Three-dimensional laser ablation mass spectrometer, combined detection system, and detection method

Abstract

A three-dimensional laser ablation mass spectrometer, a combined detection system, and a detection method. The three-dimensional laser ablation mass spectrometer comprises a laser ablation system, a detection cell, a grinding and polishing system, and a mass spectrometry detection apparatus. The combined detection system comprises a three-dimensional laser ablation mass spectrometer and a Raman laser system. The detection method comprises: performing detection on a sample and then performing sample surface grinding and polishing on the sample. By means of introducing mechanical grinding and polishing, a thermal change layer generated on a surface of a sample due to laser ablation is removed, the high efficiency of laser ablation is utilized, and a possible effect of energy at a focus point during laser ablation on detection is also eliminated.

Description

A three-dimensional laser ablation mass spectrometer, coupled detection system and detection method Technical Field

[0001] The present invention belongs to the technical field of laser ablation, and in particular relates to a three-dimensional laser ablation mass spectrometer, a coupled detection system and a detection method. Background Art

[0002] Raman spectroscopy is a rapid, nondestructive testing technique primarily used for molecular structure research. Laser ablation-inductively coupled plasma-mass spectrometry (LAICP-MS) uses laser ablation as a direct solid sample injection method, combined with mass spectrometry, for elemental analysis. Both analytical methods have a wide range of applications.

[0003] Raman spectroscopy is a type of scattering spectrum. Based on the Raman scattering effect discovered by Indian scientist CV Raman, Raman spectroscopy analyzes scattered light at frequencies different from the incident light to obtain information on molecular vibrations and rotations, and is applied to molecular structure research.

[0004] When a sample is illuminated by monochromatic light with a wavelength much smaller than the sample particle size, most of the light is transmitted in its original direction, while a small portion is scattered at different angles, producing scattered light. When observed in the perpendicular direction, in addition to Rayleigh scattering with the same frequency as the original incident light, there are also a series of symmetrically distributed, very weak Raman spectral lines that are displaced (increased or decreased) from the incident light frequency. This phenomenon is called the Raman effect.

[0005] Raman spectroscopy is very sensitive to molecular bonding and sample structure, resulting in each molecule or sample having its own unique spectral "fingerprint." These "fingerprints" can be used to study and analyze chemical identification, morphology and phase, internal pressure / stress, and composition.

[0006] Raman spectroscopy technology has a wide range of applications in chemistry, materials, physics, polymers, biology, medicine, geology and other fields due to its unique advantages such as rich information, simple sample preparation, low water interference, and no influence from the sample's material form. In addition, Raman spectroscopy analysis is non-destructive to samples, rapid analysis, low maintenance cost, and simple use.

[0007] Laser ablation inductively coupled plasma mass spectrometry uses a laser to emit a laser beam, uses an objective lens to focus the laser on a specific area of ​​the sample, and uses the energy of the pulsed laser to directly form tiny particles of the solid sample, which form an aerosol with the carrier gas. The particles are then plasmatized by an inductively coupled plasma source (ICP) and enter the mass spectrometer for elemental detection.

[0008] Compared with traditional solution analysis, laser ablation inductively coupled plasma mass spectrometry uses laser ablation solid direct analysis technology, which is time-saving, labor-saving and efficient. It reduces the tedious sample pretreatment process, and avoids the introduction of strong acids and other substances in the pretreatment to cause sample contamination and destroy the original state and structure of the sample, while retaining information such as the spatial distribution and depth distribution of the sample components.

[0009] With the gradual maturity of laser ablation systems, laser ablation as a direct solid sampling method, combined with mass spectrometry, has great advantages in trace, ultra-trace element and isotope analysis. It not only plays an important role in the development of micro-area technology in earth sciences, but also extends to materials science, environmental science, marine science, life science and other fields.

[0010] Currently, Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry exist independently as separate analytical methods in the laboratory, and there is no case on the market where the two are combined for application.

[0011] Existing elemental analysis is mainly performed through X-ray fluorescence spectroscopy, but the detection sensitivity is not high and the detectable elements are limited. Another method is ICP-MS analysis, but the existing sample pretreatment requires the introduction of strong acids and other substances for digestion, which will cause sample contamination and destroy the original state and structure of the sample, and it is impossible to obtain in situ information of the sample.

[0012] Wafers are the foundation of modern semiconductors and play a vital role. Trace impurities introduced between components during wafer production can reduce chip yields. Specific contamination issues can lead to various defects in semiconductor devices. For example, alkali metals and alkaline earth metals (Li, Na, K, Ca, Mg, Ba, etc.) can reduce component breakdown voltage. Contamination from transition metals and heavy metals (Fe, Cr, Ni, Cu, Au, Mn, Pb, etc.) can reduce component lifespan or increase dark current during operation.

[0013] There are two main types of wafer surface metal contamination detection technologies. One is TXRF detection, which utilizes a TXRF total reflection fluorescence spectrometer. The TXRF testing principle states that when X-rays are fully reflected, the intensities of the incident and outgoing X-rays are equal, eliminating both coherent and incoherent scattering of the primary X-rays on the reflector. This reduces the scattering background by approximately 3-4 orders of magnitude, significantly improving the peak-to-background ratio (PBR). TXRF utilizes the principle of total X-ray reflection to excite the sample onto a reflector that also serves as a sample holder. This reduces the scattering background and improves the PBR, enabling trace element analysis. Test wafer sample sizes range from 2" to 8" (approximately 100 mm). W targets can test for the following elements (S, Cl, K, Ca, Ti, Cr, Ba, Fe, Ni, Cu, Zn, Pb, Sn), while Mo targets can test for the following elements (Br, Au, Ga, As, Pb, Ta, W, Pt). Simultaneous detection of both W and Mo targets is not possible. The standard inspection point is 3 points, and it can be increased to 5 points if special requirements are met.

[0014] Another type of wafer surface metal contamination detection technology is VPD-ICPMS detection, which is currently the mainstream detection technology in wafer fabs. VPD stands for Vapor Phase Decomposition, and ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry. This technology tests wafer sizes ranging from 2 inches to 12 inches. The testing process includes four steps: 1. The silicon wafer is placed in a VPD chamber and exposed to HF vapor to dissolve the natural oxide or thermally oxidized SiO2 surface layer; 2. A droplet of extraction liquid (typically 250μL of 2% HF / 2% H2O2) is placed on the wafer and then tilted in a carefully controlled manner so that the droplet "sweeps" across the wafer surface; 3. As the extraction droplet moves across the wafer surface, it collects dissolved SiO2 and all contaminant metals; 4. The extraction droplet is transferred from the wafer surface to the ICP-MS system for analysis.

[0015] In summary, the existing technology has the following main problems:

[0016] 1. Raman spectroscopy and laser ablation-inductively coupled plasma-mass spectrometry are independent tests. To obtain both the molecular structure and elemental maps of a sample simultaneously, they must be performed in different laboratories. Because these tests are independent, the molecular structure and elemental maps of the same sample may not completely match their in-situ information, and a one-to-one correspondence cannot be achieved.

[0017] 2. Sample pretreatment requires the introduction of strong acids and other substances for digestion, which will cause sample contamination and destroy the original state and structure of the sample, and it is impossible to obtain the in-situ information of the sample;

[0018] 3. Existing methods cannot accurately obtain a three-dimensional molecular structure map of a sample with in-situ information. In particular, Raman spectroscopy can generally only detect surface information of the sample and cannot perform three-dimensional imaging of the sample, resulting in very low analysis efficiency.

[0019] 4. Silicon wafer contamination test TXRF detection can only detect some elements at a time and cannot detect organic contamination; VPD-ICPMS detection sample pretreatment steps are many and complex, which will introduce other pollutants and interfere with the analysis, and can only perform elemental analysis.

[0020] However, when Raman spectroscopy is directly combined with laser mass spectrometry, during the three-dimensional joint imaging process, the energy generated by laser focusing will affect the materials around the focus, resulting in, for example, element migration and changes in bonding forms (including changes in the composition of organic pollutants), thereby affecting the final imaging results and making the accuracy and precision of the detection results lower than expected.

[0021] Therefore, how to combine Raman spectroscopy with laser ablation inductively coupled plasma mass spectrometry to more accurately obtain in-situ information and improve analysis efficiency is an urgent problem to be solved.

[0022] Summary of the Invention

[0023] In view of this, the purpose of the present invention is to provide a three-dimensional laser ablation mass spectrometer, a coupled detection system and a detection method. By introducing mechanical polishing, the thermally modified layer on the sample surface caused by laser ablation is removed. On the one hand, the high efficiency of laser ablation is utilized, and on the other hand, the possible influence of the energy of the focal point of laser ablation on the detection is eliminated.

[0024] To achieve the above objectives, the present invention provides a three-dimensional laser ablation mass spectrometer and a laser ablation system, wherein the laser ablation system is used to emit ablation laser, and the laser ablation system includes a three-dimensional galvanometer system;

[0025] The detection cell includes a detection cell housing, a stage, a sample door, an air inlet, an air outlet, an ablation laser window, and a vacuum pump. The stage is used to hold the sample and is disposed within the detection cell housing. The sample door, air inlet, air outlet, and ablation laser window are disposed on the detection cell housing.

[0026] A grinding and polishing system, wherein the grinding and polishing system is used to grind and polish the surface of the sample scanned by the laser ablation system;

[0027] A mass spectrometry detection device is used to perform mass spectrometry detection on the aerosol generated by the laser ablation system.

[0028] Preferably, it also includes a wafer robot, which is used for loading and unloading wafers.

[0029] Preferably, the laser ablation system further comprises a laser emitter and a field lens; the laser emitter emits ablation laser and focuses it on the sample surface;

[0030] The three-dimensional galvanometer system includes a moving lens, a focusing lens, an X-axis galvanometer and a Y-axis galvanometer;

[0031] The movable lens can move axially, and the position where the ablation laser is focused is changed on the sample surface along the Z axis by adjusting the distance between the movable lens and the focusing lens;

[0032] The X-axis galvanometer and the Y-axis galvanometer can respectively perform high-frequency reciprocating rotation around the axis, and the X-axis galvanometer and the Y-axis galvanometer are used to adjust the focusing position in the horizontal direction of the sample surface.

[0033] Preferably, the grinding and polishing system includes a grinding and polishing head, a clamp, a grinding and polishing disc, a motor and a PLC control module, the grinding and polishing disc is used to hold the sample, the clamp is used to fix the sample held on the grinding and polishing disc, and the PLC control module is used to control the grinding and polishing system.

[0034] Another aspect of the present invention provides a combined detection system, comprising: the three-dimensional laser ablation mass spectrometer as described above; a Raman laser system, the Raman laser system being configured to emit Raman detection laser light and detect Raman scattered light;

[0035] The detection cell is a combined detection cell, which also includes a Raman laser window. The stage is a movable stage, which is also used to switch and position the sample between the positions corresponding to the Raman laser window and the ablation laser window. The movable stage includes a grating scale feedback control system, and the Raman laser window is opened on the detection cell housing.

[0036] Preferably, the combined detection cell further comprises a sample observation window, and the sample observation window is used for quickly observing the position of the sample.

[0037] Another aspect of the present invention provides a detection method of a three-dimensional laser ablation mass spectrometer, using the three-dimensional laser ablation mass spectrometer as described above, wherein the sample is a wafer.

[0038] Preferably, the method comprises the following steps:

[0039] Step S1: placing a sample into the detection cell and fixing it on the stage at a position corresponding to the ablation laser window, and replacing the gas in the detection cell with a carrier gas;

[0040] Step S2: focusing the ablation laser on the sample surface and performing a two-dimensional laser ablation-mass spectrometry scan, wherein the two-dimensional laser ablation-mass spectrometry scan includes performing several laser ablations and sending the aerosol generated by the laser ablation into a mass spectrometry detection device for detection;

[0041] Step S3: Turn off the carrier gas and send the sample into the polishing system, which automatically polishes and cleans the eroded surface of the sample and blows it dry at room temperature;

[0042] Step S4: Repeat steps S1 to S3 until the three-dimensional scan is completed;

[0043] Step S5: perform data processing.

[0044] Another aspect of the present invention provides a detection method of a combined detection system, using the combined detection system as described above.

[0045] Preferably, the method comprises the following steps:

[0046] Step S1: placing a sample into the combined detection cell, fixing the sample on the movable stage, and performing gas replacement in the combined detection cell with a carrier gas;

[0047] Step S2: moving the sample to a position corresponding to the Raman laser window by the movable stage;

[0048] Step S3: focusing the Raman detection laser on the sample surface to perform a two-dimensional Raman spectrum scan;

[0049] Step S4: moving the sample to a position corresponding to the ablation laser window by the movable stage;

[0050] Step S5: focusing the ablation laser on the sample surface and performing a two-dimensional laser ablation-mass spectrometry scan, wherein the two-dimensional laser ablation-mass spectrometry scan includes performing several laser ablations and sending the aerosol generated by the laser ablation into a mass spectrometry detection device for detection;

[0051] Step S6: Turn off the carrier gas and send the sample into the polishing system, which automatically polishes and cleans the eroded surface of the sample and blows it dry at room temperature;

[0052] Step S7: Repeat steps S1 to S6 until the three-dimensional scan is completed;

[0053] Step S8: perform data processing.

[0054] Preferably, the sample is a wafer;

[0055] Preferably, the sample is a metal-organic framework compound;

[0056] Preferably, the sample is a new semiconductor material, such as gallium nitride, gallium arsenide, and silicon carbide.

[0057] The present invention has the following beneficial effects:

[0058] 1) The present invention removes the thermally modified layer on the sample surface caused by laser ablation by introducing mechanical polishing. This not only takes advantage of the high efficiency of laser ablation, but also eliminates the potential impact of the energy at the laser ablation focus on detection.

[0059] 2) The present invention can be applied to online automatic detection of silicon wafers, and can detect organic and elemental contamination of wafers. No sample pretreatment is required before detection, and it can meet the requirements of real-time and rapid online detection of silicon wafer surface particles and the entire contamination composition in the integrated circuit production process, without causing secondary contamination or damage to the silicon wafers.

[0060] 3) The combined detection method of the present invention can simultaneously obtain a three-dimensional molecular structure diagram and a three-dimensional element imaging diagram of the sample with in-situ information, and the three dimensions can present a corresponding relationship based on the in-situ information. When detecting the sample, the laser ablation system is used to obtain the aerosol required for mass spectrometry detection on the one hand, and also plays a surface ablation role on the other hand, so that the Raman laser system can detect the internal structural information below the surface of the sample. Mechanical polishing avoids the influence of element migration in the thermally variable layer on the mass spectrum on the one hand, and avoids the influence of the chemical structure with poor heat resistance in the thermally variable layer on the Raman spectrum on the other hand. Moreover, since the scanning speed of the laser ablation system is greatly accelerated, there is no need for confocal Raman laser system-laser ablation system, which simplifies the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0062] FIG1 is a schematic structural diagram of a first embodiment of the present invention;

[0063] FIG2 is a schematic structural diagram of a three-dimensional galvanometer system according to a first embodiment of the present invention;

[0064] FIG3 is a schematic flow chart of a detection method according to a first embodiment of the present invention;

[0065] FIG4 is a schematic structural diagram of a second embodiment of the present invention;

[0066] FIG5 is a schematic structural diagram of a combined detection cell according to a second embodiment of the present invention;

[0067] FIG6 is a schematic flow chart of the combined detection method according to the second embodiment of the present invention;

[0068] Among them: 101 Raman detection laser emitter; 102 interference filter; 103 power attenuator; 104 light source polarizer; 105 light source reflector; 106 Rayleigh filter; 107 microscope system; 108 confocal pinhole; 109 slit; 110 grating; 111 detector; 112 detection polarizer; 113 detection reflector; 201 ablation laser emitter; 202 3D galvanometer system; 2021 moving lens; 2022 focusing lens; 2023 X-axis galvanometer; 2024 Y-axis galvanometer; 203 field mirror; 300 detection cell; 301 sample; 302 carrier gas; 303 sample cup; 304 stage; 305 aerosol; 401 polishing head; 402 clamp; 403 water nozzle; 404 polishing disc; 405 motor; 406 PLC control module. DETAILED DESCRIPTION

[0069] One of the core elements of the present invention lies in a three-dimensional laser ablation mass spectrometer, a coupled detection system, and a detection method. By introducing mechanical polishing, the thermally modified layer on the sample surface caused by laser ablation is removed. On the one hand, the high efficiency of laser ablation is utilized, and on the other hand, the possible impact of the energy of the laser ablation focus on detection is eliminated.

[0070] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0071] Example 1

[0072] Referring first to Figure 1, the 3D laser ablation mass spectrometer of this embodiment includes a fully automated polishing system, a laser ablation system, a detection cell, and a mass spectrometer. The laser ablation system emits the ablation laser and includes a 3D galvanometer system. The fully automated polishing system polishes the sample surface scanned by the laser ablation system. The mass spectrometer detects the aerosols generated by the laser ablation system through mass spectrometry. Furthermore, this embodiment includes a wafer robot (not shown) for loading and unloading wafers.

[0073] As shown in Figure 1, the fully automatic grinding and polishing system includes a grinding and polishing head 401, a clamper 402, a water nozzle 403, a grinding and polishing disc 404, a motor 405 and a PLC control module 406. The grinding and polishing head 401 is used to grind and polish the sample, the grinding and polishing disc 404 is used to hold the sample, the clamper 402 is used to fix the sample held on the grinding and polishing disc 404, the water nozzle 403 is used to clean the sample after grinding and polishing, the motor 405 is used to drive the aforementioned components, and the PLC control module 406 is used to control the operation of the various components of the fully automatic grinding and polishing system.

[0074] As shown in Figure 2, the three-dimensional galvanometer system 202 includes a movable lens 2021, a focusing lens 2022, an X-axis galvanometer 2023 and a Y-axis galvanometer 2024; the movable lens 2021 can move axially, and the movable lens 2021 changes the focusing position of the ablation laser along the Z-axis on the surface of the sample 301 by adjusting the distance between the movable lens 2021 and the focusing lens 2022; the X-axis galvanometer 2023 and the Y-axis galvanometer 2024 can respectively perform high-frequency reciprocating rotation around the axis, and the X-axis galvanometer 2023 and the Y-axis galvanometer 2024 are used to adjust the focusing position in the horizontal direction on the surface of the sample 301.

[0075] The detection cell 300 includes a detection cell housing, a stage 304, a sample door, an air inlet, an air outlet, an ablation laser window, and a vacuum pump.

[0076] This embodiment also discloses a detection method using the above-mentioned three-dimensional laser ablation mass spectrometer, as shown in FIG3 :

[0077] 1. Place the wafer on the wafer rack;

[0078] 2. The computer issues a command, which opens the sample door through the PLC control module and controls the wafer manipulator to move the wafer from the wafer rack to the wafer holder in the sample pool;

[0079] 3. The sample door is closed and sealed;

[0080] 4. The detection pool is ventilated; the vacuum pump automatically starts to evacuate the pool, and when the set vacuum degree is reached, the vacuum pump stops evacuating the pool and the carrier gas is introduced; when the pressure in the detection pool reaches the set value, the vacuum pump automatically starts to evacuate the pool, and when the set vacuum degree is reached, the vacuum pump stops evacuating the pool and the carrier gas is introduced, and this process is repeated three times;

[0081] 5. The computer automatically and precisely adjusts the moving stage to achieve laser focus on the wafer. The microscope system is equipped with a high-resolution color camera that automatically captures and stores images. The computer precisely controls the three-dimensional movement of the sample to be tested, and the laser ablation system starts working according to the pre-set relevant working parameters (laser frequency, energy density, spot size and carrier gas flow rate, as well as X, Y and Z coordinate parameters, etc.). The laser module generates a laser beam, and the X and Y axes deflect at high speed. The laser beam enters the field lens and is focused on the working surface. The "Z" axis automatically adjusts the focus at high speed and precision to perform three-dimensional laser ablation of the sample.

[0082] 6. Laser ablation directly forms tiny particles in the sample, which form aerosols with the carrier gas. The particles are then plasmatized by an inductively coupled plasma source (ICP) and then enter the mass spectrometer for elemental detection to form a high-quality elemental plane map of the sample.

[0083] 7. After the laser ablation is completed, the sample door automatically opens, the carrier gas is turned off, the wafer robot moves the wafer to the wafer rack outside the detection pool, and the sample chamber door automatically closes;

[0084] 8. The wafer robot takes the wafer out of the wafer rack and places it in the gripper of the fully automatic grinding and polishing system for fixation;

[0085] 9. The fully automatic grinding and polishing system automatically polishes, cleans, and dries the wafers at room temperature;

[0086] 10. After polishing is completed, the wafer robot moves the wafer to the wafer rack;

[0087] 11. Repeat steps 2 to 10 in the method until the analysis task is completed;

[0088] 12. Take out the wafer sample, put it into the sample box, mark it, and store it in the designated location;

[0089] 13. Turn off the carrier gas and system devices according to standard procedures

[0090] 14. After the computer system automatically processes the data, it generates a three-dimensional elemental image of the sample with in-situ information.

[0091] Compared to traditional mechanical polishing, laser ablation scanning can more quickly remove sample layers of a specific thickness. However, due to the focused energy at the laser's focal point, a thermal effect can create a thermally altered region on the surface after ablation (a thermally altered layer is formed after completing a two-dimensional ablation scan). The bonding structure of the materials within this region changes to some extent. For wafers requiring high inspection accuracy, dopant elements may also migrate across the surface or laterally, potentially interfering with inspection results. This embodiment uses mechanical polishing to remove the thermally altered layer on the surface to eliminate its effects. Since the thermally altered layer itself is extremely thin, polishing it efficiently improves its processing efficiency.

[0092] In some other applications, those skilled in the art may also scan only a few designated depths or depth intervals, and may perform grinding and polishing on the surface after jumping from the previous depth to the next depth through multiple two-dimensional ablation steps.

[0093] Example 2

[0094] The difference between this embodiment and the first embodiment is that a Raman laser system is additionally added. The Raman laser system and the laser ablation system can share the same detection cell 300, that is, a combined detection cell.

[0095] As shown in FIG4 , the Raman laser system of this embodiment is a laser confocal micro-Raman spectrometer, which includes: a Raman detection laser emitter 101, an interference filter 102, a power attenuator 103, a polarizer, a reflector, a Rayleigh filter 106, a microscope system 107, a confocal pinhole 108, a slit 109, a grating 110 and a detector 111. The polarizer includes a light source polarizer 104 and a detection polarizer 112, and the reflector includes a light source reflector 105 and a detection reflector 113. The laser ablation system includes a three-dimensional galvanometer system, an ablation laser emitter 201 and a field lens 203. The ablation laser emitter 201 emits an ablation laser focused on the surface of the sample 301. The Raman detection laser emitter 101 emits a light source polarizer 104 and a detection polarizer 112. The reflector includes a light source reflector 105 and a detection reflector 113. The laser ablation system includes a three-dimensional galvanometer system, an ablation laser emitter 201 and a field lens 203. The ablation laser emitter 201 emits an ablation laser focused on the surface of the sample 301. The emitted laser beam is focused on the surface of the sample 301 through the first optical path, and the Raman detection laser emitter 101, the interference filter 102, the power attenuator 103, the light source polarizer 104, the light source reflector 105 and the Rayleigh filter 106 are arranged on the first optical path; the Raman scattered light generated on the surface of the sample 301 enters the detector 111 through the second optical path, and the Rayleigh filter 106, the detection polarizer 112, the detection reflector 113, the confocal pinhole 108, the slit 109, the grating 110 and the detector 111 are arranged on the second optical path; the first optical path and the second optical path share the microscope system 107, the laser beam is reflected on the Rayleigh filter 106 through the first optical path, and the Raman scattered light passes through the Rayleigh filter 106 through the second optical path.

[0096] Since the laser ablation system of this embodiment adopts a three-dimensional galvanometer system 202 that can switch the focusing position at high speed, the speed of laser ablation two-dimensional scanning is greatly accelerated. Therefore, the detection strategy can also be changed from the strategy of Raman single-point detection-mass spectrometry single-point detection-switching detection point to the strategy of Raman two-dimensional scanning-switching detection window-mass spectrometry two-dimensional scanning, which greatly simplifies the device and avoids the difficulty of confocalization.

[0097] As shown in FIG5 , the detection cell 300 includes a detection cell housing, a stage 304, a sample door 313, an air inlet 306, an air outlet 307, a Raman laser window 309, an ablation laser window 310, and a vacuum pump 308. The stage 304 is a movable stage that can switch and position the sample 301 between the positions corresponding to the Raman laser window 309 and the ablation laser window 310. The stage 304 also includes a grating scale feedback control system. The detector housing is a sealed housing, and the stage 304 is disposed within the detection cell housing. The sample door 313, the air inlet 306, the air outlet 307, the Raman laser window 309, and the ablation laser window 310 are disposed on the detection cell housing. In a preferred embodiment, a sample observation window 311 can also be provided on the detection cell housing for quickly observing the sample position.

[0098] This embodiment also discloses a detection method using the above-mentioned combined detection system, as shown in FIG6 :

[0099] 1. Place the wafer on the wafer rack;

[0100] 2. The computer issues a command, which opens the sample door through the PLC control module and controls the wafer manipulator to move the wafer from the wafer rack to the wafer holder in the sample pool;

[0101] 3. The sample door is closed and sealed;

[0102] 4. The detection pool is ventilated; the vacuum pump automatically starts to evacuate the pool, and when the set vacuum degree is reached, the vacuum pump stops evacuating the pool and the carrier gas is introduced; when the pressure in the detection pool reaches the set value, the vacuum pump automatically starts to evacuate the pool, and when the set vacuum degree is reached, the vacuum pump stops evacuating the pool and the carrier gas is introduced, and this process is repeated three times;

[0103] 5. After the ventilation is completed, the stage is moved to move the wafer to the position of the Raman laser window 309;

[0104] 6. The computer automatically and precisely adjusts the moving stage to achieve laser focusing on the wafer. At the same time, the microscope system is equipped with a high-resolution color camera that can display stored images on the computer. The computer precisely controls the movement of the stage 304 to enable the sample to be tested to move in three dimensions with high precision, and selects the sample micro-region that emits Raman scattered light. The Raman detection laser emitted by the laser transmitter is purified by the monochromator, and then the optical path is changed by the reflector and then accurately focused on the sample by the objective lens; the Raman scattered light emitted by the sample is then accurately imaged on the incident slit of the monochromator by the focusing lens, and after grating separation, it enters the detector for detection, and obtains comprehensive information on the intensity of the Raman signal in a specific range, which can indicate high-resolution images of relevant information such as surface material composition and content distribution;

[0105] 7. After Raman imaging, the stage 304 is controlled to move to the ablation laser window;

[0106] 8. The laser ablation system starts working according to the pre-set working parameters (laser frequency, energy density, spot size, carrier gas flow rate, and X, Y, and Z coordinate parameters). The laser module generates a laser beam, which deflects at high speed on the X and Y axes. The laser beam enters the field lens and is focused onto the work surface. The Z axis automatically adjusts the focus at high speed to perform three-dimensional laser ablation of the sample.

[0107] 9. Laser ablation directly forms tiny particles in the sample, which form an aerosol with the carrier gas. The particles are then plasmatized by an inductively coupled plasma source (ICP) and then enter the mass spectrometer for elemental detection to form a high-quality elemental plane map of the sample.

[0108] 10. After the laser ablation is completed, the sample door automatically opens, the carrier gas is turned off, the wafer manipulator moves the wafer to the wafer rack outside the detection pool, and the sample chamber door automatically closes;

[0109] 11. The wafer robot takes the wafer out of the wafer rack and places it in the clamp of the fully automatic grinding and polishing system for fixation;

[0110] 12. The fully automatic grinding and polishing system automatically polishes, cleans and dries the wafers at room temperature;

[0111] 13. After polishing is completed, the wafer robot moves the wafer to the wafer rack;

[0112] 14. Repeat steps 2 to 13 until the analysis is complete.

[0113] 15. Take out the wafer sample, put it into the sample box, mark it, and store it in the designated location;

[0114] 16. Turn off the carrier gas and all system devices according to standard procedures;

[0115] 17. After the computer system automatically processes the data, it will give the sample's 3D Raman spectrum with in-situ information and 3D element imaging, as well as the 3D Raman spectrum (molecular structure) at the same position of the sample.

[0116] In some other applications, those skilled in the art may also scan only a few designated depths or depth intervals, and may perform grinding and polishing on the surface after jumping from the previous depth to the next depth through multiple two-dimensional ablation steps.

[0117] In this embodiment, since Raman spectroscopy is a surface detection technology with a relatively small detection depth, when used in conjunction with laser ablation mass spectrometry, the process of ablation and removal of the sample surface can be used to complete an in-depth detection scan of the interior of the sample.

[0118] For wafer samples, this embodiment can further obtain relevant information such as its bonding structure through Raman spectroscopy; in some other embodiments, if only the surface of the wafer sample needs to be tested, such as to detect its surface contamination, there is no need for grinding or polishing, and comparison information can be obtained after only one Raman test and one laser ablation.

[0119] In addition to wafer-type samples, solid samples with structures containing chemical bonds with low thermal tolerance, such as metal-organic frameworks (MOFs), may also experience changes in their surface chemical structure due to the energy of the focused point when subjected to laser ablation. Therefore, the mechanical polishing of this embodiment can also avoid the interference of the above-mentioned thermal change effects on the detection results. In addition, if the sample is made to the same specifications as the wafer, it can be compatible with wafer-related handling equipment to simplify the process. For solid samples such as biological samples and molecular crystals, since their intermolecular forces can absorb the energy of the focused laser, polishing is generally not required.

[0120] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0121] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-dimensional laser ablation mass spectrometer, characterized in that: include: A laser ablation system, the laser ablation system is used to emit ablation laser, and the laser ablation system includes a three-dimensional galvanometer system; A detection cell, the detection cell comprising a detection cell housing, a stage, a sample door, an air inlet, an air outlet, an ablation laser window and a vacuum pump, the stage being used to hold samples, the stage being arranged in the detection cell housing, the sample door, the air inlet, the air outlet and the ablation laser window being arranged on the detection cell housing; A grinding and polishing system, wherein the grinding and polishing system is used to grind and polish the surface of the sample after being scanned by the laser ablation system; A mass spectrometry detection device is used to perform mass spectrometry detection on the aerosol generated by the laser ablation system.

2. The three-dimensional laser ablation mass spectrometer according to claim 1, characterized in that: It also includes a wafer robot, which is used for loading and unloading wafers.

3. The three-dimensional laser ablation mass spectrometer according to claim 1, characterized in that: The laser ablation system also includes a laser transmitter and a field lens; the laser transmitter transmits ablation laser and focuses it on the sample surface; The three-dimensional galvanometer system includes a moving lens, a focusing lens, an X-axis galvanometer and a Y-axis galvanometer; The movable lens can move axially, and the movable lens changes the focusing position of the ablation laser on the sample surface along the Z axis by adjusting the distance between the movable lens and the focusing lens; The X-axis galvanometer and the Y-axis galvanometer can respectively perform high-frequency reciprocating rotation around the axis, and the X-axis galvanometer and the Y-axis galvanometer are used to adjust the focusing position in the horizontal direction of the sample surface.

4. The three-dimensional laser ablation mass spectrometer according to claim 1, characterized in that: The grinding and polishing system includes a grinding and polishing head, a clamp, a grinding and polishing disc, a motor and a PLC control module. The grinding and polishing disc is used to hold samples, the clamp is used to fix the samples held on the grinding and polishing disc, and the PLC control module is used to control the grinding and polishing system.

5. A combined detection system, characterized in that: include: The three-dimensional laser ablation mass spectrometer according to any one of claims 1 to 4; a Raman laser system, wherein the Raman laser system is used to emit Raman detection laser and detect Raman scattered light; The detection cell is a combined detection cell, and the combined detection cell also includes a Raman laser window. The stage is a mobile stage, and the mobile stage is also used to move the sample between the positions corresponding to the Raman laser window and the ablation laser window. Switching positioning, the movable stage includes a grating ruler feedback control system, and the Raman laser window is opened on the detection cell housing.

6. The combined detection system according to claim 5, characterized in that: The combined detection cell also includes a sample observation window, and the sample observation window is used to quickly observe the sample position.

7. A detection method for a three-dimensional laser ablation mass spectrometer, characterized in that: Using the three-dimensional laser ablation mass spectrometer as described in any one of claims 1 to 4, the sample is a wafer.

8. The detection method according to claim 7, characterized in that: The steps include: Step S1: placing a sample into the detection cell and fixing it on the stage at a position corresponding to the ablation laser window, and replacing the gas in the detection cell with a carrier gas; Step S2: focusing the ablation laser on the sample surface and performing two-dimensional laser ablation-mass spectrometry scanning, wherein the two-dimensional laser ablation-mass spectrometry scanning includes performing several laser ablations and sending the aerosol generated by the laser ablation to a mass spectrometry detection device for detection; Step S3: Turn off the carrier gas and send the sample into the polishing system, which automatically polishes and cleans the surface of the sample after erosion, and blows it dry at room temperature; Step S4: repeat steps S1 to S3 until the three-dimensional scanning is completed; Step S5: perform data processing.

9. A detection method using a combined detection system, characterized in that: Use the combined detection system as described in claim 5 or 6.

10. The detection method according to claim 9, characterized in that: The steps include: Step S1: placing a sample into the combined detection cell, fixing the sample on the movable stage, and replacing the gas in the combined detection cell with a carrier gas; Step S2: moving the sample to a position corresponding to the Raman laser window by the movable stage; Step S3: focusing the Raman detection laser on the sample surface to perform a two-dimensional Raman spectrum scan; Step S4: moving the sample to a position corresponding to the ablation laser window by the movable stage; Step S5: focusing the ablation laser on the sample surface and performing two-dimensional laser ablation-mass spectrometry scanning. Photoablation-mass spectrometry scanning includes several laser ablations and sending the aerosol generated by the laser ablation to a mass spectrometry detection device for detection; Step S6: Turn off the carrier gas and send the sample into the polishing system, which automatically polishes and cleans the surface of the sample after erosion, and blows it dry at room temperature; Step S7: repeating steps S1 to S6 until the three-dimensional scanning is completed; Step S8: perform data processing.

11. The detection method according to claim 9, characterized in that: The sample is a wafer or a metal organic framework compound or a new semiconductor material.

Images