Charged particle inspection system and method using multi-wavelength charge controller

Abstract

An apparatus for inspecting a substrate and a method of inspecting a substrate, wherein a charged particle beam is arranged to impinge on a portion of the substrate and a first light beam having a first wavelength and a second light beam having a second wavelength different from the first wavelength are also arranged to impinge on the portion of the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application 62 / 925,320, filed October 24, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to charged particle inspection systems and methods that utilize a charge controller to control electrical and / or thermal properties at portions of an inspected item. Background Art

[0004] Improvements in semiconductor manufacturing technology have allowed for increased density of integrated circuits, enabling the packaging of more transistors onto a given wafer surface area or within a given volume to form semiconductor devices. This increased transistor density has led to the need for systems and methods that provide higher-resolution wafer inspection. In particular, defects can occur at various stages of the semiconductor device manufacturing process. Accurately and efficiently identifying any such defects as early as possible is crucial.

[0005] Typically, the process used to manufacture semiconductor devices involves forming layers of various materials on or in a substrate for each semiconductor device; performing photoprocessing, masking, and forming circuit patterns on the semiconductor device; and removing or etching portions of the layers to form the semiconductor device. Such semiconductor devices are manufactured by repeating these and other operations for each device on a semiconductor wafer. Improved manufacturing techniques have enabled microfabrication, resulting in features that are difficult to discern with most observation tools. For this reason, charged particle beam detection systems, such as scanning electron microscopes (SEMs), electron beam detectors, and focused ion beam (FIB) systems, have been used.

[0006] Electron beam (e-beam) inspection is performed by scanning an electron beam over a surface pattern of a device formed on a substrate and collecting secondary electrons emitted from the surface pattern of the scanned device as an inspection signal. The signal is processed and represented in grayscale to produce an image of the surface pattern of the scanned device. The patterned surface contains pattern features that form electronic devices or are directly / indirectly electrically connected to devices within the substrate. The obtained image, displayed in grayscale contrast, represents the difference in charged voltage associated with the devices, connections, and materials. Therefore, the image is also called a voltage contrast (VC) image. Abnormal grayscale levels or abnormal VC are detected to identify defective devices or connections. For example, if a bright grayscale level appears where a darker grayscale level should be observed, a bright voltage contrast (BVC) defect is considered to be present. On the other hand, if a dark grayscale level appears where a brighter grayscale level should be observed, a dark voltage contrast (DVC) defect is considered to be present.

[0007] As the electron beam scans across the surface pattern of a device, charges may be induced and accumulate on the device. The resulting charges can be negative or positive, depending on the electron beam conditions used (landing energy, beam current, etc.) and the surface pattern material. In particular, for electron beam (e-beam) inspection tools designed to meet higher beam current requirements, the quality of the acquired images will be degraded due to the charge accumulated on the wafer sample surface. This makes it more difficult to identify critical defects.

[0008] To circumvent this problem, charge regulation techniques are implemented to adjust the charge conditions at the wafer surface. One such technique uses laser radiation to illuminate the wafer surface, thereby controlling local charging through photoconductivity and / or the photoelectric effect. For example, the beam can induce a photocurrent or stimulate a leakage current, causing electrons from the ground or substrate to migrate to the inspection location and neutralize the positive charge accumulated on the scanning surface of the device. This helps to drain the positive charge accumulated on the scanned device. See, for example, Y. Zhao et al., Beam Enhanced Defect Detection Using Electron Beam Inspection Tools, 2008 International Symposium on Semiconductor Manufacturing (ISSM), Tokyo, Japan, pp. 258-260, which is incorporated herein by reference. Summary of the Invention

[0009] The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of the embodiments. This summary is not an extensive overview of all contemplated embodiments and is not intended to identify important or critical elements of all embodiments, nor to delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

[0010] According to one aspect of the embodiments, an apparatus for inspecting a substrate is disclosed, the apparatus comprising: a charged particle beam source configured to project a charged particle beam onto a portion of a substrate; a first light source configured to project a first light beam having a first wavelength onto the portion of the substrate; and a second light source configured to project a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate. The charged particle beam source may comprise an electron beam source. The first light source may comprise a first laser configured to generate the first light beam, and the second light source may comprise a second laser configured to generate the second light beam. The first wavelength may be selected to penetrate the portion of the substrate to a first depth, and the second wavelength may be selected to penetrate the portion of the substrate to a second depth different from the first depth. The first wavelength may be selected to generate a thermal effect in the portion of the substrate, and the second wavelength may be selected to modify electrical properties in the portion of the substrate. The first wavelength may be selected to generate a thermal effect in a portion of the wafer at a first depth, and the second wavelength may be selected to modify electrical properties in a portion of the wafer at a second depth different from the first depth. The apparatus may further comprise a beam combiner configured to combine the first and second light beams into a single beam. The beam combiner may comprise a dichroic mirror. The beam combiner may include a trichroic prism.

[0011] According to another aspect of the present invention, a charged particle beam imaging apparatus for imaging a portion of a substrate is disclosed. The apparatus includes: a charged particle beam source; a charged particle optical system configured to focus the beam onto the portion of the substrate; and an electromagnetic radiation optical system adapted to generate a first light beam having a first wavelength and a second light beam having a second wavelength different from the first wavelength, and to focus the first and second light beams onto the portion of the substrate. The charged particle beam source may include an electron beam source. The electromagnetic radiation optical system may include a first laser configured to generate the first light beam and a second laser configured to generate the second light beam. The first wavelength may be selected to penetrate the portion of the substrate to a first depth, and the second wavelength may be selected to penetrate the portion of the substrate to a second depth different from the first depth. The first wavelength may be selected to generate a thermal effect in the portion of the substrate, and the second wavelength may be selected to modify electrical properties in the portion of the substrate. The first wavelength may be selected to generate a thermal effect in the portion of the substrate at a first depth, and the second wavelength may be selected to modify electrical properties in the portion of the substrate at a second depth different from the first depth. The apparatus may also include a beam combiner configured to combine the first and second light beams into a single beam. The beam combiner may include a dichroic mirror. The beam combiner may include a trichroic prism.

[0012] According to another aspect of the embodiments, a method for inspecting a substrate is disclosed, the method comprising the steps of: projecting a charged particle beam onto a portion of the substrate; projecting a first light beam having a first wavelength onto the portion of the substrate; and projecting a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate. The step of projecting the charged particle beam onto the portion of the substrate may be performed using an electron beam source. The steps of projecting the first light beam having the first wavelength onto the portion of the substrate and projecting the second light beam having the second wavelength different from the first wavelength onto the portion of the substrate may be performed simultaneously. The step of projecting the first light beam having the first wavelength onto the portion of the substrate may be performed using a first laser, and the step of projecting the second light beam having the second wavelength different from the first wavelength onto the portion of the substrate may be performed using a second laser. The first wavelength may be selected to penetrate the portion of the substrate to a first depth, and the second wavelength may be selected to penetrate the portion of the substrate to a second depth different from the first depth. The first wavelength may be selected to generate a thermal effect in the portion of the substrate, and the second wavelength may be selected to modify electrical properties in the portion of the substrate. The first wavelength may be selected to generate a thermal effect in a portion of the wafer at a first depth, and the second wavelength may be selected to modify electrical properties in a portion of the wafer at a second depth different from the first depth. The method may further comprise the step of combining the first light beam and the second light beam into a single light beam. The combining step may be performed using at least one dichroic mirror. The combining step may be performed using at least one trichroic prism.

[0013] Further embodiments, features, and advantages of the present invention, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate by way of example and not limitation, the methods and systems of embodiments of the present invention. Together with the detailed description, the drawings further serve to explain and enable those skilled in the relevant art to make and use the methods and systems presented herein. In the drawings, like reference numerals indicate identical or functionally similar elements.

[0015] Figure 1 is a schematic diagram of a charged particle beam system, such as may be used in accordance with aspects of the embodiments disclosed herein.

[0016] Figure 2 Illustrated is an embodiment of a charged particle beam system incorporating a charge regulation module according to aspects of the embodiments disclosed herein.

[0017] Figure 3A is a conceptual diagram illustrating the concept that two lights having different wavelengths penetrate into different depths in a substrate.

[0018] Figure 3B is a conceptual diagram illustrating the concept that two types of light with different wavelengths affect different properties of a substrate.

[0019] Figure 4 is a diagram showing an arrangement of a multi-wavelength light source according to an aspect of the embodiment.

[0020] Figure 5 is a diagram showing an arrangement of a multi-wavelength light source according to an aspect of the embodiment.

[0021] Figure 6 is a diagram showing an arrangement of a multi-wavelength light source according to an aspect of the embodiment.

[0022] Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to the specific embodiments described herein. These embodiments are presented herein for illustrative purposes only. Based on the teachings contained herein, other embodiments will be apparent to those skilled in the relevant art. DETAILED DESCRIPTION

[0023] Various embodiments will now be described with reference to the accompanying drawings, in which the same reference numerals are used throughout to refer to the same elements. In the following description, for the purpose of explanation, many specific details are set forth to facilitate a thorough understanding of one or more embodiments. However, in some or all cases, it will be apparent that any embodiment described below may be practiced without adopting the specific design details described below. In other cases, well-known structures and devices are shown in block diagram form to facilitate description of one or more embodiments. A simplified overview of one or more embodiments is presented below to provide a basic understanding of the embodiments. This overview is not an extensive overview of all contemplated embodiments and is not intended to identify the important or key elements of all embodiments, nor is it intended to describe the scope of any or all embodiments.

[0024] Examples of charged particle inspection systems include SEM (scanning electron microscope), TEM (tunneling electron microscope), STEM (scanning tunneling electron microscope), AFM (atomic force microscope), or FIB (focused ion beam) instruments. For defect inspection of silicon wafers, commercial electron beam inspection tools most commonly use SEMs. Therefore, the following discussion of preferred embodiments will use SEMs as an example, but it should be understood that the concepts disclosed herein may also be applicable to other types of charged particle inspection systems.

[0025] As noted above, electronic devices are made up of circuits formed on a piece of silicon called a substrate. Many circuits can be formed together on the same piece of silicon, called an integrated circuit or IC. The size of these circuits has been significantly reduced so that more circuits can be installed on the substrate. For example, the IC chips in a smartphone can be as small as a thumbnail Figure 1

[0026] Manufacturing these tiny ICs is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. Even a mistake in one step can result in a defective finished IC, making it useless. Therefore, one goal of the manufacturing process is to quickly and reliably identify such defects.

[0027] Therefore, the chip circuit structures are typically inspected at various stages of their formation. The inspection can be performed using a scanning electron microscope (SEM), also referred to herein as an e-beam inspection system. The SEM can be used to image, in effect to “take a picture of, these tiny structures. This image can be used to determine whether the structure was formed correctly and in the correct location.

[0028] As the name implies, the SEM uses an electron beam, as such a beam can be used to observe structures that are too small to be seen by a microscope using light. However, the electrons in the electron beam can cause charge to build up on the surface of the substrate. This can interfere with obtaining a useful image. In addition, for some devices, part of the circuit can be located below the surface of the substrate. It can be beneficial to be able to control physical properties such as electrical or thermal properties of the substrate and at different depths within the substrate.

[0029] One of the several disclosures in this application is a system and method in which the portion of the substrate that is subjected to the electron beam is also subjected to two light beams having different wavelengths. This provides the ability to control physical properties such as electrical or thermal properties of the substrate and at different depths within the substrate. Of course, this is only a general description, and the specific details will be set forth more completely and accurately in the following.

[0030] SEM-based e-beam inspection tools are used in the semiconductor industry to inspect the structures formed on the substrate. These tools are used to detect defects in the structures, such as missing or extra material, or misshapen structures. Figure 1 ​The SEM 100 includes an electron gun and a column, where the electron gun includes a tip 101, a Schottky suppressor electrode 102, an anode 103, an optional Coulomb aperture 104, and a condenser lens 110. The tip 101, which emits a primary electron beam 190, can be a high-temperature Schottky point cathode, which is a ZrO / W Schottky electrode. The Schottky suppressor electrode 102 provides a virtual source for the primary electron beam 190. The anode electrode 103 provides an electric field to extract electrons from the tip 101. The primary electron beam 190 then passes through the optional Coulomb aperture 104 to reduce aberrations caused by Coulomb forces. The primary electron beam is then condensed by the condenser lens 110. Figure 1 The condenser lens 110 in the SEM 100 is an electrostatic lens, but one or more magnetic lenses can also be employed in the SEM 100 for any person skilled in the art.

[0031] The column in the SEM 100 includes a beam blanker 120, a detector 170, two deflectors 141 and 142, and an objective lens 130. The beam blanker 120 includes a plurality of apertures to allow a user to select an appropriate beam current for the primary electron beam. The primary electron beam is then focused by the objective lens 130 onto a wafer sample 1 supported by a stage 10. The sample 1 can be a mask for a lithography process, a silicon wafer, a GaAs wafer, a SiC wafer, or any other substrate used for semiconductor processes. As used herein, the term "substrate" is intended to encompass all of these structures. Figure 1 The objective lens 130 in the SEM 100 is a magnetic lens that includes a coil 132 surrounded by a magnetic yoke 131. The two deflectors 141 and 142 deflect the primary electron beam 190 to scan it across the wafer sample 1. An electrode 150 below the objective lens 130 can provide a retarding or immersion electric field for the primary electron beam 190. An electric potential can be applied to the stage 10 so that the landing energy of the primary electron beam 190 can be adjusted or controlled. Figure 1 The objective lens 130 shown in the SEM 100 can be of the type typically used in SEMs, but variant designs and structures for specific purposes can also be applied, such as SORIL lenses, for large FOV (field of view) inspection, as disclosed in U.S. Patent No. 6,392,231.

[0032] Figure 2An arrangement for providing charge regulation is shown, in which a laser 320 illuminates a portion of a sample 1 with electromagnetic radiation. The electromagnetic radiation is then reflected to a detector 325, which may be a CCD (charge-coupled device) or CMOS (complementary metal oxide semiconductor) sensor, among others. After the detector 325 receives the signal from the laser 320, the controller 300 detects the beam spot position on the surface of the sample 1, calculates the predetermined location for irradiation by the primary electron beam 190, and drives the laser 320 to irradiate the beam spot to the predetermined location via the transmission medium 310. The SEM 100, laser 210, detector 325, wafer sample 1, and stage 10 are all within the vacuum chamber 200. The controller 300, which may be a computer or an ASIC (application-specific integrated circuit), is located outside the vacuum chamber 200.

[0033] As described above, a charge controller generates a laser beam and projects the laser light toward the center of the electron beam at the sample. Laser radiation is typically applied to the sample surface to help control charge accumulation on the sample during electron beam inspection. This laser beam modifies the electron extraction rate of the material, for example, by generating electrical effects (surface plasmons, electric field changes) in the material or thermal effects (thermal / phonon vibrations) in the crystal lattice of the semiconductor material in the sample. Thus, through the interaction of photons with the semiconductor material, the signal-to-noise ratio (S / N) of the signal generated during electron beam investigation can be improved.

[0034] The ease with which electromagnetic radiation interacts with a material depends, in part, on the wavelength of the electromagnetic radiation. According to one aspect of an embodiment, multiple electromagnetic radiation sources are used, each with a different wavelength. This allows for a wider range of interactions with the material, both in terms of interaction depth and interaction type. For example, electromagnetic radiation having a first wavelength can have a different penetration depth than electromagnetic radiation having a second wavelength different from the first wavelength. As another example, electromagnetic radiation having a first wavelength can interact with a material primarily through an electrical effect, while electromagnetic radiation having a second wavelength different from the first wavelength can interact with the material primarily through a thermal effect. Thus, a charge controller with multiple wavelength sources offers the possibility of a whole new range of inspection techniques.

[0035] As mentioned above, the purpose of a charge controller is to improve the signal-to-noise ratio of the signal generated during electron beam investigation or inspection, and these terms are used synonymously herein. In other words, the charge controller is used to increase the contrast between devices in a sample that have defects and those that do not.

[0036] Because different parts of a logic / memory device can be made of different materials with varying structures, it's desirable for the charge controller to be effective at different depths. This requires the charge controller beam to penetrate deep into the material and be absorbed. In other words, to improve the signal-to-noise ratio at different parts of the logic / memory device, multiple beams with different wavelengths can be used, allowing the charge controller to operate both shallowly and deep within the wafer where sufficient photon energy is absorbed.

[0037] Light beams with different wavelengths have different penetration depths (travel lengths) in the material. p According to the relation δ p =λ0 / (4πκ), where λ0 is the wavelength of light and κ is the extinction coefficient of the material. Therefore, longer wavelengths of light have a greater penetration depth. A longer penetration depth means that the light's energy is less strongly absorbed by the material. It should be noted that the term "light" is used here to refer to the entire electromagnetic spectrum, whether visible to the human eye or not, and can include infrared, ultraviolet, X-rays, gamma rays, or radiofrequency electromagnetic radiation, among others.

[0038] exist Figure 3A , a portion of a sample 1 is shown with different structures 400, 401, 402, etc. at different depths. A short wavelength beam 410 interacts with structure 402 at a first depth A. A longer wavelength beam 420 is less strongly absorbed and interacts with structure 403 at a second depth B, deeper than A. Figure 3B Different scenarios are shown, where beams of light with different wavelengths interact differently with the bulk material of the sample. A short-wavelength beam 410 interacts primarily by modifying the electrical properties of the material in structure 404, while a second beam 420 with a longer wavelength interacts by heating the material. Using laser beams with different wavelengths provides the ability to deliver more laser / light energy into the material, which makes the electrical / thermal properties of the charge controller more effective.

[0039] Any of a variety of arrangements can be used to project multiple beams of different wavelengths onto the center of the electron beam on the sample. Figure 4 As shown, the light beams can be directed to converge at the center of the electron beam from different ports or directions. The first laser 450 is directed from a first direction to the center C of the electron beam from the electron beam source 440 on the substrate 1, the second laser 460 is directed from a second direction to the center C of the electron beam on the substrate 1, and the third laser 470 is directed from a third direction to the center C of the electron beam on the substrate 1. It will be apparent to those skilled in the art that any number of separate lasers can be used. As long as there is another laser generating light of a different wavelength, the two lasers can share the same wavelength.

[0040] Figure 5An arrangement is shown in which dichroic mirrors are used to project multiple beams of light having different wavelengths along a common optical path. Thus, light from a first laser 500 strikes dichroic mirror 510 and passes through it, while light from a second laser 520 strikes dichroic mirror 510 and is reflected by dichroic mirror 510 to propagate along the same beam path as the radiation from the first laser 500. Additional combinations of lasers and dichroic mirrors can be added. In the example shown, a third laser 530 and a second dichroic mirror 540 are present. Point 550 indicates that any number of such arrangements can be used. It will be apparent to one of ordinary skill in the art that any number of individual lasers can be used. As long as there is another laser generating light of a different wavelength, the two lasers can share the same wavelength.

[0041] Figure 6 The arrangement of trichroic prisms is shown for projecting multiple light beams having different wavelengths along a common optical path. Thus, light from a first laser 600 strikes trichroic prism 610 and passes through it, while light from a second laser 620 strikes trichroic prism 610 and is reflected by trichroic prism 610 to propagate along the same beam path as the radiation from the first laser. Light from a third laser 630 also strikes trichroic prism 610 and is reflected to propagate along the common beam path. Other combinations of lasers and trichroic prisms can be added. In the example shown, there is a fourth laser 640, a fifth laser 650, and a second trichroic prism 660. Point 670 indicates that any number of such arrangements can be used. It will be apparent to one skilled in the art that any number of individual lasers can be used. As long as there is another laser generating light of a different wavelength, the two lasers can share the same wavelength.

[0042] Thus, an electron beam inspection system is disclosed that includes a beam emitting source having two or more wavelengths to help control surface charge. Light beams having different wavelengths can be projected into the electron beam system as separate beams. The light beams having different wavelengths can be combined into a single beam using dichroic filters, hot mirrors, cold mirrors, trichroic prisms, or other optical devices that can manipulate light beams having different wavelengths together. The wavelengths of the light beams can be selected so that they operate at different depths in the substrate. The wavelengths of the light beams can be selected so that they have different effects on the same portion of the substrate, for example, one beam primarily changes the electrical properties of the substrate while another beam primarily changes the temperature of the substrate.

[0043] The following terms may be used to further describe the embodiments:

[0044] 1. A device for inspecting a substrate, the device comprising:

[0045] at least one charged particle beam source arranged to project at least one charged particle beam onto a portion of the substrate; and

[0046] Multiple light sources, the multiple light sources at least include:

[0047] a first light source arranged to project a first light beam having a first wavelength onto a portion of the substrate; and

[0048] A second light source is arranged to project a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate.

[0049] 2. The apparatus for inspecting a substrate according to clause 1, wherein the at least one charged particle beam source comprises an electron beam source.

[0050] 3. The apparatus for inspecting a substrate according to clause 1 or clause 2, wherein the first light source comprises a first laser configured to generate the first light beam, and the second light source comprises a second laser configured to generate the second light beam.

[0051] 4. An apparatus for inspecting a substrate according to clause 1, clause 2 or clause 3, wherein the first wavelength is selected to penetrate the portion of the substrate to a first depth, and the second wavelength is selected to penetrate the portion of the substrate to a second depth different from the first depth.

[0052] 5. Apparatus for inspecting a substrate according to any of clauses 1 to 4, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate and the second wavelength is selected to modify an electrical property in the portion of the substrate.

[0053] 6. An apparatus for inspecting a substrate according to claim 4, wherein the first wavelength is selected to do one of the following: generate a thermal effect in a portion of the wafer at a first depth or modify an electrical property in a portion of the wafer at the first depth, and the second wavelength is selected to do one of the following: generate a thermal effect in a portion of the wafer at a second depth or modify an electrical property in a portion of the wafer at the second depth.

[0054] 7. An apparatus for inspecting a substrate according to any one of clauses 1 to 6, further comprising a beam combiner arranged to combine the first beam and the second beam into a single beam.

[0055] 8. Apparatus for inspecting a substrate according to clause 7, wherein the beam combiner comprises a dichroic mirror.

[0056] 9. Apparatus for inspecting a substrate according to clause 7, wherein the beam combiner comprises a trichroic prism.

[0057] 10. A charged particle beam imaging apparatus for imaging a portion of a substrate, the apparatus comprising:

[0058] at least one source of at least one charged particle beam;

[0059] a charged particle optical system arranged to focus the at least one beam onto a portion of the substrate; and

[0060] An electromagnetic radiation optical system is adapted to generate a first light beam having a first wavelength and a second light beam having a second wavelength different from the first wavelength, and to focus the first light beam and the second light beam on a portion of a substrate.

[0061] 11. The charged particle beam imaging apparatus according to clause 10, wherein the source of the charged particle beam comprises an electron beam source.

[0062] 12. The charged particle beam imaging apparatus according to clause 10 or clause 11, wherein the electromagnetic radiation optical system comprises a first laser configured to generate the first light beam and a second laser configured to generate the second light beam.

[0063] 13. A charged particle beam imaging apparatus according to clause 10, clause 11 or clause 12, wherein the first wavelength is selected to penetrate the portion of the substrate to a first depth, and the second wavelength is selected to penetrate the portion of the substrate to a second depth different from the first depth.

[0064] 14. A charged particle beam imaging apparatus according to any one of clauses 10 to 13, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate and the second wavelength is selected to modify an electrical property in the portion of the substrate.

[0065] 15. A charged particle beam imaging apparatus according to clause 10, wherein the first wavelength is selected to generate a thermal effect in a portion of the substrate at a first depth, and the second wavelength is selected to modify electrical properties in a portion of the substrate at a second depth different from the first depth.

[0066] 16. The charged particle beam imaging apparatus according to any one of clauses 10 to 15, further comprising a beam combiner arranged to combine the first beam and the second beam into a single beam.

[0067] 17. A charged particle beam imaging apparatus according to clause 16, wherein the beam combiner comprises a dichroic mirror.

[0068] 18. A charged particle beam imaging apparatus according to clause 16, wherein the beam combiner comprises a trichroic prism.

[0069] 19. A method for inspecting a substrate, the method comprising the following steps:

[0070] projecting at least one charged particle beam onto a portion of a substrate;

[0071] projecting a first light beam having a first wavelength onto a portion of the substrate; and

[0072] A second light beam having a second wavelength different from the first wavelength is projected onto the portion of the substrate.

[0073] 20. A method of inspecting a substrate according to clause 19, wherein the step of projecting a charged particle beam onto the portion of the substrate is performed using an electron beam source.

[0074] 21. A method for inspecting a substrate according to clause 19 or clause 20, wherein the step of projecting a first light beam having a first wavelength onto a portion of the substrate and the step of projecting a second light beam having a second wavelength different from the first wavelength onto a portion of the substrate are performed simultaneously.

[0075] 22. A method of inspecting a substrate according to clause 19, clause 20 or clause 21, wherein the step of projecting a first light beam having a first wavelength onto a portion of the substrate is performed using a first laser, and the step of projecting a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate is performed using a second laser.

[0076] 23. A method of inspecting a substrate according to any one of clauses 19 to 22, wherein the first wavelength is selected to penetrate the portion of the substrate to a first depth, and the second wavelength is selected to penetrate the portion of the substrate to a second depth different from the first depth.

[0077] 24. A method of inspecting a substrate according to any of clauses 19 to 23, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate and the second wavelength is selected to modify an electrical property in the portion of the substrate.

[0078] 25. A method of inspecting a substrate according to any one of clauses 19 to 22, wherein the first wavelength is selected to generate a thermal effect in a portion of the wafer at a first depth, and the second wavelength is selected to modify electrical properties in a portion of the wafer at a second depth different from the first depth.

[0079] 26. A method of inspecting a substrate according to any one of clauses 19 to 25, further comprising the step of combining the first light beam and the second light beam into a single light beam.

[0080] 27. The method of inspecting a substrate according to clause 26, wherein the combining step is performed using at least one dichroic mirror.

[0081] 28. The method of inspecting a substrate according to clause 26, wherein the combining step is performed using at least one trichroic prism.

[0082] Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it will be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like. It will be understood by those skilled in the art that any use of the terms "wafer" or "die" herein in the context of such alternative applications may be considered synonymous with the more general terms "substrate" or "target portion," respectively. The substrate referred to herein may be processed before or after exposure in, for example, a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. In addition, a substrate may be processed more than once, for example to produce a multi-layer IC, so the term substrate as used herein may also refer to a substrate that already contains multiple processed layers.

[0083] The present invention has been described above with reference to functional building blocks that illustrate the implementation of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined herein. Alternative boundaries may be defined so long as the specified functions and their relationships are appropriately performed.

[0084] The above description of specific embodiments will reveal the general nature of the invention so fully that others can easily modify and / or adapt various applications, such as the specific embodiments, by applying knowledge within the art without undue experimentation and without departing from the general concepts of the invention. Therefore, based on the teachings and guidance presented herein, such modifications and modifications are intended to fall within the meaning and range of equivalents of the disclosed embodiments. It should be understood that the phraseology or terminology herein is for the purpose of description and not limitation, so that the terms or phrases of this specification will be interpreted by those skilled in the art in accordance with the teachings and guidance.

[0085] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. An apparatus for inspecting a substrate, the apparatus comprising: at least one charged particle beam source arranged to project at least one charged particle beam onto a portion of the substrate; as well as A plurality of light sources, the plurality of light sources comprising at least: a first light source arranged to project a first light beam having a first wavelength onto the portion of the substrate; as well as a second light source arranged to project a second light beam having a second wavelength onto the portion of the substrate, the second wavelength being different from the first wavelength, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate to heat a material of the portion of the substrate, and the second wavelength is selected to modify an electrical property in the portion of the substrate, and The portion of the substrate includes a circuit structure and a defect located on the substrate. 2 . The apparatus for inspecting a substrate according to claim 1 , wherein the at least one charged particle beam source comprises an electron beam source. 3 . The apparatus for inspecting a substrate according to claim 1 , wherein the first light source comprises a first laser configured to generate the first light beam, and the second light source comprises a second laser configured to generate the second light beam.

4. The apparatus for inspecting a substrate according to claim 1, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate at a first depth, and the second wavelength is selected to modify electrical properties in the portion of the substrate at a second depth. 5 . The apparatus for inspecting a substrate according to claim 1 , further comprising a beam combiner arranged to combine the first light beam and the second light beam into a single light beam.

6. The apparatus for inspecting a substrate according to claim 5, wherein the beam combiner comprises a dichroic mirror.

7. The apparatus for inspecting a substrate according to claim 5, wherein the beam combiner comprises a trichroic prism.

8. A method for inspecting a substrate, the method comprising the steps of: projecting at least one charged particle beam onto a portion of the substrate; projecting a first light beam having a first wavelength onto the portion of the substrate; as well as projecting a second light beam having a second wavelength onto the portion of the substrate, the second wavelength being different from the first wavelength, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate to heat a material of the portion of the substrate, and the second wavelength is selected to modify an electrical property in the portion of the substrate, and The portion of the substrate includes a circuit structure and a defect located on the substrate.

9. The method for inspecting a substrate according to claim 8, wherein the step of projecting a first light beam having a first wavelength onto the portion of the substrate and the step of projecting a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate are performed simultaneously.

10. The method of inspecting a substrate according to claim 8, wherein the step of projecting a first light beam having a first wavelength onto the portion of the substrate is performed using a first laser, and the step of projecting a second light beam having a second wavelength different from the first wavelength onto the portion of the substrate is performed using a second laser.

11. The method of inspecting a substrate according to claim 8, wherein the first wavelength is selected to generate a thermal effect in the portion of the substrate at a first depth, and the second wavelength is selected to modify electrical properties in the portion of the substrate at a second depth, the second depth being different from the first depth.

Images