JPH0547334A - Two-dimensional electron spectroscopic device - Google Patents

Abstract

PURPOSE:To concurrently make spectral diffraction on electrons emitted from various positions of a sample and two-dimensionally analyze the sample in a short time. CONSTITUTION:A grid 17 made of a conductor with openings corresponding to photo-diodes 14 is provided on the front face of a diode array 15 constituted of two-dimensionally aligned fine photo-diodes 14, and the blocking voltage Vb applied to the grid 17 is scanned to detect the energy distribution. An electron lens 50 diffusing photoelectrons is provided between a sample and the grid 17 to improve the positional resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectron spectroscope for analyzing a sample by irradiating the sample with X-rays and the like and measuring the energy distribution of photoelectrons emitted from the sample.

[0002]

2. Description of the Related Art As an apparatus (photoelectron spectroscopic apparatus) for measuring the energy distribution of photoelectrons emitted from a sample, there are a blocking electric field type photoelectron spectroscopic apparatus and an electrostatic hemisphere type photoelectron spectroscopic apparatus. In the blocking electric field type photoelectron spectrometer, an electric field that prevents the photoelectrons from entering the electron detection unit is formed, and the magnitude of the electric field is continuously changed (scanned) to obtain the energy distribution of the photoelectrons. To measure. In the electrostatic hemispherical photoelectron spectrometer, photoelectrons are passed through an electrostatic field formed in a hemispherical electrode to separate the orbits for each energy of electrons and measure the number of electrons.

[0003]

In any of the above types of photoelectron spectroscopic devices, the photoelectrons emitted from the surface of the sample to be analyzed are all collected and counted regardless of the emission position, so the position of the sample It was not possible to obtain analysis information for each. When it is inevitable to obtain position information, the position where the photoelectrons are sampled is narrowed down and the sample (or photoelectron spectroscopic device) is moved (scanning the sample surface) to perform spectroscopic analysis for each position. Such a method has a problem that it takes a long time to analyze one surface.

The present invention has been made to solve such a problem, and an object thereof is to simultaneously disperse electrons emitted from respective positions of a sample and perform a two-dimensional analysis (area analysis). It is intended to provide a two-dimensional electron spectroscopic device capable of performing (2) in a short time.

[0005]

A two-dimensional electron spectroscopic apparatus according to the first invention made to solve the above problems is
(A) an electron detection section composed of minute electron detection elements arranged two-dimensionally, and (b) a grid of conductors covering the front surface of the electron detection section and having openings corresponding to the respective electron detection elements. And a configured blocking electrode.

Further, in the two-dimensional electron spectroscopic device according to the second aspect of the present invention, (c) electrons emitted from the sample are provided between the sample and the blocking electrode that two-dimensionally emit electrons from the surface. And an electron lens for diffusing the bundle in a plane parallel to the grid.

[0007]

In the two-dimensional electron spectroscopic device of the first aspect of the invention, electrons (usually photoelectrons emitted by irradiation of electromagnetic waves such as X-rays, but electrons emitted by irradiation of particle beams such as electrons may be used). It is placed so as to face the front surface of the sample to be emitted (that is, the grid is located between the sample and the electron detector). Then, a positive voltage is applied to the grid and the voltage is continuously changed. Thereby, the energy distribution of the electrons emitted from the sample can be measured for each electron detection element of the electron detection unit, as in the case of the blocking electric field type photoelectron spectrometer. That is, surface analysis can be performed.

In the two-dimensional electron spectroscopic device of the second invention, the electrons emitted from the sample are diffused in the plane parallel to the grid surface, so that the positional resolution of analysis is improved. For example, if the electron lens spreads the electron bundle twice in the lateral direction, the positional resolution of the analysis is doubled.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a two-dimensional electron spectroscopic apparatus which is an embodiment of the first invention is shown in FIGS. As shown in FIG. 1A, the two-dimensional electron spectroscopic device 10 of the present embodiment includes a grid unit 1.
1 and the electron detector 12. The electronic detection unit 12 is
Photodiodes 14 that are minute electron detection elements are vertically and horizontally arranged on a semiconductor substrate 13 (a two-dimensional array of the photodiodes 14 is referred to as a diode array 15). As the electron detecting element, an avalanche photodiode made of a semiconductor superlattice, an ordinary photodiode having a scintillator crystal vapor-deposited or epitaxially grown on its surface, and the like can be used.

The grid section 11 is fixed to the front surface of the electron detection section 12 (the surface on which the photodiode 14 is formed) with a small distance from the electron detection section 12. In the embodiment of FIG. 1, the spacer 16 for fixing the distance between the two is also included in the grid portion 11, and is integrally formed when the grid portion 11 is formed as described later. In the portion of the grid portion 11 facing the diode array 15,
Grid 17 having an opening for each photodiode 14
Are formed (FIG. 1B). A conductor layer 18 is provided on the surface of the grid 17.

An example of a method of manufacturing the two-dimensional electron spectroscopic device 10 will be described with reference to FIG. (I) Polish both sides of the silicon wafer 30. (Ii) Form oxide films 31 and 32 on both surfaces of the wafer 30. (Iii) The oxide film 32 on one surface (lower surface in FIG. 3) is removed by etching, leaving the peripheral portion of the wafer 30. (Iv) Using the remaining oxide film 32 as a mask, APW (etching solution) is used to dig into and etch the central silicon wafer 30. The wafer 30 in the peripheral portion left by this becomes the spacer 16. (V) By the same etching as in (iii), the oxide film 31 on the other surface (the upper surface in FIG. 3) is formed in a grid pattern (see FIG. 1).
The openings are removed, leaving (b)). (Vi) A grid-shaped hole is opened in the remaining silicon wafer 30 by using the grid-shaped oxide film 31 as a mask by wet etching or dry etching of KOH. (Vii) Conductor layer 1 is formed on the surface of oxide film 31 by vapor deposition of gold or the like.
8 is formed. Further, the oxide film 32 on the opposite side is removed.
As a result, the grid portion 11 is formed. (Viii) (not shown) above (v) on the silicon substrate 13
A two-dimensional array (diode array 15) of the photodiodes 14 is formed at the same pitch as the grid 17 formed in (but slightly larger than the opening of the grid 17) to form the electron detection unit 12. (Ix) The electron detection unit 12 and the grid unit 11 are bonded to each other, and 2
The three-dimensional electron spectroscopic device 10 is completed (FIG. 1A). Since both the substrate surface of the electron detection unit 12 and the surface of the spacer 16 of the grid unit 11 (lower surface in FIG. 3) are optical planes, they can be bonded by optical contact.

In FIG. 1 and FIG. 3, the number of openings of the grid 17 is 4 × 4 for convenience of understanding, but in reality, a grid having a much larger number of minute openings is formed. , It is possible to improve the resolution regarding the position of the surface analysis.

The positional relationship between the photodiode 14 and the grid 17 is enlarged and shown in FIG. The openings of the grid 17 correspond to the photodiodes 14 of the diode array 15 of the electron detector 12, and the electrons incident from the openings enter only the corresponding photodiodes 14.

When the present two-dimensional electron spectroscope 10 is used, it is arranged so that the grid 17 side faces the surface of the sample 20, as shown in FIG. Then, as shown in FIG. 2, a variable DC voltage (blocking voltage) Vb is applied between the grid 17 and the substrate 13 of the electron detector so that the grid 17 side is positive.

When the sample 20 is irradiated with X-rays 21 or the like, photoelectrons 22 are emitted from each position on the surface of the sample 20. The photoelectrons 22 emitted from the respective positions of the sample 20 are directed to the two-dimensional electron spectroscopic device 10, but the blocking energy (blocking voltage) Vb determined by the potential difference (blocking voltage) Vb is generated by the electric field formed between the grid 17 and the substrate 13. = E · Vb), electrons having a weaker energy than eVb are prevented from reaching the substrate 13, and only the electrons having the energy higher than the blocking energy are detected by the photodiode 14. Therefore, the energy distribution of the electrons emitted from the sample can be measured by continuously changing the blocking voltage Vb. Further, by bringing the two-dimensional electron spectroscopic device 10 sufficiently close to the sample 20, the electrons emitted from a certain position of the sample 20 (passing through the grid 17) enter only the photodiode 14 facing the position. Therefore, the analysis of each position of the sample can be performed at one time.

The two-dimensional electron spectroscopic device 10 of this embodiment
Specifically, the thickness dm of the grid 17 is about 100 μm, and the distance dt between the grid 17 and the photodiode 14 is about 1 mm. Since the energy of photoelectrons generated by X-ray irradiation is usually about 1 keV, the blocking voltage Vb is about 1 when dt = 1 mm.
It will scan around kV. Also, grid 1
The size of 7 is appropriately changed according to the required position resolution. For example, the size dw of the eye (opening) is 5
About 0 μm, the size of the crosspiece (shield) ds is also 50 μm
It can be about m.

The second is the one that has improved the positional resolution of this analysis.
It is an invention, and one embodiment thereof is shown in FIG. In this embodiment, an electron lens 50 is provided between the sample 20 and the two-dimensional electron spectroscope 10 shown in FIG. 4, and the bundle of electrons 22 emitted from the sample 20 is reflected on the surface of the grid 17 of the two-dimensional electron spectroscope 10. Is diffused in a direction parallel to. In order to diffuse the bundle of electrons 22, the electron lens 50 is composed of a ground electrode 51 having a small diameter hole provided on the sample 20 side and a diffusion electrode 52 having a large diameter hole provided on the spectroscopic device 10 side. To do. The holes of both electrodes 51, 52 are concentric circles, and a positive DC voltage is applied to diffusion electrode 52. Thereby, both electrodes 51, 52
An electrostatic field that uniformly expands from the sample 20 side toward the spectroscopic device 10 side is formed in the hole portion, and the electron bundle passing therethrough is diffused in the lateral direction (horizontal direction in FIG. 5). Therefore, the electrons emitted from the relatively narrow range of the sample 20 are expanded to a wide range by the electron lens 50, and the positional resolution of the analysis in the two-dimensional electron spectroscope 10 is improved.

Although the analysis range is narrowed because the electron lens 50 is used in this embodiment, when two-dimensional analysis of a wide range of the sample 20 is required, as shown by the arrow in FIG. The method of moving the sample 20 (or moving the analysis system including the electron lens 50 and the spectroscopic device 10) can be used together.

[0019]

In the electron spectroscope according to the present invention, the electrons emitted from each position on the surface of the sample can be detected two-dimensionally at once and the energy distribution thereof can be measured, so that the surface analysis of the sample is short. Can be done in time. Further, by providing an electron lens between the two-dimensional electron spectroscopic device and the sample, it is possible to enhance the resolution regarding the position of analysis and obtain more detailed surface analysis information.

[Brief description of drawings]

FIG. 1 is a sectional view (a) and a plan view (b) of a two-dimensional electron spectroscopic device that is an embodiment of the first invention.

FIG. 2 is an enlarged cross-sectional view of the two-dimensional electron spectroscopic device of the same example.

FIG. 3 is an explanatory view showing a manufacturing process of the two-dimensional electron spectroscopy apparatus of the embodiment.

FIG. 4 is a layout diagram at the time of surface analysis by the two-dimensional electron spectroscopic apparatus of the same embodiment.

FIG. 5 is a sectional layout view of a two-dimensional electron spectroscopic apparatus with an electron lens that is an embodiment of the second invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Two-dimensional electron spectroscope 11 ... Grid part 12 ... Electron detection part 13 ... Substrate 14 ... Photodiode 15 ... Diode array 16 ... Spacer 17 ... Grid 18 ... Conductor layer 20 ... Sample 50 ... Electron lens 51 ... Ground electrode 52 ... Diffusion electrode Vb ... blocking voltage

Claims (2)

[Claims] 1. An electron detecting section comprising (a) two-dimensionally arranged minute electron detecting elements, and (b) a front surface of the electron detecting section is covered with an opening corresponding to each electron detecting element. A two-dimensional electron spectroscopic apparatus comprising: a blocking electrode configured by a grid of conductors having. 2. (a) An electron detecting section composed of minute electron detecting elements arranged two-dimensionally, and (b) a front surface of the electron detecting section is covered with an opening corresponding to each electron detecting element. (C) a plane parallel to the blocking electrode, which is provided between the blocking electrode formed by the conductor grid and the sample and the blocking electrode that two-dimensionally emits electrons from the surface. A two-dimensional electron spectroscopic device characterized in that an electron lens for diffusing inside is provided.