JPH02156145A - Measurement of hydrogen in thin film - Google Patents

Abstract

PURPOSE:To achieve a higher measuring accuracy by specifying energy and an angle of incidence of charged particles incident on a thin film made of amorphous carbon or the like. CONSTITUTION:Charged particles radiated at a slit 1 are made incident on a thin film 2 at such a small angle that atom C and atom H bounce by an elastic scattering thereof. The atom C fails to reach a detector 3 losing energy with a Mylar filter 4 and hence, the atom H alone reaches the detector 3. So, energy of the atom H is analyzed with the detector 3 to measure an electric charge of the atom H in terms of energy. Then, an energy spectrum is determined as indicating a relationship between the energy of the atom H and an energy-wise number of the atom H to measure a depth-wise distribution of the atom H in the thin film 2 and an absolute amount of the atom H based thereon. Here, the energy of charged particles and the angle of incidence are set at 6-8 Mev and 6-10 deg. respectively. This is because a higher measuring accuracy is attained with small depth-wise resolutions at 6 MeV in energy while the atom H fails to bounce below the value. The atom H also fails to bounce below 6 deg. in angle of incidence.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for measuring the depth distribution and absolute amount of hydrogen atoms (H atoms) in a thin film such as an amorphous carbon film.

B1 Summary of the Invention The present invention is a method for measuring )-1 atoms in a thin film using the hydrogen recoil method, which is a method of nuclear elastic scattering. The measurement accuracy was improved by setting the angle to 6 to 8 M e V and 6 to 10 degrees, respectively.

C. Conventional technology Amorphous carphone (a-C:1-1) and amorphous silicon carbide (a-SiC:H) have properties such as high hardness, excellent translucency, and high resistivity, and are applicable to a wide range of fields. is expected to be a substance.

These amorphous thin films contain a large amount of hydrogen during the film manufacturing process, and these hydrogen have a large effect on optical or electrical properties. That is, in an amorphous structure, the bonds between atoms are not regular and there are twists, etc., resulting in the formation of unbonded groups. When these form a shallow energy level, the electrical resistance decreases or the optical gap narrows and the transparency decreases, but these phenomena can be prevented by hydrogen compensating for the unbonded groups. can. However, if the hydrogen content increases more than necessary,
A sparse film with low density is formed. Furthermore, when these films are stacked to form a device, the diffusion of atoms at the stacked interface can be predicted to some extent based on the distribution of hydrogen. Therefore, it is important to measure the absolute hydrogen loss in the film, including the distribution in the depth direction, but there are very few methods for quantitatively measuring hydrogen, and generally methods using nuclear elastic scattering or nuclear reactions are used. will be adopted.

D9 Problems to be Solved by the Invention However, in these two methods, if the sample contains a large amount of hydrogen, hydrogen may escape due to ion beam damage during the measurement, so it is necessary to continue irradiating the nucleus with the beam while gradually changing the energy. Methods using reactions are unsuitable. On the other hand, the method using nuclear elastic scattering has the disadvantage of poor depth resolution.

An object of the present invention is to provide a method that uses nuclear elastic scattering, but can obtain high depth resolution and improve measurement accuracy.

80 Means for Solving the Problems The present invention provides a method for measuring H atoms in a thin film using the hydrogen recoil method, which is a method of nuclear elastic scattering. It is characterized by being 6 to 8 M e V and 6 to 10°, respectively.

F Example FIG. 1 is a diagram showing a measuring device used in the hydrogen recoil method.

In this method, if, for example, C″″″ ions emitted from the slit I are made to enter the film 2 at a small incidence fQ,
C3' ions collide with C atoms and H atoms in the thin film, causing elastic scattering, and the C atoms and H atoms recoil. 3 is a detector, and a mylar filter 4 is installed in front of this detector 3. The recoil atoms lose energy in the Mylar filter 4 and do not reach the detector 3. Therefore, only H atoms reach the detector 3, and the I-
The energy of one atom is analyzed and the charge ff1(C) of the H atom is measured for each energy. Here, this amount of charge is Q,
■Energy of one atom is E, scattering cross section of H atom is Vl
l, the solid angle of the detector is Ω, 1-(the atomic density of the atom is NH
, the thickness of the thin film is L, the integral value Y of energy yield is expressed by the following equation (1).

Y-V, (E, f(θ))×ΩXQXNHX t=-(
+) V 11(E, r(θ))×Ω of the above formula (1)
are constants specific to the measurement system, and can be found through calculations, but
■An even simpler method is to use a standard sample. ×Ω
There is a way to determine. This time, we will focus on materials with known hydrogen content, such as Mylar (C+oHgo 4) and Kapton (C,
,H,. Measure organic films such as O, N, ) as standard samples and substitute the results into equation (1) to calculate V +
+XΩ was calculated.

The integral value Y of the yield corresponds to the number of H atoms, and is obtained from the charge 1 of the H atoms measured in the detection "?53. Therefore, Y is determined for each energy of the atom, and the relationship between the energy and Y is An energy spectrum showing the relationship is obtained as shown in FIG.

In this energy spectrum, the spectrum width along the horizontal axis corresponds to the depth of the thin film, and the yield value (integral value) Y along the vertical axis corresponds to the number of H atoms, so this spectrum corresponds to the depth of the thin film of H atoms. Shows directional distribution. The area of the spectrum is a value corresponding to the absolute value of 411 H atoms, and by determining this area, the density of 11 atoms in the thin film can be determined. However, in reality, the energy spectrum of a sample whose density is known accurately is measured in advance.
The density of atoms is determined by comparing their spectra.

Next, referring to the depth resolution, the depth resolution R is expressed by the following equation (2).

R=(δE/ΔE)×L (2) where δE is the energy width at the rise of the spectrum, ΔE is the total spectrum width, and t is the thickness of the thin film. This depth resolution corresponds to the measurement accuracy when measuring the depth direction distribution, and the smaller the depth resolution, that is, the smaller δE, the higher the measurement accuracy.

The main cause of δE is C incident on the thin film.
3. Errors caused by ions, errors caused by H atoms emitted from the O thin film, geometric errors caused by the finite width of the slit placed on the θ detector surface, and errors caused in the 0-mil filter. This is represented by four points.

Then, a computer takes into account these factors from ■ to 0, and determines the charge depending on the energy of the charged particles incident on the thin film. 1
The relationship between the incident angle of i particles (01 shown in FIG. 1) and the depth resolution was determined, and the graph shown in FIG. 3 was obtained. Solid lines A and ~A3 in Fig. 3 indicate the energy of charged particles at 8 M e V.
The results are the values at the surface, 500 people, and 1500 people, respectively.

Moreover, dotted lines 81 to r33 indicate the energy of charged particles as 12
The results are M e V, and the surface, 500 people,
The value is at a depth of 1500 people. The values indicated by circles in FIG. 3 are the values obtained by actually measuring the energy spectrum and calculating the depth resolution based on that spectrum.

Based on this result, in the present invention, when applying the hydrogen recoil method, the energy and incident angle of charged particles are adjusted to 6 to 8 Me, respectively.
V16~10", thereby improving the resolution. For example, at a size of 6 M e V, the depth resolution is a very small value of 105 people. Note that the energy of charged particles is Below 6 M e V, H atoms do not recoil sufficiently from the thin film. Also, when the incident angle is below 6°, the direction of incidence of charged particles becomes approximately parallel to the thin film, and I'' atoms do not recoil sufficiently. do not.

In the above experiment, the scattering angle (θ in FIG. 1) was measured at 20°, but it is preferable that the scattering angle θ is 18 to 22°. Also, as a filter, the thickness is 6μ~201tx
It is preferable to use a Mylar filter.

FIG. 4 shows that C content<r Eft
The figure shows an energy spectrum measured for a laminated film in which a layer with a large amount of carbon is sandwiched between two layers with a small number of layers, and it can be seen that the rise of the spectrum is good. From this figure, it was observed that the film with a large amount of C-containing hl contained a large amount of hydrogen, and no diffusion occurred at the interface.

G1 Effects of the Invention According to the present invention, it is possible to elegantly quantify hydrogen using ordinary analysis means, and since the depth resolution is small, the distribution of hydrogen in the depth direction can be measured with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a measuring device used in the present invention, FIGS. 2 and 4 are energy spectrum diagrams, and FIG. 3 is a graph showing the relationship between depth resolution and incident angle. 1...Slit, 2...Thin film, 3...Pressure detector, 4...
·filter. Other 2 people Figure 1 Song 1 constant * BJj O's first stage Figure 2 Energy +:-space vector Figure 4 O (Mourning guard Lugi (MeV)

Claims (1)

[Claims] (1) Charged particles are incident on a thin film at a small angle of incidence, hydrogen atoms recoil by elastic scattering are detected, and an energy spectrum showing the relationship between the energy of the hydrogen atoms and the number of hydrogen atoms for each energy is obtained. In the method of measuring the depth distribution of hydrogen atoms and the absolute amount of hydrogen atoms in a thin film based on this, the energy and incidence angle of charged particles are set to 6 to 8 MeV, respectively.
A method for measuring hydrogen in a thin film, characterized in that the angle is 6 to 10 degrees.