JPH1144619A - Method and apparatus for evaluating airborne impurities - Google Patents

Abstract

(57) Abstract: An object of the present invention is to analyze and control impurities contained in the environment of a manufacturing process to prevent a reduction in the manufacturing yield and reliability of a semiconductor device due to these impurities. Abstract: A wafer flowing in a semiconductor device manufacturing process is extracted, and air is directly brought into contact with the surface of the wafer to form air impurities which occur in the process and cause a problem in process yield. The air-impurities are evaluated by adsorbing and collecting the treated surface and controlling the analysis. Also, as an adsorption surface provided on the wafer surface, several types of surface processing layers and adsorption films with high detection sensitivity for specific impurities, or a combination thereof are formed in a separate process,
Using the sensor as a sensor, an air impurity evaluation method and an apparatus capable of identifying air impurity impurities widely occurring in a manufacturing environment and searching for a source of the impurities are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for evaluating airborne impurities, and more particularly to a method for analyzing and controlling airborne impurities in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art With the progress of semiconductor devices, contamination by airborne impurities adsorbed on a wafer surface from an environmental atmosphere in a manufacturing process thereof has been a problem. For example organic substances contained in the manufacturing environment, i.e. an acidic gas such as SO _x, NO _x,
Attention has been paid to the fact that impurities such as a basic gas such as ammonia adversely affect the yield of a manufacturing process and the characteristics of a semiconductor device.

[0003] Contamination by organic substances causes deterioration of the withstand voltage characteristics of the oxide film, and also causes haze (cloudiness) of the wafer surface and the thin film formed on the wafer. Therefore, specifying and controlling these airborne impurities is indispensable for securing the yield and reliability of the manufacturing process of the semiconductor device. For this reason, a technique for evaluating airborne impurities contained in a manufacturing environment has been indispensable.

[0004] Conventionally, methods for evaluating airborne impurities include a method of directly analyzing the atmosphere, which is an environmental atmosphere, with a measuring instrument,
2. Description of the Related Art There is known a method of once passing the air through a solid adsorbent or a liquid collecting liquid to collect a target impurity and analyzing the impurity by a measuring instrument.

However, impurities contained in the air and adsorbed on the wafer have a selectivity that the adsorption rate differs depending on the type, and have a dependency on the adsorbed surface of the base.
For example, compounds having a large molecular weight among airborne impurities, C
Phenomena such as a compound having an ＯO bond are easily adsorbed, and particularly when the adsorption surface is an oxide film surface.

Next, a conventional technique for evaluating impurities in a manufacturing environment will be described more specifically. In general, a method of counting the number of fine particles per unit volume contained in the atmosphere using a dust counter, or a bare wafer 10 whose surface is simply mirror-polished as shown in FIG. There is a method in which the particles are left on the support table 11 in a manufacturing environment for a certain period of time to count the number of fine particles adhering on the bare wafer. However, this method cannot obtain information on gaseous impurities contained in the manufacturing environment.

In particular, in recent years, the influence of an organic gas having a large molecular weight has been attracting attention in relation to the breakdown voltage of a semiconductor device. However, in the conventional method of directly analyzing the atmosphere as described above, a low concentration that occupies most of the impurity gas is used. There is a problem that the measurement result is masked by the impurities having a high molecular weight, so that an impurity gas having a high molecular weight cannot be detected.

[0008] In the method of once collecting airborne impurities contained in the production environment into a solid adsorbent or a collecting liquid and analyzing and evaluating the impurities, the type of the impurities to be collected depends on the type of the adsorbing agent and the collecting liquid. Because of the differences, the impurities to be analyzed are limited,
There is a problem that it becomes difficult to specify and control the target impurities.

In the manufacturing process of a semiconductor device, it is important to analyze and evaluate impurities adsorbed on a processed surface of a wafer in a manufacturing process which is actually processed in a manufacturing environment. Therefore, there has been no effective air impurity evaluation method and apparatus for coping with this.

[0010]

As described above, the conventional method and apparatus for evaluating airborne impurities contaminate the processing surface of a wafer during a manufacturing process, which greatly affects the yield and reliability of a semiconductor device. In addition, there is a problem that it is not possible to effectively analyze an organic substance gas having a large molecular weight.

The present invention has been made in order to solve the above-mentioned problems. The present invention is actually applied to a semiconductor device manufacturing process, a wafer processed in the process is extracted, and the processing surface is forcibly brought into direct contact with the atmosphere. The present invention aims to provide a method and an apparatus for evaluating airborne impurities by adsorbing and collecting on the processing surface and analyzing airborne impurities which occur in the process and particularly pose a problem in the process yield, on the processing surface. And

In the present invention, a substrate having excellent impurity gas adsorption characteristics is separately formed by using a specific surface treatment layer, a specific adsorption film, or a combination of both as an adsorption surface provided on the substrate surface. Using this as a sensor, the purpose is to evaluate airborne impurities that occur widely in the manufacturing environment.

[0013]

According to a method for evaluating airborne impurities of the present invention, an adsorption surface provided on a substrate surface is brought into contact with the atmosphere, whereby impurities contained in the air are adsorbed on the adsorption surface. By measuring the adsorbed impurities, the impurities contained in the air are evaluated.

The substrate is a semiconductor wafer extracted in a wafer processing step of a semiconductor device, and at least an insulating film is formed on a surface of the semiconductor wafer.

Preferably, the insulating film is a silicon oxide film,
It comprises a polycrystalline silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, a titanium oxide film, and a combination thereof.

As described above, by using the insulating film extracted in the actual wafer processing step and formed in this step as an adsorption film for the impurity gas which is a problem in this step, the impurity gas which becomes a problem in each step can be eliminated. Can be identified.

Further, the suction surface is one of an adsorption film formed on the substrate, a processed layer on the substrate surface, and an adsorption film formed on the processed layer on the substrate surface. By using a specific surface processing layer, a specific adsorption film, or a combination of both as the adsorption surface provided on the substrate surface in this way, a material having excellent impurity gas adsorption characteristics is formed, and this is widely used as a sensor. Aerial impurities generated during the manufacturing process can be evaluated.

The apparatus for evaluating airborne impurities according to the present invention comprises an air inlet through which air is introduced from above, a substrate provided with a surface for absorbing airborne impurities, and a substrate mounting mechanism on which the substrate is mounted horizontally. And an exhaust port for exhausting air from the lower part of the substrate mounting mechanism.

Preferably, the chamber has rotational symmetry with respect to a central axis, the inlet and the outlet have a circular shape, and the centers of the inlet and the outlet coincide with the center axis of the chamber. And the substrate is placed on the substrate placing mechanism such that the center of the substrate coincides with the central axis of the chamber.

Further, the air impurity evaluation device of the present invention is arranged such that the intake port is axially symmetric with respect to a central axis,
The suction port is formed of a plurality of suction ports that are larger as being closer to the central axis, the substrate is placed horizontally on a substrate placing mechanism, and the substrate is placed so that the center of the substrate coincides with the central axis of the chamber. It is characterized by having been done.

[0021] Preferably, the substrate mounting mechanism supports the substrate from below by point contact. Preferably, the chamber has a structure capable of being vertically separated along an outer periphery thereof.

Further, the apparatus for evaluating airborne impurities according to the present invention comprises a substrate having an adsorption surface for atmospheric impurities, a vacuum chuck for suction-fixing the substrate, a long side parallel to the adsorption surface, and a short side corresponding to the adsorption surface. An intake port having a rectangular cross-section that is vertical and that introduces air along the adsorption surface from one end of the adsorption surface, and a position opposite to the intake port, the air being introduced from the other end of the adsorption surface. And an exhaust port for exhausting air.
Preferably, the apparatus for evaluating airborne impurities according to the present invention includes a mechanism for controlling the temperature of the adsorption surface.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1A and 1B are a cross-sectional view and a top view, respectively, of an aerial impurity evaluation device according to a first embodiment of the present invention. FIG. 1A shows FIG.
The AA cross section of (b) is shown. The apparatus for evaluating impurities in the air includes a semiconductor substrate 1, a substrate mounting mechanism 2, a chamber 3, an atmosphere 4 to be evaluated (hereinafter simply referred to as atmosphere) constituting an environment of a manufacturing process, and a pump for sucking the atmosphere 4. 5 is comprised.

As shown in FIG. 1 (a), the chamber 3 has a structure capable of being separated into an upper part and a lower part, and a seal 6 which does not generate impurity gas is provided between the upper and lower chambers. Sealed. This portion does not necessarily need to be completely sealed as long as no impurity gas is generated, for example, as in a rubbing provided between the upper and lower chambers.

The upper and lower chambers 3 are respectively provided with an intake port 7 and an exhaust port 8 for suctioning or exhausting the atmosphere at the center. The upper intake port 7 is open to the atmosphere, and the lower exhaust port 8 is connected to the suction pump 5.

The upper and lower chambers are each formed of aluminum, aluminum alloy, stainless steel, quartz, or the like. The suction pump 5 has a maximum of 30 (l / mi)
A pump having a pumping speed of n) was used. Silicon rubber or fluorine rubber that does not generate impurity gas is used for the seal.

First, the upper chamber 3 is opened, and the substrate (here, silicon wafer) 1 in the manufacturing process for adsorbing the impurity gas is extracted, and the processing surface formed in the manufacturing process is set as the adsorbing surface 1a, and the upper surface is lifted. And chamber 3
The upper chamber 3 is closed via a seal 6 on the substrate mounting mechanism 2 provided at the lower part of the substrate.

Next, the suction pump 5 connected to the exhaust port 8 of the lower chamber is operated to suck the atmosphere 4 from the intake port 7 into the chamber 3 for a predetermined time according to the impurity concentration contained in the atmosphere 4.

The apparatus for evaluating airborne impurities described above is shown in FIG.
As shown in the top view of (b), the substrate mounting mechanism 2, the bell jar 3, the intake port 7, and the exhaust port 8 are arranged so as to be rotationally symmetric with respect to a vertical center axis, respectively. Are placed on the substrate placing mechanism 2 so as to coincide with the central axis, and the suction surface 1a is horizontal. FIG. 1
In (a), the suction surface 1a is formed only on one side of the substrate 1, but may be formed on both sides.

When the substrate 1 is made of a substantially circular silicon wafer as shown in FIG. 1B, the bell jar 3 and the intake port 7 and the exhaust port 8 are rotated so as to have rotational symmetry about the central axis. For example, as shown by an arrow in FIG. 1A, the atmosphere 4 flowing inside the bell jar 3 is in a laminar flow state and flows along the adsorption surface 1a, so that the impurity gas contained in the air can be efficiently removed from the adsorption surface. 1a.

Here, the substrate mounting mechanism 2 mounts the substrate 1 by, for example, three-point contact so as not to hinder the flow of the atmosphere 4 sucked by the pump 5. The mounting and demounting of the substrate 1 is made extremely easy. At this time, a damper (not shown) for vibration isolation is provided between the pump 5 and the exhaust port 8 so that the substrate 1 is not displaced by the vibration of the pump 5. The structure of the substrate mounting mechanism 2 does not necessarily have to be a three-point contact as long as it can be easily attached and detached and a laminar air flow can be obtained.

In this way, the atmosphere 4 to be evaluated is introduced into the chamber 3 through the upper intake port 7, and the above-mentioned manufacturing process is started immediately above the adsorption surface 1a of the substrate 1 processed in the manufacturing process to be evaluated. When the atmosphere 4 constituting the environment is blown, the atmosphere 4 and the adsorption surface 1a are in efficient contact with each other, and the impurity gas contained in the atmosphere 4 selectively removes the adsorption surface 1a of the wafer 1.
Is adsorbed.

At this time, the type of the impurity gas adsorbed on the adsorption surface 1a differs mainly depending on the type of the insulating film constituting the adsorption surface and the combination thereof. It can be specified for each processing step for forming. For example, as an insulating film exhibiting excellent adsorption to impurity gases, a silicon oxide film, a polycrystalline silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, a titanium oxide film, or a film combining these The impurity gas which is particularly problematic in the step of forming the insulating film can be specified by using the above method.

The atmosphere 4 is sucked for a certain time, and the suction surface 1 of the substrate 1 is sucked.
After the adsorption and collection at a, the pump 5 is stopped, the upper part of the chamber 3 is released, the substrate 1 made of a silicon wafer is taken out, and the type of adsorbate is identified and the amount is measured using a measuring device.

As an impurity measuring device, organic substances are desorbed and extracted by a wafer heating desorption method or a wafer solvent extraction method and then analyzed using a gas chromatograph, or the desorbed and extracted organic substances are analyzed by gas chromatography and mass analysis. The analysis was performed in combination with an analyzer. In addition, inorganic substances such as acidic gas and basic gas were analyzed using an ion chromatograph after extracting the wafer with pure water. Furthermore, for water-soluble organic substances, TOC analyzer (total organic carbon analyzer; Total Orga
nic Carbon analyzer). For moisture and halogen gas, an APMS system (atmospheric ionization mass spectrometer; Atmosp
heric Pressure Ionization Mass Spectrometer).

Next, a second embodiment of the present invention will be described with reference to FIG. 2 (a) and 2 (b) are a cross-sectional view and a top view, respectively, of an airborne impurity evaluation device according to a second embodiment of the present invention. FIG. 2 (a) shows A in FIG. 2 (b).
-A cross section is shown. This air impurity evaluation apparatus differs from the air impurity evaluation apparatus of the first embodiment only in the structure of the upper chamber 3.

That is, as shown in FIG. 2, a plurality of intake ports 7 for introducing the atmosphere 4 to be evaluated into the chamber are formed on almost the entire surface of the upper chamber 3.
The other parts are the same as those of the air impurity evaluation device of the first embodiment, and thus the description is omitted.

The apparatus is configured so as to be symmetrical with respect to the central axis, and the plurality of intake ports 7 are also arranged so as to be symmetrical with respect to the central axis. In the example shown in FIG.
The plurality of suction ports 7 are all circular, and the diameter is larger as the position is closer to the center, and is reduced toward the periphery.
By increasing the suction amount of the atmosphere 4 in the central portion in this manner, the flow of the atmosphere 4 on the adsorption surface 1a of the substrate 1 can be made substantially laminar, and the impurity gas contained in the atmosphere 4 can be removed from the adsorption surface 1a. Can be adsorbed efficiently.

Next, a third embodiment of the present invention will be described with reference to FIG. FIGS. 3A and 3B are a cross-sectional view and a bird's-eye view of an airborne impurity evaluation device according to a third embodiment of the present invention, respectively. In the third embodiment, a structure in which the atmosphere 4 flows in parallel along the suction surface 1a of the substrate 1 is shown.

The apparatus for evaluating impurities in the air has a semiconductor substrate 1
From the suction surface 1 a, the chamber 3, the atmosphere 4 to be evaluated, the pump 5 for sucking the atmosphere 4, the rectangular intake port 7 and the exhaust port 8, and the vacuum chuck 9 for fixing the semiconductor substrate 1. Be composed. The semiconductor substrate 1 can be cooled by the temperature control unit also serving as the vacuum chuck 9, and the suction efficiency of the suction surface 1a can be increased.

FIG. 3B is a sectional view taken along the line AA of the bird's-eye view of FIG.
This is shown in FIG. The semiconductor substrate 1 is inserted into the flat chamber 3 from the air inlet 7 and is fixed by the vacuum chuck 9 so that the suction surface 1a is oriented so that the atmosphere 4 in the chamber flows.

If the temperature control unit included in the vacuum chuck 9 adjusts the temperature to a lower temperature so that the adsorption of airborne impurities on the adsorption surface 1a is maximized, and the pump 4 sucks the atmosphere 4 for a certain time, The impurities contained in the atmosphere 4 are adsorbed on the adsorption surface 1a. The pump 5 is stopped, the vacuum chuck 9 is released, the wafer is taken out, and the adsorbed impurities are analyzed in the same manner as described in the first embodiment.

The features of the air impurity evaluation apparatus shown in FIG.
The handling is easier than that shown in FIGS. 1 and 2, and in particular, if the exhaust port 8 has a flexible structure, the air to be evaluated can be introduced from an arbitrary angle. Impurities and the like generated in a specific portion of the constituent atmosphere can be analyzed and evaluated. At this time, the suction surface 1a
Is maintained in a laminar flow state regardless of the angle of the intake port 7.

As described above, in the apparatus for evaluating airborne impurities shown in FIG. 3, the adsorption surface 1a is always used as the processing surface in the specific process.
In addition to the analysis and evaluation for each step, such as analyzing impurities generated in the specific step, the adsorption surface 1a has a high adsorption rate for a specific impurity and is used as a sensor. It can also be used for the purpose of searching for the source of specific airborne impurities generated in a wide range of manufacturing process environments.

At this time, it is desirable to increase the surface area of the adsorption surface 1a serving as a sensor. For example, the surface of a silicon wafer is made porous and oxidized to increase the amount of adsorbed impurity gas, By forming a trench along the direction in which the atmosphere 4 flows on the surface of the substrate 1 and covering the trench with, for example, an adsorption film such as an oxide film, the effective surface area of the adsorption surface 1a is increased several times. Thus, the amount of adsorption of the impurity gas can be increased. As described above, the structure of the adsorption surface used as the impurity sensor is different from the processing surface of the semiconductor substrate in the actual manufacturing process. However, if sensors corresponding to several kinds of target impurities are prepared, the manufacturing process environment can be improved. And useful information on the source of the impurities generated in the process.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, impurities in the air in an operating clean room are captured using the air impurity evaluation apparatus according to the first embodiment of the present invention and a wafer in an actual manufacturing process. The results collected and analyzed will be described.

The manufacturing process to be evaluated here is a process for forming a floating gate of polycrystalline silicon of a nonvolatile semiconductor memory device. An oxide film (SiO ₂ ) formed on the polycrystalline silicon by thermal oxidation is adsorbed. Used as 1a. The atmosphere 4 to be evaluated was collected from the vicinity of the thermal oxidation furnace.

FIG. 4 shows the relationship between the amount of airborne organic impurities (C ₈ H ₁₆ ) adsorbed on the wafer and the oxide film breakdown voltage measured by the airborne impurity evaluation apparatus according to the first embodiment of the present invention.
It can be seen that as the amount of adsorbed C ₈ H ₁₆ increases, the yield rate of the oxide film breakdown voltage rapidly decreases.

The results of analysis by gas chromatography of the atmospheric impurities collected by the method of the present invention and the atmospheric impurities collected by the conventional air impurity evaluation method in which a bare wafer was simply left in a clean room are shown. 5 (a) and 5 (b), respectively.

As shown in FIG. 5A, when the air impurity is selectively adsorbed on the wafer in the manufacturing process using the air impurity evaluation apparatus of the present invention, strong C ₈ H ₁₆
It is understood that the influence on the oxide film breakdown voltage is clearly captured. On the other hand, as shown in FIG. 5B, when the atmosphere is analyzed by the conventional method, C ₈ H ₁₆
Almost no adsorbed impurities are detected, and the size of the peak corresponding to C ₈ H ₁₆ is 1/10 or less. Therefore, it has been confirmed that it is impossible to specify the cause of the deterioration of the breakdown voltage of the oxide film due to impurities in the atmosphere by the conventional method.

FIG. 6 shows the relationship between the amount of impurities adsorbed on the wafer and the time (days) required for adsorption. With respect to impurities composed of C ₈ H ₁₆ , it took 24 hours or more to collect the atmosphere 4 in order to obtain an impurity amount that can be analyzed by the conventional method. However, according to the apparatus and method of the present invention, about 2 hours were required. It was found that the same amount of impurities was collected in time, and the sensitivity was significantly improved. In this way, by detecting and removing harmful impurities under conditions close to in-situ observation, the occurrence of process defects could be controlled to a minimum.

The present invention is not limited to the above embodiment. For example, in the first and second embodiments, a processing surface such as an oxide film extracted in an actual manufacturing process is used as the suction surface 1a, but this is a suction surface formed in a separate process as a sensor for specific impurities. There may be. Although the case where a semiconductor substrate such as silicon is used as the substrate has been described, the present invention is not necessarily limited to a semiconductor substrate. For example, an insulating substrate such as sapphire, spinel, quartz, or the like, or an adsorption surface for air impurities on a glass substrate. Can be formed. In addition, various modifications can be made without departing from the spirit of the present invention.

[0053]

As described above, according to the aerial impurity treatment method and apparatus of the present invention, it is adsorbed onto the surface of a wafer processed in an actual manufacturing process in a short time and with high sensitivity, and the yield of semiconductor devices can be improved. Aerial impurities that reduce reliability can be analyzed and controlled. Further, an adsorption surface having a high adsorption rate for a specific impurity can be formed on a wafer in a separate process, and this can be used to search for a source of impurities generated in a wide process environment.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of an air impurity evaluation apparatus according to a first embodiment of the present invention, and FIG. (B) is a top view thereof.

FIG. 2 is a view showing a structure of an airborne impurity evaluation device according to a second embodiment of the present invention, and (a) is a cross-sectional view thereof. (B) is a top view thereof.

FIG. 3 is a diagram showing a structure of an air impurity evaluation apparatus according to a third embodiment of the present invention, and (a) is a cross-sectional view thereof. (B) is the bird's eye diagram.

FIG. 4 is a graph showing the relationship between the amount of impurities adsorbed on a wafer and the yield rate of an oxide film formed on the wafer.

5A and 5B are diagrams showing the effect of the present invention in comparison with the conventional method, and FIG. 5A is a diagram showing analytical data of air impurities by the method of the present invention. (B) is a diagram showing analysis data of air impurities by a conventional method.

FIG. 6 is a diagram showing a comparison between the number of days required for collecting airborne impurities of the present invention and the number of days required by a conventional method.

FIG. 7 is a diagram showing a conventional dust evaluation method using a bare wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 1a ... Adsorption surface 2 ... Substrate mounting mechanism 3 ... Chamber 4 ... Atmosphere 5 ... Pump 6 ... Seal 7 ... Intake port 8 ... Exhaust port 9 ... Temperature adjustable vacuum chuck 10 ... Bare wafer 11 ... Support base 15 … Downflow atmosphere

Claims (11)

[Claims] An adsorption surface provided on a substrate surface is brought into contact with the atmosphere to adsorb impurities contained in the air onto the adsorption surface, and the adsorbed impurities are measured to be contained in the air. A method for evaluating aerial impurities, which comprises evaluating the impurities. 2. The semiconductor device according to claim 1, wherein the substrate is a semiconductor wafer extracted in a wafer processing step of a semiconductor device, and a suction surface provided on the substrate surface has at least an insulating film formed on the semiconductor wafer surface. The method for evaluating airborne impurities according to claim 1, wherein: 3. The insulating film according to claim 2, wherein the insulating film comprises a silicon oxide film, a polycrystalline silicon oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxide film, a titanium oxide film, and a combination thereof. The airborne impurity evaluation method described. 4. The method according to claim 1, wherein the suction surface provided on the substrate surface is one of an adsorption film formed on the substrate, a processed layer on the substrate surface, and an adsorbed film formed on the processed layer on the substrate surface. The method for evaluating airborne impurities according to claim 1, wherein: 5. An air inlet through which air is introduced from above, a substrate on which an adsorption surface for impurities in the air is formed, a substrate mounting mechanism on which the substrate is mounted, and air from below the substrate mounting mechanism. An air impurity evaluation apparatus comprising a chamber having an exhaust port for exhausting air. 6. The chamber has a rotational symmetry with respect to a vertical center axis, the inlet and the outlet have a circular shape, and the center of the inlet and the outlet is the center of the chamber. 6. The air impurity according to claim 5, wherein the substrate is disposed so as to coincide with an axis, and the center of the substrate is horizontally placed on the substrate placing mechanism so as to coincide with a central axis of the chamber. Evaluation device. 7. The chamber has axial symmetry with respect to a vertical central axis, and the air inlet comprises a plurality of air inlets which are larger as being closer to the central axis, wherein the plurality of air inlets are the central axis. 6. The substrate mounting mechanism according to claim 5, wherein the substrate is placed so as to be axially symmetric with respect to the substrate, and the substrate is horizontally mounted on the substrate mounting mechanism such that a center of the substrate coincides with a central axis of the chamber. Air impurity evaluation device. 8. The apparatus according to claim 5, wherein said substrate mounting mechanism supports said substrate from below by point contact. 9. The apparatus according to claim 5, wherein the chamber has a structure that can be vertically separated along an outer periphery thereof.
9. The apparatus for evaluating airborne impurities according to any one of claims 8 to 8. 10. A substrate having an adsorption surface for atmospheric impurities, a vacuum chuck for suction-fixing the substrate, a long side being parallel to the adsorption surface, a short side being perpendicular to the adsorption surface, and An intake port having a rectangular cross section for introducing air from one end of the adsorption surface along the adsorption surface, and an exhaust port for exhausting air from the other end of the adsorption surface facing the intake port. An airborne impurity evaluation device characterized by the above-mentioned. 11. The air impurity evaluation device according to claim 10, further comprising a mechanism for controlling a temperature of the adsorption surface.