JPH065287B2 - Low speed electronic measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a technique for correcting a discharge rate, that is, a reference point, of a device that measures low-speed electrons by utilizing a gas discharge in the atmosphere.

(Prior Art) For detection of photoelectrons, thermoelectrons, and exoelectrons (hereinafter referred to as low-speed electrons) emitted from the surface of a sample, an anode is placed inside a cathode made of a conductive container opened to the atmosphere through an opening,
Further, the first and second grids are arranged in the opening 1a, a voltage of about 3.4 KV is applied between the cathode and the anode, and the first and second grid electrodes are always 100 V and 80 V, respectively. A low speed electronic measuring device with a voltage applied is used.

In this device, when the low-speed electrons emitted from the sample surface pass through the space and enter the cathode through the opening, the low-speed electrons trigger the discharge in the anode, and the anode outputs a pulse signal. While operating the counting means by this pulse signal, the potential of the first grid electrode is raised to prevent the development of discharge, and at the same time, the second grid electrode is lowered to a negative potential to neutralize the cations generated during the discharge. The number of low-speed electrons generated is measured while repeating the process of summing and returning to the original state.

By the way, since the low-speed electron detector is connected to the atmosphere through the opening, as shown by the solid line in FIGS. However, there is a disadvantage that the discharge condition is directly changed and the count rate with respect to the same anode voltage is greatly changed, resulting in a large measurement error in the measurement result.

Needless to say, such a problem is solved by detecting atmospheric conditions using a pressure sensor, a temperature sensor, a humidity sensor, etc., and adjusting the anode voltage based on the detection result, but various sensors are required. Not only that, the control amount must be determined in consideration of the difference in the degree of influence that each parameter that governs atmospheric conditions has on discharge conditions and the interrelationship between these parameters, which requires a special calculation means. Cause problems.

In order to solve such a problem, a method of correcting using a detector similar to the physical quantity detector is also a conventional means as seen in JP-A-51-131379, but an equivalent physical quantity detector is used. There is a problem that it is necessary and costly.

(Purpose) The present invention has been made in view of such a problem, and its object is to use a correction detector that is as inexpensive as possible to detect low-speed electronic signals that fluctuate due to a plurality of events. It is an object of the present invention to provide a slow electron detector capable of correcting the reference point of the detector.

(Structure) Therefore, details of the present invention will be described below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes a container-shaped cathode which is opened to the atmosphere through an opening 1a formed in the lower portion, and which is unequal in the internal space. A low-speed electron detector is configured by arranging an anode 2 that forms an electric field, a first grid electrode 3 that controls discharge, and a second pole electrode 4 in a vertical relationship. The anode 2 is connected to the first voltage variable high voltage generator 5 and is configured to generate an electric field sufficient to generate a discharge when low-speed electrons flow.
It is also connected to an amplifier 7 via a DC blocking capacitor 6.

The first grid electrode 3 is connected to the first pulse generator 8 and is constantly applied with a voltage of about 100 V, and with the output of the pulse signal from the amplifier 7, a voltage of about 400 V that continues Te for a certain time. The grid electrode 4 is connected to the second pulse generator 9 so that a voltage of about 80 V is normally applied, and a voltage of about −30 V for maintaining Te for a certain period of time is applied by the pulse signal output from the amplifier 7. Has been done. 10 is an atmospheric condition detector for detecting the atmospheric condition,
Reference numeral 11 in the figure is a container-shaped cathode communicating with the atmosphere through an opening 11a, and an anode 12 is arranged in the center of the space, while a grid electrode is conductively connected to the cathode near the opening 11a. 14 is provided to block the inflow of electrons from the outside. A second variable voltage high voltage generator 15 scans the output voltage and stops the voltage scanning when the output from the second counter 16 reaches a preset count rate. The scanning is stopped. The output voltage Vd is output to the control circuit 17 described later. 17
Is the second voltage variable high voltage generator 1 in the control circuit described above.
The voltage Vd of 5 is used as a parameter to cause the first variable high voltage generator 5 to output a voltage for causing the anode 2 to generate a constant level of discharge. In addition, reference numeral 1 in the drawing
Reference numeral 8 denotes a first counter that counts pulse signals from the low-speed electron detector, and 19 denotes a display device that processes the output from the counter 18 and converts it into a count rate or the like for display.
Indicate respective DC blocking capacitors.

Next, the operation of the apparatus configured as described above will be described based on the waveform diagram shown in FIG.

It is assumed that the current atmospheric conditions are those shown by II in FIG.

When the sample S is placed below the cathode opening 1a and the apparatus is operated, the slow electrons emitted from the surface of the sample S receive the electric field formed by the anode 2 of the slow electron detector and the second grid electrode 4 Then, it passes through the first grid electrode 3 sequentially and is attracted to the anode 2. In this way, low-speed electrons
When reaching the vicinity of, the electrons are rapidly accelerated by the action of the strong electric field distributed in the vicinity of the anode 2, and ionize the surrounding atmosphere to cause discharge. As a result, the anode 2 becomes
Causes a sudden drop in potential. This potential drop becomes a pulse signal through the DC blocking capacitor 6, is amplified by the amplifier 7, is input to the counter 18, and is displayed on the display device 19 as the generation frequency and number of low-speed electrons.

On the other hand, this pulse signal is input to the first and second pulse generators 8 and 9, and the first pulse generator 8 superimposes and outputs a pulse having a voltage of, for example, 300 V and a time width Te to output the first grid electrode 3 The potential is raised to 400 V to extinguish the discharge. Also, by outputting a pulse from the second pulse generator 9,
The potential of the second grid electrode 4 is lowered to −30 V with respect to the cathode 1, and the cations generated in the cathode 1 by the above discharge are extinguished. When the time Te has elapsed, the pulse output from the first and second pulse generators 8 and 9 is stopped, and the measuring device returns to the initial state and waits for the next inflow of low-speed electrons.

At the same time as the measurement of the low-speed electrons, the atmospheric condition detector 10
Receives the voltage scan of the second voltage variable high voltage generator 15, and performs self-sustaining discharge at the count rate corresponding to the state shown in II of FIG. 6 (a) and (b), that is, the current atmospheric state. To do. In this case, since the atmospheric state does not change, the count rate set is reached every time the voltage Vd is reached. Therefore, the control circuit 17 maintains the output voltage V ₀ from the first variable voltage high voltage generator 5.

In such a state, atmospheric conditions such as atmospheric pressure, temperature, and humidity change, and conditions related to discharge such as electron mobility near the anode 2 change, and the discharge condition changes as shown in FIG.
It is assumed that the state shown in III of (b), that is, the count rate has decreased.

The atmospheric condition detector 10 is subjected to voltage scanning by the second voltage variable type high voltage generator 15, and is shown in FIG. 6 (a) (b).
The state indicated by III is reached, and the previous voltage Vd cannot cause self-sustaining discharge equivalent to the previous count rate, and at the time when scanning is performed to a voltage higher than this, the second counter 16 outputs The counting rate reaches the set level. At this point, the second variable voltage high voltage generator 15 stops the voltage scanning and outputs the voltage Vd ′ to the control circuit 17.
Needless to say, this voltage Vd 'represents the atmospheric condition after the fluctuation. The control circuit 10 controls the voltage Vd '.
In response to this, the output voltage of the first voltage variable high voltage generator 5 is shifted to the high voltage side by ΔV to adjust the discharge condition.
As a result, the discharge condition is returned to the condition before the atmospheric condition change, that is, the same condition as II shown in FIGS. 5 (a) and 5 (b), and thereafter, the counting rate for one low-speed electron, that is, the detection sensitivity. Detects slow electrons without causing a change.

Thereafter, such voltage adjustment is performed every time the atmospheric condition changes to maintain a constant count rate for one low-speed electron.

FIG. 3 shows a second embodiment of the present invention, in which reference numeral 21 is an anode arranged inside a container-shaped cathode 1, and a conductor wire is formed in a loop shape, which will be described later. It is configured to receive electric power from the anode temperature control circuit 22 and raise the temperature by Joule heat. This anode 21 is connected to a high voltage generator 23 so as to generate an electric field sufficient to generate a discharge when low-speed electrons flow in, and is also connected to an amplifier 7 via a DC blocking capacitor 6. There is. Two
2 is the above-mentioned anode temperature control circuit, which is the atmospheric condition detector 10
It is configured to supply heating power so that the anode 21 reaches a temperature at which a constant level of discharge is generated, with the voltage having a count rate of the second counter 16 connected to the parameter set to a preset value as a parameter.

Next, the operation of the apparatus thus configured will be described based on the waveform chart shown in FIG.

The atmospheric conditions such as atmospheric pressure, temperature, and humidity change, and the conditions related to the discharge such as the electron mobility near the anode 21 change, and the discharge condition is indicated by II in FIG. 5 (a) (b). It is assumed that the state has changed to the state shown in FIG. 3, that is, the state in which the count rate decreases.

The atmospheric condition detector 10 includes a variable voltage high voltage generator 24.
It is subjected to voltage scanning by, but III in Fig. 6 (a) (b).
In the state shown by, the previous voltage Vd cannot cause self-sustaining discharge with the same count rate as the previous time, and therefore, when the scanning is performed up to the high voltage Vd ', the second counter 16 outputs The counting rate reaches the set level. At this point, the variable voltage high voltage generator 24 stops the voltage scanning and outputs this voltage Vd ′ to the anode temperature control circuit 22. Needless to say, this voltage Vd 'represents the atmospheric condition after the fluctuation. The anode temperature control circuit 22 is
The heating power to the anode 21 of the low-speed electron detector is increased by using this voltage Vd 'as a parameter to increase the temperature of the anode 21 by ΔT.
Only shift to the high temperature side. As a result, the temperature of the gas near the anode 21 rises and the mobility of electrons increases, and the discharge condition is the state before the atmospheric condition change, that is, FIG.
The condition is returned to the condition indicated by II in (b), and thereafter, low-speed electrons are detected without changing the count rate for one low-speed electron, that is, the detection sensitivity.

In the embodiment described above, the voltage scanning of the atmospheric condition detector is performed from the low voltage side, but based on the anode voltage at the time when the counting rate is reduced to the set value by scanning from the high voltage side. The discharge condition of the low speed electron detector may be controlled. Further, in the above-mentioned embodiment, the detection of the discharge state in the atmospheric state detector is performed based on the change of the count rate, but it can be detected from the peak value of the pulse signal from the amplifier 7 or the magnitude of the anode load current. Needless to say. Further, in the above-described embodiment, the anode temperature is controlled by directly energizing the anode, but the same effect can be obtained even if a heater is arranged near the anode to indirectly heat.

Further, in the above-described embodiment, the state in which the intrusion of low-speed electrons is blocked, that is, the state in which the low-speed electrons are zero is used as the calibration reference, but an object that emits a known amount of energy rays such as electron beams is used, and this energy ray is used. Needless to say, even if the counting rate based on is adjusted so as to be constant, the same effect is obtained.

(Effect) As described above, in order to detect the atmospheric condition,
A container-shaped cathode having an inflow port communicating with the atmosphere, an anode disposed inside the cathode, a grid electrode disposed at the inflow port to prevent electrons from entering, and at least a discharge to the anode Is used to control the voltage and temperature of the anode of the low-speed electron detector by using an atmospheric condition detector equipped with a second voltage variable type high voltage generating means for outputting a voltage sufficient to generate It is possible to accurately control the discharge state affected by a plurality of events such as humidity, humidity, and atmospheric pressure by a signal from one detector.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention, and FIG.
FIG. 4 is a waveform diagram showing the operation of the same device, FIG. 3 is a block diagram of the device showing another embodiment of the present invention, FIG. 4 is a waveform diagram showing the operation of the device of FIG. 3, and FIG. Is a characteristic diagram showing the relationship between the atmospheric condition and the count rate in the low-speed electron detector, and FIG. 6 is a characteristic diagram showing the relationship between the atmospheric condition and the count rate in the atmospheric condition detector. 1 ... Cathode 2, 21 ... Anode 3, 4 ... Lattice electrode 10 ... Atmospheric condition detector 11 ... Cathode 12 ... Anode 14 ... Lattice electrode

Claims (2)

[Claims] 1. A container-shaped cathode, which communicates with the atmosphere and is provided with an inflow port for low-speed electrons, and a first voltage variable type which is arranged inside the cathode and which outputs at least a voltage sufficient to cause discharge. An anode to which a voltage from a high voltage generating means is applied, and a low-speed electron detector provided with a grid electrode that allows the inflow of electrons at all times and blocks the inflow of electrons for a certain period after the anode is discharged. A container-shaped cathode having an inflow port communicating with the atmosphere, and a voltage from a second voltage variable high-voltage generating unit that is disposed inside the cathode and outputs a voltage sufficient to cause at least discharge. An atmospheric condition detector provided with an applied anode and a grid electrode disposed at the inlet to constantly block electrons from entering, and the output voltage of the second voltage variable high voltage generating means is changed in one direction. Let the discharge of the anode of the atmospheric condition detector By the output voltage condition is changed, the low-speed electronic measuring and control means for controlling the output voltage of the first voltage-variable high-voltage generating means. 2. A container-shaped cathode in which an inflow port for low-speed electrons communicating with the atmosphere is formed, and a voltage which is disposed inside the cathode and which is temperature controlled by a heating means and at least causes discharge. An anode to which a voltage from the first voltage variable high voltage generating means for outputting is applied, and a grid electrode which permits the inflow of electrons at all times and blocks the inflow of electrons for a certain period after the anode is discharged. A low-speed electron detector provided with a container, a container-shaped cathode having an inflow port communicating with the atmosphere, and a second voltage variable type disposed inside the cathode and outputting a voltage sufficient to cause at least discharge. An anode to which a voltage from the high voltage generating means is applied, an atmospheric condition detector provided at the inflow port and having a lattice electrode for always blocking electrons from entering, and an output of the second voltage variable high voltage generating means Change the voltage in one direction By the output voltage discharge state changes in the anode of the state detector, the low-speed electronic measuring device comprising a temperature control means for controlling the temperature of the anode of the low-speed electron detector.