JPH0637564Y2 - Neutral particle scattering analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial field of application The present invention irradiates a sample with neutral particles, and detects neutral particles and ions scattered and emitted by the sample to detect the crystal of the sample. The present invention relates to a neutral particle scattering analyzer for analyzing a structure.

(B) Conventional Technology When performing elemental analysis, structural analysis, etc. of a sample by applying the scattering analysis method, usually charged particles such as ions and electron beams are used as an excitation source. For example, in an ion scattering analyzer (ISS), the structure of the sample is analyzed by irradiating the sample with ions and separating the scattered ions from the sample with a magnetic field mass spectrometer.

(C) Problems to be solved by the invention When the analysis sample is a conductor such as a metal, there is no problem in using charged particles, but when analyzing an insulator, these charged particles are used as a sample. There is a problem of charge accumulation. For example, in the case where it is desired to analyze the crystal structure of an insulating film formed on a semiconductor substrate, when the charge is accumulated in the sample, the trajectory of the charged particles is bent, and accurate analysis cannot be performed.

In order to avoid this, conventionally, the surface of the sample is coated with a conductor film, or an electron shower is applied to prevent charge accumulation.

However, in the former method, when it is desired to observe the structure of the pole surface, the information of the coated conductor film is simultaneously input, so that the true surface state cannot be analyzed. Further, in the latter method, each time charge is accumulated, the analysis is interrupted midway and a neutralization operation is required, so that efficient analysis cannot be performed.

(D) Means for Solving the Problems The present invention has been made in view of such circumstances, and provides a means for accurately performing structural analysis on the sample surface of the insulator.

Therefore, in the present invention, a chopping deflector that chops the ions output from the ion source at a high frequency, a pulse generator that gives a chopping pulse for ion deflection to the chopping deflector, and an ion that passes through the chopping deflector A neutralizer that neutralizes, a time-of-flight energy analyzer that separates the neutral particles emitted from the neutralizer that are scattered and emitted by the sample, and the neutral particles that have been separated into energy. A neutral particle dispersion analyzer was configured with a detector for detection and a time measuring device for inputting a chopping pulse of a pulse generator as a start pulse and a detection output of the detector as a stop pulse.

(E) Action In the above configuration, the ion beam from the ion source is chopped by the chopping deflector in synchronization with the chopping pulse, the ions passing through this chopping deflector are neutralized by the neutralizer, and then collide with the sample. Let In this case, charge accumulation does not occur because the excitation source of the sample is neutral particles. Then, the neutral particles scattered by the sample are time-separated by the time-of-flight energy analyzer and detected by the detector. Since the time-of-flight energy analyzer separates energy by the difference in the time of flight, neutral particles can also be analyzed. Since the chopping pulse of the pulse generator is input to the time measuring device as the start pulse and the detection output from the detector is input as the stop pulse, the time measuring device receives the start pulse and then outputs the stop pulse next. Measure the time until input. Then, the required energy spectrum is obtained by correlating the measured value as the energy intensity and the time frequency as the count value.

(F) Example FIG. 1 is a block diagram of a neutral particle scattering analyzer. In the figure, 1 is the whole neutral particle dispersion analyzer, and 2 is
An ion source that takes out He gas etc. by ionizing the electron beam,
Reference numeral 4 is a chopping deflector for chopping the ions output from the ion source 2 at a high frequency, and 6 is a pulse generator for applying a chopping pulse for ion deflection to the chopping deflector 4. In other words, from the pulse generator 6,
A pulse having a frequency of KHz is generated, ion passage is allowed only when the chopping pulse is applied to the chopping deflector 4, and the ion travels straight on the optical axis A. When the chopping pulse is not applied, the ion is deflected. It is received and removed from the optical axis A.

Reference numeral 8 is an electrostatic lens that converges the ions that have passed through the chopping deflector 4, and 10 is a neutralizer that neutralizes the ions.
The neutralizer 10 neutralizes the ions by, for example, irradiating the ions with an electron beam. Reference numeral 12 is an ion removing deflector for deflecting and removing the ions remaining without being sufficiently neutralized by the neutralizer 10, and 14 is an insulator sample.

Reference numeral 16 is a time-of-flight energy analyzer that separates the neutral particles and ions emitted by the neutral particles scattered by the sample 14, and clearly distinguishes the flight times of the neutral particles and ions emitted from the sample 14. Electrostatic acceleration tube for
18, a detector 24 comprising a microchannel plate 20 and an anode 22. 26 is a pre-stage amplifier that amplifies the detection output of the detector 24, and 30 is a time measuring device that inputs the chopping pulse of the pulse generator 6 as a start pulse and the detection output of the detector 22 as a stop pulse. In this example, A time-to-digital converter is used. Reference numeral 32 is a computer for performing data processing such as measuring time data measured by the time digital converter 30 to obtain an energy spectrum, and 34 is a CRT display for displaying the analysis result of the sample 14.

Next, an operation when the insulator sample 14 is analyzed by applying the neutral particle dispersion analyzer 1 having the above-described configuration will be described.

The ion beam emitted from the ion source 2 is first chopped by the chopping deflector 4. That is, only when the chopping pulse is applied from the pulse generator 6 to the chopping deflector 4, the passage of the ions is allowed and the ions travel straight on the optical axis A. When the chopping pulse is not applied, the ions are deflected. Off the optical axis A. The chopping pulse from the pulse generator 6 is simultaneously applied to the time digital converter 30 as a start pulse.

Ions traveling straight through the chopping deflector 4 are converged by the electrostatic lens 8 and introduced into the neutralizer 10 to be neutralized. The neutral particles emitted from the neutralizer 10 are made to collide with the sample 14. Ions that have not been neutralized by the neutralizer 10 are
It is deflected by the ion removing deflector 12 and deviates from the optical axis A, and the sample 14 is not irradiated. In the sample 14, the scattered neutral particles and the ions generated at that time are introduced into the time-of-flight energy analyzer 16. In order to distinguish the neutral particles and the ions from each other, the electrostatic accelerating tube 18 gives a difference in flight time, and then the neutral particles and the ions are separated into energy and detected by the detector 24. Then, the detection output of the detector 24 is applied as a stop pulse to the time-digital converter 30 via the pre-stage amplifier 26. Therefore, as shown in FIG. 3, the time-to-digital converter 30 receives the ions from the detector 24 after the chopping pulse from the pulse generator 6 is added as a start pulse (see FIG. 2 (a)). Each time t ₁ , t ₂ , t ₃ (see FIG. 2B) until each detection output of the neutral particles is input as a stop pulse is converted into digital data and output. Then, this digital data is sent to the computer 32 at the next stage. The computer 32 stores the time measurement value as the scattering intensity and the frequency at which the same flight time is obtained as the count value in association with each other. Then, as shown in FIG. 3, the required energy spectrum can be obtained by obtaining the correlation with the scattering intensity on the horizontal axis and the count value on the vertical axis. This energy spectrum information is displayed on the CRT display 34.

If the chopping operation of the chopping deflector 4 is stopped and the neutralizer 10 is removed, normal ion scattering analysis can be performed.

(G) Effect of the Invention According to the present invention, charge accumulation does not occur when an insulator is analyzed, so that the structure analysis of the sample surface of the insulator can be performed accurately. Further, since neutral particles are made to collide with the sample unlike conventional ions, excellent effects such as obtaining information on new structural analysis based on the result of interaction between atoms are exhibited.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram of a neutral particle scattering analyzer, FIG. 2 is a time chart showing the relationship between start pulse and stop pulse of a time measuring instrument, and FIG. Is a characteristic diagram of an energy spectrum finally obtained. DESCRIPTION OF SYMBOLS 1 ... Neutral particle scattering analyzer, 2 ... Ion source, 4 ... Chopping deflector, 6 ... Pulse generator, 10 ... Neutralizer, 14 ...
Sample, 16 ... Time-of-flight energy analyzer, 24 ... Detector, 30 ... Time measuring instrument (time digital converter).

Claims (1)

[Scope of utility model registration request] 1. A chopping deflector for chopping ions output from an ion source at a high frequency, a pulse generator for applying a chopping pulse for ion deflection to the chopping deflector, and an ion passing through the chopping deflector. Neutralizer that neutralizes, neutral particles from this neutralizer are time-of-flight energy analyzer that separates the neutral particles that are scattered and emitted by the sample into energy, and the neutral particles that have been separated into energy. A neutral particle scattering analyzer, comprising: a detector for detecting; and a time measuring device for inputting a chopping pulse of the pulse generator as a start pulse and a detection output of the detector as a stop pulse, respectively.