CN113552112A - Method and system for detecting laser focusing plane inside silicon carbide - Google Patents
Method and system for detecting laser focusing plane inside silicon carbide Download PDFInfo
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Abstract
The application discloses a method and a system for detecting a laser focusing plane in silicon carbide. The system comprises a displacement table and a picosecond pulse laser and confocal Raman generator coupled with a light beam, wherein a damage is formed inside silicon carbide to be detected through picosecond laser focusing, and a Raman peak position of a standard silicon carbide Raman spectrum is obtained; adjusting the position of the silicon carbide to be detected on the Z axis to obtain Raman signals of a plurality of Raman sampling points; comparing the Raman peak position of the sampling point with the Raman peak position of the standard silicon carbide Raman spectrum to obtain the Raman peak displacement of the sampling point; and further calculating by using a double-axis model to obtain the Raman residual stress of each Raman sampling point, and determining the position of a real focusing plane according to the position of the corresponding sampling point when the Raman residual stress is maximum. The method and the device can realize in-situ detection of the Raman residual stress in a short time in a small range, quickly measure the position of the actual focusing plane of the picosecond pulse laser, and calculate and set the error of the focusing plane.
Description
Technical Field
The invention relates to the field of nondestructive testing, in particular to a method and a system for testing a laser focusing plane in silicon carbide.
Background
The wide bandgap silicon carbide is a third-generation high-performance semiconductor developed after single crystal silicon, and is widely applied to the fields of new energy, communication, illumination and the like. As silicon carbide substrates move toward wider and thinner substrates, the wafer dicing process becomes an important step in increasing the yield of the substrates. Conventional diamond wire saw cutting techniques result in significant material loss and surface roughness when cutting larger and thinner wafers.
The ultrafast pulse laser can be used for finely processing materials, has the advantages of short pulse width, high peak energy, small spot area, no pollution and the like, and has relatively mature processes for cutting wafers by nanosecond pulse laser and femtosecond pulse laser at the present stage. Picosecond pulsed lasers have the advantage of being relatively inexpensive compared to the expensive cost of femtosecond pulsed lasers and the huge thermal stress of nanosecond pulsed lasers.
However, the existing picosecond pulse laser has the problem that the focusing plane has errors in the process of processing the silicon carbide.
Disclosure of Invention
Based on this, the embodiment of the application provides a method and a system for detecting a laser focusing plane inside silicon carbide, which can assist a picosecond laser to adjust a self-focusing plane and reduce a processing error by utilizing the maximum relation of raman residual stress in a damaged area.
In a first aspect, a method for detecting a laser focusing plane inside silicon carbide is provided, which includes:
detecting the silicon carbide to be detected to obtain the Raman peak position omega of the standard silicon carbide Raman spectrum0；
Forming damage to the interior of the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected;
adjusting the position of the silicon carbide to be detected on a Z axis by fixing the position of the silicon carbide to be detected on an X-Y plane to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions; the Raman sampling point is in the damage area, the X-Y plane is parallel to a focusing plane of picosecond laser and confocal Raman, and the Z axis is perpendicular to the focusing plane of picosecond laser and confocal Raman;
determining a Raman peak position ω of a Raman spectrum of silicon carbide at each Raman sampling point thereiniAnd standard ofRaman peak position omega of silicon carbide Raman spectrum0Obtaining the Raman peak displacement delta omega of each Raman sampling pointiWherein i is 1,2 … n;
according to the Raman peak displacement delta omega of each Raman sampling pointiAnd calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model, and determining a real focusing plane according to the corresponding Raman sampling point when the Raman residual stress is maximum.
Optionally, the method further comprises:
adjusting the position of the silicon carbide to be detected on an X axis or a Y axis, and enabling picosecond laser focusing to form continuous damage on the interior of the silicon carbide to be detected to obtain a new damaged area, wherein the X axis and the Y axis are parallel to an internal focusing plane of a Raman spectrometer;
and re-determining the focusing plane according to the new damaged area of the silicon carbide to be detected.
Optionally, the obtaining of the damaged region of the to-be-detected silicon carbide by forming a damage to the inside of the to-be-detected silicon carbide through picosecond laser focusing includes:
and focusing picosecond laser on a focusing plane set in the silicon carbide to be detected under the condition of ensuring the silicon carbide to be fixed by presetting the peak energy and the pulse width of a picosecond pulse laser, and damaging the interior of the silicon carbide to be detected to obtain a damaged area of the silicon carbide to be detected.
Optionally, determining a raman peak position ω of the raman spectrum of the silicon carbide for each raman sampling point thereiniRaman peak position ω of Raman spectrum with standard silicon carbide0Obtaining the Raman peak displacement delta omega of each Raman sampling pointiThe method comprises the following steps:
the Raman peak position omega of the Raman spectrum of the silicon carbide of each Raman sampling point is measurediSubtracting the Raman peak position omega of the standard silicon carbide Raman spectrum0Obtaining the Raman peak displacement delta omega of each Raman sampling pointi。
Optionally, the Raman peak shift Δ ω according to each Raman sampling pointiBy passingCalculating the Raman residual stress of each Raman sampling point by using a double-axis model, wherein the Raman residual stress of each Raman sampling point is obtained according to a first formula, and the first formula comprises the following steps:
wherein σ (MPa) represents raman residual stress, Δ ω represents raman peak shift of a currently calculated raman sampling point, and a' represents phonon deformation potential energy.
Optionally, the determining the position of the real focal plane according to the raman sampling point corresponding to the maximum raman residual stress includes:
and carrying out spatial labeling on each obtained Raman sampling point to obtain a Raman residual stress spatial distribution diagram, wherein the position with the maximum Raman residual stress represents the position of a real focusing plane.
Optionally, the adjusting the position of the silicon carbide to be detected on the Z axis includes:
the silicon carbide to be detected is arranged on the displacement table, and the position of the displacement table in the Z-axis direction is adjusted by fixing the position of the displacement table in the X-Y horizontal plane, so that the position of the silicon carbide to be detected in the Z direction is adjusted.
Optionally, the adjusting the position of the silicon carbide to be detected on the Z axis further includes:
adjusting the position of the damaged area in the silicon carbide to be detected by adjusting the positions of the silicon carbide to be detected on the displacement table on the X axis and the Y axis; the X-axis and the Y-axis are parallel to the focal plane of the picosecond laser and the confocal Raman.
In a second aspect, there is provided a silicon carbide internal laser focusing plane inspection system, the system comprising:
the displacement table is used for driving the silicon carbide to be detected placed on the displacement table to move through self displacement;
the device comprises a beam-coupled picosecond pulse laser and confocal Raman generator, a standard silicon carbide Raman spectrum analyzer and a confocal Raman spectrum analyzer, wherein the picosecond pulse laser and the confocal Raman generator are used for detecting silicon carbide to be detected to obtain a Raman peak position of the standard silicon carbide Raman spectrum;
forming damage to the interior of the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected;
adjusting the position of the silicon carbide to be detected on a Z axis by fixing the position of the silicon carbide to be detected on an X-Y plane to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions;
determining the Raman peak position of the silicon carbide Raman spectrum of each Raman sampling point, and obtaining the Raman peak displacement of each Raman sampling point with the Raman peak position of the standard silicon carbide Raman spectrum;
and calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model according to the Raman peak displacement of each Raman sampling point, and determining a real focusing plane according to the Raman sampling point corresponding to the maximum Raman residual stress.
Optionally, the beam-coupled picosecond pulse laser and confocal raman generator comprises a picosecond pulse laser, a dichroic beamsplitter and a raman spectrometer, wherein:
the picosecond pulse laser is used for emitting focused picosecond laser to the silicon carbide to be detected;
the dichroic beam splitter is used for reflecting the picosecond pulse laser and transmitting the Raman laser to couple the reflected pulse laser with the transmitted Raman laser beam;
the Raman spectrometer specifically comprises:
the confocal Raman generator is used for emitting focused Raman laser to the silicon carbide to be detected;
an objective lens for focusing the picosecond laser or the Raman laser;
the confocal pinhole is used for filtering stray signals outside a focusing plane;
the spectrometer is used for separating Raman signals with different wavelengths;
the CCD detector is used for outputting a silicon carbide Raman spectrum according to the intensity of the Raman signal;
and the spectrum analysis module is used for carrying out peak position extraction and Raman residual stress calculation according to the silicon carbide Raman spectrum.
The technical scheme provided by the embodiment of the application has the beneficial effects that:
the detection method based on the confocal Raman spectrometer avoids physical damage to the silicon carbide material, can realize nondestructive in-situ detection of the position of a focusing plane of picosecond pulse laser in the silicon carbide, assists a laser to adjust the focusing plane, and realizes real-time error correction in the processing process; in addition, the average detection time of the confocal Raman per cubic micron is 0.2s, so that the Raman residual stress can be detected in a short time in a small range, the position of the actual focusing plane of picosecond pulse laser can be rapidly measured, and the error of the focusing plane can be calculated and set.
Drawings
Fig. 1 is a flowchart of a method for detecting a laser focusing plane inside silicon carbide according to an embodiment of the present disclosure;
FIG. 2 is a picosecond pulsed laser and confocal Raman generator providing beam coupling according to embodiments of the present application;
FIG. 3 is a schematic illustration of a process provided in an embodiment of the present application;
FIG. 4 is a Raman spectrum of silicon carbide provided by an embodiment of the present application;
fig. 5 provides a partial schematic view of raman sampling according to an embodiment of the present application;
FIG. 6 is a graph showing the shift of the Raman peak (i.e., the E2(TO) peak) provided by the examples of the present application;
fig. 7 is a schematic diagram of a raman residual stress distribution according to an embodiment of the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
The embodiment of the application is based on that the pulsed laser can be accompanied with the diffusion of high-energy particles, the evaporation and solidification of materials in the process of removing the materials, and a large amount of residual stress is left in the materials. The principle that the molecular structure deformation can be reflected through the Raman peak displacement is adopted as a bridge for connecting stress and strain, the residual stress of Raman signal Raman sampling points in the silicon carbide is calculated by using a double-shaft model, and the maximum relation of the Raman residual stress at the damage position of a laser focusing plane is used for assisting a picosecond laser to adjust a self-focusing plane, so that the processing error is reduced.
Referring to fig. 1, a flow chart of a method for detecting a laser focusing plane inside silicon carbide according to an embodiment of the present application is shown, where the method may include the following steps:
In actual measurement, the raman spectra of different varieties of silicon carbide with different purities are different, so that different silicon carbide raman spectra are possessed.
As shown in fig. 2, in the embodiment of the present application, a picosecond pulse laser and a confocal raman generator coupled by a light beam are used to detect silicon carbide to be detected, where the picosecond pulse laser and the confocal raman generator coupled by a light beam include a picosecond pulse laser, a dichroic beam splitter, and a raman spectrometer.
Specifically, a confocal raman laser light source in the raman spectrometer emits focused raman laser to the silicon carbide to be detected to excite a raman signal of the silicon carbide to be detected, so that a standard silicon carbide raman spectrum is obtained.
And 102, forming damage inside the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected.
In an embodiment of the application, the peak energy and the pulse width of a picosecond pulse laser in a confocal raman spectrometer are set, and picosecond laser is focused on a focus plane set in silicon carbide to be detected under the condition that silicon carbide is ensured to be fixed, so that damage is formed in the silicon carbide to be detected.
Specifically, as shown in fig. 3, the displacement stage is stationary, the picosecond pulse laser is turned on, the peak energy and pulse width of the laser are set, and under the condition that the silicon carbide is fixed, the picosecond laser is focused on a focus plane set in the silicon carbide to damage the silicon carbide material, and the picosecond pulse laser is turned off.
Setting the diameter or width of confocal pinhole or slit to be less than or equal to 200 μm to ensure the Z-direction spatial resolution of confocal Raman spectrometer, selecting 40-60 times long working distance objective lens with numerical aperture NA of 0.5, and setting the spectral scanning range to be 600cm-1-1000cm-1The position of the E2(TO) peak of the silicon carbide is collected, as shown in fig. 4, the raman peaks such as E2(TO) and a1(LO) are included, and in the embodiment of the present invention, the E2(TO) peak is uniformly used as the raman peak for implementing the invention.
And 103, adjusting the position of the silicon carbide to be detected on the Z axis to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions.
Wherein the Z-axis is perpendicular to the focal plane of the raman spectrometer.
Specifically, the position of the silicon carbide to be detected on an X-Y plane is fixed, the depth of a set picosecond pulse laser focusing plane is set to be Z0, due to the fact that crystal lattices of a damage center are damaged, a raman signal is not a silicon carbide raman signal, a displacement table can move 2 μm in the X direction to avoid the damage center, a damage region in the application comprises a region where picosecond pulse laser is focused and a region which is smaller than or equal to 3 μm near the damage center, and then a light spot of a confocal raman spectrometer is set to be focused on the position Z0.
In this embodiment, as shown in fig. 5, the displacement stage is moved 10um in the negative Z direction, at this time, the light spot of the confocal raman spectrometer is focused at a position where Z is 10um, raman signal sampling is started, the displacement stage is moved up by 2um each time until Z is-8 um, 10 points are sampled, and the raman laser is turned off.
104, determining the Raman peak position omega of the Raman spectrum of the silicon carbide of each Raman sampling pointiRaman peak position ω of Raman spectrum with standard silicon carbide0Obtaining the Raman peak displacement delta omega of each Raman sampling pointiWhere i is 1,2 … n.
In the embodiment of the application, as shown in fig. 6, the positions ω where the E2(TO) peaks of raman sampling points at different spatial positions are located are obtainediSubtract the position ω of the standard E2(TO) peak0Then obtaining the Raman peak displacement delta omega of each Raman sampling point in the spacei(cm-1)；
105, according to the Raman peak displacement delta omega of each Raman sampling pointiAnd calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model, and determining the position of the real focusing plane according to the Raman sampling point corresponding to the maximum Raman residual stress.
In one embodiment of the present application, the raman peak shift Δ ω according to each raman sampling pointiAnd calculating the Raman residual stress of each Raman sampling point through a double-axis model, wherein the Raman residual stress of each Raman sampling point is obtained according to a first formula, and the first formula comprises the following steps:
wherein σ (MPa) represents raman residual stress, Δ ω represents raman peak shift of a currently calculated raman sampling point, and a' represents phonon deformation potential energy.
In order to realize Raman in-situ sampling, the picosecond laser beam and the confocal Raman laser beam are coupled by the same confocal objective lens group, and the picosecond laser and the Raman laser alternately work.
Determining the position of a real focusing plane according to a Raman sampling point corresponding to the maximum Raman residual stress, wherein the method comprises the following steps:
and as shown in fig. 7, performing spatial labeling on each obtained raman sampling point to obtain a raman residual stress spatial distribution diagram, wherein the position where the raman residual stress is the maximum represents the position of a real focusing plane.
In an optional embodiment of the present application, after the foregoing steps are implemented, the method further includes:
and 106, adjusting the position of the silicon carbide to be detected on the X axis or the Y axis, enabling picosecond laser to be focused to form continuous damage inside the silicon carbide to be detected, and re-determining the focusing plane according to the new damage area of the silicon carbide to be detected.
Wherein the X-axis and the Y-axis are parallel to the focusing plane of the confocal Raman spectrometer
Specifically, after the picosecond laser focusing plane is calibrated, the picosecond pulse laser is opened, and the displacement table moves at the speed of 100mm/s along the x direction, so that continuous damage is formed in the silicon carbide. And after a period of time, stopping the movement of the displacement table, turning off the laser, measuring and correcting the error of the focusing plane of the picosecond pulse laser, and repeating the steps 102 to 105 until the processing is finished.
The method of the invention has the following advantages:
the detection method based on the confocal Raman spectrometer avoids physical damage to the silicon carbide material, can realize nondestructive in-situ detection of the position of a focusing plane of picosecond pulse laser in the silicon carbide, assists a laser to adjust the focusing plane, and realizes real-time error correction in the processing process; in addition, the average detection time of the confocal Raman per cubic micron is 0.2s, so that the Raman residual stress can be detected in a short time in a small range, the position of the actual focusing plane of picosecond pulse laser can be rapidly measured, and the error of the focusing plane can be calculated and set.
The system for detecting the laser focusing plane inside the silicon carbide comprises a picosecond pulse laser and a confocal Raman generator which are used for carrying out light beam coupling, and a movable displacement platform, and specifically comprises:
the displacement table is used for driving the silicon carbide to be detected placed on the displacement table to move through self displacement;
the device comprises a beam-coupled picosecond pulse laser and confocal Raman generator, a standard silicon carbide Raman spectrum analyzer and a confocal Raman spectrum analyzer, wherein the picosecond pulse laser and the confocal Raman generator are used for detecting silicon carbide to be detected to obtain a Raman peak position of the standard silicon carbide Raman spectrum;
forming damage to the interior of the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected;
fixing the position of the silicon carbide to be detected on an X-Y plane, and adjusting the position of the silicon carbide to be detected on a Z axis to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions;
determining the Raman peak position of the silicon carbide Raman spectrum of each Raman sampling point, and obtaining the Raman peak displacement of each Raman sampling point with the Raman peak position of the standard silicon carbide Raman spectrum;
and calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model according to the Raman peak displacement of each Raman sampling point, and determining a real focusing plane according to the Raman sampling point corresponding to the maximum Raman residual stress.
Wherein the beam-coupled picosecond pulse laser and confocal Raman generator comprises a picosecond pulse laser, a dichroic beam splitter and a Raman spectrometer,
the picosecond pulse laser comprises picosecond pulse laser with Nd: YVO4 as a light source, and is used for emitting focused picosecond laser to the silicon carbide to be detected;
a dichroic beam splitter for reflecting the picosecond pulse laser and transmitting the Raman laser;
the Raman spectrometer specifically comprises a confocal Raman laser light source, a confocal pinhole or slit, a spectroscopic spectrometer, a displacement table, an objective lens, a CCD detector and spectral analysis software, wherein the confocal Raman laser light source, the confocal pinhole or slit, the spectroscopic spectrometer, the displacement table, the objective lens, the CCD detector and the spectral analysis software are arranged in the Raman spectrometer
The confocal Raman generator (i.e. a confocal Raman laser light source) is used for emitting focused Raman laser to the silicon carbide to be detected, i.e. determining a focusing plane and exciting a Raman signal of a sample;
an objective lens for focusing picosecond laser light or Raman laser light;
the confocal pinhole, the confocal pinhole or the slit is used as a spatial filter for filtering stray signals out of a focusing plane;
the spectrometer is used for separating Raman signals with different wavelengths;
the CCD detector is used for outputting a silicon carbide Raman spectrum according to the intensity of the Raman signal;
and the spectrum analysis module is used for carrying out peak position extraction and Raman residual stress calculation according to the silicon carbide Raman spectrum.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for detecting a laser focusing plane in silicon carbide is characterized by comprising the following steps:
detecting the silicon carbide to be detected to obtain the Raman peak position omega of the standard silicon carbide Raman spectrum0；
Forming damage to the interior of the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected;
adjusting the position of the silicon carbide to be detected on a Z axis by fixing the position of the silicon carbide to be detected on an X-Y plane to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions; the Raman sampling point is in the damage area, the X-Y plane is parallel to a focusing plane of picosecond laser and confocal Raman, and the Z axis is perpendicular to the focusing plane of picosecond laser and confocal Raman;
determining a Raman peak position ω of a Raman spectrum of silicon carbide at each Raman sampling point thereiniRaman peak position ω of Raman spectrum with standard silicon carbide0Obtaining the Raman peak displacement delta omega of each Raman sampling pointiWherein i is 1,2 … n;
according to the Raman peak position of each Raman sampling pointShift by Δ ωiAnd calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model, and determining a real focusing plane according to the corresponding Raman sampling point when the Raman residual stress is maximum.
2. The method of claim 1, further comprising:
adjusting the position of the silicon carbide to be detected on an X axis or a Y axis, and enabling picosecond laser focusing to form continuous damage on the interior of the silicon carbide to be detected to obtain a new damaged area, wherein the X axis and the Y axis are parallel to an internal focusing plane of a Raman spectrometer;
and re-determining the focusing plane according to the new damaged area of the silicon carbide to be detected.
3. The method according to claim 1, wherein the obtaining of the damaged region of the silicon carbide to be detected by forming damage to the inside of the silicon carbide to be detected through picosecond laser focusing comprises:
and focusing picosecond laser on a focusing plane set in the silicon carbide to be detected under the condition of ensuring the silicon carbide to be fixed by presetting the peak energy and the pulse width of a picosecond pulse laser, and damaging the interior of the silicon carbide to be detected to obtain a damaged area of the silicon carbide to be detected.
4. The method of claim 1, wherein determining the Raman peak position ω of the Raman spectrum of the silicon carbide for each Raman sample point comprises determining the Raman peak position ω of the Raman spectrum of the silicon carbide for each Raman sample pointiRaman peak position ω of Raman spectrum with standard silicon carbide0Obtaining the Raman peak displacement delta omega of each Raman sampling pointiThe method comprises the following steps:
the Raman peak position omega of the Raman spectrum of the silicon carbide of each Raman sampling point is measurediSubtracting the Raman peak position omega of the standard silicon carbide Raman spectrum0Obtaining the Raman peak displacement delta omega of each Raman sampling pointi。
5. The method of claim 1, wherein the Raman peak shift from each Raman sampling point is Δ ωiCalculating the Raman residual stress of each Raman sampling point through a double-axis model,
the method comprises the following steps of obtaining the Raman residual stress of each Raman sampling point according to a first formula, wherein the first formula comprises the following steps:
wherein σ (MPa) represents raman residual stress, Δ ω represents raman peak shift of a currently calculated raman sampling point, and a' represents phonon deformation potential energy.
6. The method of claim 1, wherein determining the true focal plane position from the corresponding raman sample point at which the raman residual stress is maximum comprises:
and carrying out spatial labeling on each obtained Raman sampling point to obtain a Raman residual stress spatial distribution diagram, wherein the position with the maximum Raman residual stress represents the position of a real focusing plane.
7. The method of claim 1, wherein the adjusting the position of the silicon carbide to be detected in the Z-axis comprises:
the silicon carbide to be detected is arranged on the displacement table, and the position of the displacement table in the Z-axis direction is adjusted by fixing the position of the displacement table on the X-Y horizontal plane, so that the position of the silicon carbide to be detected on the Z axis is adjusted.
8. The method of claim 7, wherein the adjusting the position of the silicon carbide to be detected in the Z-axis further comprises:
adjusting the position of the damaged area in the silicon carbide to be detected by adjusting the positions of the silicon carbide to be detected on the displacement table on the X axis and the Y axis; the X-axis and the Y-axis are parallel to the focal plane of the picosecond laser and the confocal Raman.
9. A silicon carbide internal laser focal plane inspection system, the system comprising:
the displacement table is used for driving the silicon carbide to be detected placed on the displacement table to move through self displacement;
the device comprises a beam-coupled picosecond pulse laser and confocal Raman generator, a standard silicon carbide Raman spectrum analyzer and a confocal Raman spectrum analyzer, wherein the picosecond pulse laser and the confocal Raman generator are used for detecting silicon carbide to be detected to obtain a Raman peak position of the standard silicon carbide Raman spectrum;
forming damage to the interior of the silicon carbide to be detected through picosecond laser focusing to obtain a damaged area of the silicon carbide to be detected;
adjusting the position of the silicon carbide to be detected on a Z axis by fixing the position of the silicon carbide to be detected on an X-Y plane to obtain Raman signals of a plurality of Raman sampling points of the silicon carbide to be detected on different Z axis positions;
determining the Raman peak position of the silicon carbide Raman spectrum of each Raman sampling point, and obtaining the Raman peak displacement of each Raman sampling point with the Raman peak position of the standard silicon carbide Raman spectrum;
and calculating to obtain the Raman residual stress of each Raman sampling point through a double-axis model according to the Raman peak displacement of each Raman sampling point, and determining a real focusing plane according to the Raman sampling point corresponding to the maximum Raman residual stress.
10. The system of claim 9, wherein the beam-coupled picosecond pulse laser and confocal raman generator comprises a picosecond pulse laser, a dichroic beam splitter, and a raman spectrometer, wherein:
the picosecond pulse laser is used for emitting focused picosecond laser to the silicon carbide to be detected;
the dichroic beam splitter is used for reflecting the picosecond pulse laser and transmitting the Raman laser;
the Raman spectrometer specifically comprises:
the confocal Raman generator is used for emitting focused Raman laser to the silicon carbide to be detected;
an objective lens for focusing the picosecond laser or the Raman laser;
the confocal pinhole is used for filtering stray signals outside a focusing plane;
the spectrometer is used for separating Raman signals with different wavelengths;
the CCD detector is used for outputting a silicon carbide Raman spectrum according to the intensity of the Raman signal;
and the spectrum analysis module is used for carrying out peak position extraction and Raman residual stress calculation according to the silicon carbide Raman spectrum.
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