Wafer photoluminescence multi-point detection device and method

Abstract

The invention discloses a wafer photoluminescence multi-point detection device and method, and the device comprises a carrying platform which is used for carrying a to-be-detected sample; a light source module, a spectral measurement module, a tube lens, an optical fiber probe and an optical fiber path; wherein the optical fiber optical path is connected with the optical fiber probe and the spectral measurement module; the optical fiber probe is of an array structure, and the spectrum measurement module can achieve multi-channel spectrum detection. The multi-channel spectrum measurement module is utilized, so that the photoluminescence spectrums of a plurality of point positions can be measured at the same time, and the photoluminescence detection efficiency is improved.

Description

Technical Field

[0001] The present invention mainly relates to semiconductor wafer detection, in particular to a wafer photoluminescence multi-point detection device and method. Background Art

[0002] With the development of technology, semiconductor technology is increasingly widely used in daily life. Semiconductor production has different, complex, and numerous process stages / processes from beginning to end. Due to the complexity of the process and the large number of procedures, each stage requires strict quality inspection and assessment instruments and methods. For example, at the wafer stage, semiconductors need to be inspected for appearance defects or photoluminescence measurements. This intercepts defective products in the process stage to prevent them from continuing to flow into subsequent process stages and affecting the product yield. At the same time, discovering defects can also promote process improvement and optimization.

[0003] In the semiconductor wafer inspection stage, photoluminescence measurement is currently one of the mainstream inspection methods. Using a wavelength greater than the semiconductor bandgap width to excite the semiconductor wafer sample, the light can be excited. For abnormal wafers, the shape of the luminescence spectrum is different from that of normal wafers. The fluorescence intensity, peak wavelength, half-width, etc. are all key parameters to characterize the wafer quality.

[0004] The current spectral measurement technology can only measure one point at a time, such as Figure 1 This is not enough to obtain the spectrum of the entire field of view, and thus cannot well characterize the quality of each position of the wafer. Another way is to use a displacement platform to gradually scan and measure the spectrum of each point, but this is very inefficient. Summary of the invention

[0005] In view of at least one defect or improvement need of the prior art, the present invention provides a wafer photoluminescence multi-point detection device and method, which utilizes a multi-channel spectrum measurement module to simultaneously measure the photoluminescence spectra of multiple points, thereby improving the efficiency of photoluminescence detection.

[0006] To achieve the above object, according to a first aspect of the present invention, a wafer photoluminescence multi-point detection device is provided, the device comprising: A stage for carrying a sample to be tested; a light source module for emitting monochromatic light to illuminate the surface of the sample to be tested along a first optical path; a spectrum measurement module, an optical fiber probe, an optical fiber optical path, and a tube lens arranged along a second optical path; wherein the optical fiber optical path connects the optical fiber probe and the spectrum measurement module; the optical fiber probe is an array structure, and the spectrum measurement module can realize multi-channel spectrum detection; the tube lens at least includes an objective lens arranged on a side close to the sample to be tested; The optical fiber probe is used to receive fluorescence emitted by multiple points on the surface of the sample to be tested after being excited by the monochromatic light and transmitted along the second optical path; the tube lens is used to image the fluorescence at the optical fiber probe; the spectrum measurement module is used to receive the fluorescence received by the optical fiber probe and transmitted along the optical fiber optical path, and simultaneously perform photoluminescence spectrum detection on multiple points on the surface of the sample to be tested.

[0007] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The spectrum measurement module is a multi-channel spectrometer, or a plurality of single-channel spectrometers, or a plurality of single-channel spectrometers and a multi-channel spectrometer in common.

[0008] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The first displacement module controls the optical fiber probes so that all the optical fiber probes are located at the image plane of the tube mirror.

[0009] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The first displacement module controls the optical fiber probe to move a first displacement along the optical axis direction of the tube mirror.

[0010] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The spectrum measurement module is a first spectrum measurement module and a second spectrum measurement module, the optical fiber optical path includes a first optical fiber optical path and a second optical fiber optical path, and the optical fiber probe includes a corresponding first optical fiber probe and a second optical fiber probe; It also includes a first spectroscopic module, which is arranged inside the tube lens; the fluorescence follows the second optical path, is split by the first spectroscopic module, and then enters the first spectrum measurement module and the second spectrum measurement module through the first optical fiber optical path and the second optical fiber optical path respectively.

[0011] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The second displacement module controls the relative positions of the first fiber optic probe and the second fiber optic probe so that the first fiber optic probe and the second fiber optic probe are offset by a second displacement.

[0012] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: A second light splitting module is arranged inside the tube lens; After the monochromatic light enters the tube lens, it follows the first optical path, passes through the second spectroscopic module and the objective lens, and irradiates the surface of the sample to be tested; after the fluorescence enters the tube lens through the objective lens, it passes through the second spectroscopic module and is imaged at the optical fiber probe.

[0013] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: The camera module is used to receive imaging light from the surface of the sample to be tested and take photos and perform 3D measurements on the surface of the sample to be tested.

[0014] Furthermore, the above-mentioned wafer photoluminescence multi-point detection device further includes: A third light splitting module is arranged inside the tube lens; The camera module, the third spectroscopic module and the objective lens are sequentially arranged along the third optical path, and are used to receive imaging light of the surface of the sample to be tested transmitted along the third optical path, and take photos and perform 3D measurements on the surface of the sample to be tested; the third optical path is partially coaxial with the second optical path; the third spectroscopic module is used to separate the third optical path from the second optical path.

[0015] According to a second aspect of the present invention, a wafer photoluminescence multi-point detection method is also provided, using the above-mentioned wafer photoluminescence multi-point detection device, comprising: The light source module emits monochromatic light to illuminate the surface of the sample to be tested along a first light path; Adjusting the position of the optical fiber probe so that the optical fiber probe is located at a predetermined position; The optical fiber probe receives the excitation light generated by the sample to be tested after receiving the monochromatic light, and enters the spectrum measurement module along the optical fiber light path to realize multi-channel photoluminescence spectrum detection.

[0016] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art: (1) The present invention provides a wafer photoluminescence multi-point detection device and method, which utilizes a multi-channel spectrum measurement module to simultaneously measure the photoluminescence spectra of multiple points, thereby improving the efficiency of photoluminescence detection; (2) The present invention provides a wafer photoluminescence multi-point detection device and method, in which a fiber optic probe is arranged to be movable along the optical axis, which can effectively increase the measurement space area and overall characterize the photoluminescence spectrum characteristics in the entire area; (3) The present invention provides a wafer photoluminescence multi-point detection device and method, which utilizes the characteristics of the infinite imaging system to split the light path and place different optical fiber arrays at different positions on its conjugate surface to further expand the measurement points. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of a wafer photoluminescence multi-point detection device in the prior art; Figure 2 A schematic diagram of a wafer photoluminescence multi-point detection device provided by an embodiment of the present invention; Figure 3 A schematic diagram of another wafer photoluminescence multi-point detection device provided by an embodiment of the present invention; Figure 4 A schematic diagram of another wafer photoluminescence multi-point detection device provided by an embodiment of the present invention; Figure 5 A schematic diagram of the staggered displacement of an optical fiber array provided in an embodiment of the present invention; Figure 6 A schematic diagram of another wafer photoluminescence multi-point detection device provided by an embodiment of the present invention; Figure 7 A schematic diagram of another wafer photoluminescence multi-point detection device provided by an embodiment of the present invention; Figure 8 A schematic diagram of another wafer photoluminescence multi-point detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] 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 in conjunction with 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. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] The terms "first", "second", "third", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0021] like Figure 2As shown, as a first embodiment of the present invention, a wafer photoluminescence multi-point detection device is provided, which includes two optical paths, wherein the first optical path is a monochromatic light path used in photoluminescence spectrum detection, and the second optical path is a fluorescence path generated by the wafer to be tested in photoluminescence spectrum detection.

[0022] Photoluminescence (PL) is a method of irradiating the surface of a wafer to be tested with monochromatic light. Semiconductor materials will emit fluorescence in response to monochromatic light. If there are defects on the surface of the wafer, the fluorescence spectrum at the defect will be different from that at the normal location. By detecting the fluorescence spectrum, the performance of the wafer can be detected. For the photoluminescence spectrum detection method, the following prior art documents can also be referred to: "Microwave-induced patterns in n-GaAs and their photoluminescence imaging" by Bel'kov, VV et al. (Physical Review B, Vol. 61, No. 20, The American Physical Society, May 15, 2000, pp. 13698-13702) and "Development of a UV scanning photoluminescence apparatus for SiC characterization" by Masarotto et al. (Eur J AP 20, 141-144, 2002).

[0023] Based on the above principle, Figure 2 As shown, the first optical path provided in this embodiment includes a light source module 1, and the second optical path provided includes a spectrum measurement module 2 that can realize multi-channel measurement, and an optical fiber optical path 3 and an optical fiber probe 5 of the spectrum measurement module 2. Among them, the light source module 1 emits monochromatic light as light to excite the wafer surface, and the spectrum measurement module 2 receives the fluorescence generated by the wafer surface to perform photoluminescence spectrum detection.

[0024] In this embodiment, a tube lens 10 is also provided. The structure of the tube lens 10 is similar to that of a microscope, and is an imaging system, including an objective lens 8 close to a side of the sample 7 to be tested, and also including a corresponding support structure and other imaging lens group structures. All lens group structures of the tube lens 10, including the objective lens 8, should be coaxial, that is, share a common optical axis. In actual application, all lens groups in the tube lens 10, including the objective lens 8, should be adjusted to be coaxial before being used for spectral detection of wafer photoluminescence. The specific structures of other lens groups can be specifically designed according to the needs, and will not be repeated in this embodiment.

[0025] The tube lens 10 can image the fluorescence emitted by the sample 7 to be tested at a certain image plane. Therefore, when the optical fiber probe 5 is set at the image plane of the tube lens 10, the fluorescence generated by the sample 7 to be tested can be focused on the optical fiber probe 5.

[0026] like Figure 3 As shown, for the optical fiber probe 5, a part of the optical fiber probe or all the optical fiber probes 5 can also be set to move a certain displacement along the optical axis direction. For the optical fiber probe 5 that is not at the image plane, what is measured at this time is the spectrum set of a small area in the object plane, which can effectively increase the measured spatial area and overall characterize the photoluminescence spectrum characteristics in the entire area.

[0027] The spectrum measurement module 2 can be set in a variety of ways, for example, it can be a multi-channel spectrometer, it can also be a plurality of single-channel spectrometers, or it can be any combination of the above two spectrometers, as long as it can realize multi-channel spectrum luminescence detection. For the optical fiber light path 3 and optical fiber probe 5 that are set up in conjunction with it, the number of optical fiber light paths and the corresponding number of optical fiber probes should be the same as the number of channels of the spectrum measurement module 2, so that each measurement channel of the spectrum measurement module 2 can have a corresponding optical fiber light path 3 and optical fiber probe 5. Correspondingly, the optical fiber probe 5 is an array structure, which can realize the simultaneous collection of spectral information of photoluminescence at multiple points, and can ensure that the optical path of the multi-channel fluorescence received by multiple spectrum measurement modules 2 is the same in space, avoiding errors.

[0028] At the same time, the monochromatic light emitted by the light source module 1 should be able to simultaneously excite multiple points on the surface of the sample 7. The light source module 1 can be configured, for example, as a multi-channel light source, or a combination of multiple single-channel light sources, or a light source with a certain beam width, or other similar structures.

[0029] The light source module 1 may not be limited to irradiating the surface of the sample 7 to be tested. Figure 2 As shown, illuminating the surface of the sample 7 to be tested from the side will not affect the detection of its fluorescence.

[0030] The array of the optical fiber probes 5 is preferably a square array, for example, a 3×3 or 4×4 square array. It is also not limited to a square array structure. For example, the optical fiber probes 5 can be arranged in a circular shape, arranged at a certain distance, or can be arranged in a triangular shape. Those skilled in the art can arrange the specific shape as needed.

[0031] The current spectral measurement technology can only measure one point at a time, such as Figure 1In this way, it is not enough to obtain the spectrum of the entire field of view, and thus it is not possible to characterize the quality of each position of the wafer. Another way is to use a displacement platform to gradually scan and measure the spectrum of each point, but this is very inefficient. In the present invention, a multi-channel light source module 1 is used to simultaneously emit multi-channel light to simultaneously excite multiple points on the surface of the sample 7 to be tested, and a spectrum measurement module 2 is used to simultaneously measure the fluorescence of multiple points, thereby improving the efficiency of photoluminescence detection.

[0032] In order to further improve the efficiency of multi-channel measurement, a second set of spectrum measurement modules and optical fiber optical paths can be set up. Figure 4 As shown, a first spectrum measurement module 21 and a second spectrum measurement module 22, as well as a first optical fiber optical path 31, a second optical fiber optical path 32, a first optical fiber probe 51, and a second optical fiber probe 52 matched therewith can be provided. After the second set of spectrum measurement modules and optical fiber optical paths are provided, a spectrometer module should also be provided to split the fluorescence and distribute it to the two sets of spectrum measurement modules. In this embodiment, the first spectrometer module 41 is provided to achieve the above effect. After the fluorescence on the surface of the sample 7 to be tested is split by the first spectrometer module 41, it enters the first spectrum measurement module 21 and the second spectrum measurement module 22 respectively along the first optical fiber optical path 31 and the second optical fiber optical path 32 from the first optical fiber probe 51 and the second optical fiber probe 52, so that multiple points on the surface of the sample 7 to be tested can be measured.

[0033] As a specific implementation method, Figure 5 As shown, the first fiber optic probe 51 and the second fiber optic probe 52 are both 3×3 square arrays, and the distance between adjacent fiber optic probes is 2d. The first fiber optic probe 51 and the second fiber optic probe 52 can be controlled by the displacement module to stagger the displacement d, which can improve the efficiency of the photoluminescence spectrum detection of the surface of the sample 7 to be tested. When the first fiber optic probe 51 and the second fiber optic probe 52 are not staggered by a certain displacement, they measure the photoluminescence spectra of the same 9 points on the surface of the sample 7 to be tested. After the first fiber optic probe 51 and the second fiber optic probe 52 are staggered by displacement d, the first fiber optic probe 51 and the second fiber optic probe 52 respectively measure 9 different points on the surface of the sample 7 to be tested, that is, the first spectrum measurement module 21 and the second spectrum measurement module 22 can simultaneously measure the photoluminescence spectra of 18 points in total, further improving the efficiency of spectrum detection.

[0034] In order to obtain the best fluorescence imaging effect, the first fiber optic probe 51 and the second fiber optic probe 52 should be arranged on the image plane of the tube mirror 10. That is, the first fiber optic probe 51 and the second fiber optic probe 52 are located at the conjugate plane of the image plane of the tube mirror 10. When the first fiber optic probe 51 and the second fiber optic probe 52 need to be staggered by a certain displacement, it is necessary to control them to stagger by a first displacement on the conjugate plane.

[0035] As another specific implementation, Figure 6 As shown, the first optical path and the second optical path are set as coaxial optical paths, and both the first optical path and the second optical path are confined within the tube lens 10, and a second spectroscopic module 42 is set in the tube lens 10 to redirect the first optical path, that is, the second spectroscopic module 42 can separate the first optical path and the second optical path.

[0036] Furthermore, the surface of the sample 7 to be tested can be photographed and tested in 3D. Figure 7 As shown, the camera module 9 is set to directly photograph the morphology of the surface of the sample 7 to be tested. In order to obtain a better photographing effect, the camera module 9 should be directly photographing the sample 7 to be tested. Therefore, it can be as follows Figure 8 As shown, by arranging the third light splitting module 43 inside the tube lens, the camera module 9 can realize vertical photography of the sample 7 to be tested, thereby obtaining a better photography effect.

[0037] The present invention is not limited to the implementations given in this embodiment. For example, the stage 6 of the present invention may be a movable stage, and the present invention may further include an automatic focusing device, which can realize the focusing of the objective lens 8 by moving the position of the stage 6, thereby improving the detection resolution.

[0038] As another embodiment of the present invention, a wafer photoluminescence multi-point detection method is provided, using the above-mentioned wafer photoluminescence multi-point detection device, comprising: The light source module 1 emits monochromatic light to illuminate the surface of the sample 7 to be tested along a first light path; Adjusting the position of the optical fiber probe 5 so that the optical fiber probe 5 is located at a predetermined position; The optical fiber probe 5 receives the excitation light generated by the sample to be tested 7 after receiving the monochromatic light, and enters the spectrum measurement module 2 along the optical fiber light path 3 to achieve multi-channel photoluminescence spectrum detection.

[0039] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above 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.

[0040] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wafer photoluminescence multi-point detection device, characterized in that: include: A carrier (6) for carrying a sample to be tested (7); a light source module (1) for emitting monochromatic light to illuminate the surface of the sample to be tested (7) along a first light path; a spectrum measurement module (2), an optical fiber probe (5), an optical fiber light path (3), and a tube lens (10) arranged along a second light path; wherein the optical fiber light path (3) connects the optical fiber probe (5) and the spectrum measurement module (2); the optical fiber probe (5) is an array structure, and the spectrum measurement module (2) can realize multi-channel spectrum detection; the tube lens (10) comprises at least an objective lens (8) arranged on a side close to the sample to be tested (7); The optical fiber probe (5) is used to receive fluorescence emitted by multiple points on the surface of the sample (7) to be tested after being excited by the monochromatic light and transmitted along the second optical path; the tube lens (10) is used to image the fluorescence at the optical fiber probe (5); and the spectrum measurement module (2) is used to receive the fluorescence received by the optical fiber probe (5) and transmitted along the optical fiber optical path (3), and to simultaneously perform photoluminescence spectrum detection on multiple points on the surface of the sample (7) to be tested.

2. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: The spectrum measurement module (2) is a multi-channel spectrometer, or a plurality of single-channel spectrometers, or a plurality of single-channel spectrometers and a multi-channel spectrometer in common.

3. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: A first displacement module controls the optical fiber probes (5) so that all the optical fiber probes (5) are located at the image plane of the tube mirror (10).

4. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: The first displacement module controls the optical fiber probe (5) to move a first displacement along the optical axis direction of the tube lens (10).

5. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: The spectral measurement module (2) is a first spectral measurement module (21) and a second spectral measurement module (22), the optical fiber optical path (3) comprises a first optical fiber optical path (31) and a second optical fiber optical path (32), and the optical fiber probe (5) comprises a corresponding first optical fiber probe (51) and a second optical fiber probe (52); It also comprises a first light splitting module (41) disposed inside the tube lens (10); the fluorescence travels along the second light path, is split by the first light splitting module (41), and then enters the first spectrum measurement module (21) and the second spectrum measurement module (22) respectively through the first optical fiber light path (31) and the second optical fiber light path (32).

6. The wafer photoluminescence multi-point detection device according to claim 5, characterized in that: Also includes: The second displacement module controls the relative position of the first optical fiber probe (51) and the second optical fiber probe (52) so that the first optical fiber probe (51) and the second optical fiber probe (52) are offset by a second displacement on the image plane of the tube mirror (10).

7. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: A second light splitting module (42) is arranged inside the tube lens (10); After the monochromatic light enters the tube lens (10), it follows the first optical path, passes through the second light splitting module (42) and the objective lens (8), and then irradiates the surface of the sample to be tested (7); after the fluorescence enters the tube lens (10) through the objective lens (8), it passes through the second light splitting module (42), and then forms an image at the optical fiber probe (5).

8. The wafer photoluminescence multi-point detection device according to claim 1, characterized in that: Also includes: Camera module (9); Used to receive imaging light from the surface of the sample to be tested (7), and to take photos and perform 3D measurements on the surface of the sample to be tested (7).

9. The wafer photoluminescence multi-point detection device according to claim 8, characterized in that: Also includes: A third light splitting module (43) is arranged inside the tube lens (10); The camera module (9), the third light splitting module (43) and the objective lens (8) are arranged in sequence along a third optical path, and are used to receive imaging light of the surface of the sample to be tested (7) transmitted along the third optical path, and to take photos and perform 3D measurements on the surface of the sample to be tested (7); the third optical path is partially coaxial with the second optical path; and the third light splitting module (43) is used to separate the third optical path from the second optical path.

10. A wafer photoluminescence multi-point detection method, characterized in that: The wafer photoluminescence multi-point detection device as claimed in any one of claims 1 to 9 comprises: The light source module (1) emits monochromatic light to illuminate the surface of the sample to be tested (7) along a first light path; Adjusting the position of the optical fiber probe (5) so that the optical fiber probe (5) is located at a predetermined position; The optical fiber probe (5) receives the excitation light generated by the sample to be tested (7) after receiving the monochromatic light, and enters the spectrum measurement module (2) along the optical fiber light path (3), thereby realizing multi-channel photoluminescence spectrum detection.

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