JP2779141B2 - Glow discharge emission spectroscopy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glow discharge emission spectroscopy method for analyzing generated light while sputtering a sample.

[0002]

2. Description of the Related Art When a DC or high-frequency high voltage is applied between two electrodes in an argon (Ar) atmosphere at a gas pressure of about 4 to 10 Torr, a glow discharge occurs to generate Ar ions. The generated Ar ions are accelerated by a high electric field, collide with the surface of the cathode, and knock out substances existing there. This phenomenon is called sputtering, and the sputtered particles (atoms, molecules, and ions) are excited in the plasma and emit light having a wavelength specific to the element when returning to the ground state. An analysis method in which the emitted light is separated by a spectroscope to identify elements is called a glow discharge emission spectral analysis method.

A hollow anode type grim glow discharge tube 1 as shown in FIG. 5 is generally used as a glow discharge tube in an analyzer embodying the above-described glow discharge emission spectral analysis method. In the grim glow discharge tube 1, a support block 2 serving as a cathode and an anode block 3 are joined via a Teflon washer 4 which is an insulator. The anode block 3 has an argon gas supply hole 3a and first and second evacuation holes 3b and 3c, and the glow discharge space V in the tube has a rare gas atmosphere of argon (4 to 10 Torr).
It has been. A hollow anode tube 3d is integrally formed in the glow discharge space V of the anode block 3, and this anode tube 3d is housed in the glow discharge space V inside the support block 2 through the Teflon washer 4. I have. The sample 5 to be analyzed is vacuum-adsorbed to the sample holder 7 and the surface 5a including the analysis surface is pressed in an airtight manner to the support block 2 so as to face the anode tube via a sealing member 6 such as an O-ring. ing.

[0004] The Grimm glow discharge tube 1 generates a glow discharge by applying a high voltage between the anode block 3 and the support block 2 by the power supply unit 9, and also supplies the sample 5 to the sample 5 through the support block 2 which is generally made of copper. Apply a negative voltage,
The sample 5 is sputtered by colliding positive ions of argon generated by the generation of the glow discharge with the surface 5 a of the sample 5. The sample 5 and the hollow anode tube 3d are cooled through the support block 2 by introducing the coolant K from the coolant introduction passage 2a of the support block 2 into the jacket 2b and feeding it to the coolant discharge passage 2c. doing.

[0005]

The glow discharge emission spectroscopy method using the glow discharge tube 1 described above
In particular, substances sputtered and scattered from the surface of the sample 5
A large amount adheres to the inner wall surface and the distal end surface of the anode tube 3d which is the electrode facing the sample 5. So, conventionally, for example,
The deposits S on the anode tube 3d are removed using a cutting tool such as a reamer that is a rotary precision polishing tool. But,
In order to set all the samples 5 so that they can be analyzed under the same conditions, the above-mentioned step of removing the attached matter S is required every time the analysis of the sample 5 is completed, which causes a reduction in the efficiency of the analysis.

In addition, in the above-described step of removing the deposit S by the cutting tool, it is necessary to polish the anode tube 3d so as not to damage the anode tube 3d. Therefore, it is difficult to completely remove the deposit S. Therefore, even if the attached matter S is removed every time the analysis of the sample 5 is completed, it is impossible to eliminate the measurement error due to the influence of the attached matter S. If a resin component or the like adheres to the surface of the anode tube 3d facing the sample 5, the resin component or the like easily emits light again in the next analysis regardless of whether or not polishing is performed. Further, since the deposits S are mechanically removed by polishing with a cutting tool, the anode tube 3d is likely to be roughened by polishing. When the next analysis of the sample 5 is started in this state, the glow discharge space becomes vacuum. Before being drawn, the components in the atmosphere, such as O (oxygen) and N (nitrogen), tend to adhere to the rough surface of the anode tube 3d, and these components may also cause measurement errors.

FIG. 6 shows an example of actual measurement of the adverse effect of the above-mentioned deposit S. The figure shows a sample in which a deposited film mainly composed of Co (cobalt) and a protective film mainly composed of C are sequentially formed on the surface of a resin film (for example, PET film) mainly composed of C (carbon). The analysis results show that at the sputtering time (T) of the Co layer forming the surface layer portion, a considerable amount of C not contained in this Co layer was detected. This is because C in the resin film sputtered last in the last analysis of the sample 5 remains on the surface of the anode tube 3d facing the sample 5 and emits light in the next analysis of the Co layer of the sample 5. It indicates that
This causes a measurement error.

Accordingly, the present invention provides a method for accurately emitting light without being affected by the deposits on the anode tube during the previous analysis of the sample, while greatly reducing the number of deposit removal steps relative to the number of sample analyzes. An object of the present invention is to provide a glow discharge emission spectroscopy method capable of analysis.

[0009]

To achieve the above object, a glow discharge optical emission spectroscopy method according to the present invention comprises the steps of: placing a sample in a glow discharge space of a glow discharge tube at a position facing an anode tube; In a glow discharge optical emission spectroscopy method for performing emission analysis while sputtering a sample by discharging between the anode tube and the sample, the glow discharge emission spectroscopy is included in the measurement target after the analysis of one sample and before the analysis of the next sample. A step of sputtering a coating material made of a non-element is performed.

[0010]

[Operation and Effect] Each time the analysis of one sample is completed,
A coating material that does not contain the element to be measured in the next sample is placed in the glow discharge tube so as to face the anode tube as in the sample analysis, and the anode tube is analyzed as in the sample analysis. The material is sputtered by a discharge between the material and the coating material. The substance scattered from the material due to the spattering adheres to the surface of the deposit on the anode tube generated in the previous sample analysis to form a coating layer. When the next sample is attached to the glow discharge tube to generate glow discharge, even if the coating layer emits light together with the sample under analysis, this coating layer is not included in the measurement target of the sample under analysis. Since it is composed of elements, it does not adversely affect the analysis of the sample. The sample and the deposit due to the resin component analyzed last time emit little light because they are covered with the coating layer and are not exposed.
Therefore, the emission analysis can be accurately performed without being affected by the attachment during the previous analysis of the sample.

As described above, the deposits adhering to the surface of the anode tube facing the sample 5 during the analysis of the sample are covered with the coating layer after the analysis and do not adversely affect the analysis of the next sample. Need not be removed each time one sample is analyzed. In other words, since the deposits on the anode tube may be removed before they are deposited to such an extent that the glow discharge inside the anode tube and the emission of the sample are adversely affected, for example,
It is only necessary to remove the sample by polishing with a cutting tool every time the analysis of the sample is completed a predetermined number of times. Therefore, the number of times of removing the deposit can be significantly reduced. Also, since the coating layer is formed by sputtering the coating material after removing the deposits by the cutting tool, the rough surface is not exposed by the polishing of the cutting tool. The problem that an error is caused by N can be solved, and the adverse effect due to the attachment of a contaminant such as abrasion powder of the material of the cutting tool can also be excluded. In addition, by attaching the coating material to the automatic loading machine, it is possible to easily and quickly attach and detach the sample to and from the glow discharge tube after analyzing the sample, thereby reducing the efficiency of the sample analysis. Nor.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the whole of an analyzer provided for carrying out the glow discharge emission spectroscopy method according to the present invention. In this analyzer, light L emitted from a grim glow discharge tube 1 that generates light having a wavelength specific to an element by sputtering using glow discharge and transmitted through a window plate 13 enters a spectroscope 15. The spectroscope 15 includes an entrance slit 14, a diffraction grating 16 that diffracts the light L incident from the entrance slit 14 at different diffraction angles according to the wavelength, and an exit slit 17 that passes the diffracted light.
And a photomultiplier tube 18 for measuring the intensity of the diffracted light.

FIG. 2 shows an example of a grim glow discharge tube 1 and a mechanism attached thereto in the analyzer of FIG. In the figure, a glow discharge tube 1 is the same as that of FIG.
An automatic loading device 20 for automatically attaching and detaching the glow discharge tube 1 to and from the glow discharge tube 1 and a polishing device 30 for removing the deposit S on the anode tube 3d are provided. The sample 5 to be analyzed is placed, for example, by manual operation so as to face the anode tube 3d, and then attached to the support block 2 by a pressing device (not shown) with the sealing member 6 interposed therebetween.

The automatic loading device 20 is mounted such that the base of the arm 26 is slidable on the guide shaft 22 and rotates integrally. The arm is reciprocated in the direction of arrow A along the guide shaft 22 by a linear drive mechanism (not shown). The arm 22 rotates integrally with the guide shaft 22 rotated by a rotation drive source 28 such as a pulse motor, for example, and
The position is alternatively changed to the position indicated by the chain line. A material holder 29 that supports the coating material 10 by a method such as vacuum suction is provided on one surface of the end portion of the arm 26 on the glow discharge tube 1 side. Material holder 2
Numeral 9 allows the position of the arm 26 to be adjusted within a small range in the direction of arrow B along the length direction thereof.

On the other hand, the polishing apparatus 30 includes a polishing machine 31 for rotating a cutting tool 34 rotatably supported by a rotary drive source 32 such as a motor. This polishing machine 31
It is reciprocated in the direction of arrow A along a guide member (not shown) by driving of a linear drive device (not shown). Polishing machine 31
When the cutting tool 34 moves forward toward the glow discharge tube 1,
Is inserted into the anode tube 3d while rotating to remove the deposits, and then the polishing tool 31 is moved backward from the glow discharge tube 1 so that the cutting tool 34 allows the sample 5 and the coating material 10 to be attached and detached. It retreats to the illustrated position that does not interfere. As the linear motion mechanism of the sander 31, for example, a well-known mechanism such as a rack and a pinion is used.

Next, the analysis method of the present invention using the above configuration will be described with reference to FIG. 3 showing the steps. First, at the start of the analysis, the arm 26 of the automatic loading device 20 is used.
2 is retracted to the position shown by the two-dot chain line in FIG. 2 and the polishing machine 31 of the polishing apparatus 30 is retracted to the position shown in FIG. 2, and the sample 5 is manually operated as shown in FIG. And is attached to the support block 2 by a pressing device (not shown) with the seal member 6 interposed therebetween.

In the state shown in FIG. 3A, when a high voltage of several hundred to several thousand volts is applied between the anode block 3 and the support block 2 by the power supply unit 9, the anode tube 3d and the sample 5 A glow discharge is generated in the gas, and cations of argon are generated. The generated Ar ions collide with the analysis surface 5a of the sample 5, which is a cathode, and sputter the analysis surface 5a. As a result, the atoms that have been knocked out and separated from the analysis surface 5a of the sample 5 are excited by Ar ions or electrons, and emit element-specific light when returning to the ground state again. This light L passes through the window plate 13 and travels through the entrance slit 14 in FIG. 1 to the diffraction grating 16 of the spectroscope 15.
The diffraction grating 16 diffracts light having a predetermined wavelength, and makes the light enter a photomultiplier tube 18 through an exit slit 17. The photomultiplier tube 18 measures the intensity of the incident light.
After the completion of this analysis, sample 5
The substance scattered from the air adheres to the inner wall surface and the distal end surface of the anode tube 3d, and becomes the adhered matter S.

When the analysis of one sample 5 is completed, the sample 5
When the start switch (not shown) of the automatic loading device 20 is turned on after manually removing from the glow discharge tube 1, the arm 26 is integrally formed with the guide shaft 22 which is rotated by the drive of the rotary drive source 28. 2 is rotated from the two-dot chain line position to the solid line position, and the coating material 10 attached to the distal end of the arm 26 via the material holder 29 is positioned so as to face the anode tube 3 d of the glow discharge tube 1. . The linear drive mechanism of the automatic loading device 20 is activated by detecting the end of the rotation of the rotary drive source 28, and the arm 22 slides on the guide shaft 22 as shown in FIG.
Is moved to the left, and eventually, as shown in FIG.
The coating material 10 is pressed against the support block 2 via the sealing member 6 in an arrangement facing the anode tube 3d. In this state, a high voltage of several hundred to several thousand volts is applied between the anode block 3 and the support block 2 by the power supply unit 9 for a predetermined time (for example, 30 seconds) as in the case of the analysis of the sample 5 described above.
By applying a voltage, a glow discharge is generated between the anode tube 3d and the coating material 10, and the coating material 10 is sputtered.

The substance scattered from the coating material 10 by this sputtering adheres to the surface of the deposit S by the sample 5 in a thin film form, and as shown in FIG.
A coating layer CS covering almost the entire surface of the deposit S is formed. Here, as the coating material 10, a substance made of an element not included in the measurement target of the sample 5 to be analyzed next is used. Further, as the coating material 10, it is desirable to use a material that is difficult to thermally decompose after adhering to the anode tube 3d.

When the formation of the coating layer CS is completed, the arm 22 is moved rightward in FIG. 2 in the automatic loading device 20 to separate the material 10 from the glow discharge tube 1, and thereafter the arm 26 is moved. It is rotated and retracted to the position shown by the two-dot chain line in FIG. Subsequently, FIG.
The analysis step of the sample 5 shown in (a) and the formation step of the coating layer CS using the coating material 10 shown in FIG.

As described above, after the analysis of the sample 5 is completed and before the analysis of the next sample 5, the coating layer CS that covers the surface of the deposit S on the anode tube 3d is formed. When performing, even if the coating layer CS emits light due to glow discharge, the attachment S of the previous sample 5 covered with the coating layer CS suppresses the light emission, so that the same element as the sample 5 under analysis is used. It is possible to prevent the occurrence of a measurement error due to the sputtered attached matter S.

FIG. 4 shows a sample 5 described in the measurement results of FIG.
In the analysis of the above, actual measurement results when the coating layer CS is formed using a silicon wafer as a pure substance as the coating material 10 are shown. At the sputtering time (T) of the Co layer, the amount of C detected is remarkably reduced as is apparent from comparison with FIG. This indicates that C of the deposit S by the resin film that was sputtered last in the last analysis of the sample 5 was not sputtered because it was covered by the coating layer CS.
FIG. 6 shows that the deposit S cannot be completely removed by polishing with a cutting tool. In this way, there is no influence of the deposit S at the time of the previous analysis of the sample 5.

As described above, since the element of the attached matter S from the sample 5 is not detected at the time of the next analysis of the sample 5, it is not necessary to remove the attached matter S every time the analysis of the sample 5 is completed as in the related art. That is, the deposit S including the coating layer CS is
It may be removed before depositing to such an extent that the glow discharge inside the anode tube 3d or the light emission of the sample 5 is adversely affected. Therefore, for example, the polishing apparatus 30 is set to start when the count value of the number of times of analysis of the sample 5 reaches a predetermined value,
3A and the coating layer C shown in FIG.
The polishing step shown in FIG. 3C is performed between the step of forming S. In this polishing step, the polishing machine 31 moves in the direction of the glow discharge tube 1 along the guide member 36, and removes the deposit S including the coating layer CS by the cutting tool 34 inserted into the anode tube 3d while rotating. . The cutting tool 34 has a step in the middle, and grinds the inner wall surface of the anode tube 3d at the tip, and grinds the tip at the step.

At this time, even if the surface of the anode tube 3d is roughened by the polishing of the cutting tool 34 as in the conventional case, this surface is covered with the coating layer CS. And no adverse effects from pollutant elements. Therefore, in the surface layer data, more accurate emission analysis can be performed than in the case where the conventional cleaning means by polishing of a cutting tool is used.

Since the coating material 10 can be easily and quickly attached to and detached from the glow discharge tube after the analysis of the sample 5 using the automatic loading device 20 as in the above embodiment, There is no reduction in efficiency.
Further, in the above embodiment, since the position of the material holder 29 can be adjusted in the length direction of the arm 26, the coating material can be effectively used by sequentially changing the portions where the coating material is to be sputtered. The interval of replacement with the automatic loading device 20 can be lengthened, and from this point, the efficiency of sample analysis can be improved.

In the above embodiment, the automatic loading device 20
The coating material 10 was loaded into the glow discharge tube by the above method, but this loading may be performed manually.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an analyzer according to an embodiment of the analysis method of the present invention.

FIG. 2 is a cross-sectional view showing one example of a Grim glow discharge tube in the analyzer.

FIG. 3 is a sectional view showing the steps of the analysis method of the present invention.
(A) shows a sample analysis step, (b) shows a coating layer formation step, and (c) shows a deposit removal step.

FIG. 4 is a diagram showing an example of an actual measurement result in the embodiment.

FIG. 5 is a sectional view showing a glow discharge tube in a conventional analyzer.

FIG. 6 is a diagram showing an example of an actual measurement result by the above device.

[Explanation of symbols]

1 ... glow discharge tube, 3 ... anode tube, 5 ... sample, 10 ... material for coating.

Claims (1)

(57) [Claims] 1. A glow discharge optical emission spectrometer for arranging a sample at a position facing an anode tube in a glow discharge space of a glow discharge tube and performing emission analysis while sputtering the sample by discharge between the anode tube and the sample. A method for glow discharge emission spectroscopy, comprising, after analyzing one sample and before analyzing the next sample, sputtering a coating material made of an element not included in the measurement object.