WO2024250765A1 - Three-dimensional laser ablation mass spectrometer, combined detection system, and detection method - Google Patents

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

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

Raman spectroscopy is a fast non-destructive testing technology, mainly used for molecular structure research; laser ablation inductively coupled plasma mass spectrometry is a technology that uses laser ablation as a direct solid sampling method and mass spectrometry to perform sample elemental analysis. Both analytical methods have a wide range of applications.

Raman spectroscopy is a type of scattering spectrum. Raman spectroscopy is based on the Raman scattering effect discovered by Indian scientist C.V. Raman. It analyzes the scattering spectrum with different frequencies from the incident light to obtain information on molecular vibration and rotation, and is applied to the study of molecular structure.

When a sample is illuminated with monochromatic light whose wavelength is much smaller than the particle size of the sample, most of the light will be transmitted in the original direction, while a small part will be scattered at different angles to produce scattered light. When observed in the vertical 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 spectra that are displaced (frequency shift increases or decreases) from the incident light frequency. This phenomenon is called the Raman effect.

Raman spectroscopy is very sensitive to molecular bonding and sample structure, so each molecule or sample has its own unique spectral "fingerprint". These "fingerprints" can be used for chemical identification, morphology and phase, internal pressure/stress and composition research and analysis.

Raman spectroscopy technology is widely used in chemistry, materials, physics, polymers, biology, medicine, geology and other fields due to its rich information, simple sample preparation, little interference from water, and no influence from the material form of the sample. In addition, Raman spectroscopy analysis has unique advantages such as no damage to samples, rapid analysis, low maintenance cost and simple use.

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, uses the energy of the pulsed laser to directly form tiny particles of the solid sample, forms an aerosol with the carrier gas, and then uses an inductively coupled plasma source (ICP) to plasmatize the particles and enter the mass spectrometer for element detection.

Compared with traditional solution analysis, laser ablation inductively coupled plasma mass spectrometry uses laser ablation solid to directly analyze The technology is time-saving, labor-saving and efficient, reducing the tedious process of sample pretreatment. At the same time, it 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, and retains information such as the spatial distribution and depth distribution of sample components.

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.

At present, Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry exist independently as separate analysis methods in laboratories, and there is no case in the market where the two are combined for application.

Existing elemental analysis is mainly performed through X-ray fluorescence spectroscopy, but the detection sensitivity is not high and the detected 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 the in-situ information of the sample.

Wafers are the foundation of modern semiconductors and play a huge role. Trace impurity elements introduced between components during wafer production may reduce the chip qualification rate; specific pollution problems can lead to different defects in semiconductor devices, for example: alkali metals or alkaline earth metals (Li, Na, K, Ca, Mg, Ba, etc.) will lead to a decrease in component breakdown voltage; transition metal and heavy metal (Fe, Cr, Ni, Cu, Au, Mn, Pb, etc.) pollution can reduce the service life of components or increase the dark current when the components are working, etc.

There are two main types of existing wafer surface metal contamination detection technologies. One is TXRF detection technology, which uses TXRF total reflection fluorescence spectrometer for detection. TXRF test principle: When X-rays are fully emitted, the intensity of the incident X-rays and the outgoing X-rays is equal, eliminating the coherent and incoherent scattering of the original X-rays on the reflector, reducing the scattering background by about 3-4 orders of magnitude, thereby greatly improving the peak-to-background ratio. TXRF is an analytical technology that uses the principle of total X-ray reflection to coat the sample into a thin layer (nm level) on the reflector and sample holder for excitation to reduce the scattering background and improve the peak-to-background ratio to achieve trace element analysis. The test wafer sample size is 2 inches to 8 inches. The W target can test the following elements: (S, Cl, K, Ca, Ti, Cr, Ba, Fe, Ni, Cu, Zn, Pb, Sn), and the Mo target can test the following elements: (Br, Au, Ga, As, Pb, Ta, W, Pt). The W target and Mo target elements cannot be detected at the same time. The standard inspection point is 3 points, and it can be increased to 5 points if special requirements are met.

Another type of wafer surface metal contamination detection technology is VPD-ICPMS detection, which is the mainstream detection technology in wafer fabs. VPD: Vapor Phase Decomposition Chemical Meteorological Decomposition, ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry. This technology tests wafer sizes of 2 inches to 12 inches. The test process includes four steps: 1. Place the silicon wafer in the VPD chamber and expose it to HF vapor to dissolve the natural oxide or thermally oxidized SiO2 surface layer; 2. Place an extraction droplet (usually 250μL of 2% HF/2% H2O2) on the wafer and then tilt it 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. Transfer the extraction droplet from the wafer surface to the ICP-MS system for analysis.

In summary, the prior art has the following main problems:

1. Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry are both independent tests. If you want to get the molecular structure diagram and element diagram of the sample at the same time, you must test them in different laboratories. Because they are separate and independent tests, the molecular structure diagram and element diagram of the same sample cannot completely match the in-situ information and cannot present a one-to-one correspondence.

2. Pretreatment of samples 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 samples, and it is impossible to obtain the in-situ information of the samples;

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

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 complicated, which will introduce other pollutants and interfere with the analysis, and can only perform elemental analysis.

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, causing, 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.

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.

Summary of the invention

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 thermal deformation 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.

To achieve the above-mentioned object, the present invention provides a three-dimensional laser ablation mass spectrometer, 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;

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.

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

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;

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.

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 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.

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 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.

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

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.

Preferably, the method comprises the following steps:

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.

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

Preferably, the method comprises the following steps:

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, 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 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.

Preferably, the sample is a wafer;

Preferably, the sample is a metal organic framework compound;

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

The present invention has the following beneficial effects:

1) The present invention removes the thermally modified layer on the sample surface caused by laser ablation by introducing mechanical grinding and polishing, which not only utilizes the high efficiency of laser ablation, but also eliminates the influence of the energy of the laser ablation focus on the detection;

2) The present invention can be applied to online automatic detection of silicon wafers, and can detect organic pollution and element pollution of wafers. There is no need to pre-treat the sample before detection, and it can meet the requirements of real-time and rapid online detection of silicon wafer surface particles and the entire pollution components in the integrated circuit production process, and will not cause secondary pollution or damage to the silicon wafer;

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 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 on the other hand, it also plays a role in surface ablation, so that the Raman laser system can detect the internal structural information below the surface of the sample, and mechanical polishing avoids the influence of element migration in the thermal variable layer on the mass spectrum on the other hand, and avoids the influence of the chemical structure with poor heat resistance in the thermal variable layer on the Raman spectrum; and because the scanning speed of the laser ablation system is greatly accelerated, there is no need for confocalization of the Raman laser system-laser ablation system, which simplifies the device.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can also refer to the embodiments of the present invention without creative work. From these drawings the other drawings are derived.

FIG1 is a schematic diagram of the structure of Embodiment 1 of the present invention;

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

FIG3 is a schematic diagram of a flow chart of a detection method according to Embodiment 1 of the present invention;

FIG4 is a schematic diagram of the structure of Embodiment 2 of the present invention;

FIG5 is a schematic diagram of the structure of a combined detection cell according to a second embodiment of the present invention;

FIG6 is a schematic flow chart of a combined detection method according to Embodiment 2 of the present invention;

in:
101 Raman detection laser emitter; 102 interference filter; 103 power attenuation plate; 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 three-dimensional 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 grinding and polishing head; 402 clamp; 403 water nozzle; 404 grinding and polishing disc; 405 motor; 406 PLC control module.

DETAILED DESCRIPTION

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 thermal deformation 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.

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

Embodiment 1

Please refer to FIG1 first. The three-dimensional laser ablation mass spectrometer of this embodiment includes a fully automatic grinding and polishing system. The laser ablation system, a detection cell and a mass spectrometry detection device are used to emit ablation laser. The laser ablation system includes a three-dimensional vibration The laser ablation system comprises a fully automatic grinding and polishing system for grinding and polishing the sample surface after being scanned by the laser ablation system; and a mass spectrometer detection device for performing mass spectrometer detection on the aerosol generated by the laser ablation system. In addition, the present embodiment further comprises a wafer manipulator (not shown in the figure), which is used for loading and unloading wafers.

As shown in Figure 1, the fully automatic grinding and polishing system includes a grinding and polishing head 401, a clamp 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 clamp 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.

As shown in FIG2 , 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 on the surface of the sample 301 along the Z-axis 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.

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.

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

1. Place the wafer on the wafer rack;

2. The computer issues a command to open the sample door through the PLC control module and control the wafer manipulator to move the wafer from the wafer rack to the wafer holder in the sample pool;

3. The sample door is closed and sealed;

4. The detection pool is ventilated; the vacuum pump automatically starts to evacuate the pool, and stops evacuating the pool after reaching the set vacuum degree, and introduces the carrier gas; when the pressure in the detection pool reaches the set value, the vacuum pump automatically starts to evacuate the pool, and stops evacuating the pool after reaching the set vacuum degree, and introduces the carrier gas, and repeats this process 3 times;

5. The computer automatically and precisely adjusts the moving stage to achieve laser focusing on the wafer. The microscope system is equipped with a high-resolution color camera to automatically capture and store 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). The laser module generates a laser beam, the X-axis and Y-axis deflect at high speed, the laser beam enters the field lens and is focused onto the working surface, and the "Z" axis automatically adjusts the focus at high speed and precision to perform three-dimensional laser ablation of the sample;

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

7. 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 compartment door automatically closes;

8. The wafer robot takes the wafer out of the wafer rack and puts it into the clamp of the fully automatic grinding and polishing system for fixation;

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

10. After polishing, the wafer robot moves the wafer to the wafer rack;

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

12. Take out the wafer samples, put them into the sample box, mark them, and store them in the designated location;

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

14. After the computer system automatically processes the data, it gives a three-dimensional elemental imaging map of the sample with in-situ information.

Compared with traditional mechanical polishing, laser ablation scanning can remove sample layers of specific thickness faster, but due to the energy focusing at the laser focus point, it will have a thermal effect to produce a thermally variable area on the surface after ablation (a thermally variable layer is formed after completing a layer of two-dimensional ablation scanning). The bonding mode of the material in this area will change to a certain extent. For wafers with high detection accuracy requirements, doping elements may also migrate on the surface or laterally, which may interfere with the detection results. This embodiment removes the thermally variable layer on the surface through mechanical polishing to eliminate its influence, and the thickness of the thermally variable layer itself is extremely small, so the grinding and polishing treatment efficiency is relatively high.

In some other applications, technicians in this field 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.

Embodiment 2

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

As shown in FIG4 , the Raman laser system of this embodiment is a laser confocal Raman microscope. The micro-Raman spectrometer comprises: a Raman detection laser emitter 101, an interference filter 102, a power attenuation plate 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 comprises a light source polarizer 104 and a detection polarizer 112, the reflector comprises a light source reflector 105 and a detection reflector 113; the laser ablation system comprises a three-dimensional galvanometer system, an ablation laser emitter 201 and a field lens 203; the ablation laser emitter 201 emits an ablation laser and focuses it on the surface of a sample 301; the laser beam emitted by the Raman detection laser emitter 101 is focused on the sample 301 through a first optical path. 01 surface, a Raman detection laser emitter 101, an interference filter 102, a power attenuation plate 103, a light source polarizer 104, a light source reflector 105 and a Rayleigh filter 106 are arranged on a first optical path; the Raman scattered light generated on the surface of the sample 301 enters the detector 111 through a 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 a 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.

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 Raman single-point detection-mass spectrometry single-point detection-switching detection point strategy to Raman two-dimensional scanning-switching detection window-mass spectrometry two-dimensional scanning strategy, which greatly simplifies the device and avoids the difficulty of confocalization.

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 mobile stage, which can switch and position the sample 301 between the positions corresponding to the Raman laser window 309 and the ablation laser window 310, and the stage 304 also includes a grating ruler feedback control system; the detector housing is a sealed housing, the stage 304 is arranged in the detection cell housing, and the sample door 313, the air inlet 306, the air outlet 307, the Raman laser window 309, and the ablation laser window 310 are arranged on the detection cell housing. In a preferred embodiment, a sample observation window 311 can also be arranged on the detection cell housing for quickly observing the sample position.

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

1. Place the wafer on the wafer rack;

2. The computer issues a command to open the sample door through the PLC control module and control the wafer robot to move the wafer from The wafer rack is moved to the wafer fixing seat in the sample pool;

3. The sample door is closed and sealed;

4. The detection pool is ventilated; the vacuum pump automatically starts to evacuate the pool, and stops evacuating the pool after reaching the set vacuum degree, and introduces the carrier gas; when the pressure in the detection pool reaches the set value, the vacuum pump automatically starts to evacuate the pool, and stops evacuating the pool after reaching the set vacuum degree, and introduces the carrier gas, and repeats this process 3 times;

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

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 accurately 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-area 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;

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

8. 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, the X-axis and Y-axis deflect at high speed, the laser beam enters the field lens and is focused onto the working surface. The "Z" axis automatically adjusts the focus at high speed and accurately to perform three-dimensional laser ablation of the sample.

9. 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 enter the mass spectrometer for element detection to form a high-quality elemental plane map of the sample.

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 compartment door automatically closes;

11. The wafer manipulator takes the wafer out of the wafer rack and puts it into the clamp of the fully automatic grinding and polishing system for fixation;

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

13. After polishing, the wafer robot moves the wafer to the wafer rack;

14. Repeat steps 2 to 13 in the method until the analysis task is completed;

15. Take out the wafer samples, put them into the sample box, mark them, and store them in the designated location;

16. Turn off the carrier gas and system devices according to standard procedures;

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

In some other applications, technicians in this field 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.

In this embodiment, since Raman spectroscopy detection 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.

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

In addition to wafer samples, for some solid samples whose structures include chemical bonds with low heat tolerance, such as metal organic framework compounds (MOFs), their surface chemical structure may also change due to the energy of the focus point when subjected to laser ablation. Therefore, the mechanical grinding and polishing of this embodiment can also avoid the interference of the above-mentioned thermal change effect on the detection results. In addition, if the sample is made into the same specifications as the wafer, it can be compatible with the wafer-related handling device to simplify the process. For solid samples of biological samples and molecular crystals, since their intermolecular forces can absorb the energy of the laser focus, grinding and polishing are generally not required.

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.

The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims (11)

A three-dimensional laser ablation mass spectrometer, characterized by comprising: 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. The three-dimensional laser ablation mass spectrometer according to claim 1 is characterized in that it also includes a wafer robot, which is used for loading and unloading wafers. The three-dimensional laser ablation mass spectrometer according to claim 1 is characterized in that 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; 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. The three-dimensional laser ablation mass spectrometer according to claim 1 is 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 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. A combined detection system, characterized in that it comprises: a 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. The combined detection system according to claim 5 is 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. A detection method for a three-dimensional laser ablation mass spectrometer, characterized in that the three-dimensional laser ablation mass spectrometer as described in any one of claims 1 to 4 is used, and the sample is a wafer. The detection method according to claim 7, characterized in that it comprises the following steps: 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. A detection method for a combined detection system, characterized by using the combined detection system as described in claim 5 or 6. The detection method according to claim 9, characterized in that it comprises the following steps: 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. The detection method according to claim 9 is characterized in that the sample is a wafer or a metal organic framework compound or a new semiconductor material.