Bimodal semiconductor material detection system and method based on optical path multiplexing

Abstract

The invention discloses a bimodal semiconductor material detection system and method based on optical path multiplexing. The technical problem that an existing technology for detecting an object to be detected through combination of OCT and fluorescence spectrum can only be used under a single condition is solved. The system comprises an OCT imaging unit, a fluorescence imaging unit and a data processing unit, the OCT imaging unit comprises a broadband light source, an OCT spectrograph, an optical fiber coupler, a first collimator, a reference arm, a first band-pass optical filter, a spectroscope, a sample arm and a dynamic focusing lens. The fluorescence imaging unit comprises a fluorescence spectrometer, a No.2 band-pass optical filter, a fluorescence light source, a second collimator and an excitation optical filter; and the data processing unit is used for converting a received signal of the OCT spectrograph into an OCT image and simultaneously converting a received signal of the fluorescence spectrograph into a fluorescence spectrum for analyzing the structure and composition of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material detection, and in particular relates to a dual-mode semiconductor material detection system and method based on optical path multiplexing. Background Art

[0002] Optical coherence tomography (OCT) is based on the principle of low-coherence interference and can obtain micron-level structural information of semiconductor materials in a non-contact manner. However, its imaging mechanism relies on differences in the refractive index of the materials and cannot analyze the physical nature of chemical composition and microscopic defects. Taking the inspection of gallium nitride (GaN) epitaxial wafers as an example, although OCT can capture the morphology of the interlayer interface, it cannot distinguish between microcracks caused by stress and lattice distortion caused by carbon contamination. It is also limited by axial resolution and lacks sensitivity to sub-surface nanoscale defects, with a missed detection rate of over 15%. In addition, in industrial workshop environments, phase noise will significantly reduce the signal-to-noise ratio of low-reflectivity materials, making it difficult to meet the reliability requirements of online detection.

[0003] Fluorescence spectroscopy can analyze the composition and lattice state by detecting bandgap luminescence or stress-induced peak shifts in materials. However, the spatial resolution of its wide-field imaging mode is >10μm, which cannot accurately match the micron-level structural data of OCT, resulting in inaccurate defect coordinate positioning. Ultraviolet excitation light in high-refractive index materials causes signal attenuation of more than 70% due to total reflection loss, and the anti-reflection coating commonly used in semiconductor processes emits parasitic fluorescence in the 450-600nm band, resulting in false positive signals. Traditional fluorescence detection relies on long integration times, usually >100ms for a single point, and endogenous luminescence. A full inspection of a single 300mm wafer takes more than 10 hours, and it is impossible to actively mark interface impurities during epitaxial growth. The sensitivity of component detection is limited to above 0.1at%.

[0004] OCT and fluorescence spectroscopy are theoretically complementary in structure-composition detection. Existing research has begun to use a combination of OCT and fluorescence spectroscopy to detect objects. The Chinese invention patent application "OCT and Fluorescence Composite Microendoscopic Imaging System", publication number: CN 113180598 A, discloses an OCT and fluorescence composite microendoscopic imaging system, including: an OCT module, a fluorescence microscopy module, a shared microprobe, and an image processing device. The microprobe effectively combines and separates the optical paths of the OCT module and the fluorescence microscopy module, allowing the two light paths to be focused on the same focal plane. OCT imaging and fluorescence imaging can be performed simultaneously on the same area of the sample, thereby obtaining more comprehensive sample information. However, this application still has the disadvantages that OCT and fluorescence may have optical path differences due to optical path differences, and can only be used in a single situation, such as endoscopic imaging, and cannot be adapted to multiple detection situations. Summary of the Invention

[0005] In order to solve the defect that the existing technology of combining OCT and fluorescence spectroscopy to detect objects to be detected can only be used in a single situation and cannot be adapted to multiple detection situations, the present invention provides a dual-modal semiconductor material detection system based on optical path multiplexing, which includes an OCT imaging unit, a fluorescence imaging unit and a data processing unit; the OCT imaging unit includes a broadband light source, an OCT spectrometer, a fiber coupler, a first collimator, a reference arm, a bandpass filter No. 1, a spectroscope, a sample arm and a dynamic focusing lens; the fluorescence imaging unit includes a fluorescence spectrometer, a bandpass filter No. 2, a fluorescence light source, a second collimator and an excitation filter; the data processing unit converts the signal received from the OCT spectrometer into an OCT image, and simultaneously converts the signal received from the fluorescence spectrometer into a fluorescence spectrum for analyzing the structure and composition of the material.

[0006] Furthermore, the sample arm includes a binocular mirror and a synchronous scanning galvanometer.

[0007] Furthermore, in the OCT imaging unit, the broadband light emitted by the broadband light source is split into reference light and sample light through the fiber coupler and the first collimator. The reference light is emitted to the reference arm, and the sample light is emitted to the sample arm; the sample arm emits the received sample light to the dynamic focusing lens for optical path integration with the fluorescence excitation light, and then emits it to the material detection area.

[0008] Furthermore, in the fluorescence imaging unit, the fluorescence excitation light emitted by the fluorescence light source passes through a second collimator, and then passes through an excitation filter to filter out stray light before being emitted to the sample arm; the sample arm emits the received fluorescence excitation light to the dynamic focusing lens for optical path integration with the sample light, and then obtains the integrated light and emits it to the material detection area.

[0009] Furthermore, after the integrated light is emitted into the material detection area, it is reflected by the material to be detected, passes through the dynamic focusing lens and the sample arm, and then enters the spectrometer, which separates the integrated light into sample light and fluorescence excitation light. The sample light is filtered by bandpass filter No. 1 and then returns to the OCT spectrometer along the original light path. The fluorescence excitation light is reflected by the spectrometer and filtered by bandpass filter No. 2 before entering the fluorescence spectrometer, allowing simultaneous detection of the same area of the material.

[0010] Furthermore, in the sample arm, the binomial mirror transmits the broadband light emitted by the broadband light source and the integrated light reflected by the material detection area, and reflects the fluorescence excitation light emitted by the fluorescence light source, thereby realizing dual-band optical path separation and multiplexing; the synchronous scanning galvanometer adopts a dual-axis magnetic levitation drive to control the light beam deflection and ensure spatial synchronization between the broadband light and the fluorescence excitation light.

[0011] Furthermore, the No. 2 bandpass filter and the excitation filter use a filter wheel, and the filter wheel integrates several bandpass filters.

[0012] The present invention also provides a dual-mode semiconductor material detection method based on optical path multiplexing, which is based on the above system and specifically comprises: At the beginning of the test, the material to be tested is placed in the material testing area. The filter types selected in the filter wheel of the No. 2 bandpass filter and the excitation filter are adjusted according to the specific material to be tested. The broadband light source and the fluorescence light source start working at the same time. The broadband light emitted by the broadband light source is split into reference light and sample light through the fiber coupler and the first collimator. The reference light is emitted to the reference arm, and the sample light is emitted to the sample arm. The fluorescence excitation light emitted by the fluorescence light source passes through the second collimator, and then passes through the excitation filter to filter out stray light before being emitted to the sample arm; the sample arm transmits the received fluorescence excitation light to the dynamic focusing lens for optical path integration with the sample light, and then obtains the integrated light and emits it to the material detection area; The material to be tested reflects the integrated light, passes through the dynamic focusing lens and the sample arm, and then enters the spectrometer, which divides the integrated light into sample light and fluorescence excitation light. The sample light is filtered by bandpass filter No. 1 and returns to the OCT spectrometer along the original light path. The fluorescence excitation light is reflected by the spectrometer and filtered by bandpass filter No. 2 before entering the fluorescence spectrometer to simultaneously test the same area of the material.

[0013] The beneficial effects of the present invention are: In the prior art, in OCT and fluorescence composite detection systems, a design structure is adopted in which the fluorescence emission light path and the fluorescence receiving light path share a common light path in the fluorescence light path. Although such a design can save space, it also limits the application scope of the detection system. In the present invention, the fluorescence emission light path and the fluorescence receiving light path are completely separated into two parts, and then filter wheels are integrated and used in the two light paths respectively. The filter wheels integrate several bandpass filters, so that the filters used in the filter wheels can be adjusted according to different detection needs, thereby adapting to various detection requirements; and the present invention can achieve a single-point detection time of less than 10ms through the coordinated control of the dynamic focusing lens and the filter wheel, greatly improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 2 is a structural diagram of a dual-mode semiconductor material detection system based on optical path multiplexing in an embodiment of the present invention; Figure 2 This is a diagram of the internal structure of the sample arm in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0016] Example 1 This embodiment provides a dual-mode semiconductor material detection system based on optical path multiplexing, such as Figure 1 As shown, the system includes an OCT imaging unit 17, a fluorescence imaging unit 15 and a data processing unit 16; the OCT imaging unit 17 includes a broadband light source 1, an OCT spectrometer 2, a fiber coupler 3, a first collimator 4, a reference arm 5, a bandpass filter No. 1 6, a spectroscope 7, a sample arm 8 and a dynamic focusing lens 9; the fluorescence imaging unit 15 includes a fluorescence spectrometer 10, a bandpass filter No. 2 11, a fluorescence light source 12, a second collimator 13 and an excitation filter 14; the data processing unit 16 converts the signal received from the OCT spectrometer 2 into an OCT image, and converts the signal received from the fluorescence spectrometer 10 into a fluorescence spectrum for analyzing the structure and composition of the material.

[0017] like Figure 2 The figure shows the internal structure of the sample arm 8 , which includes a binocular mirror 19 and a synchronous scanning galvanometer 21 .

[0018] Example 2 This embodiment is a further limitation of Embodiment 1. In the OCT imaging unit 17, the broadband light emitted by the broadband light source 1 is split into reference light and sample light through the fiber coupler 3 and the first collimator 4. The reference light is emitted to the reference arm 5, and the sample light is emitted to the sample arm 8. The sample arm 8 emits the received sample light to the dynamic focusing lens 9 for optical path integration with the fluorescence excitation light, and then emits it to the material detection area 24.

[0019] In the fluorescence imaging unit 15 , the fluorescence excitation light emitted by the fluorescence light source 12 passes through the second collimator 13 , and then passes through the excitation filter 14 to filter out stray light before being emitted to the sample arm 8 ; the sample arm 8 emits the received fluorescence excitation light to the dynamic focusing lens 9 , and after optical path integration with the sample light, the obtained integrated light is emitted to the material detection area 24 .

[0020] After the integrated light is emitted to the material detection area 24, the material to be detected reflects the integrated light, passes through the dynamic focusing lens 9 and the sample arm 8, and then enters the spectrometer 7, which separates the integrated light into sample light and fluorescence excitation light. The sample light is filtered by the bandpass filter No. 1 and returns to the OCT spectrometer 2 along the original light path. The fluorescence excitation light is reflected by the spectrometer 7 and filtered by the bandpass filter No. 2 11 before entering the fluorescence spectrometer 10, and the same area of the material is detected simultaneously.

[0021] In the sample arm 8, the binomial mirror 19 transmits the broadband light emitted by the broadband light source 1 and the integrated light reflected by the material detection area 24, and reflects the fluorescence excitation light emitted by the fluorescence light source 12, thereby realizing dual-band optical path separation and multiplexing; the synchronous scanning galvanometer 21 adopts a dual-axis magnetic levitation drive to control the light beam deflection and ensure spatial synchronization between the broadband light and the fluorescence excitation light.

[0022] The No. 2 bandpass filter 11 and the excitation filter 14 use a filter wheel, and the filter wheel integrates several bandpass filters.

[0023] Example 3 This embodiment is a further limitation of Example 1. The binomial mirror 19 uses a wide-band binomial mirror to achieve a reflection band covering common excitation wavelengths such as 266nm, 325nm, 532nm, and 785nm, and a transmission band covering the fluorescence emission range such as 400-900nm and OCT broadband light 1300nm, achieving a reflectivity of >95% and a transmittance of >90%.

[0024] The spectroscope 7 uses a wide-band spectroscope to achieve a reflection band covering the fluorescence emission range, such as 400-900 nm, and transmit OCT broadband light of 1300 nm, achieving a reflectivity > 95% and a transmittance > 90%.

[0025] The bandpass filter 6 has a central wavelength of 1300 nm and a bandwidth of ±50 nm, transmits 1300 nm OCT signals and blocks other wavelengths.

[0026] The No. 2 bandpass filter 11 uses a filter wheel, which integrates multiple bandpass filters such as 630nm, 550nm, and 720nm, and can adjust bandpass filters of multiple different bands.

[0027] The excitation filter 14 uses a filter wheel, which integrates multiple bandpass filters such as 325nm and 532nm, and can adjust bandpass filters of multiple different bands.

[0028] In summary, different semiconductor materials can be detected by replacing the fluorescence excitation light source and filter. For example, the detection of Si material can use a 325nm fluorescence light source 12, a 320-340nm bandpass filter as an excitation filter 14, and a 630nm bandpass filter No. 2 11.

[0029] The present invention provides an OCT-fluorescence dual-modal semiconductor material detection system and method based on optical path multiplexing. The light beam provided by a broadband light source and the light beam provided by a fluorescence excitation light source can be simultaneously emitted into the material detection area through a common optical path, and the light reflected from the broadband light source and the fluorescence emitted by the material are simultaneously collected and converted into an OCT image and a fluorescence spectrum. The fluorescence spectrum and the OCT image are combined to obtain the nanoscale structural deformation and composition characteristics of the material detection area.

Claims

1. A dual-mode semiconductor material detection system based on optical path multiplexing, characterized in that: The system includes an OCT imaging unit (17), a fluorescence imaging unit (15) and a data processing unit (16); the OCT imaging unit (17) includes a broadband light source (1), an OCT spectrometer (2), a fiber coupler (3), a first collimator (4), a reference arm (5), a bandpass filter No. 1 (6), a spectroscope (7), a sample arm (8) and a dynamic focusing lens (9); the fluorescence imaging unit (15) includes a fluorescence spectrometer (10), a bandpass filter No. 2 (11), a fluorescence light source (12), a second collimator (13) and an excitation filter (14); the data processing unit (16) converts the signal received from the OCT spectrometer (2) into an OCT image, and converts the signal received from the fluorescence spectrometer (10) into a fluorescence spectrum for analyzing the structure and composition of the material.

2. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 1, characterized in that: The sample arm (8) includes a binocular mirror (19) and a synchronous scanning galvanometer (21).

3. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 2, characterized in that: In the OCT imaging unit (17), the broadband light emitted by the broadband light source (1) is split into reference light and sample light through the fiber coupler (3) and the first collimator (4). The reference light is emitted to the reference arm (5), and the sample light is emitted to the sample arm (8). The sample arm (8) emits the received sample light to the dynamic focusing lens (9), which integrates the light path with the fluorescence excitation light and then emits it to the material detection area (24).

4. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 3, characterized in that: In the fluorescence imaging unit (15), the fluorescence excitation light emitted by the fluorescence light source (12) passes through the second collimator (13), and then passes through the excitation filter (14) to filter out stray light before being emitted to the sample arm (8); the sample arm (8) emits the received fluorescence excitation light to the dynamic focusing lens (9), which integrates the light path with the sample light to obtain the integrated light and emits it to the material detection area (24).

5. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 4, characterized in that: After the integrated light is emitted to the material detection area (24), the material to be detected reflects the integrated light, passes through the dynamic focusing lens (9) and the sample arm (8), and then enters the spectrometer (7), which divides the integrated light into sample light and fluorescence excitation light. The sample light is filtered by the No. 1 bandpass filter (6) and then returns to the OCT spectrometer (2) along the original light path. The fluorescence excitation light is reflected by the spectrometer (7) and filtered by the No. 2 bandpass filter (11) and then enters the fluorescence spectrometer (10), so that the same area of the material is detected simultaneously.

6. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 5, characterized in that: In the sample arm (8), the binocular mirror (19) transmits the broadband light emitted by the broadband light source (1) and the integrated light reflected by the material detection area (24), and reflects the fluorescence excitation light emitted by the fluorescence light source (12), thereby realizing dual-band optical path separation and multiplexing; the synchronous scanning galvanometer (21) adopts a dual-axis magnetic levitation drive to control the beam deflection and ensure spatial synchronization between the broadband light and the fluorescence excitation light.

7. The dual-mode semiconductor material detection system based on optical path multiplexing according to claim 6, characterized in that: The No. 2 bandpass filter (11) and the excitation filter (14) use a filter wheel, and the filter wheel integrates several bandpass filters.

8. A dual-mode semiconductor material detection method based on optical path multiplexing, the method being performed using the system according to claim 7, characterized in that: The method is specifically as follows: When the test begins, the material to be tested is placed in the material testing area (24), the types of filters selected in the filter wheel of the No. 2 bandpass filter (11) and the excitation filter (14) are adjusted according to the specific material to be tested, and the broadband light source (1) and the fluorescent light source (12) start working at the same time; The broadband light emitted by the broadband light source (1) is split into reference light and sample light through the fiber coupler (3) and the first collimator (4), the reference light is emitted to the reference arm (5), and the sample light is emitted to the sample arm (8); The fluorescent excitation light emitted by the fluorescent light source (12) passes through the second collimator (13), and then passes through the excitation filter (14) to filter out stray light before being emitted to the sample arm (8); the sample arm (8) emits the received fluorescent excitation light to the dynamic focusing lens (9), which integrates the light path with the sample light to obtain the integrated light and emits it to the material detection area (24); The material to be tested reflects the integrated light, which passes through the dynamic focusing lens (9) and the sample arm (8) and then enters the spectrometer (7), where the integrated light is divided into sample light and fluorescence excitation light. The sample light is filtered by the bandpass filter No. 1 (6) and then returns to the OCT spectrometer (2) along the original light path. The fluorescence excitation light is reflected by the spectrometer (7) and filtered by the bandpass filter No. 2 (11) and then enters the fluorescence spectrometer (10), whereby the same area of the material is tested simultaneously.

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