JP2004281333A - Electronic spectrometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic spectrometer in which a high precision analysis result is obtained without variations depending on the operators and, by improving the operability and automating the throttle operation, chemical state mapping of the test piece becomes possible. <P>SOLUTION: The electron spectrometer comprises an irradiation means for irradiating primary striae on the test piece, a field stop constructed so as to change the aperture, a first electron lens for focusing the electrons emitted from the test piece on the field stop, a preparation means for preparing an aperture of the field stop according to the magnifying power of the first electron lens and the analysis aperture of the test piece, a second electron lens for focusing the electrons that have passed the field stop on the entrance slit of an analyzer by decelerating, the analyzer for selecting the electrons that have passed the entrance slit by their energy, and a detecting means for detecting the electrons selected by the analyzer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron spectrometer such as a photoelectron spectrometer.
[0002]
2. Description of the Related Art A photoelectron spectrometer is a device that irradiates a sample surface with X-rays and analyzes electrons emitted from the sample by the irradiation with a photoelectron spectrometer to obtain an energy spectrum. These electrons are called photoelectrons because they come out when exposed to light. By analyzing the energy spectrum obtained at this time, the element on the sample surface and the chemical state of the element can be known.
[0003]
In a photoelectron spectrometer, a field limiting aperture and an angle limiting aperture are provided in an input lens group for focusing photoelectrons emitted from a sample surface on an entrance slit of an energy analyzer, and a lens magnification for focusing photoelectrons on the field limiting aperture. The size (analysis diameter) of the analysis area on the sample surface is defined by the diameter of the field-of-view limiting aperture and the angle-limiting aperture that limits the opening angle of the photoelectrons taken in. At this time, as the field-of-view limiting and the angle-limiting aperture, a fixed-type aperture having a plurality of apertures of a fixed aperture is used, or an iris-type aperture having an aperture mechanism capable of continuously varying the aperture of the iris is used. Has been done. Each of the apertures is manually adjusted according to the setting conditions.
[0004]
However, in an apparatus employing a combination of fixed diaphragms, the analysis region to be analyzed is limited to the prepared diaphragm diameter type. In the case of an iris-type diaphragm that is continuously variable, the aperture diameter may be slightly different depending on the operator. Particularly, when an analysis region of several tens of micrometers is set, the influence on the analysis result is large. Further, it is complicated to change the aperture every time according to the size of the analysis diameter and the lens magnification, and a desired analysis result cannot be obtained unless the aperture is changed. As a conventional technique, there is an X-ray fluorescence analyzer provided with a diaphragm moving mechanism by automatic control (for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-6-308060
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to obtain a high-precision analysis result without variation among operators and to improve operability. Another object of the present invention is to perform chemical state mapping on a sample by automating the operation of the aperture.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an irradiation means for irradiating a sample with a primary ray, a field-of-view limiting aperture whose aperture diameter can be changed, and an electron emitted from the sample by the primary beam irradiation on the field-of-view limiting aperture. A first electron lens to form an image, a field-limiting aperture setting means for setting an aperture of the field-limiting aperture according to an analysis diameter of the sample, and a deceleration of the electrons passing through the field-limiting aperture. A second electron lens for forming an image on the entrance slit of the analyzer, an analyzer that sorts the electrons that have passed through the entrance slit by the energy thereof, and a detection unit that detects the electrons that are sorted by the analyzer, It is characterized by having.
[0008]
According to a second aspect of the present invention, there is provided an angle-limiting aperture having a variable aperture diameter disposed between the field-of-view limiting aperture and the second electron lens, and an aperture diameter of the angle-limiting aperture according to an analysis diameter of the sample. Angle limiting aperture opening diameter setting means for setting
[0009]
A third aspect of the present invention is characterized in that a deflection unit for deflecting the electrons is provided.
[0010]
A fourth aspect of the present invention is characterized in that a chemical state map generating means for generating a chemical state map of the sample based on a detection result of the detecting means corresponding to scanning by the deflecting means is provided.
[0011]
According to a fifth aspect of the present invention, there is provided a sample moving unit on which the sample is placed and movable in a two-dimensional direction, a sample moving amount setting unit for setting an arbitrary moving amount of the sample moving unit,
It is characterized by having.
[0012]
A sixth aspect of the present invention is characterized in that a chemical state map generating means for generating a chemical state map of the sample based on a detection result of the detecting means corresponding to the movement by the sample moving means is provided.
[0013]
【Example】
Hereinafter, the configuration of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the photoelectron spectroscopy apparatus of the present invention. An analysis chamber 101 is evacuated to an ultra-high vacuum by an exhaust device (not shown). The degree of vacuum in the analysis chamber 101 is monitored by a vacuum gauge (not shown), and the detection output of the vacuum gauge is supplied to a host computer 116. The X-ray source 102 is attached to the analysis room 101, and is an excitation light source for irradiating the sample 123 arranged in the analysis room 101 with soft X-rays (primary rays) to excite photoelectrons. The X-ray source 102 is connected to a host computer 116 via an X-ray source power supply (not shown). The sample 123 is held on the sample stage 104 via a sample holder. The sample stage 104 is attached to the analysis room 101, and can be moved in the X, Y and Z directions by adjusting the sample stage position adjusting mechanism 103. The magnetic field lens 105 is a magnetic field type electron lens, and is arranged below the sample 123.
[0014]
The electron spectrometer is attached to the analysis room 101, and includes an input lens 124, an analyzer 110 for performing energy analysis of photoelectrons from the input lens 124, and a detector 111 for detecting photoelectrons selected by the analyzer 110. ing. The input lens 124 includes, in order from the sample side, a ground electrode 125-1, a main magnification control lens 106, a ground electrode 125-2, an auxiliary magnification control lens 107, a ground electrode 125-3, an electrostatic imaging lens 108, and a ground electrode. 125-4 and a deceleration lens 109. Each of these electrodes is arranged at a predetermined distance from an adjacent electrode. Each electron lens uses an electrostatic electron lens having a cylindrical electrode, and the magnification can be changed within a certain range by changing the applied voltage.
[0015]
The input lens 124 is provided with a circular field limiting aperture 112 and a circular angle limiting aperture 113. The field-of-view limiting aperture 112 is provided to limit an area for taking in photoelectrons generated on the sample surface, and the aperture limits an analysis area on the sample. The field limiting aperture 112 is disposed between the auxiliary magnification control lens 107 and the imaging lens 108 so as to partition the inside of the cylinder of the input lens 124. As shown in FIG. 3, the center of the opening of the field limiting aperture 112 is located on the optical axis of the input lens 124. An iris diaphragm 501 having a movable diaphragm blade 502 as shown in FIG. 5 is used as the field limiting diaphragm 112, and a field limiting diaphragm opening diameter adjusting mechanism 113 computer-controlled by a diaphragm control unit 119 is provided with a servo with a rotary encoder. By driving with a motor, the aperture diameter of the field-of-view limiting aperture 112 can be changed continuously. A stepping motor may be used instead of the servo motor. The angle limiting aperture 113 is arranged between the field limiting aperture 112 and the electrostatic imaging lens 108 so as to partition the inside of the input lens 124. The angle limiting aperture 113 is provided to limit the take-in angle of the photoelectrons that have passed through the field limiting aperture 112. The angle limiting aperture 113 reduces blur caused by the spherical aberration of the lens system, and performs analysis on the sample. The accuracy of the area can be compensated. Similarly to the field limiting aperture 112, the center of the opening of the angle limiting aperture 113 is located on the optical axis of the input lens 124, and the iris 501 is used to adjust the iris by the angle limiting aperture adjusting mechanism 115 to adjust the aperture. Can be changed continuously.
[0016]
The analyzer 110 is installed following the input lens 124, and has an entrance slit 126 at the entrance and a photoelectron detector 111 at the exit. Electrodes are arranged in the vertical direction of the analyzer. By changing the applied voltage, adjustment can be made so that only photoelectrons of an arbitrary speed reach the photoelectron detector 111.
[0017]
The magnetic lens 108, the input lens 124, the apertures 112 and 113, the analyzer 110, and the photoelectron detector 111 are respectively formed by an imaging lens control unit 118, an input lens control unit 120, an aperture control unit 119, an analyzer control unit 121, and a photoelectron detection. And is controlled by the host computer 116 via the control interface 117.
[0018]
The configuration of each unit has been described above. Next, the operation will be described with reference to FIG. First, the operator sets the analysis diameter of the sample by selecting a desired analysis diameter from the condition setting screen of the host computer 116. At this time, the analysis diameter may be set by directly inputting a numerical value. The host computer 116 uses the measurement control software to calculate the optimal magnification of the electron lens with a small amount of aberration and the aperture diameter corresponding to the photoelectrons from the region of the set analysis diameter. Lens magnification is the magnification at which the analysis diameter is projected onto the field limiting aperture. In other words, since the range of magnification that can be set for the electronic lens is limited, the host computer 116 selects a combination of the electronic lens and the lens magnification for measurement at the set analysis diameter from a predefined electron lens control table. I do. FIG. 6 is an example of a table showing combinations of electronic lenses. When the analysis diameter is 2 mm, the magnetic field lens is not used, and the lens magnification becomes 5 times by the combination of the main magnification control lens and the auxiliary magnification control lens. A voltage to be applied to the main magnification control lens 106, the auxiliary magnification control lens 107, and the electrostatic imaging lens 109 is determined by a lens setting voltage table (not shown). Based on the aperture diameter determined by the lens magnification, the rotation angle of the aperture adjustment mechanism is calculated from a table (not shown) showing the relationship between the aperture of each aperture and the rotation angle of the aperture adjustment mechanism. The host computer 116 sets the rotation angle of the aperture driving mechanism in the aperture control unit 119. The aperture control unit 119 drives the aperture adjustment mechanisms 114 and 115 with a servomotor equipped with a rotary encoder so that the rotation angle becomes the set rotation angle.
[0019]
At this time, since the aperture is computer-controlled according to the analysis diameter, there is no slight variation in the aperture diameter by the operator, and a highly accurate result can be obtained. In addition, the automation of the diaphragm does not forget the operation of the diaphragm and does not involve a complicated operation, so that the analysis can be performed efficiently.
[0020]
The host computer 116 sets data calculated under predetermined analysis conditions in the photoelectron detection control unit 122 and the analyzer control unit 121. Further, the host computer 116 sets the voltage of the deceleration lens 109 to the input lens control unit 120 such that the photoelectrons that have passed through the field limiting aperture 112 and the angle limiting aperture 113 appropriately decelerate.
[0021]
When the evacuation of the analysis chamber 101 is completed, the host computer 116 sends an X-ray irradiation signal for performing X-ray irradiation on the sample 123 using the X-ray source 102 to an X-ray source power supply (not shown). When the sample 123 is irradiated with X-rays, photoelectrons are emitted from the sample surface. The electron beam generated by the photoelectrons is imaged on the field limiting aperture 112 by the main magnification control lens 106 and the auxiliary magnification control lens 107. That is, even if the aperture diameter of the field limiting aperture 112 is set to be considerably small, many photoelectrons pass through the aperture of the field limiting aperture 112 and are taken into the analyzer 110. Therefore, a spectrum having a good S / N ratio can be obtained in a short time. Since the first electronic lens in this embodiment is composed of a two-stage lens of the main magnification control lens 106 and the auxiliary magnification control lens 107, changing the voltage applied to each of the electronic lenses makes the first electronic lens more variable. It can handle a wide range of lens magnifications. When the lens magnification is changed, the diameter at which the photoelectrons image on the field-of-view limiting aperture 112 is different, so the aperture diameter of the field-of-view limiting aperture 112 is also changed.
[0022]
The photoelectrons that have passed through the aperture of the field-limiting aperture 112 and further passed through the aperture of the angle-limiting aperture 113 are imaged on the entrance slit 31 of the analyzer 110 by the electrostatic imaging lens 108, and thus pass through the aperture. All the photoelectrons that have entered enter the analyzer 110. The photoelectrons are appropriately decelerated by the deceleration lens 109. When the voltage applied to the deceleration lens 109 is changed according to the analysis energy of the analyzer 110, the voltage applied to the electrostatic imaging lens 108 is changed so that photoelectrons are imaged on the entrance slit 31.
[0023]
FIG. 3 schematically shows a light beam diagram relating to the photoelectron capture of the input lens 124.
[0024]
The photoelectrons that have passed through the entrance slit 126 are subjected to energy spectroscopy by the analyzer 110, and only photoelectrons at a predetermined speed reach the photoelectron detector 111. If the inside of the alanizer needs to be exhausted during the analysis, it is exhausted by an exhaust device (not shown) connected to the analyzer 110. The detector 111 that has detected the photoelectrons converts the detected photoelectrons into an electric signal and outputs the electric signal, which is taken into the host computer 116 via a pulse measurement system (not shown). The host computer 116 generates a photoelectron spectrum from the captured signal and displays the spectrum on a screen of a display device. Since the chemical property of a substance depends on the bonding state of atoms, the chemical property can be known if the bonding state of the substance can be known from the photoelectron spectrum.
[0025]
In the above example, the magnetic lens 105 is turned off. However, the magnetic lens 105 may be used to form an image of the photoelectrons generated from the sample on the field-of-view limiting aperture 112. In this case, the main magnification control lens 106 is turned off, and photoelectrons generated from the sample are imaged on the field-of-view limiting aperture 112 by the magnetic field lens 105 and the auxiliary magnification control lens 107. The magnetic lens 105 is often used when the analysis diameter is less than 1 mm.
[0026]
Next, another embodiment will be described. FIG. 2 is obtained by adding a sample stage adjustment mechanism control unit 127 and a polarizer 128 to FIG. The deflector is disposed near the ground electrode 125-1 and deflects the electric field in the X and Y directions parallel to the sample surface. In this case, a first deflector for changing the electric field to scan so as to capture a micro-analysis region of the sample that is not on the center axis of the electron lens, and the scanned electron beam is incident on the field limiting aperture without making an angle. A second deflector for deflecting the electron lens toward the central axis may be provided to deflect in two stages. FIG. 4 is a schematic ray diagram relating to photoelectron capture. If the aperture diameter of the field-of-view limiting aperture 112 is set to a size corresponding to the analysis of a small area and the electric field is scanned two-dimensionally by a deflector, a large area on the sample is analyzed first, and then the large area is analyzed. Photoelectrons generated from each point (each minute area) in the area can be sequentially taken into the alanizer 110 and detected by the detector 111. Then, the host computer 116 writes a signal from the detector 111 into the internal memory in accordance with the scanning by the deflector 128, creates a chemical state map for a large area of the sample surface based on the stored information, and displays the map. Display on the screen.
[0027]
Further, another embodiment will be described. This embodiment is characterized in that a sample stage position adjusting mechanism that can be adjusted in the X and Y directions by computer control in FIG. 2 is provided. The sample stage position adjusting mechanism uses an XY table, and is driven by a servo motor or a stepping motor that is computer-controlled by the sample stage position adjusting mechanism control unit. As in the previous embodiment, the aperture diameter of the field limiting aperture 112 is set to a size corresponding to the micro area analysis, and the sample stage position adjustment mechanism is moved. Photoelectrons generated from each point (each minute area) can be sequentially taken into the alanizer 110 and detected by the detector 111. The host computer 116 writes a signal from the detector 111 in the internal memory in accordance with the movement of the sample stage position adjusting mechanism, creates a chemical state map for a large area of the sample surface based on the stored information, and displays the map. Display on the screen. In this case, the sample is analyzed with a relatively wide analysis diameter, and when the chemical state of an element or a specific element required for the analysis of the sample to be measured is detected, the analysis diameter is used to analyze how it is analyzed. May be reduced for chemical state mapping. Since the sample stage position adjusting mechanism has a large moving amount, it can perform a wider range of chemical state mapping than that using a deflector, but the accuracy using a deflector is higher.
[0028]
Note that the present invention is not limited to the above example. In the embodiment, the sample is irradiated with soft X-rays. However, a vacuum ultraviolet light source (helium resonance ray source) may be incorporated in the apparatus instead of the soft X-ray source, and the sample may be irradiated with vacuum ultraviolet light. In this manner, by applying a low-energy primary beam to the sample, a change in the chemical state of the sample surface due to the gas reaction treatment can be obtained from the obtained spectrum of the valence band.
[0029]
Further, the present invention can be applied to an electron spectroscope such as an Auger electron spectroscope.
[0030]
【The invention's effect】
As described above, in the present invention, by controlling the aperture diameter of the aperture defining the analysis diameter by a computer, there is no variation in the analysis diameter by the operator, and the analysis diameter is always reproduced within the range of the mechanical accuracy. And operability is improved.
[0031]
Further, since the aperture diameter of the aperture defining the analysis diameter is controlled by a computer, automation becomes possible, and chemical state mapping of the sample surface can be performed.
[Brief description of the drawings]
FIG. 1 is a photoelectron spectroscopy apparatus according to the present invention.
FIG. 2 is a photoelectron spectroscopy apparatus for performing chemical state mapping according to the present invention.
FIG. 3 is a schematic diagram of light rays related to photoelectron capture according to the present invention.
FIG. 4 is a schematic diagram of light beams related to deflected photoelectron capture according to the present invention.
FIG. 5 is a plan view of an aperture using the iris (A in FIG. 1).
FIG. 6 is an electronic lens control table.
Reference Signs List 101 analysis room, 102 X-ray source, 103 sample stage position adjustment mechanism, 104 sample stage, 105 magnetic field lens, 106 main magnification control lens, 107 auxiliary magnification control lens, 108 electrostatic imaging lens, 109 deceleration lens, 110 analyzer , 111 photoelectron detector, 112 field limiting aperture, 113 angle limiting aperture, 114 field limiting aperture adjusting mechanism, 115 angle limiting aperture adjusting mechanism, 116 host computer, 117 control interface, 118 magnetic field lens control unit, 119 aperture control unit, 120 Input lens control unit, 121 analyzer, 122 photoelectron detector control unit, 123 sample, 124 input lens, 125 ground lens, 126 entrance slit, 127 sample stage adjustment mechanism control unit, 128 deflector 30 Sample, 302 main magnification control lens, 303 auxiliary magnification control lens, 304 field limiting aperture, 305 angle limiting aperture, 306 imaging lens, 307 deceleration lens, 308 entrance slit, 309 lens center axis, 310 deflector 501 iris diaphragm, 502 Variable aperture blade

Claims (6)

Irradiating means for irradiating the sample with a primary beam;
A field-of-view aperture stop with a variable aperture diameter,
A first electron lens that forms an image of electrons emitted from the sample by the primary beam irradiation on the field-of-view limiting aperture;
Field-of-view limiting aperture opening diameter setting means for setting the aperture of the field-limiting aperture according to the analysis diameter of the sample,
A second electron lens for decelerating the electrons passing through the field-of-view limiting aperture to form an image on the entrance slit of the analyzer;
An analyzer that sorts the electrons that have passed through the entrance slit by their energy,
Detecting means for detecting the electrons selected by the analyzer,
Electron spectroscopy device equipped with. An angle-limiting aperture that can change an aperture diameter and is disposed between the field-of-view limiting aperture and the second electronic lens;
Angle limiting aperture opening diameter setting means for setting the aperture diameter of the angle limiting aperture according to the analysis diameter of the sample,
The electron spectroscopy device according to claim 1, further comprising: 3. The electron spectroscopy apparatus according to claim 1, further comprising a deflecting unit for deflecting the electrons. 4. The electron spectroscopy apparatus according to claim 3, further comprising: a chemical state map generating unit configured to generate a chemical state map of the sample based on a detection result of the detection unit corresponding to the scanning by the deflection unit. A sample moving unit on which the sample is mounted and movable in a two-dimensional direction; a sample moving amount setting unit for setting an arbitrary moving amount of the sample moving unit;
The electron spectrometer according to any one of claims 1 to 3, further comprising: 7. The electron spectroscopy apparatus according to claim 6, further comprising: a chemical state map generating unit configured to generate a chemical state map of the sample based on a detection result of the detecting unit corresponding to the movement by the sample moving unit.

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