SU1536284A1 - Method of x-ray diffractometry of thin films - Google Patents

Abstract

The invention relates to methods of X-ray quality control of materials in the form of thin films and can be used in various industries related to the production of thin films, including microelectronics. The method includes the formation of an incident beam from a line source by a system of slits, orientation of the substrate with a film at a small (mostly less than 10 °) angle to the beam axis, recording of the diffracted radiation using receiving slits and / or a monochromator and detector. In order to increase sensitivity while simultaneously improving the line to background ratio, the substrate area to be irradiated is increased by placing line source 1 in the equatorial plane of the goniometer, and the incident beam is formed by a Soller 2 collimator with plates perpendicular to the goniometer plane. 1 il.

Description

The invention relates to methods for X-ray quality control of materials in the form of thin films and can be used in various industries related to the production of thin films, including microelectronics.

The purpose of the invention is to increase the sensitivity while improving the ratio of the intensity of the diffracted radiation to the background.

The drawing shows the course of the rays in the equatorial plane P when implementing the proposed method.

A device for implementing the method comprises a radiation source 1, a Soller collimator 2 with plates perpendicular to the plane P, a slit 3 limiting the divergence of the incident beam in the direction perpendicular to Ps substrate 4 with the film under study, a flat monochromator 5, a radiation detector b. The line also shows the angle of incidence of the beam on the substrate, doubled Bragg angle 2Q of the recorded line, Bragg monochromator angle 0, Soller collimator base L, clearance between plates h, Soller’s aperture of the collimator, R (r is the distance from the slice colpimagor to goniometer axis „

In this method, the sensitivity to detecting weak diffraction pines from thin films is increased due to an increase in the irradiated area of the substrate S0 and an increase in the intensity of diffraction lines while simultaneously improving the signal-to-background ratio. The increase in S 0 is increased by increasing the width of the incident beam in the P plane while maintaining the dimensions of the latter in the direction perpendicular to P. When a incident beam is formed by the Soller collimator, when the plates are perpendicular to P, the width of the beam b is determined once a measure of the line source f placed in the plane P and the beam divergence defined by the aperture of the Soller collimator according to the expression

((Rj + L / 2). (O

Since the aperture of the Soller collimator is determined by its design parameters — base I, and the distance between the plates h), then the typical conditions of the experiment

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the value of the second term in (1) does not: exceed (0.3-0.5) f and the beam width b is determined mainly by the first term. Thus, a decrease in o has little effect on S0 and, with improved collimation, leading to an increase in the peak intensity of the lines while maintaining the background level, the intensity of which for known sources is determined by the irradiated area S0, an improvement in the ratio of the intensities of the lines to the background is achieved.

Example. The method is implemented under the following conditions. A tube 2, OBB-24 with a line focus of 10 0.2 mm, is used as the radiation source, the casing of which is set so that the maximum projection of the mm focus lies in the equatorial (horizontal) plane of the goniometer. Anode material - chrome, tube mode 40 kV, 50 mA. The incident beam is formed using a Soller 2 collimator with vertical plates mounted on a standard liner. The design parameters of the collimator 2 are as follows: base mm, divergence angle from (10, clearance between plates 0.32 mm, transmittance 76%, Vertical divergence of the beam is limited by a slit 3 with a height of 8 mm A silicon wafer with a diameter of 76 mm cut along a plane with a deposited gold film 0.1 μm thick is taken as the substrate 4. The substrate is oriented on a BG-0 goniometer at an angle U) 8.8 to the beam axis. Diffracted radiation is recorded using a flat graphite monochromator 5 on reflection (00.2) with interplanar spacing, 354 A and a BTsS-6 detector. The measured pitch intensity 220 with a diffraction angle, 7 is 1 ,,, 0 700 pulses / s with a peak exceeding the line above the background by 2.5 times. Corresponding measurements by the prototype method with equal tube modes, angle of incidence and horizontal beam divergence give a value of 188 pulses / s. The signal-to-peak ratio for the prototype method at a background level of 85 pulses / s is 2.2. The irradiated area of the substrate increases in comparison with the prototype by 4.9 shrimps from 2.5 to 12.1 cm2.

Thus, the proposed method provides an increase in sensitivity, determined by the ratio of line intensities (220), not less than 3.7 times while simultaneously improving the signal-to-background ratio. The advantage of the proposed method is also an increase in the reliability of the results obtained by X-ray phase analysis, by increasing the irradiated area of the substrate.

Claims (1)

Invention Formula X-ray diffractometry of thin films, including the formation of an incident beam from a line source by a system of slits containing a Soller collimator, orientation of a substrate with a film at a small angle to the beam axis in the equatorial plane, formation of diffracted radiation using receiving slits and / or a plane monochromatic registration and detection of the detector by the fact that, in order to increase the sensitivity while improving the ratio of the intensity of the diffracted radiation to f Well, have a line source in the equatorial plane of the goniometer and Soller collimator is positioned so that its plate perpendicular to the equatorial plane of the goniometer. Compiled by O. Aleshko-Ozhevsky Editor I. Casarda Tehred M. Khodanych Proofreader V. Kabatsy Order 104 Circulation 488 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and publishing plant Patent, Uzhgorod, st. Hagarn m, I ll Subscription