JP2003042980A - Thermal desorption analytical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve thermal desorption analytical precision by uniformly heating a sample. SOLUTION: This thermal desorption analytical device is equipped with a sample holder for mounting the sample thereon, a sample chamber for arranging the sample holder in the inside, an infrared heating furnace for heating from the periphery, the sample arranged in the sample chamber in the mounted state on the sample holder, a measuring means for detecting gas desorbed from the sample through heating, and an evacuation means for evacuating the sample chamber, a soaking means (a soaking substrate 13 and a soaking hood 14) for soaking the heat by infrared rays, released from the infrared heating furnace via an absorption medium, and heating the sample by secondary radiation, installed near the sample arranged in the sample chamber in a mounted state on the sample holder 10. The soaking means is formed from molybdenum, tantalum, tungsten, or an alloy composed mainly of at least one among them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature programmed desorption analyzer, and more particularly to a temperature programmed desorption analyzer which is improved for uniform heating of a sample in an infrared heating furnace.

[0002]

2. Description of the Related Art The temperature programmed desorption analysis method is a thermal analysis method for measuring the intensity of the gas desorbed from a sample as a function of the sample temperature when the temperature of a solid sample is raised at a constant rate. Yes, it is also called TDS (Thermal Desorption Spectroscopy) or TPS (Temperature Programmed Desorption). This thermal desorption analysis method consists of a sample chamber in which a sample is placed, an infrared heating furnace for heating the sample in the sample chamber, a mass spectrometer as a measuring means for detecting the desorbed gas, and a measurement environment in a high vacuum atmosphere. And a turbo molecular pump (TMP) for forming

In the thermal desorption analyzer, a sample placed in the sample chamber is heated to a desired temperature (measurement temperature) by infrared irradiation from an infrared heating furnace. The measurement temperature is a thermal analysis method for measuring the intensity of the gas desorbed from the sample as a function of the sample temperature in the thermal desorption analysis method, and therefore has a very significant influence on the analysis accuracy.
Therefore, it is extremely important to uniformly heat the entire sample placed in the sample chamber to a target temperature in order to improve the analysis accuracy.

[0004]

However, in spite of the fact that the amount of infrared rays radiated from the infrared heating furnace varies from place to place, the conventional thermal desorption spectroscopy apparatus is designed to uniformly heat the entire sample. No special measures were taken. Even if it is a small sample, infrared rays from an infrared heating furnace are almost uniformly irradiated to the entire sample, or the entire sample is uniformly heated by heat conduction in the sample. However, such a small sample cannot generate sufficient intensity of the gas because the amount of generated gas is small, and there is a background effect due to a slight impurity gas remaining in the sample chamber. It is not possible to clearly detect the desorbed gas from the.

Under these circumstances, it is preferable to increase the size of the sample and generate sufficient desorbed gas in order to improve the analysis accuracy. However, when the size of the sample is increased, infrared rays from the infrared heating furnace are non-uniformly irradiated to the sample, and there is a problem that the temperature distribution varies throughout the sample, that is, the soaking state deteriorates. In particular, when the entire sample is transparent or when there is a spot in the color of the sample, the heating state of the sample tends to be non-uniform.

Further, the sample temperature is measured by a thermocouple attached to the sample mounting portion of the sample holder for mounting the sample. When the infrared rays from the infrared heating furnace are concentrated on the sample, the heat of the sample is There is also a problem that a temperature change occurs during transmission to the thermocouple via the sample mounting portion, and an accurate sample temperature cannot be measured by the thermocouple.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to uniformly heat a sample to improve the accuracy of thermal desorption analysis. A further object of the present invention is to make it possible to measure the sample temperature with high accuracy by means of a thermocouple attached to the sample mounting portion of the sample holder.

[0008]

In order to achieve the above object, the present invention provides a sample holder for mounting a sample, a sample chamber in which the sample holder is arranged, and a sample holder in a state where the sample holder is mounted in the sample chamber. In a thermal desorption analyzer equipped with an infrared heating furnace that heats the prepared sample from the surroundings, a measurement unit that detects the gas desorbed from the sample by heating, and an exhaust unit that evacuates the sample chamber, a sample holder A uniform heating means was installed around the sample placed in the sample chamber in the state of being attached to the sample chamber to heat the infrared radiation emitted from the infrared heating furnace through the absorption medium to heat the sample with secondary radiation. (Claim 1).

With such a structure, the heat soaked by the soaking means is transferred to the sample from its surroundings, so that the entire sample is uniformly heated and, as a result, highly accurate temperature rising and removal is performed. Separation analysis can be realized.

Here, in the case where the sample holder has a supporting rod formed of a quartz material and a sample mounting portion provided at the tip of the supporting rod, and a thermocouple is attached to the sample mounting portion. The soaking means is preferably provided so as to surround the outer periphery of the sample mounting portion (claim 2).

As a result, the heat soaked by the soaking means can be transmitted to the sample and the sample mounting portion to uniformly heat both of them, so that the sample temperature can be adjusted by the thermocouple attached to the sample mounting portion. Can be accurately measured.

Further, according to the present invention, the sample mounting portion is formed on the upper surface in the shape of a dish on which the sample can be placed, and the soaking means is fixed to the outer sample mounting portion so as to surround the bottom surface and the side surface of the sample mounting portion. And a metal heat equalizing hood (heat absorbing medium) detachably attachable to the heat equalizing substrate so as to surround the outer periphery of the upper surface of the sample mounting portion. It is possible (Claim 3).

As a result, when mounting the sample on the sample mounting portion, the heat equalizing hood can be removed from the heat equalizing substrate to open the outer periphery of the upper surface of the sample mounting portion, so that the mounting of the sample becomes easy.

The soaking means is molybdenum (Mo),
Tantalum (Ta), tungsten (W), or an alloy containing at least one of them as a main component is preferable (claim 4). Furthermore, regarding the sample mounting part,
It is preferably made of molybdenum, tantalum, tungsten, or an alloy containing at least one of them as a main component (claim 5).

These metallic materials release little gas even when heated to a high temperature, so that the generation of gas from other than the sample is suppressed and a clear analysis result with a small background can be obtained. Moreover, in recent years, with the technological innovation of semiconductor devices, silicon (Si) -based materials forming the devices have been occupying a large weight as samples to be subjected to the temperature programmed gas desorption analysis. There is no possibility of reacting with the silicon-based material even in a high temperature region, and therefore, it is possible to realize a highly accurate thermal desorption analysis while achieving uniform heating even for a silicon-based sample.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram schematically showing the overall structure of a thermal desorption spectroscopy apparatus according to an embodiment of the present invention. The thermal desorption spectroscopy apparatus shown in the figure is arranged in the sample chamber 20 in which the sample holder 10 is mounted, the sample holder 20 in which the sample S is mounted, the sample chamber 20 in which the sample holder 10 is disposed, and the sample holder 10 mounted in the sample chamber 20. An infrared heating furnace 30 for heating the sample S from the surroundings, a mass spectrometer 40 having a detector 41 for the gas desorbed from the sample S by heating, and a sample chamber 20.
An exhaust path 50 communicating with the turbo molecular pump 6 for vacuum suction of the gas in the sample chamber 10 via the exhaust path 50.
0, and the detection unit 41 of the mass spectrometer 40 is arranged on the orbit of the gas sucked by the turbo molecular pump 60 and flowing in the exhaust path 50.

The overall structure will be described more specifically. First, the sample chamber 20 is provided with a heat-resistant protective tube 21.
The sample holder 10 is arranged in the sample chamber 20. The infrared heating furnace 30 heats the sample S mounted on the sample holder 10 from around the protective tube 21 by emitting infrared rays.

The exhaust path 50 is formed by a relay chamber 51 and an exhaust chamber 52 communicating with the relay chamber 51.
That is, one end of the protective pipe 21 is connected to one end opening of the relay chamber 51, and the other end opening of the relay chamber 51 is connected to the exhaust chamber 52. Protective tube 2
1 and the relay chamber 51 are connected by a gate valve (not shown). When the protective tube 21 is opened during sample exchange, the gate valve is closed to close the relay chamber 51 side vacuum atmosphere. It is possible to hold.

A turbo molecular pump 60 is connected to the downstream side of the exhaust chamber 52, and the sample chamber 20 and the turbo molecular pump 60 are connected in series via the relay chamber 51 and the exhaust chamber 52. As a result, unnecessary residual gas in the sample chamber 20 is guided to the turbo molecular pump 60 via the exhaust path 50 formed by the relay chamber 51 and the exhaust chamber 52. A rotary pump 61 for roughing is connected to the exhaust chamber 52 together with the turbo molecular pump 60.

The mass spectrometer 40 includes a detector (ion source) 6
1 is arranged on the orbit of the gas flowing inside the relay chamber 51. Specifically, the detection unit 41 is arranged coaxially with the relay chamber 51, and the surface of the detection unit 41 is directed toward the upstream side of the relay chamber 51. With this arrangement, the gas flowing from the sample chamber 20 can be directly guided to the detection unit 41.

Inside the relay chamber 51, a gap 51a is formed around the detection portion 41, and an exhaust path for connecting the sample chamber 20 and the turbo molecular pump 60 is secured through this gap 51a. .

2A and 2B are perspective views showing the structure of the sample holder. In the thermal desorption spectroscopy apparatus having the above-described overall structure, the sample holder 10 is composed of a cylindrical support rod 11 made of a quartz material and a sample mounting portion 12 provided at the tip of the support rod 11. The sample mounting part 12 is
A thermosensitive part (not shown) of a thermocouple is attached. The metal wire forming the thermocouple is guided to the measurement processing unit (not shown) through the hollow portion of the support rod 11.

The sample mounting portion 12 is formed in a dish shape,
The sample S can be arranged on the upper surface thereof. A soaking substrate 13 (heat absorbing medium) is fixed to the side wall and the bottom wall of the sample mounting portion 12 so as to surround the outer surfaces thereof.
A dome-shaped soaking hood 14 (heat absorbing medium) is detachably attached to the soaking substrate 13. FIG. 2A shows a state in which the soaking hood 14 is mounted on the soaking substrate 13. In this mounting state, the periphery of the sample mounting portion 12 and the sample S mounted on the upper surface of the soaking hood 14 are evenly distributed. Thermal board 13
And soaking hood 14 surrounds it.

The soaking substrate 13 and soaking hood 14 described above
Is a soaking means for soaking the heat of the infrared rays emitted from the infrared heating furnace 30 through the absorbing medium and heating the sample S with the secondary radiation, which has a high absorptivity of infrared rays and has a high thermal conductivity. It is composed of a metal material having a good rate.
Specifically, the soaking substrate 13 and the soaking hood 14 are formed of molybdenum, tantalum, tungsten, or an alloy containing at least one of them as a main component. These metal materials have a high infrared absorption rate and a good thermal conductivity, and emit little gas even when heated to a high temperature. Furthermore, each metal material is a silicon-based material even in a high temperature region. It has the characteristic of not reacting.

Therefore, generation of gas from other than the sample is suppressed, and clear analysis results with a small background can be obtained. Further, with technological innovation of the semiconductor device, the target of the temperature rising gas desorption analysis. Highly accurate thermal desorption analysis can be realized while achieving soaking even for a silicon-based sample, which has occupied a large weight as a sample. Platinum (Pt) is also applicable as a metal material having a high infrared absorptivity and a good thermal conductivity, but platinum is not preferable because it may react with a silicon-based sample under high temperature heating.

In the present embodiment, for the same reason,
The sample mounting portion 12 is also formed of molybdenum, tantalum, tungsten, or an alloy containing at least one of them as a main component.

Among these metallic materials, a metallic material (for example, molybdenum) that easily oxidizes when exposed to air under high temperature heating is included, but in the thermal desorption analyzer, a turbo molecular pump 60 is used. By sample chamber 20
Because of the high vacuum inside, there is no risk of oxidation of these metallic materials during analysis.

Next, the operation of the above-mentioned temperature programmed desorption analyzer will be described. Prior to the measurement, the sample S is placed on the sample mounting portion 12 of the sample holder 10. At this time, soaking hood 14
If the sample is removed from the soaking board 13, the sample mounting part 12
Since the upper surface of the sample S is open, the sample S can be easily placed on the upper surface of the sample mounting portion 12 (FIG. 2B). After arranging the sample S, the soaking hood 14 is attached to the upper part of the soaking substrate 13, and the periphery of the sample S and the sample mounting portion 12 is surrounded by these soaking means (FIG. 2A). In this state, as shown in FIG. 1, the sample holder 10 is arranged in the sample chamber 20. The soaking hood 14 and the soaking substrate 13
Are arranged in the highest temperature region of the infrared heating furnace 30.

Next, a gate valve (not shown) provided at the connecting portion between the protective tube 21 and the relay chamber 51 is opened, and the rotary pump 61 first discharges the residual gas in the sample chamber 20 and the exhaust path. At this time, although the detection part 41 of the mass spectrometer 40 is arranged inside the relay chamber 51, since a gap 51a is formed around the detection part 41, the residual gas flows through the gap 51a. However, it will be promptly discharged. Then, the turbo molecular pump 60 is operated to form a high vacuum atmosphere. By sufficiently discharging the residual gas in this manner, the background spectrum (BG) of the desorbed gas analysis can be suppressed to a low level.

After making the inside of the sample chamber 20 and the exhaust path a high vacuum atmosphere, the infrared heating furnace 30 is activated to start the measurement. Infrared rays emitted from the infrared heating furnace 30 are absorbed by the heat equalizing substrate 13 and the heat equalizing hood 14 to heat those members. Then, the soaking substrate 13 and the soaking hood 1
The heat generated in the sample No. 4 is transmitted through these members, and the sample S and the sample mounting portion 12 arranged inside thereof are also transferred.
Is uniformly transmitted to the secondary radiation. In this way, the entire sample S is heated uniformly, so that highly accurate thermal desorption analysis can be realized. Moreover, since the sample mounting part 12 is also heated uniformly under the same conditions as the sample S,
A thermocouple (not shown) attached to the sample mounting portion 12 makes it possible to accurately measure the sample temperature.

The sample is vaporized with heating to generate a desorbed gas. The desorbed gas flows from the sample chamber 20 to the relay chamber 51 by the suction force of the turbo molecular pump 60.
Since the detector 41 of the mass spectrometer 40 is arranged on the trajectory of the desorbed gas flowing in this way, the desorbed gas can be efficiently guided to the detector 41. As a result, the desorbed gas can be efficiently captured by the detection unit 41, and highly accurate gas analysis can be realized.

[0032]

As described above, according to the present invention,
Since the heat soaked by the soaking means is transferred to the sample from the surroundings by the secondary radiation, the entire sample is uniformly heated, and as a result, highly accurate thermal desorption analysis can be realized. .

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing an overall structure of a thermal desorption analysis apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a sample holder, (a) shows a state in which a soaking hood is attached, and (b) shows a state in which the soaking hood is removed.

[Explanation of symbols]

10: Sample holder 11: Support rod 12: Sample mounting part 13: Soaking board 14: Soaking hood 20: Sample chamber 30: Infrared heating furnace 40: mass spectrometer 41: Detector 50: Exhaust path 51: Relay chamber 52: Exhaust chamber 60: Turbo molecular pump

Claims (5)

[Claims] 1. A sample holder on which a sample is mounted, a sample chamber in which the sample holder is disposed, an infrared heating furnace which heats a sample placed in the sample chamber from the surroundings in a state of being mounted on the sample holder, and heating. In a thermal desorption analyzer equipped with a measuring means for detecting the gas desorbed from the sample and an exhaust means for evacuating the inside of the sample chamber, the sample desorption analyzer is arranged inside the sample chamber while being attached to the sample holder. An apparatus for thermal desorption spectroscopy characterized in that a soaking unit for soaking the heat of infrared rays emitted from the infrared heating furnace through an absorption medium and heating the sample with secondary radiation is provided around the sample. . 2. The thermal desorption analysis apparatus according to claim 1, wherein the sample holder includes a support rod formed of a quartz material and a sample mounting portion provided at a tip end portion of the support rod. A thermocouple is attached to the mounting part, and the soaking means is provided so as to surround the outer periphery of the sample mounting part. 3. The thermal desorption spectroscopy apparatus according to claim 2, wherein the sample mounting part is formed in a dish shape on the top surface of which the sample can be placed, and the soaking means is a bottom surface of the sample mounting part. And a soaking board made of metal fixed to the outer sample mounting part so as to surround the side surface and a soaking hood made of metal that can be detachably attached to the soaking board so as to surround the outer periphery of the upper surface of the sample mounting part. A temperature programmed desorption analysis apparatus comprising: 4. The temperature programmed desorption analyzer according to claim 2, wherein the soaking means is formed of molybdenum, tantalum, tungsten, or an alloy containing at least one of them as a main component. Thermal desorption analyzer. 5. The thermal desorption spectroscopy apparatus according to claim 2, wherein the sample mounting portion is made of molybdenum, tantalum, tungsten, or an alloy containing at least one of them as a main component. A temperature programmed desorption analysis apparatus characterized by being provided.