Wafer detection system capable of adjusting wavelength and intensity of detection light source in real time

Abstract

The invention provides a wafer detection system capable of adjusting the wavelength and intensity of a detection light source in real time, which is applied to the technical field of wafer detection and is characterized by comprising a broadband light source, a light source adjusting module and an imaging module, the light source adjusting module comprises an acousto-optic element, an optical filter, a total reflective mirror and an overturning mirror, an optical signal output by the wide-spectrum light source is divided into zero-order transmission light and first-order diffraction light after passing through the acousto-optic element, the first-order diffraction light is reflected by the total reflective mirror after being subjected to wavelength selection through the optical filter, and the overturning mirror is used for overturning the zero-order transmission light and the first-order diffraction light. The overturning mirror is used for switching the zero-order transmission light or the light reflected by the total reflection mirror to serve as a detection light source to be incident to the imaging module, the detection light source is reflected and focused to the surface of a wafer to be detected through the imaging module, and an optical signal reflected by the surface of the wafer to be detected is imaged through the imaging module. The light source in the detection system can be adjusted more flexibly, so that the wafer detection effect is better.

Description

Technical Field

[0001] The present application relates to the field of wafer detection technology, and in particular to a wafer detection system in which the wavelength and intensity of a detection light source can be adjusted in real time. Background Art

[0002] After different processes in the wafer manufacturing process, dimension measurement and defect detection are required. With the development of new materials and the continuous reduction of pattern size, the demand for wafer detection is also constantly upgrading. Optimizing the wavelength and intensity of the detection light source is an effective way to optimize the wafer detection effect.

[0003] Traditional wafer inspection systems select the detection wavelength by adding a bandpass filter to the light source module. In order to meet various process requirements, multiple bandpass filters are usually installed on a rotating wheel, and the detection wavelength is selected by rotating the rotating wheel. In addition, in order to adjust the intensity of the detection light source, a variable neutral filter needs to be added to the light source module, and the intensity of the detection light source is adjusted by rotating the neutral filter. There are some problems with existing wafer inspection systems, such as: the number of filters installed on the rotating wheel is limited, and the number of selectable detection light source wavelengths is limited; new wavelengths cannot be selected after the filters are fixed; selecting filters by rotating the rotating wheel is slow and inefficient; the wavelength and intensity of the detection light source need to be adjusted by different motors, and the system is complex and inconvenient to operate.

[0004] Based on this, a new technical solution is needed. Summary of the invention

[0005] In view of this, the embodiments of the present specification provide a wafer inspection system with real-time adjustable wavelength and intensity of the detection light source. By adjusting the frequency, power and aperture of the pinhole diaphragm loaded on the acousto-optic deflector, the wavelength and intensity of the system's detection light source are changed. The light source in the inspection system can be adjusted more flexibly, thereby improving the wafer inspection effect.

[0006] The embodiments of this specification provide the following technical solutions:

[0007] The embodiment of this specification provides a wafer inspection system in which the wavelength and intensity of a detection light source can be adjusted in real time, characterized in that it includes: a broadband light source, a light source adjustment module, and an imaging module;

[0008] The light source adjustment module includes an acousto-optic element, an optical filter, a total reflection mirror, and a flip mirror. The optical signal output by the wide-spectrum light source is divided into zero-order transmitted light and first-order diffracted light after passing through the acousto-optic element. The first-order diffracted light is reflected by the total reflection mirror after wavelength selection by the optical filter. The flip mirror is used to switch the zero-order transmitted light or the light reflected by the total reflection mirror as a detection light source to be incident on the imaging module. The detection light source is reflected and focused to the surface of the wafer to be tested by the imaging module, and the optical signal reflected by the surface of the wafer to be tested is then imaged by the imaging module.

[0009] In some embodiments, the frequency of the driving signal applied to the acousto-optic element is continuously adjustable.

[0010] In some embodiments, the power of the driving signal applied to the acousto-optic element is continuously adjustable.

[0011] In some embodiments, when the acousto-optic element is loaded with a plurality of driving signals of different frequencies, the detection light source is a superposition of a plurality of lights of different wavelengths.

[0012] In some embodiments, the optical filter is a pinhole stop or a spatial filter.

[0013] In some embodiments, the aperture stop has an adjustable aperture.

[0014] In some embodiments, the flip mirror has a first state and a second state. When the flip mirror is in the first state, the zero-order transmitted light is directly incident on the imaging module as a detection light source. When the flip mirror is in the second state, the light reflected by the total reflection mirror is reflected by the flip mirror and then incident on the imaging module as a detection light source.

[0015] In some embodiments, the imaging module includes a beam splitter, an objective lens, a lens, and a camera. The detection light source is reflected and focused onto the surface of the wafer to be tested by the beam splitter and the objective lens. The light signal reflected from the surface of the wafer to be tested passes through the objective lens and the beam splitter and then is focused onto the camera for imaging by the lens.

[0016] In some embodiments, the camera is an area scan camera or a line scan camera.

[0017] In some embodiments, the acousto-optic element is replaced by an acousto-optic deflector or an acousto-optic tunable filter.

[0018] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0019] 1. This application can change the wavelength and intensity of the system detection light source by adjusting the frequency, power and aperture of the small aperture loaded on the acousto-optic deflector;

[0020] 2. The light source adjustment module can convert the broad-spectrum light source into a monochromatic detection light source or a detection light source with multiple monochromatic lights superimposed;

[0021] 3. The light source adjustment module can adjust the wavelength and intensity of the monochromatic detection light source in real time;

[0022] 4. The light source adjustment module can switch the detection light source to monochromatic light or broadband light;

[0023] 5. The detection light source can be adjusted quickly and the detection efficiency is higher;

[0024] 6. The wafer inspection effect is more accurate and can be applied to wafer inspection of different materials and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 is a schematic diagram of the wafer inspection system in this application;

[0027] Figure numerals: 1-broad-spectrum light source, 2-acoustic-optic deflector, 3-pinhole aperture, 4-total reflection mirror, 5-flip mirror, 6-beam splitter, 7-objective lens, 8-wafer, 9-lens, 10-camera. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0029] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0030] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0032] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0033] Based on this, this specification embodiment proposes a processing solution: Figure 1 As shown, an embodiment of the present specification provides a wafer inspection system with real-time adjustable wavelength and intensity of a detection light source, including: a broadband light source 1, a light source adjustment module, a light source input module, and an imaging module.

[0034] The light source adjustment module includes an acousto-optic deflector 2, a pinhole aperture 3, a total reflection mirror 4, and a flip mirror 5. Among them, after the wide-spectrum light source 1 passes through the acousto-optic deflector 2, it is divided into zero-order transmitted light and first-order diffracted light (indicated by dotted lines). Each wavelength component of the wide-spectrum light in the zero-order transmitted light propagates along the direction of the incident light, and the first-order diffracted light is reflected by the total reflection mirror 4 after wavelength selection by the pinhole aperture 3. One wavelength of light in the first-order diffracted light can pass through the pinhole aperture 3, and the remaining wavelengths of light are blocked by the pinhole aperture 3. The aperture of the pinhole aperture 3 determines the bandwidth of the transmitted light. The flip mirror is used to switch the zero-order transmitted light or the light reflected by the total reflection mirror as the detection light source to be incident on the imaging module. The detection light source is reflected and focused on the wafer 8 to be tested by the imaging module, and the signal light reflected from the surface of the wafer 8 to be tested is then imaged by the imaging module.

[0035] The acousto-optic deflector 2 generates mechanical waves in media such as transparent glass and crystal, causing periodic changes in the refractive index to become a phase-type diffraction grating. If a laser beam is incident on the medium, the laser beam will diffract, and the intensity and direction of the diffracted light will change with the intensity and wavelength of the mechanical wave.

[0036] In some embodiments, the frequency of the driving signal loaded by the acousto-optic element is continuously adjustable. By adjusting the frequency of the driving signal to change the wavelength of the first-order diffraction light, the wavelength of the detection light source can be adjusted in real time through the acousto-optic deflector. The adjustment speed is fast, the detection efficiency is high, and the complexity of the system is effectively reduced.

[0037] In some embodiments, the power of the driving signal loaded on the acousto-optic element is continuously adjustable, and the diffraction efficiency is adjusted by adjusting the power of the driving signal loaded on the acousto-optic deflector 2, thereby adjusting the intensity of the first-order diffracted light and the zero-order transmitted light, that is, adjusting the detection light intensity.

[0038] In some embodiments, when the diffraction efficiency of the acousto-optic deflector 2 is 100%, there is only the first-order diffracted light with the maximum intensity, and when the diffraction efficiency is 0, there is only the zero-order transmitted light with the maximum intensity.

[0039] Since the wavelength and intensity of the detection light source are adjusted by adjusting the frequency and power of the driving signal loaded on the acousto-optic deflector 2, the adjustment speed is much higher than the traditional mechanical adjustment method.

[0040] In some embodiments, when the acousto-optic element is loaded with multiple driving signals of different frequencies, the detection light source is a superposition of multiple lights of different wavelengths. By changing the frequency and number of driving signals, the wavelength of the detection light can be flexibly optimized, thereby making the wafer detection more accurate and able to meet the detection needs of more types of wafers.

[0041] In some embodiments, the optical filter is a pinhole stop or a spatial filter.

[0042] In some embodiments, the pinhole diaphragm has an adjustable aperture. The larger the diameter of the pinhole diaphragm 3 is, the wider the bandwidth of the first-order diffraction light can be. Combined with the adjustment function of the acousto-optic deflector 2, it can generate detection light sources with more wavelengths, which is easy to adjust and has a fast adjustment speed.

[0043] In some embodiments, one wavelength of the first-order diffraction light can pass through the pinhole aperture 3, so that the detection light source is a single monochromatic light.

[0044] In some embodiments, the flip mirror has a first state and a second state. When the flip mirror is in the first state, the flip mirror is located below the zero-order transmitted light and parallel to the zero-order transmitted light. At this time, the first-order diffraction light cannot be reflected. The zero-order transmitted light is directly incident on the imaging module as a detection light source. When the flip mirror is in the second state, the flip mirror is tilted at a certain angle to block the zero-order transmitted light. The light reflected by the total reflection mirror is reflected by the flip mirror and then incident on the imaging module as a detection light source. The intensity of the detection light source will not decrease when passing through the flip mirror 5.

[0045] In some embodiments, when the zero-order transmitted light is used as the detection light source, the detection light source is broad-spectrum light; when the first-order diffraction light is used as the detection light source, the detection light source is monochromatic light.

[0046] In some embodiments, the imaging module includes a beam splitter 6, an objective lens 7, a lens 9, and a camera 10. The detection light source is reflected and focused by the beam splitter 6 and the objective lens 7 to the surface of the wafer 8 to be tested, and then the beam splitter 6 is focused by the lens 9 to the camera 10 for imaging.

[0047] In some embodiments, it is characterized in that the camera 10 is an area array camera or a line array camera, which can effectively ensure the accuracy of imaging of the inspection results of the wafer 8.

[0048] In some embodiments, the acousto-optic deflector 2 may also be replaced by an acousto-optic tunable filter or other suitable acousto-optic elements, which may be replaced according to actual usage.

[0049] In some embodiments, the pinhole aperture 3 can be replaced by a spatial filter or other suitable optical filters, which can be replaced according to actual usage.

[0050] In some embodiments, the present solution can be implemented in free space or using optical fiber.

[0051] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0052] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A wafer inspection system with real-time adjustable wavelength and intensity of the detection light source, characterized in that: include: Broad-spectrum light source, light source adjustment module, imaging module; The light source adjustment module includes an acousto-optic element, an optical filter, a total reflection mirror, and a flip mirror. The optical signal output by the wide-spectrum light source is divided into zero-order transmitted light and first-order diffracted light after passing through the acousto-optic element. The first-order diffracted light is reflected by the total reflection mirror after wavelength selection by the optical filter. The flip mirror is used to switch the zero-order transmitted light or the light reflected by the total reflection mirror as a detection light source to be incident on the imaging module. The detection light source is reflected and focused to the surface of the wafer to be tested by the imaging module, and the optical signal reflected by the surface of the wafer to be tested is then imaged by the imaging module.

2. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: The frequency of the driving signal applied to the acousto-optic element is continuously adjustable.

3. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 2, characterized in that: The power of the driving signal applied to the acousto-optic element is continuously adjustable.

4. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: When the acousto-optic element is loaded with a plurality of driving signals of different frequencies, the detection light source is a superposition of a plurality of lights of different wavelengths.

5. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: The optical filter is a pinhole aperture or a spatial filter.

6. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 5, characterized in that: The aperture stop has an adjustable aperture.

7. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: The flip mirror has a first state and a second state. When the flip mirror is in the first state, the zero-order transmitted light is directly incident on the imaging module as a detection light source. When the flip mirror is in the second state, the light reflected by the total reflection mirror is reflected by the flip mirror and then incident on the imaging module as a detection light source.

8. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: The imaging module includes a beam splitter, an objective lens, a lens, and a camera. The detection light source is reflected and focused to the surface of the wafer to be tested by the beam splitter and the objective lens. The light signal reflected from the surface of the wafer to be tested passes through the objective lens and the beam splitter and is focused to the camera for imaging by the lens.

9. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 8, characterized in that: The camera is an area array camera or a line array camera.

10. The wafer inspection system with real-time adjustable wavelength and intensity of the inspection light source according to claim 1, characterized in that: The acousto-optic element is replaced by an acousto-optic deflector or an acousto-optic tunable filter.

Images