JPH0660873B2 - Luminescence measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the Field to which the Invention Belongs The present invention irradiates a semiconductor crystal with an electron beam and a laser beam, and measures the spectrum of light (luminescence) generated by the irradiation and its intensity. The present invention relates to a luminescence measuring device for analyzing the quality of a semiconductor crystal by fixing impurities, lattice defects and their composites, which are the causes of the spectrum.

(2) Description of conventional technology As a main device for measuring a conventional luminescence spectrum and its intensity, there are a photoluminescence device and a cathodoluminescence device.

The photoluminescence device measures the luminescence by irradiating a sample in a cryogenic state with a laser beam.
These are composed of a laser generator, a liquid He cooling cryostat, a spectroscope and the like. Since it is not necessary to install the sample in a vacuum in terms of equipment, they can be easily assembled by combining the above-mentioned components.

On the other hand, the cathodoluminescence device is a device in which a sample is placed in a vacuum and the sample is irradiated with an electron beam to measure the luminescence. The device is composed of an electron gun, a vacuum container, a spectroscope, etc. Assembling a cathode luminescence device is relatively difficult because the sample is placed in a vacuum and the luminescence generated in the vacuum chamber must be discharged to the atmosphere.

The cathodoluminescence device is characterized in that it is possible to measure the micro region due to the easy convergence of the electron beam, and it is easy to measure the cathodoluminescence image by two-dimensional scanning of the electron beam. The use of cathodoluminescent devices is very small compared to the use of photoluminescent devices due to device limitations.

Under such circumstances, in order to realize the cathodoluminescence measurement and the photoluminescence measurement with the same device, a laser generator, a liquid He cooling cryostat, an electron gun, a vacuum container, an optical system for deriving the luminescence into the atmosphere, Also, a spectroscope or the like is required, but there is no conventional luminescence device having the above-mentioned components at the same time.

The information on the semiconductor crystal quality obtained from the cathodoluminescence measurement and the photoluminescence measurement does not always match, but rather the cathodoluminescence measurement data and the photoluminescence measurement data may have a complementary relationship in the semiconductor crystal evaluation. Therefore, cathodoluminescence measurement and photoluminescence measurement at the same position of the sample may be required.
In this case, the conventional apparatus has a drawback that the sample has to be set again for each of the cathodoluminescence measurement and the photoluminescence measurement, and it is difficult to determine the same position of the sample. Further, when the sample is deteriorated by the electron beam irradiation, the conventional apparatus has a drawback that the deterioration process of the sample under the electron beam irradiation cannot be analyzed in real time by photoluminescence measurement.

(3) Object of the Invention The present invention is characterized in that a cathode luminescence device and a photoluminescence device are realized by the same device,
The purpose is to measure each luminescence independently or simultaneously at the same position of the same sample.

(4) Description of Configuration and Function of the Invention FIG. 1 is a configuration diagram of an embodiment of the present invention. 1 is a vacuum container, 2 is an exhaust system (turbo pump, ion pump, etc.), 3 is an electron gun, 4 is an electron beam optical system, 5 is an objective lens, 6 is a moving cooling table, 7 is a sample, 8 is a cryopanel,
9 is a laser beam generator, 10 is a laser beam focusing system, 1
1 is an optical window, 12 is a mirror, 13 is a luminescence condensing system, 14 is an optical window, 15 is a condensing optical system, 16 is a spectroscope, 17 is a detector, and 18 is a luminescence signal processing system.

In operating these, a high vacuum (for example, 5 × 10 ⁻⁹ Torr to 5 × 10 ⁻¹¹ Torr) is generated in the vacuum container 1 by using an exhaust system 2 including a turbo pump and an ion pump.
To In order to make the inside of the vacuum container 1 a higher vacuum, the vacuum container and the inside have a structure capable of baking. An electron beam emitted from the electron gun 3 is focused by an electron beam optical system 4 and an objective lens 5, and is composed of a sample moving stage, a cooler, and a sample table cooled to a cryogenic temperature by heat conduction from the cooler. The sample 7 placed on the moving cooling table 6 is irradiated.
At this time, a cryopanel 8 is installed around the sample 7 in order to improve the degree of vacuum around the sample and further lower the sample temperature.

A laser beam is generated by using the laser beam generator 9 arranged in the atmosphere, and the laser beam is guided into the vacuum container 1 through the laser beam focusing system 10 and the optical window 11. The condensed laser beam passes under the objective lens 5 via the mirror 12 and is irradiated onto the sample 7 at the same position as the position where the electron beam is obliquely incident.

Luminescence generated from the sample 7 irradiated with the electron beam and the laser beam is placed in the space between the objective lens 5 and the sample 7, and the luminescence condensing system 13 and the optical window 14 are arranged.
Through the atmosphere. Here, the luminescence condensing system 13 is composed of a spheroidal mirror or a combination of a spherical mirror and a plane mirror, and has fine holes through which an electron beam and a laser beam can pass.

The luminescence is transmitted through the condensing optical system 15 to the spectroscope 16
The luminescence of a specific wavelength is detected by the detector 17, and the luminescence signal processing system 18 is used to measure, store, and output the luminescence intensity.

With such a structure, the cathode luminescence generated by electron beam irradiation and the photoluminescence generated by laser beam irradiation can be measured independently at the same position on the same sample. Further, it is possible to irradiate laser light at the same time when measuring the cathode luminescence and change the light amount of the laser light to measure the cathode luminescence. Furthermore, the photoluminescence can be measured by irradiating an electron beam at the same time when measuring the photoluminescence and changing the acceleration energy of the electrons.

FIG. 2 is a device configuration diagram of another embodiment in which the space between the objective lens 5 and the sample 7 is narrow and the luminescence condensing system 13 is arranged on the objective lens 5.
Is a sample, 12 is a mirror, and 13 is a luminescence focusing system.

The optical path of the laser beam is different from that in FIG. That is, the focused laser beam passes through the objective lens 5 via the mirror 12, and is irradiated on the same sample as the position where the electron beam is obliquely incident. At this time, the laser beam is applied to the sample through a gap between the objective lens 5 and the luminescence focusing system 13 or through a hole on the luminescence focusing system 13. The operation and effect of this configuration are the same as in the case of FIG.

1 and 2 are apparatus configuration diagrams for irradiating a sample with a laser beam at an oblique incidence, whereas FIG. 3 shows main portions of an apparatus configuration diagram for irradiating a sample with a laser beam at a normal incidence. Show. 5
Is an objective lens, 6 is a moving cooling table, 7 is a sample, 12 is a mirror, 13 is a luminescence condensing system, and 19 is a sample tilting mechanism. The configuration of FIG. 3 is suitable when the space between the objective lens 5 and the sample 7 is wide.

In order to operate these, the mirror 12 is placed on the electron beam passage axis above or below the luminescence focusing system 13, the axes of the electron beam and the laser beam are aligned, and the laser beam is vertically incident. Irradiate the sample 7. Next, the sample tilting mechanism 19 is adjusted so that the position of the bright spot of the laser beam reflected on the sample 7 coincides with the laser beam emitting point of the laser beam generator. Other operations are the same as those in FIG.

The effect of this configuration diagram is the same as that of the case of Fig. 1, and since the structure is such that the laser beam is vertically incident on the sample, it is possible to eliminate the inclination of the sample surface with respect to the luminescence optical system. When moving in the X-axis and Y-axis directions, the sample surface can always be placed at the focal position of the luminescence optical system.

(5) Description of effects As described above, according to the present invention, the cathode luminescence device and the photoluminescence device are realized by the same device, and therefore, the cathodoluminescence generated by electron beam irradiation and the laser beam irradiation can be realized. The resulting photoluminescence can be measured independently at the same position on the same sample. In addition, by simultaneously irradiating a laser beam during the measurement of cathodoluminescence, excess electrons and holes are generated in the semiconductor crystal that is the sample, and in particular, it is possible to increase the cathodoluminescence intensity of the semi-insulating crystal sample. Therefore, there is an advantage that the cathode luminescence can be measured by changing the light amount of the laser beam.

Furthermore, when measuring photoluminescence, it is possible to analyze the deterioration process of the sample under electron beam irradiation in real time by simultaneously irradiating the electron beam and changing the acceleration energy of the electrons to measure the photoluminescence.

Further, by irradiating the sample with a laser beam at a normal incidence, the sample surface can be always placed at the focal position of the luminescence optical system when the sample moves in the X-axis and Y-axis directions, so that photoluminescence and cathodoluminescence are observed. In the line analysis measurement of 1), there is an advantage that it is not necessary to correct the luminescence intensity due to the deviation from the focus position of the sample surface.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram of an embodiment in which a laser beam is obliquely incident on a sample when the space between the sample and the objective lens is wide, and FIG. 2 is a laser beam when the space between the sample and the objective lens is narrow. FIG. 3 shows a modification of the apparatus configuration diagram for irradiating a sample with oblique incidence, and FIG. 3 shows a modification of the apparatus configuration diagram for irradiating a sample with a laser beam vertically incident. DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Exhaust system, 3 ... Electron gun, 4 ... Electron beam optical system, 5 ... Objective lens, 6 ... Moving cooling stand, 7 ... Sample, 8
... Cryopanel, 9 ... Laser beam generator, 10 ... Laser beam focusing system, 11 ... Optical window, 12 ... Mirror, 13
... Luminescence condensing system, 14 ... Optical window, 15 ... Condensing optical system, 16 ... Spectrometer, 17 ... Detector, 18 ... Luminescence signal processing system, 19 ... Sample tilting mechanism.

Claims (2)

[Claims] 1. A sample moving stage for driving a sample in three XYZ directions, a cooler, a sample stage cooled to an extremely low temperature by heat conduction from the cooler, and a sample surface on the sample stage. An electron gun placed in the Z-axis direction for irradiating a focused electron beam, an electron beam optical system and an objective lens for focusing the electron beam emitted from the electron gun, a window for introducing laser light into the vacuum container,
A luminescence condensing system for arranging a mirror for guiding the laser light introduced into the vacuum container to the sample surface, and further concentrating the luminescence generated from the point where the focused electron beam and the focused laser beam are irradiated. And a window for guiding the condensed luminescence to the outside of the vacuum container are provided inside the high vacuum container, and a laser generator for irradiating a condensed laser beam to the same position where the electron beam is irradiated, and the window The high-vacuum container includes a light-collecting optical system that collects luminescence guided to the outside of a vacuum container, a spectroscope that decomposes the luminescence into a spectrum, a detector that measures the spectrum intensity, and a luminescence signal processing device. A luminescence measuring device provided outside. 2. A mirror for guiding the laser beam to the sample surface has a fine hole through which an electron beam can pass, and by placing the mirror on the passing axis of the electron beam, the axis of the electron beam and the axis of the laser beam can be changed. The luminescence measuring device according to claim (1), characterized in that they are arranged so as to coincide with each other.