JPH0835934A - Internal-flaw evaluation apparatus of sample - Google Patents

Abstract

PURPOSE:To provide an internal-flaw evaluation apparatus by which photoluminescence light(PL) from a specific depth position at the inside of a sample is measured comparatively simply and which can evaluate a flaw at the inside of the sample regarding an apparatus which evaluates the internal flaw of the sample by means of the photoluminescence light. CONSTITUTION:The focal position at the inside of a sample 16 which condenses exciting light 10 from an exciting light source 11 so as to generate PL corresponds to a position which condenses the PL so as to be passed, i.e., a position in which a pinhole 19a has been formed. As a result, only the PL from the focal position of the sample 16 is guided surely to a detection device 27 so as to be capable of evaluating it. Then, the relative distance between a lens 15 (a first lens means) and the sample 16 is changed, and its focal position is changed. Thereby, only the PL from a specific depth position in the sample 16 can be detected with good efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal defect evaluation apparatus for evaluating internal defects of a sample such as a semiconductor wafer having a multilayer structure.

[0002]

2. Description of the Related Art Generally, photoluminescence light (hereinafter referred to as P
L) is the luminescence observed when the electron / hole pairs generated inside the sample are recombined when the sample is irradiated with the excitation light from the excitation light source. The wavelength of this PL reflects the state of electrons and holes in the sample, and the PL can be spectrally analyzed to examine the physical properties of the sample in detail. Therefore, as a conventional device for obtaining information concerning the depth direction by PL from the inside of the sample, for example, Japanese Patent Laid-Open No.
The one disclosed in JP-A-264468 is known. In the device disclosed in the above publication, as shown in FIG.
The laser light 51 (excitation light) is emitted from a laser light source (excitation light source) (not shown) at an angle β with respect to the surface of the. The laser light 51 is refracted at the surface at a refraction angle α when entering the sample 50, and the PL in the sample 50 generated by the refracted laser light is θ with respect to the normal direction of the sample 50. It is collected by a lens 52 arranged at an angle and detected by a detector 53. The above P that occurred
L varies depending on the depth positions 50a to 50d in the sample 50, and the positions 54a to 54d in the visual field 54 in the detector 53 are detected differently. It is possible to obtain information about physical properties related to the depth position.

[0003]

However, in such a conventional apparatus, as described above, the laser beam 51 is applied to the sample 50.
Since the PL generated by the laser beam incident on the surface of the sample 50 at the angle β and refracted at the angle α needs to be condensed by the lens 52 arranged at θ with respect to the normal direction of the surface of the sample 50. However, these angles β, α, and θ must be set or measured accurately, and a lot of time is required for measuring PL. Further, since the refraction angle α differs depending on the target sample, it is impossible to accurately obtain the absolute value of the depth position to the converging point for these different samples. Therefore, the present invention was devised in view of the above circumstances, and an internal defect evaluation apparatus capable of evaluating PL from a specific depth position inside a sample and evaluating internal defects of the sample relatively easily. The purpose is to provide.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is the gist of the invention. Photoluminescence light generated by irradiating a sample with excitation light from an excitation light source. In the device for detecting internal defects of the sample by detecting
A first lens means disposed on the optical path of the photoluminescent light from the sample with its optical axis oriented in the direction normal to the surface of the sample; and the first lens means relative to each other in the optical axis direction of the photoluminescent light. Moving means for moving the first lens means, second lens means for condensing the light passing through the first lens means, and the photodetector light from the focus position of the first lens means, which are provided together with the detecting device. Is an internal defect evaluation apparatus for a sample according to a point including a mask means for passing the light toward the detection apparatus.

[0005]

In the internal defect evaluation apparatus having the above structure, the focal point inside the sample where the excitation light from the excitation light source is condensed and the PL is generated and the position where the PL is condensed and passed, that is, the pinhole is formed. Since it corresponds to the position provided, it is possible to reliably guide only the PL from the focal position of this sample to the detection device and evaluate it. Then, by changing the relative distance between the first lens means and the sample to change the focal position thereof, only the PL from a specific depth position in the sample can be efficiently detected.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. 1 is a block diagram showing a schematic structure of an internal defect evaluation apparatus for a sample according to an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of the internal defect evaluation apparatus, and FIG. 3 is a first lens means. And Fig. 4 is an explanatory view of obtaining information by changing the depth position inside the sample by changing the relative distance between the sample, Fig. 4 is a bluff showing an example of PL observed by the internal defect evaluation device, and Fig. 5 is a book. It is explanatory drawing which shows the principal part structure of the internal defect evaluation apparatus which concerns on the other Example of this invention. In the internal defect evaluation apparatus according to this embodiment, as shown in FIGS.
Excitation light source 11, concave lens 8, lens 9, plate 12 provided with pinhole 12a, lens 1 in the direction normal to the surface of sample 16 fixed on stage 17.
3, a beam splitter 14, and a lens 15 (first lens means) are arranged. As the excitation light source 11,
For example, an Ar laser is used, and the excitation light 10 from the excitation light source 11 is applied to the surface of the sample 16. The lens 15 has a function of condensing the excitation light 10 in the sample 16 and making photoluminescence light (hereinafter PL) from the focal position into parallel light.
On the other hand, the lens driving device 25 (moving means) is driven to move in the optical axis direction of the PL. The lens driving device 25 is controlled by the control device 22 including a computer that controls the internal defect evaluation device. In this case, the lens 15 may be fixed and the XY stage 17 may be moved and driven in the optical axis direction of the PL with respect to the lens 15 to change the relative distance between the lens 15 and the sample 16. By doing so, the XY stage 17 can move and adjust the sample 16 in the three-dimensional space by the control device 22.

In the direction perpendicular to the optical axis of the PL of the beam splitter 14, the band-pass filter 26, the lens 18 (second lens means), the mask 19 (mask means) provided with the pinhole 19a, and the detector. 27 are provided. The lens 18 is PL2 passing through the lens 15.
The mask 19 is attached such that the pinhole 19a is located at the focusing position of the lens 15 so that only the PL from the focal position of the lens 15 passes through the detecting device 27. (See Figure 2). The detection device 27 attached to the mask 12 is the spectroscope 2
0 and a detector 21 and connected to the control device 22. Further, an image output device 23 for analysis is connected to the control device 22. The internal defect evaluation apparatus according to this example is configured as described above. Therefore, in the evaluation apparatus having the above-described configuration, the excitation light 10 emitted from the excitation light source 11 is expanded by the concave lens 8 and once converged by the lens 9, and passes through the pinhole 12a of the plate 12 to produce the sample 16 Light other than the excitation light that generates a predetermined PL is removed. Then, the excitation light 10 is made into parallel rays by the lens 13. Excitation light 10 converted into parallel rays as described above
Further passes through the beam splitter 14 and the lens 15
Are converged by and are narrowed down on the surface of the sample 16.
The PL generated in the sample 16 by being irradiated with the excitation light 10 in this manner is condensed by the lens 15 and becomes a parallel light beam. That is, this parallel light beam is PL from the focus position in the sample 16, and the beam splitter 1
The course is changed by 4. Then, the parallel rays are converged by the lens 18 after only a predetermined PL is transmitted by the action of the band pass filter 26. As described above, the pinhole 12 is provided at the focusing position by the lens 18.
Since a is provided, only the PL from the focus position in the sample 16 is incident on the spectroscope 20 to be spectroscopically separated and detected by the detector 21.

That is, a focus position inside the sample 16 where the excitation light from the excitation light source 11 is collected and PL is generated and a position where this PL is collected and passed, in other words, a pinhole 19a is provided. Since the positions correspond to each other, the PL generated at a position other than the focal position in the sample 16 which does not become a parallel light beam by the lens 15 is not converged by the lens 18 at the position of the pinhole 19a and is guided to the spectroscope 20. Absent. Therefore, only the PL from the focus position of the sample 16 can be surely guided to the detection device 27 and evaluated. Then, by moving the lens 15 in the optical axis direction of the PL by the lens driving device 25 to change the focal position with respect to the sample 16, only the PL from a specific depth position in the sample 16 can be efficiently detected. You can As a result, according to the apparatus, when the information about the predetermined position in the depth direction is obtained by PL from the inside of the sample 16, the incident angle of the excitation light, as in the case of the conventional apparatus,
Only the PL from a predetermined depth position in the sample can be detected without measuring the refraction angle or the directional angle for observing the PL. Further, even in the case of different kinds of samples, the PL at a predetermined depth position can be measured in the same manner as in the above case only by changing the relative distance between the sample and the lens 15. Sample 16 in FIG.
2 shows a situation in which PL is measured by changing the depth position of. Further, in the device according to the present embodiment, the XY stage 17 supporting the sample 16 is driven and controlled by the control device 22 to measure the PL while moving the sample 16 in the XY plane. Thereby, the PL applied to the two-dimensional direction at the predetermined depth position can be easily measured.

Here, when a multilayer structure of Si crystal is used as the sample to be measured, it is desirable to use a waveform of 400 nm to 1000 nm as the excitation light, that is, the excitation light of the wavelength of 400 nm was used. In this case, the penetration depth of this excitation light into the sample is 0.1 μm, and with excitation light of a shorter wavelength, PL from the inside of the sample
Cannot be measured efficiently. Also, the wavelength is 1μ
This is because when the excitation light longer than m is used, the energy of the excitation light is small, so that sufficient electrons and holes cannot be generated inside the sample. At this time,
An example of observed PL is shown in FIG. That is, the wavelength of 1000 nm to 1700 nm in the sample due to the excitation light.
Although PL is generated within the range, the band edge emission reflecting the crystallinity of the sample and the emission due to the defect in the sample are clearly observed. Therefore, the depth position of the defect inside the sample can be known by determining the depth position of such light emission by the device. FIG. 5 shows a main configuration of an internal defect evaluation apparatus according to another embodiment of the present invention. That is, in the above-described embodiment, the excitation light is incident on the surface of the sample 16 from the normal direction thereof, but as shown in FIG. 16 Excitation light 1 obliquely to the surface normal direction
0'may be made incident. Further, in place of the spectroscope 20 in the above embodiment, the PL of the wavelength to be obtained is
It is also possible to use a so-called narrow band transmission filter that transmits the light.

[0010]

INDUSTRIAL APPLICABILITY As described above, the present invention is an apparatus for detecting photoluminescence light generated by irradiating a sample with excitation light from an excitation light source by means of a detector to evaluate internal defects in the sample, A first lens means disposed on the optical path of the photoluminescent light from the sample with its optical axis oriented in the direction normal to the surface of the sample; and the first lens means relative to each other in the optical axis direction of the photoluminescent light. Moving means for moving the first lens means, second lens means for condensing the light passing through the first lens means, and the photodetector light from the focus position of the first lens means, which are provided together with the detecting device. Since it is a device for evaluating internal defects of a sample, the device is provided with a mask means for passing the sample toward the detection device. It can be evaluated internal defects of the sample by measuring the PL.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a sample internal defect evaluation apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the internal defect evaluation apparatus.

FIG. 3 is an explanatory diagram of a case where information is obtained by changing the depth position inside the sample by changing the relative distance between the first lens means and the sample.

FIG. 4 is a PL observed by the internal defect evaluation apparatus.
Bluff showing an example.

FIG. 5 is an explanatory diagram showing the main configuration of an internal defect evaluation apparatus according to another embodiment of the present invention.

FIG. 6 is a principal block diagram showing a schematic configuration of a conventional internal defect evaluation apparatus.

[Explanation of symbols]

 10, 10 '... Excitation light 11 ... Excitation light source 14 ... Beam splitter 15 ... Lens (first lens means) 16 ... Sample 17 ... XY stage 18 ... Lens (second lens means) 19 ... Mask (mask means) ) 19a ... pinhole 20 ... spectroscope 21 ... detector 22 ... control device 24 ... PL 25 ... lens drive device (moving means) 27 ... detection device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Morimoto 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel Works, Ltd. Kobe Research Institute

Claims (1)

[Claims] 1. A device for detecting photoluminescence light generated by irradiating a sample with excitation light from an excitation light source by a detection device to evaluate internal defects of the sample, wherein light of photoluminescence light from the sample is detected. First lens means arranged on the road with its optical axis oriented in the direction normal to the sample surface; moving means for relatively moving the first lens means in the optical axis direction of the photoluminescent light; A second lens means for condensing light passing through the first lens means, and the detection device are provided side by side, and only the photoluminescent light from the focal position of the first lens means is passed toward the detection device. An internal defect evaluation apparatus for a sample, comprising a mask means.