X-ray refraction angle verification in ion implanter

Abstract

An ion implanter that facilitates directing an ion beam into a crystalline structure of a workpiece is disclosed. The ion implanter comprises: an ion source for generating an ion beam; the bedplate is used for supporting a workpiece with a crystal structure; an X-ray source for generating an X-ray beam wherein at least a portion of the X-ray beam impinges on the workpiece to generate diffracted X-rays; an X-ray detector positioned to receive the diffracted X-rays; and a controller in communication with the X-ray source, the platen, and the X-ray detector. The controller includes instructions to enable the ion implanter to perform a rocking curve test after the workpiece is disposed on the platen; and calculating the orientation of the platen for the ion implantation process based on the results of the rocking curve test to facilitate directing the ion beam into the crystalline structure of the workpiece.

Description

[0001] This application claims priority to U.S. patent application serial number 18 / 091,041, filed on December 29, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] Embodiments of the present disclosure relate to an ion implanter that uses X-ray diffraction (XRD) to perform angular alignment prior to implantation. Background Art

[0003] For many years, silicon has been the primary material used for semiconductor workpieces. Silicon workpieces have been used to form transistors, memory elements, amplifiers, and other devices.

[0004] Recently, more semiconductor devices are being manufactured using alternative workpieces having various crystalline structures, some of which include silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), and other materials.

[0005] In some scenarios, it's desirable to perform the ion implantation process in a manner that directs the ions into channels within the crystalline structure. This requires precise alignment of the ion beam with the crystal lattice. For silicon workpieces, the workpiece orientation is well known. However, other workpieces may differ. For example, silicon carbide has a more complex crystalline structure than silicon. In fact, silicon carbide can form a variety of different polytypes with varying crystalline structures.

[0006] Furthermore, the specifications accompanying SiC workpieces can be difficult to understand, complicating identification of the workpiece's orientation. Due to the conditions under which the crystal was grown, the c-axis of a 4H SiC crystal typically deviates by 4° + / - 1° relative to the normal to the workpiece surface, and the direction of this tilt is not always obvious. The magnitude and direction of the tilt can also vary from workpiece to workpiece and from point to point on the workpiece. Consequently, processing results can differ when the ion beam enters and exits channeling conditions.

[0007] Therefore, it would be beneficial if there were an ion implanter that could determine and monitor the crystallographic orientation of a workpiece prior to an ion implantation process to facilitate directing an ion beam into the workpiece and implanting ions into the workpiece. Summary of the Invention

[0008] According to one embodiment, an ion implanter is disclosed. The ion implanter includes an ion source for generating an ion beam; a platen for supporting a workpiece having a crystalline structure; an X-ray source for generating an X-ray beam, wherein at least a portion of the X-ray beam strikes the workpiece to generate diffracted X-rays; an X-ray detector positioned to receive the diffracted X-rays; and a controller in communication with the X-ray source, the platen, and the X-ray detector. The controller includes a memory device containing instructions that, when executed by the controller, enable the ion implanter to: perform a rocking curve test after the workpiece is positioned on the platen; and calculate an orientation of the platen for an ion implantation process based on the results of the rocking curve test to facilitate directing the ion beam into the crystalline structure of the workpiece. In some embodiments, the memory device further contains instructions that, when executed by the controller, enable the ion implanter to: perform an ion implantation process while the workpiece is positioned on the platen in the calculated orientation. In some embodiments, the rocking curve test is performed while the platen is positioned in a loading position, wherein the clamping surface of the platen is horizontal in the loading position. In some embodiments, the rocking curve test is performed at multiple locations on the workpiece. In some embodiments, the workpiece is rotated about an axis passing through the center of the platen and perpendicular to the clamping surface of the platen such that the X-ray beam strikes a new location on the workpiece. In some embodiments, the ion beam has a width in the X-direction and a height in the Y-direction, and the platen is translated in the Y-direction such that the X-ray beam strikes a new location on the workpiece. In some embodiments, the platen is adapted to tilt about an X-axis and a Y-axis, wherein the X-axis passes through the center of the platen and is parallel to the width of the ion beam, and the Y-axis passes through the center of the platen and is parallel to the height of the ion beam, and wherein a rocking curve test is performed when the platen is tilted about the X-axis to determine an X-tilt angle having a maximum intensity, and when the platen is tilted about the Y-axis to determine a Y-tilt angle having a maximum intensity, and wherein the controller calculates an orientation to be used for the ion implantation process based on the X-tilt angle and the Y-tilt angle determined during the rocking curve test. In certain embodiments, the X-ray detector is a two-dimensional sensor array such that the estimated X-tilt angle and the estimated Y-tilt angle are determined without tilting the workpiece, and the rocking curve test is performed by tilting about the estimated X-tilt angle and the estimated Y-tilt angle. In some embodiments, the ion implanter includes a collimator positioned to receive the X-ray beam from the X-ray source and collimate the X-ray beam to provide the portion of the X-ray beam to the workpiece.In some embodiments, the platen, the X-ray source, and the X-ray detector are disposed in a processing chamber configured to receive the ion beam. In certain embodiments, the X-ray source and the X-ray detector are disposed on a top portion of the processing chamber. In some embodiments, the platen is disposed in the processing chamber configured to receive the ion beam, and at least one of the X-ray source and the X-ray detector is disposed outside the processing chamber, and a window is disposed in the processing chamber to allow X-rays to pass between the processing chamber and an environment outside the processing chamber. In some embodiments, the X-ray source and the X-ray detector are movable to adjust the angle at which the X-ray beam strikes the workpiece.

[0009] According to another embodiment, an ion implanter is disclosed. The ion implanter includes: an ion source for generating an ion beam; a processing chamber, wherein the ion beam enters the processing chamber and a platen is disposed in the processing chamber; an auxiliary chamber disposed adjacent to the processing chamber, the auxiliary chamber comprising: an auxiliary platen adapted to support a workpiece having a crystalline structure; an X-ray source for generating an X-ray beam, wherein at least a portion of the X-ray beam strikes the workpiece to generate diffracted X-rays; an X-ray detector positioned to receive the diffracted X-rays; a workpiece handling robot for transferring the workpiece from the auxiliary chamber to the processing chamber; and a controller coupled to the X-ray source. The ion implanter is configured to communicate with the auxiliary platen, the auxiliary platen, the X-ray detector, the platen, and the workpiece handling robot, wherein the controller includes a memory device containing instructions that, when executed by the controller, enable the ion implanter to: perform a rocking curve test after the workpiece is positioned on the auxiliary platen; calculate an orientation of the workpiece for an ion implantation process based on the results of the rocking curve test to facilitate directing the ion beam into the crystal structure of the workpiece; and transfer the workpiece to the platen in the processing chamber using the workpiece handling robot. In some embodiments, the ion implanter includes a second X-ray source and a second X-ray detector, wherein the memory device further contains instructions that, when executed by the controller, enable the ion implanter to: perform a second rocking curve test in the processing chamber using the second X-ray source and the second X-ray detector after the workpiece has been transferred to the processing chamber. In some embodiments, the second X-ray source and the second X-ray detector are positioned within the processing chamber. In some embodiments, the platen includes a heater, and the memory device further includes instructions that, when executed by the controller, enable the ion implanter to: heat the platen after the workpiece is transferred to the processing chamber; and perform a second rocking curve test in the processing chamber using the second X-ray source and the second X-ray detector after the workpiece has reached a desired temperature. In some embodiments, the second X-ray source and the second X-ray detector are positioned in the processing chamber. In some embodiments, the X-ray detector includes a two-dimensional sensor array, such that an estimated X tilt angle and an estimated Y tilt angle are determined during the rocking curve test, and wherein the second rocking curve test is performed in the processing chamber by tilting the platen about the estimated X tilt angle and the estimated Y tilt angle. In some embodiments, the memory device further includes instructions that, when executed by the controller, enable the ion implanter to: perform an ion implantation process while the workpiece is positioned on the platen in the calculated orientation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a better understanding of the present disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference, and wherein:

[0011] Figure 1 An ion implanter according to one embodiment is shown.

[0012] Figure 2A FIG. 4 shows one configuration of an X-ray source and an X-ray detector in a processing chamber.

[0013] Figure 2B Another arrangement of an X-ray source and an X-ray detector in a processing chamber is shown.

[0014] Figure 2C A third configuration of an X-ray source and an X-ray detector in a processing chamber is shown.

[0015] Figure 2D The arrangement of the X-ray source and the X-ray detector outside the processing chamber is shown.

[0016] Figure 3 Shows the rotation and tilt of the workpiece on the platen.

[0017] Figure 4 An X-ray source and a collimator according to one embodiment are shown.

[0018] Figure 5 Shown available for use Figure 1 An ion implanter is shown performing a sequence of processing on a workpiece.

[0019] Figure 6 Shows that you can use Figure 1 One embodiment of a rocking curve test performed on an ion implanter is shown.

[0020] Figure 7 An ion implanter according to another embodiment is shown.

[0021] Figure 8 Shown available for use Figure 7 An ion implanter is shown performing a sequence of processing on a workpiece. DETAILED DESCRIPTION

[0022] As mentioned previously, in some cases it may be beneficial to perform a channeled implant. The term "channeled implant" refers to an implant performed so that ions are implanted along a channel in the crystalline structure of a workpiece (e.g., a SiC wafer). However, it can be difficult to correctly orient the workpiece so that the incoming ion beam is aligned with the channel. The accuracy of this alignment depends on several parameters, but most notably on the energy of the ions, with efficient channeling using a maximum angular deviation that decreases with increasing energy. The critical angle for channeling is given by the equation

[0023]

[0024] Where ψ is the critical angle, U(r crit ) is the potential energy of the channel wall determined by the lattice, and E is the kinetic energy of the ion. For high-energy implants of several million electron volts, the angular acceptance of the channel can be as small as 0.05°, and can be several degrees at several kiloelectron volts.

[0025] Figure 1 A first embodiment of an ion implanter 1 is shown that is capable of performing angular alignment and verification using XRD before performing the implant.

[0026] In some embodiments, the ion implanter 1 can be a high energy ion implanter or a medium current beamline ion implanter capable of producing an implantation energy of 1 million electron volts or greater. In other embodiments, the implantation energy produced by the ion implanter 1 can be less than 1 million electron volts. The ion implanter 1 includes an ion source 200 for producing an extracted ion beam 201. In one embodiment, the ion source 200 can be a Bernas ion source or an indirectly heated cathode (IHC) ion source. Of course, other types of ion sources can also be used. A feed gas is supplied to the ion source 200, which is then charged to produce ions. The ions are then extracted from the ion source 200 using extraction optics (not shown) and formed into the extracted ion beam 201.

[0027] The extracted ion beam 201 can be directed toward a mass analyzer 205, which allows only certain types of ions to pass through. The ions exiting the mass analyzer 205 are directed toward an accelerator assembly 210. The accelerator assembly 210 is used to accelerate the ions entering the assembly from lower energy to higher energy. The accelerator assembly 210 can have different configurations.

[0028] In one embodiment, the accelerator assembly 210 may be an acceleration column comprising a plurality of biased electrodes for accelerating the ion beam. As the ions pass through the column, the electrodes may be biased more negatively, thereby accelerating the positive ions.

[0029] In another embodiment, the accelerator assembly 210 may be a tandem accelerator. In this embodiment, negative ions may be admitted into a first accelerator column and accelerated to a first energy, and then electrons of the negative ions are stripped away to form positive ions that are accelerated by a second accelerator column to a final higher energy.

[0030] In another embodiment, the accelerator assembly 210 may be a linear accelerator (LINAC). In this embodiment, a separate buncher may receive the ion beam from the ion source 200 and produce a bunched pulsed ion beam. A series of resonators or accelerators may be excited by respective radio frequency (RF) signals to increase the velocity of the incoming pulsed beam to a desired high energy level.

[0031] In all of these embodiments, after exiting the accelerator assembly 210, the point ion beam 211 may enter a scanner 215. The scanner 215 causes the point ion beam 211 to spread out into a plurality of diverging ion beamlets. In other words, the scanner 215 forms a diverging ion trajectory path. The scanner 215 may be electrostatic or magnetic. By using the scanner 215, the ion beam becomes wider. The direction in which the scanner 215 moves the beam may be referred to as the X direction. It should be noted that after exiting the scanner 215, the ion beam is wider than its height.

[0032] Angle corrector 220 is designed to deflect ions in the scanned ion beam to generate an ion beam 230 having parallel ion trajectories, thereby focusing the scanned ion beam. Specifically, angle corrector 220 is used to change the diverging ion trajectory paths to substantially parallel paths for ion beam 230. In some embodiments, angle corrector 220 may include magnetic pole pieces spaced apart to define a gap and a magnet coil coupled to a power supply. The scanned ion beam passes through the gap between the pole pieces and is deflected according to the magnetic field in the gap. In other embodiments, angle corrector 220 may be an electrostatic lens, sometimes referred to as a parallelizing lens.

[0033] Of course, the ion implanter may include other components, such as a quadrupole lens, additional electrodes for accelerating or decelerating the ion beam, and other elements.

[0034] The ion beam 230 enters the processing chamber 100. Figure 1 1 shows a top view of the ion implanter 1 such that the height of the ion beam 230 is perpendicular to the plane of the drawing. A Cartesian coordinate system can be defined to aid in the explanation, where the Z direction is defined by the path of the ion beam 230. Figure 1 As shown in FIG, ion beam 230 has a height in the Y direction and a width in the X direction.

[0035] like Figure 1 As shown in FIG, ion beam 230 enters processing chamber 100, in which a workpiece to be implanted is disposed. Workpiece 10 is disposed on a clamping surface 169 of platen 160. Platen 160 may be capable of movement and rotation in several directions. Figure 1 , platen 160 is in an operating or implantation position, wherein the clamping surface 169 of the platen 160 is substantially perpendicular to the ion beam 230. This is the orientation of the platen 160 during ion implantation. In this embodiment, the X-ray source 110 and the X-ray detector 130 are disposed on either side of the platen 160 in the X-direction or width direction.

[0036] exist Figure 2A , a perspective view of the processing chamber 100 is shown, wherein the X-ray source 110 and the X-ray detector 130 are positioned in the processing chamber 100 and disposed on either side of the platen 160 in the X direction.

[0037] However, other embodiments are possible. Figure 2B A perspective view of a processing chamber 100 according to another embodiment is shown. In this embodiment, an X-ray source 110 and an X-ray detector 130 are positioned in the processing chamber 100 and disposed on either side of a platen 160 in the Y direction or height direction.

[0038] The workpiece 10 can be moved in one or more dimensions by the stage 160. For example, the stage 160 can be moved in the Y direction (corresponding to the height of the ion beam 230) so that after the stage 160 has moved through the ion beam 230, the entire workpiece 10 is exposed to the ion beam 230. The stage 160 can also be tilted and rotated about several axes.

[0039] Figure 3 The platen 160 and various rotational orientations of the platen 160 are shown. Figure 3A perspective view of a platen 160 capable of rotation and referred to as a roplat is shown. Platen 160 may have three axes. There may be a torsion axis 161, which is perpendicular to a clamping surface 169 of platen 160 and passes through the center of platen 160. Rotation about this torsion axis 161 is referred to as a torsion angle 162. There is an X-axis 163, which passes through the center of the platen, is parallel to the clamping surface 169 of platen 160, and is perpendicular to torsion axis 161. X-axis 163 is parallel to the wide dimension of ion beam 230. Tilting about X-axis 163 is referred to as an X-tilt angle 164. There is also a Y-axis 165, which also passes through the center of platen 160, is parallel to the clamping surface 169 of platen 160, and is perpendicular to torsion axis 161 and X-axis 163. Tilting about Y-axis 165 is referred to as a Y-tilt angle 166.

[0040] The X-ray source 110 and the X-ray detector 130 are also disposed in the processing chamber 100. Figure 4 As shown in , a collimator 115 may also be used to receive the X-ray beam from the X-ray source 110 to provide collimation of the X-rays and form an emitted X-ray beam 120. In some embodiments, the X-ray source 110 may be a filtered Cu target X-ray source or any other suitable X-ray source known in the art. The collimator 115 may be used to generate a tightly parallel beam that can be directed toward a specific area of the workpiece 10. In some embodiments, the collimator 115 includes one or more slits. In other embodiments, the collimator 115 includes one or more crystals, such as a germanium crystal or a silicon crystal. In one embodiment, as Figure 4As shown in , the X-ray beam from the X-ray source 110 enters the germanium crystal 118 through one face and is reflected off the two inner faces in the (220) direction before exiting the crystal as the emitted X-ray beam 120. This may be referred to as a Ge(220)-2 bounce collimator or monochromator. In another embodiment, the two crystals are arranged so that when the X-ray leaves the first germanium crystal, it enters the second germanium crystal and is reflected off the two inner faces again in the (220) direction before exiting as the emitted X-ray beam 120. This may be referred to as a Ge(220)-4 bounce collimator or monochromator. In another embodiment, the crystals may be arranged so that the X-ray beam from the X-ray source 110 enters one face and is reflected off the two inner faces in the (440) direction. The X-ray then leaves the first germanium crystal and enters the second germanium crystal, where it is reflected off the two inner faces again in the (440) direction before exiting as the emitted X-ray beam 120. This may be referred to as a Ge(440)-4 bounce collimator or monochromator. Of course, other collimators may also be used. When a crystal is used, only the X-ray beam having the desired trajectory can pass through the crystal and reach the workpiece 10. In each of these embodiments, the X-ray source 110 generates an X-ray beam, at least a portion of which ultimately strikes the workpiece 10 as the emitted X-ray beam 120.

[0041] The X-ray detector 130 measures the diffracted X-rays 125 from the workpiece and can be used to plot the amount of diffracted X-rays 125 detected (also known as intensity) as a function of the X tilt angle and the Y tilt angle, as shown in FIG. Figure 1 The X-ray detector 130 is well known and will not be described in detail herein. In some embodiments, the X-ray source 110, the workpiece 10, and the X-ray detector 130 are arranged to achieve a Bragg scattering angle given by the Bragg equation:

[0042] λ=2dsinθ

[0043] where λ is the wavelength of the X-ray (for Cu K α ray is 0.1541 nm), d is the spacing between crystal planes; in the given In this case, for 4HSiC in the (0001) direction, the selection rule is such that the (0004) plane can give a spacing of c / 4 = 0.251 nm.

[0044] For different wavelengths of X-ray beams or workpieces of different materials, the X-ray source 110 and the X-ray detector 130 can be positioned at different angles.

[0045] In another embodiment, the X-ray source and the X-ray detector are mounted on an articulated arm so that the X-ray source and the X-ray detector can be used for different diffraction angles at different lattice spacings.

[0046] In another embodiment, X-ray detector 130 may be a one-dimensional or two-dimensional sensor array, which can be used to enable detection of a range of X-ray diffraction angles. In these embodiments, X-ray detector 130 includes multiple sensors, each of which is adapted to detect X-rays. Such a one-dimensional or two-dimensional X-ray detector may be referred to as an extended X-ray detector. In this manner, such an extended X-ray detector can simultaneously provide information regarding multiple angles, rather than only receiving information regarding a single angle.

[0047] The ion implanter 1 is also controlled using a controller 280. The controller 280 includes a processing unit 281 and an associated memory device 282. The memory device 282 contains instructions 283 that, when executed by the processing unit 281, enable the system to perform the functions described herein. The controller 280 controls the twist angle 162, the X-tilt angle 164, and the Y-tilt angle 166 of the platen 160. The controller 280 also communicates with components of the ion implanter 1, including the X-ray source 110 and the X-ray detector 130. The memory device 282 can be any non-transitory storage medium, including non-volatile memory such as flash read-only memory (ROM), electrically erasable ROM, or other suitable devices. In other embodiments, the memory device 282 can be volatile memory such as random access memory (RAM) or dynamic random access memory (DRAM). In some embodiments, the controller 280 may be a general purpose computer, an embedded processor, or a specially designed microcontroller. The actual implementation of the controller 280 is not limited by the present disclosure.

[0048] Having described one configuration of the ion implanter 1 , the operation of the system will be described.

[0049] exist Figure 5 One mode of operation is shown in FIG. Figure 5As shown in block 500 of FIG. 1 , a workpiece 10 is positioned on the clamping surface 169 of the platen 160 in the processing chamber 100. The platen 160 is positioned in its operating position. The controller 280 may then use the X-ray source 110, the X-ray detector 130, and the platen 160 to perform a rocking curve test, as shown in block 510. Rocking curve testing is known to be used in conjunction with XRD to identify the orientation of the crystalline structure of a workpiece. Specifically, a rocking curve test causes the angle of the workpiece to vary while the X-ray beam strikes the workpiece. The X-rays are diffracted and received by the X-ray detector. The angle of the workpiece that produces the maximum intensity of the diffracted X-rays is the maximum steering direction. The rocking curve test can be performed in one or both directions, for example, by tilting the workpiece about the X-axis 163 and / or by tilting the workpiece about the Y-axis 165.

[0050] The controller 280 can then store the X and Y tilt angles that resulted in the peak intensity, as shown in block 520. Based on this information, the controller 280 can determine the crystallographic orientation of the workpiece 10 and, therefore, the correct orientation of the workpiece 10 during subsequent implantation, as shown in block 530. For example, SiC is available in a variety of different polytypes, including 2H, 4H, 6H, 15R, and 3C. Each polytype can utilize a different set of optimal tilt angles. By performing a rocking curve test, the controller 280 can identify the polytype and also the correct orientation of the workpiece. Once the X and Y tilt angles are calculated, these calculated angles can be used during the ion implantation process, as shown in block 540.

[0051] exist Figure 2A In the embodiment shown in , when the ion beam 230 is precisely in the Z direction and the X-ray source 110 and X-ray detector 130 are angularly symmetric about the Z direction, the optimal guidance will be at the workpiece angle that maximizes the X-ray diffraction intensity. Several possible events may cause this simple algorithm to change. For example, if accurate measurements of the ion beam 230 show that it is slightly angled relative to the Z axis, or if the X-ray source 110 or X-ray detector 130 are offset from their ideal positions due to mechanical tolerances, these shifts need to be accounted for by offsetting the implantation angle relative to the angle of maximum diffraction intensity.

[0052] By determining the X- and Y-tilt angles that maximize the intensity of the X-ray emission, controller 280 can identify the appropriate orientation of platen 160 to be used for the implant process, facilitating guidance. Specifically, in some embodiments, it may be desirable to perform an implant with the workpiece oriented on platen 160 so that the implant is guided. This allows the implanted ions to be implanted deeper (for a given energy) and also causes less damage to the workpiece. In some embodiments, the X- and Y-tilt angles are selected to maximize guidance.

[0053] Figure 6 A sequence that can be used to perform a rocking curve test is shown. First, as shown in box 600, the X-ray source 110 and the X-ray detector 130 are enabled. The controller 280 then varies the X-tilt angle 164 of the platen 160 while directing the emitted X-ray beam 120 at the workpiece 10, as shown in box 610. The X-tilt angle range used during the rocking curve test can be varied. For example, in some embodiments, the workpiece can be tilted by ±5°. In other embodiments, the angle range can be smaller, such as ±1° or ±2°. In yet other embodiments, the angle range can be greater than 5°. The intensity of the diffracted X-rays 125 is recorded using the X-ray detector 130, and the controller 280 saves the recorded intensities as a function of the X-tilt angle, as shown in box 620. The result of such a process can be Figure 1 The graph 135 shown in may be a table of values. The controller 280 then varies the Y tilt angle 166 of the platen 160 while directing the emitted X-ray beam 120 at the workpiece 10, as shown in block 630. In some embodiments, the X tilt angle is set to the X tilt angle that exhibits the maximum intensity. Also, as described above, the range of Y tilt angles used during the rocking curve test may vary. The intensity of the diffracted X-rays 125 is recorded using the X-ray detector 130, and the controller 280 saves the recorded intensities as a function of the Y tilt angle, as shown in block 640. The result of such a process may be Figure 1 Alternatively, the second graph 135 shown in FIG. 1 may be one or more tables, each including tilt angle values and corresponding intensity values. Once this is complete, the controller 280 may deactivate the X-ray source 110 and the X-ray detector 130. Note that in some embodiments, the rocking curve test is performed for only one tilt angle. For example, in some embodiments, blocks 610-620 or blocks 630-640 may be omitted.

[0054] In yet other embodiments, if an extended X-ray detector is used, the variations in the X and Y tilt angles may be smaller. For example, a two-dimensional X-ray detector may enable controller 280 to determine the X and Y tilt angles that exhibit the highest intensity without rotating the workpiece. In another embodiment using an extended X-ray detector, the initial output from the extended X-ray detector is used to set estimated X and Y tilt angles, and a rocking curve test is then performed, tilting the platen around these estimated angles. For example, an initial scan may indicate that the maximum intensity is detected at tilt angles X1 and Y1. A rocking curve test may then be performed using, for example, X1±1° for X and Y1±1° for Y, respectively.

[0055] In some embodiments, it may be beneficial to perform rocking curve testing at multiple locations on the workpiece. This may be accomplished in a variety of ways. In one embodiment, the platen 160 may be moved in the Y direction so that the emitted X-ray beam 120 can strike different locations on the workpiece. In another embodiment, the platen 160 may be rotated about the torsion axis 161 so that the emitted X-ray beam 120 can strike different locations on the workpiece. In another embodiment, the platen 160 may be moved in the Y direction and rotated about the torsion axis 161. In each of these embodiments, once the workpiece 10 has been moved or rotated, the rocking curve test may be repeated. Figure 6 . In some embodiments, the results from the multiple rocking curve tests may be averaged to determine appropriate X-tilt and Y-tilt angles for the implant process. In other embodiments, the X-tilt and Y-tilt angles may vary as a function of the position of the platen 160 in the Y direction. For example, if the X-tilt and / or Y-tilt angles vary along the Y direction, the tilt of the platen 160 may vary as the ion beam 230 scans the workpiece 10. If the X-tilt and / or Y-tilt angles vary along the X-axis, the angle corrector 220 may be adjusted to generate a converging or diverging ion beam to account for the Y-tilt variation, while the rotation of the scanning plate may be adjusted to generate a twist in the trajectory to account for the X-tilt variation.

[0056] In some embodiments, the platen 160 may also heat the workpiece 10 to an elevated temperature, such as greater than 350° C. In some embodiments, the elevated temperature may be 500° C. or greater. In these embodiments, the rocking curve test may not be performed until the workpiece 10 reaches the desired temperature.

[0057] In other embodiments, the rocking curve test can be performed before the workpiece is heated and then again after the workpiece is heated. In this way, any changes in the rocking curve test results may be the result of thermal warping or deformation of the workpiece. This can be compensated for by applying additional clamping force (electrostatic or mechanical). Alternatively, the orientation of the platen 160 can be adjusted to achieve the best compromise in workpiece shape at the implant temperature.

[0058] although Figure 1 and Figures 2A to 2B The rocking curve test is shown being performed while the platen 160 is in an operating position, however other embodiments are possible. Figure 2C A perspective view of the processing chamber 100 is shown. In this embodiment, the platen 160 is disposed in a loading position, wherein the clamping surface of the platen 160 is horizontal. In this embodiment, the X-ray source 110 and the X-ray detector 130 are disposed inside the processing chamber 100 and are disposed near the top portion of the processing chamber 100. The area near the top portion of the processing chamber 100 may have fewer contaminants than other areas. In this embodiment, the X tilt angle is set to 90° to place the platen 160 in the loading position. The X tilt angle is then varied around this tilt angle. In other words, although Figure 1 and Figures 2A to 2B The embodiment shown varies the X tilt angle by approximately 0°, however Figure 2C The embodiment shown varies the X tilt angle by approximately 90°.

[0059] In another embodiment, at least one of the X-ray source 110 or the X-ray detector 130 may be disposed outside the processing chamber 100. Figure 2D As shown in . For example, a window may be provided in the wall of the processing chamber 100 so that X-rays can pass through the window. In one embodiment, both the X-ray source 110 and the X-ray detector 130 are provided outside the processing chamber 100. In this embodiment, the X-rays leaving the X-ray source 110 pass through the first window and enter the processing chamber 100, where the X-rays hit the workpiece 10. The diffracted X-rays then pass through the second window to the X-ray detector 130. In some embodiments, the window may be a thin polymer film, a diamond-like carbon window, or a beryllium window. The X-ray source 110 and / or the X-ray detector 130 may be as shown in . Figure 2D 1 and 2, or may be positioned above the top surface of the processing chamber 100.

[0060] In some embodiments, rocking curve testing may be performed in a chamber separate from the processing chamber. Figure 7One such embodiment is shown in . The ion implanter 1 may include an ion source 200, a mass analyzer 205, an accelerator assembly 210, a scanner 215, and an angle corrector 220, although these are not shown.

[0061] In this embodiment, the X-ray source 110 and the X-ray detector 130 are disposed in an auxiliary chamber 300. An auxiliary table 310 is also disposed in the auxiliary chamber 300. The auxiliary table 310 may be similar to the table 160 described above in that it can rotate about one or more axes.

[0062] In this way, the rocking curve test can be performed in the auxiliary chamber 300. Since the rocking curve test is not performed using the processing chamber 100, this can enable a higher throughput. Therefore, in this embodiment, the rocking curve test is performed in the auxiliary chamber 300, and the workpiece is moved to the processing chamber 100 using the workpiece transfer robot 320. The rocking curve test can be performed while the clamping surface of the auxiliary platen 310 is vertical, such as Figure 7 In other embodiments, Figure 2C Similar to the embodiment shown in , the rocking curve test can be performed while the clamping surface of the auxiliary platen 310 is horizontal. Figure 8 A sequence is shown in FIG. 1 , which shows the operations associated with this embodiment.

[0063] As shown in block 800, the workpiece is placed on the clamping surface of the auxiliary platen 310 in the auxiliary chamber 300. Identification of the workpiece is performed. In block 810, the controller 280 then performs a rocking curve test, such as for Figure 6 As described. As shown in box 820, the controller 280 stores the X tilt angle and Y tilt angle at which the detected intensity is at a peak. As shown in box 830, these tilt angles can then be used to calculate the orientation to be used during a subsequent ion implantation process. As shown in box 840, the controller 280 then stores the identity of the workpiece and the orientation associated with the workpiece. As shown in box 850, the controller 280 then uses the workpiece handling robot 320 to move the workpiece to the processing chamber 100 while maintaining the orientation of the workpiece. As shown in box 860, once in the processing chamber 100, the controller 280 identifies the workpiece and then performs the ion implantation process using the calculated orientation associated with the workpiece (i.e., the X tilt angle and the Y tilt angle). This approach minimizes the time the workpiece resides in the processing chamber 100, which in turn increases throughput.

[0064] In some embodiments, the controller may store the X tilt angle and the Y tilt angle from block 830 and not calculate the orientation to be used for the implant process until later.

[0065] In yet another embodiment, the X-ray source 110 and the X-ray detector 130 may be replicated, such that the X-ray source 110 is present in both the auxiliary chamber 300 and the processing chamber 100. Similarly, the X-ray detector 130 may be present in both the auxiliary chamber 300 and the processing chamber 100. In this embodiment, a rocking curve test may be performed in the auxiliary chamber 300. After the workpiece is moved to the processing chamber 100, the workpiece may be heated. This temperature change may affect the orientation used for the ion implantation process. Therefore, after heating, a second rocking curve test may be repeated. However, since the preliminary rocking curve test has already been performed in the auxiliary chamber 300, the angular range used in the second rocking curve test may be smaller, thereby enabling the test to be completed more quickly.

[0066] In one embodiment, an extended X-ray detector may be disposed in the auxiliary chamber 300 and may determine estimated X and Y tilt angles without tilting the workpiece. These estimated X and Y tilt angles are then used as the center of a rocking curve test performed in the processing chamber 100.

[0067] While the above disclosure refers to SiC workpieces, it should be understood that the system is not limited to silicon carbide. In one embodiment, if the geometry of the workpiece is known, the X-ray source 110 and X-ray detector 130 can be moved to the appropriate angles to satisfy the Bragg equation. Movement of the components can be performed manually or controlled by the controller 280.

[0068] In another embodiment, the system can be used on workpieces of various geometries. Figure 4 The collimator 115 shown in FIG. 1 may not be used to enable the emitted X-ray beam 120 to have a much wider angular range. In this embodiment, the X-ray source 110 can generate a broad spectrum of energies or wavelengths, such that the Bragg equation is satisfied for a wide range of lattice spacings and scattering angles. This can be achieved by using a tungsten target and sufficiently high electron energies to generate braking radiation rather than characteristic X-ray energies.

[0069] In this way, the Bragg equation can be satisfied over a larger range of angles, and one configuration of the X-ray source 110 and the X-ray detector 130 can be used to accommodate many different crystal types.

[0070] In another embodiment, the X-ray source 110 can utilize a wide range of angles to determine the type of crystalline structure possessed by the workpiece. Once the crystalline structure is determined, the X-ray source 110 and the X-ray detector 130 can be moved to an angle appropriate for the crystalline structure. For example, the X-ray source 110 and the X-ray detector 130 can be movable so that they can be moved to facilitate setting the appropriate angle. In this case, the X-ray source 110 can also incorporate a collimator 115, which enables the use of a narrower range of angles for the emitted X-ray beam 120. In this manner, the controller 280 performs a coarse rocking curve test to determine the crystalline structure and then performs a fine rocking curve test to identify the steering direction.

[0071] The above-described embodiments of the present application can have numerous advantages. Using XRD in the processing chamber enables precise control of the angle of incidence of the ion beam 230. This maximizes the degree of guidance in the workpiece. Guiding can enable deeper implants for a given energy. In some tests, the peak concentration of ions can be deepened by 0.5 microns when a guided implant is performed compared to an unguided implant. In another test, the concentration of ions can be more box-shaped when a guided implant is performed. Additionally, guiding can reduce the amount of damage caused by the implant. In some embodiments, the amount of damage is reduced sufficiently that the workpiece is not heated prior to implantation, thereby reducing the time spent in the processing chamber. Additionally, using XRD reduces the likelihood of workpiece misorientation and, therefore, can achieve a greater yield.

[0072] The scope of the present disclosure is not limited by the specific embodiments described herein. In fact, various other embodiments of the present disclosure and various modifications to the present disclosure in addition to the embodiments and modifications described herein will be apparent to those skilled in the art from the above description and accompanying drawings. Therefore, these other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein in the context of specific embodiments in specific environments for specific purposes, those skilled in the art will recognize that the utility of the present disclosure is not limited thereto and may be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth below should be understood in light of the full scope and spirit of the disclosure described herein.

Claims

1. An ion implanter comprising: an ion source for generating an ion beam; a platen for supporting a workpiece having a crystalline structure; an X-ray source for generating an X-ray beam, wherein at least a portion of the X-ray beam strikes the workpiece to generate diffracted X-rays; an X-ray detector positioned to receive the diffracted X-rays; as well as a controller in communication with the X-ray source, the platen, and the X-ray detector, wherein the controller includes a memory device containing instructions that, when executed by the controller, enable the ion implanter to: performing a rocking curve test after the workpiece is placed on the platen; as well as An orientation of the platen is calculated for an ion implantation process based on the results of the rocking curve test to facilitate directing the ion beam into the crystalline structure of the workpiece.

2. The ion implanter of claim 1 , wherein the memory device further comprises instructions that, when executed by the controller, enable the ion implanter to perform an ion implantation process while the workpiece is positioned on the platen in the previously calculated orientation.

3. The ion implanter of claim 1 , wherein the rocking curve test is performed while the platen is disposed in a loading position, wherein the clamping surface of the platen is horizontal in the loading position.

4. The ion implanter of claim 1, wherein the rocking curve test is performed at a plurality of locations on the workpiece.

5. The ion implanter of claim 4, wherein the workpiece is rotated about an axis passing through the center of the platen and perpendicular to the clamping surface of the platen so that the X-ray beam impinges on a new location on the workpiece.

6. The ion implanter of claim 4, wherein the ion beam has a width in an X direction and a height in a Y direction, wherein translation of the platen in the Y direction causes the X-ray beam to impinge on a new location on the workpiece.

7. The ion implanter of claim 1 , wherein the platen is adapted to tilt about an X-axis and a Y-axis, wherein the X-axis passes through a center of the platen and is parallel to a width of the ion beam, and the Y-axis passes through the center of the platen and is parallel to a height of the ion beam, and wherein a rocking curve test is performed when the platen is tilted about the X-axis to determine an X-tilt angle at which the diffracted X-rays have a maximum intensity and when the platen is tilted about the Y-axis to determine a Y-tilt angle at which the diffracted X-rays have a maximum intensity, and wherein the controller calculates an orientation to be used for the ion implantation process based on the X-tilt angle and the Y-tilt angle determined during the rocking curve test.

8. The ion implanter of claim 7 , wherein the X-ray detector is a two-dimensional sensor array such that the estimated X tilt angle and the estimated Y tilt angle are determined without tilting the workpiece, and the rocking curve test is performed by tilting about the estimated X tilt angle and the estimated Y tilt angle.

9. The ion implanter of claim 1 , further comprising a collimator positioned to receive the X-ray beam from the X-ray source and to collimate the X-ray beam to provide the portion of the X-ray beam to the workpiece.

10. The ion implanter of claim 1, wherein the platen, the X-ray source, and the X-ray detector are disposed in a processing chamber configured to receive the ion beam.

11. The ion implanter of claim 10, wherein the X-ray source and the X-ray detector are disposed in a top portion of the processing chamber.

12. The ion implanter of claim 1 , wherein the platen is disposed in a processing chamber configured to receive the ion beam, and at least one of the X-ray source and the X-ray detector is disposed outside the processing chamber, and a window is disposed in the processing chamber to allow X-rays to pass between the processing chamber and an environment outside the processing chamber.

13. The ion implanter of claim 1, wherein the X-ray source and the X-ray detector are movable to adjust the angle at which the X-ray beam strikes the workpiece.

14. An ion implanter comprising: an ion source for generating an ion beam; a processing chamber, wherein the ion beam enters the processing chamber, wherein a stage is disposed in the processing chamber; an auxiliary chamber, separated from the processing chamber, the auxiliary chamber comprising: an auxiliary table suitable for supporting a workpiece having a crystalline structure; an X-ray source for generating an X-ray beam, wherein at least a portion of the X-ray beam strikes the workpiece to generate diffracted X-rays; as well as an X-ray detector positioned to receive the diffracted X-rays; as well as a controller in communication with the X-ray source, the auxiliary stage, the X-ray detector, and the stage, wherein the controller includes a memory device containing instructions that, when executed by the controller, enable the ion implanter to: performing a rocking curve test after the workpiece is placed on the auxiliary platen; calculating an orientation of the workpiece for an ion implantation process based on the results of the rocking curve test to facilitate directing the ion beam into the crystalline structure of the workpiece; as well as The previously calculated orientation is used to orient the platen in the processing chamber after the workpiece has been placed on the platen.

15. The ion implanter of claim 14 , further comprising a second X-ray source and a second X-ray detector, wherein the memory device further comprises instructions that, when executed by the controller, enable the ion implanter to: A second rocking curve test is performed in the processing chamber using the second X-ray source and the second X-ray detector after the workpiece has been transferred to the processing chamber.

16. The ion implanter of claim 15, wherein the second X-ray source and the second X-ray detector are disposed in the processing chamber.

17. The ion implanter of claim 15 , wherein the platen includes a heater, wherein the memory device further comprises instructions that, when executed by the controller, enable the ion implanter to: heating the platen after the workpiece is transferred to the processing chamber; and The second rocking curve test is performed in the processing chamber using the second X-ray source and the second X-ray detector after the workpiece has reached a desired temperature.

18. The ion implanter of claim 17, wherein the second X-ray source and the second X-ray detector are disposed in the processing chamber.

19. The ion implanter of claim 14 , wherein the X-ray detector comprises a two-dimensional sensor array such that an estimated X tilt angle and an estimated Y tilt angle are determined during the rocking curve test, and wherein a second rocking curve test is performed in the processing chamber by tilting the platen about the estimated X tilt angle and the estimated Y tilt angle.

20. The ion implanter of claim 14, wherein the memory device further comprises instructions that, when executed by the controller, enable the ion implanter to perform an ion implantation process while the workpiece is positioned on the platen in the previously calculated orientation.

21. The ion implanter of claim 14, wherein the rocking curve test is performed at a plurality of locations on the workpiece.

22. The ion implanter of claim 21, wherein the workpiece is rotated about an axis passing through the center of the auxiliary platen and perpendicular to the clamping surface of the auxiliary platen so that the X-ray beam impinges on a new location on the workpiece.

23. The ion implanter of claim 22, wherein the ion beam has a width in an X direction and a height in a Y direction, wherein translation of the auxiliary stage in the Y direction causes the X-ray beam to impinge on a new location on the workpiece.

24. The ion implanter of claim 14 , wherein the auxiliary stage is adapted to tilt about an X-axis and a Y-axis, wherein the X-axis passes through a center of the auxiliary stage and is parallel to a width of the ion beam, and the Y-axis passes through the center of the auxiliary stage and is parallel to a height of the ion beam, and wherein a rocking curve test is performed when the auxiliary stage is tilted about the X-axis to determine an X-tilt angle at which the diffracted X-rays have a maximum intensity and when the auxiliary stage is tilted about the Y-axis to determine a Y-tilt angle at which the diffracted X-rays have a maximum intensity, and wherein the controller calculates an orientation to be used for the ion implantation process based on the X-tilt angle and the Y-tilt angle determined during the rocking curve test.

25. The ion implanter of claim 24 , wherein the X-ray detector is a two-dimensional sensor array such that the estimated X tilt angle and the estimated Y tilt angle are determined without tilting the workpiece, and the rocking curve test is performed by tilting about the estimated X tilt angle and the estimated Y tilt angle.

26. The ion implanter of claim 14, further comprising a collimator positioned to receive the X-ray beam from the X-ray source and to collimate the X-ray beam to provide the portion of the X-ray beam to the workpiece.

27. The ion implanter of claim 14, wherein the controller further comprises instructions that, when executed by the controller, enable the ion implanter to: determining the identity of the workpiece subjected to the rocking curve test; and The identity of the artifact and the orientation associated with the artifact are stored for future use.

28. The ion implanter of claim 27, wherein the controller further comprises instructions that, when executed by the controller, enable the ion implanter to: again detecting the identity of the workpiece before placing the workpiece on the platen; and The previously calculated orientation is selected based on the identity of the platen.

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