Optical alignment method for eliminating time drift

Abstract

The application provides a light school calibration detection method for eliminating time drift. The sample to be detected and a calibration piece are placed on a stage; the calibration piece is subjected to calibration detection, excitation light and detection light are simultaneously irradiated on the calibration piece, and a measurement value I A of a reflection signal of the calibration piece to the detection light detected under current conditions is obtained B ; the sample to be detected is subjected to calibration detection, excitation light and detection light are simultaneously irradiated on the sample to be detected, and a measurement value I A of a reflection signal of the sample to be detected to the detection light detected under current conditions is obtained B ; according to the measurement values I A , I B and a standard value I S of a reflection signal of the calibration piece to the detection light detected under standard conditions, a true value I R of a reflection signal of the sample to be detected to the detection light under standard conditions is calculated. The application adds a calibration piece and corresponding calibration detection steps, so that the characteristic physical quantity of the sample to be detected is corrected, and the measurement result is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor detection, in particular to a photoelectric calibration detection method for eliminating time drift. BACKGROUND

[0002] The yield of a semiconductor front-end preparation process is a focus of attention and improvement in the semiconductor field, and is a prerequisite for whether the performance of a processed chip meets the standard, so monitoring the front-end preparation process is crucial.

[0003] For example, in ion implantation preparation process, the detection method of ion implantation conditions (such as ion implantation doping concentration, ion implantation energy, ion implantation angle, etc. Process parameters) of the prepared semiconductor multilayer material has four probe electrical detection method and light modulation detection method. Among them, the light modulation signal has high sensitivity to semiconductor characteristics, and the detection method has the characteristics of non-contact and non-destructive detection, which can be used to monitor the lattice defects, doping concentration and uniformity inside the semiconductor, so it has become an important tool for semiconductor front-end detection.

[0004] The light modulation signal is generally excited and detected by a pump-probe optical method, and the signal strength depends on the temperature and humidity of the equipment and other environmental influences, mainly due to changes in optical conditions (such as laser intensity, spot size and center distance of excitation and detection) and the influence of stage stability. Therefore, the light modulation signal obtained by repeated testing of a single wafer cannot distinguish whether it is affected by the time drift of the detection equipment or the physical characteristics of the wafer have changed, or the light modulation signal obtained by testing multiple wafers in order 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, thus reducing the accuracy of the signal for yield detection, and the detection ability of the detection equipment cannot meet the requirements. SUMMARY

[0005] The purpose of the present application is to provide a photoelectric calibration detection method for eliminating time drift, by adding a calibration wafer in the existing detection equipment, and adjusting the detection method accordingly, and then correcting the data, to restore the light modulation signal that can truly reflect the internal characteristics of the semiconductor.

[0006] To achieve the above purpose, the present application realizes by the following technical scheme:

[0007] A photoelectric calibration detection method for eliminating time drift, comprising:

[0008] Placing the sample to be tested and the calibration wafer on the stage;

[0009] performing calibration detection on the calibration sheet: moving the stage to position the calibration sheet at a position to be detected, and simultaneously irradiating the calibration sheet with the excitation light and the probe light, and obtaining a measured value I of a reflection signal of the probe light detected from the calibration sheet under the current condition A ;

[0010] performing calibration detection on the calibration sheet: moving the stage to position the calibration sheet at a position to be detected, and simultaneously irradiating the calibration sheet with the excitation light and the probe light, and obtaining a measured value I of a reflection signal of the probe light detected from the calibration sheet under the current condition B ;

[0011] calculating a true value I of a reflection signal of the probe light from the sample under the standard condition according to the measured value I A , the measured value I B , and a standard value I S of a reflection signal of the probe light from the calibration sheet detected under the standard condition R .

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

[0013] Optionally, the method further comprises:

[0014] adjusting the position of the focal plane to the surface to be detected of the calibration sheet by an automatic focusing system after moving the stage to position the calibration sheet at a position to be detected; and

[0015] adjusting the position of the focal plane to the surface to be detected of the sample to be detected by an automatic focusing system after moving the stage to position the sample to be detected at a position to be detected.

[0016] Optionally, the method further comprises:

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

[0018] adjusting the position of the focal plane to the surface to be detected of the calibration sheet by an automatic focusing system after moving the stage to position the calibration sheet at a position to be detected; and

[0019] keeping the focal plane of the automatic focusing system unchanged after moving the stage to position the sample to be detected at a position to be detected.

[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 measured;

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

[0023] After moving the stage to the position where the sample to be measured is to be measured, the focal plane of the automatic focusing system is kept unchanged.

[0024] Optionally, after the calibration detection of the calibration sheet is performed, a correction coefficient of the stage is determined according to the measured value IA and the standard value IS, and if the absolute value of the correction coefficient is less than or equal to a preset value, the calibration detection of the sample to be measured 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 comprises 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 of the probe light greater than or equal to 0.2.

[0028] Optionally, the metal material comprises platinum, gold, titanium and aluminum.

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

[0030] The calibration sheet and the corresponding calibration detection step are added, so that the correction of the characteristic physical quantity of the sample to be measured is realized, and the measurement result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the present application, the drawings required to be used in the description will be briefly introduced as follows. Obviously, the drawings in the following description are one embodiment of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings:

[0032] Figure 1 The structural diagram of the stage for implementing the method of the present application is shown in the figure;

[0033] Figure 2 The flow chart of the optical calibration detection method for eliminating time drift provided by one embodiment of the present application is shown in the figure;

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

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

[0036] The scheme proposed by the present application will be further described in detail below in combination with the drawings and specific embodiments. The advantages and features of the present application will be more apparent according to the following description. It should be noted that the drawings are very simplified and all use non-precise proportions, only for the purpose of facilitating and clearly assisting the description of the embodiments of the present application.

[0037] The present application provides a method for eliminating time drift in optical calibration detection, which performs calibration detection on both a calibration sheet and a sample to be measured, and corrects the measurement result of the sample to be measured according to the measurement result of the calibration sheet, so as to make the measurement result of the sample to be measured more accurate.

[0038] For the convenience of understanding, first, a machine for implementing the method for eliminating time drift in optical calibration detection of the present application is introduced. As shown in Figure 1 the machine includes: a stage 10 for placing a sample B to be measured and a calibration sheet A, the stage 10 is movable along X, Y and Z axes, and is used for measuring the calibration sheet A and scanning and measuring each position of the sample B to be measured; a probe light source 11 for emitting probe light; a first dichroic mirror 12, the probe light is reflected by the first dichroic mirror 12 and then vertically incident on the surface of the sample B to be measured or the calibration sheet A; an excitation light source 13 for emitting excitation light, the excitation light is transmitted by the first dichroic mirror 12 and then vertically incident on the surface of the sample B to be measured or the calibration sheet A; a polarization beam splitter 14 arranged between the probe light source 11 and the first dichroic mirror 12, the probe light emitted by the probe light source 11 is transmitted by the polarization beam splitter 14 and then incident on the first dichroic mirror 12, and the reflection signal of the probe light is reflected by the first dichroic mirror 12 and then incident on the polarization beam splitter 14; a detector 15 arranged on the reflection path of the polarization beam splitter 14, for receiving the reflection signal of the probe light; an autofocus system 16 for adjusting the position of the focal plane to the measured surface of the calibration sheet A and adjusting the position of the focal plane to the measured surface of the sample B to be measured.

[0039] The calibration sheet A is added to the stage 10 to calibrate the measurement result of the sample B to be measured, which is a wafer. The calibration sheet A can at least satisfy the condition that the optical performance is not affected by the external environment. The calibration sheet A can be a single-layer structure or a multi-layer structure. The single-layer structure of the calibration sheet A is made of metal material, and the optical property is more stable than that of semiconductor material. The multi-layer structure of the calibration sheet A at least includes a metal film layer playing a main role, and an oxide layer is arranged on the upper surface and / or the lower surface of the metal film layer. The metal film layer is made of metal material. It can be understood that the reflectivity of metal material to light of different wavelengths is different, and the detection light wavelength used for detecting a certain wafer is fixed. In order to improve the intensity of the detection light received by the detector, the metal material with high reflectivity to the detection light (for example, the reflectivity to the detection light is greater than or equal to 0.2) is preferred, such as platinum, gold, titanium, aluminum, etc.

[0040] The stage can further include a phase-locked amplifier 17 connected with the excitation light source 13 and the detector 15 respectively, for modulating the excitation light emitted by the excitation light source 13 and demodulating the signal received by the detector 15 to obtain the modulated reflected signal. By modulating the excitation light by the phase-locked amplifier 17, the excitation light becomes modulated light and periodically excites the detection sample, so that the signal received by the detector 15 also changes periodically, realizing the demodulation and amplification of the reflected signal of the detection light.

[0041] The stage further includes a half-wave plate 18 and a 1 / 4 wave plate 19. The detection light passes through the half-wave plate 18 to change the polarization state to S-direction linear polarization, so as to be transmitted through the polarization beam splitting crystal 14, and then passes through the 1 / 4 wave plate to become circularly polarized light. The circularly polarized light is reflected by the calibration sheet A or the sample B to be measured again, and then passes through the 1 / 4 wave plate 19 to become P-direction linear polarization. At this time, the P-direction linear polarization is reflected by the polarization beam splitting crystal 14 to the detector 15.

[0042] The stage further includes a mirror 20 arranged 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 mirror 20 and then enters the first dichroic mirror 12.

[0043] The stage further includes a first shutter 21 and a second shutter 22 for controlling the transmission of the detection light and the excitation light along the optical path, respectively.

[0044] The stage further includes a second dichroic mirror 23 and an objective lens 24 arranged 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 table further comprises an image acquisition module, specifically, the image acquisition module comprises 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 different wavelength from the excitation light and the probe light, first transmits through the beam splitter 26, and then is reflected by the third dichroic mirror 27 to the surface of the sample B to be measured or the calibration piece A, for providing illumination for the detection area of the sample B to be measured or the calibration piece A; the reflected light of the illumination light is reflected back to the beam splitter 26 again through the third dichroic mirror 27, and is reflected by the beam splitter 26 and then received by the camera 28. Since the point light source 25 is not a laser light source, it will not affect the sample B to be measured 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 probe light, and will be reflected by the third dichroic mirror 27, while the excitation light and the probe light can transmit through the third dichroic mirror 27, so that the above-mentioned image acquisition module can work independently and does not affect the detection system.

[0046] Next, a kind of optical calibration detection method for eliminating time drift provided by an embodiment of the present application can be realized by the machine table as shown in Figure 1 As shown in Figure 2 Comprise the following steps:

[0047] Step S1: placing the sample to be measured and the calibration piece on the stage.

[0048] In one implementation (based on prior art), the calibration piece A and the sample B to be measured can be directly placed on the stage 10, and when the calibration piece A is detected in step S2, the position of the focal plane needs to be adjusted to the surface to be measured of the calibration piece A by the automatic focusing system 16, and when the sample B to be measured is detected in step S3, the position of the focal plane needs to be adjusted to the surface to be measured of the sample B to be measured by the automatic focusing system 16, that is, the calibration piece A and the sample B to be measured 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, the surface to be measured of the sample B to be measured and the calibration piece A can be placed on the stage 10 by some settings, so that the surfaces to be measured of the two are at the same height, and then in step S2, the position of the focal plane is adjusted to the surface to be measured of the calibration piece by the automatic focusing system 16, and in step S3, only the focal plane of the automatic focusing system 16 needs to be kept unchanged, without the need for focusing operation again.

[0050] It can be understood that if the calibration piece A and the to-be-measured surface of the to-be-measured sample B are not at the same height, the calibration piece A and the to-be-measured sample B need to be focused respectively by the automatic focusing system 16 in the subsequent calibration detection, which may introduce errors. Therefore, the to-be-measured surfaces of the two are located at the same height in advance, and then the automatic focusing system 16 only needs to focus the calibration piece A once in the subsequent process, thereby eliminating the error.

[0051] Specifically, one way is to first adjust the to-be-measured surface of the calibration piece A and the to-be-measured surface of the to-be-measured sample B to be at the same height after the to-be-measured sample B and the calibration piece A are placed on the stage 10 in step S1. Then, the position of the focal plane is adjusted to the to-be-measured surface of the calibration piece A by the automatic focusing system 16 after the calibration piece A is moved to the to-be-measured position by the stage 10 in step S2. The focal plane of the automatic focusing system 16 is kept unchanged after the to-be-measured sample B is moved to the to-be-measured position by the stage 10 in step S3.

[0052] It should be noted that the thicknesses of the calibration piece A and the to-be-measured sample B may be different, and the characteristics may also be different. For example, the calibration piece A is a three-layer structure, including oxide layers located at the top and bottom and a metal film layer located in the middle, and the to-be-measured surface is the upper surface of the metal film layer. The to-be-measured surface of the to-be-measured sample B is the upper surface. If the thicknesses of the calibration piece A and the to-be-measured sample B are consistent, the heights of the to-be-measured surfaces of the two are inconsistent when they are placed on the stage 10. Therefore, the heights of the two need to be adjusted so that the to-be-measured surfaces are at the same height. For example, the height of the calibration piece A is adjusted, and a gasket is added below the calibration piece A.

[0053] Another way is to adjust the thickness of the calibration piece A to be the same as the thickness of the to-be-measured sample B when the calibration piece A is prepared. Thus, the to-be-measured surfaces of the two are naturally at the same height after the to-be-measured sample B and the calibration piece A are placed on the stage 10 in step S1. Then, the position of the focal plane is adjusted to the to-be-measured surface of the calibration piece A by the automatic focusing system 16 after the calibration piece A is moved to the to-be-measured position by the stage 10 in step S2. The focal plane of the automatic focusing system 16 is kept unchanged after the to-be-measured sample B is moved to the to-be-measured position by the stage 10 in step S3.

[0054] In combination Figure 1 As shown, the excitation light source 13 and the detection light source 11 are selected as continuous lasers, which always emit light after being turned on. Before formal detection, the first shutter 21 and the second shutter 22 are kept closed, and the phase-locked amplifier 17 drives the excitation light source 13 to make the laser emitted by the excitation light source 13 become a laser carrying frequency information, which is called excitation light. At this time, the detector 15 has no detection signal.

[0055] Step S2: calibration detection of the calibration sheet: moving the stage to move the calibration sheet to the position to be detected, and simultaneously irradiating the calibration sheet with the excitation light and the probe light, and obtaining the measurement value I of the reflection signal of the probe light detected by the calibration sheet under the current condition A .

[0056] After the calibration sheet A and the sample B to be detected are placed in step S1, the calibration sheet A is first detected. The stage 10 moves in the XY plane to move the calibration sheet A to the position to be detected, and the position of the focal plane is adjusted to the surface to be detected of the calibration sheet A by the automatic focusing system 16, and then the first shutter 21 and the second shutter 22 are opened simultaneously, so that the excitation light emitted by the excitation light source 13 is reflected by the mirror 20, transmitted through the first dichroic mirror 12 and the objective lens 20 to excite the calibration sheet A, and at the same time, the probe light emitted by the probe light source 11 is reflected by the first dichroic mirror 12 and transmitted through the objective lens 20 to probe the calibration sheet A. The reflection signal of the probe light returns along the original light path and is reflected by the polarization beam splitting crystal 14 to the detector 15. The detector 15 is connected with the lock-in amplifier 17, and the reflection signal received by the detector 15 is recorded and processed by the lock-in amplifier 17. At this time, the lock-in amplifier 17 continuously outputs the light modulation reflection signal of the calibration sheet A, that is, the measurement value I of the reflection signal of the probe light detected by the calibration sheet A under the current condition is obtained A .

[0057] In an implementation mode, after the calibration detection of the calibration sheet A in step S2, the correction coefficient S of the stage can be determined according to the measurement value I A and the standard value I S If the absolute value of the correction coefficient is less than or equal to a preset value (for example, 1%), the calibration detection of the sample B to be detected is performed again in step S3, otherwise, it is considered that the stage is unstable, and adjustment is required before it can be used again.

[0058] Step S3: calibration detection of the calibration sheet: moving the stage to move the calibration sheet to the position to be detected, and simultaneously irradiating the calibration sheet with the excitation light and the probe light, and obtaining the measurement value I of the reflection signal of the probe light detected by the calibration sheet under the current condition 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. If the test surface of the sample B is not at the same height as the test surface of the calibration piece A, the position of the focal plane needs to be adjusted to the test surface of the sample B by the autofocus system 16. If the test surface of the sample B is at the same height as the test surface of the calibration piece A, the focal plane of the autofocus system 16 is kept unchanged, and the test surface of the sample B is also located at the position of the focal plane, so that the test conditions of the sample B and the calibration piece A are the same. Then, the first shutter 21 and the second shutter 22 are opened, causing the excitation light source 13 to be reflected by the mirror 20, transmitted through the first dichroic mirror 12 and the objective lens 20, and then excite the sample B to be tested. Simultaneously, the probe light emitted by the probe light source 11 is reflected by the first dichroic mirror 12, transmitted through the objective lens 20, and then probes the sample B to be tested. The reflected signal of the probe light returns along the original optical path and is reflected by the polarization beam splitter crystal 14 to the detector 15. The reflected signal received by the detector 15 is recorded and processed by the lock-in amplifier 17. At this time, the lock-in amplifier 17 continuously outputs the light-modulated reflection signal of the sample B to be tested, thus obtaining the measured value I of the reflection signal of the sample B to the probe light under the current conditions. B .

[0060] Close the first shutter 11 and the second shutter 22 to complete the calibration test, and then perform step S4 for data processing.

[0061] Step S4: Based on the measured value I A I B and the standard value I of the reflection signal of the probe light from the calibration plate detected under standard conditions. S Calculate the true value I of the reflected signal of the test sample to the probe light under standard conditions. R .

[0062] After demodulation by the lock-in amplifier 17, the change in light intensity of the reflected probe light under the action of the modulated laser is obtained. Since the characteristic physical quantities of the calibration plate A and the test sample B represented by the light intensity value are affected by the environment, but since the test interval between the two is short, they can be approximated as being measured under the same environmental conditions at the same time.

[0063] Changes in environmental conditions themselves do not alter the characteristic physical quantities of the test sample, but they do change the optical modulation signal that reflects these characteristic physical quantities. Therefore, detector 15 is used to first record the measured value I of the optical modulation reflection signal of calibration piece A. A To determine the correction coefficient S, the measured value I of the light modulation reflection signal of the sample B is then used. B To restore the true value of the characteristic physical quantity I of the sample B to be tested. R .

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

[0065] Test sample Standard condition test result Actual condition test result Calibration sheet Standard value I S ]] Light modulated reflection signal I of the calibration patch A ]] Test sample Real value I R ]]> Light modulated 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 factor S. Thus, by the proportional relationship, real values I R of each position can be obtained in real time during the scanning measurement of each position of the to-be-measured sample B.

[0067] In summary, the present application adds a calibration sheet and corresponding calibration detection steps, thereby realizing the correction of the characteristic physical quantity of the to-be-measured sample, and making the measurement result more accurate.

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

Claims

1. An optical calibration and detection method for eliminating time drift, characterized in that, include: The sample to be tested and the calibration plate are placed on the stage. The optical performance of the calibration plate is not affected by the external environment. The sample to be tested and the calibration plate are calibrated and tested under approximately the same environmental conditions. The calibration plate is calibrated and tested as follows: the stage is moved to the position to be tested, and the excitation light and probe light are simultaneously applied to the calibration plate. The measured value I of the reflection signal of the calibration plate to the probe light under the current conditions is obtained. A ; The sample to be tested is calibrated and tested by moving the stage to the test position, illuminating the sample simultaneously with excitation and probe light, and acquiring the measured value I of the reflection signal of the sample to the probe 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 probe light from the calibration plate detected under standard conditions. S Calculate the true value I of the reflected signal of the test sample to the probe light under standard conditions. R I A I B I S I R The following proportional relationship must be satisfied: (I A -I S ) / I S =(I B -I R ) / I R .

2. The optical calibration and detection method for eliminating time drift as described in claim 1, characterized in that, Also includes: After the moving stage moves the calibration piece to the test position, the position of the focal plane is adjusted to the test surface of the calibration piece by the automatic focusing system; as well as After the moving stage moves the sample to the test position, the position of the focal plane is adjusted to the test surface of the sample by the automatic focusing system.

3. The optical calibration and detection method for eliminating time drift as described in claim 1, characterized in that, Also includes: After placing the sample to be tested and the calibration strip on the stage, adjust the test surface of the calibration strip and the test surface of the sample to be tested to be at the same height. After the moving stage moves the calibration piece to the test position, the position of the focal plane is adjusted to the test surface of the calibration piece by the automatic focusing system; as well as After moving the stage to bring the sample to the test position, the focal plane of the autofocus system remains unchanged.

4. The optical calibration and detection method for eliminating time drift as described in 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 the moving stage moves the calibration piece to the test position, the position of the focal plane is adjusted to the test surface of the calibration piece by the automatic focusing system; as well as After moving the stage to bring the sample to the test position, the focal plane of the autofocus system remains unchanged.

5. The optical calibration and detection method for eliminating time drift as described in claim 1, characterized in that, After calibrating and testing the calibration piece, based on the measured value I A and the standard value I S Determine the correction coefficient of the instrument. If the absolute value of the correction coefficient is less than or equal to the preset value, then perform calibration and testing on the sample to be tested.

6. The optical calibration and detection method for eliminating time drift as described in claim 1, characterized in that, The calibration strip has a single-layer structure and is made of metallic material.

7. The optical calibration and detection method for eliminating time drift as described in claim 1, characterized in that, The calibration sheet has a multi-layer structure and includes a metal film layer made of a metallic material and an oxide layer located on the upper and / or lower surface of the metal film layer.

8. The optical calibration detection method for eliminating time drift as described in claim 6 or 7, characterized in that, The reflectivity of the metallic material to the probe light is greater than or equal to 0.

2.

9. The optical calibration and detection method for eliminating time drift as described in claim 8, characterized in that, The metallic materials include platinum, gold, titanium, and aluminum.

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