JPH07225202A - Glass element concentration distribution measurement method - Google Patents

Abstract

PURPOSE:To make it possible to measure the concentration distribution of elements such as alkali metal and hydrogen in the thickness direction of glass precisely by maintaining the temperature of the glass at a low temperature when the measurement is performed by a secondary-ion mass spectrometry. CONSTITUTION:When secondary-ion mass spectrometry is performed, an electric field is formed in the thickness direction because the injecting depth of an electron beam for correcting the electric charge when primary ions such as O2<+> and Cs<+> are implanted into the surface of an insulating material such as glass is different from the implanting depth of the primary ions. It is supposed that the element such as alkali metal is moved into the deep part. And it is also supposed that thermal diffusion is generated for hydrogen by the heating of the surface of a sample by the irradiation of the electron beam. Therefore, when the elements to be measured are sodium and hydrogen, the temperature of the glass is kept at -100 deg.C or less, preferably at -150 deg.C or less, with liquid nitrogen, and the concentration distribution in the thickness direction of the glass is measured. When the concentration distribution of the sodium is measured by this method, the more accurate measurement can be performed in comparison with the case, wherein the sample is not cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the concentration distribution of glass elements, and more particularly to a method for measuring the concentration distribution of alkali metals and hydrogen in glass in the thickness direction.

[0002]

2. Description of the Related Art Measuring the concentration distribution of elements in the thickness direction of glass is essential for considering the chemical durability and electrical / optical properties of glass. X-ray microanalyzer, Rutherford backscattering, secondary ion mass spectrometry, etc. are generally used for this. In particular, secondary ion mass spectrometry has excellent positional resolution in the thickness direction and the plane direction and can detect hydrogen and trace elements, and thus has characteristics suitable for precision analysis of glass. However, when an insulator such as glass is analyzed by secondary ion mass spectrometry, it is difficult to accurately measure alkali metal elements and hydrogen due to a phenomenon induced by charging.

[0003]

The object of the present invention is to solve the above-mentioned problems of the prior art and to accurately measure the concentration distribution of alkali metals and elements such as hydrogen in the thickness direction of glass. Is to provide.

[0004]

The present invention has been made to solve the above-mentioned problems, and in measuring the concentration distribution of elements in the thickness direction of glass by secondary ion mass spectrometry, The present invention provides a method for measuring the element concentration distribution of glass, which is characterized in that the measurement is carried out while maintaining the temperature.

In the present invention, if the temperature of the glass at the time of measurement is too high, the element to be measured moves and the measurement accuracy decreases. That is, when secondary ions are analyzed by mass spectrometry, when primary ions such as O ₂ ⁺ and Cs ⁺ are incident on the surface of an insulator such as glass, the surface is positively charged. Electron beam irradiation is performed to correct this charging, but primary ions and electrons have different implantation depths, so an electric field is formed in the thickness direction. It is considered that the formation of this electric field causes the elements such as the alkali metal to move to the deep part.
On the other hand, the electron beam irradiation heats the surface of the sample, and it is considered that hydrogen causes thermal diffusion.

When the element to be measured is sodium or hydrogen, the temperature of this glass is preferably −100 ° C. or lower, particularly −150 ° C. or lower. As a method of maintaining the glass at such a low temperature, a method of circulating liquid nitrogen in a pipe directly connected to a glass support is preferable.

The element to be measured is not particularly limited, but alkali metals such as sodium, lithium and potassium, and hydrogen are preferable in that particularly accurate measurement can be performed.

[0008]

EXAMPLES Examples of the present invention will be described below.

[Example 1] 30 keV on quartz glass
Sodium was injected under the condition of 3.3 × 10 ¹⁴ cm ⁻² to prepare glass having a known concentration distribution of sodium in the thickness direction. The distribution of sodium in the thickness direction of this glass is LS
According to S theory, it is a Gaussian distribution having a peak top at a depth of 50 nm from the surface.

With respect to this glass, the concentration distribution of sodium in the thickness direction was measured by secondary ion mass spectrometry. The result is shown by the dotted line in FIG. When measuring, the glass is -15
The temperature was kept at 0 ° C. Further, the measurement conditions of the secondary ion mass spectrometry method were that a primary cesium ion beam of 4 keV was made incident at 60 degrees with respect to the normal line of the sample surface, and the positive secondary ion intensity was detected. The measurement was performed at each depth from the glass surface. The figure shows the thus-measured results, with the horizontal axis representing the depth (nm) from the glass surface and the vertical axis representing the secondary ion intensity (cps). The electron beam energy for charging correction was 1 keV.

[Comparative Example 1] The measurement was performed under the same conditions and conditions as in Example 1, except that the sample was not cooled during the measurement. The solid line in FIG. 1 shows the result.

As is clear from FIG. 1, according to the present invention, the accurate distribution of sodium in the thickness direction can be measured by the secondary ion mass spectrometry.

[Example 2] 40 keV on quartz glass
Hydrogen ions were implanted under the condition of 3.3 × 10 ¹⁴ cm ⁻² to prepare a glass sample having a known concentration distribution of hydrogen in the thickness direction. The distribution of hydrogen in the thickness direction of this sample is a Gaussian distribution having a peak top at 500 nm from the surface according to the LSS theory.

The concentration distribution of hydrogen in the thickness direction of this glass was measured by secondary ion mass spectrometry. The result is shown in Figure 2.
Is indicated by a dotted line. During the measurement, the glass was kept at the same temperature of -150 ° C as in Example 1. On the other hand, as the secondary ion mass spectrometry measurement condition, a primary cesium ion beam of 8 keV was made incident at 20 degrees with respect to the normal to the glass surface, and negative secondary ions were detected. Here, the electron beam energy for charge correction was 1 keV. When the sample was cooled and measured in FIG. 2, the accurate hydrogen concentration distribution in the thickness direction could be measured by secondary ion mass spectrometry.

[Comparative Example 2] The measurement was performed under the same conditions and conditions as in Example 2, except that the sample was not cooled during the measurement. The result is shown by the solid line in FIG. In this case, the hydrogen distribution is sloping to the deep side of the peak top, and accurate measurement cannot be performed.

As is clear from FIG. 2, according to the present invention, the accurate distribution of hydrogen concentration in the thickness direction could be measured by the secondary ion mass spectrometry.

[0017]

According to the present invention, the element concentration distribution in the glass thickness direction can be accurately measured. Further, by holding the glass at a low temperature during measurement, the measurement chamber and the like are also cooled, and the degree of vacuum in the measurement chamber is improved. As a result, the detection limit of hydrogen shifts to the low concentration side, and the effect of enabling highly sensitive analysis of hydrogen is also recognized.

[Brief description of drawings]

FIG. 1 is a graph showing the concentration distribution of sodium in the thickness direction by secondary ion mass spectrometry measured by the present invention and a conventional method.

FIG. 2 is a graph showing the concentration distribution of hydrogen in the depth direction measured by the present invention and the conventional method by secondary ion mass spectrometry.

Claims (3)

[Claims] 1. A method for measuring the element concentration distribution of glass, which comprises measuring the element concentration distribution in the thickness direction of the glass by secondary ion mass spectrometry while maintaining the glass at a low temperature. 2. The glass is made of liquid nitrogen and is -10.
A temperature of 0 ° C. or lower is maintained.
A method for measuring the element concentration distribution of the glass described. 3. The method for measuring the element concentration distribution of glass according to claim 1, wherein the elements to be measured are an alkali metal element and hydrogen.