Optical calibration detection method for eliminating time drift

Abstract

The invention provides an optical calibration detection method for eliminating time drift. Placing a to-be-tested sample and a calibration sheet on a carrying table; carrying out calibration detection on the calibration sheet, enabling the excitation light and the detection light to irradiate the calibration sheet at the same time, and obtaining a measured value IA of a reflection signal of the calibration sheet to the detection light detected under the current condition; performing calibration detection on the to-be-detected sample: irradiating the to-be-detected sample with the exciting light and the detection light at the same time, and obtaining a measured value IB of a reflected signal of the to-be-detected sample to the detection light detected under the current condition; and according to the measurement values IA and IB and a standard value IS of a reflection signal of the calibration sheet to the detection light detected under the standard condition, calculating a true value IR of the reflection signal of the sample to be detected to the detection light under the standard condition. According to the invention, the calibration sheet and the corresponding calibration detection steps are added, so that the characteristic physical quantity of the to-be-detected sample is corrected, and the measurement result is more accurate.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor detection technology, and in particular to an optical calibration detection method for eliminating time drift. Background Art

[0002] The yield rate of the semiconductor front-end manufacturing process is the focus of attention and improvement in the semiconductor field. It is also the prerequisite for whether the performance of processed chips meets the standards. Therefore, monitoring of the front-end manufacturing process is crucial.

[0003] For example, in the ion implantation preparation process, the current detection methods for the ion implantation conditions (such as ion implantation doping concentration, ion implantation energy, ion implantation angle and other process parameters) of the semiconductor multilayer materials prepared by this process include the four-probe electrical detection method and the optical modulation detection method. Among them, the optical modulation signal has a high sensitivity to the semiconductor characteristics, and the detection method has the characteristics of non-contact and non-destructive testing, which can be used to monitor the lattice defects, doping concentration and uniformity inside the semiconductor, and thus has become an important tool for semiconductor front-end detection.

[0004] Optical modulation signals are generally excited and detected by pump-probe optical methods. The signal strength depends on environmental influences such as the temperature and humidity of the equipment. This is mainly due to changes in optical conditions caused by the environment (such as laser intensity, spot size, and center distance of excitation and detection) and the influence of stage stability. Therefore, the optical modulation signal obtained by repeated testing of a single wafer cannot distinguish whether it is the effect of the time drift of the detection equipment or the change in the physical characteristics of the wafer itself, or the optical modulation signal obtained by testing multiple wafers in sequence cannot distinguish whether it is the difference in ion implantation conditions between wafers or the signal fluctuation caused by the time drift of the detection equipment. Therefore, the accuracy of the signal for yield detection is reduced, and the detection capability of the detection equipment cannot meet the requirements. Summary of the invention

[0005] The purpose of the present invention is to provide an optical calibration detection method for eliminating time drift, by adding a calibration piece to the existing detection equipment, adjusting the detection method accordingly, and then performing data correction, thereby restoring an optical modulation signal that can truly reflect the internal characteristics of the semiconductor.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] An optical calibration detection method for eliminating time drift, comprising:

[0008] Place the sample to be tested and the calibration sheet on the stage;

[0009] Calibrate and test the calibration sheet: move the stage to move the calibration sheet to the position to be tested, make the excitation light and the detection light illuminate the calibration sheet at the same time, and obtain the measured value I of the reflection signal of the calibration sheet to the detection light detected under the current conditions A ;

[0010] Calibrate and test the sample to be tested: move the stage to move the sample to be tested to the position to be tested, make the excitation light and the detection light illuminate the sample to be tested at the same time, and obtain the measured value I of the reflection signal of the sample to be tested to the detection light under the current conditions. B ;

[0011] According to the measured value I A ,I B and the standard value I of the reflection signal of the detection light of the calibration piece detected under standard conditions S , calculate the true value I of the reflection signal of the detection light of the sample to be tested under standard conditions R .

[0012] Optionally, I A ,I B ,IS,I R Satisfies the following proportional relationship: (I A -I S ) / I S =(I B -I R ) / I R .

[0013] Optionally, the method further comprises:

[0014] After moving the stage to move the calibration sheet to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration sheet by an automatic focusing system; and

[0015] After the stage is moved to move the sample to be tested to the position to be tested, the position of the focal plane is adjusted to the surface to be tested of the sample to be tested by the automatic focusing system.

[0016] Optionally, the method further comprises:

[0017] After placing the sample to be tested and the calibration sheet on the stage, adjusting the surface to be tested of the calibration sheet and the surface to be tested of the sample to be tested to be at the same height;

[0018] After moving the stage to move the calibration sheet to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration sheet by an automatic focusing system; and

[0019] After the stage is moved to move the sample to be tested to the position to be tested, the focal plane of the automatic focusing system is kept unchanged.

[0020] Optionally, the method further comprises:

[0021] When preparing the calibration sheet, the thickness of the calibration sheet is adjusted to be the same as the thickness of the sample to be tested;

[0022] After moving the stage to move the calibration sheet to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration sheet by an automatic focusing system; and

[0023] After the stage is moved to move the sample to be tested to the position to be tested, the focal plane of the automatic focusing system is kept unchanged.

[0024] Optionally, after the calibration plate is calibrated and tested, the correction coefficient of the machine is determined according to the measured value IA and the standard value IS. If the absolute value of the correction coefficient is less than or equal to a preset value, the calibration test of the sample to be tested is performed again.

[0025] Optionally, the calibration sheet is a single-layer structure and is made of metal material.

[0026] Optionally, the calibration sheet is a multi-layer structure, and includes a metal film layer made of metal material and an oxide layer located on the upper surface and / or lower surface of the metal film layer.

[0027] Optionally, the metal film layer has a reflectivity greater than or equal to 0.2 for the detection light.

[0028] Optionally, the metal material includes platinum, gold, titanium, or aluminum.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] A new calibration sheet and corresponding calibration test steps are added to achieve the correction of the characteristic physical quantities of the sample to be measured, making the measurement results more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0032] Figure 1 A structural diagram of a machine for implementing the method provided by the present invention;

[0033] Figure 2 A flow chart of an optical calibration detection method for eliminating time drift provided by one embodiment of the present invention;

[0034] The reference numerals in the accompanying drawings of the specification are as follows:

[0035] Stage 10, calibration plate A, sample to be measured B, detection light source 11, first dichroic mirror 12, excitation light source 13, polarization beam splitting crystal 14, detector 15, automatic focusing system 16, lock-in amplifier 17, half-wave plate 18, 1 / 4 wave plate 19, reflector 20, first shutter 21, second shutter 22, second dichroic mirror 23, objective lens 24, point light source 25, beam splitter 26, third dichroic mirror 27, camera 28. DETAILED DESCRIPTION

[0036] The scheme proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0037] The present invention provides an optical calibration detection method for eliminating time drift, wherein calibration detection is performed on both a calibration sheet and a sample to be tested, and the measurement result of the sample to be tested is corrected according to the measurement result of the calibration sheet, so that the measurement result of the sample to be tested is more accurate.

[0038] For ease of understanding, the machine used to implement the optical calibration detection method for eliminating time drift of the present invention is first introduced. Figure 1 As shown, the machine comprises: a stage 10, for placing a sample B to be tested and a calibration piece A, the stage 10 can move along the X, Y, and Z axes to measure the calibration piece A, and scan and measure each position of the sample B to be tested; a detection light source 11, for emitting detection light; a first dichroic mirror 12, the detection light is reflected by the first dichroic mirror 12 and vertically incident on the surface of the sample B to be tested or the calibration piece A; an excitation light source 13, for emitting excitation light, the excitation light is transmitted by the first dichroic mirror 12 and vertically incident on the surface of the sample B to be tested or the calibration piece A; a polarization beam splitter crystal 14, The body 14 is arranged between the detection light source 11 and the first dichroic mirror 12. The detection light emitted by the detection light source 11 is transmitted through the polarization beam splitting crystal 14 and then incident on the first dichroic mirror 12. The reflection signal of the detection light is reflected by the first dichroic mirror 12 and then incident on the polarization beam splitting crystal 14. The detector 15 is arranged on the reflection path of the polarization beam splitting crystal 14 and is used to receive the reflection signal of the detection light. The automatic focusing system 16 is used to adjust the position of the focal plane to the surface to be measured of the calibration piece A, and to adjust the position of the focal plane to the surface to be measured of the sample B to be measured.

[0039] By adding a calibration piece A on the stage 10, it is used to calibrate the measurement result of the sample B to be tested, and the sample to be tested is a wafer. The calibration piece A can at least meet the condition that the optical performance is not affected by the external environment. The calibration piece A can be a single-layer structure or a multi-layer structure. Among them, the calibration piece A with a single-layer structure is made of metal material, which has more stable optical properties than semiconductor materials. The calibration piece A with a multi-layer structure at least includes a metal film layer that plays a major role, and an oxide layer is arranged on the upper surface and / or the lower surface of the metal film layer, and the metal film layer is made of metal material. It can be understood that the reflectivity of metal materials to light of different wavelengths is different, and for a certain wafer, the wavelength of the detection light used for its detection is fixed. In order to increase the intensity of the detection light received by the detector, it is preferred to have a metal material with a high reflectivity to the detection light (for example, the reflectivity to the detection light is greater than or equal to 0.2), such as platinum, gold, titanium, aluminum, etc.

[0040] The machine may further include: a phase-locked amplifier 17, which is connected to the excitation light source 13 and the detector 15, respectively, and is used to modulate the excitation light emitted by the excitation light source 13, and demodulate the signal received by the detector 15, to obtain a modulated reflection signal. By adding the phase-locked amplifier 17 to modulate the excitation light, it becomes modulated light and periodically excites the detection sample, so that the signal received by the detector 15 also presents a periodically changing state, thereby realizing demodulation and amplification of the reflection signal of the detection light.

[0041] The machine also includes: a half-wave plate 18 and a 1 / 4 wave plate 19. The detection light changes its polarization state through the half-wave plate 18 to become linearly polarized light in the S direction, so that it can be transmitted through the polarization beam splitting crystal 14, and then changes into circularly polarized light through the 1 / 4 wave plate, and is reflected by the sample B to be tested or the calibration plate A and changes into linearly polarized light in the P direction through the 1 / 4 wave plate 19 again, and is reflected by the polarization beam splitting crystal 14 to the detector 15.

[0042] The machine further includes a reflector 20 disposed between the excitation light source 13 and the first dichroic mirror 12 . The excitation light emitted by the excitation light source 13 is reflected by the reflector 20 and then incident on the first dichroic mirror 12 .

[0043] The machine also includes a first shutter 21 and a second shutter 22, which are respectively used to control the detection light and the excitation light to be transmitted along the optical path.

[0044] The machine further includes a second dichroic mirror 23 and an objective lens 24, which are disposed between the first dichroic mirror 12 and the stage 10. The automatic focusing system 16 cooperates with the second dichroic mirror 23 and the objective lens 24 to adjust the position of the focal plane.

[0045] The machine also includes an image acquisition module. Specifically, the image acquisition module includes a point light source 25, a beam splitter 26, a second dichroic mirror 27 and a camera 28. The point light source 25 emits an illumination light of a wavelength different from that of the excitation light and the detection light, which is first transmitted through the beam splitter 26 and then reflected by the third dichroic mirror 27 to reach the surface of the sample B to be tested or the calibration piece A, so as to provide illumination for the detection area of ​​the sample B to be tested or the calibration piece A. The reflected light of the illumination light is again reflected back to the beam splitter 26 by the third dichroic mirror 27, and is then received by the camera 28 after being reflected by the beam splitter 26. Since the point light source 25 is not a laser light source, it will not affect the sample B to be tested or the calibration piece A. At the same time, the wavelength of the point light source 25 is different from that of the excitation light and the detection light, and will be reflected by the third dichroic mirror 27, while the excitation light and the detection light can be transmitted through the third dichroic mirror 27, so the above-mentioned image acquisition module can work independently and will not affect the detection system.

[0046] Next, an optical calibration detection method for eliminating time drift provided by an embodiment of the present invention can be used as follows: Figure 1 The machine shown is implemented as Figure 2 As shown, the following steps are included:

[0047] Step S1: Place the sample to be tested and the calibration sheet on the stage.

[0048] In one implementation method (based on the prior art), the calibration piece A and the sample B to be tested can be directly placed on the stage 10. When the calibration piece A is detected in step S2, the position of the focal plane needs to be adjusted to the test surface of the calibration piece A through the automatic focusing system 16. When the sample B to be tested is detected in step S3, the position of the focal plane needs to be adjusted to the test surface of the sample B to be tested through the automatic focusing system 16. That is, the calibration piece A and the sample B to be tested are focused before measurement, so as to improve the measurement accuracy of the calibration piece A and the calibration piece B.

[0049] In other implementations, some settings can be made so that after the sample B to be tested and the calibration piece A are placed on the stage 10, the test surfaces of the two are at the same height. Then, in step S2, the position of the focal plane is adjusted to the test surface of the calibration piece through the automatic focusing system 16. In step S3, it is only necessary to keep the focal plane of the automatic focusing system 16 unchanged, and there is no need to perform the focusing operation again.

[0050] It is understandable that if the calibration sheet A and the test surface of the sample B are not at the same height, then during the subsequent calibration test, the calibration sheet A and the sample B need to be focused separately through the automatic focusing system 16, which may introduce errors. Therefore, the test surfaces of the two are placed at the same height in advance, so that the automatic focusing system 16 only needs to focus the calibration sheet A once subsequently, thereby eliminating this error.

[0051] Specifically, one method is that after placing the sample B to be tested and the calibration piece A on the stage 10 in step S1, first adjust the test surface of the calibration piece A and the test surface of the sample B to be tested to be at the same height, then in step S2, move the stage 10 to make the calibration piece A to the test position, adjust the position of the focal plane to the test surface of the calibration piece A through the automatic focusing system 16, and after moving the stage 10 to make the sample B to be tested to the test position in step S3, keep the focal plane of the automatic focusing system 16 unchanged.

[0052] It should be noted that the thickness of the calibration sheet A and the sample B to be tested may be different, and the characteristics may also be different. For example, the calibration sheet A is a three-layer structure, including an oxide layer located at the top and bottom and a metal film layer located in the middle. Its surface to be tested is the upper surface of the metal film layer, and the surface to be tested of the sample B to be tested is the upper surface. If the thickness of the calibration sheet A and the sample B to be tested is the same, the heights of the surfaces to be tested are inconsistent when they are placed on the stage 10. Therefore, it is necessary to adjust the heights of the two so that the surfaces to be tested are at the same height, for example, the height of the calibration sheet A is adjusted, and a gasket is added under the calibration sheet A.

[0053] Another way is, when preparing the calibration piece A, the thickness of the calibration piece A is adjusted to be the same as the thickness of the sample B to be tested, so that after placing the sample B to be tested and the calibration piece A on the stage 10 in step S1, the test surfaces of the two are naturally located at the same height, and then in step S2, after moving the stage 10 to move the calibration piece A to the test position, the position of the focal plane is adjusted to the test surface of the calibration piece A through the automatic focusing system 16, and after moving the stage 10 to move the sample B to the test position in step S3, the focal plane of the automatic focusing system 16 is kept unchanged.

[0054] Combination Figure 1 As shown, the excitation light source 13 and the detection light source 11 are continuous lasers, which keep emitting light after being turned on. Before the formal detection, the first shutter 21 and the second shutter 22 are both kept closed, and the phase-locked amplifier 17 drives the excitation light source 13, so that the laser it emits becomes a laser carrying frequency information, called excitation light, and at this time, the detector 15 has no detection signal.

[0055] Step S2: Calibrate and test the calibration sheet: Move the stage to move the calibration sheet to the position to be tested, make the excitation light and the detection light illuminate the calibration sheet at the same time, and obtain the measured value I of the reflection signal of the calibration sheet to the detection light detected under the current conditions. A .

[0056] After the calibration piece A and the sample B to be tested are placed in step S1, the calibration piece A is first tested. The stage 10 moves in the XY plane, moves the calibration piece A to the position to be tested, and adjusts the position of the focal plane to the surface to be tested of the calibration piece A through the automatic focusing system 16, and then opens the first shutter 21 and the second shutter 22 at the same time, so that the excitation light emitted by the excitation light source 13 is reflected by the reflector 20 in turn, transmitted through the first dichroic mirror 12 and the objective lens 20, and then excites the calibration piece A. At the same time, the detection light emitted by the detection light source 11 is reflected by the first dichroic mirror 12 and transmitted through the objective lens 20 to detect the calibration piece A. The reflection signal of the detection light returns along the original optical path and is reflected by the polarization beam splitting crystal 14 to the detector 15. The detector 15 is connected to the phase-locked amplifier 17, and the reflection signal received by the detector 15 is recorded and processed by the phase-locked amplifier 17. At this time, the phase-locked amplifier 17 continuously outputs the light modulated reflection signal of the calibration piece A, that is, the measurement value I of the reflection signal of the detection light of the calibration piece A detected under the current conditions is obtained. A .

[0057] In one implementation, after the calibration sheet A is calibrated and tested in step S2, the measured value I A and the standard value I S Determine the correction coefficient S of the machine. If the absolute value of the correction coefficient is less than or equal to a preset value (for example, 1%), then enter step S3 to calibrate the sample B to be tested. Otherwise, the machine is considered unstable and needs to be adjusted before it can be used again.

[0058] Step S3: Calibrate and test the sample to be tested: move the stage to bring the sample to be tested to the position to be tested, make the excitation light and the detection light illuminate the sample to be tested at the same time, and obtain the measured value I of the reflection signal of the sample to be tested to the detection light under the current conditions. B .

[0059] Specifically, the first shutter 21 and the second shutter 22 are closed, and the stage 10 moves in the XY plane to move the sample B to be tested to the test position. At this time, if the test surface of the sample B to be tested and the test surface of the calibration piece A are not at the same height, it is necessary to adjust the position of the focal plane to the test surface of the sample B to be tested through the automatic focusing system 16. If the test surface of the sample B to be tested and the test surface of the calibration piece A are at the same height, the focal plane of the automatic focusing system 16 is kept unchanged, and the test surface of the sample B to be tested is also at the position of the focal plane, so that the test conditions of the sample B to be tested and the calibration piece A are the same. Then, the first shutter 21 and the second shutter 22 are opened, so that the excitation light source 13 is reflected by the reflector 20 in turn, transmitted through the first dichroic mirror 12 and the objective lens 20, and then excites the sample B to be tested. At the same time, the detection light emitted by the detection light source 11 is reflected by the first dichroic mirror 12, and then transmitted through the objective lens 20 to detect the sample B to be tested. The reflection signal of the detection light returns along the original optical path and is reflected by the polarization beam splitting crystal 14 to the detector 15. The reflection signal received by the detector 15 is recorded and processed by the phase-locked amplifier 17. At this time, the phase-locked amplifier 17 continuously outputs the light modulated reflection signal of the sample B to be tested, that is, the measurement value I of the reflection signal of the detection light of the sample B to be tested detected under the current conditions is obtained. B .

[0060] The first shutter 11 and the second shutter 22 are closed to complete the calibration test, and then step S4 is executed to perform data processing.

[0061] Step S4: According to the measured value I A ,I B and the standard value I of the reflection signal of the detection light of the calibration piece detected under standard conditions S , calculate the true value I of the reflection signal of the detection light of the sample to be tested under standard conditions R .

[0062] After demodulation by the phase-locked amplifier 17, what is obtained is the change in the light intensity value of the reflected detection light under the action of the modulated laser. Since the characteristic physical quantities of the calibration piece A and the sample B to be tested represented by the light intensity value will be affected by the environment, but since the test interval between the two is short, it can be approximated that the measurements are performed at the same time and under the same environmental conditions.

[0063] The change of environmental conditions itself does not change the characteristic physical quantity of the test sample, but the change of environmental conditions will change the light modulation signal reflecting the characteristic physical quantity. Therefore, the detector 15 is used to record the measured value I of the light modulation reflection signal of the calibration piece A. A To determine the correction coefficient S, and then according to the measured value I of the light modulated reflection signal of the sample B to be tested B To restore the true value I of the characteristic physical quantity of the sample B to be tested R .

[0064] Specifically, the actual situation is shown in the following table:

[0065] Test samples Standard test results Actual condition test results Calibration Sheet <![CDATA[Standard value I S > <![CDATA[Optical modulation reflection signal I of the calibration sheet A > Samples to be tested <![CDATA[True value I R > <![CDATA[Optical modulation reflection signal I of the sample to be measured B >

[0066] The above measurement results have a proportional relationship: (I A -I S ) / I S =(I B -I R ) / I R =Correction coefficient S. Thus, through this proportional relationship, real-time calibration can be performed during the scanning measurement of each position of the sample B to be measured, and the true value I of each position can be obtained. R .

[0067] In summary, the present invention realizes the correction of characteristic physical quantities of the sample to be measured by adding a calibration sheet and corresponding calibration detection steps, so as to make the measurement result more accurate.

[0068] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. An optical calibration detection method for eliminating time drift, characterized in that: include: Place the sample to be tested and the calibration sheet on the stage; Calibrate and test the calibration sheet: move the stage to move the calibration sheet to the position to be tested, make the excitation light and the detection light illuminate the calibration sheet at the same time, and obtain the measured value I of the reflection signal of the calibration sheet to the detection light detected under the current conditions A ; Calibrate and test the sample to be tested: move the stage to move the sample to be tested to the test position, make the excitation light and the detection light illuminate the sample to be tested at the same time, and obtain the measured value I of the reflection signal of the sample to be tested to the detection light under the current conditions. B ; According to the measured value I A ,I B and the standard value I of the reflection signal of the detection light of the calibration piece detected under standard conditions S , calculate the true value I of the reflection signal of the detection light of the sample to be tested under standard conditions R .

2. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: I A , I B , I S , I R Proportional system less than full foot: (I A -I S ) / I S = (I B -I R ) / I R .

3. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: Also includes: After moving the stage to move the calibration piece to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration piece by an automatic focusing system; as well as After the stage is moved to move the sample to be tested to the position to be tested, the position of the focal plane is adjusted to the surface to be tested of the sample to be tested by the automatic focusing system.

4. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: Also includes: After placing the sample to be tested and the calibration sheet on the stage, adjusting the surface to be tested of the calibration sheet and the surface to be tested of the sample to be tested to be at the same height; After moving the stage to move the calibration piece to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration piece by an automatic focusing system; as well as After the stage is moved to move the sample to be tested to the position to be tested, the focal plane of the automatic focusing system is kept unchanged.

5. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: Also includes: When preparing the calibration sheet, the thickness of the calibration sheet is adjusted to be the same as the thickness of the sample to be tested; After moving the stage to move the calibration piece to the position to be measured, the position of the focal plane is adjusted to the surface to be measured of the calibration piece by an automatic focusing system; as well as After the stage is moved to move the sample to be tested to the position to be tested, the focal plane of the automatic focusing system is kept unchanged.

6. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: After the calibration sheet is calibrated and tested, according to the measured value I A and the standard value I S The correction coefficient of the machine is determined. If the absolute value of the correction coefficient is less than or equal to a preset value, the calibration test of the sample to be tested is performed again.

7. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: The calibration sheet is a single-layer structure and is made of metal material.

8. The optical calibration detection method for eliminating time drift according to claim 1, characterized in that: The calibration sheet is a multi-layer structure, and includes a metal film layer made of metal material and an oxide layer located on the upper surface and / or lower surface of the metal film layer.

9. The optical calibration detection method for eliminating time drift according to claim 6 or 7, characterized in that: The reflectivity of the metal material to the detection light is greater than or equal to 0.

2.

10. The optical calibration detection method for eliminating time drift according to claim 8, characterized in that: The metal materials include platinum, gold, titanium and aluminum.

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