Double-light-source oblique incidence semiconductor wafer surface quality detection system

Abstract

The utility model is applicable to the field of optical detection, and provides a double-light-source oblique incidence semiconductor wafer surface quality detection system, which is characterized in that laser of a first laser sequentially passes through a spectroscope, a polaroid, a first convex lens, a diaphragm module and a second convex lens, and obliquely enters the surface of a semiconductor wafer to be detected; and laser of the second laser sequentially passes through the spectroscope, the polaroid, the first convex lens, the diaphragm module and the second convex lens, and obliquely enters the surface of the semiconductor wafer to be measured. The existing optical detection has the defects of small detection field of view, low diffraction resolution and difficulty in positioning, while the characteristics of two detection technologies, namely photoluminescence detection and angle resolution scattering detection, are combined, so that the two detection results can be simply and quickly obtained; and the defect detection of the surface and the subsurface of the semiconductor wafer sample and the quality evaluation detection of the surface roughness are completed.

Description

Technical Field

[0001] The utility model belongs to the field of optical detection, and in particular relates to a semiconductor wafer surface quality detection system with double light sources and oblique incidence. Background Art

[0002] In the production and processing of semiconductor materials, basic processes such as single crystal pulling, slicing, grinding and polishing are usually required to meet the use standards of integrated circuit products. During the grinding and polishing processes, there are complex interactions between the grinding pad, abrasive and the surface of the semiconductor wafer, which leads to surface defects such as pits and scratches on the surface of the semiconductor wafer. For semiconductor wafers, the size of their surface defects is usually quasi-nanometer, which will cause irreversible damage or defects to the precision semiconductor devices produced subsequently. In addition, the surface roughness of semiconductor wafer samples has a direct impact on its adhesion to other materials, wear resistance and fatigue strength. Therefore, the detection equipment and technology for surface quality evaluation of semiconductor wafers have become the focus of optical inspection personnel.

[0003] Existing semiconductor wafer defect detection technologies mainly include scattered dark field imaging, laser confocal microscopy, adaptive filtering imaging, etc., but they have shortcomings such as small detection field of view, low diffraction resolution, and difficulty in positioning. Utility Model Content

[0004] The purpose of the embodiment of the utility model is to provide a semiconductor wafer surface quality detection system with dual light sources and oblique incidence, aiming to solve the shortcomings of small detection field of view, low diffraction resolution and difficulty in positioning.

[0005] The embodiment of the utility model is implemented as follows: a semiconductor wafer surface quality detection system with dual light sources and oblique incidence, the semiconductor wafer surface quality detection system with dual light sources and oblique incidence comprises a first laser, a first beam splitter, a second laser, a polarizer, a first convex lens, an aperture module, and a second convex lens;

[0006] The laser light of the first laser passes through the first beam splitter, the polarizer, the first convex lens, the aperture module and the second convex lens in sequence, and is incident obliquely on the surface of the semiconductor wafer to be tested;

[0007] The laser light of the second laser passes through the first beam splitter, the polarizer, the first convex lens, the aperture module and the second convex lens in sequence, and is incident obliquely onto the surface of the semiconductor wafer to be tested.

[0008] Furthermore, the aperture module includes a pinhole and an aperture stop, and the laser passes through the pinhole and the aperture stop in sequence.

[0009] Furthermore, the semiconductor wafer surface quality detection system with dual light sources and oblique incidence further includes a second spectroscope, a filter, a first detector, and a second detector;

[0010] The laser light of the first laser generates a scattering phenomenon on the surface of the semiconductor wafer to be tested, and enters the first detector through the second spectrometer; the laser light of the second laser generates a photoluminescence phenomenon on the surface of the semiconductor wafer to be tested, and enters the second detector through the second spectrometer and the filter in sequence.

[0011] Furthermore, the tilt angle of the light entering the surface of the semiconductor wafer to be tested is 20 degrees.

[0012] Furthermore, the semiconductor wafer surface quality inspection system with dual light sources and oblique incidence further includes a light-absorbing material shell, which is arranged on the outside of all components of the semiconductor wafer surface quality inspection system with dual light sources and oblique incidence.

[0013] Furthermore, the semiconductor wafer surface quality inspection system with dual light sources and oblique incidence further includes a computer module, which determines whether a defect exists based on the detection results of the first detector and the second detector.

[0014] The embodiment of the present invention provides a semiconductor wafer surface quality inspection system with dual light sources and oblique incidence. By combining the characteristics of two detection technologies, photoluminescence detection and angle-resolved scattering detection, the optical path is constructed and optimized. The results of the two detections can be obtained simply and quickly, and the defect detection and surface roughness quality evaluation detection of the surface and sub-surface of semiconductor wafer samples can be completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a photoluminescence principle diagram of an embodiment of the present utility model;

[0016] Figure 2 This is a structural diagram of a semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of angle-resolved scattering intensity according to an embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of photoluminescence according to an embodiment of the present invention.

[0019] Figure Number:

[0020] Light-absorbing material housing 1, first laser 2, first beam splitter 3, second laser 4, polarizer 5, first convex lens 6, pinhole 7, aperture stop 8, second convex lens 9, semiconductor wafer surface to be measured 10, second beam splitter 11, first detector 12, filter 13, second detector 14. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] It will be understood that the terms "first," "second," etc. used herein may be used to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element.

[0023] Figure 1 This is a diagram of the principle of photoluminescence. Photoluminescence refers to the process by which a sample, when stimulated by excitation light, absorbs photons (or electromagnetic waves) and then re-radiates them. This process also releases phonons, which carry away some of the energy. As a result, the emitted light carries less energy and has a longer wavelength than the excitation light. Semiconductors are the most common photoluminescent materials. Defects or impurities in a sample alter the original energy level distribution in that region, resulting in photoluminescence characteristics that differ from those of a normal sample. Because shorter laser wavelengths provide greater penetration, photoluminescence can also detect subsurface defects in semiconductor wafer samples. Angular-resolved scattering detection involves incident laser light at a specific angle on the component surface. A detector collects the angularly distributed scattered intensity, modulated by the sample's microscopic surface topography. This quantifies the scattering characteristics of the sample's surface topography and, by analyzing their correlation with the surface topography, enables inversion of the sample's surface topography.

[0024] like Figure 2 As shown, in one embodiment, a dual-light source oblique-incidence semiconductor wafer surface quality inspection system is provided. The dual-light source oblique-incidence semiconductor wafer surface quality inspection system includes: a light-absorbing material housing 1, a first laser 2, a first beam splitter 3, a second laser 4, a polarizer 5, a first convex lens 6, a pinhole 7, an aperture stop 8, a second convex lens 9, a second beam splitter 11, a filter 13, a first detector 12, and a second detector 14.

[0025] The first laser 2 and the second laser 4 are respectively a visible light laser and an ultraviolet laser, and their positions can be interchanged. Visible light lasers correspond to angle-resolved scattering detection, and ultraviolet lasers correspond to photoluminescence detection. In the embodiment, the first laser 2 is a visible light laser, and the second laser 4 is an ultraviolet laser. The first detector 12 and the second detector 14 are detectors such as CCD and CMOS that can collect light intensity information and image data. In preliminary work, simulation methods have verified that during angle-resolved scattering detection, the incident light is in the s-polarization state, and the resulting scattered signal intensity is higher, which is conducive to data collection and defect identification. Therefore, it is chosen to add a polarizer 5 in the optical path to convert the polarization state of the incident light into the s-polarization state.

[0026] When performing angle-resolved scattering detection, the light beam from the first laser 2 is transmitted through the first beam splitter 3. The light beam passes through the polarizer 5 and is converted into s-polarized light with a polarization vector perpendicular to the incident plane. The light beam is then focused by the first convex lens 6 and incident on the pinhole 7 at the focal position of the first convex lens 6. The pinhole 7 filters out some stray light. At the same time, the light beam is diffracted through the pinhole 7. The aperture diaphragm 8 only allows the 0th-order diffracted light to pass through, thereby obtaining a high-quality s-polarized laser beam. The 0th-order diffracted light is focused by the second convex lens 9 and is obliquely incident on the surface 10 of the semiconductor wafer to be tested at an incident angle of 20°, causing scattering. The light-absorbing material shell 1 will limit only the scattered light within a preset angle range to enter the collection light path. The light transmitted through the second beam splitter 11 will be incident on the surface of the first detector 12, thereby collecting the angle-resolved scattering intensity map of the sample surface.

[0027] During photoluminescence testing, the beam from the second laser 4 is reflected by the first beam splitter 3 and then passes through the polarizer 5, converting it into s-polarized light with a polarization vector perpendicular to the plane of incidence. The beam is then focused by the first convex lens 6 and incident on a pinhole 7 at the focal point of the first convex lens 6. The pinhole 7 filters out some stray light. Simultaneously, the beam is diffracted by the pinhole 7. The aperture 8 is shifted to allow only the 0th-order diffracted light to pass through, thus producing a high-quality s-polarized laser beam. The 0th-order diffracted light is focused by the second convex lens 9 and incident obliquely on the surface 10 of the semiconductor wafer to be tested at an angle of 20°. This scattering simultaneously excites defects in the sample to produce photoluminescence. The light-absorbing material housing 1 restricts light within a set angle range from entering the collection optical path and being reflected by the second beam splitter 11. The purpose of this testing is to analyze the photoluminescence image. Therefore, a filter 13 is installed before the second detector 14 to filter out scattered light within the original wavelength band, allowing the second detector 14 to capture the photoluminescence image of the defect. Different types of defects will emit light of different wavelengths when excited by laser of the same wavelength, which can be used to distinguish the types of defects.

[0028] In the same detection area, surface particles, scratches and subsurface dislocation defects appear in the field of view at the same time. The angle-resolved scattering intensity diagram collected by the first detector 12 and the photoluminescence diagram collected by the second detector 14 are shown in Figure 2. Figure 3 and Figure 4 As shown. Figure 3 In the angle-resolved scattering intensity diagram, surface particles and scratch defects significantly change the scattered light intensity distribution in their respective areas and surrounding areas, and can be clearly observed. The dotted box on the right refers to the undetected triangular dislocation defect on the subsurface of the sample. Figure 4 In the photoluminescence diagram, in addition to the obvious surface particles and scratch defects, triangular dislocation defects in the sub-surface can also be detected, thus achieving more comprehensive defect detection.

[0029] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A semiconductor wafer surface quality inspection system with dual light sources and oblique incidence, characterized in that: The semiconductor wafer surface quality detection system with dual light sources and oblique incidence includes a first laser, a first beam splitter, a second laser, a polarizer, a first convex lens, an aperture module and a second convex lens; The laser light of the first laser passes through the first beam splitter, the polarizer, the first convex lens, the aperture module and the second convex lens in sequence, and is incident obliquely on the surface of the semiconductor wafer to be tested; The laser light of the second laser passes through the first beam splitter, the polarizer, the first convex lens, the aperture module and the second convex lens in sequence, and is incident obliquely onto the surface of the semiconductor wafer to be tested.

2. The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to claim 1, characterized in that: The aperture module includes a pinhole and an aperture stop, and the laser passes through the pinhole and the aperture stop in sequence.

3. The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to claim 1, characterized in that: The semiconductor wafer surface quality detection system with dual light sources and oblique incidence further includes a second spectroscope, a filter, a first detector and a second detector; The laser light of the first laser is scattered on the surface of the semiconductor wafer to be tested and enters the first detector through the second beam splitter; The laser light from the second laser generates a photoluminescence phenomenon on the surface of the semiconductor wafer to be measured, passes through the second beam splitter and the filter in sequence, and enters the second detector.

4. The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to claim 1, characterized in that: The tilt angle of the light entering the surface of the semiconductor wafer to be tested is 20 degrees.

5. The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to any one of claims 1 to 4, characterized in that: The semiconductor wafer surface quality detection system with dual light sources and oblique incidence further comprises a light-absorbing material shell, which is arranged outside all components of the semiconductor wafer surface quality detection system with dual light sources and oblique incidence.

6. The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence according to claim 3, characterized in that: The semiconductor wafer surface quality inspection system with dual light sources and oblique incidence further includes a computer module, which determines whether there is a defect based on the detection results of the first detector and the second detector.

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