JPS63127155A - Thin film analyzer - Google Patents

Abstract

PURPOSE:To analyze the characteristic of a specimen such as MW or the like by a method wherein the molecule on the surface of the thin film specimen is ionized by an excited species and the data relating to the quantity of the electron of ion generated on said surface as the result of ionization is obtained from each electrode. CONSTITUTION:When high voltage is applied between a cylindrical electrode 8 and a needle electrode 10 from a power source 12 to generate corona discharge, exciting argon Ar* (excited species) is formed. When this excited species contacts with an org. thin film specimen 3, the specimen 3 is ionized by the energy possessed by the excited species. The electron thus formed can be detected by various modes. For example, in a mode wherein negative voltage Va is applied between collector electrodes 2, 4 to measure the current Ia flowing to an intermediate electrode 7, the electron flying out from the surface of the specimen can be detected by the electrode 7 because of the negative voltage applied to the electrodes 2, 4. At this time, the Va-Ia curve of the voltage Va and the current Ia shows a saturation characteristic. Since the saturation current Is thereof corresponds to the average MW of the substance present on the surface of the specimen, when the saturation current is calculated, the average MW of the surface of the specimen can be calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film analyzer suitable for use in analyzing nR films.

[Prior Art] Recently, research on membranes has been progressing in various technical fields including biotechnology.

In these studies, it is important to investigate the physical properties and characteristics of thin films, and analytical tools such as ion microanalyzers, Auger electron spectrometers, X-ray photoelectron spectrometers, and infrared spectrophotometers are used for this purpose. Traditionally used.

[Problems to be solved by the invention] Such devices that have been used in the past have large device configurations, are expensive, and require samples to be placed in a vacuum or sample pretreatment. It was inevitable that the measurements would be time-consuming.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a novel thin film analyzer that can obtain information regarding the physical properties, characteristics, or thickness of a thin film with a relatively simple configuration.

[Means for Solving the Problems] In order to achieve this object, the thin film analyzer of the present invention includes means for exciting a carrier gas by corona discharge to generate excited species of the carrier gas, and a passageway for the excited species. A collector electrode arranged, a thin film sample held on a surface of the collector electrode that the excited species contacts, and an intermediate electrode arranged facing the thin film sample between the excited species generating means and the collector electrode. It is characterized by being configured.

[Operation] When the excited species hits the thin film sample held on the collector electrode, the molecules on the aM'J surface are ionized by the energy of the excited species, and the ions and electrons are generated on the surface. By detecting this ion or electron mother using an intermediate electrode or a collector electrode, information regarding the physical properties, characteristics, or thickness of the thin film can be obtained.

Hereinafter, one embodiment of the present invention will be explained in detail based on the drawings.

[Example] FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention.

In the figure, 1 is a shield electrode at ground potential, 2 is a collector electrode, 3 is an organic thin film sample held on the surface of the collector electrode, 4 is a second collector electrode arranged so as to be in contact with the peripheral surface of the thin film 3, 5 is an insulator for maintaining insulation between each electrode, 6 is a discharge tube for creating excited species, and 7 is a mesh-like intermediate electrode arranged between the discharge tube 6 and the thin film sample 3.

The discharge tube 6 is composed of a cylindrical electrode 8, a vibrator 9 that guides a carrier gas such as argon into the cylindrical electrode 8, a needle electrode 10, and an insulating plug 11.
When a high voltage is applied between zero and a corona discharge is generated, excited argon (excited species) is generated. Although this excited species has no electric charge, it has relatively large energy and flows from the open end of the cylindrical electrode 8 toward the thin film sample 3 along with the flow of the carrier gas. When this excited species comes into contact with the organic thin film sample (Org), the thin film sample is ionized by the energy of the excited species according to the following formula.

Ar* +Qrg-+Org+ +e-+, A
r.(1) The e- generated in this way can be detected in various modes as described below.

[Mode △: Negative voltage Va is applied to the collector 1M12.4, and the current (a) flowing through the electrode 7 is measured] In this mode, the electrons e ejected from the sample surface due to the negative voltage applied to the collector electrodes 2 and 4 - can be detected by the electrode 7. At this time, the va -1a curve of the voltage Va and the current 1a shows a saturation characteristic as shown in Fig. 2.The saturation current 1s is the average of the substances present on the sample surface. Since it corresponds to the molecular weight, it is possible to determine the average molecular weight of the sample surface by determining the saturation current.

In order to do this, first calculate the relationship between the average molecular weight and saturation current using several compounds whose molecules are known as thin film samples, and then calculate the average molecular weight from the saturation current of the unknown thin film sample based on that relationship. Just ask.

[Mode C: Applying a negative voltage vb to the collector electrode 2 and measuring the current 1b flowing through the snow field 41 In this mode, the electrons accumulated on the surface of the thin film sample can be measured. Vb
The -1b curve exhibits saturation characteristics similar to the Va-1a curve of mode A, and the average molecular weight on the sample surface can be determined in the same manner.

[Mode C: A positive voltage VC is applied to the collector electrode 4 and the electrode 7, and the current [C flowing to the collector electrode 2] is measured. In this mode C, the positive voltage applied to the electrode 4.7 causes the collector electrode 2 to An ionic current 1c corresponding to the current flows. The value of this current 1c should be approximately the same as the electron currents Ia and Ib in modes A and B, but the shape of the Vc-1c curve changes slightly depending on the film thickness of the sample. Therefore, by examining changes in the Vc-1c curves of several samples whose film thicknesses are known in advance, it is possible to determine the film thickness of the sample from the VC-IC curve of the sample whose film thickness is unknown.

[Mode C: A negative voltage Vd is applied to the collector electrode 4 and the electrode 7, and the current 1d flowing to the collector electrode 2 is measured1. In this mode D, the electrons e generated on the surface of the a film sample
- of the current that passes through the thin film sample and reaches the back surface flows into the collector electrode 2 and is detected as the current Id. By comparing this current 1d with the current 1b measured in mode B (information regarding all electrons generated on the sample surface), information regarding the electronic conductivity of the thin film can be obtained.

In either mode, if a floating amplifier is used to measure the current and a voltage suitable for collection is applied in accordance with the charge to be measured, the total current can be measured more completely.

The voltage applied to the electrode 7 and the collector electrode 4 may be a constant voltage, but it may be a rectangular wave, a sine wave, or a pulse of O←→+V (or -V), and the voltage applied to the electrode 7 and the collector electrode 4 may be a rectangular wave, a sine wave, or a pulse. By measuring the deviation, more accurate information on film thickness and film properties can be obtained.

FIG. 3 shows another embodiment of the invention, in which a second mesh electrode 13 is further arranged between the collector electrode 4 and the electrode 7.

In this embodiment, in addition to the modes A to D described in the embodiment of FIG. 1, the following measurements can be performed.

That is, when a positive voltage is applied to the electrode 13 and a small amount of ethanol (such as acetone is also acceptable) is hung on this electrode, the ethanol is ionized by the excited species Ar ratio according to the following formula, and SH+ is generated. It will be done.

Ar rate + χS → SH ÷ + S (S - H) - + Ar Nail... (2) When this SH+ reaches the thin film sample surface, if the proton affinity of sample material M is greater than that of ethanol S, 5TnH By the proton transfer reaction between ÷ and sample M, protonated molecular ions (MH", M2R, etc.) of the sample are generated on the sample surface according to the following formula.

81-1"+yM → M, H++...to η... (3) If an appropriate positive voltage is applied to electrode 7.13.4 and the current flowing to electrode 2 is measured, the current generated on the sample surface can be determined. Information corresponding to the protonated sample molecular ions can be obtained, and information regarding the proton conductivity of the thin film sample can be obtained.

Note that by applying a negative voltage to the electrode 13 and measuring the current flowing through the electrode 2, negative ions generated on the sample surface can be detected.

Furthermore, the ion current accumulated on the sample surface can also be measured using the electrode 4.

FIG. 4 shows still another embodiment of the present invention. In this embodiment, the intermediate electrode 7 is not a mesh electrode as in the embodiment of FIG. 1, but is arranged so that its tip is close to the surface of the thin film sample. A needle-like electrode is used.

The tip of this needle-like electrode has a sharp curvature of, for example, about 0.1 .mu.m, and is covered with an insulating coating except for the tip. The distance between this tip and the sample surface is variable, and the tip is held by a moving mechanism that can two-dimensionally move on the sample surface while maintaining a set distance. Note that the needle-like electrode may be configured to change only the distance from the sample surface so that the sample is moved two-dimensionally.

Then, the measurement is carried out using the A-
This is done in exactly the same way in each mode. The electrode 4 provides information on the total current, and the electrode 7 provides information on only the micro area on the sample surface where the tip is located, and the measurement area can be arbitrarily selected by moving the electrode 7 or the sample appropriately. be able to.

Furthermore, a rectangular wave voltage that changes as 0←→10■ or +V←→-■ may be applied to the electrode 4, and the time change or phase shift of the current flowing through the electrode 7 may be measured.

Although this is true for all modes, negative ions in equation (2) can also be measured by reversing the polarity of the voltage applied to the electrodes.

When measuring each current, the currents flowing into two electrodes, such as electrode 7 and electrode 4, electrode 7 and electrode 2, or electrode 4 and electrode 2, should be determined and compared at the same time. However, it is preferable in that it is possible to more accurately identify differences in the behavior of ions and electrons, the surface current of the membrane resistor 1, etc.

In each example, it is also possible to provide a sample heating means by embedding a heater in the electrode 1, change the temperature of the sample, and examine the change in current. , melting point, etc.).

[Effects] As detailed above, according to the present invention, molecules on the surface of a thin film sample are directly or indirectly ionized by excited species,
As a result, a thin film analyzer with a simple configuration that obtains information on the amount of electrons or ions generated on the surface from each electrode can analyze sample characteristics such as film thickness, electron conductivity, and proton conductivity. Realized.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of one embodiment of the present invention, Fig. 2 is a diagram showing an example of voltage-current characteristics, and Figs. 3 and 4 are schematic diagrams showing other embodiments of the present invention. It is a diagram. 1: Shield electrode 2, 4: Collector electrode 3: Thin film sample 5: Insulator

Claims (3)

[Claims] (1) A means for exciting a carrier gas by corona discharge to generate excited species of the carrier gas, a collector electrode disposed in a path of the excited species, and a thin film sample held on the surface of the collector electrode that is in contact with the excited species. and an intermediate electrode arranged facing the thin film sample between the excited species generating means and the collector electrode. (2) The thin film analyzer according to claim 1, wherein the intermediate electrode is a mesh electrode. (3) The thin film analyzer according to claim 1, wherein the intermediate electrode is a needle-like electrode, and the tip of the needle-like electrode is placed close to the thin film sample.