JP3030311B2 - Simple measurement method of boron concentration of boron-added diamond - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for measuring the boron concentration of boron-added diamond, which can easily measure the concentration of boron added as an impurity to diamond without contacting the sample without any damage. It relates to a simple measurement method.

[0002]

2. Description of the Related Art Boron is known as an impurity which forms the shallowest acceptor level in diamond, and is an essential impurity for forming a p-type semiconductor when manufacturing a diamond semiconductor device. As a method of knowing the concentration of boron impurities in such a case, for example, (a) secondary ion mass spectrometry, (b) Fourier transform infrared spectroscopy, and the like are conventionally known.

(A) Secondary ion mass spectrometry (SIMS)
The method for evaluating the boron concentration using is described in, for example, Volume 7 of Diamond and Related Materials as a document,
1998, p. 88-p. As disclosed in US Pat. No. 95, specifically, a method in which a sample is analyzed by accelerated irradiation of oxygen ions or the like to a sample to grind the surface of the sample using a mass spectrometer.

On the other hand, (b) Fourier transform infrared spectroscopy
For example, as a document, Journal of Physics
(Journal of Physics), Vol. 4, 1971, p. 178
9 · p. As disclosed in 1800, specifically, this is a method of estimating the boron concentration of a sample from an absorption peak intensity of 0.348 eV in an infrared absorption spectrum obtained by a Fourier transform infrared spectrometer.

[0005]

However, among the conventional methods described above, (a) secondary ion mass spectrometry is essentially a destructive measurement method, and it is necessary to measure impurities without damaging the sample. And there is a limit in the re-evaluation and reusability of the sample. In addition, there is a disadvantage that a large-scale apparatus that requires a high vacuum system is required, and the maintenance and management of the apparatus, including the replacement of the sample, requires a lot of trouble. In addition, (b) Fourier transform infrared spectroscopy is non-destructive,
Although it is a non-contact and simple evaluation method, measurement is often impossible when a large amount of boron is doped. Further, since the spatial resolution is at most about 50 μm ² and the measurement is performed in the transmission configuration, for example, diamond single-crystal particles (diameter of about 5 μm
Measuring the spectrum of degree is almost impossible because of the lack of spatial resolution and the unavoidable influence of the substrate. Therefore, the invention of this application solves the above-mentioned drawbacks of the prior art, and can measure easily without contacting the sample without any damage, and has a spatial resolution excellent in the order of visible wavelength. It is an object of the present invention to provide a new simple method for measuring the boron concentration of boron-added diamond by optical measurement.

[0006]

In order to solve the above problems BRIEF SUMMARY OF THE INVENTION Since the Raman scattering spectrum band generated 1400 cm ^-1 from the Raman shift energy 500 cm ^-1, which is correlated to the boron concentration by boron impurity contamination,
The invention of this application utilizes this property to estimate the boron concentration in the diamond sample from the determination of the shape approximation by comparing the Raman scattering spectrum shape with the spectrum shape of the sample of known concentration.

According to the method of the present invention, the boron concentration of the sample can be measured by observing the Raman scattered light signal generated by the relatively weak incident light intensity, for example, about 1 mW, so that the sample is not damaged at all. When a light source such as an argon ion laser (514.5 nm) is used as the incident light, the light source can be narrowed down to about 1 μm in diameter, so that a spatial resolution of 1 μm can be easily obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the features as described above. Examples will be shown below, and embodiments of the invention will be described.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The drawings used in the description are exemplifications, and merely schematically show the dimensions, shapes, and arrangements of the components so that the present invention can be understood. Therefore, the present invention is not limited to the following description.

FIG. 1 shows an example of the configuration of a measuring apparatus for the method of the present invention. For example, as an incident light source, an argon ion laser (wavelength 514.5 nm)
(1) is used. The sample (3) is irradiated with the incident light laser beam by the condenser lens (2). The scattered light from the sample (3) is collected again by the condenser lens system (2), enters the spectroscope (4), and is processed by the computer (6) detected by the photodetector (5). . At this time, a spatial resolution of about 1 μm can be obtained by using a confocal optical system using a microscope lens or the like for the condenser lens system (2).

The configuration of the measuring device is not limited to FIG. 1 but can be variously modified. FIG. 2 shows an example of Raman scattering spectra of several samples having different boron concentrations measured using the measuring apparatus having the configuration of FIG. 1 described above. The boron concentrations indicated by letters and numbers in the figure are values calibrated carefully by secondary ion mass spectrometry. 500 cm ^-1 to 1400 cm as a function of boron concentration as boron concentration increases
^-1 , more specifically, the shape of the Raman scattering spectrum distributed in the vicinity of 500 cm ^-1 to 1200 cm ^-1 changes.
By using FIG. 2, for example, the boron concentration of an unknown sample showing the Raman scattering spectrum shown in FIG. 3 can be estimated. That is, in the case of the sample illustrated in FIG. 3, since the shape of the spectrum at 500 to 1200 cm ^-1 is similar to that of FIG. 2A, the concentration is 7 × 10 ¹⁸ cm ^-1 .
^It can be estimated to be about ^-3 .

The determination of the similarity of the spectral shapes, that is, the shape approximation, may be made by visual inspection, or, for example, by an automatic determination system using the computer (6) of the apparatus shown in FIG. Becomes

[0013]

As is clear from the above description, according to the invention of this application, the amount of boron impurities in a diamond sample as a semiconductor material is measured in a non-destructive non-contact and spatial resolution of about 1 μm ³ in every scene. Can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a measuring device as an embodiment of the present invention.

FIG. 2 is a diagram illustrating the relationship between the concentration of boron in diamond and Raman scattering as an example of the present invention. The numbers in the figure indicate the boron concentration of each sample.

FIG. 3 is a diagram showing an example of a Raman scattering spectrum of a diamond sample whose boron concentration is unknown as an example of the present invention.

[Description of Signs] 1 Argon ion laser 2 Condensing lens system 3 Sample concerned 4 Spectrometer 5 Photodetector 6 Computer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Ando 1-1-1, Namiki, Tsukuba, Ibaraki Prefectural Science and Technology Agency Inorganic Materials Research Laboratory (72) Inventor Hisao Kanda 1-1-1, Namiki, Tsukuba, Ibaraki Pref. Inorganic Materials Research Laboratories of the Agency of Japan (72) Inventor Yoichiro Sato 1-1-1, Namiki, Tsukuba, Ibaraki Prefecture Inorganic Materials Research Laboratory of the National Science and Technology Agency (72) Inside the Materials Research Laboratory (72) Inventor Mika Gamo 1-1, Namiki, Tsukuba, Ibaraki Pref. Inorganic Materials Research Laboratory, Science and Technology Agency (56) References JP-A-1-2844741 (JP, A) JP-A-8-330624 ( JP, A) JP-A-10-38807 (JP, A) JP-A-4-127039 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/62-21/74 G01J 3/44 ICST file (JOIS)

Claims (1)

(57) [Claims] 1. A method for easily measuring the boron concentration of diamond to which boron is added as an impurity, wherein the Raman shift energy is 500 c
It is characterized by measuring the boron concentration in a non-contact manner without damaging the sample by judging the shape approximation of the spectral shape of the Raman scattering spectrum band generated from m ^-1 to 1400 cm ^-1 with the spectrum shape of the known sample. Simple measurement method of boron concentration of boron-added diamond.