Patent ID: 12217927

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the invention. Instead, they are merely examples of apparatuses and methods consistent with aspects related to the invention as recited in the appended claims.

Electronic devices are constructed of circuits formed on a piece of silicon called a substrate. Many circuits may be formed together on the same piece of silicon and are called integrated circuits or ICs. The size of these circuits has decreased dramatically so that many more of them can fit on the substrate. For example, an IC chip in a smart phone can be as small as a thumbnail and yet may include over 2 billion transistors, the size of each transistor being less than 1/1000th the size of a human hair.

Making these extremely small ICs is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. Errors in even one step have the potential to result in defects in the finished IC rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects to maximize the number of functional ICs made in the process, that is, to improve the overall yield of the process.

Defects may be generated during various stages of semiconductor processing. For the reason stated above, it is important to find defects accurately and efficiently as early as possible. A charged particle (e.g., electron) beam microscope, such as a scanning electron microscope (SEM), is a useful tool for inspecting semiconductor wafer surfaces to detect defects. During operation, the charged particle beam microscope scans a primary charged-particle beam, such as an electron beam (e-beam), over a semiconductor wafer held on a wafer holder, and generates an image of the wafer surface by detecting a secondary charged-particle beam reflected from the wafer surface. When the charged-particle beam scans the wafer, charges may be accumulated on the wafer due to large beam current, which may affect the quality of the image. To regulate the accumulated charges on the wafer, an Advanced Charge Controller (ACC) module is employed to illuminate a light beam, such as a laser beam, on the wafer, so as to control the accumulated charges due to effects such as photoconductivity, photoelectric, or thermal effects. It is thus important to improve the performance of the ACC module so as to effectively control the accumulated charges.

ACC modules, however, suffer from the constraints of the SEM. For example, the beam from the ACC module is usually projected onto the wafer at a small angle due to the small working distance and limited space between the electron beam (e-beam) column components and the wafer holder that holds the semiconductor wafer. Because of the small angle, the substantially circular cross-section of the beam from the ACC module is projected onto the wafer with a substantially oval-shaped cross-section and due to the limited space between the e-beam column components and the wafer holder, the amount of the beam landing on the targeted pixel of the wafer is reduced. This reduced amount of the beam landing on the wafer results in reduced efficiency of the ACC module. Because of the small angle, the shape of the beam emitted from the ACC module may be manipulated to fit in the small space between the e-beam column components and the wafer holder (e.g., the space between components132and wafer150ofFIG.2B).

Due to the limited spacing, conventional ACC modules suffer from several trade-offs. For example, conventional ACC modules can use a lens with a small working distance (e.g. distance between beam source450and lens410illustrated inFIG.4A), which can enable more luminous energy to project onto a wafer but with a higher magnification. While the higher magnification can lead to a larger beam size on the wafer, it can also lead to less charge density on the wafer. As another example, conventional ACC modules can use a lens with a larger working distance (e.g. distance between beam source450and lens410illustrated inFIG.4B), but this design has its own issues. While a lower magnification can be achieved resulting in a higher charge density on the wafer, less luminous energy reaches the wafer as part of the beam is blocked by the SEM components (see, e.g.,FIG.4Bwhere430and440block part of the beam).

The disclosed embodiments provide an ACC module that includes a lens system that addresses some or all of these disadvantages. The disclosed embodiments provide an ACC module having a lens system that not only shapes the beam to avoid the SEM components, but also provides, on the wafer, an illuminated area having sufficient charge density.

In some instances, the disclosed system can emit multiple beams from the ACC module at an angle without using any lenses to project a beam with the desired beam spot shape and luminous energy onto the wafer. In other instances, the lens system can include one lens or more than two lenses.

FIG.1illustrates an exemplary electron beam inspection (EBI) system100consistent with embodiments of the present disclosure. While this and other examples refer to an electron beam system, it is appreciated that the techniques disclosed herein are applicable to systems other than electron beam systems, such as an ellipsometer, a velocimeter, a CO2 laser (e.g., for machining), non-electron beam systems where a beam projection spot may be optimized but the space is limited, among others. As shown inFIG.1, EBI system100includes a main chamber101, a load/lock chamber102, an electron beam tool104, and an equipment front end module (EFEM)106. Electron beam tool104is located within main chamber101. EFEM106includes a first loading port106aand a second loading port106b. EFEM106may include additional loading port(s). First loading port106aand second loading port106breceive wafer front opening unified pods (FOUPs) that contain wafers (e.g., semiconductor wafers or wafers made of other material(s)) or samples to be inspected (wafers and samples may be collectively referred to as “wafers” herein).

One or more robotic arms (not shown) in EFEM106may transport the wafers to load/lock chamber102. Load/lock chamber102is connected to a load/lock vacuum pump system (not shown) which removes gas molecules in load/lock chamber102to reach a first pressure below the atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) may transport the wafer from load/lock chamber102to main chamber101. Main chamber101is connected to a main chamber vacuum pump system (not shown) which removes gas molecules in main chamber101to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subject to inspection by electron beam tool104. Electron beam tool104may be a single-beam system or a multi-beam system. A controller109is electronically connected to electron beam tool104. Controller109may be a computer configured to execute various controls of EBI system100. While controller109is shown inFIG.1as being outside of the structure that includes main chamber101, load/lock chamber102, and EFEM106, it is appreciated that controller109can part of the structure.

FIG.2Aillustrates a charged particle beam apparatus in which an electron beam system may comprise a single primary beam that may be configured to generate a secondary beam. A detector may be placed along an optical axis105, as shown inFIG.2A. In some embodiments, a detector may be arranged off axis.

As shown inFIG.2A, an electron beam tool104may include a wafer holder136supported by motorized stage134to hold a wafer150to be inspected. Electron beam tool104includes an electron beam source, which may comprise a cathode103, an anode120, and a gun aperture122. Electron beam tool104further includes a beam limit aperture125, a condenser lens126, a column aperture135, an objective lens assembly132, and an electron detector144. Objective lens assembly132, in some embodiments, may be a modified swing objective retarding immersion lens (SORIL), which includes a pole piece132a, a control electrode132b, a deflector132c, and an exciting coil132d. In an imaging process, an electron beam161emanating from the tip of cathode103may be accelerated by anode120voltage, pass through gun aperture122, beam limit aperture125, condenser lens126, and focused into a probe spot by the modified SORIL lens and then impinge onto the surface of wafer150. The probe spot may be scanned across the surface of wafer150by a deflector, such as deflector132cor other deflectors in the SORIL lens. Secondary electrons emanated from the wafer surface may be collected by detector144to form an image of an area of interest on wafer150.

There may also be provided an image processing system199that includes an image acquirer200, a storage130, and controller109. Image acquirer200may comprise one or more processors. For example, image acquirer200may comprise a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, and the like, or a combination thereof. Image acquirer200may connect with detector144of electron beam tool104through a medium such as an electrical conductor, optical fiber cable, portable storage media, IR, Bluetooth, internet, wireless network, wireless radio, or a combination thereof. Image acquirer200may receive a signal from detector144and may construct an image. Image acquirer200may thus acquire images of wafer150. Image acquirer200may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, and the like. Image acquirer200may be configured to perform adjustments of brightness and contrast, etc. of acquired images. Storage130may be a storage medium such as a hard disk, random access memory (RAM), cloud storage, other types of computer readable memory, and the like. Storage130may be coupled with image acquirer200and may be used for saving scanned raw image data as original images, and post-processed images. Image acquirer200and storage130may be connected to controller109. In some embodiments, image acquirer200, storage130, and controller109may be integrated together as one control unit.

In some embodiments, image acquirer200may acquire one or more images of a sample based on an imaging signal received from detector144. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image comprising a plurality of imaging areas that may contain various features of wafer150. The single image may be stored in storage130. Imaging may be performed on the basis of imaging frames.

The condenser and illumination optics of the electron beam tool may comprise or be supplemented by electromagnetic quadrupole electron lenses. For example, as shown inFIG.2A, the electron beam tool104may comprise a first quadrupole lens148and a second quadrupole lens158. In some embodiments, the quadrupole lenses are used for controlling the electron beam. For example, first quadrupole lens148can be controlled to adjust the beam current and second quadrupole lens158can be controlled to adjust the beam spot size and beam shape.

AlthoughFIG.2Ashows electron beam tool104as a single-beam inspection tool that may use only one primary electron beam to scan one location of wafer150at a time, embodiments of the present disclosure are not so limited. For example, electron beam tool104may also be a multi-beam inspection tool that employs multiple primary electron beamlets to simultaneously scan multiple locations on wafer150.

FIG.2Billustrates a charged particle beam apparatus with an ACC module108for directing an illumination beam to a spot on a wafer during inspection consistent with embodiments of the present disclosure. The components ofFIG.2Bare similar to those ofFIG.2A, except thatFIG.2Bprovides ACC module108.

As stated above, ACC module108projects a beam onto wafer150for controlling a charge on the wafer surface of the charged particle beam tool. Due to the limited space beneath charged particle beam tool104, however, ACC module108may project a beam at an angle θ of less than 45°, but usually less than 30° in order to project the beam through the small space between the objective lens assembly132of electron beam tool104and wafer150. In some embodiments, electron beam tool104can generate multiple primary electron beamlets to simultaneously scan multiple locations on wafer150. In some embodiments, the beam projected by ACC module108can charge a location on wafer150large enough so that multiple primary electron beamlets can scan corresponding portions on wafer150. In some embodiments, electron beam tool104can include a plurality of ACC modules108to project a beam onto wafer150for each primary electron beamlet, a plurality of the primary electron beamlets, or any combination thereof.

FIG.3Ais a side view of an electron beam system300consistent with embodiments of the present disclosure. As shown inFIG.3A, electron beam system300includes an electron beam tool310, an ACC module320, and a wafer holder330on which a sample to be inspected (e.g., a wafer340) is disposed. Electron beam tool310may emit a primary electron beam312onto an area of interest on wafer340, and collect secondary electrons emanated from the wafer surface to form an image of the area of interest on wafer340. ACC module320, positioned at a small angle θ, may include an ACC beam source that emits a light beam322(e.g., laser beam) onto wafer340and form a beam spot of light beam322on the wafer surface. When primary electron beam312irradiates the area of interest on wafer340, charges may be accumulated due to a large electron beam current. Light beam322emitted from ACC module320may be configured to regulate the accumulated charges due to photoconductivity or photoelectric effect, or a combination of photoconductivity and photoelectric effect, among others. ACC module320may be positioned at angle θ, usually less than 30°, in order to project light beam322onto wafer340without landing on the column components of electron beam tool310.

FIG.3Bis a top view of electron beam system300during operation of wafer inspection, consistent with embodiments of the present disclosure. To simplify the illustration, electron beam tool310is omitted fromFIG.3B. As shown inFIG.3B, in electron beam system300, light beam322from ACC module320may be aligned with the field of view (FOV) of electron beam tool310. In some embodiments, a special designed sample surface may be used to collect the light beam signal emitted from ACC module320. In yet other embodiments, the wafer surface or a smooth surface may also be used to collect the light beam signal emitted from ACC module320.

In some embodiments, such as the embodiment illustrated inFIG.3A, ACC module320is disposed outside of a vacuum chamber, in which electron beam tool310and wafer340are disposed. During operation of the electron beam system300, light beam322may pass through one or more windows formed in the vacuum chamber. In some alternative embodiments, ACC module320may be disposed inside of the vacuum chamber.

FIGS.3C-3Eshow various views of the beam emitted from ACC module320, consistent with some embodiments of the present disclosure. For example,FIG.3Cis a top/side view,FIG.3Dis a view in the Y-X plane relative to ACC module320, andFIG.3Eis a top view of the beam emitted from an ACC module and projected onto wafer. To improve performance of ACC module320given the small working distance and limited space between e-beam column components310and wafer holder330, ACC module320provides a high power density beam322on the wafer340, the area of the beam projected onto the semiconductor wafer (hereinafter “illuminated area”)322bmay be larger than the field of view (FOV) or pixel of the e-beam system with the power distribution of the beam being uniform in the FOV or pixel. That is, illuminated area322bcan have a substantially round shape with a size that is slightly larger than the size of the FOV or pixel of the e-beam system. The shape of illuminated area322bmay be substantially circular when emitted beam322ais ellipse-shaped to cause circular illumination, or may be ellipse-shaped when emitted beam322ais circular-shaped.

Typically, beam322from ACC module320is projected onto wafer340at an angle θ of less than 30° due to the small working distance and limited space between e-beam column components310and wafer holder330. Because of the small angle θ, the shape of the beam emitted from the ACC module (hereinafter “emitted beam”)322ais different from the shape of illuminated area322b. Emitted beam322amay be ellipse-shaped, as illustrated inFIG.3C, and illuminated area322bmay be round-shaped on the semiconductor wafer340, as illustrated inFIG.3E, due to small angle θ. Additionally, because the space between the e-beam column components and the wafer holder is limited in the direction perpendicular to the surface of the wafer holder, the space may limit the angle of a light cone that can pass through the space, such as to a light cone angle of less than 20°.

FIG.4AandFIG.4Bare views in the tangential (Y-Z) plane of conventional configurations of an ACC module460. In order to provide a high density beam on the wafer, the beam source450may have high luminous exitance and most of the light can be collected and projected onto the wafer with a small projection size. Providing more luminous energy to the wafer may be facilitated by using a lens with high magnification so that the emitted beam has a light cone angle small enough to pass through the limited space between the e-beam column components and the wafer holder. For example, with respect toFIG.4A, in order to provide more luminous energy to the wafer, high magnification of lens410may be facilitated by positioning lens410closer to the beam source450. High magnification of lens410may be desired to project a beam420with a light cone angle φ sufficiently small enough to pass through the space between the e-beam column components430and the wafer holder440. However, the high magnification results in a larger beam size. Projecting a beam size that is too large is undesirable since illuminated area size is inversely related to luminance. Thus, an illuminated area size that is too large results in a reduced amount of luminous energy provided to the wafer. A reduction of luminous energy provided on the wafer can be problematic in terms of achieving higher throughput, as higher amounts of luminous energy provided to the wafer increase power density and, thus, achieve higher processing speeds during operation of wafer inspection.

In conventional systems, reducing the beam size requires lower magnification. In the configuration ofFIG.4B, low magnification of lens410is achieved by positioning lens410closer to beam source450. Low magnification of lens410can provide a beam420with a smaller beam size. However, low magnification of lens410provides a beam with a larger light cone angle φ. Because of the larger light cone angle φ, some of beam420is blocked by the e-beam column components430and wafer holder440. This configuration also results in a reduced amount of luminous energy provided to the wafer since at least some of beam420does not reach the wafer.

Due to the small working distance and limited space between the e-beam column components and the wafer holder that holds the wafer, some conventional ACC modules may not have a lens system that can project a beam with a sufficiently small illuminated area size or sufficiently high luminous energy onto the wafer. In order to solve this problem, the disclosed systems can configure the lens system of the ACC module to shape the illuminated area by manipulating a fan angle of the beam in a tangential plane and a fan angle of the beam in a sagittal plane. This method of shaping the projection spot of the beam on the wafer is one method of facilitating the desired cross-section shape of the illumination area on the wafer. A person of ordinary skill in the art would recognize that additional methods of facilitating the desired cross-section shape of the illumination area on the wafer exist.

FIG.5Ais a view in the tangential (Y-Z) plane of an exemplary ACC module configuration consistent with embodiments of the present disclosure. The ACC module560may be part of an EBI system, such as EBI100illustrated inFIG.1and the EBI system illustrated inFIG.2C. In the tangential (Y-Z) plane as shown inFIG.5A, the emitted beam is provided by the beam source550and collected by a first lens510at a small distance due to its large divergence angle α1. The fan angle γ1of beam520is manipulated by first lens510in order to project beam520through the limited space between the e-beam column components530and the wafer holder540. First lens510may be a cylindrical lens configured to manipulate beam520such that beam520has a light cone angle β sufficiently small enough to completely pass through the space between e-beam column components530and wafer holder540. As a result, a large magnification can be obtained and, therefore, beam520with sufficiently small light cone angle β can pass through the space between e-beam column components530and wafer holder540.

FIG.5Bis a view in the sagittal (X-Z) plane of the exemplary ACC module configuration illustrated inFIG.5A. As shown inFIG.5B, the emitted beam is collected by a second lens512at a large distance due to its small divergence angle α2, where α2is less than α1. Second lens512manipulates the fan angle γ2of beam520in order to project beam520with a sufficiently small beam size. Second lens512may also be a cylindrical lens. While a spherical lens may be used in some embodiments, it may not be used in others because its rotational symmetry causes the cross-section of beam520to maintain the same elliptical shape after passing through the lens, which disadvantageously may not allow beam520to pass through the space between e-beam column components530and wafer holder540. In some embodiments, a combination of rotationally asymmetric lenses (e.g., cylindrical lenses) may be used because the rotational asymmetry of each lens advantageously allows the cross-section of beam520to be manipulated in separate planes. The combination of first lens510and second lens512results in providing a beam with higher luminous energy to the wafer such that a higher power density is provided to the wafer and thus, higher processing speeds are achieved during operation of wafer inspection. As a result, a lower magnification can be obtained and, therefore, a beam with a sufficiently high beam density and luminous energy can reach the wafer. Therefore, ACC module560can project a beam that bypasses e-beam column components530and wafer holder540without impact and appropriately charges the wafer with the desired luminous energy.

ACC module560is not limited to a single configuration. That is, the number of lenses used and the positioning of those lenses within ACC module560can vary. Additionally, first lens510and second lens512are not limited to cylindrical lens and can comprise lenses of various shapes and dimensions, including different curvatures. For example, in one configuration of the ACC module, the distance between beam source550and first lens510may be 6.775 mm, the thickness of first lens510may be 2.500 mm, the distance between first lens510and second lens512may be 11.90 mm, the thickness of second lens512may be 4.000 mm, and the distance between second lens512and e-beam column components530may be 109.8 mm.

FIG.6A,FIG.6B, andFIG.6Care views of a cross-section of a beam emitted from the beam source of and within an ACC module consistent with embodiments of the present disclosure (e.g., ACC module inFIG.2B,FIG.3A, andFIGS.5A-5B).FIG.6Aillustrates a cross-section of the emitted beam after it leaves beam source550of ACC module560shown inFIGS.5A-5B(e.g., emitted beam322ainFIG.3C,FIG.3D, andFIG.3E) whileFIG.6Billustrates a cross-section of the same emitted beam after it leaves second lens512of ACC module560shown inFIGS.5A-5B. As shown inFIG.6AandFIG.6B, the cross-section of the emitted beam is ellipse-shaped before and after it passes through the lens system.FIG.6Cillustrates a cross-section of the same beam as it is projected on the wafer within the space between e-beam column components530and wafer holder540ofFIGS.5A-5B(e.g., illuminated area322binFIG.3C,FIG.3D, andFIG.3E). The dimensions of the cross sections of the beam may vary with the different configurations within the ACC module. For example, in one ACC module consistent with embodiments of the present disclosure, the length L of the emitted beam inFIG.6Amay be 8 micrometers while the width W of the same emitted beam may be 2 micrometers. In the same configuration, the length L of the same beam inFIG.6Bafter passing the lens system may be 56 micrometers while the width may be 25 micrometers. In the same configuration, the length L of the same beam inFIG.6Cprojected onto the wafer may be 56 micrometers while the width W may be 50 micrometers. However, the illuminated area inFIG.6Cmay have a diameter of approximately 50 to 300 micrometers.

FIG.7is an exemplary flowchart of a process700for manipulating a beam in an electron beam system by using a lens system, consistent with embodiments of the present disclosure. Process700may be performed by an ACC module, such as ACC module108in illustrated inFIG.2B. As shown inFIG.7, at step710, the ACC module comprising a beam source (e.g., beam source550ofFIGS.5A-5B) may emit a beam having an ellipse shape (e.g., emitted beam322ainFIG.3CandFIG.3E;FIG.6A). The beam is emitted having a first divergence angle in the tangential plane (e.g., α1inFIG.5A) and a second divergence angle in the sagittal plane (e.g., α2inFIG.5B). At step720, the emitted beam passes through the lens system, where the cross-section of the emitted beam is shaped into a different ellipse shape (e.g., ellipse shape ofFIG.6B) by the lens system (e.g., first lens510and second lens512inFIG.5AandFIG.5B). For example, the emitted beam is collected by a first lens, which manipulates the fan angle in the tangential plane of the beam leaving the first lens so that the light cone angle of the emitted beam is small enough to pass completely through the space between the e-column components and the wafer holder. The emitted beam may then be collected by a second lens, which manipulates the fan angle in the sagittal plane of the beam leaving the second lens so that the size of the illuminated area size is sufficiently small enough to provide higher luminous energy to the wafer.

At step730, the ACC module projects the beam onto the wafer so that the illuminated area is substantially round. The substantially round shape of the illuminated area increases the area of the wafer that is irradiated by the beam, which consequently increases the area of the wafer that is provided with higher luminous energy and appropriately charged.

Although the cross-section shape of the emitted beam described is an ellipse, the cross-section shape of the emitted beam may be any shape that facilitates the desired cross-section shape of the illuminated area on the wafer.

The embodiments may further be described using the following clauses:1. An electron beam system, the system comprising:

an electron beam tool; and

an advanced charge controller (ACC) module comprising:a laser source configured to emit a beam, anda lens system configured to shape the emitted beam by manipulating a fan angle of the emitted beam in a tangential plane and a fan angle of the beam in a sagittal plane for illuminating an area on a wafer beneath the electron beam tool.2. The system of clause 1, wherein the beam may comprise a plurality of beams.3. The system of clause 1, wherein the lens system is positioned at an angle of 30 degrees or less with respect to the wafer.4. The system of clause 1, wherein the lens system is configured to project the beam such that a light cone angle of the beam is less than 20 degrees.5. The system of clause 1, wherein the lens system comprises a first lens and a second lens.6. The system of clause 5, wherein the first lens is configured to manipulate the fan angle of the emitted beam in the tangential plane and the second lens is configured to manipulate the fan angle of the emitted beam in the sagittal plane.7. The system of clause 6, wherein a distance between the first lens and the laser source is shorter than a distance between the second lens and the laser source.8. The system of clause 7, wherein at least one of the first lens or the second lens has a cylindrical shape.9. The system of clause 1, wherein the illuminated area of the wafer is substantially circular when viewed from above the wafer.10. The system of clause 1, wherein a divergence angle in the tangential plane is equal to or different from a divergence angle in the sagittal plane.11. A method for manipulating a beam in an electron beam system, the method comprising:

emitting a beam from a laser source of an advanced charge controller (ACC) module; and

shaping, using a lens system, the emitted beam by manipulating a fan angle of the emitted beam in a tangential plane independently from manipulating a fan angle of the emitted beam in a sagittal plane for illuminating an area on a wafer.12. The method of clause 11, wherein the beam may comprise a plurality of beams.13. The method of clause 11, further comprising projecting the beam such that a light cone angle of the beam is less than 20 degrees.14. The method of clause 11, wherein the lens system comprises a first lens and a second lens.15. The method of clause 14 further comprising the first lens manipulating the fan angle of the emitted beam in the tangential plane and the second lens manipulating the fan angle of the emitted beam in the sagittal plane.16. The method of clause 15, wherein a distance between the first lens and the laser source is shorter than a distance between the second lens and the laser source.17. The method of clause 16, wherein at least one of the first lens or the second lens each has a cylindrical shape.18. The method of clause 11, wherein the illuminated area of the wafer is substantially circular when viewed from above the wafer.19. The method of clause 11, wherein a divergence angle in the tangential plane is equal to or different from a divergence angle in the sagittal plane.20. An advanced charge controller (ACC) module comprising:

a laser source configured to emit a beam for illuminating an area on a wafer; and

a lens system configured to shape the emitted beam to have a substantially elliptical cross-section to cause the area of the wafer illuminated by the emitted beam to have a substantially circular cross-section.21. The ACC module of clause 20, wherein the beam comprises a plurality of beams.22. The ACC module of clause 20, wherein the lens system is positioned at an angle of 30 degrees or less with respect to a surface of the wafer.23. The ACC module of clause 20, wherein the lens system is configured to project the beam such that a light cone angle of the beam is less than 20 degrees.24. The ACC module of clause 20, wherein the lens system comprises a first lens and a second lens.25. The ACC module of clause 24, wherein the first lens is configured to manipulate a fan angle of the emitted beam in a tangential plane and the second lens is configured to manipulate a fan angle of the emitted beam in a sagittal plane.26. The ACC module of clause 25, wherein a distance between the first lens and the laser source is shorter than a distance between the second lens and the laser source.27. The ACC module of clause 26, wherein at least one of the first lens or the second lens has a cylindrical shape.28. The ACC module of clause 25, wherein a divergence angle in the tangential plane is equal to or different from a divergence angle in the sagittal plane.29. A method comprising:emitting a laser beam with a cross-section comprising curved sides at an angle less than a predetermined angle with reference to a surface of a wafer;modifying, using a lens system, the laser beam such that the cross-section of the laser beam is a different shape with curved sides; andilluminating the surface of the wafer with the modified laser beam to form an exposed area that has a substantially circular cross-section.30. An advanced charge controller (ACC) module comprising:

a laser source configured to emit a beam for illuminating an area on a wafer; and

a lens system configured to shape the emitted beam to cause the area of the wafer illuminated by the emitted beam to have a substantially circular cross-section, wherein the lens system is positioned at an angle less than 45 degrees with respect to the wafer.31. The ACC module of clause 30, wherein the lens system is configured to shape the emitted beam to have a substantially elliptical cross-section.32. The ACC module of clause 30, wherein the lens system is positioned at an angle of 30 degrees or less with respect to the wafer.33. The ACC module of clause 30, wherein the lens system is configured to project the beam such that a light cone angle of the beam is less than 20 degrees.

A non-transitory computer readable medium may be provided that stores instructions for a processor of a controller (e.g., controller109ofFIG.1) for controlling the ACC module, consistent with embodiments in the present disclosure, based on the beam profile and beam power of the light beam. For example, based on the beam power of light beam, the controller may automatically adjust a working current of the ACC beam source included in the ACC module to keep an output power of the ACC beam source at a target power or to remain stable. Moreover, based on the beam power of the light beam, the controller may be configured to monitor a location of the beam spot formed by the light beam on the wafer surface. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a Compact Disc Read Only Memory (CD-ROM), any other optical data storage medium, any physical medium with patterns of holes, a Random Access Memory (RAM), a Programmable Read Only Memory (PROM), and Erasable Programmable Read Only Memory (EPROM), a FLASH-EPROM or any other flash memory, Non-Volatile Random Access Memory (NVRAM), a cache, a register, any other memory chip or cartridge, and networked versions of the same.

As used herein, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, if it is stated that a component may include A or B, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component may include A, B, or C, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

It will be appreciated that the embodiments of the present disclosure are not limited to the exact construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The present disclosure has been described in connection with various embodiments, other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.