JP2001330591A - Reduction method of fluorine in thermal desorption gas analytical device chamber and thermal desorption gas analytical method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce background of fluorine in a vacuum chamber in a thermal desorption gas analytical device. SOLUTION: This method has at least a first step for evacuating the vacuum chamber up to the prescribed degree of vacuum (S01), a second step for placing a dummy sample having silicon oxide including carbon at the rate of several percent on a sample stage in the vacuum chamber (S02), a third step for heating the dummy sample to raise the temperature at a prescribed programming rate, and to desorb the carbon from the dummy sample (S03). The carbon in the dummy sample is desorbed in the vacuum chamber, reacted and bonded actively with fluorine remaining in the vacuum chamber to form CFx-based desorption gas, and desorbed from the inner wall of an analytical chamber. The desorbed CFx-based desorption gas is exhausted by a vacuum pump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing fluorine in a chamber for a thermal desorption gas analyzer and a method for analyzing a thermal desorption gas, and relates to a thermal desorption gas analysis using a silicon oxide film containing carbon. The present invention relates to a method for reducing fluorine in an apparatus chamber.

[0002]

2. Description of the Related Art A semiconductor chip is manufactured through a number of manufacturing steps in which processing, cleaning, vapor deposition and the like by chemicals are repeatedly performed. To improve the manufacturing yield, any part of these manufacturing steps is required. You have to find out how to improve. For this,
2. Description of the Related Art A thermal desorption spectrometer for detecting desorption gas from a semi-finished product or a semiconductor chip in a product state is known.
In recent years, this device has attracted attention as a device that can detect even low-level gases that could not be measured until now.

[0003] The thermal desorption gas analyzer uses a semi-finished product or product extracted during or during the manufacturing process as a sample, and leaves the sample in an extremely high vacuum to heat the sample. As the temperature of the sample increases (temperature rise), trace substances such as chemicals adsorbed on the sample surface sequentially desorb in gaseous form. By capturing this desorbed gas in a vacuum atmosphere and analyzing its mass, the composition of the desorbed gas can be specified. In the heating process, molecules and atoms with small heats of adsorption, that is, molecules with small desorption energies are sequentially desorbed, and analysis of the desorption spectrum with respect to the sample temperature reveals the adsorption molecular weight, the reaction process of the adsorbed molecules, and the activation energy. Information is obtained.

[0004]

However, in a thermal desorption gas analyzer, in order to detect a trace substance contained in a sample, it is necessary to reduce gas remaining in a vacuum chamber of the apparatus as much as possible. is necessary. The residual gas adsorbed on the inner wall of the vacuum chamber desorbs as the temperature of the sample rises and appears on the desorption spectrum as a background gas. In other words, this residual gas causes the detection limit of the trace substance to be lowered. Among these residual gases, the background of fluorine is a serious problem, and reducing fluorine in the chamber is urgently required to improve the detection limit.

FIG. 6 shows a desorption spectrum showing the background of fluorine measured by the thermal desorption gas analyzer. The desorption spectrum shown in FIG. 6 is obtained by raising the temperature of a single-crystal silicon piece (bare silicon) once in a vacuum chamber to desorb the substance adsorbed on the surface.
It is a TDS profile (desorption spectrum) of fluorine when this bare silicon was heated in a vacuum chamber. In other words, this desorption spectrum shows the background of fluorine from the vacuum chamber when the temperature is raised in the absence of desorption gas from bare silicon. FIG. 7 shows the background of fluorine when the temperature of bare silicon in the absence of desorbed gas was similarly increased after the temperature of a sample sufficiently containing fluorine was increased in a vacuum chamber. It is a separation spectrum. The intensity of fluorine in FIG. 7 is about 4 to 5 times stronger than that in FIG. In other words, it can be seen that when the temperature of the sample containing sufficient fluorine is increased in the vacuum chamber, the fluorine remains in the chamber. An increase in the background of fluorine causes a problem that the detection limit of the trace substance in the sample is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems of the prior art, and an object thereof is to reduce the background of fluorine in a vacuum chamber in a thermal desorption gas analyzer. It is to be. That is, it is an object of the present invention to provide a method for reducing fluorine in a chamber for a thermal desorption gas analyzer.

Another object of the present invention is to provide a thermal desorption gas analysis method capable of detecting trace substances desorbed from a sample with a small background of fluorine.

[0008]

Means for Solving the Problems In order to achieve the above object, a first feature of the present invention is that gas generated from the surface and bulk of a sample is desorbed as the temperature of the sample increases, and the desorbed gas is removed. What is claimed is: 1. A method for reducing fluorine in a vacuum chamber in a thermal desorption gas analyzer for capturing and analyzing in a vacuum atmosphere, comprising: a first step of evacuating the vacuum chamber to a predetermined degree of vacuum; A second step of placing a dummy sample having silicon oxide contained in a proportion on a sample stage in a vacuum chamber, and heating the dummy sample to raise the temperature at a predetermined temperature raising rate, thereby removing carbon from the dummy sample. And a third step of desorbing. A method for reducing fluorine in a chamber for thermal desorption spectroscopy having at least a step of desorbing. Here, the first step and the second step may be performed in a different order. That is, the dummy sample may be placed on the sample stage in the vacuum chamber first, and then the vacuum chamber may be evacuated to a predetermined degree of vacuum. In the first step, the “predetermined degree of vacuum” means a degree of vacuum low enough to analyze the desorbed gas. In the third step, the temperature rise of the dummy sample ends at about 1000 ° C. The dummy sample is 1
It is desirable that the material be composed of a material that releases a small amount of gas other than carbon when the temperature is raised to about 000 ° C. The dummy sample may be silicon oxide itself containing several% of carbon. In the third step, the “predetermined heating rate” is desirably lower than the heating rate used during normal analysis of the thermal desorption gas analyzer, and in particular, is one of the heating rates used during normal analysis. It is desirable that the speed be about / 10. Destruction of the desorbed gas detector and other vacuum equipment due to the desorption of a large amount of carbon can be prevented. Note that the carbon content is also several percent for the same reason.
It is desirable to keep it.

According to a first feature of the present invention, when a temperature of a dummy sample containing silicon oxide containing carbon at a ratio of several percent is raised, carbon in the dummy sample is desorbed in a vacuum chamber. The desorbed carbon actively reacts with and binds to the fluorine remaining in the vacuum chamber, and CFx
A system desorption gas is formed and desorbed from the inner wall of the analysis chamber. The desorbed CFx-based desorption gas is exhausted by a vacuum pump. As described above, fluorine remaining in the vacuum chamber can be removed using the dummy sample containing carbon. Therefore, the background of fluorine in the vacuum chamber of the thermal desorption gas analyzer can be reduced.

In the first aspect of the present invention, the third step comprises detecting a desorbed gas containing fluorine while desorbing carbon from the dummy sample by raising the temperature of the dummy sample and detecting the temperature of the dummy sample. Is a step of measuring a desorption spectrum for After the third step, a step of removing the dummy sample from the vacuum chamber, a step of mounting a new dummy sample having silicon oxide containing carbon at a ratio of several% on a sample stage of the vacuum chamber, Maintaining the temperature of the dummy sample at the temperature of the lowest temperature peak in the desorption spectrum. By maintaining the temperature of the new dummy sample at the lowest peak temperature in the fluorine-based desorption spectrum, the reaction between carbon and fluorine is promoted, and the effect of removing fluorine is further increased. The holding time is preferably about 20 to 30 minutes. Further, in the third step, in order to detect the desorbed gas containing fluorine, the change in the degree of vacuum in the analysis chamber may be simply measured. It is desirable to measure the change in Therefore, in the former case, the desorption spectrum indicates the profile of the degree of vacuum in the analysis chamber, and in the latter case, the desorption spectrum indicates the desorption spectrum of a specific fluorine-based desorption gas. In the steps after the third step, the new dummy sample may be a different sample of the same type as the dummy sample. In other words, it is not a dummy sample in which carbon has been desorbed after the temperature has been raised once, but a dummy sample of the same type having silicon oxide still containing carbon at a ratio of several percent.

A second feature of the present invention is that a temperature-adsorbed desorption in which the gas adsorbed on the surface of the sample is desorbed as the temperature of the sample is increased and the desorbed gas is captured and analyzed in a vacuum atmosphere. A gas analysis method, comprising: (1) a first step of evacuating the inside of a vacuum chamber to a predetermined degree of vacuum; and (2) placing a dummy sample having a silicon oxide film containing carbon at a ratio of several percent in a vacuum chamber. (3) a third step of mounting the dummy sample on the sample stage, heating the dummy sample at a predetermined rate, and removing carbon from the dummy sample; A) a fourth step of removing the dummy sample from the vacuum chamber, (5) a fifth step of placing the analysis sample to be analyzed on the sample stage in the vacuum chamber, and (6) heating the analysis sample. Raises at a predetermined heating rate While, by detecting the desorbed gas from the analysis sample, it is that it is the sixth step and the temperature-programmed desorption gas analysis method with the measuring the desorption spectrum for temperature analysis sample.

According to the second feature of the present invention, when the temperature of the dummy sample containing silicon oxide containing carbon at a ratio of several percent is raised, the carbon in the dummy sample is desorbed in the vacuum chamber. The desorbed carbon actively reacts with and binds to the fluorine remaining in the vacuum chamber, and CFx
A system desorption gas is formed and desorbed from the inner wall of the analysis chamber. The desorbed CFx-based desorption gas is exhausted by a vacuum pump. As described above, fluorine remaining in the vacuum chamber can be removed using the dummy sample containing carbon. Therefore, the background of fluorine in the vacuum chamber of the thermal desorption gas analyzer can be reduced, and the thermal desorption gas analysis with a high detection limit can be performed on the analysis sample to be analyzed. .

In the second aspect of the present invention, the third step comprises detecting a desorbed gas containing fluorine while desorbing carbon from the dummy sample by raising the temperature of the dummy sample and detecting the temperature of the dummy sample. Is a step of measuring a desorption spectrum for Also, between the fourth step and the fifth step, a step of mounting a new dummy sample having silicon oxide containing carbon at a ratio of several percent on a sample stage of a vacuum chamber; , At the temperature of the coldest peak in the desorption spectrum, and removing the new dummy sample from the vacuum chamber.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a thermal desorption gas analyzer according to an embodiment of the present invention. As shown in FIG. 1, a thermal desorption gas analyzer 1 includes an analysis chamber 2 for actually measuring a desorbed gas from a sample, and a load lock chamber for transferring a sample into and out of the analysis chamber 2. 3 is a load-lock type vacuum apparatus including two vacuum chambers.

The load lock chamber 2 has a sample transfer unit 4 for moving a sample between the load lock chamber 2 and the analysis chamber 3. The sample transfer unit 4 includes a transfer stage 5 on which a sample is mounted, and a transfer rod 6 for moving the transfer stage 5 to the analysis chamber 3. Load lock chamber 2
Is connected to a magnetic levitation type turbo molecular pump (TMP) 8 via a gate valve 7, and a rotary pump 9 is connected to a lower stage of the TMP 8. Further, a vacuum gauge 10 is connected to the load lock chamber 2 via a port.

The analysis chamber 3 is a cylindrical vacuum chamber having a total volume of 17 liters and connected to the load lock chamber 2 via a gate valve 11.
In order to reduce the gas adsorbed on the inner wall of the chamber, the inner wall of the chamber is subjected to complex electrolytic polishing to reduce the surface roughness of the inner wall. A quartz sample stage 12 on which a sample is placed is disposed substantially at the center of the cylindrical analysis chamber 3.
The sample stage 12 is connected to one end of a transparent quartz rod 13. The transparent quartz rod 13 is attached to the analysis chamber 3
An infrared heating unit 14 for heating the sample is connected to the other end of the transparent quartz rod 13. Infrared rays are emitted from the infrared heating unit 14, and the infrared rays irradiate the rear surface of the sample on the sample stage 12 as inside the transparent quartz rod 13. This infrared ray has a peak at a wavelength of 0.9 μm, and only the sample can be heated without heating the quartz rod 13 and the sample stage 12 transparent to this wavelength. The infrared heating unit 14 allows the sample on the sample stage 12 to be
The temperature can be raised to 000 ° C. The temperature of the infrared heating unit 14 is controlled by a temperature control device 16 controlled by a computer unit 15. A magnetically levitated turbo molecular pump (TMP) 17 is connected to the analysis chamber 3 via a port, and a rotary pump 18 is connected to a lower stage of the TMP 17. This TMP1
7 has a pumping speed of 400 l / s. TMP
17 and the rotary pump 18, the degree of vacuum in the analysis chamber 3 is 1 × 1 in a state where sufficient degassing is performed.
0 ^-7 Pa (about ^1x10 -9 Torr) reach to below.
Furthermore, a vacuum gauge 19 and a quadrupole mass spectrometer (QMS) 20 for detecting desorbed gas from the sample are connected to the analysis chamber 3 via ports. . QMS 20
Computer unit 1 same as infrared heating unit 14
5 is connected.

Next, a method for reducing fluorine in an analysis chamber according to an embodiment of the present invention using the thermal desorption gas analyzer 1 having the above configuration will be described with reference to FIG. FIG. 2 is a flowchart showing a method for reducing fluorine in the analysis chamber of the thermal desorption gas analyzer according to the embodiment of the present invention.

(A) First, in step S01, T
Using the MP 17 and the rotary pump 19, the inside of the analysis chamber 3 is evacuated to a sufficiently low vacuum for analyzing the desorbed gas. On the other hand, load lock chamber 2
The interior of is opened to atmospheric pressure by a method such as nitrogen purge,
Stage 5 for transferring dummy sample from sample entry / exit port 21
Place on top. The dummy sample has silicon oxide containing carbon at a ratio of several percent. Next, the sample inlet / outlet port 21 is closed, the gate valve 7 is opened, and the rotary pump 9 and the TMP 8 are sequentially operated to evacuate the load lock chamber 2 to a predetermined vacuum degree.

(B) Next, the gate valve 11 between the analysis chamber 3 maintaining a predetermined degree of vacuum and the load lock chamber 2 evacuated to the predetermined degree of vacuum is opened. By operating the transfer rod 6, the transfer stage 5 is moved from the load lock chamber 2 to the analysis chamber 3,
In step S02, the dummy sample is placed on the sample stage 12 in the analysis chamber 3. Transfer stage 5
To the load lock chamber 2 and the gate valve 11
Close.

(C) Next, the infrared heating unit 14 is operated to irradiate the back surface of the dummy sample on the sample stage 12 with infrared light. In step S03, the temperature of the dummy sample is raised to 1000 ° C. at a predetermined temperature rising rate by adjusting the intensity of the infrared ray to be irradiated. Here, the predetermined heating rate is a rate (0.1 ° C./sec) that is about ten times slower than the heating rate (1 ° C./sec) used during normal analysis. A large amount of carbon contained in the dummy sample is desorbed, and this desorbed gas is QMS 20, vacuum gauge 19, or TM
This is to prevent P17 and the like from being destroyed. Also,
It is desirable to keep the carbon content of the dummy sample at a few percent for the same reason. The temperature of the dummy sample is constantly monitored by the temperature control device 16, and the computer unit 15 controls the infrared heating unit 14 so as to maintain a predetermined heating rate. When the temperature of the dummy sample is raised, it is considered that the desorbed gas of carbon may adhere to the inside of the analysis chamber 3. Therefore, the analysis chamber 3 is heated to about 50 to 100 ° C. using a ribbon heater or a rubber heater.

(D) Next, the infrared heating unit 14 is turned off to stop heating the dummy sample. After sufficiently lowering the temperature of the dummy sample, the gate valve 11 is opened, the transfer rod 6 is moved into the analysis chamber 3, and the dummy sample on the sample stage 12 is transferred onto the transfer stage 5. In step S04, the transfer stage 5 is returned from the analysis chamber 3 to the load lock chamber 2,
The dummy sample is taken out of the analysis chamber 3. After closing the gate valve 11, the load lock chamber 2 is opened to the atmospheric pressure by a method such as nitrogen purging, and a dummy sample is taken out from the sample port 21. After the temperature of the dummy sample is raised, it is considered that the CFx-based or SiFx-based desorbed gas is reattached to the filament of the vacuum gauge 19 in the analysis chamber 3. The gas adhering to the filament is blown off by flowing it through the filament.

(E) In step S05,
Instead of the dummy sample, an analysis sample, which is an actual analysis target, is mounted on the sample stage 12 in the same procedure as in the case of the dummy sample. In step S06, the desorption gas from the analysis sample is analyzed while the temperature of the analysis sample is raised using the infrared heating unit 14, the QMS 20, and the like, and a desired desorption spectrum is measured. After the temperature of the analysis sample is raised, the analysis sample is taken out of the analysis chamber 3 using the sample transfer unit 4 in step S07.

In step S03, carbon is reduced to several percent.
When the temperature of the dummy sample having the silicon oxide contained in the ratio is increased, carbon in the dummy sample is desorbed. The desorbed carbon actively reacts and combines with fluorine remaining in the analysis chamber 3 to form a CFx-based gas and desorbs from the inner wall of the analysis chamber 3. The desorbed CFx-based gas is exhausted by a vacuum pump (17, 18). In this manner, fluorine remaining in the analysis chamber 3 can be removed using the dummy sample containing carbon. Therefore, according to the embodiment of the present invention, in step S06, the background of fluorine in the analysis chamber 3 of the thermal desorption gas analyzer 1 can be reduced, and the analysis sample to be analyzed can be reduced. Analysis with a high detection limit can be performed.

(Modification) By adding the following steps to the flowchart of the method for removing fluorine shown in FIG. 2, the effect of removing fluorine is further increased. In a modified example, a method of removing more fluorine by maintaining the temperature of the dummy sample at a temperature at which a large amount of fluorine-based desorption gas is generated will be described with reference to FIG. FIG. 3 is a flowchart showing a fluorine reduction method according to a modification.

(1) First, as in the flowchart of FIG. 2, in steps S01 and S02, the analysis chamber is evacuated to a vacuum and a dummy sample having silicon oxide containing carbon at a ratio of several percent is removed. Place on the sample stage inside.

(2) Next, in step S03 of FIG. 2, only the temperature of the dummy sample was raised. However, in a modified example, in step S10, the temperature of the dummy sample was raised to 1000 ° C. and at the same time, the fluorine-based (Fx ) Is analyzed. Fx-based radicals are fluorine (F) having an atomic weight (M / z) of 19, 31 carbon monofluoride (CF), 50 carbon difluoride (CF ₂ ), and 85 silicon trifluoride (SiF ₃ ). , 104 silicon tetrafluoride (SiF ₄ )
And CFx-based or SiFx-based desorption gas. Specifically, the desorption spectrum of the fluorine-based M / z dummy sample with respect to the temperature is measured using the QMS 20. If a peak appears in the fluorine-based desorption spectrum, it indicates that the reaction / bonding between carbon and fluorine is progressing in the analysis chamber 3. If a peak is found in the fluorine-based desorption spectrum P01 measured by the QMS 20, the process proceeds to the following steps.

(3) Next, after the heating of the dummy sample is completed, the dummy sample is taken out of the analysis chamber 3 using the sample transfer unit 4 in step S11.

(4) Next, a new dummy sample having silicon oxide containing carbon at a ratio of several% is prepared.
In step S12, the sample is placed on the sample stage 12 in the analysis chamber 3 in the same manner as described above. here,
The new dummy sample may be a different sample of the same type as the dummy sample. In other words, it is not a dummy sample in which carbon has been desorbed after the temperature has been raised once, but a dummy sample of the same type having silicon oxide still containing carbon at a ratio of several percent.

(5) Next, a new dummy sample is heated using the infrared heating unit 14. And step S
In step 13, the temperature of the new dummy sample is held at the temperature of the first peak in the fluorine-based desorption spectrum, that is, the temperature of the peak appearing at the lowest temperature, for about 20 to 30 minutes by using the temperature controller 16.

(6) Next, after stopping the heating of the new dummy sample and sufficiently lowering the temperature of the new dummy sample, the gate valve 11 is opened, and the transfer rod 6 is moved into the analysis chamber 3. Then, the dummy sample on the sample stage 12 is transferred onto the transfer stage 5. In step S14, the transfer stage 5 is returned from the analysis chamber 3 to the load lock chamber 2, and a new dummy sample is taken out of the analysis chamber 3. After closing the gate valve 11, the load lock chamber 2 is opened to atmospheric pressure by a method such as nitrogen purge, and a new dummy sample is taken out from the sample port 21.

(7) Then, step S0 shown in FIG.
In the same manner as in the steps after step 5, an analysis sample, which is an actual analysis target, is placed on the sample stage 12 instead of a new dummy sample, and the analysis sample is heated to measure a desorption spectrum.

In step S13, the temperature of the new dummy sample is maintained at the lowest peak temperature in the fluorine-based desorption spectrum for about 20 to 30 minutes, so that the reaction between carbon and fluorine is promoted, and the fluorine is removed. The effect of removing further increases. In step S10, in order to analyze the fluorine-based (Fx-based) desorbed gas, the vacuum gauge 19 is used without measuring the desorption spectrum of the fluorine-based radical with respect to the temperature of the dummy sample using the QMS 20. It may be used to simply measure the change in the degree of vacuum in the analysis chamber. In this case, the desorption spectrum is a profile of the degree of vacuum in the analysis chamber with respect to the temperature of the dummy sample.

(Experimental Example) Next, an experiment performed by the inventor will be described with reference to FIGS. The inventor conducted the following experiment in order to verify the effect of reducing the background of fluorine by the above-described method for reducing fluorine in the analysis chamber. The experiment described below was performed after the measurement of the background of fluorine performed by the inventor illustrated in FIGS. 6 and 7.

FIG. 6 shows a desorption spectrum of fluorine when the temperature of bare silicon after degassing was raised. FIG. 7 shows a desorption spectrum of a sample containing sufficient fluorine after the temperature was raised in the analysis chamber. 4 shows a desorption spectrum of fluorine when bare silicon after gas is heated. As described above, as shown in FIGS. 6 and 7, before and after the sample containing sufficient fluorine is heated in the analysis chamber, the background of fluorine increases by about 5 to 6 times. Would. The inventor measured the desorption spectrum shown in FIG. 7 and then measured the fluorine (M / z = 1) when the temperature of the dummy sample containing carbon was increased.
The desorption spectrum of 9) was measured. Note that the dummy sample is a silicon oxide film (SO
A single crystal silicon piece on which a G film was formed was used. FIG. 4 shows the results. As shown in FIG. 4, a peak was observed at around 150 ° C. in the desorption spectrum, and at a temperature higher than 150 ° C., the intensity of fluorine decreased with increasing temperature. Normally, in a thermal desorption gas analyzer, the background level rises as the temperature rises. Therefore, in FIG. 4, since the intensity of fluorine decreases as the temperature rises after 150 ° C., the carbon in the dummy sample and the residual fluorine gas in the analysis chamber react and bond violently at around 150 ° C. This shows that fluorine in the analysis chamber was removed by forming desorbed gas. Also, at a temperature of 150 ° C. or lower, most of the fluorine remaining on the inner wall of the analysis chamber has already been removed, indicating that the strength of fluorine has decreased.

The inventor measured the desorption spectrum at the time of raising the temperature of the dummy sample shown in FIG. 4, then raised the temperature of the degassed bare silicon again, and measured the desorption spectrum of fluorine. FIG. 5 is a fluorine desorption spectrum showing the result. FIG. 5 is a desorption spectrum showing the background of fluorine similarly to FIG. 7, and it can be seen that the background of fluorine is clearly reduced as compared with FIG. That is, it was verified that the background of fluorine was reduced by raising the temperature of the dummy sample containing carbon.

[0036]

As described above, according to the present invention, the background of fluorine in the vacuum chamber can be reduced in the thermal desorption gas analyzer. That is, it is possible to provide a fluorine background reduction method in the thermal desorption gas analyzer.

Further, according to the present invention, it is possible to provide a thermal desorption gas analysis method in which the background of fluorine is small and a trace substance desorbed from a sample can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a thermal desorption gas analyzer according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a thermal desorption gas analysis method according to an embodiment of the present invention.

FIG. 3 is a flow chart showing a method for analyzing degassed gas according to a modification.

FIG. 4 is a desorption spectrum from a dummy sample containing carbon according to the embodiment of the present invention.

FIG. 5 is a desorption spectrum from bare silicon after the temperature of the dummy sample is increased according to the embodiment of the present invention.

FIG. 6 is a desorption spectrum from bare silicon after degassing according to the prior art.

FIG. 7 is a desorption spectrum from bare silicon after the temperature of a fluorine-containing substance is raised according to the conventional technique.

[Explanation of symbols]

 1 Thermal Desorption Gas Analyzer 2 Load Lock Chamber 3 Analysis Chamber 4 Sample Transfer Unit 5 Transfer Stage 6 Transfer Rod 7, 11 Gate Valve 8, 17 Turbo Molecular Pump (TMP) 9, 18 Rotary Pump (RP) 10, 19 Vacuum gauge 12 Sample stage 13 Transparent quartz rod 14 Infrared heating unit 15 Computer unit 16 Temperature controller 20 Quadrupole mass spectrometer (QMS) 21 Sample access port

Claims (4)

[Claims] 1. A temperature rising desorption gas analyzer for desorbing a gas generated from the surface and bulk of the sample as the temperature of the sample rises and capturing and analyzing the desorbed gas in a vacuum atmosphere. A method for reducing fluorine in a chamber, comprising: a first step of evacuating the inside of a vacuum chamber to a predetermined degree of vacuum; and a step of forming a dummy sample having silicon oxide containing carbon at a ratio of several% in the vacuum chamber. A second step of placing the stage on a stage; and a third step of heating the dummy sample and increasing the temperature at a predetermined rate to desorb carbon from the dummy sample. To reduce fluorine in the chamber of the thermal desorption gas analyzer. 2. The method according to claim 1, wherein the third step comprises: detecting a desorption gas containing fluorine while raising the temperature of the dummy sample to desorb carbon from the dummy sample; Measuring a spectrum, after the third step, removing the dummy sample from the vacuum chamber; and removing a new dummy sample having silicon oxide containing carbon at a ratio of several percent in the vacuum chamber. 2. The method according to claim 1, further comprising: mounting the sample on the sample stage; and maintaining the temperature of the new dummy sample at the temperature of the lowest temperature peak in the desorption spectrum. 3. Method for reducing fluorine in chamber of gas separation analyzer. 3. A thermal desorption gas analysis method in which a gas adsorbed on the surface of the sample is desorbed as the temperature of the sample increases, and the desorbed gas is captured and analyzed in a vacuum atmosphere. A first step of evacuating the vacuum chamber to a predetermined degree of vacuum, and a second step of mounting a dummy sample having a silicon oxide film containing carbon at a ratio of several percent on a sample stage in the vacuum chamber. A third step of heating the dummy sample to increase the temperature at a predetermined rate to remove carbon from the dummy sample; and a fourth step of removing the dummy sample from the vacuum chamber.
And a fifth step of mounting an analysis sample, which is an object to be analyzed, on the sample stage in the vacuum chamber. The analysis is performed while heating the analysis sample at a predetermined temperature raising rate. And a sixth step of detecting a gas desorbed from the sample and measuring a desorption spectrum with respect to a temperature of the analysis sample. 4. The method according to claim 3, wherein the third step comprises: detecting a desorption gas containing fluorine while raising the temperature of the dummy sample to desorb carbon from the dummy sample; A step of measuring a spectrum, wherein a new dummy sample having silicon oxide containing carbon at a ratio of several percent is placed on the sample stage of the vacuum chamber between the fourth step and the fifth step. And maintaining the temperature of the new dummy sample at the temperature of the lowest temperature peak in the desorption spectrum; and removing the new dummy sample from the vacuum chamber. Claim 3
The thermal desorption gas analysis method described.