JPS59116515A - Method for measuring polarized light transmitting infrared absorbing spectrum - Google Patents

Abstract

PURPOSE:To make it possible to measure the spectrum of a thin film, which is formed on a substrate in a clear state where an interference spectrum is not superimposed, by projecting the light of a vertical vibrating component with respect to the incident surface of a sample, so that the incident angle becomes a Brester angle at the boundary between the thin film and the substrate with respect to the sample. CONSTITUTION:On a fixed plate 1, a guide 2 and a rotary sample table 3 are arranged. In the outside surface of the guie 2, a groove 2a, which is coupled with a slider in a sample chamber of an infrared spectrophotometer, is formed. At the center of the guide 2, a through hole 2b is formed. A polarizer 4, which transmits only the light of a vertical vibrating component with respect to the incident surface of a sample among infrared rays, is arranged at one end. Meanwhile, the rotary sample table 3 comprises a base 5, which is fixed to the fixing plate 1; a rotary table 6, which is rotatably supported by the base 5; and plate springs, which are arranged at the stepped part formed on the rotary table 6. A sample 8 is fixed to the stepped part of the rotary table 6 by the plate springs 7.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for measuring polarized light transmission infrared absorption spectra suitable for obtaining the original infrared absorption spectrum of a sample without superimposition of interference spectra caused by the thickness of the sample that appears when measuring external absorption spectra. When measuring molarity, interference spectra caused by the thickness of the sample may be superimposed and the original spectrum of the sample may not be obtained. Conventionally, such samples were KH2-
A total reflection absorption spectrum measuring device was used that measures the total reflection component of infrared light by placing the sample in close contact with a prism of No. 5 or the like. However, if the silicon wafer is not flat, it will not come into close contact with the prism, making it difficult to measure its infrared absorption spectrum. Furthermore, the prism used was a toxic substance and had to be handled with care.

For example, if you measure the infrared absorption spectrum of a 5 μm silicon nitride film formed on a silicon wafer using a normal infrared spectrophotometer using the transmission method, you will obtain the spectrum shown in Figure 1. .

In the spectrum shown in FIG. 1, the large webbing is due to the silicon nitride film, and the small webbing superimposed on this webbing is due to the thickness of the silicon wafer. In this way, in the interference spectrum where two waves are superimposed, the sample [Category 1 Hari+Water L"D'E] When measuring a thin film, the infrared light has a vertical vibration component with respect to the plane of incidence on the sample. It will be explained that the original infrared absorption spectrum of the sample can be obtained by irradiating the sample with light and removing various reflected lights that cause interference spectra.

Figures 2 to 4 show an embodiment of the present invention,
In the figure, a fixed plate 1 includes a guide 2 and a rotating sample stage 3.
is located. The outer surface of the guide 2 has a groove 2 that fits into a slider (not shown) in the sample chamber of the infrared spectrophotometer.
a is formed. A through hole 2b is formed in the center of the guide 2, and a polarizer 4 is disposed at one end of the through hole 2b, which transmits only the vertical vibration component of the infrared light with respect to the incident surface of the sample. On the other hand, the rotating sample stage 3 includes a base 5 fixed to the fixed plate 1, a rotating table 6 rotatably supported by the base 5, and a plate spring disposed on a step formed on the rotating table 6. It consists of 7. The sample 8 is fixed to the stepped portion of the rotary table 6 by a leaf spring 7.

In the above configuration, for example, by sputtering,
A silicon wafer on which a 5 μm silicon nitride film was formed was used as sample 8. This sample was placed on a rotating table 6 and fixed with a leaf spring 7, and then the rotating table 6 was rotated so that the incident angle of infrared rays on the sample 8 was 63 degrees. Set it so that

In this state, infrared rays are irradiated and measurement is performed using a transmission method. At this time, the infrared rays irradiated onto the sample pass through the polarizer 4 and become only light with a vibration component perpendicular to the plane of incidence on the sample.

As a result of measurement in this manner, as shown in FIG. 4, it was possible to obtain the original spectrum of the sample without any interference spectrum.

In the above embodiment, by arranging the polarizer 4 at the position where the infrared light of the infrared spectrophotometer is focused on the sample, the expensive polarizer can be made smaller and the vibration component perpendicular to the incident plane can be reduced. The spectrum of the thin film formed on the substrate can be determined by irradiating the sample with light at an angle of incidence equal to the Prister angle at the boundary between the thin film and the substrate and measuring the transmitted infrared absorption spectrum. This has the advantage that measurements can be made in a clear state without interference spectra overlapping.

[Brief explanation of the drawing]

Fig. 1 is a spectrum diagram showing measurement results by a conventional transmission infrared absorption spectrum measurement method, Fig. 2 is a front view showing an example of the measuring instrument used in the present invention, and Fig. 3 is a plan view of Fig. 2. 4 are spectral diagrams showing the results of measurement using the method of measuring polarized light transmission infrared absorption spectra according to the present invention. 3... Rotating sample stage 4... Polarizer 8... Patent attorney representing the sample Susuki 1) Toshiyuki Wha VkNLiffll north) (C order - Li 1 + f
'1 display Showa 57! 11 Patent Application No. 226036 Cissy Title of Invention Method for Measuring Polarized Light Transmission Infrared Absorption Spectrum
Works! ',' 21 (1-(III II Inn Shigeyo Osamu 1,・j Location 〒1(3) Marunouchi, Chiyoda-ku, Tokyo-
Chome 5-1 Hitachi Ltd. Xl・ Story ・”・
1. 435-4221 Sleeve iJE Contents As per the separate notice, the number of weeks (0 works - 1)

Claims (1)

[Claims] A thin film formed on a substrate that does not absorb infrared light is used as a sample, and the infrared light has a vertical vibration component with respect to the plane of incidence on the sample. A method for measuring polarized light transmission infrared absorption spectra, which is characterized by irradiating with a blister angle of .