System and method for analyzing wafer characteristics before injection at the site

Abstract

The ion implantation system includes a wafer inspection system for inspecting the wafer prior to ion implantation. The inspection facilitates diagnosis by helping to distinguish between the performance of the ion implantation process and the performance of upstream processes affecting the ion implantation process. The inspection may be performed while the wafer is on an aligner, while it is inside a load lock chamber, or while it is being processed in a different manner by a wafer transfer system at an end station. The inspection may be performed without adding delay to the wafer processing. The inspection may include Modulated Optical Reflectance (MOR) spectroscopy, and the inspection may be performed via optical fiber. The optical circuit may include a wavelength coupler so that the pump laser and probe laser of the MOR system can be focused through a single lens to a narrowly determined inspection point.

Description

Technology Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 619,339 filed on January 10, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0002] Ion implantation systems are used in the integrated circuit (IC) device manufacturing industry for damage engineering and to provide a controlled dose of impurities to semiconductor wafers. A mask can be used to form a pattern for implantation. Factors such as the depth and concentration profile of the implantation can be modified by selecting the operating parameters of the ion implantation system. IC device manufacturing involves multiple ion implantations with various patterns, different types of impurities, various concentrations, and various depths. Brief explanation of the drawing

[0003] FIG. 1 shows an end station for an ion implantation system according to some aspects of the present disclosure. FIG. 2 shows an aligner according to some embodiments. FIG. 3 shows a wafer inspection system according to some embodiments. FIG. 4 is another drawing of a wafer inspection system according to some embodiments. FIG. 5 shows an ion implantation system according to some embodiments. FIG. 6 shows an end station for an ion implantation system according to some embodiments. FIG. 7 shows an end station for an ion implantation system according to some embodiments. FIG. 8 shows an end station robot according to some embodiments. FIG. 9 shows an end station for an ion implantation system according to some embodiments. FIGS. 10A-10C shows a workpiece handler according to some embodiments. FIG. 11 provides a flowchart of a method according to some aspects of the present disclosure. Specific details for implementing the invention

[0004] The present disclosure provides a number of different embodiments or examples for implementing various features of the present disclosure. Specific components and arrangements are provided to clarify and illustrate the present disclosure. These specific embodiments should not be construed as limiting the scope of the claims.

[0005] One aspect of the present disclosure relates to an ion implantation system that provides inspection of a wafer prior to performing ion implantation. The success of said ion implantation depends on the state of the wafer prior to said ion implantation process. For example, ion implantation for a shallower depth is typically performed after one or more ion implantations targeting a deeper depth. The correct dose for said ion implantation targeting a shallower depth depends not only on the desired charge carrier concentration at the shallower depth but also on the type and concentration of dopants left by previous ion implantation processes. Deviations in said processes may affect the current process.

[0006] Another condition affecting the current ion implantation process is the crystal structure of the substrate. The depth of ion implantation is strongly influenced by the disorder (amorphization) of the crystal structure. In some cases, the crystal structure is intentionally made partially amorphous to control the implantation depth. In some cases, the crystal structure becomes partially amorphous incidentally or unintentionally. For all these reasons, the inventors have found that wafer inspection performed after ion implantation often fails to provide sufficient evidence to determine whether the current ion implantation process is operating as intended or if adjustments are required. The present disclosure addresses this problem with an ion implantation system having an integrated wafer inspection system capable of providing wafer inspection immediately prior to ion implantation.

[0007] An ion implantation system may include an ion source, a beamline, an end station, and a wafer transport system. The wafer transport system is located within the end station and transports a wafer from a wafer carrier at or near atmospheric pressure to a workpiece handler under vacuum within the process chamber of the end station. The ion source generates an ion beam, the beamline guides the ion beam, and the workpiece handler holds the wafer in the path of the ion beam. The workpiece handler determines an implant plane, which is the plane on which the ion beam is irradiated onto the wafer. In some embodiments, the workpiece handler is configured to move the wafer across the path of the ion beam while holding the wafer on the fixed implant plane.

[0008] In some embodiments, the wafer transfer system comprises a load lock, an aligner, and one or more robots. The aligner rotates the wafer relative to an alignment mark provided on the wafer to set its orientation. The aligner is provided because the depth of ion implantation may vary depending on the angle of incidence of the ion beam relative to the direction of the wafer's crystal structure. The load lock system is used to transition the wafer from atmospheric pressure or near-atmospheric conditions outside the process chamber to vacuum conditions inside the process chamber. A first robot may remove the wafer from the wafer carrier and place it on the aligner. After the wafer is aligned, a second robot may remove the wafer from the aligner and place it in the load lock chamber. After the load lock chamber is evacuated, a third robot may remove the wafer from the load lock chamber and place it on the workpiece handler. The workpiece handler may place the wafer on the implantation plane and scan the wafer along the implantation plane. Alternatively, the aligner may be located within the process chamber.

[0009] In some embodiments, the inspection is performed while the wafer is inside the load lock chamber. The wafer remains inside the load lock chamber while the load lock chamber is being evacuated. This provides an opportunity to inspect the wafer without increasing process time. In some alternative embodiments, the wafer carriers are transported through the load lock chamber instead of individual wafers, and inspection inside the load lock chamber may not be practical.

[0010] In some embodiments, the inspection is performed while the wafer is on the aligner. The wafer may remain in a stationary state for a short time while on the aligner. The scan can be executed during this short time without increasing the wafer processing time. In some embodiments, the wafer is inspected after alignment. Inspection after alignment allows for precise determination of the inspection point on the wafer. In some embodiments, the inspection is performed closer to the periphery of the wafer than to the center of the wafer. Using a point near the periphery as the inspection point makes it easy to maintain the output coupler or other detection head of the wafer inspection system in a fixed position near the wafer surface while the wafer is on the aligner. Placing the detection head near the periphery makes it easy to push the wafer under the detection head when the wafer is loaded onto the aligner. An additional advantage of inspection on the aligner is that the aligner provides a convenient attachment point for the components of the wafer inspection system.

[0011] In some embodiments, the inspection is a pointwise inspection. Pointwise inspection is advantageous over a full wafer scan, including the ability to complete the inspection quickly and the ability to perform the inspection with smaller equipment. In some embodiments, the wafer on the aligner is inspected at multiple inspection points equidistant from the center of the wafer. The ability of the aligner to rotate the wafer provides an opportunity to quickly and precisely reposition the wafer so that inspection can be performed at multiple inspection points using a single fixed detection head.

[0012] In some embodiments, the inspection is performed while the wafer is held by one of the robot arms of the wafer transfer system. The wafer may remain stationary on the robot arm while waiting for a destination, such as the aligner, the load lock chamber, or the workpiece handler, to be emptied. Such a pause provides an opportunity to inspect the wafer without increasing the wafer processing time.

[0013] In some embodiments, the inspection is performed while the wafer is on the workpiece handler. The inspection may be performed while the wafer is in a first direction. The first direction may be convenient for the inspection. The workpiece handler may then reorient the wafer so that its surface is placed on the injection plane.

[0014] In some embodiments, the inspection is performed via an optical fiber. Performing the inspection via an optical fiber provides flexibility in positioning other components of the inspection system. In some embodiments, a component of the inspection system is located outside the process chamber. In some embodiments, the component is a laser. In some embodiments, the component is a photodetector. Placing the components of the inspection system outside the process chamber can extend their lifespan. In some embodiments, a component of the inspection system is mounted on the aligner. Mounting the component on the aligner shortens the path of the optical fiber extending from the component to an output coupler maintained at a fixed position on the aligner.

[0015] In some embodiments, the inspection system is a modulated optical reflectance (MOR) system. The MOR system includes a pump laser, a probe laser, and a photodetector. In some embodiments, the MOR system includes an optical circuit comprising optical fibers and a wavelength coupler. The wavelength coupler facilitates focusing the pump laser and the probe laser to the same inspection point. The wavelength coupler enables the pump laser output, the probe laser output, and the reflected light of the probe laser from the inspection point to all travel through a single optical fiber and a single lens of an output coupler attached to the single optical fiber.

[0016] In some embodiments, an output coupler including a lens at the end of the optical fiber is maintained in a fixed position directly above the inspection point. Maintaining the output coupler in a fixed position eliminates the cause of variation in the inspection data. In some embodiments, the output coupler is movable. For example, a robot may be provided to move the position of the output coupler. The movable output coupler can facilitate inspecting the wafer without interfering with the normal movement of the wafer through the end station. The lens can focus the pump laser and probe laser outputs to the inspection point and focus the reflected light of the probe laser from the inspection point to the optical fiber. In some embodiments, the pump laser is modulated at a single frequency. Using a single frequency for each inspection (unlike frequency scanning) allows the inspection to be performed quickly and can provide sufficient evidence for the purpose of the wafer inspection system.

[0017] The wafer inspection system provides inspection data that can be used to make a diagnostic decision regarding the wafer. In some embodiments, the wafer is discarded based on the diagnostic decision. In some embodiments, a calibration process is performed on the wafer based on the diagnostic decision. The ion implantation may be deferred until the calibration process is completed. In some embodiments, the ion implantation performed after the inspection is modified based on the diagnostic decision. In some embodiments, the operation of a processing tool upstream of the ion implantation system is modified based on the diagnostic decision.

[0018] In some embodiments, making a diagnostic decision from the inspection data includes comparing the inspection data with previously acquired inspection data. In some embodiments, the previously acquired inspection data is obtained by the inspection system by inspecting one or more previously processed wafers. In some embodiments, a second inspection of the wafer is performed after the ion implantation, and the diagnostic decision is made by comparing the result of the second inspection with the result of the first inspection.

[0019] FIG. 1 illustrates an end station (100) for an ion implantation system according to some embodiments of the present disclosure. The end station (100) includes a process chamber (13) and a front end module (29). The process chamber (13) is under vacuum and is where the wafer (122) is implanted. The front end module (29) is maintained at or near atmospheric pressure. An aligner (25), a first robot (27A), and a second robot (27B) are positioned within the front end module (29). A workpiece handler (175), a third robot (15B), and a fourth robot (15A) are positioned within the process chamber (13).

[0020] The first robot (27A) extends through one of the load ports (31) to remove a wafer (122) from a wafer carrier (35) and place it on the aligner (25). The wafer carrier (35) is a multi-wafer transfer module, such as a wafer pod or wafer cassette. In some embodiments, the wafer carrier (35) is a front opening unified pod (FOUP). An automated overhead transfer or other transfer system may be used to move the wafer carrier (35) between the ion implantation system and other workstations of the integrated circuit (IC) manufacturing plant.

[0021] The aligner (25) rotates the wafer (122) and sets an angular direction based on the alignment mark (26) on the wafer (122). The wafer inspection system (20) inspects the wafer (122) while the wafer is on the aligner (25). The wafer inspection system (20) includes an optical fiber (23), an output coupler (21), and a component (19). The component (19) is mounted on the side of the aligner (25). The output coupler (21) may be maintained in a fixed position to inspect the wafer (122) at an inspection point near the periphery.

[0022] The first load lock chamber (17B) and the second load lock chamber (17A) are located between the front end module (29) and the process chamber (13). The second robot (27B) removes the wafer (122) from the aligner (25) and places it in the first load lock chamber (17B). After the first load lock chamber (17B) is exhausted, the third robot (15B) removes the wafer (122) and places it on the workpiece handler (175).

[0023] Ion implantation is performed while the wafer (122) is held by the workpiece handler (175). The workpiece handler (175) reorients the wafer (122) to align the wafer (122) with the implantation plane. In some embodiments, the workpiece handler (175) sweeps the wafer (122) across the beam path (112a) in a slow scan direction while holding the wafer (122) above the implantation plane. In some embodiments, the workpiece handler (175) is stationary and the beam path (112a) sweeps across the wafer (122) in both a fast scan direction and a slow scan direction.

[0024] After ion implantation, the fourth robot (15A) removes the wafer (122) from the workpiece handler (175) and places it in the second load lock chamber (17A). After the wafer (122) reaches the pressure of the front end module (29), the fourth robot (15A) removes the wafer (122) from the second load lock chamber (17A) and returns it to one of the wafer carriers (35).

[0025] Components of an end station (100) that secures and transports the wafer (122) between the wafer carrier (35) and the workpiece handler (175) constitute a wafer transport system (11). In the wafer transport system (11), the wafer (122) is introduced into the process chamber (13) through the first load lock chamber (17B) and removed from the process chamber (13) through the second load lock chamber (17A), but each of the load lock chambers (17A, 17B) can be used to transport the wafer (122) in and out of the process chamber (13). Additionally, more or fewer load lock chambers (17A, 17B) may be provided.

[0026] The wafer transfer system (11) uses a fourth robot (15A) for transferring processed wafers (122) and a third robot (15B) for transferring unprocessed wafers (122) within the process chamber (13), but it will be understood that the fourth robot (15A) can also transfer unprocessed wafers (122) and the third robot (15B) can also transfer processed wafers (122). Additionally, the wafer transfer system (11) may have more or fewer robots within the process chamber (13).

[0027] The wafer transfer system (11) uses the first robot (27A) to transfer a processed wafer (122) to a wafer carrier (35) and to transfer an unprocessed wafer (122) to an aligner (25). The wafer transfer system (11) uses the second robot (27B) to transfer a wafer from the aligner to the first load lock chamber (17B). These functions may be distributed differently between the first robot (27A) and the second robot (27B), and may be distributed among more or fewer robots within the front end module (29). The number of load ports (31) through which the robots access the wafer carrier (35) may also be configured differently without departing from the spirit and scope of the present disclosure.

[0028] FIG. 2 provides a top view (200) showing an embodiment of an aligner (25) using a more detailed example than provided in FIG. 1. The aligner (25) includes a base (207), a workpiece support (201), a chuck (205), and an alignment mark detection device (209). The workpiece support (201) may have an arc-shaped groove (203) configured to support the perimeter of the wafer (122). The chuck (205) may be rotatably mounted on the base (207) to grip and rotate the wafer (122). The chuck (205) may be, for example, a vacuum chuck or an electrostatic chuck. The alignment mark detection device (209) may be an optical sensor or other type of detection device capable of detecting the alignment mark. The wafer inspection system (20) includes a component (19) mounted on the side of the base (207) and an output coupler (21) maintained over the position occupied by the wafer (122) when fixed by the workpiece support (201).

[0029] FIG. 3 illustrates a MOR system (300) capable of providing a wafer inspection system (20). The MOR system (300) comprises a pump laser (301), a wavelength coupler (305), a probe laser (309), a circulator (313), a photodetector (317), and an output coupler (21). Light (318) from the pump laser (301) is transmitted to the wavelength coupler (305) via an optical fiber (303), and from the wavelength coupler (305) to the output coupler (21) via an optical fiber (23). The output coupler (21) includes a lens that focuses the light (318) onto the wafer (122). The light (318) stimulates a response at an inspection point on the wafer (122). The light (318) may be modulated to facilitate the detection of a time-dependent response on the wafer (122). In some embodiments, the modulation is amplitude modulation. Alternatively, or additionally, the light (318) may be frequency modulated.

[0030] The light (316) from the probe laser (309) is transmitted through the optical fiber (311) to the circulator (313), from the circulator (313) to the wavelength coupler (305) through the optical fiber (307), and from the wavelength coupler (305) to the output coupler (21) through the optical fiber (23). The lens of the output coupler (21) focuses the light (316) to the inspection point. A portion of the light (316) is reflected from the inspection point, and the intensity of this reflection changes over time and changes in a manner influenced by the light (318) of the pump laser (301) in relation to the characteristics of the wafer (122) at the inspection point. The reflected light (316) is collected by the lens of the output coupler (21) and transmitted from the output coupler (21) to the wavelength coupler (305) through the optical fiber (23), from the wavelength coupler (305) to the circulator (313) through the optical fiber (307), and from the circulator (313) to the photodetector (317) through the optical fiber (315). The optical fibers (23, 303, 307, 311 and 315), the wavelength coupler (305), the circulator (313), and the output coupler (21) form an optical circuit.

[0031] FIG. 4 provides a drawing of an MOR system (300) with the optical fiber removed and additional details for the wavelength coupler (305), the circulator (313), and the output coupler (21) shown. As shown in FIG. 4, the circulator (313) may be a unidirectional mirror that transmits light (316) approaching from the direction of the probe laser (309) and reflects light approaching from the direction of the wavelength coupler (305). The wavelength coupler (305) may be a mirror that reflects the light (316) from the probe laser (309) and transmits the light (318) from the pump laser (301). The output coupler (21) may be a lens at the end of the optical fiber (23) (see FIG. 3).

[0032] The pump laser (301) has a wavelength suitable for generating electron-hole pairs in a semiconductor wafer (122). The semiconductor may be silicon (Si) or other semiconductor materials. In some embodiments, the wavelength is about 1 μm or less. In some embodiments, the frequency is in the blue part of the visible spectrum. In some embodiments, the pump laser (301) is an argon laser and the light (318) has a wavelength of about 0.5 μm. In some embodiments, the pump laser (301) is a laser diode. The laser diode may provide light of about 405 nm, about 785 nm, or other suitable wavelengths. The pump laser (301) is powered by an electronic device that allows the amplitude of the output to be modulated. In some embodiments, the amplitude is modulated at a frequency in the range of about 1 kHz to about 40 kHz. Amplitude modulation in this range may be provided by an inexpensive electronic device. In some embodiments, the amplitude is modulated at a frequency in the range of about 40 kHz to about 1 MHz. Amplitude modulation in this range requires more expensive electronic devices but can provide more information in a shorter amount of time.

[0033] The change in charge carrier concentration caused by the pump laser (301) affects the dielectric constant of the wafer (122) at the inspection point, which in turn affects the refractive index. The pump laser (301) also causes localized heating of the wafer (122) at the inspection point, which also affects the refractive index. Both of these effects vary periodically with amplitude modulation. These periods are out of phase so that information can be extracted from both types of effects.

[0034] The probe laser (309) may operate at a constant amplitude so that the amplitude modulation of the reflected light (316a) at the photodetector (317) can be attributed to the effect of the light (318) of the pump laser (301). The probe laser (309) may generate light of a longer wavelength (lower energy) than the pump laser (301). In some embodiments, the light (316) of the probe laser (309) has a wavelength of about 0.6 μm or more. In some embodiments, the probe laser (309) is a helium-neon laser. In some embodiments, the probe laser (309) is a laser diode.

[0035] FIG. 5 illustrates an exemplary ion implantation system (500) comprising a terminal (102), a beamline (104), and the end station (100). The terminal (102) comprises an ion source (108) powered by a high-voltage power supply (110), and the ion source (108) generates ions that are extracted and formed into an ion beam (112). The beamline (104) filters, shapes, and steers the ion beam (112) to provide an x-direction sweep. A workpiece handler (175) within the end station (100) provides a y-direction sweep. Optionally, the beamline (104) steers the ion beam (112) to provide both an x-direction sweep and a y-direction sweep.

[0036] The ion source (108) may include an arc chamber (114) and an ion extraction assembly (118). A gas containing a species to be injected is supplied to the arc chamber (114). Within the arc chamber (114), electrons are generated from an electron source. The electron source may be a filament or a cathode that is heated by the current of the high-voltage power supply (110) to induce thermionic emission of electrons. The electrons may be induced to generate an arc to ionize a portion of the gas within the arc chamber (114) and generate plasma. A magnetic field may be provided to maintain the plasma in a vortex state. The ions may be controllably extracted from the plasma by the ion extraction assembly (118) and accelerated to beamline energy. The ion extraction assembly (118) may include an electrode (120) that accelerates the extracted ions.

[0037] The beamline (104) may include a mass analyzer (126), a beam shaping and steering system (140), a scanning system (128), and a parallelizer (130). The mass analyzer (126) filters ions according to a charge-to-mass ratio so that the ion beam (112) following the mass analyzer (126) becomes a purified ion beam containing only selected ions. In the illustrated embodiment, the mass analyzer (126) includes a refraction section in which ions are deflected by a magnetic field. Ions with an incorrect charge-to-mass ratio are deflected excessively or insufficiently, so that only ions with a desired charge-to-mass ratio continue along the beamline (104) from the mass analyzer (126).

[0038] The beam shaping and steering system (140) comprises one or more electric or magnetic lenses (148) for compressing and steering the ion beam (112). In some embodiments, the beam shaping and steering system (140) comprises a first quadrupole magnet (x-quad) for compressing the ion beam (112) in the x-direction and a second quadrupole magnet (y-quad) for compressing the ion beam (112) in the y-direction. The y-direction is the ground-inward direction of FIG. 5.

[0039] The scanning system (128) steers the ion beam (112) so that the beam path (112a) of the ion beam (112) sweeps across the x-direction (fast scan direction). The scanning system (128) may include a plate (146). The plate (146) may steer the ion beam (112) electrically or magnetically. In some embodiments, the scanning system (128) periodically sweeps the beam path (112a) at a speed of about 1 kHz or more. The sweep in the y-direction (slow scan direction) is performed at a slower speed, for example, about 100 Hz or less.

[0040] The scanned ion beam (112) may pass through a parallelizer (130). In the illustrated embodiment, the parallelizer (130) includes two dipole magnets (154). The two dipole magnets (154) are substantially trapezoidal in shape and oriented mirror-symmetrically with respect to each other so as to refract the beam path (112a) into an S-shape. The parallelizer (130) has the effect of making all beam paths (112a) substantially parallel.

[0041] The ion beam (112) is received at the end station (100). Optionally, a deceleration stage (156) is provided within the end station (100) downstream of the paralleler (130). The deceleration stage (156) may include one or more electrodes (158) that decelerate the ion beam (112) and focus the ion beam (112) into a converging flow. In some embodiments, the beamline (104) is maintained at a first potential and the deceleration stage (156) is maintained at a second potential, the first potential corresponds to the beamline energy and the second potential corresponds to the injection energy. The device for focusing the ion beam (112) may be integrated with the device for decelerating the ion beam (112). In some embodiments, the deceleration stage (156) includes an Einzel lens.

[0042] A control system (168) is provided to control, communicate with, and / or coordinate the ion source (108), the mass spectrometer (126), the scanning system (128), the deceleration stage (156), and the workpiece handler (175). The control system (168) may also control the wafer transfer system (11) and the wafer inspection system (20) (see FIG. 1) or communicate with one or more similar control systems provided for the wafer transfer system (11) and the wafer inspection system (20). The control system (168) may include a computer comprising a central processing unit and a memory system programmed with commands to operate these and other components of the ion implantation system (500). For example, the control system (168) may determine the ion generation rate of the ion source (108), beamline energy, fast scan rate, implantation energy, and slow scan rate. The control system (168) may receive a set of operating parameters that constitute a recipe, which can instruct an operator to perform a specific and reproducible ion implantation operation on the ion implantation system (500). The control system (168) may operate the wafer transfer system (11) to maximize throughput and may analyze data from the wafer inspection system (20) and, if applicable, respond accordingly.

[0043] FIG. 6 illustrates an end station (600) according to a different embodiment. The end station (600) is similar to the end station (100) of FIG. 1, but differs in that the wafer inspection system (20) in the end station (600) is configured to inspect the wafer (122) while the wafer (122) is inside the first load lock chamber (17B). The optical fiber (23) may pass through a vacuum seal port at the top of the first load lock chamber (17B) such that the output coupler (21) is inside the first load lock chamber (17B) and the component (19) is outside the first load lock chamber (17B). In some embodiments, the component (19) is attached to the side of the first load lock chamber (17B).

[0044] As illustrated in FIG. 6, the end station (600) may include a second wafer inspection system (620) installed within the second load lock chamber (17A). The second wafer inspection system (620) is provided to inspect the wafer (122) after the ion implantation. The output coupler (21) of the second wafer inspection system (620) may be positioned to inspect the wafer (122) at the same point as the wafer inspection system (20) to facilitate comparison between the data of the second wafer inspection system (620) and the data of the wafer inspection system (20). The point is at an angular distance (601) from the alignment mark (26).

[0045] FIG. 7 illustrates an end station (700) according to a different embodiment. The end station (700) is similar to the end station (100) of FIG. 1, but differs in that the wafer inspection system (20) in the end station (700) is configured to inspect the wafer (122) while the wafer (122) is being secured by the second robot (27B) or another robot of the wafer transfer system (11). In some embodiments, the component (19) is located within the front end module (29). In some embodiments, the component (19) is located outside the front end module (29), and the optical fiber (23) passes through the wall of the front end module (29) as shown in FIG. 7.

[0046] The robot (27B) may have any suitable structure. FIG. 8 illustrates the configuration of the second robot (27B) according to some embodiments. As illustrated in FIG. 8, the second robot (27B) includes a base (807), three pivot joints (809), two arms (801), and an effector (803). The effector (803) may have an arc groove (805) for supporting the wafer (122) at the periphery. In some embodiments, the arms (801) may be raised or lowered relative to the base (807). These features or similar features allow the second robot (27B) to place the wafer (122) under the output coupler (21) (see FIG. 7) so that the wafer (122) can be inspected while being held by the effector (803). Instead of the mechanical effector (803) above, the second robot (27B) may have an electrostatic chuck, a vacuum chuck, or other device that fixes or supports the wafer (122) while it is moved by the second robot (27B). The robots (27A, 15A and 15B) may have similar configurations.

[0047] FIG. 9 illustrates an end station (900) according to a different embodiment. The end station (900) is similar to the end station (100) of FIG. 1, but differs in that the wafer inspection system (20) in the end station (900) is configured to inspect the wafer (122) while the wafer (122) is secured by the workpiece handler (175). In some embodiments, the component (19) is inside the process chamber (13). In some embodiments, the component (19) is outside the process chamber (13), and the optical fiber (23) passes through the wall of the process chamber (13) as shown in FIG. 9.

[0048] FIGS. 10A-10C illustrates embodiments of a workpiece handler (175) according to some embodiments. As illustrated in FIGS. 10A-10C, the workpiece handler (175) comprises a base (1001), an arm (1005), an arm (1007), and a chuck (1009). The chuck (1009) may be a mechanical chuck, an electrostatic chuck, a vacuum chuck, or another type of chuck suitable for holding the wafer (122) during ion implantation. The chuck (1009) is pivotally connected to the arm (1007) via a joint (1011). The arm (1007) is pivotally connected to the arm (1005) via a joint (1013). The arm (1005) is pivotally connected to the base (1001) via a joint (1003).

[0049] As illustrated in FIG. 10A, the wafer (122) may be facing the y-direction when received by the third robot (15B) (see FIG. 9). The y-direction may be a vertical direction. The wafer (122) may be inspected while in this direction.

[0050] As illustrated in FIG. 10B, the wafer (122) can be rotated around the joint (1011) so that the wafer (122) is oriented toward the injection plane (compare with FIG. 5). The injection plane is selected according to the desired orientation of the wafer (122) relative to the beam path (112a). The beam path (112a) is the z-direction, and in the embodiments illustrated in FIG. 10B and FIG. 5, the injection plane is set to be perpendicular to the z-direction. Optionally, the injection plane is set to be at an angle to the z-direction. As illustrated in FIG. 10C, by coordinated rotation around the joints (1003, 1011 and 1013), the wafer (122) can be swept in the y-direction while the wafer (122) is oriented toward the injection plane.

[0051] FIG. 11 provides a flowchart of a method (1100) that can be implemented using an ion implantation system (500) and one of an end station (100, 600, 700, or 900). Although the method (1100) is illustrated and described below as a series of actions or events, it will be understood that the illustrated order of such actions or events should not be interpreted in a limiting sense. For example, some actions may occur in a different order and / or simultaneously with other actions or events apart from those illustrated and / or described herein. Furthermore, not all illustrated actions may be required to implement one or more aspects or embodiments of the description herein.

[0052] The above method (1100) may begin with an operation (1101), namely, removing a wafer from a wafer carrier. FIG. 1 provides an embodiment in which a first robot (27A) of the front end module (29) performs this operation. Alternatively, the wafer carrier (35) is transferred into the process chamber (13), and this operation is performed in the process chamber (13).

[0053] Operation (1103) is to place the wafer on the aligner. Operation (1105) is to set the wafer alignment using the aligner.

[0054] Operation (1107) is to inspect the wafer. In some embodiments, the inspection is performed via an optical fiber. In some embodiments, the inspection includes MOR inspection. In some embodiments, the inspection is performed while the wafer is on the aligner. FIG. 1 provides an example of an end station enabling this embodiment. In some embodiments, the wafer is rotated on the aligner and the inspection is repeated. In some embodiments, the inspection is performed after the wafer is aligned. In some embodiments, the inspection is performed while the wafer is in a load lock chamber. FIG. 6 provides an example of an end station enabling this embodiment. In some embodiments, the inspection is performed while the wafer is in a gripping state of a robot. FIG. 7 provides an example of an end station enabling this embodiment. In some embodiments, the inspection is performed while the wafer is secured by the workpiece handler. FIG. 9 provides an example of an end station enabling this embodiment.

[0055] Operation (1109) is to move the wafer to the load lock chamber. Operation (1111) is to exhaust the load lock chamber. Operation (1113) is to move the wafer from the load lock chamber to the workpiece handler. Operation (1115) is to perform ion implantation on the wafer while the wafer is secured by the workpiece handler.

[0056] Operation (1117) is an optional step of performing a second inspection of the wafer after the ion implantation. The second inspection may be performed in the process chamber, the load lock chamber, or the front end module.

[0057] Operation (1119) is to move the wafer from the workpiece handler to the load lock chamber. Operation (1121) is to pressurize the load lock chamber. Operation (1123) is to move the wafer from the load lock chamber to the wafer carrier. The wafer carrier may be the same wafer carrier from which the wafer was taken or a different wafer carrier.

[0058] Operation (1125) is to make a diagnostic decision based on data obtained using operation (1107) prior to the ion implantation of operation (1115). In some embodiments, the diagnostic decision relates to the wafer state prior to the ion implantation. In some embodiments, the diagnostic decision involves comparing the data with reference data previously obtained by inspecting one or more other wafers. In some embodiments, the diagnostic decision involves determining the free carrier concentration at the inspection point. For example, parameters required to apply a Drude model to determine the free carrier concentration can be obtained from the MOR data.

[0059] In some embodiments, the diagnostic determination includes an evaluation of the degree of amorphization. For example, MOR data provides peaks corresponding to bandgap energies. If the material has a highly ordered crystal structure, these peaks are sharp. As amorphization increases, these peaks become more spread out.

[0060] In some embodiments, the diagnostic decision includes additionally using data obtained using operation (1117), which is a second test performed after the ion implantation of operation (1115). In this case, the diagnostic decision can evaluate the effect of operation (1117) in obtaining a desired result.

[0061] Operation (1127) is an optional operation that performs some action based on the diagnostic decision. In some embodiments, operation (1127) modifies the parameters of the ion implantation of operation (1115). For example, the dose of the ion implantation may be increased or decreased based on the inspection results. In some embodiments, the modification is applied to the inspected wafer. Alternatively, or additionally, the modification may be applied to ion implantation performed on other wafers. In some embodiments, corrective measures other than modifying the ion implantation of operation (1115) for the inspected wafer based on the diagnostic decision are taken. In some embodiments, the ion implantation of operation (1115) for the inspected wafer based on the diagnostic decision is bypassed. For example, the ion implantation may be deferred until the wafer is cleaned or returned to an upstream process that is not properly completed. The upstream process may be another ion implantation process used for either doping or damage engineering. In some embodiments, the wafer is optionally discarded based on the diagnostic decision.

[0062] In some embodiments, a process upstream of the ion implantation system is modified based on the diagnostic decision. For example, the conditions of a previous ion implantation process for either doping or damage engineering may be modified based on the diagnostic decision.

[0063] The foregoing describes the features of various embodiments to enable a person skilled in the art to better understand the aspects of the present disclosure. A person skilled in the art should recognize that the present disclosure can be readily used as a basis for designing or modifying other processes and structures to perform the same purpose and / or achieve the same advantages of the embodiments described herein. A person skilled in the art should also recognize that such equivalent configurations may be subject to various changes, substitutions, and variations without departing from the spirit and scope of the present disclosure. Furthermore, even if a particular feature is disclosed with respect to only one of the embodiments, such feature may be combined with one or more other features of other embodiments that may be desirable or advantageous for a given application.

Claims

Claim 1 An ion implantation system comprising: an ion source configured to generate an ion beam; a beamline configured to guide the ion beam; an end station positioned to receive the ion beam; a workpiece handler within the end station—the workpiece handler is configured to move a wafer into the path of the ion beam while securing it on a chuck—; a wafer transport system within the end station—the wafer transport system is configured to move the wafer from a wafer carrier to the workpiece handler—; and a wafer inspection system including an optical fiber and a lens—the wafer inspection system is configured to inspect the wafer through the optical fiber while the wafer is in transit from the wafer carrier into the path of the ion beam—; an ion implantation system comprising. Claim 2 In claim 1, the wafer inspection system is an ion implantation system positioned to inspect the wafer while the wafer is being handled by the wafer transfer system. Claim 3 In paragraph 2, the wafer inspection system is an ion implantation system positioned to inspect the wafer while the wafer is in a load lock chamber. Claim 4 In paragraph 2, the wafer inspection system is an ion implantation system positioned to inspect the wafer while the wafer is on an aligner. Claim 5 In paragraph 4, an ion implantation system in which a component of the wafer inspection system is mounted on the aligner. Claim 6 In claim 1, the wafer inspection system is an ion implantation system positioned to inspect the wafer while the wafer is fixed by the workpiece handler. Claim 7 In claim 1, the end station includes a vacuum chamber, and the wafer inspection system is an ion implantation system positioned to inspect the wafer while the wafer is inside the vacuum chamber. Claim 8 In claim 1, the wafer inspection system is an ion implantation system comprising a modulated optical reflectance system. Claim 9 An ion implantation system according to claim 1, wherein the wafer carrier is a front opening unified pod. Claim 10 An ion implantation system according to claim 1, wherein the wafer inspection system further comprises a first laser, a second laser, and a wavelength coupler, wherein the wavelength coupler is configured to guide both the light of the first laser and the second laser into the optical fiber. Claim 11 An ion implantation system comprising: an ion source configured to generate an ion beam; a beamline configured to guide the ion beam; an end station positioned to receive the ion beam; a workpiece handler within the end station—the workpiece handler is configured to secure a wafer in the path of the ion beam—; a wafer transfer system including an aligner—the wafer transfer system is configured to set the orientation of the wafer using the aligner and to transfer the wafer from the aligner to the workpiece handler—; and a wafer inspection system including an optical fiber—the wafer inspection system is positioned to inspect the wafer through the optical fiber while the wafer is on the aligner—; an ion implantation system comprising Claim 12 In claim 11, an ion implantation system in which a component of the wafer inspection system is mounted on the aligner. Claim 13 A method for operating an ion implantation system, comprising: a step of picking a wafer from a wafer carrier using a wafer transfer system that is part of the ion implantation system; a step of placing the wafer on an aligner; a step of setting the alignment of the wafer; a step of performing a first inspection on the wafer to obtain first inspection data; a step of transferring the wafer from the aligner to a workpiece handler of the ion implantation system; and a step of performing ion implantation on the wafer after performing the first inspection and while the wafer is fixed by the workpiece handler. Claim 14 In paragraph 13, a method in which the first inspection is performed (takes place) while the wafer is on the aligner. Claim 15 A method according to claim 14, wherein the first inspection is performed while the wafer is on the aligner and after the alignment setting of the wafer. Claim 16 In claim 14, the first inspection comprises inspecting the wafer while the wafer is in a first direction, and the method further comprises performing a second inspection on the wafer while the wafer is in a second direction. Claim 17 A method according to claim 13, further comprising: a step of performing a second inspection of the wafer after the ion implantation to obtain second inspection data; and a step of providing a diagnostic determination based on a comparison between the first inspection data and the second inspection data. Claim 18 In paragraph 13, the above-mentioned first test comprises modulated optical reflectance spectroscopy. Claim 19 In claim 18, the modulated light reflectance spectroscopy method comprises coupling the output of a pump laser and the output of a probe laser into an optical fiber using a wavelength coupler, and focusing the output of the pump laser and the output of the probe laser on an inspection point on the wafer. Claim 20 In paragraph 13, the method wherein the ion implantation is carried out under conditions set based on the first test data.

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