CN118883564B

CN118883564B - Wafer defect detection equipment and detection method

Info

Publication number: CN118883564B
Application number: CN202411031439.0A
Authority: CN
Inventors: 王菲; 赵威威; 黄崇基
Original assignee: Shanghai Weichong Semiconductor Equipment Co ltd
Current assignee: Shanghai Weichong Semiconductor Equipment Co ltd
Priority date: 2024-07-30
Filing date: 2024-07-30
Publication date: 2025-07-15
Anticipated expiration: 2044-07-30
Also published as: CN118883564A

Abstract

The invention provides wafer defect detection equipment and a detection method, wherein the detection equipment comprises a light source, a first light splitting device, a first signal receiving system and a second signal receiving system, wherein the light source comprises 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, the first light splitting device is arranged in an incident light path of the detection incident light and is used for splitting the detection incident light emitted by the detection light source into first detection light and second detection light, the second detection light coincides with the incident light path of the excitation light source and is incident to a wafer at an angle of 0 DEG, the first signal receiving system is arranged in an emergent light path of the first detection light and is used for receiving a detection second harmonic signal emitted by the wafer under the action of the first detection light, and the second signal receiving system is arranged in an emergent light path of the second detection light and is used for receiving a signal emitted by the wafer under the action of the second detection light. The detection equipment disclosed by the invention improves the detection efficiency and the reliability of the detection result.

Description

Wafer defect detection equipment and detection method

Technical Field

The invention relates to the field of semiconductors, in particular to wafer defect detection equipment and a wafer defect detection method.

Background

The wafer processing process includes multiple processes, such as photolithography, etching, deposition, etching, etc., each of which may introduce defects, such as residue of a photolithographic layer, non-uniformity of etching depth, etc. These processing defects directly affect the performance and reliability of the semiconductor device, and thus it is important to detect defects on the wafer.

Currently, methods for detecting defects on wafers mainly include destructive and non-destructive methods. Destructive detection methods play a very important role in analysis of surface damage of optical materials and semiconductor crystal materials, but these methods have the disadvantages of time consumption, strong experience dependence and the like in addition to irreversible damage to samples.

The second harmonic signal detection is a novel nondestructive detection method. The second harmonic signal detection is a technology for characterizing and diagnosing defects of a wafer by exciting, collecting and analyzing second harmonic signals generated at the interface and the surface of the wafer. The principle is that defects exist in the inner parts and interfaces of various film layers in a wafer, after laser reaches a substrate, electronic transition in the substrate is excited, the electronic transition is captured by some defects, and a second harmonic signal is dynamically generated. This approach allows detection of a number of defects associated with electrical properties, such as interface states, accumulated charges, defects associated with film quality, such as fixed charges, defective charges, mobile charges, lattice defects, etc., and surface charge distribution associated with surface quality, etc.

The second harmonic signal detection is used for detecting the defects of the wafer, has not been widely popularized, and is found in practical application that when the detection result is abnormal, it is difficult to quickly judge what defects exist in the wafer. In addition, because the detecting equipment may have abnormality to cause deviation, a single detecting method cannot be completely reliable, and the requirement of rapid and accurate detection under a new process cannot be met.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention provides a wafer defect detection apparatus, which divides the detection incident light emitted by the detection light source into a first detection light and a second detection light, the first signal receiving system receives the detection second harmonic signal emitted by the first detection light, the second signal receiving system receives the signal emitted by the second detection light, and the signals obtained by the first signal receiving system and the second signal receiving system are compared and verified with each other to obtain a wafer defect detection result, so that the problem that a single detection method cannot verify each other is solved, the detection efficiency and the detection accuracy are improved, and the reliability of the detection result is ensured. Therefore, the invention also provides a wafer defect detection method

In a first aspect of the present invention, there is provided a wafer defect inspection apparatus comprising:

The light source comprises a detection light source and an excitation light source, wherein the detection light source emits detection incident light, and the excitation light source emits excitation incident light;

The device comprises a first light splitting device, a second light splitting device, a first light splitting device and a second light splitting device, wherein the first light splitting device is arranged in an incident light path of the detection incident light and is used for splitting the detection incident light emitted by the detection light source into first detection light and second detection light, and the second detection light coincides with the incident light path of the excitation light source and is incident to a wafer at an angle of 0 DEG;

the first signal receiving system is arranged in an emergent light path of the first detection light and is used for receiving a detection second harmonic signal emitted by the wafer under the action of the first detection light;

And the second signal receiving system is arranged in an emergent light path of the second detection light and is used for receiving a signal sent by the wafer under the action of the second detection light.

The wafer defect detection device further comprises a phase-locked amplifier, wherein one end of the phase-locked amplifier is connected with the excitation light source and used for preprocessing excitation light emitted by the excitation light source into modulated light, the other end of the phase-locked amplifier is connected with the second signal receiving system and used for demodulating signals received by the second signal receiving system, and the modulated light is modulated light with time-varying intensity.

As a preferred embodiment, the first signal receiving system includes a polarization beam splitter, where the polarization beam splitter is disposed on an outgoing optical path of the first detection light and is configured to split 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 that respectively receive the P-polarized signal and the S-polarized signal.

As a preferred embodiment, a first polarizing element is disposed on an incident light path of the first probe light, and is configured to adjust a polarization direction of the first probe light to be P-polarized or S-polarized, and when the first polarizing element adjusts the polarization direction of the first probe light to be P-polarized, the S-signal receiving end is used to reduce noise of the second harmonic signal received by the P-signal receiving end, or,

And when the first polarization element adjusts the polarization direction of the first detection light to be S polarization, the P signal receiving end is used for reducing noise of the second harmonic signal received by the S signal receiving end.

As a preferred embodiment, the incident angle of the first probe light is adjusted to be in the range of 15 ° -75 °.

As a more preferable embodiment, the incident angle of the first probe light is 45 °.

As a preferred embodiment, the photon energy of the detection light source is lower than the forbidden bandwidth of any material in the wafer to be detected.

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

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

As a preferred embodiment, the wafer defect detecting 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 configured to process signals received by the first signal receiving system and the second signal receiving system.

As a preferred embodiment, the wafer defect detection apparatus further comprises a wafer carrier, an input system, and a display system;

the wafer is placed on the wafer carrying platform and translates and/or rotates along with the wafer carrying platform on the horizontal plane;

The input system is used for receiving input information of a user in man-machine interaction;

the display system is used for displaying the output information of the wafer defect detection equipment in man-machine interaction.

As a more preferred embodiment, the wafer defect detection apparatus further comprises an autofocus system for adjusting the focal plane of the excitation light source.

In a second aspect of the present invention, there is provided a wafer defect inspection apparatus comprising:

The first light splitting device is arranged in an incident light path of the detection incident light and is used for splitting the detection incident light emitted by the detection light source into first detection light and second detection light, and the first detection light is not overlapped with the incident light path of the excitation light source;

The third light splitting device is arranged in an incident light path of the excitation light source and is used for splitting the excitation light source into first excitation light and second excitation light, and excitation positions of the first excitation light and the second excitation light on a sample to be detected are not overlapped;

And the second signal receiving system is arranged in the emergent light path of the second detection light and is used for receiving signals sent by the wafer under the action of the second detection light.

As a preferred embodiment, the incident angle of the first detection light is adjusted to 15-75 DEG

As a more preferable embodiment, the ratio of the power of the first excitation light to the power of the second excitation light is more than or equal to 10:1.

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

As a more preferred embodiment, the wafer defect detecting apparatus further includes a central processing unit connected to the first signal receiving system and the second signal receiving system, for processing signals received by the first signal receiving system and the second signal receiving system.

In a third aspect of the present invention, there is provided a wafer defect inspection apparatus comprising:

The light source comprises 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 comprises third excitation light and fourth excitation light;

the device comprises a first light splitting device, a second light splitting device, a third light splitting device, a fourth light splitting device, a first light splitting device, a second light splitting device and a third light splitting device, wherein the first light splitting device is arranged in an incident light path of detection incident light and is used for splitting detection incident light emitted by a detection light source into first detection light and second detection light;

In a fourth aspect of the present invention, a wafer defect detecting method is provided, and the wafer defect detecting apparatus includes the following steps:

S1, turning on a detection light source, and respectively receiving signals excited by first detection light and second detection light by a first signal receiving system and a second signal receiving system, wherein the signals are constant and are in an initial state;

S2, keeping the detection light source on, simultaneously turning on the excitation light source, enabling the charge distribution of the sample to be detected to change, enabling the temperature at the detection point to gradually rise, enabling signals received by the first signal receiving system and the second signal receiving system to change to be in an excited state, annealing the sample to be detected after the sample to be detected reaches the excited state, enabling the signals received by the second signal receiving system to gradually decay to a stable state, enabling the signals received by the first signal receiving system to be stable when the charge distribution of the sample to be detected reaches new dynamic balance and the temperature at the detection point is stable, and processing the signals received by the first signal receiving system and the second signal receiving system to obtain wafer defect detection results.

As a preferred embodiment, the wafer defect detection method further includes:

S31, after the signals received by the first signal receiving system tend to be stable, the detection light source is kept on, the excitation light source is turned off, captured electrons return to the substrate layer again to be compounded, the signals received by the first signal receiving system are recovered gradually, namely recovered state, when the recovered time is long enough, the signals received by the first signal receiving system are recovered to the initial state, and the signals received by the first signal receiving system are processed to obtain the wafer defect detection result.

As a preferred embodiment, the wafer defect detection method further includes:

S32, correcting the reflectivity of the second detection light by the wafer according to the signal value received by the first signal receiving system.

As a preferred embodiment, the above-mentioned correction steps are:

S321, obtaining the thickness t of the oxide layer when a specific second harmonic signal is obtained according to the relation between the second harmonic signal and the thickness t of the oxide layer;

S322, substituting the thickness t of the oxide layer into the following formula to obtain the refractive index n ₂ of the substrate;

Wherein r _with _oxide is the reflectivity of the wafer to the second detection light when the oxide layer exists, r ₀ is the reflectivity of the oxide layer surface, r ₁ is the reflectivity of the oxide layer and substrate interface, n ₁ is the refractive index of the oxide layer, and n ₂ is the refractive index of the substrate;

S323, substituting the refractive index n ₂ of the substrate into the following formula to obtain the reflectivity r _without _oxide of the wafer to the second detection light when the oxide layer does not exist;

In a fifth aspect of the present invention, a wafer defect detecting method is provided, and the wafer defect detecting apparatus includes the following steps:

S1, turning on a detection light source, wherein signals received by a first signal receiving system and a second signal receiving system are constant and are in an initial state;

S2, keeping the detection light source on, simultaneously turning on the excitation light source, and adjusting the power of the excitation light source to be a first excitation value, wherein the first excitation value is smaller than the excitation light source power required by generating a second harmonic signal, at the moment, the temperature at the detection point gradually rises, the signal received by the second signal receiving system changes along with the temperature rise, and the signal is in an excited state;

S3, continuously keeping the detection light source on, and simultaneously adjusting the power of the excitation light source to be a second excitation value, wherein the second excitation value is larger than or equal to the excitation light source power required by generating a second harmonic signal, at the moment, the charge distribution of the sample to be detected changes, and the signal received by the first signal receiving system changes along with the change, namely an excited state;

s4, processing signals received by the first signal receiving system and the second signal receiving system to obtain wafer defect detection results.

As a preferred embodiment, the first excitation value is equal to or greater than 5mw and less than 50mw, and the second excitation value is equal to or greater than 50mw and less than 1w.

As a preferred embodiment, the wafer defect detection method further includes:

s5, correcting the reflectivity of the second detection light by the wafer according to the signal value received by the first signal receiving system.

As a preferred embodiment, the above-mentioned correction steps are:

s51, obtaining the thickness t of the oxide layer when a specific second harmonic signal is obtained according to the relation between the second harmonic signal and the thickness t of the oxide layer;

s52, substituting the thickness t of the oxide layer into the following formula to obtain the refractive index n ₂ of the substrate;

s53, substituting the refractive index n ₂ of the substrate into the following formula to obtain the reflectivity r _without _oxide of the wafer to the second detection light when the oxide layer does not exist;

in a sixth aspect of the invention, a computer device is provided, comprising a processor and a memory;

The memory is used for storing a computer program and transmitting the computer program to the processor;

the processor is configured to execute the wafer defect detection method according to instructions in the computer program.

In a seventh aspect of the present invention, there is provided a computer readable storage medium storing a computer program for executing the above-described wafer defect detection method.

In an eighth aspect of the present invention, there is provided a product comprising a computer program which, when run on a computer device, performs the above-described wafer defect detection method.

Compared with the prior art, the invention has the following beneficial effects:

(1) The wafer defect detection equipment provided by the invention has the advantages that two light paths are arranged, one light path is used for incidence on a wafer to generate a second harmonic signal so as to detect defect charges, mobile charges, lattice defects and surface charge distribution uniformity, the other light path is used for incidence on the wafer at an angle of 0 DEG, the lattice defects or the lattice defects are detected through the reflectivity change generated by the interface and the surface of the wafer, the two light paths are mutually interfered to a certain extent due to different detection principles, and the detection results are mutually verified and compared, so that the wafer defect detection result is finally obtained, the detection efficiency is improved, the detection precision is maintained, and the reliability of the detection result is ensured.

(2) The wafer defect detection equipment provided by the invention has the advantages that the light splitting device is arranged, the same detection light source is used for splitting two beams of detection light for detecting the wafer defects under two different detection principles, the use of components is simplified, the equipment is convenient to install and integrate, the detection scene is expanded, and the rapid nondestructive detection function in the chip manufacturing process is realized.

The conception, specific structure, and technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, features, and effects of the present invention.

Drawings

FIG. 1 is a schematic diagram of a wafer defect inspection apparatus according to embodiment 1 of the present invention;

Fig. 2 is a graph of signal variation received by the first signal receiving system and the second signal receiving system of the wafer defect detection apparatus according to embodiment 1 of the present invention, wherein fig. 2a is a graph of signal variation received by the first signal receiving system, and fig. 2b is a graph of signal variation received by the second signal receiving system;

FIG. 3 is a schematic diagram of a wafer defect inspection apparatus according to embodiment 2 of the present invention;

FIG. 4 is a schematic diagram of a wafer defect inspection apparatus according to embodiment 3 of the present invention;

fig. 5 is a graph of the relationship between the second harmonic signal and oxide layer thickness.

The device comprises a detection light source 1, an excitation light source 2, a first light-splitting device 3, a first reflecting mirror 4, a second reflecting mirror 5, a first collimating lens 6, a wafer carrying platform 7, a sample 8 to be detected, a polarization light-splitting device 9, a P signal receiving end 10, an S signal receiving end 11, a polarization light-splitting prism 12, a fourth light-splitting device 13, a first dichroic mirror 14, a second dichroic mirror 15, a second collimating lens 16, a phase-locking amplifier 17, an automatic focusing sensor 18, an observation camera 19, a point light source 20, a third light-splitting device 21, third excitation light 22, fourth excitation light 23 and a second signal receiving system 24.

Detailed Description

The invention is further described with reference to the following detailed description in order to make the technical means, the inventive features, the achieved objects and the effects of the invention easy to understand. The present invention is not limited to the following examples.

It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the invention to the extent that it can be practiced, since modifications, changes in the proportions, or otherwise, used in the practice of the invention, are not intended to be critical to the essential characteristics of the invention, but are intended to fall within the spirit and scope of the invention.

The second harmonic signal detection method is a method for characterizing and diagnosing wafer defects by exciting, collecting and analyzing second harmonic signals generated by the interface and the surface of the wafer, and can detect the conditions of defective charges, mobile charges, lattice defects, surface charge distribution uniformity and the like. However, when the method is used, if the detection result is abnormal, the abnormal result cannot be rapidly judged to be only caused by the wafer defect or caused by the fault of the detection equipment. In addition, the second harmonic signal detection method is mainly used for detecting mobile charges and defective charges under the limitation of a detection principle. Because the second harmonic detection is very sensitive to other parameters of the wafer (such as oxide film thickness, interface state charge, etc.), the time-varying second harmonic detection (time-DEPENDENT SHG, abbreviated as second harmonic detection in the present invention) mode selected in the present invention has no special detection capability for lattice defects than modulated light detection, and the wafer defect condition cannot be comprehensively and accurately reflected only by the time-varying second harmonic detection.

The application aims to solve the technical problems, an optical path is added on the basis of a second harmonic signal detection method, detection light is divided into first detection light and second detection light, the first detection light and excitation light are matched to generate a second harmonic signal, defect charge, mobile charge, lattice defect and surface charge distribution uniformity are detected, the second detection light is incident at 0 ℃, the second detection light and the excitation light jointly act to reflect reflectivity changes generated by a wafer interface and a surface, the lattice defect or lattice damage is detected, and the two are mutually verified, so that the actual condition of the wafer defect is obtained.

Example 1

Referring to fig. 1, a wafer defect inspection apparatus includes:

The light source comprises a detection light source 1 and an excitation light source 2, wherein the detection light source 1 emits detection incident light, and the excitation light source 2 emits excitation incident light;

The first light splitting device 3 is used for splitting the detection incident light emitted by the detection light source 1 into first detection light and second detection light, wherein the first light splitting device 3 can select a spectroscope, and the second detection light coincides with the incident light path of the excitation light source 2 and is incident on the wafer at 0 DEG;

The first signal receiving system is arranged in the emergent light path of the first detection light and is used for receiving a detection second harmonic signal emitted by the wafer under the action of the first detection light;

The first signal receiving system includes a polarization beam splitter 9, a P signal receiving terminal 10, and an S signal receiving terminal 11. A polarization beam splitter 9 for separating the generated detected second harmonic signal into a P-polarized signal and an S-polarized signal, and a P-signal receiving terminal 10 and an S-signal receiving terminal 11 for receiving the generated P-polarized signal and S-polarized signal, respectively. The P signal receiving terminal 10 and the S signal receiving terminal 11 each use a photomultiplier tube (PMT) as a signal receiver.

The second signal receiving system 24 is disposed in the outgoing light path of the second probe light, and the second signal receiving system 24 is configured to receive a signal sent by the wafer under the action of the second probe light.

The light source of the wafer defect detection device comprises a detection light source 1 and an excitation light source 2, wherein the detection light source 1 and the excitation light source 2 are both lasers. "detecting" means that the incident light emitted from the detection light source is coupled with a structure having non-central symmetry to generate a second harmonic signal, and the lattice defect (such as interface state, fixed charge, impurity atom, etc.) is usually a coupling center, so that the generated second harmonic signal can be used to characterize the defect charge, mobile charge, lattice defect, surface charge distribution uniformity, etc. of the sample. By "excitation" is meant that photons injected by the excitation light source 2 in the detection region are absorbed by electrons, so that bound electrons in the valence band of the semiconductor layer of the sample to be measured may acquire enough energy to be excited into the semiconductor conduction band as free electrons that may be trapped by interface state defects or absorb more photons to make them energy enough to cross the barrier into the oxide layer, and eventually, at the interface or surface of the sample, a substantial charge build-up is formed, a process known as electron build-up, which can be "detected" by the second harmonic. In summary, the "excitation" can continuously change the internal charge distribution state of the sample to be measured, while the "detection" can characterize the continuous change of the sample to be measured, and the wafer defect can be measured and analyzed through long-time signal collection of the sample to be measured.

The detection light source 1 in the wafer defect detection equipment emits laser, the emitted laser is divided into first detection light and second detection light under the action of the first light-splitting device 3, an incident light path formed by the first detection light is sequentially transmitted to a sample 8 to be detected (the sample 8 to be detected and the wafer to be detected are the same in meaning and refer to the wafer) on the wafer carrier 7 through the first reflecting mirror 4, the second reflecting mirror 5 and the first collimating lens 6, the incident light is reflected by the sample 8 to generate a second harmonic signal, the second harmonic signal is transmitted to the polarization light-splitting device 9, the polarization light-splitting device 9 is a polarization spectroscope, the polarization light-splitting device 9 separates the second harmonic signal into a P polarization signal and an S polarization signal, the P polarization signal is transmitted to the P signal receiving end 10, and the S polarization signal is transmitted to the S signal receiving end 11.

The second detection light and the incident light path of the excitation light source 2 are coincident, and are incident to the wafer at 0 degrees, namely, are incident perpendicular to the surface of the wafer. The incident light path formed by the second detection light is transmitted to the sample 8 to be detected on the wafer carrier 7 through the polarization beam splitter prism 12, the fourth beam splitter device 13, the first dichroic mirror 14, the second dichroic mirror 15 and the second collimating lens 16 in sequence, the second detection light returns along the original light path direction after reflection occurs, and the generated signal is received by the second signal receiving system 24.

The arrangement of the first collimating lens 6 and the second collimating lens 16 enables the light path to be transmitted more accurately.

The first probe light obtains a second harmonic signal by detecting an electron accumulation process at the interface or surface of the sample 8 to be measured, which is received by the first signal receiving system. By analyzing the signal change received by the first signal receiving system, the defect charge, the mobile charge, the lattice defect, the surface charge distribution uniformity and the like can be judged, but the second harmonic signal detection has relatively weak detection capability on the lattice defect based on the limitation of the detection principle. The incident light paths of the second detection light and the excitation light source 2 are coincident, and are incident on the wafer at 0 degrees, namely, the incident light is perpendicular to the surface of the wafer, the second detection light returns along the original light path direction after reflection, and as the second detection light is reflected by the surface of the wafer once, the intensity of the second detection light is reduced by a part, and the change of the signal intensity of the second detection light received by the second signal receiving system 24 reflects the change of the reflectivity of the wafer, so that the condition of lattice defects or lattice damage is reflected.

The first detection light and the second detection light are mutually independent light paths, the first detection light signal received by the first signal receiving system and the second detection light signal received by the second signal receiving system 24 have small influence on each other, can be independently judged, mutually verify and mutually supplement, and can comprehensively reflect the wafer defect condition.

The following describes two detection means in the present invention:

A. for second harmonic detection, the incidence angle of the first probe light is in the range of 15 DEG to 75 deg. For convenience of installation, the incident angle of the first probe light is set to 45 °. The effect of the angle of incidence on the second harmonic is mainly reflected in the P-polarized component of the second harmonic, since the P-component is the sum of the vectors in both the incident and perpendicular directions. Thus, by adjusting the angle of incidence, certain components in the second order polarization tensor of the sample 8 to be measured can be quantitatively analyzed.

Optionally, a first polarizing element (not shown in the figure) is disposed on the incident light path of the first detection light, where the first polarizing element is a polarizing plate, and is used to adjust the polarization direction of the first detection light to be P-polarization or S-polarization. When the polarization direction of the first detection light is adjusted to be P polarization by the first polarization element, the second harmonic of the S direction is not generated theoretically, however, in actual measurement, the second harmonic signal of the S outgoing light path is not zero due to a small deviation of the angle of the polarizer or affected by other factors. Therefore, the second harmonic signal received by the P signal receiving terminal 10 is noise-reduced using the S signal receiving terminal 11. When the first polarization element adjusts the polarization direction of the first probe light to S polarization, the second harmonic signal received by the S signal receiving end 11 is noise reduced by the P signal receiving end 10.

B. For modulated light detection, in order to improve the detection sensitivity, so that weak signals generated by the combined action of the detection light and the excitation light are more easily received by the signal receiving system, the excitation light is usually preprocessed into modulated light by using a modulation technique. Modulated light refers to light in which certain parameters of the light wave, such as amplitude, frequency, phase, polarization state, duration, etc., change according to a certain rule. The modulation optical technology refers to a modulation technology for superimposing an information-carrying signal on a carrier light wave, and is essentially modulating one or more parameters of a unit vector, an amplitude, a carrier frequency and a phase in a polarization direction. The modulation method is mainly divided into direct modulation, intra-cavity modulation and extra-cavity modulation. The direct modulation method is to directly control the pumping source of the laser (such as controlling the injection current of the semiconductor laser) by an external signal, so that certain parameters of the laser are modulated.

The application adopts a direct modulation method, and adopts a lock-in amplifier 17 to preprocess the excitation light so that the excitation light is changed into modulated light. The wafer defect detection device comprises a phase-locked amplifier 17, wherein one end of the phase-locked amplifier 17 is connected with the excitation light source 2 and is used for preprocessing excitation light emitted by the excitation light source 2 into modulated light, and the other end of the phase-locked amplifier 17 is connected with the second signal receiving system 24 and is used for demodulating signals received by the second signal receiving system 24 and the modulated light is modulated light with time-varying intensity characteristics.

The excitation light source 2 may be provided in one or two. When the number of the first detection light and the second detection light is one, the excitation light is excited, and the first signal receiving system and the second signal receiving system 24 respectively receive signals emitted by the action of the first detection light and the second detection light. When the number of the excitation light sources 2 is two, each detection light acts with one excitation light source 2 respectively, so that signals emitted by the first detection light and the second detection light do not influence each other and do not interfere each other.

In this embodiment, the excitation light source 2 is provided as one, and the first detection light and the second detection light share the excitation light source 2. The excitation light source 2 is preprocessed by a phase-locked amplifier 17 to become modulated light. When the excitation light source 2 is turned off, the charge distribution at the detection point starts to recover, and returns to the initial state after a period of time, at the moment, the second harmonic signal generated by the excitation of the first detection light returns to the initial state, and the wafer defect can be analyzed by analyzing the second harmonic signal in the initial state and the steady state. The excitation light source 2 changes from non-modulated light to modulated light so that the intensity of the generated second harmonic signal periodically changes, but does not affect the analysis of the second harmonic signal.

The second probe light and the excitation light source 2 have the same incident path, and both of them are incident on the sample 8 to be measured at 0 °. Since the excitation light source 2 is modulated light, the signal received by the second signal receiving system 24 is referred to as a modulated light signal for convenience of description. The second signal receiving system 24 includes a second signal receiver, which is a photodiode. The second detection light is incident to the sample 8 to be detected at 0 DEG, and returns along the original light path direction after reflection, and when the excitation light source 2 is not present, the signal received by the second signal receiving system 24 is a constant value. The intensity of the second probe light is reduced by a portion after the second probe light is reflected by the wafer, and the second signal receiving system 24 receives the second probe light intensity, which actually reflects the reflectivity R0 of the wafer in the initial state. When the excitation light irradiates to the detection point, the surface temperature of the wafer changes due to the high energy and the thermal effect of the excitation light, and meanwhile, the electric charge and electric field distribution inside the wafer also change, and the two effects are macroscopic changes of reflectivity. When the excitation light irradiates the detection point, the reflectivity of the wafer reaches a peak value in a short time, which is an excited state. Then, the sample 8 to be tested is annealed, the signal received by the second signal receiving system 24 is gradually attenuated to a stable state, and the wafer defect can be analyzed by analyzing the modulated optical signals in the initial state, the excited state and the stable state.

Since the excitation light is modulated light, i.e. the intensity of the excitation light varies periodically with time. As the intensity of the excitation light periodically changes, the physical properties and electrical properties of the wafer surface at the detection point also periodically change, macroscopically showing that the reflectivity of the point will periodically change, with the period being the same as the period of the change of the modulated light. Accordingly, 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 at the same modulation frequency by the lock-in amplifier 17, so as to obtain an effective second detection light signal.

The lock-in amplifier 17 of the present application is available from zurich instruments, switzerland, and is an inherent function of the lock-in amplifier 17 in preprocessing the excitation light emitted from the excitation light source 2 into modulated light having a time-varying characteristic in intensity and demodulating the signal received by the second signal receiving system 24.

The frequency modulation of the excitation light source 2 is that a sine plus direct current modulation signal is output to the excitation light source laser by the output end of the phase-locked amplifier 17, and the frequency is provided by an oscillator inside the phase-locked amplifier 17.

Demodulation of detection signals, namely after modulated laser emitted by an excitation light source 2 acts on a sample, optical properties of the surface of the sample 8 to be detected also change periodically at a modulation frequency, the detection light source is beaten at the same position of the sample 8 to be detected to carry the information, a modulated light signal is received by a signal receiving end, the light signal is converted into an electric signal, and a real modulated light signal with the same frequency caused by excitation light modulation is demodulated by digital mixing and filtering processing in a lock-in amplifier 17.

The intensity of the modulated light varies periodically.

In order to ensure that the detection light source 1 does not change the charge distribution in the sample to be detected so as to measure the real situation of the wafer, the photon energy of the detection light source 1 is lower than the forbidden bandwidth of any material in the sample to be detected.

The wafer defect detecting device comprises a central processing unit, wherein the central processing unit is connected with the first signal receiving system and the second signal receiving system 24 and is used for processing 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, and the trend of light intensity over time can be obtained after the signals are processed by the central processing unit. The processing of the signals received by the first signal receiving system and the second signal receiving system 24 by the central processing unit is a conventional technical means in the art, and the present application is not limited thereto.

The central processing unit can be integrated with the machine body of the detection equipment or can be located at the cloud end, can be one computer or a plurality of computers, and can be a physical computer or a virtual machine.

The wafer defect detection apparatus of the present application may further include a wafer stage 7, an input system, and a display system. And a central processing unit.

The wafer is placed on the wafer carrier 7 and translated and/or rotated in a horizontal plane with the wafer carrier 7.

The input system can be directly connected with the machine body of the detection equipment, can also perform data transmission in a wireless or wired mode, and can ensure that the input information is input into the device.

The display system can be directly connected with the machine body of the detection equipment, can also perform data transmission in a wireless or wired mode, and can ensure that the output information is obtained from the device.

The input system and the display system are both connected with the central processing unit, the central processing unit receives input information, controls the wafer carrier 7 to move to a target position according to the input information, controls the wafer defect detection equipment to carry out corresponding detection according to given detection conditions in the input information, processes the received signals, and outputs a test result.

The above-described wafer defect detecting apparatus may further include an autofocus system, which is located at one side of the second dichroic mirror 15, for adjusting the focal plane of the excitation light source 2 so as to coincide with the upper surface of the wafer. The autofocus system used in the present application is an autofocus sensor 18. The wafer defect detecting device may further include an image sensor, in which an observation camera 19 is selected for the image sensor in this embodiment, so as to acquire and identify an image near the detecting point, and the point light source 20 is used to illuminate the area around the detecting point, so as to observe whether an abnormal situation occurs in the detecting process. In order to avoid affecting the detection result, the wavelength range of the light emitted from the autofocus system and the point light source 20 should be kept from being close to the wavelengths of the probe light and the excitation light. Under the precondition, by selecting the first dichroic mirror 14 and the second dichroic mirror 15 of a specific wavelength range, the detection light and the excitation light are transmitted through the first dichroic mirror 14 and the second dichroic mirror 15, so that the light emitted from the autofocus system and the point light source 20 can be separated from the detection light path and the excitation light path.

The detection method corresponding to the equipment comprises the following steps:

s1, setting test parameters through man-machine interaction, executing a test instruction by a central processing unit, moving a wafer carrying platform 7 carrying a sample 8 to be tested to a test position, and adjusting the sample 8 to be tested to be positioned on a focal plane of test equipment by an automatic focusing system;

S2, turning on the detection light source 1, the first signal receiving system and the second signal receiving system 24, wherein the first signal receiving system and the second signal receiving system 24 receive constant signals, and the constant signals are in an initial state at this time, and correspond to a stage I of a test curve in FIG. 2a and FIG. 2 b;

s3, keeping the detection light source 1 on, turning on the excitation light source 2, changing the charge distribution of the sample 8 to be detected, gradually increasing the temperature at the detection point of the sample 8 to be detected, changing the signals received by the first signal receiving system and the second signal receiving system 24, namely, the excited state, corresponding to the stage II of the test curve in FIG. 2a and FIG. 2b, annealing the sample 8 to be detected after the excited state is reached (the sample is irradiated by the excitation light source 2 and is provided with heat, and then the sample is gradually cooled, which is equivalent to the annealing process), gradually attenuating the signal received by the second signal receiving system 24 to the stable state, corresponding to the stage III of the modulated light in FIG. 2b, and when the charge distribution of the sample 8 to be detected reaches the new dynamic balance and the temperature at the detection point is stable, the signal received by the first signal receiving system is also stable, corresponding to the stage III of the second harmonic in FIG. 2a, and processing the signal received by the first signal receiving system and the second signal receiving system 24 to obtain the wafer defect detection result.

When in an excited state, the signal change condition received by the first signal receiving system is closely related to the electrical property of the sample, and the signal change in the excited stage is obviously influenced by the existence of the wafer electrical defect, so that the defect condition is judged by analyzing the signal change in the excited stage received by the first signal receiving system, such as normal or abnormal light intensity change.

Based on the detection method, the method can further comprise the following steps:

S4, after the signals received by the first signal receiving system tend to be stable, the detection light source 1 is kept on, the excitation light source 2 is turned off, captured electrons return to the substrate layer again to be compounded, the signals received by the first signal receiving system are gradually recovered, namely recovered state, when the recovered time is long enough, the signals received by the first signal receiving system are recovered to the initial state corresponding to the IV stage of the second harmonic wave in FIG. 2a, and the signals received by the first signal receiving system are processed to obtain the wafer defect detection result.

S5, turning off the detection light source 1 and the excitation light source 2, and ending the test.

Since the recovery state and the excited state are the opposite processes. Since no excitation light is active, the recovery phase signal change is only related to the material itself, and the defect level is already characterized in the excitation phase, the S4 step may not be present when detecting wafer defects.

However, in some special use scenarios, the recovery phase signal eventually fails to return to the original state, and this signal change is also used to characterize the specific sample electrical properties.

When detecting a wafer 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 is a wafer defect, if both the modulated optical signal and the second harmonic signal are normal, it is determined that there is no wafer defect, and if only one of the modulated optical signal and the second harmonic signal is abnormal, it may be a problem of the apparatus itself. Therefore, the wafer defect can be detected rapidly and accurately through mutual verification of the second harmonic signal and the modulated optical signal, and judgment errors caused by equipment faults are avoided.

For wafers processed through multiple processes, if the second harmonic signal is detected to be abnormal, and the modulated optical signal is also detected to be abnormal, the ion implantation condition is abnormal, and other influencing factors may exist to cause the second harmonic signal to be abnormal, such as oxide thickness, charge density change or interface state density change, etc.

If the second harmonic signal is abnormal, but the modulated optical signal does not detect the abnormality, the ion implantation condition is normal, but other influencing factors exist to cause the second harmonic signal to be abnormal, such as oxide thickness, charge density change or interface state density change, etc.

If the second harmonic signal is normal, but the modulated optical signal is abnormal, this indicates that the ion implantation condition is abnormal, and other influencing factors exist to cause the second harmonic signal which should be abnormal to be negatively influenced, such as oxide thickness, charge density change or interface state density change, etc.

If the second harmonic signal is normal and the modulated optical signal is also normal, it indicates that there is no wafer defect.

By mutual verification of the second harmonic signal and the modulated optical signal, whether the wafer defect exists or not can be judged, and the process conditions (such as ion implantation conditions) of wafer manufacturing and the changes (such as interface state density changes and the like) of the wafer before and after the manufacturing process can be further verified, so that the specific situation of the wafer defect and the specific process bringing the defect can be accurately judged.

Therefore, the wafer defect detection equipment disclosed by the application can be used for the defect condition of the interface or the surface of the wafer after single process processing, can also be used for the defect condition of the wafer after multi-process processing, can perform preliminary analysis on the normal or abnormal ion implantation conditions, and is convenient for quickly acquiring the specific process causing the wafer defect. In addition, the wafer defect detection equipment can mutually verify the detection result of the second harmonic signal and the modulated optical signal, and improves the accuracy of the detection result.

In the actual manufacturing process, an oxide layer, namely a silicon dioxide layer, is generated on the surface of a silicon wafer due to natural oxidation, and the principle of modulated light signal detection is that the ion implantation condition is reflected by measuring the reflectivity change caused by lattice damage of a silicon substrate, and the optical information carried by the final reflected light is actually the sum of a plurality of interface light reflection effects (such as air to surface oxide layer, surface oxide layer to substrate, substrate amorphous layer generated by high concentration ion implantation damage), namely the reflection light amplitude with refractive index gradient is coherently overlapped, so that the measurement correction of the reflectivity change of the actual silicon substrate needs to be considered by considering the existence of the oxide layer.

In actual production, the relationship between the second harmonic signal and the oxide layer thickness t is shown in fig. 5, and the oxide layer thickness t at this time can be determined by acquiring the second harmonic signal value under a specific condition, and the reflectivity without the oxide layer is obtained based on the oxide layer thickness t, thereby completing the correction step.

The second harmonic signal in the excited state is selected, and the second harmonic signal changes with time due to the excited state, and thus, the initial value (I0), the final value (If), or the average value (Iavg) is required to be identical to the second harmonic signal value used in the subsequent determination of the oxide layer thickness t in the curve shown in fig. 5 in order to obtain an accurate correction result.

The specific correction steps are as follows:

1. The second harmonic signals in the excited state corresponding to the different oxide layer thicknesses t are measured, the relation between the second harmonic signals and the oxide layer thicknesses t shown in fig. 5 is obtained, and the oxide layer thickness t is determined according to the specific second harmonic signals.

The second harmonic signal at this time may be an initial value (I0), a final value (If), or an average value (Iavg), and the relationship between the initial value (I0) of the second harmonic signal and the oxide layer thickness t is obtained based on the initial value (I0), the relationship between the final value (If) of the second harmonic signal and the oxide layer thickness t is obtained based on the final value (If), and the relationship between the average value (Iavg) of the second harmonic signal and the oxide layer thickness t is obtained based on the average value (Iavg).

Based on the initial value (I0), the corresponding oxide layer thickness t is obtained from 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, and the like, and based on the final value (If), the final value (If) is selected for the specific second harmonic signal.

2. Substituting the thickness t of the oxide layer into the following formula to obtain the refractive index n ₂ of the substrate;

3. Substituting the refractive index n ₂ of the substrate into the following formula to obtain the reflectivity r _without _oxide of the wafer to the second detection light when the oxide layer does not exist;

and r _without _oxide is directly related to the internal defect degree of the wafer, and the reflectivity of the wafer to the second detection light when no oxide layer exists can be further reflected by correcting the reflectivity of the silicon substrate.

Example 2

Unlike embodiment 1, the excitation light source 2 is divided into the first excitation light and the second excitation light by the third spectroscopic device 21, and the third spectroscopic device 21 is a spectroscope.

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. In generating the second harmonic signal, the second harmonic signal with a stronger signal is to be obtained and is to be received easily, which requires a relatively large power of the excitation light source 2, whereas the generation of the modulated light signal requires a relatively small power of the excitation light source 2. In the case of the common excitation light source, the setting of the power can only be prior to the second harmonic signal or the modulated optical signal, but cannot be achieved at the same time, for example, the power is set to be 50mw, and at the moment, both the second harmonic signal and the modulated optical signal can be obtained, but the signals are relatively weak.

In addition, the excitation light source is shared, so that the incidence positions of the laser light sources are identical, interference may exist between the second harmonic signal generated by excitation and the modulated light signal, and in order to avoid the problem caused by signal interference, the excitation light source is divided into two parts, and the two parts are respectively incident from different positions.

As shown in FIG. 3, a third light splitting device 21 is disposed on the incident light path of the excitation light source 2, where the third light splitting device 21 is a third light splitting device for splitting 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 is greater than or equal to 10:1. The first excitation light and the first detection light are matched, the second excitation light and the second detection light are matched, and 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 of embodiment 1, and are not described here again.

When the ratio of the power of the first excitation light to the power of 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, so that the requirements of the second harmonic signal and the modulated light signal can be met simultaneously. Of course, the ratio of the power of the first excitation light to the power of the second excitation light can be greater than 10:1, the power of the first excitation light is further increased, the power of the second excitation light is further reduced, and the detection of the second harmonic signal and the modulated light signal is facilitated.

The excitation positions of the first excitation light and the second excitation light on the sample 8 to be measured do not coincide. The excitation position interval of the first excitation light and the second excitation light on the sample 8 to be measured is [200 μm,1mm ]. The minimum excitation position interval of the first excitation light and the second excitation light on the sample 8 to be detected is 200 mu m, and the maximum excitation position interval is 1mm, and under the interval, the second harmonic signal and the modulated light signal do not interfere with each other, so that the influence on the detection result is avoided, and the accuracy of the detection result is ensured.

S2, turning on the detection light source 1, the first signal receiving system and the second signal receiving system 24, wherein the first signal receiving system and the second signal receiving system 24 receive constant signals, and the initial state is the moment;

S3, the detection light source 1 is kept on, the excitation light source 2 is turned on, the charge distribution of the sample 8 to be detected changes, the temperature at the detection point of the sample 8 to be detected gradually rises, signals received by the first signal receiving system and the second signal receiving system 24 change accordingly and are called an excited state, after the excited state is reached, the sample 8 to be detected is annealed, the signals received by the second signal receiving system 24 gradually decay to a stable state, when the charge distribution of the sample 8 to be detected reaches new dynamic balance and the temperature at the detection point of the sample 8 to be detected tends to be stable, the signals received by the first signal receiving system tend to be stable, and the signals received by the first signal receiving system and the second signal receiving system 24 are processed to obtain wafer defect detection results.

As a preferred embodiment, the wafer defect detection method further includes:

S4, after the signals received by the first signal receiving system tend to be stable, continuously keeping the detection light source 1 on, simultaneously turning off the excitation light source 2, enabling captured electrons to return to the substrate layer again for recombination, gradually recovering the signals received by the first signal receiving system, namely recovering the signals, and recovering the signals received by the first signal receiving system to the initial state when the recovering time is long enough;

s5, turning off the detection light source 1 and the excitation light source 2, and processing signals received by the first signal receiving system and the second signal receiving system 24 by the central processing unit, so that the test is finished.

Example 3

The excitation light source 2 is divided into the first excitation light and the second excitation light by the spectroscope, so that the problem caused by the fact that the power and the incidence position of the excitation light are completely consistent can be solved, but when the excitation light with different frequencies is required to be incident in the light path, two excitation light sources are required to be arranged. The number of the excitation light sources is two, so that the problems of frequency, power and incidence position brought by sharing the excitation light sources can be solved simultaneously.

Unlike embodiment 1, as shown in fig. 4, the number of excitation light sources is two, namely, the third excitation light 22 and the fourth excitation light 23 are each incident at 0 °, the incident paths of the third excitation light 22 and the first detection light are not coincident, and the incident paths of the fourth excitation light 23 and the second detection light are coincident. The incident light paths of the first detection light and the second detection light are the same as those of embodiment 1, and will not be described here again. The third excitation light 22 is used in combination with the first detection light and the fourth excitation light 23 is used in combination with the second detection light. When the second harmonic signal generated by the excitation of the first detection light and the modulated light signal generated by the excitation of the second detection light have different power requirements, two excitation lights are set for use in cooperation with the first detection light and the second detection light, and the excitation lights respectively use different powers, for example, the third excitation light 22 uses 50mw and 1w and the fourth excitation light 23 uses 5mw and 50 mw.

The material of the wafer to be tested can be silicon or silicon carbide, and when the material of the wafer to be tested is changed, the frequencies of the excitation light used by the first detection light and the excitation light used by the second detection light are different, so that the two excitation light sources can be selected to have different frequencies and powers by arranging the two excitation light sources.

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

Aiming at a second harmonic signal testing flow:

S1, setting test parameters, executing a test instruction by a central processing unit, moving a wafer to a test position by a wafer carrying platform 7 carrying a sample 8 to be tested, and adjusting the sample 8 to be tested to be positioned on a focal plane of test equipment by an automatic focusing system;

S2, turning on the detection light source 1 and the first signal receiving system, wherein the first signal receiving system receives a constant signal, and the first signal receiving system is in an initial state at the moment;

s3, keeping the detection light source 1 on, turning on the third excitation light 22, and gradually increasing the temperature of the detection point of the sample 8 to be detected, wherein the signals received by the first signal receiving system are changed along with the change of the charge distribution of the sample 8 to be detected, namely an excited state;

S4, continuously keeping the detection light source 1 on, simultaneously turning off the third excitation light 22, and returning the captured electrons to the substrate layer again for recombination, wherein the signal received by the first signal receiving system is gradually recovered, namely recovered state, and when the recovered time is long enough, the signal received by the first signal receiving system is recovered to the initial state;

s5, turning off the detection light source 1 and the third excitation light 22, and processing the signals received by the first signal receiving system by the central processing unit, so that the test is finished.

For a modulated optical signal test flow:

S1, setting test parameters, executing a test instruction by a central processing unit, moving a wafer carrying platform 7 carrying a sample 8 to be tested to a test position, and adjusting the sample 8 to be tested to be positioned on a focal plane of test equipment by an automatic focusing system;

S2, turning on the detection light source 1 and the second signal receiving system 24, wherein the second signal receiving system 24 receives a constant signal, and the state is an initial state at the moment;

S3, keeping the detection light source 1 on, turning on the fourth excitation light 23, changing the charge distribution of the sample 8 to be detected, gradually increasing the temperature at the detection point of the sample, and changing the signals received by the second signal receiving system 24, namely an excited state, wherein after the excited state is reached, the sample 8 to be detected is annealed, and the signals received by the second signal receiving system 24 are gradually attenuated to a stable state;

s4, turning off the detection light source 1 and the fourth excitation light 23, and processing signals received by the second signal receiving system 24 by the central processing unit, so that the test is finished.

Example 4

Unlike example 1, the power of the excitation light source 2 can be adjusted, i.e., the laser of the excitation light source 2 can be adjusted.

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

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

The testing process comprises the following steps:

S3, keeping the detection light source 1 on, turning on the excitation light source 2, setting the power of the excitation light source 2 to be a first excitation value, wherein the power of the excitation light source 2 is smaller than the excitation light source power required by generating a second harmonic signal, and the change of the charge distribution of the sample is not obvious because of the smaller power of the excitation light source 2, and the first signal receiving system has weak signals;

S4, keeping the detection light source 1 and the excitation light source 2 on, and simultaneously adjusting the power of the excitation light source 2 to be a second excitation value, wherein the range of the second excitation value is 50mw-1w, and the power of the excitation light source 2 is larger than or equal to the excitation light source power required by generating a second harmonic signal at the moment, so that the charge distribution of the sample 8 to be detected changes, and the signal received by the first signal receiving system changes along with the change, namely an excited state;

When the detection of the second detection light is completed, the excitation light source 2 is adjusted to a larger power to output excitation light so as to meet the excitation condition required by the first detection light, and even if the physical property change of the wafer surface due to the excitation process is larger at the moment, the detection result of the modulated light signal which is carried out in advance is not influenced.

The detection result of the second harmonic signal performed later can represent the electrical performance of the detection point of the sample 8 to be detected, but cannot be consistent with the detection result of the second harmonic signal performed directly. The reason is that the lower power has an influence on the second harmonic signal when the modulated optical signal is detected, and the annealing effect is generated on the wafer by the laser excitation, so that the second harmonic signal is further influenced. The inspector can pre-inspect the standard performance parameters or wafer second harmonic after standard process, namely, test the second harmonic signals at the position (the distance is closer, the inspection area is in the same state) near the test point, so as to obtain the second harmonic signals which are not annealed and can be used for comparison, and the second harmonic signals are used as standard values or reference values.

The result of the second harmonic signal detection after the modulated optical signal detection can be compared with the standard value or the reference value, and the difference reflects the electrical property difference of the wafer before and after annealing, namely the influence of annealing on the internal charge and the defect number is quantized.

Example 5

A computer device includes a processor and a memory;

the memory is used for storing the computer program and transmitting the computer program to the processor;

the processor is used for executing the wafer defect detection method according to instructions in the computer program.

Example 6

A computer readable storage medium storing a computer program for executing the above-described wafer defect detection method.

Example 7

A product comprising a computer program which, when run on a computer device, performs the wafer defect detection method described above.

The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention without requiring creative effort by one of ordinary skill in the art. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims

1. A wafer defect detection device, comprising:

A light source, the light source comprising 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 spectroscopic device, wherein the incident light path of the detection incident light is provided with the first spectroscopic device, and the first spectroscopic 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 enters the wafer at 0°;

A first signal receiving system, wherein the first detection light output path is provided with the first signal receiving system, and is used to receive a detection second harmonic signal emitted by the wafer under the action of the first detection light;

A second signal receiving system is provided in the outgoing optical 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, so as to detect the reflectivity of the wafer surface.

2. The wafer defect detection equipment as described in claim 1 is characterized in that it also includes a phase-locked amplifier, one end of which is connected to an excitation light source for pre-processing the excitation light emitted by the excitation light source into modulated light; the other end of the phase-locked amplifier is connected to a second signal receiving system for demodulating a signal received by the second signal receiving system, and the modulated light is a modulated light whose intensity has a time-varying characteristic.

3. The wafer defect detection equipment as described in claim 1 is characterized in that the first signal receiving system includes a polarization splitter, which is arranged on the outgoing optical path of the first detection light, and is used to separate the generated detection second harmonic signal into a P polarization signal and an S polarization signal. The first signal receiving system also includes a P signal receiving end and an S signal receiving end, which receive the P polarization signal and the S polarization signal respectively.

4. The wafer defect detection device according to claim 3 is characterized in that a first polarization element is arranged 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 noise of the second harmonic signal received by the S signal receiving end.

5. The wafer defect detection equipment as described in claim 1 is characterized in that the photon energy of the detection light source is lower than the bandgap width of any material in the wafer to be tested.

6. The wafer defect detection equipment as described in claim 1 is 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 equipment as described in claim 1 is characterized in that the wafer defect detection equipment also includes a central processing unit, which 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 to 7, characterized in that the wafer defect detection device further comprises a wafer stage, an input system and a display system;

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

The input system is used to receive input information from the user in human-computer interaction;

The display system is used to display the output information of the wafer defect detection equipment in human-computer interaction.

9. The wafer defect detection device as described in claim 8 is characterized in that the wafer defect detection device also includes an automatic focusing system for adjusting the focal plane of the excitation light source.

10. A wafer defect detection device, comprising:

A first spectroscopic device, wherein the incident light path of the detection incident light is provided with the first spectroscopic device, and 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 incident light path of the first detection light does not overlap with the incident light path of the excitation light source;

A third spectroscopic device is provided in the incident light path of the excitation light source, and is used to split the excitation light source into a first excitation light and a second excitation light, wherein the excitation positions of the first excitation light and the second excitation light on the sample to be measured do not overlap; the second detection light overlaps with the incident light path of the second excitation light, and is incident on the wafer at 0°;

11. The wafer defect detection equipment as described in claim 10 is characterized in that it also includes a phase-locked amplifier, one end of which is connected to an excitation light source for preprocessing the excitation light emitted by the excitation light source into modulated light; the other end of the phase-locked amplifier is connected to a second signal receiving system for demodulating a signal received by the second signal receiving system, and the modulated light is a modulated light whose intensity has a time-varying characteristic.

12. The wafer defect detection equipment as described in claim 10 is characterized in that the first signal receiving system includes a polarization splitter, which is arranged on the outgoing optical path of the first detection light, and is used to separate the generated detection second harmonic signal into a P polarization signal and an S polarization signal, and the first signal receiving system also includes a P signal receiving end and an S signal receiving end, which receive the P polarization signal and the S polarization signal respectively.

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

14. The wafer defect detection equipment as described in claim 10 is characterized in that the photon energy of the detection light source is lower than the bandgap width of any material in the wafer to be tested.

15 . The wafer defect detection device according to claim 10 , wherein a power ratio of the first excitation light to the second excitation light is ≥10:1.

16 . The wafer defect detection device according to claim 10 , wherein the interval between the excitation positions of the first excitation light and the second excitation light on the wafer to be tested is [200 μm, 1 mm].

17. The wafer defect detection device as described in claim 10 is characterized in that the wafer defect detection device also includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system, and is used to process 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 to 17, characterized in that the wafer defect detection device further comprises a wafer stage, an input system and a display system;

19. The wafer defect detection device as described in claim 18 is characterized in that the wafer defect detection device also includes an automatic focusing system for adjusting the focal plane of the excitation light source.

20. A wafer defect detection device, comprising:

A light source, the light source comprising a detection light source and an excitation light source, the detection light source emits a detection incident light, the excitation light source emits an excitation incident light, and the excitation light source comprises a third excitation light and a fourth excitation light;

A first spectroscopic device, wherein the incident light path of the detection incident light is provided with the first spectroscopic device, and 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 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, and the second detection light, the third excitation light, and the fourth excitation light are all incident on the wafer at 0°;

21. The wafer defect detection equipment as described in claim 20 is characterized in that it also includes a phase-locked amplifier, one end of which is connected to an excitation light source for pre-processing the excitation light emitted by the excitation light source into modulated light; the other end of the phase-locked amplifier is connected to a second signal receiving system for demodulating a signal received by the second signal receiving system, and the modulated light is a modulated light whose intensity has a time-varying characteristic.

22. The wafer defect detection equipment as described in claim 20 is characterized in that the first signal receiving system includes a polarization splitter, which is arranged on the output optical path of the first detection light, and is used to separate the generated detection second harmonic signal into a P polarization signal and an S polarization signal, and the first signal receiving system also includes a P signal receiving end and an S signal receiving end, which receive the P polarization signal and the S polarization signal respectively.

23. The wafer defect detection device according to claim 22, characterized in that a first polarization element is provided on the incident light path of the first detection light, for adjusting the polarization direction of the first detection light to P polarization or S polarization, and when the first polarization element adjusts the polarization direction of the first detection light to P polarization, an S signal receiving end is used to reduce noise of the second harmonic signal received by the P signal receiving end, or,

24. The wafer defect detection equipment as described in claim 20 is characterized in that the photon energy of the detection light source is lower than the bandgap width of any material in the wafer to be tested.

25. The wafer defect detection device as described in claim 20 is characterized in that the wafer defect detection device also includes a central processing unit, which is connected to the first signal receiving system and the second signal receiving system, and is used to process 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 to 25, characterized in that the wafer defect detection device further comprises a wafer stage, an input system and a display system;

27. The wafer defect detection equipment as described in claim 26 is characterized in that it also includes an automatic focusing system for adjusting the focal plane of the excitation light source.

28. A wafer defect detection method, using the wafer defect detection device according to any one of claims 1 to 5 or 7 to 27, characterized in that it comprises the following steps:

S1, turn on the detection light source, the first signal receiving system and the second signal receiving system receive the signals stimulated by the first detection light and the second detection light respectively, at this time the signals are constant and are in the initial state;

S2. Keep the detection light source turned on, and turn on the excitation light source at the same time. The charge distribution of the sample to be tested 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 are in an excited state. After reaching the excited state, the sample to be tested is annealed, 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 tested 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. The signals received by the first signal receiving system and the second signal receiving system are processed to obtain wafer defect detection results.

29. The wafer defect detection method according to claim 28, further comprising:

S31. After the signal received by the first signal receiving system tends to be stable, the detection light source continues to be turned on, and the excitation light source is turned off. The captured electrons return to the substrate layer to recombine, and the signal received by the first signal receiving system gradually recovers, which is called a 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. The wafer defect detection method according to claim 28, further comprising:

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 as claimed in claim 30, characterized in that the correction step is:

S321, according to the relationship between the second harmonic signal and the oxide layer thickness t, obtaining the oxide layer thickness t when a specific second harmonic signal occurs;

S322, substituting the oxide layer thickness t into the following formula to obtain the substrate refractive index n ₂ ;

Where r _{with oxide} is the reflectivity of the wafer to the second detection light when there is an oxide layer; r ₀ is the reflectivity of the oxide layer surface, r ₁ is the reflectivity of the interface between the oxide layer and the substrate, n ₁ is the refractive index of the oxide layer, and n ₂ is the refractive index of the substrate;

S323, substituting the substrate refractive index _n2 into the following formula to obtain the reflectivity rwithoutoxide of the wafer to the second detection light when there is no _oxide layer;

.

32. A wafer defect detection method, using the wafer defect detection device according to claim 6, characterized in that it comprises the following steps:

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;

S2, keep the detection light source turned on, turn on the excitation light source at the same time, adjust the power of the excitation light source to a first excitation value, the first excitation value is less than the excitation light source power 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 an excited state; after reaching the excited state, the sample to be tested is annealed, and the signal received by the second signal receiving system gradually decays to a stable state;

S3, continue to keep the detection light source turned on, and at the same time adjust the power of the excitation light source to a second excitation value, wherein the second excitation value is greater than or equal to the excitation light source power required to generate a second harmonic signal. At this time, the charge distribution of the sample 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 to be tested reaches a new dynamic equilibrium, the signal received by the first signal receiving system tends to be stable accordingly;

S4. Process the signals received by the first signal receiving system and the second signal receiving system to obtain wafer defect detection results.

33. The wafer defect detection method as described in claim 32 is characterized in that the first excitation value is ≥5mw and <50mw, and the second excitation value is ≥50mw and ≤1w.

34. The wafer defect detection method according to claim 32, further comprising:

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 comprises:

S51, according to the relationship between the second harmonic signal and the oxide layer thickness t, obtaining the oxide layer thickness t when a specific second harmonic signal occurs;

S52, substituting the oxide layer thickness t into the following formula to obtain the substrate refractive index n ₂ ;

S53, substituting the substrate refractive index _n2 into the following formula to obtain the reflectivity rwithoutoxide of the wafer to the second detection light when there is no _oxide layer;

.

36. A computer device, comprising: 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 described in 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 described in any one of claims 28-31 or claims 32-35.

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