing a semiconductor device according to an embodiment of the present invention. Hereinafter, an embodiment of a method of manufacturing a semiconductor device will be described with reference to FIG.

First, as shown in FIG. 1A, a semiconductor substrate 1 made of Si on which a semiconductor element (not shown) is formed.
A first insulating film 2 made of silicon oxide (SiO ₂ ) is formed on the first insulating film 2, and a lower wiring 3 (TiN
/ AlCu / Ti = 30nm / 600nm / 70nm)
To form The semiconductor element is electrically connected to the lower wiring 3 through a contact hole (not shown) opened in the first insulating film 2.

Next, as shown in FIG. 1B, a second insulating film 4 made of silicon oxide (SiO ₂ ) having a thickness of 2.7 μm is formed on the first insulating film 2 and the lower wiring 3. After the formation, planarization is performed so that the film thickness on the lower wiring 3 is 1 μm, and a contact hole 5 having a diameter of 0.4 μm is selectively opened in the second insulating film 4.

Next, in the degassing chamber, the semiconductor substrate 1 is degassed by heating the semiconductor substrate 1 in a vacuum at 510 ° C. for 180 seconds, and then the semiconductor substrate 1 is cooled to room temperature. Next, as shown in FIG. 1C, a native oxide film or the like on the upper surface of the lower wiring 3 exposed at the bottom of the contact hole 5 is removed by reverse sputtering with argon (Ar), and then sputtering is performed. Then, a titanium (Ti) film 6 as a metal base layer is deposited to a thickness of 20 nm on the inner wall of the contact hole 5 and on the second insulating film 4.

Next, prior to the formation of an Al—Cu alloy film, the sputtering apparatus is explained with reference to the cross-sectional view schematically showing the substrate support of the sputtering apparatus according to the embodiment of the present invention shown in FIG. Will be described. In this sputtering apparatus, the semiconductor substrate 1 is placed on a support 11 provided in a chamber 10, and the periphery of the surface of the semiconductor substrate 1 is fixed by a clamp ring 17, so that the back of the semiconductor substrate 1 is attached to the support 11. Holding. In this state, film formation is performed while introducing Ar gas from the gas introduction pipe 16.

A gas introduction chamber 12 is provided inside the support table 11, and at least two gases for introducing Ar gas, which is an inert gas whose temperature is controlled to different temperatures, into the gas introduction chamber 12. Introducing pipes 14a and 14b are provided. In addition, a large number of gas blowout holes 13 for blowing Ar gas introduced into the gas introduction chamber 12 from the substrate holding surface of the support base 11 are provided on the substrate mounting surface of the support base 11.

At this time, the Ar gas is heated or cooled by the temperature control devices 15a and 15b, and is supplied to the gas introduction chamber 12 provided inside the support base 11 by the gas introduction pipes 14a and 14a.
4b, heated or cooled Ar gas, which was temperature-controlled to different temperatures, was introduced, respectively.
The temperature of the semiconductor substrate 1 is controlled by selectively blowing heated or cooled Ar gas to the back surface of the semiconductor substrate 1 through the gas blowing holes 13 provided on the front surface of the semiconductor substrate 1. The gas that has heated the semiconductor substrate 1 is also used as a part of Ar gas used for sputtering.

Next, as shown in FIG. 1D, a first Al—Cu alloy film 7a as a third wiring layer is deposited to a thickness of 50 nm on the entire surface of the Ti film 6 by a sputtering method. At this time, Ar gas cooled to 0 ° C. by the temperature control device 15b is introduced from the gas introduction pipe 14b, and the semiconductor substrate 1 is cooled by spraying the gas on the back surface of the substrate, and then a film is formed. The introduced amount of the cooled Ar gas is 15 sccm, and this Ar gas is introduced into the chamber and used as a sputtering gas. The introduction amount of Ar gas from the gas introduction pipe 16 is 35 sccm, and the Ar gas pressure is 2 mTorr.
And the deposition rate is 1.0 μm / min.

The semiconductor substrate 1 is continuously cooled during the film formation.

Here, the gas temperature range and the substrate temperature range will be described. The substrate temperature is desirably about 0 to 100 ° C. (0.3 to 0.4 when the melting point is T _M).
The required film quality can be obtained in this temperature range below T _M ). The gas only needs to be at a temperature capable of achieving this, and it is necessary that the gas be at least the substrate temperature or less. Its value is, for example, about -100 to 0 ° C.

The case where the semiconductor substrate 1 is not cooled during the formation of the first Al-Cu alloy film 7a (left at room temperature as in the conventional example) is as follows. That is, the substrate may be at room temperature, but the temperature of the substrate may be increased because the degassing process and the film forming process are performed in the previous step. In that case, there is a case where it is not effective if left at room temperature.

Next, as shown in FIG. 1E, a second Al-Cu alloy as a first wiring layer is formed on the first Al-Cu alloy film 7a while burying the inside of the contact hole 5. A film 7b is deposited to a thickness of 400 nm by a sputtering method. At this time, an Ar gas heated to 500 ° C. by the temperature control device 15a is introduced from the gas introduction pipe 14a and sprayed onto the back surface of the substrate to heat the semiconductor substrate 1 to form a film. The introduced amount of the heated Ar gas is 15 sc
cm, and this Ar gas is introduced into the chamber and used also as a sputtering gas. The introduction amount of Ar gas from the gas introduction pipe 16 is 35 sccm, and the Ar gas pressure is 2 m.
Torr, and the deposition rate is 0.1 μm / min.

Here, the temperature range of the Ar gas and the substrate will be described. The substrate temperature needs to be about 470-570 ° C. The gas may be at any temperature that can achieve this. Considering the heating efficiency, it is necessary that the temperature be at least the substrate temperature (about 500 to 600 ° C.).

Next, as shown in FIG. 1F, a third Al-Cu alloy film 7c as a second wiring layer is formed on the entire surface of the second Al-Cu alloy film 7b by a sputtering method. Thus, a film thickness of 150 nm is deposited. At this time, the temperature control device 15
b to Ar gas cooled to 0 ° C.
The semiconductor substrate 1 is cooled by spraying it onto the back surface of the substrate, and then a film is formed. The introduced amount of the cooled Ar gas is 15 sccm, and this Ar gas is introduced into the chamber and used as a sputtering gas. The introduction amount of Ar gas from the gas introduction pipe 16 was 35 sccm, and A
The r gas pressure is 2 mTorr and the deposition rate is 1.0 μm
/ Min. From the first Al-Cu alloy film 7a to the third A
Film formation up to the l-Cu alloy film 7c is continuously performed in the same chamber. It should be noted that the metal wiring layer is composed of the Ti film 6 and the first film.
Al-Cu alloy film 7a and second Al-Cu alloy film 7b
And the third Al-Cu alloy film 7c. In addition,
The semiconductor substrate 1 is cooled during the film formation.

It should be noted that in each of the above steps, it is necessary to continuously perform the steps in a vacuum because the first Al—Cu alloy film 7 a
To the formation of the third Al-Cu alloy film 7c must be continuously performed at least in a vacuum. It is desirable that the formation of the third Al-Cu alloy film 7c from degassing be performed continuously in a vacuum.

Next, as shown in FIG. 1 (g), Ti is formed as an anti-reflection layer on the entire surface of the third Al-Cu alloy film 7c.
After the N film 8 is deposited by the reactive sputtering method, a mask pattern (not shown) is formed by using photolithography, and thereafter, the Ti film 6, the first, second and third masks are formed by using the mask pattern. Al-Cu alloy films 7a, 7
b, 7c and the TiN film 8 are etched and subjected to predetermined patterning to form an upper wiring 9
To form

The TiN film 8 is deposited by the reactive sputtering method, for example, by introducing an Ar gas at an amount of 30 sccm, an N ₂ gas at an amount of 35 sccm, and an Ar + N ₂ gas pressure of 4 mTorr.
r, the film formation speed is 100 nm / min.

The TiN film (anti-reflection layer) 8 is formed by the reactive sputtering method.
After the film formation of c, it is desirable from the viewpoint of reliability that the film formation is performed without exposure to the air. In the present invention, the formation of the second Al—Cu alloy film 7b must be continuously performed in a vacuum, but the subsequent formation of the TiN film (antireflection layer) 8 is performed after exposure to air. May be.

In the present embodiment, the first to third embodiments
Although the film thicknesses of the Al—Cu alloy films 7a, 7b, and 7c and the temperature during high-temperature sputtering are set as described above, they can be appropriately changed according to the thickness of the wiring layer and the size of the contact hole 5.

In the method of manufacturing a semiconductor device as described above, after the third Al-Cu alloy film 7c is formed, the Al-Cu alloy film 7c is formed using an atomic force microscope (AFM).
When the surface roughness was evaluated, the surface roughness was 20n on average.
m.

As a comparative example, the third Al—Cu alloy film 7c was not formed, and the second Al—Cu alloy film was
After depositing 00 nm, the surface roughness was evaluated, and the surface irregularities were 50 nm on average.

As described above, by using the method for manufacturing a semiconductor device and the sputtering apparatus according to the present embodiment, unevenness on the surface can be suppressed even when a film is formed by a high-temperature sputtering method.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various changes can be made without departing from the gist of the present invention. Needless to say. For example, a film without the Ti film 7 and the first Al-Cu alloy film 7a is also included in the present invention.

The materials mainly composed of aluminum include Al-Cu alloy, Al-Si alloy, Al-S
An i-Cu alloy is conceivable.

[0051]

As described above, according to the method for manufacturing a semiconductor device and the sputtering apparatus according to the present invention,
Even when the metal wiring layer is formed using a high-temperature sputtering method, deterioration of surface morphology can be suppressed.

[Brief description of the drawings]

FIGS. 1A to 1G are cross-sectional views in the order of steps showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a substrate support of the sputtering apparatus according to the embodiment of the present invention.

FIGS. 3A to 3F are cross-sectional views in the order of steps showing a method for manufacturing a conventional semiconductor device.

FIG. 4 is a cross-sectional view schematically showing a substrate support of a conventional sputtering apparatus.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 first insulating film 3 lower wiring 4 second insulating film 5 contact hole 6 Ti film (metal underlayer) 7a first Al-Cu alloy film (third wiring layer) 7b second Al -Cu alloy film (first wiring layer) 7c Third Al-Cu alloy film (second wiring layer) 8 Titanium nitride film (anti-reflection layer) 9 Upper wiring 10 Chamber 11 Support base 12 Gas introduction chamber 13 Gas Blow-out hole 14a Gas introduction pipe 14b Gas introduction pipe 15a Temperature controller 15b Temperature controller 16 Gas introduction pipe 17 Clamp ring

Front page of the continued F-term (reference) 4M104 BB14 DD06 DD16 DD23 DD32 DD37 DD39 DD41 DD42 FF13 FF17 FF22 HH12 5F033 HH09 HH33 JJ09 JJ18 KK09 KK18 KK33 MM08 NN06 PP15 PP16 PP33 QQ03 QQ37 QQ75 QQ85 QQ88 QQ92 QQ98 RR04 WW03 XX01

Claims (5)

[Claims] 1. A contact hole is opened in said interlayer insulating film of a substrate having an interlayer insulating film on a lower wiring or a diffusion layer region, and a metal wiring layer mainly composed of aluminum is formed on said interlayer insulating film by a sputtering method. A method of manufacturing a semiconductor device in which an upper layer wiring is formed by etching the metal wiring layer after being buried in the contact hole while forming a film, wherein the inside of the contact hole is buried on the interlayer insulating film. The first metal wiring layer made of a material mainly composed of aluminum while heating the substrate to a high temperature condition not lower than the temperature at which the flow of aluminum particles can occur and not higher than the melting point of the material mainly composed of aluminum. A first wiring layer forming step of forming a wiring layer; and forming the first wiring layer on the first wiring layer at a temperature lower than the high temperature condition. After cooling the substrate to a low temperature condition that does not cause growth of aluminum alloy crystal grains in the wiring layer, a second wiring layer made of a material mainly containing aluminum and constituting the metal wiring layer is formed. A method for manufacturing a semiconductor device, comprising: a second wiring layer forming step, wherein the first wiring layer forming step and the second wiring layer forming step are sequentially performed without exposing to air. 2. A metal underlayer forming step of forming a metal underlayer constituting a metal wiring layer on an inner wall of a contact hole and on an interlayer insulating film before the first wiring layer forming step; And cooling the substrate to a low temperature condition not higher than the temperature at which the reaction between the metal underlayer and the aluminum occurs and the temperature at which the flow of the aluminum particles occurs. A third wiring layer forming step of forming a third wiring layer forming a layer, wherein the metal underlayer forming step and the third wiring layer forming step are performed.
2. The method of manufacturing a semiconductor device according to claim 1, wherein the step of forming a wiring layer is sequentially performed without exposing to air, and the step of forming a first wiring layer is started without exposing to air. 3. The method according to claim 1, further comprising the step of forming an anti-reflection layer on the second wiring layer. 4. The method according to claim 1, wherein the material mainly composed of aluminum is an aluminum-copper alloy.
The manufacturing method of the semiconductor device described in the above. 5. A chamber, a support provided in the chamber for holding a back surface of a substrate, a gas introduction chamber provided inside the support, and a temperature controlled to a different temperature in the gas introduction chamber. At least two gas introduction pipes for introducing the inert gas, and the inert gas provided to the substrate mounting surface of the support table and introduced into the gas introduction chamber from the substrate holding surface of the support table. A gas blowout hole for blowing out, and introducing an inert gas whose temperature is controlled to a different temperature into the gas introduction chamber from the at least two gas introduction pipes, respectively, to the back surface of the substrate through the gas blowout hole. A sputtering apparatus, wherein the temperature of the substrate is controlled by selectively blowing an inert gas whose temperature is controlled to a temperature.