JP2976305B2 - Amorphous monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of growing an amorphous film such as SiO ₂ or Ni on a substrate, The present invention relates to an amorphous monitoring device that notifies a state in a short time.

(Prior Art) FIG. 3 is a block diagram showing a conventional amorphous monitoring apparatus of this kind. Sample 22 includes SiO ₂ grown on the substrate and
It is an amorphous thin film of Ni or the like. Although this amorphous thin film is growing in a vacuum chamber, an amorphous thin film growth apparatus is not shown in this figure for simplicity. The electron gun 21 irradiates the surface of the sample 22 with an electron beam at a low angle. The electron beam applied to sample 22
The light is scattered by 22 and forms a diffraction pattern on the sensor 23.
The sensor 23 is a TV camera and has a diffraction pattern intensity F
(S) is output. The microcomputer 24 calculates a scattering intensity function I (s) from the diffraction pattern intensity F (s). The host computer 25 uses its scattering intensity function I
A radial distribution function J is obtained by performing a Fourier transform on (s).
(R) is obtained, and the distance between bonds (r ₁ , r ₂ ,..., R ₁ ) and the bond coordination number (n ₁ , n ₂ ,...) Are determined from the peak separation of the radial distribution function J (r). , n ₁ ). The display 26 receives the radial distribution function J (r) from the host computer 25, and this J
(R) is displayed on the screen as a graph. The amorphous state was evaluated by a human based on the distance between bonds and the number of bond coordinations.

(Problems to be Solved by the Invention) In the conventional amorphous monitoring device described above, the host computer 25 calculates the radial distribution function J (r), separates the peak of the J (r), and The inter-bond distance and bond coordination number are determined based on the peak. Thereafter, it was necessary for a human to evaluate the amorphous state based on the distance between bonds, the number of bond coordination, and the like. As described above, the evaluation of the amorphous state using the conventional apparatus requires human judgment on the way and requires complicated calculations. Therefore, using a conventional device,
It took several minutes to evaluate the amorphous state of 22. Samples in the process of manufacturing amorphous thin films
Since No. 22 grew at a rate of about 0.4 ° / sec, it was not possible to obtain an amorphous thin film in an optimal state by using a conventional apparatus that required several minutes for evaluation. As described above, the conventional amorphous monitoring apparatus has a problem to be solved regarding the evaluation time of the amorphous state.

(Means for Solving the Problems) A means provided by the present invention for solving the above-mentioned problems is to irradiate an amorphous film with an electron beam or X-ray, and to scatter the electron beam or X-rays scattered by the amorphous film. Forming a diffraction pattern on the sensor, and analyzing the intensity of the diffraction pattern output from the sensor to determine the degree of order of the atomic arrangement in the amorphous film,
An amorphous monitoring device that outputs this degree as data representing the degree of amorphization of the amorphous film, and the root mean square of a correlation function obtained by Fourier transform of the diffraction pattern intensity is used as the degree of orderness. It is characterized by the following.

(Effect) If the radial distribution function J (r) is defined as the average density of atoms contained in a spherical shell having a thickness dr located at a distance r from one atom, an amorphous nearly amorphous the film, in a small range of r number + Å, J (r) is the approximately ^{J (r) = 4πr 2 ρ} o + rG (r) ... (1). Here, ρ _o is the average density of the film, and rG (r) is a correlation function. In a completely amorphous becomes ^{J (r) = 4πr 2 ρ} o. Therefore, rG (r) is a function representing the deviation from a completely amorphous state, and the root mean square (R, M, S) α of rG (r) Is considered to indicate the degree of atomic arrangement in the amorphous film. Thereafter, the degree of this order is referred to as the order degree (or
dering factor) α. here, Here, r ₁ and r ₂ are the lower and upper limits of the integration, respectively.

G (r) in the above equation (1) is Can be expressed as

Here, s is expressed as s = (4π / λ) · sin (θ / 2) (3). It is a quantity in the reciprocal lattice space (momentum space). Here, θ is the scattering angle, and λ is the wavelength of the electron beam or X-ray. In the case of reflection high-energy electron diffraction (RHEED), s is expressed as s = 2πx / λL (4). Here, x is the distance on the screen where the diffraction pattern of the sample is formed, and L is the distance between the sample and the screen.

Further, i (s) is a normalized scattering intensity, and I (S) = [I _t (s) −I _b (s)] / I _b (s) (5) Where I _t (s) is the total scattering intensity and I _b
(S) is the background intensity, which is composed of a coherent scattering component, an incoherent scattering component, and the like.

Further, in equation (2), W (s) is a window function, and β is a constant of a damping factor.

In the present invention, attention is paid to the degree of order α defined above, and the amorphous state is objectively represented by the α. The degree of order α is obtained in the same manner as the radial distribution function J (r) represented by the equation (1). That is, a sample is irradiated with an electron beam or X-ray, a diffraction pattern of the electron beam or X-ray scattered by the sample is formed on a screen of the sensor, and a correlation function rG is obtained by Fourier transform of the intensity of the diffraction pattern. By obtaining (r) and calculating the root mean square of rG (r), the degree of order α is obtained.

As described above, the order degree α which is a value representing the amorphous state in the present invention is obtained by Fourier-transforming the diffraction pattern intensity. In the present invention, the peak separation of the radial distribution function J (r), the calculation of the bond distance, the bond coordination number, and the like, which are necessary in the conventional amorphous monitoring device, are not essential in the present invention. Therefore, in the present invention, the amorphous state of the sample can be evaluated in a few seconds. As described above, if the growing amorphous film is monitored by the apparatus of the present invention that can evaluate the amorphous state in a short time, a thin film can be grown under optimum conditions, and thus an amorphous film having excellent amorphous properties can be manufactured.

(Embodiment) FIG. 1 is a configuration diagram showing one embodiment of the present invention. In this embodiment, an electron diffraction pattern of a sample is formed by a reflection high-energy electron diffraction (RHEED) method.

The RHEED electron gun 1 impinges an electron beam accelerated to about 10 to 40 kV (about 10 ⁻³す る と in terms of wavelength) on the surface of the sample 2 at a shallow angle of about several degrees. Sample 2 is an amorphous thin film such as SiO ₂ or Ni being grown on a substrate. Although this amorphous thin film is placed in a vacuum chamber, an amorphous thin film growth apparatus is not shown in this figure for simplicity. The electron beam diffracted (scattered) by the sample 2 is projected on the fluorescent screen 3 to form a diffraction pattern on the fluorescent screen 3.

The high-sensitivity TV camera 4 captures the diffraction pattern, digitizes and outputs a video signal. The frame memory 5
The digitized video signal is stored in frame units,
Only the data in the radial direction is transmitted via the interface 6
Transfer to the microcomputer 7. The microcomputer 7 calculates the degree of order α in accordance with the description in the section of (action). The degree of order α is displayed on the display of the microcomputer 7. The display 8 is a frame memory 5
And displays a diffraction pattern. The video recorder 9 also receives a video signal from the frame memory 5 and records a diffraction pattern video on a magnetic tape. The operator of the amorphous thin film growing apparatus knows the degree of order α by looking at the display of the microcomputer 7, and adjusts the growth conditions of the amorphous thin film so that the α becomes the minimum.

When data requiring a long time for calculation, such as the distance between bonds and the number of bond coordinations, is required, a host computer is connected to the microcomputer 7 and calculation is performed by the host computer.

FIG. 2 is a diagram showing the order degree α of a single-layer film obtained by monitoring the embodiment of FIG. 1 while growing an amorphous single-layer film of SiO ₂ and Ni by a dual ion beam sputter deposition method. is there. 2 (a) is an SiO ₂ film, and FIG. ₂ (b) is a Ni film.
2 shows the data for the membrane. This figure shows the dependence of the order α on the energy of argon ions assisted in the dual ion beam sputter deposition method.
From this figure, the energy of the assisted argon ion
It can be seen that a SiO ₂ thin film having the highest amorphousness can be formed by growing the film near eV. In the growth of Ni thin film,
It is preferable to assist with argon ion energy near 100 eV.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to provide an amorphous monitoring device capable of evaluating an amorphous state in a short time of several seconds. Therefore, by monitoring the amorphous state of the film with the apparatus of the present invention in the amorphous thin film growth step, a thin film having the best amorphous property can be formed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the order degree α of the single-layer film obtained by monitoring the single-layer film while growing an amorphous single-layer film, FIG. 3 is a configuration diagram showing a conventional amorphous monitoring device. 1 ... RHEED electron gun, 2,22 ... sample, 3 ... screen, 4 ... TV camera, 5 ... frame memory, 6 ...
Interface, 7,24 …… Microcomputer, 8,26
... Display unit, 9 ... Video recorder, 25 ... Host computer.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ichiro Yamada 1-21-6 Dogenzaka, Shibuya-ku, Tokyo Japan Aviation Electronics Industry Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 16/00-16/54 C30B 29/00-35/00

Claims (1)

(57) [Claims] An amorphous film is irradiated with an electron beam or X-ray, and the electron beam or X-ray scattered by the amorphous film is irradiated.
By forming a diffraction pattern of rays on a sensor and analyzing the intensity of the diffraction pattern output from the sensor, the degree of ordering of the atomic arrangement in the amorphous film is obtained. An amorphous monitoring device for outputting as data indicating a degree of crystallinity, wherein a root mean square of a correlation function obtained by Fourier transform of the diffraction pattern intensity is used as the degree of order.