Correction method of ion implantation angle

Abstract

A method for correcting an ion implantation angle includes: providing a test wafer; performing an ion implantation process on the test wafer, wherein the ion beam of the ion implantation process is a beam current with a preset beam divergence angle, so that the ion implantation angle on the surface of the test wafer gradually changes along a first direction, wherein the beam divergence angle is a divergence angle or a focusing angle, and the first direction is the divergence or focusing direction of the ion beam; obtaining a theoretical vertical implantation position of the ion implantation process on the test wafer; selecting a plurality of sampling points along the first direction on the surface of the test wafer; obtaining characteristic values ​​of the plurality of sampling points; obtaining the actual vertical implantation position of the ion beam on the test wafer based on the characteristic values; obtaining the position deviation between the actual vertical implantation position and the theoretical vertical implantation position in the first direction; and correcting the ion implantation angle of the ion implantation process based on the position deviation and the beam divergence angle. The present invention is conducive to more accurate correction of the ion implantation angle.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor technology, and in particular to a method for correcting an ion implantation angle. Background Art

[0002] As semiconductor technology develops towards Large Scale Integration (LSI) and Very Large Scale Integration Circuit (VLSI), the size of semiconductor devices is getting smaller and smaller, and the requirements for ion implantation are getting higher and higher, especially the requirements for the angle of ion implantation.

[0003] The main requirements of ion implantation in semiconductor manufacturing include uniformity and repeatability, energy purity, implantation angle accuracy, etc. As the size of semiconductor devices shrinks, ultra-shallow junction implantation, pocket structure implantation, Halo structure implantation, channel implantation, and high-precision sidewall implantation require very precise control of the ion implantation angle.

[0004] Due to the high-precision requirements for the ion implantation angle, the implantation angle of the ion implantation machine needs to be evaluated or calibrated during the ion implantation process. However, the existing angle calibration method is costly, and the accuracy and reliability of the calibration results are not high, which will produce certain errors and have a great impact on the high-precision manufacturing process. Summary of the invention

[0005] The problem solved by the embodiment of the present invention is to provide a method for correcting the ion implantation angle, which is conducive to more accurate correction of the ion implantation angle.

[0006] To solve the above problems, an embodiment of the present invention provides a method for correcting an ion implantation angle, comprising: providing a test wafer; performing ion implantation on the test wafer, wherein the ion beam of the ion implantation is a beam with a preset beam divergence angle, so that the ion implantation angle on the surface of the test wafer gradually changes along a first direction, wherein the beam divergence angle is a divergence angle or a focusing angle, and the first direction is the divergence or focusing direction of the ion beam; obtaining a theoretical vertical implantation position of the ion implantation on the test wafer; selecting a plurality of sampling points along the first direction on the surface of the test wafer; obtaining characteristic values ​​of the plurality of sampling points; obtaining an actual vertical implantation position of the ion beam on the test wafer based on the characteristic values; obtaining a position deviation between the actual vertical implantation position and the theoretical vertical implantation position in the first direction; and correcting the ion implantation angle of the ion implantation based on the position deviation and the beam divergence angle.

[0007] Optionally, in the step of performing ion implantation on the test wafer, the ion beam is symmetrically distributed on the plane where the beam divergence angle is located.

[0008] Optionally, in the step of performing ion implantation on the test wafer, the ion beam always completely covers the test wafer in the first direction.

[0009] Optionally, in the step of obtaining the theoretical vertical implantation position of the ion implantation region on the test wafer during the ion implantation process, the theoretical vertical implantation position coincides with the center of the test wafer.

[0010] Optionally, the step of performing ion implantation treatment on the test wafer includes: generating an ion beam, the ion beam being a strip beam diverging or focusing in a first direction; using the ion beam to perform multiple single-pass scans of the test wafer in a uniform reciprocating manner along a second direction, each single-pass scan including the test wafer entering the beam from one side along the second direction and completely exiting the beam from the other side, so as to complete the ion implantation treatment of the test wafer, wherein the second direction is perpendicular to the first direction.

[0011] Optionally, the step of performing multiple single-pass scans of the test wafer at a uniform speed reciprocatingly along the second direction using the ion beam includes: maintaining the beam current of the ion beam stable and unchanged; and moving the test wafer along the second direction to complete multiple single-pass scans of the test wafer.

[0012] Optionally, a plurality of sampling points are symmetrically distributed on the test wafer surface about a theoretical vertical implantation position.

[0013] Optionally, the plurality of sampling points are evenly distributed along the first direction on the surface of the test wafer.

[0014] Optionally, the sampling points include a theoretical vertical implantation position on the test wafer and two edge positions of an ion implantation region of the ion implantation process in the first direction.

[0015] Optionally, in the step of acquiring characteristic values ​​of a plurality of sampling points, the characteristic values ​​include thermal wave values ​​or sheet resistance values ​​of the surface of the test wafer.

[0016] Optionally, the step of obtaining the actual vertical injection position of the ion beam on the test wafer based on the eigenvalue includes: obtaining the position coordinates of multiple sampling points; performing function fitting on the position coordinates of the multiple sampling points and the corresponding eigenvalues ​​to obtain the eigenvalue fitting function; obtaining the position coordinates corresponding to the minimum value of the eigenvalue fitting function as the actual vertical injection position of the ion beam on the test wafer.

[0017] Optionally, the step of correcting the ion injection angle of the ion injection treatment based on the position deviation and the beam divergence angle includes: obtaining a position deviation threshold; when the position deviation is less than the position deviation threshold, evaluating whether the ion injection angle of the ion injection treatment meets the standard and completing the correction of the ion injection angle; when the position deviation is greater than or equal to the position deviation threshold, obtaining a correction angle of the ion injection angle based on the position deviation; and correcting the ion injection angle of the ion injection treatment according to the correction angle.

[0018] Optionally, the step of obtaining a position deviation threshold includes: based on the beam divergence angle, calibrating the correspondence between the position deviation and the ion injection angle deviation; according to the correspondence, obtaining the position deviation corresponding to the angle deviation threshold under the beam divergence angle as the position deviation threshold; in the step of obtaining a correction angle of the ion injection angle based on the position deviation, obtaining the ion injection angle deviation corresponding to the position deviation as the correction angle according to the correspondence.

[0019] Optionally, the step of correcting the ion implantation angle of the ion implantation process based on the position deviation and the beam divergence angle also includes: obtaining the ion implantation angle of the theoretical vertical implantation position as the angle deviation based on the position deviation; and correcting the ion implantation angle of the ion implantation process based on the angle deviation.

[0020] Optionally, the step of performing ion implantation treatment on the test wafer also includes: obtaining the length dimension of the ion implantation area of ​​the test wafer in the first direction; based on the position deviation, obtaining the ion implantation angle of the theoretical vertical implantation position as the angle deviation step includes: combining the length dimension, the beam divergence angle of the ion beam, and the position deviation, and calculating the ion implantation angle of the theoretical vertical implantation position as the angle deviation.

[0021] Optionally, the expression α=dβ / D is used to calculate the ion injection angle of the theoretical vertical injection position as the angle deviation, where α is the ion injection angle of the theoretical vertical injection position, d is the position deviation, β is the beam divergence angle of the ion beam, and D is the length dimension.

[0022] Optionally, based on the angle deviation, the step of correcting the ion injection angle of the ion injection treatment includes: when the angle deviation is less than the angle deviation threshold, evaluating whether the ion injection angle of the ion injection treatment meets the standard, and completing the correction of the ion injection angle; when the angle deviation is greater than or equal to the angle deviation threshold, using the angle deviation as the correction angle; and correcting the ion injection angle of the ion injection treatment according to the correction angle.

[0023] Optionally, the step of correcting the ion implantation angle of the ion implantation process according to the correction angle includes: correcting the position of the test wafer according to the correction angle.

[0024] Optionally, after the position of the test wafer is corrected according to the correction angle, the method further includes: returning to execute the step of providing the test wafer until the ion implantation angle of the ion implantation process is evaluated to be up to standard, thereby completing the correction of the ion implantation angle.

[0025] Optionally, in the step of providing a test wafer, the test wafer is fixed on a wafer chuck; and the step of correcting the position of the test wafer according to the correction angle includes: correcting the wafer chuck according to the correction angle.

[0026] Optionally, the step of correcting the wafer chuck according to the correction angle includes: rotating the wafer chuck by a correction angle with a second direction as the rotation axis, the second direction being perpendicular to the first direction, wherein when the beam divergence angle is a divergence angle, the actual vertical injection position is rotated away from the beam source relative to the theoretical vertical injection position, and when the beam divergence angle is a focusing angle, the actual vertical injection position is rotated closer to the beam source relative to the theoretical vertical injection position.

[0027] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0028] In the method for correcting the ion implantation angle provided in the embodiment of the present invention, an ion implantation treatment is performed on a test wafer, and the ion beam of the ion implantation treatment is a beam current with a preset beam divergence angle, so that the ion implantation angle on the surface of the test wafer gradually changes along a first direction, and a plurality of sampling points are selected along the first direction on the surface of the test wafer, and the actual vertical implantation position of the ion beam on the test wafer is obtained based on the characteristic value, and the position deviation between the actual vertical implantation position and the theoretical vertical implantation position in the first direction is obtained, and the ion implantation angle of the ion implantation treatment is corrected based on the position deviation and the beam divergence angle; in the step of performing ion implantation treatment on the test wafer in the embodiment of the present invention, the ion beam is a beam current with a preset beam divergence angle, and the beam divergence angle is a divergence angle or a focusing angle, so when the ion beam is emitted onto the test wafer, the ion implantation angle of the ion beam is different at different positions of the test wafer, and the farther away from the theoretical vertical implantation position, the larger the ion implantation angle, and the closer to the theoretical vertical implantation position, the larger the ion implantation angle. The smaller the ion implantation angle is, the more sampling points of different ion implantation angles can be obtained on a test wafer. There is no need to use a test wafer for sampling of each different ion implantation angle. That is, a correction of the ion implantation angle can be completed with a test wafer, which is beneficial to reduce the number of test wafers used, thereby helping to reduce the correction cost of the ion implantation angle. At the same time, there is no need to replace the test wafer during a correction process, and there is no need to adjust the injection angle of the ion implantation process, making the correction process simpler and easier to implement. Moreover, sampling points of different ion implantation angles are obtained on a test wafer. Compared with using different test wafers corresponding to different ion implantation angles for correction, this scheme controls the variables of the test wafer, which is beneficial to reducing the variable influence brought by different test wafers themselves, thereby facilitating more accurate acquisition of the position deviation based on the variables of the ion implantation angle, and further facilitating more accurate correction of the ion implantation angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figures 1 to 3 is a step diagram corresponding to each step in an embodiment of a method for correcting an ion implantation angle of the present invention;

[0030] Figure 4 It is a step diagram corresponding to each step in an embodiment of a method for correcting an ion implantation angle of the present invention. DETAILED DESCRIPTION

[0031] At present, the accuracy of evaluation and correction of ion implantation angle needs to be improved. This paper analyzes the reasons why the accuracy of correction of ion implantation angle needs to be improved by combining a correction method of ion implantation angle.

[0032] At present, the commonly used method for correcting the ion implantation angle is the five-point method. The five-point method refers to selecting multiple angle values ​​near the ion implantation angle of 0° (i.e., the vertical implantation position), and then selecting five test wafers to perform ion implantation on the five test wafers at different selected angles. After each ion implantation, the thermal wave value or resistance value on the surface of the corresponding test wafer is measured. Finally, after the ion implantation test of all angles is completed, a relationship diagram of the thermal wave value-injection angle or a relationship diagram of the resistance value-injection angle is drawn, and a quadratic curve fitting is performed based on the relationship diagram to obtain a fitting curve function, and the actual deviation value of the ion implantation angle of the machine is obtained based on the fitting curve function to evaluate the ion implantation angle. However, this correction method requires at least five test wafers each time, which is costly, and the replacement of multiple test wafers in this method is cumbersome and easily leads to more variables causing errors, and the feasibility is poor.

[0033] To solve the above problems, an embodiment of the present invention provides a method for correcting an ion implantation angle, comprising: providing a test wafer; performing ion implantation on the test wafer, wherein the ion beam of the ion implantation is a beam with a preset beam divergence angle, so that the ion implantation angle on the surface of the test wafer gradually changes along a first direction, wherein the beam divergence angle is a divergence angle or a focusing angle, and the first direction is the divergence or focusing direction of the ion beam; obtaining a theoretical vertical implantation position of the ion implantation on the test wafer; selecting a plurality of sampling points along the first direction on the surface of the test wafer; obtaining characteristic values ​​of the plurality of sampling points; obtaining an actual vertical implantation position of the ion beam on the test wafer based on the characteristic values; obtaining a position deviation between the actual vertical implantation position and the theoretical vertical implantation position in the first direction; and correcting the ion implantation angle of the ion implantation based on the position deviation and the beam divergence angle.

[0034] In an embodiment of the present invention, in the step of performing ion implantation on a test wafer, the ion beam is a beam current with a preset beam divergence angle, and the beam divergence angle is a divergence angle or a focusing angle. If the beam divergence angle is a divergence angle, it indicates that the width of the ion beam in the divergence direction gradually increases along the beam direction, that is, the width of the ion beam in the first direction gradually increases. If the beam divergence angle is a focusing angle, it indicates that the width of the ion beam in the focusing direction gradually decreases along the beam direction, that is, the width of the ion beam in the first direction gradually decreases. When the ion beam is emitted onto the test wafer, the ion implantation angle of the ion beam is different at different positions of the test wafer. After obtaining the beam divergence angle and the ion implantation area of ​​the ion implantation treatment, the theoretical vertical implantation position of the ion beam on the test wafer can be calculated under the premise that there is no implantation angle deviation by default. The farther away from the theoretical vertical implantation position, the larger the ion implantation angle, and the closer to the theoretical vertical implantation position, the smaller the ion implantation angle. The invention discloses a method for obtaining sampling points of different ion implantation angles on a test wafer, and a method for obtaining sampling points of different ion implantation angles on a test wafer. The method does not need to use a test wafer for sampling of each different ion implantation angle, that is, a correction of the ion implantation angle can be completed with a test wafer, which is beneficial to reduce the number of test wafers used, thereby helping to reduce the correction cost of the ion implantation angle. At the same time, there is no need to replace the test wafer during a correction process, and there is no need to adjust the injection angle of the ion implantation process, which makes the correction process simpler and easier to implement. Moreover, sampling points of different ion implantation angles are obtained on a test wafer. Compared with using different test wafers corresponding to different ion implantation angles for correction, this scheme controls the variables of the test wafer, which is beneficial to reducing the influence of variables brought by different test wafers themselves, thereby helping to obtain the position deviation more accurately based on the variables of the ion implantation angle, and further helping to correct the ion implantation angle more accurately.

[0035] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and easy to understand, the following is a summary of the present invention. Figures 1 to 3 The specific embodiments of the present invention are described in detail.

[0036] refer to Figure 1 , providing a test wafer 110.

[0037] The test wafer 110 is provided for performing an ion implantation process on the test wafer 110 to evaluate an ion implantation angle.

[0038] Specifically, in the present embodiment, in the step of providing the test wafer 110 , the test wafer 110 is fixed on the wafer chuck 100 .

[0039] The wafer chuck 100 is used to carry the test wafer 110 . Specifically, when the test wafer 110 is fixed on the wafer chuck 100 , the placement position of the test wafer 110 is limited by the wafer chuck 100 .

[0040] In this embodiment, the step of providing the test wafer 110 further includes: obtaining the diameter of the test wafer 110 .

[0041] The diameter of the test wafer 110 is obtained for subsequent calculation of the angle deviation.

[0042] Continue to refer Figure 1 , the test wafer 110 is subjected to ion implantation, wherein the ion beam 200a of the ion implantation is a beam having a preset beam divergence angle β, so that the ion implantation angle α on the surface of the test wafer 110 is along a first direction (such as Figure 1 The beam divergence angle β is a divergence angle or a focusing angle, and the first direction is the divergence or focusing direction of the ion beam.

[0043] The test wafer 110 is subjected to ion implantation to correct the ion implantation angle α of the ion implantation, wherein the beam divergence angle β is a divergence angle or a focusing angle, that is, the ion beam 200 a is a beam that diverges along a first direction or converges along a first direction.

[0044] As an example, in this embodiment, the beam divergence angle is taken as the divergence angle, and the ion beam 200a is a beam with a preset divergence angle as an example for description.

[0045] Specifically, in this embodiment, the ion implantation angle α increases linearly from the center of the ion beam 200 a toward the outside along the first direction.

[0046] In the present embodiment, in the step of performing ion implantation on the test wafer 110, the ion beam 200a is a beam with a preset beam divergence angle β, and the beam divergence angle β is a divergence angle or a focusing angle. If the beam divergence angle β is a divergence angle, it indicates that the width of the ion beam 200a in the divergence direction gradually increases along the beam direction, that is, the width of the ion beam 200a in the first direction gradually increases. If the beam divergence angle β is a focusing angle, it indicates that the width of the ion beam 200a in the focusing direction gradually decreases along the beam direction, that is, the width of the ion beam 200a in the first direction gradually decreases. When the ion beam 200a is emitted onto the test wafer 110, the ion implantation angles of the ion beam 200a are different at different positions of the test wafer 110. After obtaining the beam divergence angle β and the ion implantation area of ​​the ion implantation treatment, the theoretical vertical implantation position of the ion beam 200a on the test wafer 110 can be calculated under the premise that there is no implantation angle deviation. The farther away from the theoretical vertical implantation position, the larger the ion implantation angle α, and the closer to the theoretical vertical implantation position, the smaller the ion implantation angle α. Therefore, sampling points of different ion implantation angles α can be obtained on one test wafer 110. It is not necessary to use one test wafer 110 for each sampling of different ion implantation angles α. That is, one test wafer 110 can be used to complete one correction of the ion implantation angle α, which is beneficial to reduce the number of test wafers 110 used, thereby helping to reduce the correction cost of the ion implantation angle α.

[0047] Specifically, in this embodiment, the beam divergence angle β adjustment device 200 is used to emit an ion beam 200 a to perform ion implantation processing on the test wafer 110 .

[0048] In this embodiment, the beam divergence angle β adjustment device 200 is disposed directly opposite to the wafer chuck 100 .

[0049] In this embodiment, the step of performing ion implantation on the test wafer 110 further includes: obtaining a beam divergence angle β of the ion beam 200 a .

[0050] It should be noted that, in this embodiment, the beam spread angle β of the ion beam 200a is a full-angle beam spread angle.

[0051] The beam divergence angle β of the ion beam 200 a is obtained for subsequent calculation of the position deviation amount and the angle deviation amount.

[0052] In this embodiment, in the step of performing ion implantation on the test wafer 110 , the ion beam 200 a is symmetrically distributed on the plane where the beam divergence angle β is located.

[0053] The ion beam 200a is symmetrically distributed on the plane where the beam divergence angle β is located. Then, in the ion implantation area of ​​the test wafer 110 surface subjected to ion implantation treatment, the ion implantation angle α in the first direction is symmetrical about the center position of the ion implantation area, so that the ion doping in the first direction in the test wafer 110 is evenly distributed from the center position of the ion implantation area to both sides, that is, the ion implantation angle α on the surface of the test wafer 110 is evenly distributed from the center position to both sides, thereby making the detection of the distribution of the ion implantation angle α on the surface of the test wafer 110 easier and more accurate results can be obtained.

[0054] In this embodiment, in the step of performing ion implantation on the test wafer 110 , the ion beam 200 a always completely covers the test wafer 110 in the first direction.

[0055] Specifically, the ion beam 200a always completely covers the side of the test wafer 110 facing the beam in the first direction, and the entire surface of the test wafer 110 is used to detect the ion implantation angle α, so that the detection range is sufficient.

[0056] In this embodiment, the step of performing ion implantation on the test wafer 110 further includes: obtaining the length dimension of the ion implantation region of the test wafer 110 that is subjected to the ion implantation in the first direction.

[0057] The length dimension of the ion implantation region on the test wafer 110 in the first direction is obtained for subsequent calculation of the angle deviation.

[0058] Specifically, in this embodiment, the ion beam 200 a always completely covers the test wafer 110 in the first direction. Therefore, the length dimension of the ion implantation region on the test wafer 110 in the first direction is the diameter of the test wafer 110 .

[0059] In this embodiment, the step of performing ion implantation on the test wafer 110 includes: generating an ion beam 200 a , where the ion beam 200 a is a ribbon beam that diverges or focuses in a first direction.

[0060] The ion beam 200 a is a ribbon beam that diverges or focuses in a first direction. The ion beam 200 a covers the test wafer 110 in the first direction and is used to scan the test wafer 110 .

[0061] Specifically, in this embodiment, the ion beam 200a is used to move along the second direction (such as Figure 1 The test wafer 110 is scanned back and forth multiple times at a uniform speed (as shown in the Y direction), and each single-pass scan includes the test wafer 110 entering the beam from one side along the second direction and completely exiting the beam from the other side to complete the ion implantation process on the test wafer 110, wherein the second direction is perpendicular to the first direction.

[0062] The test wafer 110 is scanned along the second direction using the ion beam 200a so that the test wafer 110 is also covered in the second direction of the ion implantation process after the scanning. In addition, the test wafer 110 is scanned back and forth at a uniform speed multiple times in a single-pass manner along the second direction using the ion beam 200a so that the ion implantation process of the test wafer 110 by the ion beam 200a is more complete.

[0063] In this embodiment, the step of performing multiple single-pass scans of the test wafer 110 in a uniform reciprocating manner along the second direction using the ion beam 200a includes: maintaining the beam current of the ion beam 200a stable and unchanged; and moving the test wafer 110 along the second direction to complete multiple single-pass scans of the test wafer 110.

[0064] The beam current of the ion beam 200a is maintained stable and unchanged, and the test wafer 110 is moved to complete the scanning of the test wafer 110. The movement of the wafer chuck 100 is relatively simple, so that the scanning of the test wafer 110 is easy to achieve. Maintaining the beam current of the ion beam 200a is stable and unchanged, which is beneficial to avoid the shaking of the ion beam 200a and to make the ion implantation angle α emitted on the test wafer 110 more stable, thereby helping to ensure the accuracy of ion implantation angle detection.

[0065] Continue to refer Figure 1 , obtain the theoretical vertical implantation position C of the ion implantation process on the test wafer 110.

[0066] The theoretical vertical implantation position is used for subsequent evaluation and comparison with the actual vertical implantation position of the ion beam 200 a on the test wafer 110 , so as to correct the ion implantation angle α of the ion implantation process.

[0067] In this embodiment, in the step of obtaining the theoretical vertical implantation position C of the ion implantation process on the test wafer 110 , the theoretical vertical implantation position C coincides with the center of the test wafer 110 .

[0068] Accordingly, in this embodiment, in the step of obtaining the theoretical vertical implantation position C of the ion implantation process on the test wafer 110 , the theoretical vertical implantation position C is the middle position of the ion implantation region.

[0069] The theoretical vertical injection position C coincides with the center of the test wafer 110 , which is conducive to simplifying the acquisition of the theoretical vertical injection position C, thereby facilitating the subsequent evaluation and comparison with the actual vertical injection position of the ion beam 200 a on the test wafer 110 .

[0070] refer to Figure 2 , on the surface of the test wafer 110 , multiple sampling points 100 a are selected along a first direction.

[0071] On the surface of the test wafer 110 , multiple sampling points 100 a are selected along the first direction, that is, each sampling point 100 a corresponds to a different ion implantation angle α, and subsequently detection is performed at the multiple sampling points 100 a to obtain the actual vertical implantation position of the ion implantation process on the test wafer 110 .

[0072] In this embodiment, a plurality of sampling points 100 a are symmetrically distributed about a theoretical vertical implantation position C on the surface of the test wafer 110 .

[0073] In this embodiment, the beam divergence angle β of the ion beam 200a in the first direction is symmetrically distributed about the theoretical vertical injection position C in the first direction, and multiple sampling points 100a are symmetrically distributed about the theoretical vertical injection position C on the surface of the test wafer 110. Then, the ion injection angles α corresponding to the multiple sampling points 100a are symmetrical about the theoretical vertical injection position C on the surface of the test wafer 110, which is conducive to the convenience of subsequent sampling and detection of the sampling points 100a.

[0074] Specifically, in this embodiment, the plurality of sampling points 100 a are symmetrically distributed on the surface of the test wafer 110 about the center of the test wafer 110 .

[0075] In this embodiment, the plurality of sampling points 100 a are evenly distributed along a first direction on the surface of the test wafer 110 .

[0076] Subsequently, the characteristic values ​​of the multiple sampling points 100 a need to be fitted. The multiple sampling points 100 a are evenly distributed along the first direction on the surface of the test wafer 110 , which is beneficial to the subsequent fitting steps and to ensuring the accuracy of the subsequent fitting.

[0077] In this embodiment, the sampling points 100 a include a theoretical vertical implantation position C on the test wafer 110 and two edge positions of the ion implantation region in the first direction.

[0078] The theoretical vertical injection position C on the test wafer 110 is the minimum point of the ion injection angle α on the test wafer 110 theoretically considered during the evaluation. The two edge positions of the ion injection area in the first direction on the test wafer 110 are the maximum points of the ion injection angle α on the test wafer 110 theoretically considered during the evaluation. Therefore, the sampling point 100a includes the theoretical vertical injection position C on the test wafer 110 and the two edge positions of the ion injection area in the first direction, and includes the theoretical key peak point of the ion injection angle α, which is conducive to a more accurate evaluation of the distribution of the ion injection angle α on the surface of the test wafer 110.

[0079] As an example, in this embodiment, the ion implantation process fully covers the test wafer 110, and the theoretical vertical implantation position C coincides with the center of the test wafer 110. The sampling point 100a includes the center of the test wafer 110 and two edge points of the test wafer 110 along the first direction.

[0080] Continue to refer Figure 2 , obtain the characteristic values ​​of multiple sampling points 100a.

[0081] The characteristic value represents the lattice damage of the ion implantation treatment on the surface of the test wafer 110 , and the characteristic values ​​of multiple sampling points 100 a are acquired to obtain the distribution of the ion implantation angle α on the surface of the test wafer 110 .

[0082] In this embodiment, in the step of acquiring characteristic values ​​of a plurality of sampling points 100 a , the characteristic values ​​include a thermal wave value (TW) or a sheet resistance value (Rs) of the surface of the test wafer 110 .

[0083] The thermal wave value is the thermal wave value (TW). In this embodiment, a thermal wave system is used to obtain the thermal wave value of the sampling point 100a. Specifically, the thermal wave system measures the change in reflectivity of the two laser beams focused on the same point on the test wafer 110 on the surface of the test wafer 110 through a thermal wave detector to calculate the injection concentration of the impurity particles. In this system, a laser beam generates a heating wave through an argon laser to increase the surface temperature of the test wafer 110. The heating of the test wafer 110 will cause the reflection coefficient of the other helium-neon laser to change. This change is proportional to the number of crystal defect points generated by the injection of impurity particles into the test wafer 110, that is, the thermal wave value is proportional to the number of crystal defect points generated by the injection of impurity particles into the test wafer 110.

[0084] In other embodiments, the four-probe method can also be used to measure the square resistance value. The square resistance value can be understood as the resistance between the two ends of the square film on the test wafer, which is related to the resistivity and thickness of the film and has nothing to do with the size of the square thin layer. The four-probe method contacts the test wafer with four probes placed equidistantly in a straight line in turn, applies a known current between the two outer probes, and measures the potential difference between the two inner probes at the same time, thereby obtaining the square resistance value.

[0085] Specifically, in this embodiment, the closer the surface of the test wafer 110 is to the center of the beam, the smaller the ion injection angle α of the ion injection treatment, the more obvious the channeling effect, the fewer collisions between the beam and the lattice, the less lattice damage, and the lower the thermal wave value; the closer to the edge of the beam, the larger the ion injection angle α of the ion injection treatment, the less channeling effect, the more collisions between the beam and the lattice, the more lattice damage, and the higher the thermal wave value; therefore, the lattice damage of the ion injection treatment can be characterized by the thermal wave value of the sampling point 100a, thereby characterizing the distribution of the ion injection angle α.

[0086] In this embodiment, a thermal wave detector is used for sampling. The multi-point sampling and diameter direction sampling functions of the thermal wave detector are conducive to significantly increasing the sampling points 100a, thereby improving the subsequent fitting accuracy of the characteristic values ​​of the multiple sampling points 100a.

[0087] In this embodiment, the actual vertical implantation position P of the ion beam 200 a on the test wafer 110 is acquired based on the characteristic value.

[0088] The actual vertical injection position P of the ion beam 200a on the test wafer 110 is the position where the degree of lattice damage on the surface of the test wafer 110 is the maximum or the position where the defect density is the maximum. Specifically, in the ion injection process, the larger the ion injection angle α, the smaller the channeling effect, the more collisions between the beam and the lattice, the greater the lattice damage or the greater the defect density; the smaller the ion injection angle α, the more obvious the channeling effect, the fewer collisions between the beam and the lattice, the smaller the lattice damage or the smaller the defect density; in this embodiment, the ion injection angle α gradually increases outward from the actual vertical injection position P; the actual vertical injection position P is the point where the ion injection angle α on the surface of the test wafer 110 is 0°.

[0089] In this embodiment, the step of acquiring the actual vertical implantation position P of the ion beam 200 a on the test wafer 110 based on the characteristic value includes: acquiring the position coordinates of a plurality of sampling points 100 a .

[0090] As an example, in this embodiment, the theoretical vertical implantation position C on the test wafer 110 is taken as the origin, and the position coordinates of the plurality of sampling points 100 a based on the origin are obtained.

[0091] In other embodiments, any other point may be used as the origin to obtain position coordinates of multiple sampling points based on the origin.

[0092] If the position of the wafer chuck 100 is accurate, the ion beam 200a should be perpendicular to the surface of the test wafer 110 at the theoretical vertical injection position C, that is, the theoretical vertical injection position C on the test wafer 110 is the point where the theoretical ion injection angle α is 0°. Therefore, taking the theoretical vertical injection position C on the test wafer 110 as the origin, the position coordinates of multiple sampling points 100a based on the origin are obtained.

[0093] Specifically, in this embodiment, the distance between the sampling point 100a and the origin is used as the coordinate value, one side of the origin is positive, and the other side is negative, so as to obtain the position coordinates of the plurality of sampling points 100a based on the origin.

[0094] As an example, in this embodiment, the diameter of the test wafer 110 is 300 mm, and five sampling points 100 a are selected on the surface of the test wafer 110 . The position coordinates of the five sampling points 100 a are respectively -150, -75, 0, 75, and 150.

[0095] In this embodiment, function fitting is performed on the position coordinates of the plurality of sampling points 100 a and the corresponding eigenvalues ​​to obtain an eigenvalue fitting function.

[0096] The eigenvalue fitting function characterizes the ion doping condition on the entire surface of the test wafer 110 , thereby characterizing the distribution of the ion implantation angle α on the entire surface of the test wafer 110 .

[0097] Specifically, in this embodiment, function fitting is performed on the position coordinates of the plurality of sampling points 100 a and the corresponding thermal wave values ​​to obtain a characteristic value fitting function (ie, a thermal wave distribution diagram).

[0098] As an example, in this embodiment, if Figure 2 The characteristic value fitting function A is shown, wherein the abscissa is the position coordinate of the sampling point 100 a and the ordinate is the thermal wave value.

[0099] In this embodiment, the position deviation and the angle deviation are subsequently calculated based on the thermal wave distribution diagram, which is highly intuitive and is conducive to more accurately obtaining the actual vertical injection position P to calculate the position deviation and the angle deviation.

[0100] In this embodiment, the position coordinate corresponding to the minimum value of the eigenvalue fitting function is obtained as the actual vertical implantation position P on the surface of the test wafer 110 .

[0101] From the above, it can be seen that the thermal wave value on the surface of the test wafer 110 is the smallest when the ion implantation angle α is the smallest (i.e., 0°). Therefore, the position coordinate corresponding to the minimum value of the eigenvalue fitting function is the smallest ion implantation angle α (i.e., 0°), which is also the actual vertical implantation position P.

[0102] As an example, in this embodiment, if Figure 2 As shown, the position coordinate -10 corresponding to the minimum value of the eigenvalue fitting function A is the actual vertical injection position P.

[0103] refer to Figure 3 , obtain the position deviation d between the actual vertical injection position P and the theoretical vertical injection position C in the first direction.

[0104] The theoretical vertical injection position C is the point where the theoretical ion injection angle α is the smallest (i.e., 0°), and the actual vertical injection position P is the point where the ion injection angle α corresponding to the actual ion beam 200a is the smallest (i.e., 0°). Therefore, the position deviation d between the theoretical vertical injection position C and the actual vertical injection position P on the test wafer 110 is the deviation caused by the ion injection process of the actual ion beam 200a on the test wafer 110.

[0105] refer to Figure 4 , based on the position deviation d and the beam divergence angle β, the ion implantation angle α of the ion implantation process is corrected.

[0106] In the present embodiment, during a correction process, there is no need to replace the test wafer 110, and there is no need to adjust the injection angle of the ion implantation process, which makes the correction process simpler and easier to implement. Moreover, sampling points 100a of different ion implantation angles α are obtained on a test wafer 110. Compared with using different test wafers corresponding to different ion implantation angles for correction, the present scheme controls the variables of the test wafer 110, which is beneficial to reducing the influence of variables brought by different test wafers 110 themselves, thereby facilitating more accurate acquisition of position deviation based on the variables of the ion implantation angle α, and further facilitating more accurate correction of the ion implantation angle α.

[0107] In this embodiment, the step of correcting the ion implantation angle α of the ion implantation process based on the position deviation d and the beam divergence angle β includes: obtaining the ion implantation angle α of the theoretical vertical implantation position C as the angle deviation based on the position deviation d.

[0108] Theoretically, the ion implantation angle α at the theoretical vertical implantation position C should be 0°. Therefore, in practice, the ion implantation angle α at the theoretical vertical implantation position C is the angle deviation of the ion implantation process.

[0109] In this embodiment, the step of obtaining the ion injection angle α of the theoretical vertical injection position C as the angle deviation based on the position deviation d includes: combining the length dimension, the beam divergence angle β of the ion beam 200a, and the position deviation d, and calculating the ion injection angle α of the theoretical vertical injection position C as the angle deviation.

[0110] Specifically, in this embodiment, the expression α=dβ / D is used to calculate the ion injection angle of the theoretical vertical injection position C as the angle deviation, where α is the ion injection angle of the theoretical vertical injection position, d is the position deviation, β is the beam divergence angle of the ion beam, and D is the length dimension.

[0111] In this embodiment, the length dimension is the diameter of the test wafer 110 .

[0112] As an example, in this embodiment, the beam divergence angle β of the ion beam 200a is 1°, the diameter D of the test wafer 110 is 300 mm, and the position deviation d is 10 mm. Then, the ion implantation angle α of the theoretical vertical implantation position C on the surface of the test wafer 110 is calculated to be 0.033°.

[0113] Accordingly, in this embodiment, the ion implantation angle of the ion implantation process is corrected based on the angle deviation.

[0114] Specifically, in this embodiment, the step of correcting the ion implantation angle of the ion implantation process based on the angle deviation includes: when the angle deviation is less than the angle deviation threshold, completing the correction of the ion implantation angle α.

[0115] When the angle deviation is less than the angle deviation threshold, it indicates that the angle deviation is small and will not have a substantial impact on the ion implantation process, so the ion implantation angle α of the ion implantation process meets the standard.

[0116] Specifically, in the present embodiment, the ion implantation angle α of the ion implantation process meets the standard, that is, the position of the test wafer 110 is relatively accurate, that is, the wafer chuck 100 is relatively accurate.

[0117] In this embodiment, when the angle deviation is greater than or equal to the angle deviation threshold, the angle deviation is used as the correction angle.

[0118] When the angle deviation is greater than or equal to the angle deviation threshold, it indicates that the angle deviation is large, which will have a substantial impact on the ion implantation process, and therefore the ion implantation angle α of the ion implantation process does not meet the standard.

[0119] Specifically, in the present embodiment, the ion implantation angle α of the ion implantation process does not meet the standard, that is, the position deviation of the test wafer 110 is large, that is, the error of the wafer chuck 100 is large.

[0120] In this embodiment, the ion implantation angle α of the ion implantation process is corrected according to the correction angle.

[0121] In other embodiments, the ion implantation angle α of the ion implantation process may be corrected only according to the position deviation amount d.

[0122] Specifically, in other embodiments, the step of correcting the ion implantation angle α of the ion implantation process based on the position deviation d and the beam divergence angle β includes: acquiring a position deviation threshold.

[0123] The position deviation threshold is used to evaluate whether the correction of the ion implantation angle α is completed.

[0124] In other embodiments, the step of obtaining the position deviation threshold includes: based on the beam divergence angle β, calibrating the corresponding relationship between the position deviation and the ion implantation angle α deviation.

[0125] The corresponding relationship between the calibration position deviation and the ion implantation angle α deviation is used to obtain the position deviation threshold corresponding to different beam divergence angles β.

[0126] Correspondingly, in other embodiments, according to the corresponding relationship, the position deviation corresponding to the angle deviation threshold under the beam divergence angle β is obtained as the position deviation threshold.

[0127] In other embodiments, when the position deviation d is less than the position deviation threshold, it is evaluated that the ion implantation angle α of the ion implantation process meets the standard, and the correction of the ion implantation angle α is completed.

[0128] When the position deviation d is less than the position deviation threshold, it indicates that the position deviation d is small and will not have a substantial impact on the ion implantation process, so the ion implantation angle α of the ion implantation process meets the standard.

[0129] In other embodiments, when the position deviation d is greater than or equal to the position deviation threshold, a correction angle of the ion implantation angle α is obtained based on the position deviation d.

[0130] When the position deviation d is greater than or equal to the position deviation threshold, it indicates that the position deviation d is large, which will have a substantial impact on the ion implantation process, and therefore the ion implantation angle α of the ion implantation process does not meet the standard.

[0131] Specifically, the detailed steps of obtaining the correction angle of the ion implantation angle α based on the position deviation d refer to the aforementioned embodiment.

[0132] Correspondingly, in other embodiments, the ion implantation angle α of the ion implantation process is also corrected according to the correction angle.

[0133] In this embodiment, the step of correcting the ion implantation angle α of the ion implantation process according to the correction angle includes: correcting the position of the test wafer 110 according to the correction angle.

[0134] The position of the test wafer 110 is corrected according to the correction angle so that the position deviation amount d is gradually reduced.

[0135] In this embodiment, the step of correcting the position of the test wafer 110 according to the correction angle includes: correcting the wafer chuck 100 according to the correction angle.

[0136] The wafer chuck 100 is used to carry the test wafer 110. Specifically, when the test wafer 110 is fixed on the wafer chuck 100, the position of the test wafer 110 is limited by the wafer chuck 100. The wafer chuck 100 is corrected according to the correction angle to adjust the position of the test wafer 110, thereby adjusting the relative angle between the surface of the test wafer 110 and the ion beam 200a, that is, correcting the ion implantation angle α.

[0137] Moreover, calibrating the wafer chuck 100 according to the correction angle is more intuitive and easy to operate.

[0138] Specifically, in this embodiment, the step of correcting the wafer chuck 100 according to the correction angle includes: rotating the wafer chuck 100 by a correction angle with the second direction as the rotation axis, the second direction being perpendicular to the first direction, wherein, when the beam divergence angle β is a divergence angle, the actual vertical injection position P is rotated away from the beam source relative to the theoretical vertical injection position C, and when the beam divergence angle β is a focusing angle, the actual vertical injection position P is rotated closer to the beam source relative to the theoretical vertical injection position C.

[0139] It should be noted that the beam source refers to the source of the ion beam 200a generated by the ion implantation process, such as Figure 4 The device 200 for adjusting the middle beam divergence angle β.

[0140] Theoretically, the ion implantation angle α of the theoretical vertical implantation position C on the surface of the test wafer 110 should be 0°. The calculated ion implantation angle α (i.e., the angle deviation) of the theoretical vertical implantation position C on the surface of the test wafer 110 is the deviation angle of the ion implantation process, i.e., the deviation angle of the position of the test wafer 110, i.e., the deviation angle of the wafer chuck 100. Therefore, rotating the wafer chuck 100 by the correction angle (angle deviation) is helpful in eliminating the error caused by the wafer chuck 100 in the ion implantation process.

[0141] As an example, Figure 4 As shown, in this embodiment, the beam divergence angle β is a divergence angle. When the actual vertical injection position P is above the theoretical vertical injection position C along the first direction, the wafer chuck 100 is rotated clockwise (such as Figure 4 When the actual vertical injection position P is below the theoretical vertical injection position C along the first direction, the wafer chuck 100 is rotated counterclockwise.

[0142] In this embodiment, after the position of the test wafer 110 is corrected according to the correction angle, the step of returning to the step of providing the test wafer 110 is further included, until the ion implantation angle α of the ion implantation process is evaluated to meet the standard, and the correction of the ion implantation angle α is completed.

[0143] Specifically, after the position of the test wafer 110 is corrected according to the correction angle, the step of providing the test wafer 110 is returned to perform correction of the ion implantation angle α using another test wafer 110 , and the process is repeated multiple times until the ion implantation angle α of the ion implantation process is evaluated to meet the standard.

[0144] In this embodiment, when it is evaluated that the ion implantation angle α of the ion implantation process meets the standard, the correction of the ion implantation angle α is completed.

[0145] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for correcting an ion implantation angle, characterized in that: include: Provide test wafers; Performing ion implantation on the test wafer, wherein the ion beam of the ion implantation is a beam current with a preset beam divergence angle, so that the ion implantation angle on the surface of the test wafer gradually changes along a first direction, wherein the beam divergence angle is a divergence angle or a focusing angle, and the first direction is a divergence or focusing direction of the ion beam; Obtaining a theoretical vertical implantation position of the ion implantation process on a test wafer; On the surface of the test wafer, selecting a plurality of sampling points along the first direction; Acquiring characteristic values ​​of a plurality of the sampling points, wherein the characteristic values ​​include a thermal wave value or a sheet resistance value on the surface of the test wafer; Acquire the actual vertical implantation position of the ion beam on the test wafer based on the characteristic value; Obtaining a position deviation between the actual vertical injection position and the theoretical vertical injection position in the first direction; An ion implantation angle of the ion implantation process is corrected based on the positional deviation and the beam divergence angle.

2. The correction method according to claim 1, characterized in that: In the step of performing ion implantation on the test wafer, the ion beam is symmetrically distributed on a plane where the beam divergence angle is located.

3. The correction method according to claim 1, characterized in that: In the step of performing ion implantation on the test wafer, the ion beam always completely covers the test wafer in the first direction.

4. The correction method according to claim 1, characterized in that: In the step of obtaining a theoretical vertical implantation position of the ion implantation process on the test wafer, the theoretical vertical implantation position coincides with the center of the test wafer.

5. The correction method according to claim 3, characterized in that: The step of performing ion implantation on the test wafer includes: generating the ion beam, wherein the ion beam is a ribbon beam that diverges or focuses in the first direction; The ion beam is used to perform multiple single-pass scans on the test wafer in a uniform reciprocating manner along a second direction, each single-pass scan includes the test wafer entering the beam from one side along the second direction and completely exiting the beam from the other side, so as to complete the ion implantation process on the test wafer, wherein the second direction is perpendicular to the first direction.

6. The correction method according to claim 5, characterized in that: The step of performing a plurality of single-pass scannings of the test wafer in a uniform reciprocating manner along the second direction using the ion beam comprises: maintaining the beam current of the ion beam stable and unchanged; The test wafer is moved along the second direction to complete multiple single-pass scans of the test wafer.

7. The correction method according to claim 1, characterized in that: The plurality of sampling points are symmetrically distributed on the surface of the test wafer about the theoretical vertical implantation position.

8. The correction method according to claim 1, characterized in that: The plurality of sampling points are evenly distributed on the surface of the test wafer along the first direction.

9. The correction method according to claim 1, characterized in that: The sampling points include the theoretical vertical implantation position on the test wafer and two edge positions of the ion implantation region of the ion implantation process in the first direction.

10. The correction method according to claim 1, characterized in that: The step of obtaining the actual vertical implantation position of the ion beam on the test wafer based on the characteristic value comprises: obtaining the position coordinates of a plurality of the sampling points; Performing function fitting on the position coordinates of the plurality of sampling points and the corresponding eigenvalues ​​to obtain an eigenvalue fitting function; The position coordinates corresponding to the minimum value of the eigenvalue fitting function are obtained as the actual vertical implantation position of the ion beam on the test wafer.

11. The correction method according to claim 1, characterized in that: The step of correcting the ion implantation angle of the ion implantation process based on the position deviation and the beam divergence angle includes: obtaining a position deviation threshold; When the position deviation is less than the position deviation threshold, evaluating whether the ion implantation angle of the ion implantation process meets the standard, and completing the correction of the ion implantation angle; When the position deviation is greater than or equal to a position deviation threshold, obtaining a correction angle of the ion implantation angle based on the position deviation; An ion implantation angle of the ion implantation process is corrected according to the correction angle.

12. The correction method according to claim 11, characterized in that: The step of obtaining the position deviation threshold comprises: based on the beam divergence angle, calibrating the corresponding relationship between the position deviation and the ion implantation angle deviation; According to the corresponding relationship, a position deviation corresponding to the angle deviation threshold under the beam divergence angle is obtained as the position deviation threshold; In the step of obtaining a correction angle of the ion implantation angle based on the position deviation, the ion implantation angle deviation corresponding to the position deviation is obtained as the correction angle according to the corresponding relationship.

13. The correction method according to claim 1, characterized in that: The step of correcting the ion implantation angle of the ion implantation process based on the position deviation and the beam divergence angle further includes: obtaining the ion implantation angle of the theoretical vertical implantation position as the angle deviation based on the position deviation; Based on the angle deviation, an ion implantation angle of the ion implantation process is corrected.

14. The correction method according to claim 13, characterized in that: The step of performing ion implantation on the test wafer further includes: obtaining the length dimension of the ion implantation region of the test wafer in the first direction; Based on the position deviation, the step of obtaining the ion injection angle of the theoretical vertical injection position as the angle deviation includes: combining the length dimension, the beam divergence angle of the ion beam, and the position deviation to calculate the ion injection angle of the theoretical vertical injection position as the angle deviation.

15. The correction method according to claim 14, characterized in that: The ion injection angle of the theoretical vertical injection position is calculated using the expression α=dβ / D as the angle deviation, wherein α is the ion injection angle of the theoretical vertical injection position, d is the position deviation, β is the beam divergence angle of the ion beam, and D is the length dimension.

16. The correction method according to claim 13, characterized in that: The step of correcting the ion implantation angle of the ion implantation process based on the angle deviation comprises: when the angle deviation is less than an angle deviation threshold, evaluating whether the ion implantation angle of the ion implantation process meets the standard, and completing the correction of the ion implantation angle; When the angle deviation is greater than or equal to the angle deviation threshold, taking the angle deviation as the correction angle; An ion implantation angle of the ion implantation process is corrected according to the correction angle.

17. The correction method according to claim 11 or 16, characterized in that: The step of correcting the ion implantation angle of the ion implantation process according to the correction angle includes: correcting the position of the test wafer according to the correction angle.

18. The correction method according to claim 17, characterized in that: After the position of the test wafer is corrected according to the correction angle, the method further includes: returning to execute the step of providing the test wafer until the ion implantation angle of the ion implantation process is evaluated to be up to standard, and the correction of the ion implantation angle is completed.

19. The correction method according to claim 17, characterized in that: In the step of providing the test wafer, the test wafer is fixed on a wafer chuck; The step of correcting the position of the test wafer according to the correction angle includes: correcting the wafer chuck according to the correction angle.

20. The correction method according to claim 19, characterized in that: The step of correcting the wafer chuck according to the correction angle includes: rotating the wafer chuck by the correction angle with a second direction as the rotation axis, the second direction being perpendicular to the first direction, wherein, when the beam divergence angle is a divergence angle, the actual vertical injection position is rotated farther away from the beam source relative to the theoretical vertical injection position, and when the beam divergence angle is a focusing angle, the actual vertical injection position is rotated closer to the beam source relative to the theoretical vertical injection position.

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