Semiconductor structure doping concentration distribution measurement system

Abstract

The application relates to the technical field of optical measurement, and discloses a semiconductor structure doping concentration distribution measuring system, which comprises an excitation module for generating excitation light; a light splitting module located on the light path of the excitation light and used for splitting the excitation light into first power light and second power light, wherein the first power light is used for irradiating a sample to be measured; a measuring module located on the light path of the second power light and used for measuring the power of the second power light; and a collecting module used for collecting the spectrum signal of test light generated by the sample to be measured under the excitation of the first power light. The embodiment of the application can realize non-contact and nondestructive measurement of the doping concentration distribution of a semiconductor structure.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and more specifically to a semiconductor structure doping concentration distribution measurement system. Background Technology

[0002] Semiconductor structures have a diffusion layer, which is an important component and crucial for forming pn junctions and separating free electrons and holes. The characteristics of the diffusion layer are usually characterized by the doping concentration distribution of the semiconductor structure.

[0003] In related technologies, methods for measuring the doping concentration distribution of semiconductor structures typically include electrochemical capacitance-voltage profiler (ECV), secondary ion mass spectrometry (SIMS), and spreading resistance profile (SRP). However, these measurement methods are tactile and destructive, and therefore have limitations. Summary of the Invention

[0004] In view of this, the present invention provides a semiconductor structure doping concentration distribution measurement system to solve the problems of contact and destructiveness in semiconductor structure doping concentration distribution measurement.

[0005] This invention provides a semiconductor structure doping concentration distribution measurement system, comprising: an excitation module for generating excitation light; a beam splitting module located in the optical path of the excitation light for splitting the excitation light into a first power light and a second power light, wherein the first power light is used to irradiate a sample under test; a measurement module located in the optical path of the second power light for measuring the power of the second power light; and an acquisition module for acquiring the spectral signal of the test light generated by the sample under test under the excitation of the first power light.

[0006] Beneficial effects: The measurement system can be calibrated using a calibration sample with a known doping concentration distribution, and then the doping concentration distribution of the sample to be tested can be measured. At this time, different samples to be tested can be measured without changing the measurement system. The measurement system has high applicability, is convenient and fast, has a short measurement time, and high measurement accuracy. In addition, the measurement method of the measurement system is non-contact and non-destructive, which reduces the probability of damage to the sample to be tested.

[0007] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes a dichroic mirror located in the optical path of the test light, the test light being refracted by the dichroic mirror to the acquisition module.

[0008] Beneficial effects: It can filter out stray light in the test light, avoid interference from stray light in the measurement results, and improve the accuracy of the measured structure.

[0009] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes: a neutral density filter located in the optical path of the test light and between the dichroic mirror and the acquisition module; and a first focusing lens located in the optical path of the test light and between the dichroic mirror and the neutral density filter.

[0010] Beneficial effects: It can attenuate the intensity of the test light without changing the spectral energy distribution of the test light, so as to prevent damage to the acquisition module or inaccurate data acquisition caused by excessive light. In addition, the first focusing lens can focus the test light to reduce the light spot incident on the acquisition module and improve the reliability of data acquisition.

[0011] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes: a first objective lens located in the optical path of the first power light and the optical path of the excitation light; a dichroic mirror located between the first objective lens and the first objective lens; the first power light irradiates the sample to be tested after passing through the first objective lens; and the excitation light is directed to the dichroic mirror after passing through the first objective lens.

[0012] Beneficial effects: It can focus the first power light, reduce the size of the light spot incident on the sample, and improve the accuracy of the excited area of ​​the sample.

[0013] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes: a carrier module having a through hole and a carrier surface, the carrier surface being movable relative to the through hole and used to carry the sample to be tested, the first power light passing through the through hole; and a position control module connected to the carrier module, the position control module controlling the displacement of the carrier surface relative to the through hole.

[0014] Beneficial effects: It enables minute movements of the sample to be tested, resulting in more precise measurement of the sample's position and high measurement accuracy.

[0015] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes: an imaging light source for generating imaging light, the imaging light for illuminating the region of the sample under test that is excited by the first power light; a reflector module, the imaging light being reflected by the sample under test to the reflector module; and an imaging module, the imaging light being reflected by the reflector module to the imaging module.

[0016] Beneficial effects: It can obtain the current detection area of ​​the sample in a timely manner, thereby adjusting the position of the sample according to the test requirements and ensuring that the current detection area meets the test requirements, thus improving the detection accuracy.

[0017] In one optional embodiment, the system further includes a second objective lens, which is located in the optical path of the imaging light and between the reflecting module and the imaging module.

[0018] Beneficial effect: Focusing the imaging light reduces the size of the light spot incident on the imaging module, thereby improving spatial resolution.

[0019] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes a processing module, wherein the acquisition module, the position control module, and the imaging module are all connected to the processing module, and the processing module is used to process the spectral signal of the test light.

[0020] Beneficial effects: The linkage efficiency between the acquisition module, position control module and imaging module is higher, which is conducive to improving test accuracy.

[0021] In one optional embodiment, the semiconductor structure doping concentration distribution measurement system further includes: a second focusing lens located in the optical path of the second power light and between the beam splitting module and the measurement module; and / or a beam expander group located in the optical path of the excitation light and between the excitation module and the beam splitting module; and / or a collimator located in the optical path of the excitation light and between the excitation module and the beam splitting module.

[0022] Beneficial effects: It ensures the collimation of the excitation light and focuses the second power light onto the measurement module, thereby improving the accuracy of the measurement.

[0023] In one alternative implementation, the power of the first power light is greater than the power of the second power light.

[0024] Beneficial effects: Improves the excitation effect on the sample under test and reduces the cost of the measurement module. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1This is a schematic diagram of the measurement system according to an embodiment of the present invention;

[0027] Figure 2 This is the spectrum of the sample under test in the excited state.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Measurement system; 2. Sample to be tested;

[0030] 100. Excitation module; 101. Optical fiber; 110. Beam expander assembly; 120. Collimator;

[0031] 200. Beam-splitting module; 210. First objective lens;

[0032] 300. Measurement module; 310. Second focusing lens;

[0033] 400. Acquisition module; 410. Dichroic mirror; 420. Neutral density filter; 430. First focusing lens; 440. Acquisition card;

[0034] 500, load-bearing module; 510, through hole; 520, load-bearing surface;

[0035] 600. Position control module;

[0036] 700. Imaging light source; 710. Reflection module; 720. Imaging module; 730. Second objective lens;

[0037] 800, Processing Module. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] In the description of this invention, "a plurality of" means two or more. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] Photoluminescence (PL) spectroscopy is a non-contact and non-destructive characterization tool used to evaluate the fundamental properties of semiconductor structures. PL spectra are related to factors such as sample temperature, doping concentration distribution, interband absorption, and radiative recombination; changes in any of these parameters will affect the intensity and shape of the PL spectrum. Therefore, theoretically, changes in the PL spectrum can be used to qualitatively characterize the doping concentration distribution of the diffusion layer.

[0043] Photoluminescence technology uses laser light to irradiate the surface of a semiconductor structure, causing charge carriers in silicon to enter a higher-energy excited state. Subsequently, within a very short time, the charge carriers return from the excited state to the ground state, releasing energy as photons. Depending on the characteristics of the diffusion layer, the frequency and intensity of the photons emitted by the silicon material vary. Therefore, the doping concentration distribution of the diffusion layer can be further studied by analyzing its photoluminescence (PL) spectrum.

[0044] Laser irradiation of the semiconductor structure surface excites the silicon substrate and diffusion layer to generate different photons. At low temperatures, such as... Figure 2 As shown in region (a), the PL spectrum includes three distinct components: the band-to-band emission (Si BB) peak corresponding to λ1, the heavily doped band-to-band emission (HDBB) peak corresponding to λ2, and the zone-center optical photon replica (PR of HDBB) peak corresponding to λ3. Due to the bandgap narrowing effect of the diffusion layer, the HDBB peak has lower energy (i.e., longer wavelength). Furthermore, due to the band filling and band tailing effects in heavily doped silicon, the HDBB peak is significantly broader than the Si BB peak.

[0045] At room temperature, such as Figure 2As shown in the curve of region (b), due to the thermal broadening effect, the HDBB spectral peak and the SiBB spectral peak are difficult to distinguish and merge into a very broad spectral peak. Due to the presence of the HDBB spectral peak, the emission spectrum of the diffused layer still differs significantly from that of the silicon substrate at long wavelengths (wherein...). Figure 2 In region (b), the black solid line represents the spectral curve with a diffusion layer, and the red dashed line represents the spectral curve without a diffusion layer. Therefore, even at room temperature, this spectral characteristic can be used to study the doping concentration distribution of the diffusion layer.

[0046] The doping concentration distribution of a standard high-temperature diffused semiconductor structure follows a Gaussian distribution, as shown in the following formula:

[0047]

[0048] Where, N p For peak concentration, z p z represents the depth at which the peak concentration is located. f z is the depth factor. f and z p There is an inherent correlation in the standard high-temperature diffusion process: the deeper the peak concentration is located, the deeper the dopant atoms diffuse into the silicon substrate. If photoluminescence spectroscopy is used to characterize the diffusion layer, the PL spectrum needs to be converted to the parameter set {N}. p ,z p ,z f To reconstruct the doping concentration distribution.

[0049] Based on the above principles, a numerical model of PL spectrum and doping concentration distribution is established:

[0050] I1 is defined as the integral intensity between the wavelength λ1 of the Si BB spectral peak and the wavelength λ2 of the HDBB spectral peak (dominated by the silicon substrate), and I2 is defined as the integral intensity between the wavelength λ2 of the HDBB spectral peak and the wavelength λ3 of the PR of the HDBB spectral peak (dominated by the diffusion layer). The integral intensity ratio R = I2 / I1 is used to quantitatively characterize the diffusion layer.

[0051] Under laser conditions with wavelength λexc1, the integral intensity ratio R1 and N are obtained. p ×(z p +z f The functional relationship of ) is used to obtain the integral intensity ratio R2 under a laser stripe with a wavelength of λexc2, and the relative change of the integral intensity ratio (R1-R2) / R1 and z are obtained. f The functional relationship is obtained by solving for the parameter N using two functions. p z p z f Finally, the doping concentration distribution of the diffusion layer is reconstructed using the above formula.

[0052] The following is combined Figures 1 to 2 The following describes embodiments of the present invention.

[0053] According to an embodiment of the present invention, a semiconductor structure doping concentration distribution measurement system 1 is provided. The measurement system 1 includes an excitation module 100, a spectrometer module 200, a measurement module 300, and a data acquisition module 400.

[0054] The excitation module 100 is used to generate excitation light. The beam splitting module 200 is located in the optical path of the excitation light and is used to split the excitation light into a first power light and a second power light. The first power light is used to irradiate the sample 2 under test. The measurement module 300 is located in the optical path of the second power light and is used to measure the power of the second power light. The acquisition module 400 is used to acquire the spectral signal of the test light generated by the sample 2 under the excitation of the first power light.

[0055] It should be noted that the sample under test 2 has a semiconductor structure, and can be a crystalline silicon solar cell. The excitation module 100 can include a wavelength-tunable laser. When the laser is a fiber laser, the excitation module 100 also includes a single-mode fiber 101. The laser beam propagates along the single-mode fiber 101, which has a beam-shaping function to improve the beam quality of the excitation light. The acquisition module 400 can be a detector, such as a spectrometer or spectral detector. The acquisition module 400 can be connected to an acquisition card 440 for collecting spectral signals. The beam splitting module 200 can be a beam splitter or other device with beam splitting capabilities.

[0056] By setting the excitation module 100, excitation light can be generated to excite the sample 2 under test. The sample 2 under test generates test light in the excited state. The test light is directed to the acquisition module 400. The acquisition module 400 acquires the spectral signal of the test light, thereby determining the doping concentration distribution of the sample 2 under test.

[0057] Specifically, before testing sample 2, a known doping concentration distribution (i.e., a known N) is placed in measurement system 1. p z p z f , and z p and z f The calibration sample (related to the relationship) is excited by excitation light emitted by excitation module 100, causing the calibration sample to generate a spectral signal in the excited state, and the integral intensity ratio R1 and N are obtained. p ×(z p +z f The first functional relationship of ), and (R1-R2) / R1 and z fThe second functional relationship can be obtained, and then different regions of the same standard sample can be excited, or multiple standard samples with different doping concentration distributions can be excited to obtain multiple first functional relationships and multiple second functional relationships, and a standard curve can be fitted.

[0058] After obtaining the above standard curve, the sample 2 to be tested is excited using excitation light of the above wavelength, and the integrated intensity ratios R1 and R2 of the sample 2 to be tested are obtained. The N of the sample 2 to be tested is then obtained using the above standard curve. p z p z f Then, by combining the above Gaussian distribution formula, the doping concentration distribution of the sample 2 to be tested is obtained.

[0059] Since the beam splitting capability of the beam splitting module 200 is fixed, the ratio of the power of the first power light to the power of the second power light is fixed. By setting the measurement module 300, the power of the second power light can be measured in real time, thereby confirming the power of the first power light. This achieves the function of monitoring the power of the first power light incident on the sample 2 under test, ensuring that the power of the laser incident on the surface of the sample 2 under test is the same each time, and improving the accuracy of the test.

[0060] In this way, after the measurement system 1 is calibrated using a calibration sample with a known doping concentration distribution, it can measure the doping concentration distribution of the sample to be tested 2. At this time, different samples to be tested 2 can be measured without changing the measurement system 1. The measurement system 1 has high applicability, is convenient and fast, has a short measurement time, and high measurement accuracy. In addition, the measurement method of the measurement system 1 is non-contact and non-destructive, which reduces the probability of damage to the sample to be tested 2.

[0061] like Figure 1 As shown, in this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a dichroic mirror 410. The dichroic mirror 410 is located in the optical path of the test light, and the test light is refracted by the dichroic mirror 410 to the acquisition module 400. By setting the dichroic mirror 410, stray light in the test light can be filtered out, avoiding interference from stray light in the measurement results and improving the accuracy of the measured structure.

[0062] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a neutral density filter 420 and a first focusing lens 430. The neutral density filter 420 is located in the optical path of the test light and is located between the dichroic mirror 410 and the acquisition module 400. The first focusing lens 430 is located in the optical path of the test light and is located between the dichroic mirror 410 and the neutral density filter 420.

[0063] By setting a neutral density filter 420, the intensity of the test light can be attenuated without changing the spectral energy distribution of the test light. This prevents damage to the acquisition module 400 or inaccurate data acquisition caused by excessive light, which helps to ensure the reliability and service life of the acquisition module 400.

[0064] In addition, by setting the first focusing lens 430, the test light can be focused to reduce the light spot incident on the acquisition module 400, avoid the test light being outside the acquisition area of ​​the acquisition module 400, and improve the reliability of data acquisition.

[0065] like Figure 1 As shown, in this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a first objective lens 210. The first objective lens 210 is located in the optical path of the first power light and the optical path of the excitation light. After passing through the first objective lens 210, the first power light illuminates the sample 2 to be tested, and after passing through the first objective lens 210, the excitation light is directed towards the dichroic mirror 410. The dichroic mirror 410 is located between the beam splitting module 200 and the first objective lens 210.

[0066] By setting the first objective lens 210, the first power light can be focused, reducing the spot size incident on the sample 2 to improve the accuracy of the excited area of ​​the sample 2. In other words, by increasing at least one of the magnification and numerical aperture of the first objective lens 210, the spot size incident on the sample 2 can be reduced, thereby improving the accuracy of the excited area of ​​the sample 2 and improving the reliability of the measurement results of the measurement system 1.

[0067] In addition, the test light generated by the sample 2 in the excited state can be diffused through the first objective lens 210, making the light spot of the test light illuminating the dichroic mirror 410 larger, which is beneficial to improving the effect of the dichroic mirror 410 in filtering stray light.

[0068] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a carrier module 500 and a position control module 600. The carrier module 500 has a through hole 510 and a carrier surface 520. The carrier surface 520 is movable relative to the through hole 510. The carrier surface 520 is used to carry the sample 2 to be tested. The first power light passes through the through hole 510. The position control module 600 is connected to the carrier module 500 and controls the displacement of the carrier surface 520 relative to the through hole 510.

[0069] For example, the bearing module 500 can be a piezoelectric control platform, and the position control module 600 can be a piezoelectric processing module. The piezoelectric control platform can achieve micron-level displacement to improve the accuracy of the displacement of the sample 2 under test, thereby improving the accuracy of the region of the sample 2 under test excited by the first power light and the measurement accuracy of the measurement system 1.

[0070] By incorporating the carrier module 500 and the position control module 600, minute movements of the sample 2 under test can be achieved, resulting in more precise measurement of the sample 2's position and higher measurement accuracy. Furthermore, the first power light is directed towards different regions of the sample 2, acquiring spectral energy maps of different regions of the sample 2, thus expanding the measurement data and facilitating more accurate measurement results. Additionally, due to the through-hole 510, even if the sample 2 under test moves, it will not affect the irradiation of the first power light onto the sample 2, ensuring the normal operation of the measurement system 1.

[0071] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes an imaging light source 700, a reflector module 710, and an imaging module 720. The imaging light source 700 is used to generate imaging light, which is used to illuminate the area of ​​the sample 2 under test that is excited by the first power light. The imaging light is reflected by the sample 2 under test to the reflector module 710, and the imaging light is reflected by the reflector module 710 to the imaging module 720.

[0072] For example, the imaging light source 700 can be an LED light source, the reflector module 710 can be a semi-transparent plane mirror, and the imaging module 720 can be a camera, such as a charge-coupled device (CCD) camera or a CMOS (Complementary Metal-Oxide Semiconductor) camera. It is understandable that the imaging light source 700 can also be other types of light sources, the reflector module 710 can be other devices with reflective functions, and the imaging module 720 can be other image sensors.

[0073] By setting up the imaging light source 700, the reflective module 710, and the imaging module 720, the current detection area of ​​the sample 2 to be tested can be obtained in a timely manner. This allows the position of the sample 2 to be tested to be adjusted according to the test requirements, and ensures that the current detection area meets the test requirements, thereby improving the detection accuracy.

[0074] In addition, the reflective module 710 can be located between the imaging light source 700 and the sample 2 under test. The imaging light of the imaging light source 700 is perpendicular to the sample 2 under test. The angle between the reflective module 710 and the imaging light can be 45°. The image acquired by the imaging module 720 has better accuracy and less distortion, which is beneficial to improving the test accuracy.

[0075] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a second objective lens 730. The second objective lens 730 is located in the optical path of the imaging light and is located between the reflection module 710 and the imaging module 720. The imaging light is collected by the imaging module 720 after passing through the second objective lens 730.

[0076] By setting the second objective lens 730, the imaging light can be focused, reducing the spot size incident on the imaging module 720, thereby improving the spatial resolution. In other words, by increasing at least one of the magnification and numerical aperture of the second objective lens 730, the spot size incident on the imaging module 720 can be reduced, thereby improving the spatial resolution.

[0077] With the setup of the first objective lens 210, the carrier module 500, and the second objective lens 730, the detection area of ​​the sample 2 under test can reach the micrometer level, which can be used to detect diffusion areas of micrometer size and improve the measurement accuracy of the measurement system 1.

[0078] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a processing module 800. The acquisition module 400, the position control module 600 and the imaging module 720 are all connected to the processing module 800. The processing module 800 is used to process the spectral signal of the test light fed back by the acquisition module 400.

[0079] The processing module 800 may have a display screen or a touch screen, so that users can observe the position of the sample 2 under test, the status of the carrier module 500 and the data of the acquisition module 400 in real time through the processing module, thereby improving the timeliness of feedback.

[0080] By setting up the processing module 800, the position of the sample 2 under test can be adjusted in a timely manner according to the image status of the imaging module 720, through the position control module 600, so that the position of the sample 2 under test meets the test requirements. Furthermore, based on the data from the acquisition module 400 and the image status of the imaging module 720, the spectrum corresponding to the excitation state of different regions of the sample 2 under test can be obtained. Also, based on the data from the acquisition module 400, the position control module 600 can be used to control the position of the sample 2 under test to adjust the position of the sample 2 under test, thereby improving the test efficiency. The linkage efficiency between the acquisition module 400, the position control module 600, and the imaging module 720 is higher, which is conducive to improving the test accuracy.

[0081] like Figure 1As shown, in this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a collimator 120, which is located in the optical path of the excitation light. The excitation light passes through the collimator 120 and is directed towards the beam splitting module 200. The collimator 120 is located between the excitation module 100 and the beam splitting module 200. By setting the collimator 120, the collimation of the excitation light is ensured, thereby improving the accuracy and performance of the measurement system 1.

[0082] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a beam expander group 110. The beam expander group 110 is located in the optical path of the excitation light, and the excitation light is directed to the beam splitter module 200 through the beam expander group 110. Specifically, the beam expander group 110 is located between the excitation module 100 and the beam splitter module 200, and more specifically, it is located between the collimator 120 and the beam splitter module 200.

[0083] For example, the beam expander assembly 110 may include a first lens 111 and a second lens 112. The first lens 111 is closer to the excitation module than the second lens 112. That is to say, the excitation light first passes through the first lens 111, then through the second lens 112, and then is directed to the beam splitter module. The first lens 111 can focus the excitation light, and the second lens 112 can diverge the excitation light.

[0084] In this way, the beam expander group 110 can change the beam diameter and divergence angle of the excitation light, calibrate the excitation light after passing through the collimator 120, increase the beam diameter of the excitation light, so that the excitation light has a larger distribution area on the beam splitter module 200, and the beam splitter module 200 has a better beam splitting effect on the excitation light.

[0085] like Figure 1 As shown, in the technical solution of this embodiment, the semiconductor structure doping concentration distribution measurement system 1 further includes a second focusing lens 310. The second focusing lens 310 is located in the optical path of the second power light, and the second power light passes through the second focusing lens 310 and is directed towards the measurement module 300. The second focusing lens 310 is located between the beam splitting module 200 and the measurement module 300.

[0086] By setting the second focusing lens 310, the second power light can be focused, reducing the size of the light spot incident on the measurement module 300, thereby focusing the second power light onto the measurement part of the measurement module 300 and improving the accuracy of the measurement.

[0087] In the technical solution of this embodiment, the power of the first power light is greater than the power of the second power light. The ratio of the power of the first power light to the power of the second power light can be 6 to 9, for example, the ratio of the power of the first power light to the power of the second power light is 6, 7, 8 or 9.

[0088] In this way, the main part of the excitation light is used to excite the sample 2 under test, improving the excitation effect of the sample 2 under test, so as to ensure that the sample 2 under test can generate a reliable spectrum under the excitation of the first power light, thereby ensuring the acquisition accuracy of the acquisition module 400. In addition, since the power of the second power light is relatively small, the upper limit requirement for the power detection of the measurement module 300 is lower, which can reduce the cost of the measurement module 300 and thus reduce the cost of the measurement system 1.

[0089] It should be noted that when at least one of the numerical aperture of the first objective lens 210, the numerical aperture of the second objective lens 730, the excitation light energy, and the excitation light power is increased, the sensitivity of the PL spectrum to the measurement system 1 will be higher.

[0090] The following describes the measurement method using measurement system 1 to measure sample 2:

[0091] First, a calibration sample is placed in the carrier module 500. The doping concentration distribution of the calibration sample is known, i.e., the parameter N of the calibration sample. p z p z f , and z p and z f The relationship is known;

[0092] Then, the excitation module 100 is controlled to generate excitation light with wavelengths λexc1 and λexc2, respectively, to obtain R1 and N. p ×(z p +z f The first calibration curve, and (R1-R2) / R1 with z f The second calibration curve is obtained, and the corresponding functional relationship is fitted by the two calibration curves;

[0093] Next, the calibration sample is removed, and the sample to be tested 2 is placed in the carrier module 500. The excitation module 100 is controlled to generate excitation light with wavelengths λexc1 and λexc2 to obtain R1exp and R2exp of the sample to be tested 2. Using the first calibration curve, the second calibration curve, and z p and z f The functional relationship is used to obtain the parameter N of the sample to be tested 2. p z p z f .

[0094] Finally, based on the parameter N of sample 2 to be tested p z p z f , combined Reconstruct the doping concentration distribution curve of sample 2.

[0095] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system, characterized in that, include: Excitation module (100) is used to generate excitation light; A beam splitting module (200) is located in the optical path of the excitation light and is used to split the excitation light into a first power light and a second power light. The first power light is used to irradiate the sample to be tested (2). A measurement module (300) is located in the optical path of the second power light and is used to measure the power of the second power light; The acquisition module (400) is used to acquire the spectral signal of the test light generated by the sample to be tested (2) under the first power light excitation; A carrier module (500) is used to carry the sample to be tested (2); A position control module (600) is connected to the carrier module (500); The processing module (800) is connected to both the acquisition module (400) and the position control module (600). The processing module (800) is used to process the spectral signal of the test light. The method for measuring the doping concentration distribution of the semiconductor structure includes: First, a calibration sample is placed on the carrier module. The doping concentration distribution of the calibration sample is known, that is, the parameters Np, zp, and zf of the calibration sample, as well as the relationship between zp and zf, are known. Among them, Np is the peak concentration, zp is the depth at which the peak concentration is located, zf is the depth factor, and zf and zp have an intrinsic correlation in the standard high-temperature diffusion process. Then, the excitation module is controlled to generate excitation light with wavelengths λexc1 and λexc2. Under the laser condition of wavelength λexc1, the first calibration curve of integral intensity ratio R1 versus Np×(zp+zf) is obtained. Under the laser stripe of wavelength λexc2, the integral intensity ratio R2 is obtained, and the second calibration curve of the relative change of integral intensity ratio (R1-R2) / R1 versus zf is obtained. The corresponding functional relationship is fitted by the two calibration curves. I1 is defined as the integral intensity between the wavelength λ1 of the silicon substrate spectral peak and the wavelength λ2 of the heavily doped interband emission spectral peak of the diffusion layer. I2 is defined as the integral intensity between the wavelength λ2 of the heavily doped interband emission spectral peak of the diffusion layer and the wavelength λ3 of the photon replication spectral peak of the heavily doped interband emission spectral peak of the diffusion layer. The integral intensity ratio R=I2 / I1 is used to quantitatively characterize the diffusion layer. Next, remove the calibration sample, place the sample to be tested on the carrier module, control the excitation module to generate excitation light with wavelengths λexc1 and λexc2, and obtain R1exp and R2exp of the sample to be tested. Using the first calibration curve, the second calibration curve, and the functional relationship between zp and zf, the parameters Np, zp, and zf of the sample to be tested are obtained. Finally, based on the parameters Np, zp, and zf of the sample to be tested, combined with... Reconstruct the doping concentration distribution curve of the sample to be tested.

2. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 1, characterized in that, Also includes: A dichroic mirror (410) is located in the optical path of the test light, and the test light is refracted by the dichroic mirror (410) to the acquisition module (400).

3. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 2, characterized in that, Also includes: A neutral density filter (420) is located in the optical path of the test light and between the dichroic mirror (410) and the acquisition module (400). A first focusing lens (430) is located in the optical path of the test light and between the dichroic mirror (410) and the neutral density filter (420).

4. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 3, characterized in that, Also includes: The first objective lens (210) is located in the optical path of the first power light and the optical path of the excitation light. The dichroic mirror (410) is located between the first objective lens (210) and the beam splitter (200). The first power light illuminates the sample to be tested (2) after passing through the first objective lens (210), and the test light is directed to the dichroic mirror (410) after passing through the first objective lens (210).

5. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 1, characterized in that, The carrier module (500) has a through hole (510) and a carrier surface (520). The carrier surface (520) is movable relative to the through hole (510). The carrier surface (520) is used to carry the sample to be tested (2). The first power light passes through the through hole (510). The position control module (600) controls the displacement of the bearing surface (520) relative to the through hole (510).

6. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 5, characterized in that, Also includes: An imaging light source (700) is used to generate imaging light, which is used to illuminate the area of ​​the sample under test (2) that is excited by the first power light; A reflective module (710) is used to reflect the imaging light to the sample to be tested (2). Imaging module (720), the imaging light is reflected to the imaging module (720) by the reflector module (710).

7. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 6, characterized in that, Also includes: The second objective lens (730) is located in the optical path of the imaging light and between the reflector module (710) and the imaging module (720).

8. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to claim 6, characterized in that, The imaging module (720) is connected to the processing module (800).

9. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to any one of claims 1-8, characterized in that, Also includes: A second focusing lens (310) is located in the optical path of the second power light and between the beam splitting module (200) and the measurement module (300); and / or A beam expander assembly (110) is located in the optical path of the excitation light and between the excitation module (100) and the beam splitter module (200); and / or Collimator (120) is located in the optical path of the excitation light and between the excitation module (100) and the beam splitting module (200).

10. The method for measuring the doping concentration distribution of a semiconductor structure using a semiconductor structure doping concentration distribution measurement system according to any one of claims 1-8, characterized in that, The power of the first power light is greater than the power of the second power light.

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