A wafer position calibration method and apparatus, charged particle beam device

Abstract

The application provides a wafer position calibration method and device and a charged particle beam device. A surface of a wafer has at least a first mark and a second mark. A sample table receives the wafer at a wafer loading position. A first image acquisition device is arranged above the wafer loading position. The calibration method comprises: planning a transmission path of the wafer and / or a position of the sample table, so that when the wafer is placed on a wafer support disc, the first mark falls within a field of view range of the first image acquisition device; acquiring a first image containing the first mark during a process in which the wafer support disc adsorbs the wafer, or after the wafer support disc completes adsorption of the wafer; moving the sample table based on relative position information between the first mark and the second mark, so that the second mark falls within the field of view range of the first image acquisition device; acquiring a second image containing the second mark; and obtaining a calibration parameter of the wafer position according to the first image and the second image. The above method improves machine throughput and wafer calibration efficiency.

Description

Technical Field

[0001] This invention relates to the field of semiconductor quantity detection, and in particular to a wafer position calibration method and apparatus, and a charged particle beam device. Background Technology

[0002] With the continuous miniaturization of semiconductor devices, semiconductor devices in the tens of nanometers range have become mainstream in recent years. In the production process of these semiconductor devices with fine structures, scanning electron microscopy (SEM) is widely used for defect detection of semiconductor devices due to its high resolution and ability to provide detailed images of the surface morphology of samples (e.g., wafers).

[0003] The working principle of scanning electron microscopy is based on the interaction between an electron beam and a wafer to generate signals, such as secondary electrons (SE) and backscattering electrons (BSE). These signals are collected by a detector and converted into images to reveal the microstructure and defects on the wafer surface.

[0004] Before using SEM to measure or observe the object under test, it is necessary to perform coarse alignment and fine alignment of the object under test in sequence in order to determine the position of the object under test and accurately move the area to be measured on the object under the SEM.

[0005] Traditional coarse alignment requires waiting until the object under test is moved to the observation position before aligning the optical microscope (OM). However, moving the object under test into and out of the OM's field of view takes time, and OM alignment is time-consuming (usually around 5 seconds). This results in low throughput of the SEM equipment and reduces efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for calibrating wafer position, and a charged particle beam device. This method acquires a first image (containing a first mark on the wafer surface) and a second image (containing a second mark on the wafer surface) at the wafer loading position to obtain calibration parameters for the wafer position, thereby optimizing the sample stage's movement trajectory and significantly improving the throughput and calibration efficiency of the SEM instrument. The acquisition of the first image occurs during the wafer carrier's adsorption of the wafer (approximately a few seconds to tens of seconds) or after the wafer carrier has completed adsorption. Acquiring the first image after the wafer carrier has completed adsorption eliminates the need for the step of moving the sample stage from the wafer loading position to the area under the optical microscope for image acquisition, as is common in traditional methods, reducing process time. Acquiring the first image during the wafer carrier's adsorption process also makes full use of the time from the wafer's initial contact with the wafer carrier to the stable adsorption of the wafer (approximately a few seconds to tens of seconds, also known as the adsorption stabilization time), further shortening the overall process time.

[0007] To achieve the above objectives, the present invention provides a wafer position calibration method for calibrating the position of a wafer on a sample stage. The sample stage is provided with a wafer carrier disk for supporting and fixing the wafer. The surface of the wafer has at least a first mark and a second mark. The sample stage receives the wafer at a wafer loading position. A first image acquisition device is provided above the wafer loading position. The calibration method includes:

[0008] Plan the transport path of the wafer and / or move the position of the sample stage so that when the wafer is placed on the wafer carrier, the first mark falls within the field of view of the first image acquisition device;

[0009] During the process of the wafer carrier adsorbing the wafer, or after the wafer carrier has finished adsorbing the wafer, a first image containing the first mark is acquired;

[0010] The sample stage is moved based on the relative position information between the first mark and the second mark, so that the second mark falls into the field of view of the first image acquisition device;

[0011] Acquire a second image including the second marker;

[0012] The calibration parameters for the wafer position are obtained based on the first image and the second image.

[0013] Optionally, the sample stage can move along a trajectory from the wafer loading position to the wafer observation position where the observer is located, and the calibration method further includes:

[0014] The movement trajectory of the sample stage is adjusted according to the calibration parameters so that the area to be observed on the wafer is moved into the observable range of the observation instrument.

[0015] Optionally, the calibration parameters include at least one of translation parameters and rotation parameters.

[0016] Optionally, obtaining the calibration parameters for the wafer position based on the first image and the second image includes:

[0017] The coordinates of the first mark in the sample stage coordinate system are obtained based on the first image;

[0018] The coordinates of the second mark in the sample stage coordinate system are obtained based on the second image;

[0019] Based on the position information of the first and second marks on the wafer, and the coordinates of the first and second marks, the coordinates of the wafer in the sample stage coordinate system and the rotation angle of the wafer are obtained.

[0020] The translation parameters are set according to the coordinates of the wafer in the sample stage coordinate system, and the rotation parameters are set according to the rotation angle of the wafer.

[0021] Optionally, the wafer position calibration method further includes:

[0022] Adjust the transport path of the next wafer and / or move the position of the sample stage according to the calibration parameters so that when the next wafer is placed on the wafer carrier, the deviation between the first mark and the center of the field of view of the first image acquisition device is within a preset range.

[0023] Optionally, the first mark and the second mark include: a cross-shaped mark, a rectangular mark, or a circular mark.

[0024] Optionally, the first image acquisition device may include a camera or an optical microscope.

[0025] Optionally, the camera may employ a telecentric lens or a zoom lens.

[0026] Optionally, the observation instrument includes an electron microscope.

[0027] Optionally, after the area to be observed on the wafer moves into the observable range of the observation instrument, the method further includes:

[0028] Perform the electron microscope alignment procedure.

[0029] The present invention also provides a wafer positioning calibration device, comprising:

[0030] A sample stage that can move along a trajectory from the wafer loading position to the wafer observation position;

[0031] A wafer carrier disk is disposed on the sample stage for supporting and adsorbing and fixing the wafer; the surface of the wafer has at least a first mark and a second mark;

[0032] The first image acquisition device is positioned above the wafer loading location;

[0033] A processor is connected to the first image acquisition device and the sample stage; the processor is used to plan the transport path of the wafer and / or move the position of the sample stage so that when the wafer is placed on the wafer carrier, the first mark falls within the field of view of the first image acquisition device; during the process of the wafer carrier adsorbing the wafer, or after the wafer carrier has completed adsorbing the wafer, the processor controls the first image acquisition device to acquire a first image containing the first mark;

[0034] The processor is also configured to control the sample stage to move so that the second mark falls into the field of view of the first image acquisition device, and to control the first image acquisition device to acquire a second image including the second mark;

[0035] The processor obtains the calibration parameters of the wafer position based on the first image and the second image.

[0036] Optionally, the wafer observation position is equipped with an observation instrument, and the processor is further configured to adjust the movement trajectory of the sample stage according to the calibration parameters, so that the area to be observed on the wafer is moved into the observable range of the observation instrument.

[0037] Optionally, the processor adjusts the transport path of the next wafer and / or moves the position of the sample stage according to the calibration parameters so that when the next wafer is placed on the wafer carrier, the deviation between the first mark and the center of the field of view of the first image acquisition device is within a preset range.

[0038] Optionally, the first image acquisition device includes an optical microscope or a camera.

[0039] Optionally, the camera may employ a telecentric lens or a zoom lens.

[0040] Optionally, a second image acquisition device may be provided above the wafer observation position.

[0041] Optionally, the sample stage is further provided with an annular electrode, which surrounds the outer periphery of the wafer carrier disk.

[0042] The present invention also provides a charged particle beam device, comprising:

[0043] The main chamber includes a wafer loading position and a wafer observation position;

[0044] A particle beam irradiation device is located in the main chamber and at the wafer observation position;

[0045] As described in this invention, a wafer positioning calibration device;

[0046] The sample stage, the wafer carrier disk, and the first image acquisition device are all located in the main chamber.

[0047] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0048] 1) The wafer position calibration method and apparatus, and charged particle beam device of the present invention, acquire a first image and a second image containing a first mark and a second mark at the wafer loading position to obtain calibration parameters for the wafer position, thereby achieving coarse alignment of the wafer. The acquisition of the first image occurs during the wafer carrier disk's adsorption of the wafer, or after the wafer carrier disk has completed adsorption of the wafer. Compared with traditional coarse alignment at the wafer observation position, the present invention eliminates the need to move the wafer into and out of the OM field of view of the wafer observation position via a sample stage, thereby optimizing the sample stage's movement trajectory, reducing sample stage movement time, and improving the throughput of the equipment and the wafer calibration efficiency. Acquiring the first image during the adsorption process can further shorten the overall process time.

[0049] 2) The present invention also performs feedback compensation on the transmission path of the next wafer based on the obtained calibration parameters, ensuring that the first mark falls in the center of the field of view of the first image acquisition device, thereby optimizing the transmission accuracy of the wafer in the early transmission process (before the wafer carrier disk receives the wafer).

[0050] 3) After wafer processing, due to factors such as fluctuations in process parameters, the mechanical precision of the equipment, and differences in the microstructure of the wafer material, the thickness and deformation of each wafer vary. The first image acquisition device of this invention can be a camera with a zoom lens, which can overcome the influence of changes in object distance by adjusting the shooting focal length, thus ensuring the imaging quality of the first and second images.

[0051] 4) The first image acquisition device of the present invention can be a camera with a telecentric lens, which can achieve clear imaging over a wider focal range, without the need to take multiple images at once in the depth of focus direction, thus improving the throughput of the machine.

[0052] 5) This invention also includes a second image acquisition device (e.g., an optical microscope) positioned above the wafer observation location. Since the first image acquisition device is located at the wafer loading position, relatively close to the side wall of the main chamber, space constraints make it difficult to capture images of the flat or notch located at the wafer edge. However, the wafer observation location is mostly located in the center of the main chamber. By placing a second image acquisition device above the wafer observation location, the problem of limited space making it difficult to capture images of the flat or notch can be solved. Attached Figure Description

[0053] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0054] Figure 1 This is a top view of the wafer in an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the wafer carrier disk and the ring electrode being disposed on the sample stage in an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the SEM machine in an embodiment of the present invention;

[0057] Figure 4 This is a flowchart of a wafer positioning calibration method in an embodiment of the present invention;

[0058] Figure 5 This is a schematic diagram showing the position of the first mark in the first image in the sample stage coordinate system in an embodiment of the present invention;

[0059] Figure 6 This is a schematic diagram showing the position of the second mark in the second image in the sample stage coordinate system in an embodiment of the present invention;

[0060] Figure 7 This is a flowchart of a wafer positioning calibration method in one embodiment of the present invention;

[0061] Figure 8 This is a flowchart of a wafer positioning calibration method in another embodiment of the present invention;

[0062] Figure 9 This is a schematic diagram of the structure of the SEM machine in another embodiment of the present invention. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0065] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0066] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0067] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0068] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0069] When observing a wafer using a SEM, the wafer needs to be placed on the wafer carrier tray of the sample stage (with a placement accuracy of approximately 100 micrometers), and then the sample stage moves the wafer below the SEM. Due to mechanical errors, slight positional shifts and rotations may occur during wafer placement, making it impossible to ensure that the wafer is always precisely centered on the wafer carrier tray. This results in the inability to accurately move the area to be observed on the wafer into the SEM's field of view (10 to 30 micrometers) when the sample stage moves the wafer from the wafer loading position to the wafer observation position. For high-precision SEM observations, such positional errors are unacceptable. Therefore, wafer position calibration is necessary before formal observation.

[0070] As described in the background section, the traditional calibration process involves moving the wafer to the observation position using a sample stage. An optical microscope positioned at this location is then used to perform initial alignment (OM) (also known as coarse alignment) of the wafer. The optical microscope has a field of view of approximately 1000 micrometers, allowing alignment marks to be covered within its range. The wafer is then moved under the SEM via the sample stage for SEM alignment (also known as fine alignment). This calibration process involves a relatively long sample stage movement path, reducing calibration efficiency. Furthermore, the time spent on wafer adsorption and fixation is not fully utilized, resulting in low throughput for the SEM equipment.

[0071] To address the aforementioned problems, this invention provides a wafer position calibration method and apparatus, and a charged particle beam device, which overcomes the shortcomings of existing technologies. By acquiring a first image (containing a first mark on the wafer surface) and a second image (containing a second mark on the wafer surface) at the wafer loading position to obtain the wafer position calibration parameters, this replaces the coarse alignment commonly used in traditional methods at the wafer observation position, optimizes the sample stage movement trajectory, and shortens the overall process time. The acquisition of the first image occurs during the wafer carrier's adsorption of the wafer, or after the wafer carrier has completed adsorption. Acquiring the first image during the adsorption process can further shorten the overall process time.

[0072] This invention provides a method for calibrating the position of a wafer on a sample stage. Figure 1 As shown in the embodiment of the present invention, the surface of the wafer W has at least a first mark 11 and a second mark 12. Figure 1 The first mark 11 and the second mark 12 are cross-shaped marks. In other embodiments, the first mark 11 and the second mark 12 may also be rectangular marks or circular marks.

[0073] like Figure 2As shown, a wafer carrier disk 183 is provided on the sample stage 181 for supporting and adsorbing the wafer W. The wafer carrier disk 183 can be an electrostatic chuck, which generates electrostatic adsorption force through electrostatic electrodes (not shown in the figure) within the electrostatic chuck to adsorb and fix the wafer W. Due to the influence of the shape of the electrostatic electrodes, the adsorption voltage applied to the electrostatic electrodes, and the material of the electrostatic chuck, it usually takes several seconds to tens of seconds to achieve stable adsorption of the wafer W.

[0074] like Figure 3 As shown, wafer W follows a planned transport path, passing sequentially through the Equipment Front-End Module 110, the gaslock chamber 120, and the transport chamber 130 before entering the main chamber 160. The main chamber 160 includes a wafer loading position 161 and a wafer observation position 162. A sample stage 181 is located within the main chamber 160 and can move along a trajectory from the wafer loading position 161 to the wafer observation position 162. The sample stage 181 receives wafer W at the wafer loading position 161, and a first image acquisition device 191 is positioned above the wafer loading position 161. It should be noted that "above" here is not limited to strictly above, but also includes diagonally above; this application does not impose such a limitation. The wafer observation position 162 is equipped with an observation instrument 171 for revealing the microstructure and defects on the surface of wafer W. In one embodiment of the invention, the observation instrument 171 includes a SEM; in another embodiment, the observation instrument includes an ion microscope.

[0075] In embodiments of the present invention, such as Figure 4 As shown, the wafer positioning calibration method includes the following steps:

[0076] S10. Plan the transport path of wafer W (for transporting wafer W to wafer carrier 183) and / or move the position of sample stage 181 so that when wafer W is placed on wafer carrier 183, the first mark 11 falls within the field of view of the first image acquisition device 191 (e.g., ...). Figure 5 (as shown);

[0077] In one embodiment, the first image acquisition device 191 employs an optical microscope. Figure 1 , Figure 5 , Figure 6 The dashed box in the figure represents the field of view of the optical microscope.

[0078] After wafer W is processed, due to factors such as fluctuations in process parameters, the mechanical precision of the equipment, and differences in the microstructure of the wafer W material, the thickness and degree of deformation of each wafer W vary. In a preferred embodiment, the first image acquisition device 191 is a camera with a zoom lens, which can overcome the influence of changes in object distance by adjusting the shooting focal length, thus ensuring the imaging quality of the first image.

[0079] In another preferred embodiment, the first image acquisition device 191 is a camera with a telecentric lens, which can achieve clear imaging over a wider focal length range without having to take multiple images at once in the depth of focus direction, thus improving the throughput of the machine.

[0080] S20. During the process of adsorbing wafer W on wafer carrier 183, or after wafer carrier 183 has finished adsorbing wafer W, a first image containing the first marker 11 is acquired.

[0081] In this embodiment of the invention, the acquisition of the first image occurs during the adsorption of wafer W, or after wafer carrier 183 has completed adsorption of wafer W. Acquiring the first image after wafer carrier 183 has completed adsorption of wafer W eliminates the need for the step of moving the sample stage 181 from the wafer loading position 161 to the area under the optical microscope for image acquisition, as is common in conventional methods, thus reducing process time. Acquiring the first image during wafer carrier 183 adsorption of wafer W also makes full use of the time from the moment wafer W contacts wafer carrier 183 until wafer carrier 183 stably adsorbs wafer W (approximately a few seconds to tens of seconds, also known as the adsorption stabilization time), further shortening the overall process time.

[0082] S30. Based on the relative position information between the first mark 11 and the second mark 12, move the sample stage 181 so that the second mark 12 falls within the field of view of the first image acquisition device 191 (e.g., ...). Figure 6 (as shown);

[0083] In this embodiment of the invention, the movement of the sample stage 181 is controlled by the processor 151 (see...). Figure 3 The relative position information between the first mark 11 and the second mark 12 is pre-stored in the processor 151. The processor 151 controls the movement of the sample stage 181 (including horizontal rotation and / or translation) according to the stored relative position information, so that the second mark 12 falls within the field of view of the first image acquisition device 191.

[0084] S40. Acquire a second image including the second marker 12;

[0085] S50. Obtain the calibration parameters for the wafer position based on the first image and the second image.

[0086] Steps S10 to S50 described above can replace the coarse alignment step commonly used in traditional calibration processes at the wafer observation position 162. In this embodiment of the invention, the sample stage 181 is still in the wafer loading position 161 when acquiring the first and second images, and the sample stage 181 itself also needs to receive the wafer W at the wafer loading position 161. Therefore, there is no need to add an extra moving path for the sample stage 181 for acquiring the first and second images. After the first and second images are acquired, the sample stage 181 can carry the wafer W directly to the bottom of the SEM. Compared with the traditional coarse alignment method, this invention optimizes the moving trajectory of the sample stage 181 and reduces the moving time of the wafer W. This further improves the throughput of the instrument and the calibration efficiency of the wafer W.

[0087] In some embodiments, obtaining calibration parameters for the wafer position based on the first image and the second image includes:

[0088] S51. Obtain the coordinates of the first mark 11 in the sample stage coordinate system based on the first image;

[0089] When receiving wafer W, the position information of sample stage 181 (hereinafter referred to as receiving position information for ease of description) has been planned in step S10. The movement and planning of sample stage 181 are controlled by processor 151, therefore the position information of sample stage 181 in the main chamber 160 (including the receiving position information) is known. For example... Figure 5 , Figure 6 As shown, the sample stage 181 is rectangular (this is only an example and is not intended to limit the invention). In this embodiment of the invention, a sample stage coordinate system is established based on the received position information. The origin of the sample stage coordinate system is the center of the sample stage 181, and the x-axis and y-axis of the sample stage coordinate system are parallel to the two mutually perpendicular right-angled sides of the sample stage 181, respectively.

[0090] The transformation relationship between the image coordinate system of the first image and the sample stage coordinate system has been pre-defined. Therefore, based on the coordinates of the first mark 11 in the first image, the coordinates of the first mark 11 in the sample stage coordinate system can be determined.

[0091] S52. Obtain the coordinates of the second mark 12 in the sample stage coordinate system based on the second image;

[0092] After acquiring the first image, the sample stage 181 rotates horizontally and / or translates to acquire the second image. Based on the rotation angle of the sample stage 181 and the translation amount of the sample stage 181 along the x and y axes, the processor 151 converts the coordinates of the second mark 12 in the second image into coordinates in the sample stage coordinate system.

[0093] It should be noted that in the traditional coarse alignment process, the sample stage 181 also needs to be rotated and translated to acquire images of two different marks on the wafer W. Therefore, in step S52, the rotation and translation operation of the sample stage 181 when acquiring the second image will not increase the overall process time.

[0094] S53. Based on the position information of the first mark 11 and the second mark 12 on the wafer W, and the coordinates of the first mark 11 and the second mark 12, the coordinates of the wafer W in the sample stage coordinate system and the rotation angle of the wafer W are obtained.

[0095] Given the relative position information between the first mark 11 and the second mark 12, the coordinates of the first mark 11 in the sample stage coordinate system, and the coordinates of the second mark 12 in the sample stage coordinate system, the coordinates of any point on the wafer W in the sample stage coordinate system can be obtained.

[0096] S54. Set the translation parameters according to the coordinates of wafer W in the sample stage coordinate system, and set the rotation parameters according to the rotation angle of wafer W.

[0097] The calibration parameters include at least one of translation and rotation parameters. In this embodiment of the invention, the translation parameter is the offset of the center of the wafer W relative to the center of the sample stage 181 along the x-axis and y-axis. For example... Figure 1 , Figure 5 , Figure 6 As shown, a positioning mark 13 is provided on the edge of the wafer to mark the crystal orientation of the wafer W and to ensure precise alignment of the wafer W in the semiconductor manufacturing equipment. The positioning mark 13 can be a positioning edge (flat) or a notch. In this embodiment of the invention, the positioning mark 13 of the wafer W is a V-shaped notch. In the sample stage coordinate system, the coordinates of the V-shaped notch and the coordinates of the wafer center can be used to obtain a straight line, and the angle between this straight line and the y-axis is the rotation parameter of the wafer W.

[0098] In one embodiment, such as Figure 7 As shown, the wafer positioning calibration method also includes:

[0099] S60. Adjust the movement trajectory of the sample stage 181 according to the calibration parameters of the wafer position so that the area to be observed on the wafer W is moved into the observable range of the observation instrument 171.

[0100] The observation instrument 171 includes an electron microscope. Once the area to be observed on the wafer W is moved into the observable range of the observation instrument 171, such as... Figure 7 As shown, the wafer positioning calibration method also includes:

[0101] S70. Perform the electron microscope alignment procedure.

[0102] Step S70 is used to perform fine alignment on wafer W.

[0103] In another embodiment, such as Figure 8 As shown, the wafer positioning calibration method also includes:

[0104] S60' Adjust the transmission path of the next wafer W and / or move the position of the sample stage 181 according to the calibration parameters so that when the next wafer W is placed on the wafer carrier 183, the deviation between the first mark 11 and the center of the field of view of the first image acquisition device 191 is within a preset range.

[0105] The strong electric field formed between wafer W and wafer carrier disk 183 interferes with the potential distribution around wafer W, causing the electron beam to be easily deflected when observing the wafer edge region. To solve this problem, such as Figure 2 As shown, a ring electrode 182 is disposed on the sample stage 181, surrounding the outer periphery of the wafer carrier disk 183 and concentric with the wafer carrier disk 183. By adjusting the correction voltage applied to the ring electrode 182, the electron beam is made to irradiate the surface of the wafer W perpendicularly. If the wafer W cannot be centered on the wafer carrier disk 183, the correction voltage applied to the ring electrode 182 needs to be significantly adjusted when observing different positions in the wafer edge region, which will affect the measurement accuracy and reduce the overall process efficiency.

[0106] During the process of creating a process flow (Create Recipe), the transfer path of wafer W, the position of sample stage 181, and the position of first image acquisition device 191 are configured such that when wafer W is placed centered on wafer carrier disk 183, the first mark 11 is located at a specific position within the field of view of the first image acquisition device 191 (in this embodiment of the invention, the specific position is the center of the field of view of the first image acquisition device 191).

[0107] However, due to mechanical errors, the position of wafer W on wafer carrier 183 is different each time. By executing step S60', the deviation between the first mark 11 and the center of the field of view is further reduced when the next wafer W is placed on wafer carrier 183, thus further improving the alignment accuracy of wafer W and ring electrode 182.

[0108] As a second aspect of the present invention, a wafer positioning calibration device is also provided, such as... Figure 3 As shown, it includes: a sample stage 181, a first image acquisition device 191, and a processor 151.

[0109] like Figure 3As shown, the sample stage 181 can move along a trajectory from the wafer loading position 161 to the wafer observation position 162, where an observation instrument 171 is provided. The sample stage 181 is provided with a wafer carrier disk 183 and an annular electrode 182 (surrounding the outer periphery of the wafer carrier disk 183). The wafer carrier disk 183 is used to support and hold the wafer W in place, and the surface of the wafer W has at least a first mark 11 and a second mark 12.

[0110] like Figure 3 As shown, the first image acquisition device 191 is positioned above the wafer loading position 161. In one embodiment, the first image acquisition device 191 is an optical microscope. In another embodiment, the first image acquisition device 191 is a camera employing a telecentric lens or a zoom lens.

[0111] The processor 151 is connected to the first image acquisition device 191 and the sample stage 181. The processor 151 is used to plan the transport path of the wafer W and / or move the position of the sample stage 181 so that when the wafer W is placed on the wafer carrier 183, the first mark 11 falls within the field of view of the first image acquisition device 191.

[0112] During the process of wafer W being adsorbed by wafer carrier 183, or after wafer carrier 183 has completed adsorption of wafer W, processor 151 controls first image acquisition device 191 to acquire a first image including first mark 11. Processor 151 also controls sample stage 181 to move so that second mark 12 falls into the field of view of first image acquisition device 191, and controls first image acquisition device 191 to acquire a second image including second mark 12.

[0113] The processor 151 obtains the calibration parameters of the wafer position based on the first image and the second image, and adjusts the movement trajectory of the sample stage 181 according to the calibration parameters, so that the area to be observed on the wafer W is moved into the observable range of the observation instrument 171.

[0114] The processor 151 also adjusts the transport path of the next wafer W and / or moves the position of the sample stage 181 according to the calibration parameters so that when the next wafer W is placed on the wafer carrier 183, the deviation between the first mark 11 and the center of the field of view of the first image acquisition device 191 is within a preset range.

[0115] In another embodiment, such as Figure 9 As shown, a second image acquisition device 192 is provided above the wafer observation position 162. The second image acquisition device 192 can be an optical microscope with a large field of view.

[0116] In the creation of some process flows, it is necessary to acquire images containing positioning markers 13 in order to plan the transport path of wafer W.

[0117] When planning the transport path of wafer W, a partial edge contour image (including positioning marks 13) of wafer W is acquired by the second image acquisition device 192. Based on the standard equation of a circle, the entire edge contour image of wafer W can be fitted, thus determining the coordinates of each point on wafer W in the sample stage coordinate system. The rotation angle of wafer W can be determined based on the positioning marks 13 and the coordinates of the center of wafer W in the sample stage coordinate system. Based on the coordinates of the center of wafer W in the sample stage coordinate system and the rotation angle of wafer W, it can be determined whether wafer W is placed on the wafer carrier 183 in the planned position. If not, the transport path of wafer W is further adjusted.

[0118] Since the first image acquisition device 191 is located at the wafer loading position 161, which is relatively close to the side wall of the main chamber 160, it is difficult to capture images of the positioning edge or groove located at the edge of the wafer W due to space constraints. The wafer observation position 162 is mostly located in the middle of the main chamber 160. By setting the second image acquisition device 192 above the wafer observation position 162, the problem of space constraints making it difficult to capture images of the positioning edge or groove can be solved.

[0119] As a third aspect of the present invention, a charged particle beam device is also disclosed, comprising:

[0120] The main chamber 160 includes a wafer loading position 161 and a wafer observation position 162;

[0121] The particle beam irradiation device is located in the main chamber 160 and at the wafer observation position 162;

[0122] As described in this invention, a wafer positioning calibration device;

[0123] The sample stage 181, the wafer carrier disk 183, and the first image acquisition device 191 are all located in the main chamber 160.

[0124] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0125] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for calibrating wafer positioning, characterized in that, For calibrating the position of a wafer on a sample stage, the sample stage is provided with a wafer carrier tray for supporting and fixing the wafer. The surface of the wafer has at least a first mark and a second mark. The sample stage receives the wafer at a wafer loading position. A first image acquisition device is provided above the wafer loading position. The calibration method includes: Plan the transport path of the wafer and / or move the position of the sample stage so that when the wafer is placed on the wafer carrier, the first mark falls within the field of view of the first image acquisition device; During the process of the wafer carrier adsorbing the wafer, or after the wafer carrier has finished adsorbing the wafer, a first image containing the first mark is acquired; The sample stage is moved based on the relative position information between the first mark and the second mark, so that the second mark falls into the field of view of the first image acquisition device; Acquire a second image including the second marker; The calibration parameters for the wafer position are obtained based on the first image and the second image.

2. The wafer positioning calibration method as described in claim 1, characterized in that, The sample stage can move along a trajectory from the wafer loading position to the wafer observation position where the observation instrument is located. The calibration method further includes: The movement trajectory of the sample stage is adjusted according to the calibration parameters so that the area to be observed on the wafer is moved into the observable range of the observation instrument.

3. The wafer positioning calibration method as described in claim 1 or 2, characterized in that, The calibration parameters include at least one of translation parameters and rotation parameters.

4. The wafer positioning calibration method as described in claim 3, characterized in that, The step of obtaining the calibration parameters for the wafer position based on the first image and the second image includes: The coordinates of the first mark in the sample stage coordinate system are obtained based on the first image; The coordinates of the second mark in the sample stage coordinate system are obtained based on the second image; Based on the position information of the first and second marks on the wafer, and the coordinates of the first and second marks, the coordinates of the wafer in the sample stage coordinate system and the rotation angle of the wafer are obtained. The translation parameters are set according to the coordinates of the wafer in the sample stage coordinate system, and the rotation parameters are set according to the rotation angle of the wafer.

5. The wafer positioning calibration method as described in claim 1, characterized in that, Also includes: Adjust the transport path of the next wafer and / or move the position of the sample stage according to the calibration parameters so that when the next wafer is placed on the wafer carrier, the deviation between the first mark and the center of the field of view of the first image acquisition device is within a preset range.

6. The wafer positioning calibration method as described in claim 1, characterized in that, The first mark and the second mark include: a cross-shaped mark, a rectangular mark, or a circular mark.

7. The wafer positioning calibration method as described in claim 1, characterized in that, The first image acquisition device includes a camera or an optical microscope.

8. The wafer positioning calibration method as described in claim 7, characterized in that, The camera uses a telecentric lens or a zoom lens.

9. The wafer positioning calibration method as described in claim 2, characterized in that, The observation instruments include an electron microscope.

10. The wafer positioning calibration method as described in claim 9, characterized in that, After the area to be observed on the wafer moves into the observable range of the observation instrument, the method further includes: Perform the electron microscope alignment procedure.

11. A wafer positioning calibration device, characterized in that, include: A sample stage that can move along a trajectory from the wafer loading position to the wafer observation position; A wafer carrier disk is disposed on the sample stage for supporting and adsorbing and fixing the wafer; the surface of the wafer has at least a first mark and a second mark; The first image acquisition device is positioned above the wafer loading location; A processor is connected to the first image acquisition device and the sample stage; The processor is used to plan the transport path of the wafer and / or move the position of the sample stage so that when the wafer is placed on the wafer carrier, the first mark falls within the field of view of the first image acquisition device; during the process of the wafer carrier adsorbing the wafer, or after the wafer carrier has completed adsorbing the wafer, the processor controls the first image acquisition device to acquire a first image containing the first mark. The processor is also configured to control the movement of the sample stage so that the second mark falls into the field of view of the first image acquisition device, and to control the first image acquisition device to acquire a second image including the second mark; The processor obtains the calibration parameters of the wafer position based on the first image and the second image.

12. The wafer positioning calibration apparatus as described in claim 11, characterized in that, The wafer observation position is equipped with an observation instrument, and the processor is further configured to adjust the movement trajectory of the sample stage according to the calibration parameters, so that the area to be observed on the wafer is moved into the observation range of the observation instrument.

13. The wafer positioning calibration apparatus as described in claim 11, characterized in that, The processor adjusts the transport path of the next wafer and / or moves the position of the sample stage according to the calibration parameters so that when the next wafer is placed on the wafer carrier, the deviation between the first mark and the center of the field of view of the first image acquisition device is within a preset range.

14. The wafer positioning calibration apparatus as described in claim 11, characterized in that, The first image acquisition device includes an optical microscope or a camera.

15. The wafer positioning calibration apparatus as described in claim 14, characterized in that, The camera uses a telecentric lens or a zoom lens.

16. The wafer positioning calibration apparatus as described in claim 11, characterized in that, A second image acquisition device is provided above the wafer observation position.

17. The wafer positioning calibration apparatus as described in claim 11, characterized in that, The sample stage is also provided with a ring electrode, which surrounds the outer periphery of the wafer carrier disk.

18. A charged particle beam device, characterized in that, include: The main chamber includes a wafer loading position and a wafer observation position; A particle beam irradiation device is located in the main chamber and at the wafer observation position; A wafer positioning calibration apparatus as described in any one of claims 11 to 17; The sample stage, the wafer carrier disk, and the first image acquisition device are all located in the main chamber.

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