Warp and tilt verification using diffraction patterns

Abstract

A light source directs an incident beam at an oblique angle at a surface of a workpiece on a stage. The detector images a diffraction pattern of the incident beam reflected from the workpiece. At least one of a twist angle and an inclination angle of the workpiece on the stage is determined based on the diffraction pattern. The workpiece may be a semiconductor wafer, and the stage may be, for example, part of an ion implanter.

Description

[0001] Cross-references to related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 540,255, filed and assigned on September 25, 2023, the disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to process control during workpiece machining. Background Technology

[0003] In semiconductor device manufacturing, ion implantation is used to dope semiconductors with impurities. Ion implantation systems are typically used to implant ions from an ion beam into a workpiece (such as a semiconductor wafer) to produce n-type or p-type doped material, or to form a passivation layer during integrated circuit manufacturing. This beam treatment selectively implants impurities containing specified dopant materials into the workpiece at predetermined energy levels and controlled concentrations to produce semiconductor materials during integrated circuit manufacturing. When used to dope semiconductor wafers, the ion implantation system implants selected ion species into the workpiece to produce the desired intrinsic material. For example, implanting ions from source materials such as antimony, arsenic, or phosphorus results in an "n-type" intrinsic material wafer, while a "p-type" intrinsic material wafer is typically generated from ions from source materials such as boron, gallium, or indium.

[0004] A typical ion implanter includes an ion source, an ion extraction unit, a mass analysis unit, a beam transport unit, and a wafer processing unit. The ion source generates ions of the desired atomic or molecular dopant species. These ions are extracted from the ion source by an extraction system (typically a set of electrodes) that excites and directs the ion stream from the ion source, forming an ion beam. The desired ions are separated from the ion beam in the mass analysis unit, typically by mass dispersion or separation of the extracted ion beam using magnetic dipoles. The beam transport unit is typically a vacuum system containing a series of focusing devices that transports the ion beam to the workpiece processing unit while maintaining the desired characteristics of the ion beam. Finally, the semiconductor wafer is moved into or out of the processing chamber via a workpiece handling system (which may include one or more robotic arms) to place the workpiece to be processed in front of the ion beam and remove the processed workpiece from the ion implanter. Summary of the Invention

[0005] In a first embodiment, a system is provided. The system includes: a chamber; a stage configured to hold a workpiece; a light source configured to guide an incident light beam to a surface of the workpiece on the stage; a detector configured to image a diffraction pattern of the incident light beam reflected from the workpiece; and a processor in electronic communication with the detector. The stage is disposed within the chamber. The incident light beam is guided at an oblique angle to the surface of the workpiece. The processor is configured to determine at least one of a twist angle and a tilt angle of the workpiece on the stage based on the diffraction pattern. The detector may be a camera, and the stage may be an electrostatic chuck. The light source may be a laser, and the incident light beam may be predominantly red light. The incident light beam may have a diameter of 0.5 mm to 0.7 mm. The incident light beam may be incident on the workpiece at an angle of 30° to 60°.

[0006] In one example, the chamber has a base. The stage can be configured to keep the workpiece parallel to the inner surface of the base. The stage can also be configured to keep the workpiece perpendicular to the inner surface of the base.

[0007] In one example, the chamber has a chamber surface. An incident light beam can be reflected from the workpiece onto the chamber surface. A diffraction pattern can be imaged on the chamber surface by a detector. The detector can also directly receive the incident light beam reflected from the workpiece.

[0008] Determining at least one of the twist angle and tilt angle may include determining the displacement of the center of the diffraction pattern. Determining at least one of the twist angle and tilt angle may also include determining the curvature of the diffraction pattern and determining the center of the workpiece.

[0009] The processor can be further configured to analyze the speckle pattern of the diffraction pattern to determine the surface measurement results of the workpiece.

[0010] In a second embodiment, a method is provided. The method includes: guiding an incident light beam from a light source to a workpiece on a stage in a chamber, the incident light beam being guided at an oblique angle to the surface of the workpiece; reflecting the incident light beam from the surface of the workpiece; imaging a diffraction pattern of the incident light beam reflected from the workpiece; and using a processor to determine at least one of a twist angle and a tilt angle of the workpiece on the stage based on the diffraction pattern. The workpiece may be a patterned semiconductor wafer. The light source may be a laser and the incident light beam may be predominantly red light. The incident light beam may have a diameter of 0.5 mm to 0.7 mm. The incident light beam may be incident on the workpiece at an angle of 30° to 60°.

[0011] The method may include twisting and / or tilting a workpiece on a stage based on a torsion angle and / or a tilt angle.

[0012] Determining at least one of the twist angle and tilt angle may include determining the center offset of the diffraction pattern. Determining at least one of the twist angle and tilt angle may also include determining the curvature of the diffraction pattern and determining the center of the workpiece.

[0013] This method may include using a processor to analyze the speckle pattern of the diffraction pattern to determine the surface measurement results of the workpiece.

[0014] In a third embodiment, a non-transitory computer-readable storage medium is disclosed. The non-transitory computer-readable storage medium includes one or more programs for performing the following steps on one or more computing devices: receiving a diffraction pattern of an incident light beam reflected from the surface of a workpiece on a stage, the incident light beam being guided at an oblique angle to the workpiece surface; and determining at least one of a twist angle and a tilt angle of the workpiece on the stage based on the diffraction pattern. Attached Figure Description

[0015] For a more complete understanding of the nature and purpose of this disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of an exemplary system for determining the torsion angle and tilt angle of a workpiece according to the present disclosure; Figure 2 This is a schematic diagram of another exemplary system for determining the torsion angle and tilt angle of a workpiece according to the present disclosure; Figure 3 This is a schematic diagram of another exemplary system for determining the torsion angle and tilt angle of a workpiece according to this disclosure; Figure 4 This is a flowchart of the method according to this disclosure; Figure 5 It is an image of an exemplary diffraction pattern; Figure 6 Figure 7 , Figures 8A to 8G as well as Figures 9A to 9G Test data from different workpiece samples are shown; and Figure 10 This is a block diagram of an exemplary vacuum system utilizing an ion source with a target material according to the present disclosure. Detailed Implementation

[0016] Although the claimed subject matter will be described with reference to certain embodiments, other embodiments, including those that do not provide all the benefits and features set forth herein, are also within the scope of this disclosure. Various structural, logical, processing, and electronic modifications may be made without departing from the scope of this disclosure. Therefore, the scope of this disclosure is defined only by reference to the appended claims.

[0017] A stage (such as an electrostatic chuck) is used to hold the workpiece in the path of the ion beam. The twist and tilt angles of the workpiece relative to the ion beam are set to ensure the beam strikes the workpiece surface at the correct angle. The placement of the workpiece on the electrostatic chuck is critical for dose uniformity. For some implantations, such as high-energy implantation, the ion beam is aligned with the channel direction of the silicon. This type of high-energy implantation may require an angular accuracy of at least 0.05 degrees. Warpage (especially common on thin workpieces) can affect the angular distribution of the ion beam as it enters the workpiece surface. Wafer warpage can affect the final dose or angular accuracy of the implanted material.

[0018] Typically, multiple injection patterns are required on the same workpiece. In such cases, high precision must be maintained not only during a single injection step but also across multiple injection steps. For three-dimensional structures, precision is even more critical because incorrect alignment can lead to shading effects. Shading effects can cause inaccurate injection dosage at desired locations.

[0019] If multiple implantation processes are performed on the workpiece, the workpiece may be transferred between the load lock and the stage multiple times, potentially introducing positioning errors in the x, y, and angular directions on the stage. The stage itself may also be incorrectly positioned or calibrated, further affecting workpiece alignment. Alignment errors in the workpiece will adversely affect the ion implantation results. Similar effects can occur if the workpiece is improperly positioned during deposition, etching, or other processes.

[0020] In processing chamber environments with high vacuum, extreme temperatures, and stringent cleanliness requirements, it is difficult to determine torsion and tilt using sensors on a stage. However, the inventors recognized and understood that a beam of light projected onto a workpiece (such as a semiconductor wafer or other substrate) can be used to determine the workpiece's torsion and tilt on the stage. Light reflected from the workpiece's surface produces a diffraction pattern. This technique avoids the problems caused by improperly calibrated sensors on the stage. It also avoids the need for complex sensors in environments with potentially extreme temperatures, vacuum conditions, and / or stringent cleanliness requirements. Measurement and alignment can be performed using features printed on the top surface of the workpiece, which is the surface the ion beam will interact with.

[0021] The patterned workpiece is directional in terms of the surface or subsurface structure array of integrated circuits. When a beam of light is focused at an incident angle onto the workpiece having an array of integrated circuit features, a characteristic diffraction pattern is produced. The integrated circuit features can be repeated over an area comparable in size to the incident beam. For example, the workpiece may include a storage device or other device. The array may be photoresist lines or other structural features on or within the workpiece. The diffraction pattern may be, for example, scattering spots. These spots may be fitted with circular and / or linear shapes along the XY directions. Even with small changes in torsion (e.g., 0 ± 1°), the diffraction pattern will show a corresponding XY offset. The offset of the main reflection spot along the X and Y axes corresponds to any tilt change from a reference tilt position (e.g., 0 ± 1°). Using this offset of the best-fit line, circle, or spot position, the workpiece position can be adjusted on the stage for the first workpiece in a batch. The system can monitor and readjust accordingly for the remaining workpieces in the batch during operation. Individual corrections can also be performed for each workpiece. The X and Y axes refer to the vertical plane orientation of the workpiece or the stage holding the workpiece.

[0022] It should be noted that unpatterned workpieces do not produce any diffraction patterns and are therefore generally unsuitable for determining torsional accuracy and readjustment. However, the location of the principal reflection spot along the XY axis can be used to confirm and adjust the workpiece's tilt.

[0023] Figure 1This is a schematic diagram of a system 100 for determining a torsion angle 109 and a tilt angle 110 of a workpiece 103 according to some embodiments. The workpiece 103 may be a silicon wafer, a silicon carbide (SiC) wafer, a gallium nitride (GaN) wafer, or other types of workpieces. The torsion angle 109 may be measured relative to a desired position of a notch or flat portion on the workpiece 103 and a notch or flat portion on the stage 102. The torsion angle 109 is measured in an XY plane perpendicular to the Z-axis. The Z-axis may extend upward from and be perpendicular to the flat surface of the stage 102 or the workpiece 103. Therefore, the actual angular position of a notch, flat portion, or other desired point on the workpiece 103 may be rotated relative to the stage 102. The tilt angle 110 may be measured relative to the stage 102. The tilt angle 110 may include an angular difference caused by the workpiece 103 not being placed flat on the surface of the stage 102. Therefore, a tilt angle of 110° means that the workpiece 103 is not flat in the XY plane of the stage 102, or is at least partially raised in the Z direction. System 100 includes a chamber 101 having a chamber surface 106. Chamber 101 may be, for example, a terminal station, as included in an ion implantation system described in further detail below. Chamber 101 may also be a processing chamber or other chamber including a stage 102 for supporting the workpiece 103. Chamber 101 can operate under reduced pressure, vacuum, atmospheric pressure, or pressures above atmospheric pressure. For implantation applications, chamber 101 operates under vacuum.

[0024] exist Figure 1 In the example, chamber surface 106 is the wall of chamber 101. Chamber surface 106 can be clean and relatively polished. Chamber surface 106 can be planar or curved. Chamber surface 106 can be curved if it is known how the angles of chamber surface 106 vary with size (e.g., height or lateral position). The wall of chamber 101 can be cleaned during preventative maintenance to ensure proper imaging. However, particles or other materials on the wall of chamber 101 can be compensated for during or after imaging. In the example, dark particles on the wall of chamber 101 can improve the contrast of the resulting image.

[0025] In this example, a baffle (not shown) may be used to protect the chamber surface 106 and keep it clean. This baffle may cover the chamber surface 106 when it is not being used for measurement.

[0026] like Figure 1 As further shown, the stage 102 is positioned within the chamber 101. The stage 102 may be, for example, an electrostatic chuck. Alternatively, the stage 102 may be a chuck that physically holds the workpiece 103, a vacuum chuck, or a stage 102 on which the workpiece 103 is placed by gravity. The stage 102 may be moved, for example, along the X, Y, and / or Z axes using an actuator 113.

[0027] Light source 104 guides incident light beam 105 to the surface of workpiece 103 on stage 102. Incident light beam 105 is guided to the surface of workpiece 103 at an angle of incidence (θ) greater than 0° and less than 90°, including all angles and ranges therebetween. In one embodiment, angle θ may be in the range of about 5° to 85°. In another embodiment, angle θ may be in the range of about 10° to 80°. In yet another embodiment, angle θ may be in the range of about 30° to 60° or about 30° to 45°. In one example, angle θ may be approximately 45°.

[0028] In one example, light source 104 is a laser that primarily produces red light. Experiments show that red light provides a better diffraction pattern compared to other visible wavelengths, while other visible wavelengths provide acceptable diffraction patterns. Besides red light, light source 104 can also be a laser that primarily produces blue or green light. In another example, light source 104 can be a laser that produces light within or across the visible wavelength range. In yet another example, light source 104 can be a laser that produces wavelengths outside the visible spectrum or wavelengths within and outside the visible spectrum.

[0029] In one example, the incident beam 105 has a diameter of approximately 0.5 mm to 0.7 mm. The diameter of the incident beam 105 can be selected based on the device size on the workpiece 103 or other features of the workpiece 103. However, a larger diameter incident beam 105 can be used to direct it onto a greater number of devices or features on the workpiece 103, which may be helpful in determining alignment, as more integrated circuit patterns defined on the workpiece 103 will contribute to the final diffraction pattern 108. For example, the incident beam 105 can have a diameter up to approximately 10 mm. The area of ​​the workpiece 103 sampled by the incident beam 105 can have a reflective structure to produce a strong diffraction effect, but can have a spacing that dominates in the X and Y directions. Therefore, the optimal diameter of the incident beam 105 can vary between workpieces to provide this diffraction effect. For example, if the integrated circuit patterns defined on the workpiece 103 are large, a larger incident beam 105 can be used. A larger incident beam 105 can also be used with a smaller integrated circuit pattern defined on the workpiece 103, as the additional structure provides a better diffraction effect.

[0030] like Figure 1 As further shown, detector 107 is configured to image the diffraction pattern 108 of the incident light beam 105 reflected from workpiece 103. The diffraction pattern 108 is reflected onto the chamber surface 106. In one embodiment, detector 107 may be physically located inside chamber 101 (e.g., Figure 1(Illustrated), or alternatively, may be located outside chamber 101 (e.g., positioned to image the diffraction pattern 108 through a window (not shown) in chamber 101). In one example, detector 107 is a camera or photodiode. In one example, detector 107 is capable of imaging diffraction pattern variations of less than 0.01°.

[0031] Figure 5 This is an image of an exemplary diffraction pattern 251 of a patterned semiconductor wafer, which is an example of a workpiece suitable for use in the embodiments disclosed herein. The diffraction pattern 251 may differ from other patterns based on, for example, the workpiece's location, shape, design, and features. Figure 5 The diffraction pattern shown is superimposed on... Figure 5 The vertical lines of the diffraction pattern 251 on the grid shown are aligned with the notches on the workpiece. The dimensions of the patterned features on the workpiece affect the spacing of these vertical lines in the diffraction pattern 251. If the location of the notch on the patterned semiconductor wafer is known, the patterned semiconductor wafer can be rotated, for example, to adjust the torsion angle. Other adjustments or operations described herein may also be performed.

[0032] Back Figure 1 The processor 111 communicates electronically with the detector 107. The processor 111 can be configured to determine the torsion angle 109 and tilt angle 110 of the workpiece 103 on the stage 102 based on the diffraction pattern 108. The processor 111 may include a programmable processor programmed via software and / or firmware to perform the functions described herein, and is equipped with suitable digital and / or analog interfaces for connection to other components of the system 100. Alternatively or additionally, the processor 111 includes hardwired and / or programmable hardware logic circuitry that performs at least a portion of the functions of the processor 111. Although in Figure 1 Processor 111 is shown in the figure, but for simplicity, processor 111 is shown as a single integral functional block. However, in practical applications, processor 111 may include multiple interconnected control units with suitable interfaces for receiving and outputting the signals shown in the figures and described in the text. Program code or instructions for enabling processor 111 to perform the various methods and functions disclosed herein may be stored in a readable storage medium, such as memory within processor 111 or other memory.

[0033] exist Figure 1 In one embodiment, the chamber has a base 112 (illustrated at...). Figure 1 Below the bottom stage 102. The base 112 can be, for example, the floor of the processing chamber. The stage 102 is configured to hold the workpiece 103 such that the workpiece 103 is parallel to the inner surface of the base. Therefore, gravity can play an auxiliary role when the workpiece 103 is held on the stage 102. Therefore, gravity is oriented in... Figure 1 On the Z-axis.

[0034] Figure 4 This is a flowchart of method 200. Method 200 can be performed in any embodiment of the system disclosed herein, such as system 100. In step 201, an incident light beam 105 is guided from a light source 14 to a workpiece 103 on a stage 102 in a chamber 101. The incident light beam 105 is guided at an oblique angle to the surface of the workpiece 103. The incident light beam 105 can be a red laser beam or a laser beam having one or more other wavelengths. In one example, the incident light beam 105 is incident on the workpiece at an angle greater than 0° and less than 90°, such as about 5° to 85°, about 10° to 80°, about 30° to 60°, or about 30° to 45°. The stage 102 can hold the workpiece 103 in a horizontal or vertical position. In one example, the workpiece 103 is a patterned semiconductor wafer. Other workpieces 103 are also possible.

[0035] In step 202, the incident light beam 105 is reflected from the surface of the workpiece 103. In step 203, the diffraction pattern 108 of the incident light beam 105 reflected from the workpiece 103 is imaged. The diffraction pattern 108 may be projected onto the chamber surface 106 in the chamber 101 containing the workpiece 103, or onto the detector 107 itself.

[0036] In step 204, the processor 111 determines at least one of the twist angle and tilt angle of the workpiece 103 on the stage 102 based on the diffraction pattern. The diffraction pattern (e.g., Figure 5 The curvature of the diffraction pattern 251 can be used to find the center of workpiece 103. The tangent to the circle at the center can be horizontal. If this tangent is known, the center of workpiece 103 can be determined because the radius of workpiece 103 is perpendicular to the tangent of the curvature that contacts workpiece 103. In another example, the circle is fitted to the curvature (such as, for example...) Figure 5 (The curved portion of the diffraction pattern 251 in the image), and compare the center of the fitted circle with the vertical line to find the center of the workpiece 103.

[0037] According to Figure 1 The tilt is determined by the central spot of the diffraction pattern 108. Figure 5 The value is marked as 250. In Figure 5 In this configuration, the light spot 250 is part of the diffraction pattern 251. Tilting the workpiece 103 toward or away from the light source will shift the light spot downwards or upwards. Tilting to the left will shift the light spot to the left. Tilting to the right will shift the light spot to the right. Twisting will cause the x-axis of the diffraction pattern to become non-orthogonal to the plane of the light ray, workpiece 103, and / or detector, because the axis will shift out of that plane. In one embodiment, the central light spot is measured relative to a reference point, which may be established during the alignment step. Figure 5The thicker crosshairs on the grid indicate exemplary reference points.

[0038] For the unpatterned workpiece 103, the tilt angle can affect the offset of the central spot in the XX or YY direction, which can be used to confirm the tilt. For the patterned workpiece 103, twisting and tilting can affect the offset of the diffraction pattern, which can be used to confirm the twisting and tilting.

[0039] The shape of the light spot, for example Figure 5 Example 250 in the diagram can also be used to determine tilt. The position of the light spot can be used to determine the position in the Z direction (e.g., the height of the stage or other platform 102). If the stage or other platform 102 is, for example, flipped into the ion beam path, its height may not affect workpiece handling. However, the height of the stage or other platform 102 can be used to diagnose robot positioning errors used during stage placement.

[0040] The workpiece 103 on stage 102 can be torsional and / or tilted based on a torsion angle and / or tilt angle. This adjustment can be used as a form of process control. For example, one or more actuators 113 within or connected to stage 102 can torsion and / or tilt the workpiece to align it to specifications. In one example, the workpiece 103 is torsion and / or tilted until the diffraction pattern 108 is flat. However, such torsion and / or tilt adjustments are not always performed. After determining the relationship between pattern offset and torsion, implantation can then be performed based on the determined relationship. The position of the ion beam and / or stage 102 can compensate for any deviation of the workpiece 103 on stage 102 from the desired torsion and / or tilt position. For example, if the workpiece 103 is not in the desired position or angle on stage 102, the position of stage 102 can be adjusted to move the workpiece 103 to the desired position or angle.

[0041] The torsion and / or tilt of workpiece 103 on stage 102 can be continuously adjusted. For example, the torsion angle and / or tilt angle of workpiece 103 can be measured simultaneously with the torsion and / or tilt angle. Stage 102 can be moved until the torsion and / or tilt of the workpiece meets the desired specifications. The torsion and / or tilt of workpiece 103 on stage 102 can also be performed sequentially, for example, between the injection of workpiece 103 or different workpieces 103. In one example, the torsion and / or tilt of workpiece 103 on stage 102 can be performed periodically, for example, between alternating workpieces 103 or for a portion of workpieces 103 in a batch.

[0042] In addition to adjusting the stage 102, torsion angle and / or tilt angle adjustment tools can also be used. For example, ion beam optics upstream of the stage 102 can be adjusted based on the torsion angle and / or tilt angle. In one example, the beam guiding device can be adjusted based on the torsion angle and / or tilt angle. The ion source can also be adjusted based on the torsion angle and / or tilt angle.

[0043] Workpiece 103 may be scrapped based on its torsion angle and / or tilt angle. If the torsion angle and / or tilt angle are incorrect or outside the specification range, workpiece 103 may be scrapped. This can save manufacturing costs if workpiece 103 cannot be compensated for during subsequent processing or additional injection.

[0044] The torsion and / or tilt function of the stage 102 can be checked using the measured torsion and / or tilt angles. The measurement results of the torsion and / or tilt of the workpiece 103 can be compared with the specifications. This can be performed as part of the initialization or process control steps during the injection operation. If the torsion and / or tilt angles exceed the specification range, a system interlock can be used to prevent operation.

[0045] Depending on the torsion angle and / or tilt angle, workpiece 103 can be returned to the aligner for repositioning. The aligner can reposition workpiece 103 instead of adjusting the stage 102. When workpiece 103 is not on the stage, the aligner can rotate it. As workpiece 103 moves into or out of the stage 102, one or more robots can adjust its placement on the stage 102.

[0046] The degree of warpage of workpiece 103 can be based on the light spot (e.g. Figure 5 The degree of warpage can be determined using Example 250. It can be used during the processing of certain warp-prone workpieces 103 (e.g., SiC workpieces). Warpage can be measured by finding the center spot of the workpiece 103 and moving the workpiece 103 under incident light. As the height of the workpiece 103 changes, the center spot will move up and down.

[0047] Figure 2 This is a schematic diagram of another system 120 used to determine the torsion angle 109 and tilt angle 110 of workpiece 103. Figure 2In one embodiment, detector 107 receives the incident light beam 105 reflected from workpiece 103, thus functioning as an imaging device. Detector 107 may be, for example, a camera or a photodiode providing spatial resolution. A camera may sample multiple spatial locations simultaneously. The camera may have associated optics to enable image zoom. A small number of photodiodes may be needed to scan the pattern or detector 107, which may involve twisting and rotating workpiece 103. Signals from the photodiodes can be used to reconstruct the image. In one example, one or more linear arrays of photodiodes may be used as detector 107, and detector 107 may be translated to acquire an image. Detector 107 may also be a sufficiently large array of photodiodes to receive the entire pattern.

[0048] Figure 3 This is a schematic diagram of another system 130 used to determine the torsion angle 109 and tilt angle 110 of workpiece 103. Figure 3 In one embodiment, the chamber has a base 112 (illustrated in...). Figure 3 (Bottom). The stage 102 is configured to hold the workpiece 103 such that the workpiece 103 is perpendicular to the inner surface of the base 112. Therefore, the stage 102 holds the workpiece 103 so that it does not slip off the stage 102 due to gravity. For example, the stage 102 can clamp the workpiece 103 to the stage 102 by electrostatic or physical means. Although the illustration shows a detector 107 with the inner surface 106 of the cavity, Figure 3 System 100 can also be used Figure 2 The detector 107 receives the incident light beam 105 reflected from the workpiece 103. Although the light source 104 is shown facing the inner surface 106 of the cavity along the X-axis, the light source 104 may also face the inner surface 106 of the cavity along the Y-axis (i.e., perpendicular to the page direction).

[0049] remove Figures 1 to 3 In addition to the arrangement shown, it is also possible for the workpiece 103 to be arranged at other angles on the stage 102.

[0050] In the embodiments disclosed herein, processor 111 may also be configured to analyze the speckle pattern of diffraction pattern 108. This can be used to determine surface measurements of workpiece 103. This can provide information to supplement information about the torsion and tilt of workpiece 103. The speckle pattern is a random intensity pattern produced by the interference of a set of wavefronts with different phases. These wavefronts superimpose to form a composite wave with random variations in amplitude and intensity. The speckle pattern is not external noise, but rather an inherent fluctuation in diffuse reflection, because scattering is different for each element, and coherent illumination waves are sensitive to small differences in phase changes. The speckle effect is the result of the interference of multiple light waves of the same frequency but different phases and amplitudes, which are superimposed to provide a composite wave with random amplitude and intensity.

[0051] The speckle pattern can carry information about surface deformation on workpiece 103. The speckle pattern is based on the surface of workpiece 103 and can be formed by X-ray diffraction or other techniques. Roughness, porosity, strain, and stress can affect the distribution, size, or shape of the speckle pattern. This distribution, size, or shape can vary between workpieces 103, and even between different parts of the same workpiece 103. For a patterned workpiece 103, wave interference can originate from surface structures (speckles) and diffraction from embedded features (similar to grating structures). Detector 107 can image workpiece 103 to provide the speckle pattern.

[0052] The size of the speckle pattern provides information about surface deformation. The speckle pattern can also be used to measure the periodicity of components on a workpiece. The density and / or size of the speckle pattern provide information about the workpiece surface. For example, parameters such as correlation intensity and correlation length can be used to provide information about surface deformation. In addition to providing information about the surface, the tilt angle can be confirmed using the specular reflection peak if the center of the master spot is being evaluated. When the workpiece is perfectly flat, the reflected center spot will be located at the reference spot, for example, on the chamber wall. Tilt the workpiece toward or away from the incident light to move the reflected spot up and down. The angle can be determined by measuring the distance between the reference spot and the center spot.

[0053] Speckle patterns can be used to determine information about a workpiece surface, such as the long-range order or degree of order, or to determine the amorphization conditions of patterned or unpatterned workpiece surfaces. Processors can also analyze the speckle patterns of diffraction patterns to determine surface measurements of the workpiece. For example, speckle patterns can determine whether a workpiece is amorphous. Workpieces can also be sensitive to films on their surfaces, which can be used to determine whether the workpiece has been improperly processed, or whether it lacks a film, has an extra film, or has an incorrect film on its surface.

[0054] In another embodiment, the speckle pattern can be used to determine the orientation of the workpiece. A halo, which is spectral, can be formed around the light spot reflected from the workpiece and used for speckle analysis. An example is shown in... Figure 6C The light spot and halo are generally elliptical. The degree of ellipticity of the light spot and halo may deviate from the specifications, which can be used to determine the orientation. The specifications provide an ideal elliptical shape corresponding to the correct orientation, which can vary depending on the workpiece material, film, or workpiece design.

[0055] In another embodiment, a non-transitory computer-readable storage medium includes one or more programs for performing steps on one or more computing devices. The diffraction pattern of an incident beam of light reflected from the surface of a workpiece on a stage, the incident beam being guided at an oblique angle to the surface of the workpiece, is received. The twist angle and tilt angle of the workpiece on the stage are then determined based on the diffraction pattern. Other determinations may also be performed, such as results obtained from speckle pattern analysis.

[0056] Figures 6A to 6E , Figure 7 , Figures 8A to 8G and Figures 9A to 9G Test data from various workpiece samples are shown. The workpieces in these examples are semiconductor wafers.

[0057] For example, Figures 6A to 6E Patterned and unpatterned wafers are shown. Figures 6A to 6B Two patterned wafers with scattering patterns are shown. Figures 6C to 6E Two unpatterned wafers with speckle patterns are shown. Figure 6D and Figure 6E The same wafer is used in both cases. The scattered light spots or XY patterns on patterned wafers can be directional, but they can vary with the pattern on the wafer. On bare, unpatterned wafers, scattering does not show additional scattered light spots. Only speckle patterns are visible on bare, unpatterned wafers. On bare, unpatterned wafers, variations in speckle patterns with 0° to 5° twist cannot be visually determined. The speckle pattern also shows that near-surface conditions have a significant impact on bare, unpatterned wafers.

[0058] Figure 6A and Figure 6B The diagram illustrates the scattering pattern produced by red laser diffraction on a patterned wafer. In addition to the main laser spot, labeled 250, additional circular, vertical, and / or horizontal linear scattering patterns and speckle patterns are visible around the main laser spot, shown as dots in the figure. These circular, vertical, and / or horizontal linear scattering patterns are generated by ordered printed surfaces and / or subsurface structures on the wafer. The scattering pattern will vary for different patterned wafers because the printed surfaces or subsurface structures of different wafers are different.

[0059] Figures 6C to 6E The image shows a speckle pattern produced by red laser diffraction on an unpatterned bare wafer. In this example, a master laser spot and the surrounding speckle are visible in the image. Because no pattern is printed on the surface or subsurface of the wafer, no diffraction-type circular, vertical, and / or horizontal linear scattering patterns are formed. The speckle patterns of the same sample at 0° and 5° twist angles are compared. Figures 6D to 6ENo difference was shown in the speckle pattern. Figures 6D to 6E Compared to the wafers in the middle, Figure 6C The speckle pattern on the medium wafer is wider because compared to Figures 6D to 6E Unpatterned wafers in the middle, Figure 6C The surface and near-surface structure of non-patterned wafers is rougher, and / or has a more damaged crystal structure.

[0060] Figure 7 This illustrates how the shape and size of the scattering profile vary between locations on the wafer. On a patterned wafer, the scattered spots or line patterns are directional. For different locations on the same patterned wafer ( Figure 7 The scattering patterns are obtained at positions 1-5. Locations with specific surface and / or subsurface printed structures will produce specific, representative circular and / or linear scattering patterns. Circular and linear scattering patterns can be produced simultaneously by changing the position of the laser spot, or by using laser spots of different sizes covering different areas of the XY printed features on the surface or subsurface. These scattering patterns can be fitted using circular and curve fitting techniques. In this example, the scattering pattern changes with local features at the focal region. The scattering profile shows a slight to moderate shift / variation detectable from the center outwards. The variation in speckle is not perceptible to the naked eye.

[0061] Figures 8A to 8F The relationship between the torsion angle and the best-fit circle offset, as well as the relationship between the XX and YY tilt angles and the spot offset, is shown for a 30° incident beam.

[0062] Figures 8A to 8C The best-fit circle and fit line are shown for the scattering pattern obtained at a 30° red laser incident angle for a patterned wafer. Figure 8A The scattering pattern and best fit shown are for 0° wafer twist. Figure 8B and Figure 8C These correspond to wafers twisted from the original 0° to -4° and 4°, respectively. For example... Figures 8A to 8C As shown, a shift in the center of the circle was observed for both the -4° and 4° torsion cases.

[0063] Figure 8D The best-fit circles and lines are shown for all wafer torsion angles from -4° to 4°. Dashed arrows indicate the center offset in degrees, and solid arrows indicate the best-fit line offset in mm for various wafer torsion angles. Figure 8E A graph showing the best-fit center and the offset of the fitted line as a function of the wafer twist angle is presented. This graph demonstrates a good systematic countable center offset in degrees and mm, which quantitatively correlates with the wafer twist in any direction.

[0064] Figure 8F The best-fit circle and line are shown for the scattering pattern obtained at a 30° red laser incident angle for a patterned wafer. The intersection of the solid arrows indicates the position of the main laser spot. The arrow direction indicates when the laser beam is tilted (at...). Figure 8F (The middle is horizontal) and / or YY is tilted (in) Figure 8F When the center is vertical, the possible direction of the main laser spot offset.

[0065] Figure 8G The offsets of the master laser spot (in mm) for XX and YY tilts ranging from +2° to -2° are plotted. The figure shows that a well-systematized, countable offset in mm can be quantitatively correlated with wafer tilt along the XX direction (left-right direction from the wafer center) and the YY direction (front-back direction from the wafer center relative to laser incidence).

[0066] Figures 9A to 9F The relationship between the torsion angle and the best-fit circle offset, as well as the relationship between the XX and YY tilt angles and the spot offset, are shown for a 45° incident beam.

[0067] Figures 9A to 9C The best-fit circle and fit line are shown for the scattering pattern obtained at a 45° red laser incident angle for a patterned wafer. Figure 9A The scattering pattern shown and the best fit correspond to a 0° wafer twist. Figure 9B and Figure 9C These correspond to wafers twisted from the original 0° to -4° and 4°, respectively. A shift in the center of the wafer was observed in both the -4° and 4° twist cases.

[0068] Figure 9D This shows the best-fit circles and lines for all wafer torsion angles from -4° to 4°. Dashed arrows indicate the center offset in degrees, and solid arrows indicate the best-fit line offset in mm for various wafer torsion angles. Figure 9E A graph showing the best-fit center and the offset of the fitted line as a function of the wafer twist angle is presented. This graph demonstrates a good systematic countable center offset in degrees and mm, which quantitatively correlates with the wafer twist in any direction.

[0069] Figure 9F The best-fit circle and fitted line are shown for the scattering pattern obtained at a 45° red laser incident angle for a patterned wafer. The intersection of the solid arrows indicates the position of the main laser spot, and the arrow direction indicates when XX tilt occurs (in...). Figure 9F (The middle is horizontal) and / or YY is tilted (in) Figure 9F When the center is vertical, the possible direction of the main laser spot offset.

[0070] Figure 9G The offset of the master laser spot (in mm) for XX and YY tilts ranging from +2° to -2° is plotted. The figure shows that a well-systematized, countable offset in mm can be quantitatively correlated with wafer tilt along the XX direction (left-right direction from the wafer center) and the YY direction (front-back direction from the wafer center relative to laser incidence).

[0071] Figure 10 An exemplary vacuum system 300 is shown, which can implement various apparatuses, systems, and methods of the present disclosure. Vacuum system 300 includes an ion implantation system 301, but the present disclosure also contemplates various other types of vacuum systems, such as plasma processing systems or other semiconductor processing systems. For example, ion implantation system 301 includes a terminal 302, a beam assembly 304, and a terminal station 306.

[0072] Generally, an ion source 308 in terminal 302 is coupled to a power source 310, whereby a gas (also called a dopant gas) supplied to the ion source from a gas source 312 or material from a target is ionized into multiple ions to form an ion beam 314. The ion beam 314 is guided through a beam deflector 316 and directed towards a guide aperture 318 in terminal station 306. In terminal station 306, the ion beam 314 bombards a workpiece 320 (e.g., a semiconductor, such as a silicon wafer, SiC wafer, display panel, etc.), which is selectively clamped or mounted to a stage 322 (e.g., an electrostatic chuck). Once embedded in the lattice of workpiece 320, the implanted ions alter the physical and / or chemical properties of workpiece 320. Therefore, ion implantation is used in semiconductor device fabrication and metal finishing, as well as in various applications in materials science research.

[0073] The ion beam 314 of this disclosure may take any form, such as a pencil beam or dot beam, a strip beam, a scanning beam, or any other form that guides ions toward the terminal station 306, all of which are considered to fall within the scope of this disclosure.

[0074] Terminal station 306 includes a processing chamber 324, such as a vacuum chamber 326, wherein a processing environment 328 is associated with the processing chamber. For example, the processing environment 328 within the processing chamber 324 includes a vacuum generated by a vacuum source 330 (e.g., a vacuum pump), which is coupled to the processing chamber 324 and configured to substantially evacuate the processing chamber 324. A controller 332 is provided for overall control of the vacuum system 300. The controller 332 may include a processor 111, or may be detachable from the processor 111.

[0075] For example, ion source 308 (also known as ion source chamber) can be constructed from refractory metals (tungsten, molybdenum, tantalum, etc.) and graphite to provide suitable high-temperature performance; such materials are commonly accepted by semiconductor manufacturers. Gas from gas source 312 is used within ion source 308. The source gas can be conductive or non-conductive in nature.

[0076] Vacuum system 300 may employ any of the embodiments disclosed herein. Therefore, terminal station 306 may include components of system 100 disclosed herein, such as light source 104, detector 107, or chamber inner surface 106. Terminal station 306 may be an example of chamber 101, and stage 322 may be an example of stage 110. Workpiece 320 may be an example of workpiece 103. In one example, the wall of terminal station 306 is chamber inner surface 106.

[0077] Embodiments of this disclosure can also be implemented in various semiconductor processing apparatuses, such as those for chemical vapor deposition (CVD), physical vapor deposition (PVD), metal-organic chemical vapor deposition (MOCVD), chemical-mechanical polishing (CMP), etching, and various other semiconductor processing applications, all of which are considered to fall within the scope of this disclosure.

[0078] Although this disclosure has been described with respect to one or more specific embodiments, it should be understood that other embodiments of this disclosure may be devised without departing from the scope of this disclosure. Therefore, this disclosure is considered to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A system comprising: Chamber; A stage configured to hold a workpiece, wherein the stage is disposed within the cavity; A light source is configured to guide an incident light beam to the surface of a workpiece on the stage, wherein the incident light beam is guided to the surface of the workpiece at an oblique angle. A detector configured to image the diffraction pattern of the incident light beam reflected from the workpiece; and A processor that communicates electronically with the detector, wherein the processor is configured to determine at least one of a torsion angle and a tilt angle of the workpiece on the stage based on the diffraction pattern.

2. The system according to claim 1, wherein, The light source is a laser, and the incident beam is mainly red light.

3. The system according to claim 1, wherein, The incident beam has a diameter ranging from 0.5 mm to 0.7 mm.

4. The system according to claim 1, wherein, The incident light beam is incident on the workpiece at an angle of 30° to 60°.

5. The system according to claim 1, wherein, The detector is a camera.

6. The system according to claim 1, wherein, The stage is an electrostatic chuck.

7. The system according to claim 1, wherein, The chamber has a chamber surface, wherein the incident light beam is reflected from the workpiece onto the chamber surface, and wherein the diffraction pattern is imaged on the chamber surface by the detector.

8. The system according to claim 1, wherein, The detector directly receives the incident light beam reflected from the workpiece.

9. The system according to claim 1, wherein, Determining at least one of the twist angle and the tilt angle includes determining the center offset of the diffraction pattern.

10. The system according to claim 1, wherein, Determining at least one of the twist angle and the tilt angle includes determining the curvature of the diffraction pattern and determining the center of the workpiece.

11. The system according to claim 1, wherein, The processor is further configured to analyze the speckle pattern of the diffraction pattern to determine the surface measurement results of the workpiece.

12. A method comprising: An incident light beam from a light source is directed to a workpiece on a stage within a chamber, wherein the incident light beam is directed at an angle to the surface of the workpiece. The incident light beam is reflected from the surface of the workpiece; Image the diffraction pattern of the incident light beam reflected from the workpiece; as well as Using a processor, at least one of the twist angle and tilt angle of the workpiece on the stage is determined based on the diffraction pattern.

13. The method according to claim 12, wherein, The light source is a laser, and the incident beam is mainly red light.

14. The method according to claim 12, wherein, The incident light beam is incident on the workpiece at an angle of 30° to 60°.

15. The method of claim 12, further comprising: The workpiece on the stage is twisted and / or tilted based on the twist angle and / or the tilt angle.

16. The method according to claim 12, wherein, The workpiece is a patterned semiconductor wafer.

17. The method according to claim 12, wherein, Determining at least one of the twist angle and the tilt angle includes determining the center offset of the diffraction pattern.

18. The method according to claim 12, wherein, Determining at least one of the twist angle and the tilt angle includes determining the curvature of the diffraction pattern and determining the center of the workpiece.

19. The method of claim 12, further comprising: The processor is used to analyze the speckle pattern of the diffraction pattern to determine the surface measurement results of the workpiece.

20. A non-transitory computer-readable storage medium comprising one or more programs for performing the following steps on one or more computing devices: The diffraction pattern of the incident light beam reflected from the surface of the workpiece on the stage is received, wherein, The incident beam is guided at an oblique angle to the surface of the workpiece; as well as Based on the diffraction pattern, at least one of the twist angle and tilt angle of the workpiece on the stage is determined.

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