A wafer defect detection device and a detection method

Abstract

The present invention provides a wafer defect detection device and a detection method. The detection device includes: a light source, which includes a detection light source and an excitation light source. The detection light source emits detection incident light, and the excitation light source emits excitation incident light; a first beam splitting device, a first beam splitting device is arranged in the incident optical path of the detection incident light, and the first beam splitting device is used to split the detection incident light emitted by the detection light source into a first detection light and a second detection light; the second detection light coincides with the incident optical path of the excitation light source and is incident on the wafer at 0°; a first signal receiving system, a first signal receiving system is arranged in the outgoing optical path of the first detection light, and is used to receive the detection second harmonic signal emitted by the wafer under the action of the first detection light; a second signal receiving system, a second signal receiving system is arranged in the outgoing optical path of the second detection light, and is used to receive the signal emitted by the wafer under the action of the second detection light. The detection device of the present invention improves the detection efficiency and the reliability of the detection result.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and particularly to a wafer defect detection device and a detection method. Background Art

[0002] The wafer processing process includes multiple processes, such as lithography, etching, deposition, etching, etc. Each process may introduce defects, such as residual photoresist layer, uneven etching, inconsistent etching depth, etc. These processing defects will directly affect the performance and reliability of semiconductor devices. Therefore, it is crucial to detect defects on wafers.

[0003] Currently, the methods for detecting defects on wafers are mainly divided into two categories: destructive and non-destructive. The destructive detection methods play a very important role in the analysis of surface damage of optical materials and semiconductor crystal materials. However, these methods not only cause irreversible damage to the samples, but also have disadvantages such as time-consuming and strong dependence on experience.

[0004] Second harmonic signal detection is a new type of non-destructive detection method. Second harmonic signal detection is a technique for characterizing and diagnosing wafer defects by exciting, collecting, and analyzing the second harmonic signals generated at the wafer interface and surface. The principle is that there are defects inside and at the interfaces of various film layers in the wafer. After the laser reaches the substrate, it excites the electron transition in the substrate, which is captured by some defects, and dynamically generates second harmonic signals. This method can detect many defects related to electrical characteristics, such as interface states and accumulated charges; defects related to film quality, such as fixed charges, defect charges, mobile charges, lattice defects, etc.; and surface charge distributions related to surface quality.

[0005] The application of second harmonic signal detection in wafer defect detection has not been widely promoted. In practical applications, it is found that when the detection results are abnormal, it is very difficult to quickly determine what kind of defects in the wafer cause the abnormality. In addition, due to possible abnormalities in the detection device itself resulting in deviations, a single detection method cannot be completely reliable and cannot meet the requirements of fast and accurate detection under the new process technology. Summary of the Invention

[0006] In view of the above defects of the prior art, the present invention provides a wafer defect detection device. The wafer defect detection device divides the detection incident light emitted by a detection light source into a first detection light and a second detection light. A first signal receiving system receives the detection second harmonic signal emitted by the action of the first detection light, and a second signal receiving system receives the signal emitted by the action of the second detection light. The signals obtained by the first signal receiving system and the second signal receiving system are compared and verified with each other to obtain the wafer defect detection result, overcoming the problem that a single detection method cannot be mutually verified, improving the detection efficiency and detection accuracy, and ensuring the reliability of the detection result. For this reason, the present invention also provides a wafer defect detection method

[0007] In a first aspect of the present invention, there is provided a wafer defect detection device, comprising:

[0008] A light source, the light source includes a detection light source and an excitation light source. The detection light source emits detection incident light, and the excitation light source emits excitation incident light;

[0009] A first beam splitting device, a first beam splitting device is provided in the incident light path of the detection incident light. The first beam splitting device is used to divide the detection incident light emitted by the detection light source into a first detection light and a second detection light; the second detection light coincides with the incident light path of the excitation light source and is incident on the wafer at 0°.

[0010] A first signal receiving system, a first signal receiving system is provided in the outgoing light path of the first detection light, and is used to receive the detection second harmonic signal emitted by the wafer under the action of the first detection light;

[0011] A second signal receiving system, a second signal receiving system is provided in the outgoing light path of the second detection light, and is used to receive the signal emitted by the wafer under the action of the second detection light.

[0012] As a preferred embodiment, the wafer defect detection device further includes a lock-in amplifier. One end of the lock-in amplifier is connected to the excitation light source and is used to preprocess the excitation light emitted by the excitation light source into modulated light; the other end of the lock-in amplifier is connected to the second signal receiving system and is used to demodulate the signal received by the second signal receiving system. The modulated light is modulated light with a time-varying intensity characteristic.

[0013] As a preferred embodiment, the first signal receiving system includes a polarization beam splitting device. The polarization beam splitting device is provided on the outgoing light path of the first detection light and is used to separate the generated detection second harmonic signal into a P-polarized signal and an S-polarized signal. The first signal receiving system further includes a P-signal receiving end and an S-signal receiving end, which respectively receive the P-polarized signal and the S-polarized signal.

[0014] As a preferred embodiment, a first polarization element is provided on the incident optical path of the first detection light for adjusting the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the S signal receiving end is used to reduce the noise of the second harmonic signal received by the P signal receiving end, or,

[0015] When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P signal receiving end is used to reduce the noise of the second harmonic signal received by the S signal receiving end.

[0016] As a preferred embodiment, the incident angle adjustment range of the first detection light is 15° - 75°.

[0017] As a more preferred embodiment, the incident angle of the first detection light is 45°.

[0018] As a preferred embodiment, the photon energy of the detection light source is lower than the band gap of any material in the wafer to be measured.

[0019] As a preferred embodiment, the power of the excitation light source is adjustable.

[0020] As a more preferred embodiment, the power adjustment range of the excitation light source is 5 mw - 1 w.

[0021] As a preferred embodiment, the wafer defect detection device further includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system for processing the signals received by the first signal receiving system and the second signal receiving system.

[0022] As a preferred embodiment, the wafer defect detection device further includes a wafer stage, an input system and a display system;

[0023] The wafer is placed on the wafer stage and is translated and / or rotated on the horizontal plane along with the wafer stage;

[0024] The input system is used to receive the input information of the user in human-computer interaction;

[0025] The display system is used to display the output information of the wafer defect detection device in human-computer interaction.

[0026] As a more preferred embodiment, the wafer defect detection device further includes an autofocus system for adjusting the focal plane of the excitation light source.

[0027] In the second aspect of the present invention, a wafer defect detection device is provided, including:

[0028] A light source, the light source including a detection light source and an excitation light source, the detection light source emitting detection incident light, and the excitation light source emitting excitation incident light;

[0029] A first beam splitting device, a first beam splitting device is arranged in the incident light path of the detection incident light, and is used for splitting the detection incident light emitted by the detection light source into a first detection light and a second detection light; the first detection light does not coincide with the incident light path of the excitation light source;

[0030] A third beam splitting device, a third beam splitting device is arranged in the incident light path of the excitation light source, and is used for splitting the excitation light source into a first excitation light and a second excitation light, the excitation positions of the first excitation light and the second excitation light on the sample to be measured do not coincide; the second detection light coincides with the incident light path of the second excitation light, and is incident on the wafer at 0°.

[0031] A first signal receiving system, a first signal receiving system is arranged in the outgoing light path of the first detection light, and is used for receiving the detection second harmonic signal emitted by the wafer under the action of the first detection light;

[0032] A second signal receiving system, a second signal receiving system is arranged in the outgoing light path of the second detection light, and is used for receiving the signal emitted by the wafer under the action of the second detection light.

[0033] As a preferred embodiment, the wafer defect detection device further includes a lock-in amplifier, one end of the lock-in amplifier is connected to the excitation light source, and is used for preprocessing the excitation light emitted by the excitation light source into modulated light; the other end of the lock-in amplifier is connected to the second signal receiving system, and is used for demodulating the signal received by the second signal receiving system, and the modulated light is modulated light with a time-varying intensity characteristic.

[0034] As a preferred embodiment, the first signal receiving system includes a polarization beam splitting device, the polarization beam splitting device is arranged on the outgoing light path of the first detection light, and is used for separating the generated detection second harmonic signal into a P polarization signal and an S polarization signal, and the first signal receiving system further includes a P signal receiving end and an S signal receiving end, which respectively receive the P polarization signal and the S polarization signal.

[0035] As a preferred embodiment, a first polarization element is arranged on the incident light path of the first detection light, and is used for adjusting the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the S signal receiving end is used to reduce the noise of the second harmonic signal received by the P signal receiving end, or,

[0036] When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P signal receiving end is used to reduce the noise of the second harmonic signal received by the S signal receiving end.

[0037] As a preferred embodiment, the incident angle adjustment range of the first detection light is 15°-75°

[0038] As a more preferred embodiment, the incident angle of the first detection light is 45°.

[0039] As a preferred embodiment, the photon energy of the detection light source is lower than the band gap width of any material in the wafer to be measured.

[0040] As a more preferred embodiment, the power ratio of the first excitation light to the second excitation light is ≥10:1.

[0041] As a more preferred embodiment, the excitation position interval of the first excitation light and the second excitation light on the wafer to be measured is [200μm, 1mm].

[0042] As a more preferred embodiment, the wafer defect detection device further includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system for processing the signals received by the first signal receiving system and the second signal receiving system.

[0043] As a preferred embodiment, the wafer defect detection device further includes a wafer stage, an input system and a display system;

[0044] The wafer is placed on the wafer stage and is translated and / or rotated on the horizontal plane along with the wafer stage;

[0045] The input system is used to receive the input information of the user in human-computer interaction;

[0046] The display system is used to display the output information of the wafer defect detection device in human-computer interaction.

[0047] As a more preferred embodiment, the wafer defect detection device further includes an autofocus system for adjusting the focal plane of the excitation light source.

[0048] In a third aspect of the present invention, there is provided a wafer defect detection device, including:

[0049] A light source, the light source includes a detection light source and an excitation light source, the detection light source emits detection incident light, the excitation light source emits excitation incident light, and the excitation light source includes a third excitation light and a fourth excitation light;

[0050] A first beam splitter is provided in the incident light path for detecting incident light to split the detection incident light emitted by the detection light source into a first detection light and a second detection light. The incident light paths of the first detection light and the third excitation light do not overlap, and the incident light paths of the second detection light and the fourth excitation light overlap. The second detection light, the third excitation light, and the fourth excitation light all enter the wafer at 0°.

[0051] A first signal receiving system is provided in the exit light path of the first detection light to receive the detected second harmonic signal emitted by the wafer under the action of the first detection light.

[0052] A second signal receiving system is provided in the exit light path of the second detection light to receive the signal emitted by the wafer under the action of the second detection light.

[0053] As a preferred embodiment, the wafer defect detection device further includes a lock-in amplifier. One end of the lock-in amplifier is connected to the excitation light source to preprocess the excitation light emitted by the excitation light source into a modulated light. The other end of the lock-in amplifier is connected to the second signal receiving system to demodulate the signal received by the second signal receiving system. The modulated light is a modulated light with a time-varying intensity characteristic.

[0054] As a preferred embodiment, the first signal receiving system includes a polarization beam splitter. The polarization beam splitter is provided on the exit light path of the first detection light to separate the generated detected second harmonic signal into a P-polarized signal and an S-polarized signal. The first signal receiving system further includes a P-signal receiving end and an S-signal receiving end to receive the P-polarized signal and the S-polarized signal respectively.

[0055] As a preferred embodiment, a first polarization element is provided on the incident light path of the first detection light to adjust the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the S-signal receiving end is used to reduce the noise of the second harmonic signal received by the P-signal receiving end, or

[0056] When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P-signal receiving end is used to reduce the noise of the second harmonic signal received by the S-signal receiving end.

[0057] As a preferred embodiment, the incident angle adjustment range of the first detection light is 15° - 75°.

[0058] As a more preferred embodiment, the incident angle of the first detection light is 45°.

[0059] As a preferred embodiment, the photon energy of the detection light source is lower than the bandgap of any material in the wafer to be measured.

[0060] As a more preferred embodiment, the wafer defect detection device further includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system and is used for processing the signals received by the first signal receiving system and the second signal receiving system.

[0061] As a preferred embodiment, the wafer defect detection device further includes a wafer stage, an input system, and a display system;

[0062] The wafer is placed on the wafer stage and is translated and / or rotated on the horizontal plane along with the wafer stage;

[0063] The input system is used to receive the input information of the user in the human-computer interaction;

[0064] The display system is used to display the output information of the wafer defect detection device in the human-computer interaction.

[0065] As a more preferred embodiment, the wafer defect detection device further includes an autofocus system for adjusting the focal plane of the excitation light source.

[0066] In the fourth aspect of the present invention, there is provided a wafer defect detection method, which applies the above-mentioned wafer defect detection device and includes the following steps:

[0067] S1. Turn on the detection light source, and the first signal receiving system and the second signal receiving system respectively receive the signals excited by the first detection light and the second detection light. At this time, the signals are both constant and in the initial state;

[0068] S2. Keep the detection light source on, and at the same time turn on the excitation light source. The charge distribution of the sample to be measured changes, the temperature at the detection point gradually rises, and the signals received by the first signal receiving system and the second signal receiving system change accordingly, which is the excited state; after reaching the excited state, the sample to be measured undergoes annealing, and the signal received by the second signal receiving system gradually decays to a stable state; when the charge distribution of the sample to be measured reaches a new dynamic equilibrium and the temperature at the detection point tends to be stable, the signal received by the first signal receiving system also tends to be stable; process the signals received by the first signal receiving system and the second signal receiving system to obtain the wafer defect detection result.

[0069] As a preferred embodiment, the above-mentioned wafer defect detection method further includes:

[0070] S31. After the signal received by the first signal receiving system tends to be stable, keep the detection light source on and turn off the excitation light source at the same time. The captured electrons return to the substrate layer and recombine, and the signal received by the first signal receiving system gradually recovers, which is called the recovery state. When the recovery time is long enough, the signal received by the first signal receiving system recovers to the initial state; process the signal received by the first signal receiving system to obtain the wafer defect detection result.

[0071] As a preferred embodiment, the above wafer defect detection method further includes:

[0072] S32. A step of correcting the reflectivity of the wafer to the second detection light according to the signal value received by the first signal receiving system.

[0073] As a preferred embodiment, the above correction step is:

[0074] S321. Obtain the thickness t of the oxide layer when a specific second harmonic signal is obtained according to the relationship between the second harmonic signal and the thickness t of the oxide layer;

[0075] S322. Substitute the thickness t of the oxide layer into the following formula to obtain the refractive index n2 of the substrate;

[0076]

[0077] where r with oxide is the reflectivity of the wafer to the second detection light when there is an oxide layer; r0 is the reflectivity of the oxide layer surface, r1 is the reflectivity of the oxide layer and substrate interface, n1 is the refractive index of the oxide layer, and n2 is the refractive index of the substrate;

[0078] S323. Substitute the refractive index n2 of the substrate into the following formula to obtain the reflectivity r of the wafer to the second detection light when there is no oxide layer without oxide ;

[0079]

[0080] In the fifth aspect of the present invention, a wafer defect detection method is provided, which uses the above wafer defect detection device, and includes the following steps:

[0081] S1. Turn on the detection light source, and the signals received by the first signal receiving system and the second signal receiving system are both constant, which is the initial state;

[0082] S2. Keep the detection light source on, and at the same time turn on the excitation light source. Adjust the power of the excitation light source to the first excitation value, where the first excitation value is less than the power of the excitation light source required to generate the second harmonic signal. At this time, the temperature at the detection point gradually increases, and the signal received by the second signal receiving system changes accordingly and is in the excited state. After reaching the excited state, the sample to be measured undergoes annealing, and the signal received by the second signal receiving system gradually decays to a stable state.

[0083] S3. Continue to keep the detection light source on, and at the same time adjust the power of the excitation light source to the second excitation value, where the second excitation value is greater than or equal to the power of the excitation light source required to generate the second harmonic signal. At this time, the charge distribution of the sample to be measured changes, and the signal received by the first signal receiving system changes accordingly, which is called the excited state. When the charge distribution of the sample to be measured reaches a new dynamic equilibrium, the signal received by the first signal receiving system tends to be stable.

[0084] S4. Process the signals received by the first signal receiving system and the second signal receiving system to obtain the wafer defect detection result.

[0085] As a preferred embodiment, the first excitation value is ≥5 mw and <50 mw, and the second excitation value is ≥50 mw and ≤1 w.

[0086] As a preferred embodiment, the above wafer defect detection method further includes:

[0087] S5. A step of correcting the reflectivity of the wafer to the second detection light according to the signal value received by the first signal receiving system.

[0088] As a preferred embodiment, the above correction step is:

[0089] S51. According to the relationship between the second harmonic signal and the thickness t of the oxide layer, obtain the thickness t of the oxide layer when a specific second harmonic signal is obtained.

[0090] S52. Substitute the oxide layer thickness t into the following formula to obtain the substrate refractive index n2;

[0091]

[0092] where r with oxide is the reflectivity of the wafer to the second detection light when there is an oxide layer; r0 is the reflectivity of the oxide layer surface, r1 is the reflectivity of the oxide layer and substrate interface, n1 is the oxide layer refractive index, and n2 is the substrate refractive index;

[0093] S53. Substitute the substrate refractive index n2 into the following formula to obtain the reflectivity r of the wafer to the second detection light when there is no oxide layer without oxide ;

[0094]

[0095] A sixth aspect of the present invention provides a computer device, comprising: a processor and a memory;

[0096] The memory is used to store a computer program and transmit the computer program to the processor;

[0097] The processor is used to execute the above-mentioned wafer defect detection method according to the instructions in the computer program.

[0098] A seventh aspect of the present invention provides a computer-readable storage medium, which is used to store a computer program, and the computer program is used to execute the above-mentioned wafer defect detection method.

[0099] An eighth aspect of the present invention provides a product including a computer program. When it runs on a computer device, the computer device executes the above-mentioned wafer defect detection method.

[0100] Compared with the prior art, the present invention has the following beneficial effects:

[0101] (1) For the wafer defect detection device of the present invention, by setting two optical paths, one optical path is incident on the wafer to generate a second harmonic signal, and defects in the wafer, mobile charges, lattice defects, and the uniformity of surface charge distribution are detected; the other optical path is incident on the wafer at 0°, and lattice defects or lattice damage are detected by the change in reflectivity generated by the wafer interface and surface. Since the two have different detection principles, they can avoid interference to a certain extent, and the detection results are mutually verified and compared. Finally, the wafer defect detection result is obtained, which improves the detection efficiency while maintaining the detection accuracy and ensuring the reliability of the detection result.

[0102] (2) For the wafer defect detection device of the present invention, by setting a beam splitting device, a single beam of detection light source is split into two beams of detection light for the detection of wafer defects under two different detection principles, which simplifies the use of components and facilitates the installation and integration of the device; at the same time, it expands the detection scenario and realizes the function of rapid non-destructive detection in the chip manufacturing process.

[0103] The following will further illustrate the concept, specific structure and technical effects of the present invention with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 It is a schematic structural diagram of the wafer defect detection device in Embodiment 1 of the present invention;

[0105] Figure 2It is a signal change curve graph received by the first signal receiving system and the second signal receiving system of the wafer defect detection device in Embodiment 1 of the present invention, where Figure 2 a is the signal change curve graph received by the first signal receiving system, Figure 2 b is the signal change curve graph received by the second signal receiving system;

[0106] Figure 3 It is a schematic structural diagram of the wafer defect detection device in Embodiment 2 of the present invention;

[0107] Figure 4 It is a schematic structural diagram of the wafer defect detection device in Embodiment 3 of the present invention;

[0108] Figure 5 It is a relationship diagram between the second harmonic signal and the oxide layer thickness.

[0109] Among them: detection light source 1, excitation light source 2, first beam splitter 3, first mirror 4, second mirror 5, first collimating lens 6, wafer stage 7, sample to be measured 8, polarization beam splitter 9, P signal receiving end 10, S signal receiving end 11, polarization beam splitting prism 12, fourth beam splitter 13, first dichroic mirror 14, second dichroic mirror 15, second collimating lens 16, lock-in amplifier 17, autofocus sensor 18, observation camera 19, point light source 20, third beam splitter 21, third excitation light 22, fourth excitation light 23, second signal receiving system 24. Specific embodiments

[0110] In order to make the technical means, creative features, achieved purposes and effects of the invention easy to understand, the present invention will be further described below in conjunction with specific illustrations. However, the present invention is not limited to the following implemented cases.

[0111] It should be noted that the structures, proportions, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limited conditions under which the present invention can be implemented. Therefore, they do not have technical essential significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed by the present invention.

[0112] The second harmonic signal detection method is a method for characterizing and diagnosing wafer defects by exciting, collecting, and analyzing the second harmonic signals generated at the wafer interface and surface, and can detect defect charges, mobile charges, lattice defects, surface charge distribution uniformity, etc. However, when using the above method, if the detection result is abnormal, it is impossible to quickly determine whether the abnormal result is only caused by wafer defects or by a malfunction of the detection equipment. In addition, due to the limitation of the detection principle, the second harmonic signal detection method is mainly used for the detection of mobile charges and defect charges. Since the second harmonic detection is also very sensitive to other parameters of the wafer (such as oxide film thickness, interface state charge, etc.), the time-dependent second harmonic detection (abbreviated as second harmonic detection in the present invention) selected in the present invention has a weaker special detection ability for lattice defects than the modulated light detection, and the wafer defect situation cannot be comprehensively and accurately reflected only by the time-dependent second harmonic detection.

[0113] To solve the above technical problems, based on the second harmonic signal detection method, this application adds an optical path, divides the probe light into a first probe light and a second probe light. The first probe light and the excitation light cooperate to generate second harmonic signals for detecting defect charges, mobile charges, lattice defects, and surface charge distribution uniformity; the second probe light is incident at 0°, and the second probe light and the excitation light act together to reflect the change in reflectivity generated at the wafer interface and surface for detecting lattice defects or lattice damage. The two confirm each other to obtain the actual situation of wafer defects.

[0114] Embodiment 1

[0115] Such as Figure 1 , a wafer defect detection device, comprising:

[0116] A light source, the light source includes a probe light source 1 and an excitation light source 2. The probe light source 1 emits a probe incident light, and the excitation light source 2 emits an excitation incident light;

[0117] A first beam splitting device 3 is arranged in the incident optical path of the probe incident light. The first beam splitting device 3 is used to divide the probe incident light emitted by the probe light source 1 into a first probe light and a second probe light; the first beam splitting device 3 here can be a beam splitter. The second probe light coincides with the incident optical path of the excitation light source 2 and is incident on the wafer at 0°;

[0118] A first signal receiving system is arranged in the outgoing optical path of the first probe light. The first signal receiving system is used to receive the detected second harmonic signals emitted by the wafer under the action of the first probe light;

[0119] The first signal receiving system includes a polarization beam splitter 9, a P-signal receiving end 10, and an S-signal receiving end 11. The polarization beam splitter 9 is used to separate the generated detection second harmonic signal into a P-polarized signal and an S-polarized signal; the P-signal receiving end 10 and the S-signal receiving end 11 respectively receive the generated P-polarized signal and S-polarized signal. Both the P-signal receiving end 10 and the S-signal receiving end 11 use a photomultiplier tube (PMT) as a signal receiver.

[0120] A second signal receiving system 24 is provided in the outgoing light path of the second probe light. The second signal receiving system 24 is used to receive the signal emitted by the wafer under the action of the second probe light.

[0121] The light source of the wafer defect detection device includes a detection light source 1 and an excitation light source 2, and both the detection light source 1 and the excitation light source 2 are lasers. "Detection" means that the detection incident light emitted by the detection light source will couple with a structure having non-centrosymmetry to generate a second harmonic signal. Lattice defects (such as interface states, fixed charges, impurity atoms, etc.) are usually coupling centers. Therefore, the generated detection second harmonic signal can be used to characterize the defect charges, mobile charges, lattice defects, surface charge distribution uniformity, etc. of the sample. "Excitation" means that the photons injected by the excitation light source 2 in the detection area are absorbed by electrons, so that the bound electrons in the valence band of the semiconductor layer of the sample to be measured may obtain sufficient energy to be excited into the conduction band of the semiconductor to become free electrons. This electron may be captured by interface state defects or absorb more photons to have enough energy to cross the potential barrier and reach the oxide layer. Finally, a large amount of charge accumulation is formed at the interface or surface of the sample, which is called the charge accumulation process of electrons. This process can be "detected" by the second harmonic. In short, "excitation" can continuously change the internal charge distribution state of the sample to be measured, while "detection" can characterize this continuous change of the sample to be measured. By collecting signals from the sample to be measured for a long time, the wafer defects can be measured and analyzed.

[0122] The detection light source 1 in the wafer defect detection device emits a laser. Under the action of the first beam splitter 3, the emitted laser is divided into a first probe light and a second probe light. The incident light path formed by the first probe light sequentially passes through a first reflector 4, a second reflector 5, and a first collimating lens 6 and is transmitted to the sample 8 to be measured on the wafer stage 7 (in this application, the sample 8 to be measured and the wafer to be measured have the same meaning, both referring to the wafer). The incident light is reflected by the sample 8 to be measured to generate a second harmonic signal. The second harmonic signal is transmitted to the polarization beam splitter 9. The polarization beam splitter 9 is a polarization beam splitter mirror. The polarization beam splitter 9 separates the second harmonic signal into a P-polarized signal and an S-polarized signal, where the P-polarized signal is transmitted to the P-signal receiving end 10, and the S-polarized signal is transmitted to the S-signal receiving end 11.

[0123] The incident optical paths of the second probe light and the excitation light source 2 coincide, and both are incident on the wafer at 0°, that is, perpendicular to the wafer surface. The incident optical path formed by the second probe light is transmitted to the sample 8 to be measured on the wafer stage 7 through the polarization beam splitter prism 12, the fourth beam splitting device 13, the first dichroic mirror 14, the second dichroic mirror 15, and the second collimating lens 16 in sequence. After reflection, the second probe light returns along the original optical path direction, and the generated signal is received by the second signal receiving system 24.

[0124] The settings of the first collimating lens 6 and the second collimating lens 16 enable the optical path to be transmitted more precisely.

[0125] The first probe light obtains a second harmonic signal by detecting the electron accumulation process at the interface or surface of the sample 8 to be measured, and is received by the first signal receiving system. By analyzing the signal changes received by the first signal receiving system, it is possible to judge defect charges, mobile charges, lattice defects, surface charge distribution uniformity, etc. However, due to the limitations of the detection principle, the detection ability of the second harmonic signal detection for lattice defects is relatively weak. The incident optical paths of the second probe light and the excitation light source 2 coincide, and both are incident on the wafer at 0°, that is, perpendicular to the wafer surface. After reflection, the second probe light returns along the original optical path direction. Since the second probe light is reflected by the wafer surface once, its intensity will be reduced by a part. The signal intensity change of the second probe light received by the second signal receiving system 24 reflects the reflectivity change of the wafer, thereby reflecting the lattice defect or lattice damage situation.

[0126] The first probe light and the second probe light are independent optical paths. The first probe light signal received by the first signal receiving system and the second probe light signal received by the second signal receiving system 24 have little influence on each other, and can be judged independently. The two confirm and complement each other, and can comprehensively reflect the wafer defect situation.

[0127] The following is an explanation of the two detection methods in the present invention respectively:

[0128] A. For second harmonic detection: The incident angle range of the first probe light is 15° - 75°. For the convenience of installation, the incident angle of the first probe light is set to 45°. The influence of the incident angle on the second harmonic is mainly reflected in the P polarization component of the second harmonic, because the P component is the vector sum of the incident and perpendicular directions. Therefore, by adjusting the incident angle, certain components in the second-order polarization tensor of the sample 8 to be measured can be quantitatively analyzed.

[0129] Optionally, a first polarization element (not shown in the figure) is provided on the incident light path of the first detection light. Here, the first polarization element is a polarizer, which is used to adjust the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, theoretically, no second harmonic in the S direction will be generated. However, in actual measurement, due to the slight deviation of the polarizer angle or the influence of other factors, the second harmonic signal in the S outgoing light path is not zero. Therefore, the S signal receiving end 11 is used to reduce the noise of the second harmonic signal received by the P signal receiving end 10. When the first polarization element adjusts the polarization direction of the first detection light to S polarization, similarly, at this time, the P signal receiving end 10 is used to reduce the noise of the second harmonic signal received by the S signal receiving end 11.

[0130] B. For modulated light detection: To improve the detection sensitivity and make the weak signal generated by the combined action of the detection light and the excitation light easier to be received by the signal receiving system, modulation technology is often used to preprocess the excitation light into modulated light. Modulated light refers to light in which certain parameters of the light wave, such as amplitude, frequency, phase, polarization state, and duration, change according to certain rules. Modulated light technology refers to the modulation technology of superimposing a signal carrying information on a carrier light wave. Its essence is to modulate one or more of the unit vectors in the polarization direction, amplitude, carrier frequency, and phase. The modulation methods are mainly divided into direct modulation, intracavity modulation, and extracavity modulation. The direct modulation method is to directly control the pump source of the laser (such as controlling the injection current of a semiconductor laser) by an external signal, so as to modulate certain parameters of the laser.

[0131] This application adopts the direct modulation method and uses a lock-in amplifier 17 to preprocess the excitation light so that the excitation light becomes modulated light. The wafer defect detection device includes a lock-in amplifier 17. One end of the lock-in amplifier 17 is connected to the excitation light source 2, which is used to preprocess the excitation light emitted by the excitation light source 2 into modulated light; the other end of the lock-in amplifier 17 is connected to the second signal receiving system 24, which is used to demodulate the signal received by the second signal receiving system 24. The modulated light is a modulated light with a time-varying intensity characteristic.

[0132] The excitation light source 2 can be set to one or two. When it is set to one, the excitation light is excited, and the first signal receiving system and the second signal receiving system 24 respectively receive the signals emitted by the action of the first detection light and the second detection light. When there are two excitation light sources 2, each detection light acts on one excitation light source 2 respectively, so that the signals emitted by the action of the first detection light and the second detection light do not affect or interfere with each other.

[0133] In this embodiment, the excitation light source 2 is set to one, and the first detection light and the second detection light share the excitation light source 2. After being preprocessed by the lock-in amplifier 17, the excitation light source 2 becomes modulated light. When the excitation light source 2 irradiates the detection point, electrons at the detection point absorb energy and undergo transitions. At this time, the charge and electric field distributions inside the wafer change, resulting in a synchronous change in the intensity of the second harmonic signal generated by the first detection light at the interface due to the charge and electric field distributions, and reaching a steady state after a period of time. When the excitation light source 2 is subsequently turned off, the charge distribution at the detection point begins to recover and returns to the initial state after a period of time. At this time, the second harmonic signal generated by the first detection light returns to the initial state. By analyzing the second harmonic signals in the initial state and the steady state, the wafer defects can be analyzed. The excitation light source 2 changes from non-modulated light to modulated light, causing the intensity of the generated second harmonic signal to change periodically, but it will not affect the analysis of the second harmonic signal.

[0134] The incident paths of the second detection light and the excitation light source 2 are the same, and both are incident on the sample to be measured 8 at 0°. Since the excitation light source 2 is modulated light, for the convenience of description, the signal received by the second signal receiving system 24 is called the modulated light signal. The second signal receiving system 24 includes a second signal receiver, and the second signal receiver is a photodiode. The second detection light is incident on the sample to be measured 8 at 0°, and after reflection, the second detection light returns along the original optical path. When there is no excitation light source 2, the signal received by the second signal receiving system 24 is a constant value. After the second detection light is reflected by the wafer once, its intensity will decrease by a part. The intensity of the second detection light received by the second signal receiving system 24 actually reflects the reflectivity R0 of the wafer in the initial state. When the excitation light irradiates the detection point, due to the high energy and thermal effect of the excitation light, the temperature of the wafer surface changes, and at the same time, the charge and electric field distributions inside the wafer also change. These two effects are macroscopically manifested as a change in reflectivity. When the excitation light irradiates the detection point, the reflectivity of the wafer reaches a peak in a very short time, which is the excited state. After that, the sample to be measured 8 undergoes annealing, and the signal received by the second signal receiving system 24 gradually decays to a stable state. By analyzing the modulated light signals in the initial state, the excited state, and the steady state, the wafer defects can be analyzed.

[0135] Since the excitation light is modulated light, that is, the intensity of the excitation light changes periodically with time. As the intensity of the excitation light changes periodically, the physical properties and electrical properties of the wafer surface at the detection point also change periodically. Macroscopically, it is manifested that the reflectivity of this point changes periodically, and its period is the same as the change period of the modulated light. Therefore, on the premise that the intensity of the detection light does not change, the signal received by the second signal receiving system 24 also changes periodically, and is demodulated by the lock-in amplifier 17 at the same modulation frequency to obtain an effective second detection light signal.

[0136] The lock-in amplifier 17 of the present application is purchased from Zurich Instruments, Switzerland. Preprocessing the excitation light emitted by the excitation light source 2 into modulated light with a time-varying intensity feature, and demodulating the signal received by the second signal receiving system 24 are both inherent functions of the lock-in amplifier 17.

[0137] Frequency modulation of the excitation light source 2: A modulation signal of sine plus direct current is output from the output terminal of the lock-in amplifier 17 to the excitation light source laser, and the frequency is provided by the oscillator inside the lock-in amplifier 17.

[0138] Demodulation of the detection signal: After the modulated laser emitted by the excitation light source 2 acts on the sample, the optical properties on the surface of the sample to be measured 8 also change periodically at the modulation frequency. The detection light source hitting the same position on the sample to be measured 8 carries this part of information. The modulated optical signal is received by the signal receiving end, and the optical signal is converted into an electrical signal. By using the digital mixing and filtering processing inside the lock-in amplifier 17, the real modulated optical signal with the same frequency caused by the excitation light modulation is demodulated.

[0139] Periodic change in the light intensity of the modulated light.

[0140] To ensure that the detection light source 1 does not change the charge distribution inside the sample to be measured, so as to measure the real situation of the wafer, the photon energy of the detection light source 1 is lower than the bandgap of any material in the sample to be measured.

[0141] The wafer defect detection device in the present application includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system 24, and is used to process the signals received by the first signal receiving system and the second signal receiving system 24. The signals received by the first signal receiving system and the second signal receiving system 24 are usually electrical signals. After being processed by the central processing unit, the change trend of the light intensity over time can be obtained. The processing of the signals received by the central processing unit for the first signal receiving system and the second signal receiving system 24 is a conventional technical means in the art, and the present application does not make specific limitations on it.

[0142] The central processing unit can be integrated with the body of the detection device or can be in the cloud; it can be a single computer or multiple computers; it can be a physical computer or a virtual machine.

[0143] The wafer defect detection device in the present application may further include a wafer stage 7, an input system, and a display system. And a central processing unit.

[0144] The wafer is placed on the wafer stage 7 and is translated and / or rotated on the horizontal plane along with the wafer stage 7.

[0145] An input system for receiving input information from a user in human-computer interaction; the input system can be directly connected to the body of the detection device or transmit data wirelessly or wired, and can ensure that the input information is input into the device.

[0146] A display system for displaying the output information of the wafer defect detection device in human-computer interaction; the display system can be directly connected to the body of the detection device or transmit data wirelessly or wired, and can ensure that the output information is obtained from the device.

[0147] Both the input system and the display system are connected to the central processing unit. The central processing unit receives the input information, controls the wafer stage 7 to move to the target position according to the input information, controls the wafer defect detection device to perform corresponding detections with the detection conditions given in the input information, processes the received signals, and outputs the test results.

[0148] The above wafer defect detection device may further include an auto-focusing system. The auto-focusing system is located on one side of the dichroic mirror 15, and is used to adjust the focal plane of the excitation light source 2 to coincide with the upper surface of the wafer. The auto-focusing system used in this application is the auto-focusing sensor 18. The above wafer defect detection device may further include an image sensor. In this embodiment, the image sensor is selected as the observation camera 19, which is used to acquire and identify images near the detection point, and illuminate the area around the detection point with the point light source 20 to observe whether there are any abnormal situations during the detection process. It should be noted that in order to avoid affecting the detection results, the wavelength ranges of the light emitted by the auto-focusing system and the point light source 20 should be avoided from being close to the wavelengths of the detection light and the excitation light. Under this precondition, by selecting the dichroic mirrors 14 and 15 with specific wavelength ranges, the detection light and the excitation light can be transmitted through the dichroic mirrors 14 and 15, so that the light emitted by the auto-focusing system and the point light source 20 can be separated from the detection optical path and the excitation optical path.

[0149] The detection method corresponding to this device is as follows:

[0150] S1. Set test parameters through human-computer interaction. The central processing unit executes the test instruction, and the wafer stage 7 carrying the sample to be tested 8 moves the sample to be tested 8 to the test position, and the auto-focusing system adjusts the sample to be tested 8 to be located in the focal plane of the test device;

[0151] S2. Turn on the detection light source 1, the first signal receiving system and the second signal receiving system 24. The first signal receiving system and the second signal receiving system 24 receive a constant signal. At this time, it is the initial state, corresponding to Figure 2 a and Figure 2 the I stage of the test curve in b;

[0152] S3. Keep the detection light source 1 on, turn on the excitation light source 2. The charge distribution of the sample to be measured 8 changes, the temperature at the detection point of the sample to be measured 8 gradually increases, and the signals received by the first signal receiving system and the second signal receiving system 24 both change accordingly, which is called the excited state, corresponding to Figure 2 a and Figure 2 the II stage of the test curve in b; after reaching the excited state, the sample to be measured 8 undergoes annealing (because the excitation light source 2 irradiates the sample to provide heat, and then the sample gradually cools, this process is equivalent to the annealing process), and the signal received by the second signal receiving system 24 gradually decays to a stable state, corresponding to Figure 2 the III stage of the modulated light in b; when the charge distribution of the sample to be measured 8 reaches a new dynamic equilibrium and the temperature at the detection point tends to be stable, the signal received by the first signal receiving system also tends to be stable, corresponding to Figure 2 the III stage of the second harmonic in a; Process the signals received by the first signal receiving system and the second signal receiving system 24 to obtain the wafer defect detection result.

[0153] In the excited state, the change of the signal received by the first signal receiving system is closely related to the electrical properties of the sample. The existence of wafer electrical defects will significantly affect the signal change in the excitation stage. Therefore, by analyzing the signal change in the excitation stage received by the first signal receiving system, such as whether the light intensity change is normal or abnormal, the defect situation can be judged.

[0154] Based on the above detection method, the following steps can also be included:

[0155] S4. After the signal received by the first signal receiving system tends to be stable, continue to keep the detection light source 1 on, and at the same time turn off the excitation light source 2. The captured electrons return to the substrate layer and recombine, and the signal received by the first signal receiving system gradually recovers, which is called the recovery state. When the recovery time is long enough, the signal received by the first signal receiving system recovers to the initial state, corresponding to Figure 2 the IV stage of the second harmonic in a; Process the signal received by the first signal receiving system to obtain the wafer defect detection result.

[0156] S5. Turn off the detection light source 1 and the excitation light source 2, and the test ends.

[0157] Since the recovery state and the excited state are opposite processes. Due to the absence of the excitation light effect, the signal change in the recovery stage is only related to the material itself, and the defect level has been characterized in the excitation stage. Therefore, in the detection of wafer defects, the S4 step can be omitted.

[0158] However, in some special usage scenarios, the signal in the recovery stage finally cannot return to the initial state, and this signal change is also used to characterize the electrical properties of specific samples.

[0159] When detecting wafers processed by a single process, if both the modulated optical signal (the signal received by the second signal receiving system) and the second harmonic signal (the signal received by the first signal receiving system) are abnormal, it is determined that there are wafer defects; if both the modulated optical signal and the second harmonic signal are normal, it is determined that there are no wafer defects; if only one of the modulated optical signal and the second harmonic signal is abnormal, it may be a problem with the equipment itself. Therefore, by corroborating the second harmonic signal and the modulated optical signal with each other, wafer defects can be detected quickly and accurately, avoiding misjudgment due to equipment failures.

[0160] For wafers processed through multiple processes, after detection, if the second harmonic signal is abnormal and the modulated optical signal is also detected as abnormal, it indicates that the ion implantation conditions are abnormal, and there may be other influencing factors that cause the second harmonic signal to be abnormal, such as changes in the oxide layer thickness, charge density, or interface state density, etc.

[0161] If the second harmonic signal is abnormal, but the modulated optical signal is not detected as abnormal, it indicates that the ion implantation conditions are normal, but there are other influencing factors that cause the second harmonic signal to be abnormal, such as changes in the oxide layer thickness, charge density, or interface state density, etc.

[0162] If the second harmonic signal is normal, but the modulated optical signal is abnormal, it indicates that the ion implantation conditions are abnormal, and there are other influencing factors that cause the originally abnormal second harmonic signal to be affected in the reverse direction, such as changes in the oxide layer thickness, charge density, or interface state density, etc.

[0163] If the second harmonic signal is normal and the modulated optical signal is also normal, it indicates that there are no wafer defects.

[0164] By corroborating the second harmonic signal with the modulated optical signal, it can be determined whether there are wafer defects, and the process conditions of wafer manufacturing (such as ion implantation conditions) can be further verified, as well as the changes that occur to the wafer itself before and after the manufacturing process (such as changes in the interface state density, etc.), so as to more accurately determine the specific situation of wafer defects and the specific process that causes the defects.

[0165] Therefore, the wafer defect detection equipment of the present application can not only be used for detecting the defect conditions of the interface or surface of wafers after single-process processing, but also for the defect conditions of wafers processed through multiple processes, and can preliminarily analyze whether the ion implantation conditions are normal or abnormal, facilitating the quick acquisition of the specific process that causes wafer defects. In addition, using the wafer defect detection equipment of the present application can corroborate the detection results of the second harmonic signal and the modulated optical signal, improving the accuracy of the detection results.

[0166] In the actual manufacturing process, an oxide layer, i.e., a silicon dioxide layer, will be generated on the surface of the silicon wafer due to natural oxidation. The principle of modulating optical signal detection is to reflect the ion implantation conditions by measuring the change in reflectivity caused by lattice damage in the silicon substrate. Ultimately, the optical information carried by the reflected light is actually the sum of multiple interface light reflection effects (air to surface oxide layer, surface oxide layer to substrate, and the substrate amorphous layer generated by high-concentration ion implantation damage), that is, it is formed by the coherent superposition of the amplitudes of the reflected light with a refractive index gradient. Therefore, it is necessary to consider the measurement correction of the change in the reflectivity of the actual silicon substrate due to the presence of the oxide layer.

[0167] In actual production, the relationship between the second harmonic signal and the oxide layer thickness t is as Figure 5 shown. By obtaining the value of the second harmonic signal under specific conditions, the oxide layer thickness t at this time can be determined, and based on the oxide layer thickness t, the reflectivity without the oxide layer can be obtained, thus completing the correction step.

[0168] The above-mentioned second harmonic signal selects the second harmonic signal in the excited state. Because it is in the excited state, the second harmonic signal changes with time and involves the initial value (I0), the final value (If), or the average value (Iavg). In order to obtain accurate correction results, it is required that Figure 5 the value of the second harmonic signal used in the curve shown is consistent with the value of the second harmonic signal used when subsequently determining the oxide layer thickness t.

[0169] The specific correction steps are as follows:

[0170] 1. Measure the second harmonic signal in the excited state corresponding to different oxide layer thicknesses t, obtain the relationship between the second harmonic signal and the oxide layer thickness t as shown in Figure 5 , and determine the thickness t of the oxide layer according to the specific second harmonic signal.

[0171] The second harmonic signal at this time can be the initial value (I0), the final value (If), or the average value (Iavg). If the initial value (I0) is used as a reference, the relationship between the initial value (I0) of the second harmonic signal and the oxide layer thickness t is obtained. If the final value (If) is used as a reference, the relationship between the final value (If) of the second harmonic signal and the oxide layer thickness t is obtained. If the average value (Iavg) is used as a reference, the relationship between the average value (Iavg) of the second harmonic signal and the oxide layer thickness t is obtained.

[0172] If the initial value (I0) is used as a reference, according to the relationship between the initial value (I0) of the second harmonic signal and the oxide layer thickness t and the initial value (I0) of the specific second harmonic signal, the corresponding oxide layer thickness t is obtained, and so on. If the final value (If) is used as a reference, then the specific second harmonic signal here selects the final value (If).

[0173] 2. Substitute the thickness t of the oxide layer into the following formula to obtain the refractive index n2 of the substrate;

[0174]

[0175] where r with oxide is the reflectivity of the wafer to the second probe light when there is an oxide layer; r0 is the reflectivity of the oxide layer surface, r1 is the reflectivity of the interface between the oxide layer and the substrate, n1 is the refractive index of the oxide layer, and n2 is the refractive index of the substrate;

[0176] 3. Substitute the refractive index n2 of the substrate into the following formula to obtain the reflectivity r of the wafer to the second probe light when there is no oxide layer without oxide ;

[0177]

[0178] r without oxide is directly related to the degree of internal defects of the wafer. By correcting the reflectivity of the silicon substrate, the reflectivity of the wafer to the second probe light without an oxide layer can be obtained, which can further reflect the degree of internal defects of the wafer.

[0179] Example 2

[0180] Different from Example 1, the excitation light source 2 is divided into a first excitation light and a second excitation light by a third beam splitter 21, and the third beam splitter 21 is a beam splitter.

[0181] When the first probe light and the second probe light share the excitation light source 2, the frequency, power, and incident position of the excitation light source 2 are all completely different. When generating the second harmonic signal, in order to obtain a second harmonic signal with a relatively strong signal and be easily received, it is required that the power of the excitation light source 2 is relatively large; on the contrary, the generation of the modulated optical signal requires that the power of the excitation light source 2 is relatively small. In the case of sharing the excitation light source, the setting of its power can only give priority to the second harmonic signal or the modulated optical signal, and it is impossible to take both into account. For example, if the power is set to 50 mw, at this time, both the second harmonic signal and the modulated optical signal can be obtained, but the signals are both relatively weak.

[0182] In addition, sharing the excitation light source makes the incident position of the laser light source exactly the same, and there may be interference between the generated second harmonic signal and the modulated optical signal. In order to avoid the problems caused by signal interference, the excitation light source is divided into two parts and incident from different positions respectively.

[0183] Such as Figure 3, a third beam splitting device 21 is provided on the incident light path of the excitation light source 2. Here, the third beam splitting device 21 is a third beam splitter, which is used to split the excitation light source 2 into a first excitation light and a second excitation light, and the power ratio of the first excitation light to the second excitation light ≥ 10:1. The first excitation light and the first detection light are used in combination, and the second excitation light and the second detection light are used in combination. The incident paths of the second detection light and the second excitation light coincide. The incident light paths of the first detection light and the second detection light are the same as those in Embodiment 1 and will not be described in detail here.

[0184] When the power ratio of the first excitation light to the second excitation light is 10:1, the power of the first excitation light is relatively large and the power of the second excitation light is relatively small, which can simultaneously meet the requirements of the second harmonic signal and the modulation optical signal. Of course, the power ratio of the first excitation light to the second excitation light can be greater than 10:1. The power of the first excitation light further increases and the power of the second excitation light further decreases, which is beneficial to the detection of both the second harmonic signal and the modulation optical signal.

[0185] The excitation positions of the first excitation light and the second excitation light on the sample to be measured 8 do not coincide. The interval between the excitation positions of the first excitation light and the second excitation light on the sample to be measured 8 is [200μm, 1mm]. The minimum interval between the excitation positions of the first excitation light and the second excitation light on the sample to be measured 8 is 200μm, and the maximum is 1mm. Under this interval, the second harmonic signal and the modulation optical signal do not interfere with each other, avoiding affecting the detection result and ensuring the accuracy of the detection result.

[0186] The detection method corresponding to this device is as follows:

[0187] S1. Set the test parameters through human-computer interaction. The central processing unit executes the test instruction, and the wafer stage 7 carrying the sample to be measured 8 moves the sample to be measured 8 to the test position, and the autofocus system adjusts the sample to be measured 8 to be located in the focal plane of the test device;

[0188] S2. Turn on the detection light source 1, the first signal receiving system and the second signal receiving system 24. The first signal receiving system and the second signal receiving system 24 receive a constant signal, and this is the initial state at this time;

[0189] S3. Keep the detection light source 1 on, turn on the excitation light source 2. The charge distribution of the sample to be measured 8 changes, the temperature at the detection point of the sample to be measured 8 gradually increases, and the signals received by the first signal receiving system and the second signal receiving system 24 both change accordingly, which is called the excited state. After reaching the excited state, the sample to be measured 8 undergoes annealing, and the signal received by the second signal receiving system 24 gradually decays to a stable state. When the charge distribution of the sample to be measured 8 reaches a new dynamic equilibrium and the temperature at the detection point of the sample to be measured 8 tends to be stable, the signal received by the first signal receiving system also tends to be stable. Process the signals received by the first signal receiving system and the second signal receiving system 24 to obtain the wafer defect detection result.

[0190] As a preferred embodiment, the above wafer defect detection method further includes:

[0191] S4. After the signal received by the first signal receiving system tends to be stable, continue to keep the detection light source 1 on, and at the same time turn off the excitation light source 2. The captured electrons return to the substrate layer and recombine, and the signal received by the first signal receiving system gradually recovers, which is called the recovery state. When the recovery time is long enough, the signal received by the first signal receiving system recovers to the initial state.

[0192] S5. Turn off the detection light source 1 and the excitation light source 2. The central processing unit processes the signals received by the first signal receiving system and the second signal receiving system 24, and the test ends.

[0193] Embodiment 3

[0194] Dividing the excitation light source 2 into the first excitation light and the second excitation light through a beam splitter can solve the problem caused by the completely consistent power and incident position of the excitation light. However, when different frequency excitation lights are required to be incident in the optical path, two excitation light sources need to be set. Setting the excitation light source as two can solve the problems of frequency, power and incident position brought by sharing the excitation light source at the same time.

[0195] Different from Embodiment 1, as Figure 4, the excitation light sources are set to two, namely the third excitation light 22 and the fourth excitation light 23. Both the third excitation light 22 and the fourth excitation light 23 are incident at 0°. The incident paths of the third excitation light 22 and the first detection light do not overlap, and the incident paths of the fourth excitation light 23 and the second detection light overlap. The incident optical paths of the first detection light and the second detection light are the same as those in Embodiment 1 and will not be elaborated here. The third excitation light 22 and the first detection light are used in combination, and the fourth excitation light 23 and the second detection light are used in combination. When the power requirements for the second harmonic signal generated by the excitation of the first detection light and the modulated optical signal generated by the excitation of the second detection light are different, at this time, two excitation light sources used in combination with the first detection light and the second detection light are set, and the excitation lights adopt different powers respectively. For example, the power adopted by the third excitation light 22 is [50 mw, 1 w], and the power adopted by the fourth excitation light 23 is [5 mw, 50 mw).

[0196] The material of the wafer to be measured can be selected as silicon or silicon carbide. When the material of the wafer to be measured is changed, the frequencies of the excitation lights used for the first detection light and the second detection light are also different. Therefore, by setting two excitation light sources, different frequencies and powers can be selected for the two excitation light sources.

[0197] In this embodiment, a dual excitation light source is adopted, and the second harmonic signal and the modulated optical signal can be measured separately. At this time, the dual excitation light sources are turned on simultaneously and turned off simultaneously.

[0198] Regarding the test process for the second harmonic signal:

[0199] S1. Set the test parameters. The central processing unit executes the test instruction, and the wafer stage 7 carrying the sample 8 to be measured moves the wafer to the test position, and the autofocus system adjusts the sample 8 to be measured to be located at the focal plane of the test equipment;

[0200] S2. Turn on the detection light source 1 and the first signal receiving system. The first signal receiving system receives a constant signal, and this is the initial state at this time;

[0201] S3. Keep the detection light source 1 on, turn on the third excitation light 22, the charge distribution of the sample 8 to be measured changes, the temperature at the detection point of the sample 8 to be measured gradually rises, and the signals received by the first signal receiving system all change accordingly, which is called the excited state; when the charge distribution of the sample 8 to be measured reaches a new dynamic equilibrium and the temperature at the detection point tends to be stable, the signals received by the first signal receiving system tend to be stable accordingly, which is called the stable state;

[0202] S4. Continue to keep the detection light source 1 on, and at the same time turn off the third excitation light 22. The captured electrons return to the substrate layer and recombine, and the signals received by the first signal receiving system gradually recover, which is called the recovery state. When the recovery time is long enough, the signals received by the first signal receiving system recover to the initial state;

[0203] S5. Turn off the detection light source 1 and the third excitation light 22. The central processing unit processes the signals received by the first signal receiving system, and the test is completed.

[0204] Procedure for testing modulated optical signals:

[0205] S1. Set the test parameters. The central processing unit executes the test instructions. The wafer stage 7 carrying the sample under test 8 moves the sample under test 8 to the test position, and the autofocus system adjusts the sample under test 8 to be located in the focal plane of the test equipment.

[0206] S2. Turn on the detection light source 1 and the second signal receiving system 24. The second signal receiving system 24 receives a constant signal, and this is the initial state at this time.

[0207] S3. Keep the detection light source 1 on, turn on the fourth excitation light 23. The charge distribution of the sample under test 8 changes, and the temperature at the sample detection point gradually increases. The signals received by the second signal receiving system 24 all change accordingly, which is called the excited state. After reaching the excited state, the sample under test 8 undergoes annealing, and the signals received by the second signal receiving system 24 gradually decay to a stable state.

[0208] S4. Turn off the detection light source 1 and the fourth excitation light 23. The central processing unit processes the signals received by the second signal receiving system 24, and the test is completed.

[0209] Example 4

[0210] Different from Example 1, the power of the excitation light source 2 is adjustable. By adjusting the laser of the excitation light source 2, the power can be adjusted.

[0211] The power adjustment range of the excitation light source 2 is 5 mw - 1 w.

[0212] During use, the power of the excitation light source 2 can be set to a first excitation value, and the range of the first excitation value is 5 mw - 50 mw.

[0213] Testing procedure:

[0214] S1. Set the test parameters. The central processing unit executes the test instructions. The wafer stage 7 carrying the sample under test 8 moves the sample under test 8 to the test position, and the autofocus system adjusts the sample under test 8 to be located in the focal plane of the test equipment.

[0215] S2. Turn on the detection light source 1, the first signal receiving system, and the second signal receiving system 24. The first signal receiving system and the second signal receiving system 24 receive constant signals, and this is the initial state at this time.

[0216] S3, keep the detection light source 1 turned on, turn on the excitation light source 2, set the power of the excitation light source 2 to the first excitation value, at this time the power of the excitation light source 2 is less than the excitation light source power required to generate the second harmonic signal, because the power of the excitation light source 2 is small, the charge distribution of the sample does not change significantly, and the first signal receiving system has a weak signal; at the same time, as the temperature at the sample detection point gradually increases, the signal received by the second signal receiving system 24 changes accordingly and is in an excited state; after reaching the excited state, the sample 8 to be tested is annealed, and the signal received by the second signal receiving system 24 gradually decays to a stable state;

[0217] S4, keep the detection light source 1 and the excitation light source 2 turned on, and adjust the power of the excitation light source 2 to the second excitation value, the range of the second excitation value is 50mw-1w, at this time the power of the excitation light source 2 is greater than or equal to the excitation light source power required to generate the second harmonic signal, the charge distribution of the sample 8 to be tested changes, and the signal received by the first signal receiving system changes accordingly, which is called an excited state; when the charge distribution of the sample 8 to be tested reaches a new dynamic equilibrium, the signal received by the first signal receiving system tends to be stable accordingly;

[0218] S5, turn off the detection light source 1 and the excitation light source 2, and the central processing unit processes the signals received by the first signal receiving system and the second signal receiving system 24, and the test ends.

[0219] At the beginning of the detection, the excitation light source 2 outputs excitation light at a relatively low power to meet the excitation conditions required by the second detection light during detection, and to minimize the changes in physical properties of the wafer surface caused by the excitation; when the detection of the second detection light is completed, the excitation light source 2 is adjusted to output excitation light at a relatively high power to meet the excitation conditions required by the first detection light during detection. Even if the physical properties of the wafer surface change significantly due to the excitation process at this time, it will not affect the detection results of the modulated light signal performed previously.

[0220] Although the second harmonic signal detection results performed later can characterize the electrical properties of the test sample 8 at the detection point, they cannot be consistent with the second harmonic signal detection results performed directly. The reason is that when performing modulated light signal detection, the smaller power has already affected the second harmonic signal; and the laser excitation has an annealing effect on the wafer, which will further affect the second harmonic signal. The tester can pre-test the second harmonic of the wafer with standard performance parameters or after standard processes, that is, test the second harmonic signal near the test point (close distance, so that the detection area is in the same state) to obtain a second harmonic signal that has not been annealed and can be used for comparison, and use this value as the standard value or reference value.

[0221] The result of the second harmonic signal detection after the modulated optical signal detection can be compared with the standard value or reference value, and the difference reflects the electrical property difference of the wafer before and after annealing, that is, it quantifies the influence of annealing on the number of internal charges and defects. This feature can be directly used for the yield detection of the material annealing process in the engineering field, with the advantages of fast, efficient and non-destructive detection.

[0222] Example 5

[0223] A computer device, comprising: a processor and a memory;

[0224] The memory is used to store a computer program and transmit the computer program to the processor;

[0225] The processor is used to execute the above-mentioned wafer defect detection method according to the instructions in the computer program.

[0226] Example 6

[0227] A computer-readable storage medium is used to store a computer program, and the computer program is used to execute the above-mentioned wafer defect detection method.

[0228] Example 7

[0229] A product including a computer program, when it runs on a computer device, the computer device executes the above-mentioned wafer defect detection method.

[0230] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A wafer defect detection device, characterized in that, Comprising: A light source, the light source including a detection light source and an excitation light source, the detection light source emitting detection incident light, and the excitation light source emitting excitation incident light; A first beam splitting device, a first beam splitting device is provided in the incident light path of the detection incident light, and the first beam splitting device is used to split the detection incident light emitted by the detection light source into a first detection light and a second detection light; the second detection light coincides with the incident light path of the excitation light source and is incident on the wafer at 0°; A first signal receiving system, a first signal receiving system is provided in the outgoing light path of the first detection light, and is used to receive the detection second harmonic signal emitted by the wafer under the action of the first detection light; A second signal receiving system, a second signal receiving system is provided in the outgoing light path of the second detection light, and is used to receive the reflection signal emitted by the wafer under the action of the second detection light to detect the surface reflectivity of the wafer.

2. The wafer defect detection device according to claim 1, wherein, It further includes a lock-in amplifier, one end of the lock-in amplifier is connected to the excitation light source, and is used to preprocess the excitation light emitted by the excitation light source into modulated light; the other end of the lock-in amplifier is connected to the second signal receiving system, and is used to demodulate the signal received by the second signal receiving system, and the modulated light is modulated light with a time-varying intensity characteristic.

3. The wafer defect detection device according to claim 1, characterized in that, The first signal receiving system includes a polarization beam splitting device, the polarization beam splitting device is provided on the outgoing light path of the first detection light, and is used to separate the generated detection second harmonic signal into a P-polarized signal and an S-polarized signal, and the first signal receiving system further includes a P-signal receiving end and an S-signal receiving end, which respectively receive the P-polarized signal and the S-polarized signal.

4. The wafer defect detection device according to claim 3, wherein A first polarization element is provided on the incident light path of the first detection light, and is used to adjust the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the S-signal receiving end is used to reduce the noise of the second harmonic signal received by the P-signal receiving end, or, When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P-signal receiving end is used to reduce the noise of the second harmonic signal received by the S-signal receiving end.

5. The wafer defect detection device according to claim 1, characterized in that, The photon energy of the detection light source is lower than the band gap width of any material in the wafer to be measured.

6. The wafer defect detection device according to claim 1, characterized in that, The power of the excitation light source is adjustable, and the power adjustment range of the excitation light source is 5mw - 1w.

7. The wafer defect detection device according to claim 1, wherein, The wafer defect detection device further includes a central processing unit, and the central processing unit is connected to the first signal receiving system and the second signal receiving system, and is used to process the signals received by the first signal receiving system and the second signal receiving system.

8. The wafer defect detection device according to any one of claims 1-7, characterized in that, The wafer defect detection device further includes a wafer stage, an input system and a display system; The wafer is placed on the wafer stage and is translated and / or rotated on a horizontal plane along with the wafer stage; The input system is used to receive the input information of the user in human-computer interaction; The display system is used to display the output information of the wafer defect detection device in human-computer interaction.

9. The wafer defect detection device according to claim 8, characterized in that, The wafer defect detection device further includes an autofocus system, which is used to adjust the focal plane of the excitation light source.

10. A wafer defect detection device, characterized in that, Comprising: A light source, the light source including a detection light source and an excitation light source, the detection light source emitting detection incident light, and the excitation light source emitting excitation incident light; A first beam splitting device, a first beam splitting device is arranged in the incident optical path of the detection incident light, for splitting the detection incident light emitted by the detection light source into a first detection light and a second detection light; the first detection light does not coincide with the incident optical path of the excitation light source; A third beam splitting device, a third beam splitting device is arranged in the incident optical path of the excitation light source, for splitting the excitation light source into a first excitation light and a second excitation light, the excitation positions of the first excitation light and the second excitation light on the sample to be measured do not coincide; the second detection light coincides with the incident optical path of the second excitation light and is incident on the wafer at 0°; A first signal receiving system, a first signal receiving system is arranged in the outgoing optical path of the first detection light, for receiving the detection second harmonic signal emitted by the wafer under the action of the first detection light; A second signal receiving system, a second signal receiving system is arranged in the outgoing optical path of the second detection light, for receiving the reflection signal emitted by the wafer under the action of the second detection light to detect the surface reflectivity of the wafer.

11. The wafer defect detection device according to claim 10, characterized in that, It further includes a lock-in amplifier, one end of the lock-in amplifier is connected to the excitation light source, for preprocessing the excitation light emitted by the excitation light source into modulated light; the other end of the lock-in amplifier is connected to the second signal receiving system, for demodulating the signal received by the second signal receiving system, and the modulated light is modulated light with a time-varying intensity characteristic.

12. The wafer defect detection device according to claim 10, wherein, The first signal receiving system includes a polarization beam splitting device, the polarization beam splitting device is arranged on the outgoing optical path of the first detection light, for separating the generated detection second harmonic signal into a P polarization signal and an S polarization signal, and the first signal receiving system further includes a P signal receiving end and an S signal receiving end, respectively receiving the P polarization signal and the S polarization signal.

13. The wafer defect detection device according to claim 12, characterized in that, A first polarization element is arranged on the incident optical path of the first detection light, for adjusting the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the signal receiving system end is used to reduce the noise of the second harmonic signal received by the signal receiving system end, or, When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P signal receiving end is used to reduce the noise of the second harmonic signal received by the S signal receiving end.

14. The wafer defect detection device according to claim 10, wherein The photon energy of the detection light source is lower than the band gap width of any material in the wafer to be measured.

15. The wafer defect detection device according to claim 10, wherein The power ratio of the first excitation light to the second excitation light ≥ 10:

1.

16. The wafer defect detection device according to claim 10, characterized in that, The excitation position interval of the first excitation light and the second excitation light on the wafer to be measured is [200μm, 1mm].

17. The wafer defect detection device according to claim 10, characterized in that, The wafer defect detection device further includes a central processing unit, the central processing unit is connected to the first signal receiving system and the second signal receiving system, for processing the signals received by the first signal receiving system and the second signal receiving system.

18. The wafer defect detection device according to any one of claims 10-17, characterized in that, The wafer defect detection device further includes a wafer stage, an input system and a display system; The wafer is placed on the wafer stage and is translated and / or rotated on the horizontal plane along with the wafer stage; The input system is used to receive the input information of the user during human-computer interaction; The display system is used to display the output information of the wafer defect detection device during human-computer interaction.

19. The wafer defect detection device according to claim 18, characterized in that, The wafer defect detection device further includes an autofocus system for adjusting the focal plane of the excitation light source.

20. A wafer defect detection device, characterized in that, It includes: A light source, which includes a detection light source and an excitation light source. The detection light source emits detection incident light, and the excitation light source emits excitation incident light. The excitation light source includes a third excitation light and a fourth excitation light; A first beam splitting device. A first beam splitting device is arranged in the incident light path of the detection incident light to split the detection incident light emitted by the detection light source into a first detection light and a second detection light; the incident light paths of the first detection light and the third excitation light do not overlap, the incident light paths of the second detection light and the fourth excitation light overlap, and the second detection light, the third excitation light, and the fourth excitation light all enter the wafer at 0°. A first signal receiving system. A first signal receiving system is arranged in the exit light path of the first detection light to receive the detection second harmonic signal emitted by the wafer under the action of the first detection light; A second signal receiving system. A second signal receiving system is arranged in the exit light path of the second detection light to receive the reflection signal emitted by the wafer under the action of the second detection light to detect the surface reflectivity of the wafer.

21. The wafer defect detection device according to claim 20, wherein, It further includes a lock-in amplifier. One end of the lock-in amplifier is connected to the excitation light source to preprocess the excitation light emitted by the excitation light source into modulated light; the other end of the lock-in amplifier is connected to the second signal receiving system to demodulate the signal received by the second signal receiving system, and the modulated light is modulated light with a time-varying intensity characteristic.

22. The wafer defect detection device according to claim 20, characterized in that, The first signal receiving system includes a polarization beam splitting device. The polarization beam splitting device is arranged on the exit light path of the first detection light to separate the generated detection second harmonic signal into a P-polarized signal and an S-polarized signal. The first signal receiving system further includes a P-signal receiving end and an S-signal receiving end to receive the P-polarized signal and the S-polarized signal respectively.

23. The wafer defect detection device according to claim 22, wherein, A first polarization element is arranged on the incident light path of the first detection light to adjust the polarization direction of the first detection light to P polarization or S polarization. When the first polarization element adjusts the polarization direction of the first detection light to P polarization, the S-signal receiving system is used to reduce the noise of the second harmonic signal received by the P-signal receiving end, or When the first polarization element adjusts the polarization direction of the first detection light to S polarization, the P-signal receiving end is used to reduce the noise of the second harmonic signal received by the S-signal receiving end.

24. The wafer defect detection device according to claim 20, wherein, The photon energy of the detection light source is lower than the bandgap width of any material in the wafer to be measured.

25. The wafer defect detection device according to claim 20, wherein, The wafer defect detection device further includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system to process the signals received by the first signal receiving system and the second signal receiving system.

26. The wafer defect detection device according to any one of claims 20-25, characterized in that, The wafer defect detection device further includes a wafer stage, an input system, and a display system; The wafer is placed on the wafer stage and moves horizontally and / or rotates along with the wafer stage; The input system is used to receive the input information of the user during human-computer interaction; The display system is used to display the output information of the wafer defect detection device during human-computer interaction.

27. The wafer defect detection device according to claim 26, wherein, It further includes an autofocus system for adjusting the focal plane of the excitation light source.

28. A wafer defect detection method, which applies the wafer defect detection device described in any one of claims 1-5 or 7-27, is characterized in that, It includes the following steps: S1. Turn on the detection light source. The first signal receiving system and the second signal receiving system respectively receive the signals excited by the first detection light and the second detection light. At this time, the signals are both constant and in the initial state; S2. Keep the detection light source on and turn on the excitation light source at the same time. The charge distribution of the sample to be measured changes, and the temperature at the detection point gradually increases. The signals received by the first signal receiving system and the second signal receiving system change accordingly, and it is in the excited state; After reaching the excited state, the sample to be measured undergoes annealing, and the signal received by the second signal receiving system gradually decays to a stable state; when the charge distribution of the sample to be measured reaches a new dynamic equilibrium and the temperature at the detection point tends to be stable, the signal received by the first signal receiving system also tends to be stable; process the signals received by the first signal receiving system and the second signal receiving system to obtain the wafer defect detection result.

29. A wafer defect detection method according to claim 28, characterized in that, It further includes: S31. After the signal received by the first signal receiving system tends to be stable, continue to keep the detection light source on and turn off the excitation light source at the same time. The captured electrons return to the substrate layer and recombine, and the signal received by the first signal receiving system gradually recovers, which is called the recovery state. When the recovery time is long enough, the signal received by the first signal receiving system recovers to the initial state; process the signal received by the first signal receiving system to obtain the wafer defect detection result.

30. A wafer defect detection method according to claim 28, characterized in that, It further includes: S32. A step of correcting the reflectivity of the wafer to the second detection light according to the signal value received by the first signal receiving system.

31. A wafer defect detection method according to claim 30, wherein, The correction step is: S321. According to the relationship between the second harmonic signal and the thickness t of the oxide layer, obtain the thickness t of the oxide layer when a specific second harmonic signal is obtained; S322. Substitute the oxide layer thickness t into the following formula to obtain the substrate refractive index n2; where r with oxide is the reflectivity of the wafer to the second probe light when there is an oxide layer; r0 is the reflectivity of the oxide layer surface, r1 is the reflectivity of the oxide layer and substrate interface, n1 is the refractive index of the oxide layer, and n2 is the refractive index of the substrate; S323. Substitute the refractive index n2 of the substrate into the following formula to obtain the reflectivity r of the wafer for the second detection light when there is no oxide layer without oxide ; 。 32. A wafer defect detection method, applying the wafer defect detection device described in claim 6, characterized in that, It includes the following steps: S1. Turn on the detection light source. The signals received by the first signal receiving system and the second signal receiving system are both constant and in the initial state; S2. Keep the detection light source on and turn on the excitation light source at the same time. Adjust the power of the excitation light source to the first excitation value, and the first excitation value is less than the power of the excitation light source required to generate the second harmonic signal. At this time, the temperature at the detection point gradually increases, and the signal received by the second signal receiving system changes accordingly and is in the excited state; after reaching the excited state, the sample to be measured undergoes annealing, and the signal received by the second signal receiving system gradually decays to a stable state; S3. Continue to keep the detection light source on and adjust the power of the excitation light source to the second excitation value. The second excitation value is greater than or equal to the power of the excitation light source required to generate the second harmonic signal. At this time, the charge distribution of the sample to be measured changes, and the signal received by the first signal receiving system changes accordingly, which is called the excited state; when the charge distribution of the sample to be measured reaches a new dynamic equilibrium, the signal received by the first signal receiving system tends to be stable; S4. Process the signals received by the first signal receiving system and the second signal receiving system to obtain the wafer defect detection result.

33. The wafer defect detection method according to claim 32, wherein The first excitation value ≥ 5 mw and < 50 mw, and the second excitation value ≥ 50 mw and ≤ 1 w.

34. The wafer defect detection method according to claim 32, wherein, It further includes: S5. A step of correcting the reflectivity of the wafer to the second detection light according to the signal value received by the first signal receiving system.

35. The wafer defect detection method according to claim 34, wherein, The correction step is: S51. Obtain the thickness t of the oxide layer when a specific second harmonic signal is obtained according to the relationship between the second harmonic signal and the thickness t of the oxide layer; S52. Substitute the thickness t of the oxide layer into the following formula to obtain the refractive index n2 of the substrate; where r with oxide is the reflectivity of the wafer to the second detection light when there is an oxide layer; r0 is the reflectivity of the oxide layer surface, r1 is the reflectivity of the interface between the oxide layer and the substrate, n1 is the refractive index of the oxide layer, and n2 is the refractive index of the substrate; S53. Substitute the refractive index n2 of the substrate into the following formula to obtain the reflectivity r of the wafer for the second probe light when there is no oxide layer without oxide ; 。 36. A computer device, characterized in that, It includes: A processor and a memory; The memory is used to store a computer program and transmit the computer program to the processor; The processor is used to execute the wafer defect detection method according to any one of claims 28-31 or claims 32-35 according to the instructions in the computer program.

37. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program, and the computer program is used to execute the wafer defect detection method according to any one of claims 28-31 or claims 32-35.

38. A product comprising a computer program, characterized in that, When it runs on a computer device, the computer device executes the wafer defect detection method according to any one of claims 28-31 or claims 32-35.

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