JPS62113052A - Element analysis - Google Patents

Abstract

PURPOSE:To reduce the beam diameter while making the penetration depth into sample shallow, by employing ion seed with large ion radius exceeding 35 in the mass number for primary beam to be an ion beam. CONSTITUTION:An ion seed such as Xe introduced into an ionization chamber 4 is accelerated to 5-15keV in the ionization chamber 4 and is made to irradiate onto a sample 1 comprising an insulation film as a primary beam (ion beam) 2 through an electronic optical system lens section 5. A specific X rays 3 generated from a surface layer area of the sample 1 are diffracted with a spectroscope 6 and is projected onto an X rays detector 7. Generally speaking, the penetration depth of the primary beam 2 needs to be controlled below 50Angstrom to analyze element distribution in the direction of surface and depth. Thus, irradiation ion seed is preferable large in the ion radius exceeding 35 in the mass number.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an elemental analysis method, and particularly to the measurement of elemental distribution in the surface and depth direction of a minute region of an insulating film.

[Conventional technology]

In recent semiconductor process technology, high-sensitivity analysis methods such as activation analysis and quality 1 analysis have been used to evaluate not only the impurity concentration in p-no-9 but also process evaluation and 1 to 1, especially in minute areas of component materials being processed. Techniques for analyzing elements both on the surface as well as in the depth direction are increasingly required.

A conventional general elemental analysis method will be explained based on FIG. The sample 1 is
When the primary beam 2 is irradiated to the area, a secondary beam 3 is generated accordingly. Then, this secondary beam 3 is separated by a spectroscope 4 and made incident on a secondary beam detector 5 to perform elemental analysis. In this case, ions, electrons, and X-rays are used as the primary beam 2 and secondary beam 3.

The relationship between the primary beam 2 and the secondary beam 3 in each Yuzu analyzer is shown in the table below.

[Grudge] AES: Auger electro
n5pectroscopyS IMS: 5ec
ondary ton mass 5pectrosc
oByXPS: X-, ray photo el
ectron spectroscopy EPMA:
Electron probe m1croanal
ysisPIXE: Particle 1nd
uced X-ray Fm1ssionHere, the analysis area of sample 1 depends on the primary beam 2, and when X-rays are used (), only a radius of 1 to 10 mm can be analyzed, but with ion beam or electron beam Then, by narrowing down the beam, 1
Analysis of minute regions of 0 μmφ or less becomes possible. In addition, the analysis depth depends on the secondary beam 3, and in the case of an electron beam, it is possible to target the vicinity of the surface of about 5 to 30 A, which corresponds to the so-called escape depth, but in the case of an X-ray or ion beam, the primary beam It is also related to the penetration depth of 2.

Next, in the case of an insulating film, the electric charges (electrons or i
We will discuss the accumulation of hole E). There are two types of charge accumulation: the primary beam 1/2 and the secondary beam 3, but generally the primary beam 2 has a large influence. That is, if the primary beam 2 is made up of ions or electrons, which are charged bodies, charges tend to accumulate, and therefore, if the secondary beam 3 is also a charged body, the energy will change, making it impossible to perform spectroscopy. .

For the above reasons, current analytical methods such as AES and SI
In MS, since both the primary beam 2 and the secondary beam 3 are charged bodies, insulating films cannot be analyzed, so XPS, E uses X-rays for either the primary beam 2 or the secondary beam 3.
Elemental analysis of insulating films can be performed using PMA and PIXE. Among these, PIXB has the characteristics of high X-ray analysis sensitivity and low output limit protection (1)I)m order), and has a wide range of applications including insulators (Japan Society for the Promotion of Science 141 Committee 42nd Study Group Materials Na45
5 (59, 12, 4-5)).

[Problem that the invention seeks to solve]

However, in the EPMA described above, the secondary beam 3 is an X-ray, and the generation region thereof reaches several micrometers from the surface, so it is not suitable for surface analysis, and analysis in the depth direction is also difficult. Furthermore, in the above-mentioned XPS, since the primary beam 2 is an X-ray, it is difficult to analyze a minute area.

Furthermore, the above P I XE has protons in the primary beam 2,
Since ions with a small ionic radius such as He ions are used, the analysis depth is as large as about several μm, which is not suitable for surface and deep analysis.

Therefore, an object of the present invention is to provide an elemental analysis method that solves the above-mentioned problem of difficulty in elemental analysis in the surface and depth directions of minute regions of an insulating film.

[Means for solving problems]

The elemental analysis method according to the present invention includes the following steps: (a) using an ion beam using an ion species with a particle number of 35 or more as the primary beam, and irradiating the sample with this ion beam through an electron optical system lens part; ) The characteristic X-rays generated by the ion beam irradiation are incident on an X-ray detector via a spectrometer and analyzed.

[For production]

As described above, since the present invention uses an ion beam as the primary beam, the beam can be narrowed down sufficiently by the electron optical system lens section. Furthermore, since the ion beam uses ion species with a quality-1 number of 35 or more and has a large ion radius, its penetration depth is limited to the vicinity of the surface of the sample.

Furthermore, since characteristic X-rays are generated as a secondary beam, the sample is completely destroyed! In the case of membranes, charge accumulation can be reduced.

Furthermore, sputter etching can also be performed on the sample by irradiating the ion beam.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIG. First, the ion species such as Xs introduced into the ionization chamber 4 are accelerated to about 5 to 15 KeV in the ionization chamber 4, and the well-known electron optical system lens section consisting of a scanning lens, a condenser lens, an objective lens, etc. The sample 1 made of an insulating film is irradiated as a primary beam (ion beam) 2 through the ion beam 5, and the ion beam 2 is focused to a diameter of about 1 to 10 μm in the electron optical system lens section 5. , an arbitrary amount of light is irradiated onto an arbitrary part of the sample 1.

Further, the penetration depth of the ion beam 2 irradiated onto the sample 1 is ~50'A or less depending on conditions such as accelerating voltage and ion species, and characteristic X-rays are generated as the secondary beam 3 from this surface layer region. And then it happened.

The characteristic X-ray 3 is diffracted by a spectrometer 6 made of a spectroscopic crystal, and
The beam is incident on the ray detector 7. In this case, the spectroscopic crystal 6 and
The ray detector 7 can be rotated together, and characteristic X-ray 3 digits λ=2dsi
It is possible to have a peak where nθ is satisfied. During the ceremony,
λ is the wavelength of the characteristic X-ray 3, d is the interplanar spacing of the spectroscopic crystal 6, and θ is the incident angle of the characteristic X-ray 3 with respect to the spectroscopic crystal 6.

The characteristic X-ray 30 spectroscopy and detection method is based on the same principle as the EPMA and fluorescence X-ray analyzers, and other live conductor detectors can also be used.

In the present invention, since the ion beam 2 is used as the primary beam, the beam diameter can be narrowed down to approximately 1 to IO μmφ, while the penetration depth of the ions can be adjusted from the surface to It can be limited to a range of 50A. Therefore, as described above, since it is possible to generate the characteristic X#3 as a secondary beam from the surface layer region of the sample 10, it is suitable for surface analysis of a minute area. - Since the secondary beam is still the characteristic X-ray 3, it has the advantage of little charge accumulation, and insulating films can be analyzed.

Furthermore, by selecting the accelerating voltage and ion species, the surface of the sample 1 can be sputter-etched, so elemental analysis in the depth direction can also be performed.

For example, when targeting Si, the ion species is Sl(
Xe (131) has a larger mass number than 28).

By using C5 (133) or the like and setting the accelerating voltage to about 15 KeV, the 981 surface can be easily sputter-etched.

In addition, in the case of an insulating film such as SiOx + Sis N4, Snow? You can apply ivy etch.

Generally, in order to analyze the elemental distribution on the surface or in the depth direction, it is necessary to suppress the penetration depth of the primary beam 2 to 5()A or less. bilchi, 100 A tH! If the ions penetrate to a deep position t, it becomes difficult to specify the position of the emitted characteristic X-ray 3. Therefore, as the ion species for irradiation,
Those having a mass number of 35 or more and a large ionic radius are preferable, and Kr (84), Xe, and Cs are preferable as single gases. The lower the accelerating voltage, the shallower the penetration depth.
At a voltage as low as 5 KeV, only the following elements among the elements in the sample can be excited. Therefore, at least 5 KeV is required to analyze all elements, and 15 KeV is usually preferred.

〔Effect of the invention〕

As explained in detail above, according to the present invention, since the primary beam is an ion beam using an ion species with a mass number of 35 or more and a large ion radius, the beam diameter can be made sufficiently small and the penetration depth into the sample can be reduced. The surface is shallow, and the surface can be sputter-etched. Furthermore, since characteristic X-rays are generated as a secondary beam, accumulation of charge on the sample is suppressed.

Therefore, it is particularly effective in being able to measure the elemental distribution in the surface and depth directions of minute regions of the insulating film, and has high industrial utility value.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention, and FIG. 2 is a schematic diagram illustrating a conventional example. 1... Sample (insulating film), 2... Primary beam (ion beam), 3... Secondary beam (% X-ray), 5...
Electron optical system lens section, 6... Spectrometer (spectroscopic crystal), 7
...X-ray detector. Patent applicant Oki Electric Industry Co., Ltd.

Claims (2)

[Claims] (1) In an elemental analysis method in which a sample is irradiated with a primary beam and the energy characteristics of the generated secondary beam are analyzed, (a) the primary beam is an ion beam using an ion species with a mass number of 35 or more; irradiating the sample with the ion beam via the electron optical system lens; (b) making the characteristic X-rays generated as a secondary beam by the ion beam irradiation enter the X-ray detector via the spectrometer; An elemental analysis method characterized by comprising the step of analyzing. (2) The elemental analysis method according to claim (1), wherein the ion beam is irradiated to sputter-etch the surface of the sample.