Method for improving wafer ion implantation uniformity

Abstract

The present invention provides a method for improving the uniformity of wafer ion implantation. The method comprises: adjusting the current of the first coil group, obtaining the current values ​​of multiple groups of first coil groups and the corresponding dose rates of ribbon ion beams to obtain a first relationship curve; adjusting the current of the second coil group, obtaining the current values ​​of multiple groups of second coil groups and the corresponding dose rates of ribbon ion beams to obtain a second relationship curve; obtaining the first current value range of the first coil group corresponding to the low value range of the dose rate of the first relationship curve, and obtaining the second current value range of the second coil group corresponding to the low value range of the dose rate of the second relationship curve; performing a combined test on the current values ​​within the first current value range and the current values ​​within the second current value range to obtain the lowest dose rate, and setting the current parameters of the first and second coil groups with the current value corresponding to the lowest dose rate. The dose rate of the ribbon ion beam obtained in this way is small, which helps to improve the uniformity of wafer ion implantation.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for improving wafer ion implantation uniformity. Background Art

[0002] At present, in the manufacturing process of semiconductor devices, ion implantation machines are usually used to implant ions into wafers. However, in actual ion implantation, the ion implantation uniformity on the wafer is poor, resulting in different voltage compensation (offset) of devices at different positions in the wafer, poor consistency of devices in the wafer, and small voltage compensation margin of the product, which often leads to voltage compensation failure. Summary of the invention

[0003] One of the purposes of the present invention is to improve the uniformity of wafer ion implantation.

[0004] In order to achieve the above-mentioned object, the present invention provides a method for improving the uniformity of wafer ion implantation. The wafer is implanted with ions using a ribbon ion beam generated by an ion implanter, the ion implanter includes a first coil group and a second coil group, the first coil group is used to adjust and control the width, height and current of the ribbon ion beam, the second coil group is used to adjust and control the height and current of the ribbon ion beam, the dose rate of the ribbon ion beam is related to the current and height of the ribbon ion beam, and the method for improving the uniformity of wafer ion implantation includes:

[0005] Adjusting the current of the first coil group to obtain the current values ​​of multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a first relationship curve according to the current values ​​of the multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, wherein the first range in the first relationship curve is a low value range of the dose rate;

[0006] Adjusting the current of the second coil group to obtain the current values ​​of multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a second relationship curve according to the current values ​​of the multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, wherein the second range in the second relationship curve is a low value range of the dose rate;

[0007] obtaining a first current value range of the first coil group corresponding to the first range based on the first relationship curve, and obtaining a second current value range of the second coil group corresponding to the second range based on the second relationship curve; and

[0008] The current values ​​within the first current value range and the current values ​​within the second current value range are combined to test the dose rate of the ribbon ion beam and obtain the minimum dose rate of the ribbon ion beam, and the current value of the first coil group corresponding to the minimum dose rate is used as the current parameter of the first coil group, and the current value of the second coil group corresponding to the minimum dose rate is used as the current parameter of the second coil group.

[0009] Optionally, the first range only includes the lowest dose rate of the first relationship curve, and the second range only includes the lowest dose rate of the second relationship curve; the current value of the first coil group corresponding to the lowest dose rate in the first relationship curve is confirmed as the current parameter of the first coil group; and the current value of the second coil group corresponding to the lowest dose rate in the second relationship curve is confirmed as the current parameter of the second coil group.

[0010] Optionally, the lowest dose rate of the first relationship curve is used as the lower limit of the first range, and the lowest dose rate of the first relationship curve plus a set tolerance is used as the upper limit of the first range; the lowest dose rate of the second relationship curve is used as the upper limit of the second range, and the lowest dose rate of the second relationship curve plus a set tolerance is used as the upper limit of the second range.

[0011] Optionally, in the step of adjusting the current of the first coil group, the current of the second coil group is set to 0.

[0012] Optionally, when the current of the first coil group is within a set current range, the width of the ribbon ion beam is greater than or equal to the diameter of the wafer; in the step of adjusting the current of the first coil group, the current of the first coil group is adjusted within the set current range.

[0013] Optionally, the dose rate of the ribbon ion beam is Dose rate, Dose rate=Beam current / Beam Height, wherein Beam current is the current of the ribbon ion beam, and Beam Height is the height of the ribbon ion beam.

[0014] Optionally, in the step of adjusting the current of the first coil group, the current and height of the ribbon ion beam corresponding to the current value of each first coil group are recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each first coil group is calculated based on the current and height of the ribbon ion beam; in the step of adjusting the current of the second coil group, the current and height of the ribbon ion beam corresponding to the current value of each second coil group are recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each second coil group is calculated based on the current and height of the ribbon ion beam.

[0015] Optionally, the current of the first coil group is adjusted within a range of -12A to +12A.

[0016] Optionally, the current of the second coil group is adjusted within a range of -90A to +90A.

[0017] Optionally, the ribbon ion beam passes through the first coil group and the second coil group in sequence and then irradiates the wafer.

[0018] In the method for improving the uniformity of wafer ion implantation provided by the present invention, the dose rate of the ribbon ion beam corresponding to the current value of each first coil group is obtained by adjusting the current of the first coil group, and a first relationship curve is obtained according to the current values ​​of multiple groups of first coil groups and the dose rate of the ribbon ion beam. The dose rate of the ribbon ion beam corresponding to the current value of each second coil group is obtained by adjusting the current of the second coil group, and a second relationship curve is obtained according to the current values ​​of multiple groups of second coil groups and the dose rate of the ribbon ion beam. Then, a first current value range of the first coil group corresponding to the low value range of the dose rate in the first relationship curve is obtained, and a second current value range of the second coil group corresponding to the low value range of the dose rate in the second relationship curve is obtained. The current within the first current value range is calculated. The dose rate of the ribbon ion beam is tested by combining the current value within the range of the first current value and the second current value to obtain the minimum dose rate of the ribbon ion beam, the current value of the first coil group corresponding to the minimum dose rate is used as the current parameter of the first coil group, and the current value of the second coil group corresponding to the minimum dose rate is used as the current parameter of the second coil group. The unexpected effect is that the dose rate of the obtained ribbon ion beam is small, or even minimum, so that the contact area between the ribbon ion beam and the wafer is relatively large, which helps to improve the uniformity of wafer ion implantation, improve the performance of device voltage offset in the wafer, improve the problem of frequent voltage offset failure of devices in the wafer, improve the consistency of device performance in the wafer, and less damage to the wafer lattice. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the distribution of ribbon ion beam.

[0020] Figure 2 Schematic diagram of the profiler detecting ion beam current.

[0021] Figure 3 A schematic diagram of the process of ion implantation on a wafer.

[0022] Figure 4 Schematic diagram of the distribution of devices with voltage offset failure in a wafer.

[0023] Figure 5 The figure shows the voltage offset waveforms of multiple devices on a wafer.

[0024] Figure 6 A schematic flow chart of a method for improving wafer ion implantation uniformity provided by an embodiment of the present invention.

[0025] Figure 7 A relationship diagram of the current value of the first coil group and the height, current and dose rate of the ribbon ion beam provided in one embodiment of the present invention.

[0026] Figure 8 A relationship diagram of the current value of the second coil group and the height, current and dose rate of the ribbon ion beam provided in one embodiment of the present invention.

[0027] Fig. 9 FIG. 4 is a schematic diagram of a ribbon ion beam with a dose rate of 0.2 according to an embodiment of the present invention.

[0028] Fig.10 FIG. 4 is a schematic diagram of a ribbon ion beam with a dose rate of 0.4 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Figure 1 Schematic diagram of the distribution of ribbon ion beam. Figure 1 As shown in FIG. 1 , there may be some small areas ( Figure 1 The uniformity deviation of the smaller area is smaller than the sampling pitch of the machine detection, for example, less than 3mm. After ion implantation, there are differences between devices or chips.

[0030] Figure 2 The following is a schematic diagram of the profiler detecting the ion beam current. Figure 2 As shown, in an ion implantation machine, such as a ribbon beam implanter, a profiler moves back and forth to detect the current of a ribbon ion beam on the surface of a wafer 10. For example, a point is sampled every 3 mm and a current value is obtained using a Faraday cup. A total of 101 points are sampled for a wafer with a diameter of 300 mm. The beam current uniformity (beam U%) is calculated based on the current values ​​of the 101 points sampled in the wafer. Beam U% = Stdev / mean, where Stdev is the standard deviation of the 101 current values ​​and mean is the mean of the 101 current values. In actual tests, it was found that because the device size is much smaller than the machine sampling interval of 3 mm, and there are some tiny areas with poor uniformity in the ribbon ion beam, but the machine did not sample them, there is a problem that the beam current uniformity obtained by the test is good but the uniformity of the actual tiny area is poor, that is, the current of the actual ribbon ion beam is poorly distributed on the wafer. When the ribbon ion beam is used to perform ion implantation on the wafer, the ion implantation uniformity of the wafer is poor.

[0031] Figure 3 This is a schematic diagram of the process of ion implantation on a wafer. Figure 3 As shown, the wafer 10 is ion implanted in four steps, wherein after one step of ion implantation is completed, the wafer 10 is rotated 90° for the next step of ion implantation. After the wafer ion implantation is completed, device voltage offset detection is performed. Figure 5 The voltage offset waveform of multiple devices (or chips) on a wafer is shown below. Figure 5 The horizontal axis is the number of different devices, and the vertical axis is the voltage offset value of the device. Figure 5 As shown in FIG. 1 , due to the poor uniformity of ion implantation in the wafer, the voltage offset uniformity of the devices in the wafer is poor, and the consistency of the performance of the devices in the wafer is poor. The voltage offset of some devices in the wafer will exceed the upper limit of the voltage offset specification, and as shown in FIG. Figure 4 As shown in Figure 1, devices with voltage offset exceeding the specification often have an X-shaped distribution on the wafer.

[0032] In order to solve the above-mentioned problems of poor uniformity of wafer ion implantation and poor consistency of device performance in the wafer, the ion implantation machine and ion implantation process were studied, and it was found that the voltage offset failure rate is positively correlated with the dose rate of the ribbon ion beam, that is, the greater the dose rate, the more device voltage offset failures, and the smaller the dose rate, the smaller the number of device voltage offset failures. Among them, the smaller the dose rate of the ribbon ion beam, the larger the contact area between the ribbon ion beam and the wafer, which helps to improve the uniformity of wafer ion implantation, improve the performance of device voltage offset in the wafer, and improve the consistency of device performance in the wafer, and the degree of damage to the wafer lattice is relatively small.

[0033] In order to obtain a ribbon ion beam with a lower dose rate during wafer ion implantation, the present invention provides a method for improving the uniformity of wafer ion implantation. In the method for improving the uniformity of wafer ion implantation, the wafer is implanted with ions using a ribbon ion beam generated by an ion implanter, the ion implanter includes a first coil group and a second coil group, the first coil group is used to adjust and control the width, height and current of the ribbon ion beam, the second coil group is used to adjust and control the height and current of the ribbon ion beam, and the dose rate of the ribbon ion beam is related to the current and height of the ribbon ion beam.

[0034] The method for improving the uniformity of ion implantation of wafers proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0035] Figure 6 A schematic diagram of a process for improving wafer ion implantation uniformity provided by an embodiment of the present invention. Figure 6 As shown, the method for improving the uniformity of wafer ion implantation includes:

[0036] Step S1, adjusting the current of the first coil group to obtain the current values ​​of multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a first relationship curve according to the current values ​​of the multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, wherein a first range in the first relationship curve is a low value range of the dose rate;

[0037] Step S2, adjusting the current of the second coil group to obtain the current values ​​of multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a second relationship curve according to the current values ​​of the multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, wherein the second range in the second relationship curve is a low value range of the dose rate;

[0038] Step S3, obtaining a first current value range of the first coil group corresponding to the first range based on the first relationship curve, and obtaining a second current value range of the second coil group corresponding to the second range based on the second relationship curve;

[0039] Step S4, combining the current values ​​within the first current value range and the current values ​​within the second current value range to test the dose rate of the ribbon ion beam and obtain the minimum dose rate of the ribbon ion beam, using the current value of the first coil group corresponding to the minimum dose rate as the current parameter of the first coil group, and using the current value of the second coil group corresponding to the minimum dose rate as the current parameter of the second coil group.

[0040] It should be understood that although Figure 6 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 6 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0041] The method for improving wafer ion implantation uniformity of this embodiment is applicable to, but not limited to, a high beam current ion implanter. For example, the ion implanter may be a ribbon beam implanter, but not limited to this.

[0042] The first coil group may include two groups of coils arranged opposite to each other in an upper and lower direction, and the central axis of the coils extends in the horizontal direction. The first coil group is used to adjust and control the width, height and current of the ribbon ion beam; that is, adjusting the current of the first coil group will affect the width, height and current of the ribbon ion beam. Fig. 9 and Fig.10 As shown, the width of the ribbon ion beam is the dimension in the X direction, the height of the ribbon ion beam is the dimension in the Y direction, and the surface of the wafer is located in the XY plane.

[0043] The second coil group may include two groups of coils arranged opposite to each other, and the central axis of the coils is extended in the vertical direction. The second coil group is used to adjust and control the height and current of the ribbon ion beam, that is, adjusting the current of the second coil group will affect the height and current of the ribbon ion beam. It should be noted that the influence of the current of the second coil group on the width of the ribbon ion beam is very small and can be ignored.

[0044] In this embodiment, the ribbon ion beam passes through the first coil group and the second coil group in sequence before irradiating the wafer, that is, in the movement path of the ribbon ion beam, the first coil group is in front and the second coil group is in the back.

[0045] Step S1 is executed to adjust the current of the first coil group, obtain the current values ​​of multiple groups of the first coil group and the corresponding dose rates of the ribbon ion beam, the current value of the first coil group and the corresponding dose rate of the ribbon ion beam are a group, and a first relationship curve is obtained according to the current values ​​of the multiple groups of the first coil group and the corresponding dose rates of the ribbon ion beam, the first relationship curve is the relationship curve between the current value of the first coil group and the dose rate of the ribbon ion beam. In the first relationship curve, the first range is the low value range of the dose rate.

[0046] In the present application, the dose rate of the ribbon ion beam is Dose rate, and Dose rate=Beam current / Beam Height, wherein Beam current is the current of the ribbon ion beam, and Beam Height is the height of the ribbon ion beam.

[0047] Figure 7 A relationship diagram of the current value of the first coil group and the height, current and dose rate of the ribbon ion beam provided in one embodiment of the present invention.

[0048] refer to Figure 7 As shown, in the step of adjusting the current of the first coil group, the current and height of the ribbon ion beam corresponding to the current value of each first coil group can be recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each first coil group can be calculated based on the current and height of the ribbon ion beam.

[0049] It should be noted that, in the process of adjusting the current of the coil group, the current and height of the ribbon ion beam can be directly read from the machine end.

[0050] In this embodiment, when calculating the dose rate, the current unit of the ribbon ion beam is mA, the height unit of the ribbon ion beam is mm, and the dose rate unit is mA / mm. In other embodiments, the current unit of the ribbon ion beam and the height unit of the ribbon ion beam can be adjusted to match mA and mm.

[0051] In this embodiment, in the step of adjusting the current of the first coil group, it is necessary to ensure that the width of the ribbon ion beam is greater than or equal to the diameter of the wafer. Specifically, when the current of the first coil group is within a set current range, the width of the ribbon ion beam is greater than the diameter of the wafer, so it is necessary to adjust the current of the first coil group within the set current range to ensure that the width of the ribbon ion beam is greater than the diameter of the wafer. The set current range is specifically set according to the conditions of the ion implanter and the wafer size. Exemplarily, the current of the first coil group is adjusted within the range of -12A to +12A, and can be adjusted by an integer within the range of -12A to +12A, but is not limited thereto.

[0052] In addition, in the step of adjusting the current of the first coil group, the current of the second coil group can be set to 0, so that the influence of the second coil group on the ribbon ion beam can be eliminated, so that the influence of the current of the first coil group on the dose rate can be accurately determined, and then the current parameters of the first coil group can be conveniently determined.

[0053] Execute step S2 to adjust the current of the second coil group, obtain the current values ​​of multiple groups of second coil groups and their corresponding dose rates of the ribbon ion beam, the current value of a second coil group and its corresponding dose rate are a group, and obtain a second relationship curve based on the current values ​​of the multiple groups of second coil groups and the corresponding dose rates of the ribbon ion beam. The second relationship curve is a relationship curve between the current value of the second coil group and the dose rate of the ribbon ion beam. In the second relationship curve, the second range is a low value range of the dose rate.

[0054] Figure 8 A relationship diagram of the current value of the second coil group and the height, current and dose rate of the ribbon ion beam provided in one embodiment of the present invention.

[0055] refer to Figure 8 As shown, in the step of adjusting the current of the second coil group, the current and height of the ribbon ion beam corresponding to the current value of each second coil group can be recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each second coil group can be calculated based on the current and height of the ribbon ion beam.

[0056] Exemplarily, the current of the second coil group may be adjusted within a range of -90A to +90A, and may be adjusted by an integer within a range of -90A to +90A, but is not limited thereto.

[0057] Step S3 is executed to obtain a first current value range of the first coil group corresponding to the first range based on the first relationship curve, and to obtain a second current value range of the second coil group corresponding to the second range based on the second relationship curve.

[0058] Specifically, when determining the first range, the lowest dose rate in the first relationship curve may be first confirmed, and then the lowest dose rate of the first relationship curve is used as the lower limit of the first range, and the lowest dose rate of the first relationship curve plus the set tolerance is used as the upper limit of the first range. When determining the second range, the lowest dose rate in the second relationship curve may be first confirmed, and then the lowest dose rate of the second relationship curve is used as the lower limit of the second range, and the lowest dose rate of the second relationship curve plus the set tolerance is used as the upper limit of the second range. The set tolerance may be determined according to actual conditions.

[0059] Exemplary, reference Figure 7 As shown, the minimum dose rate of the first relationship curve is 0.22, the first range can be set to 0.22~0.23, and the first current value range corresponding to the first range is 5A~11A; Figure 8 As shown, the minimum dose rate of the second relationship curve is 0.21, the second range can be set to 0.21-0.22, and the second current value range corresponding to the second range is 45A-80A.

[0060] Execute step S4, combine the current values ​​within the first current value range and the current values ​​within the second current value range to test the dose rate of the ribbon ion beam and obtain the minimum dose rate of the ribbon ion beam, use the current value of the first coil group corresponding to the minimum dose rate as the current parameter of the first coil group, and use the current value of the second coil group corresponding to the minimum dose rate as the current parameter of the second coil group.

[0061] It should be noted that, in the present embodiment, by obtaining the low value range of the dose rate of the first relationship curve and the low value range of the dose rate of the second relationship curve, the current value ranges of the two coil groups (i.e., the first coil group and the second coil group) corresponding to the two low value ranges are obtained, and then the current values ​​within the current value ranges of the two coils are combined for testing to obtain the lowest dose rate, and the current values ​​of the two coil groups corresponding to the lowest dose rate are confirmed as the current parameters of the two coil groups, so that the current parameters of the two coil groups are set with high accuracy, which can ensure that the obtained ribbon ion beam dose rate is small.

[0062] In other embodiments of the present application, the current value of the first coil group corresponding to the lowest dose rate in the first relationship curve can be confirmed as the current parameter of the first coil group, and the current value of the second coil group corresponding to the lowest dose rate in the second relationship curve can be confirmed as the current parameter of the second coil group. It should be noted that in this embodiment, it can be considered that the first range only includes the lowest dose rate of the first relationship curve, and the second range only includes the lowest dose rate of the second relationship curve. One dose rate corresponds to one first coil current value and one second coil current value, so that the current value within the first current value range and the current value within the second current value range only constitute one combination. In this way, the parameter confirmation steps of the first coil group and the second coil group are relatively simple, and the dose rate of the ribbon ion beam obtained by setting the current parameters of the coil group in this way is also relatively small, which can achieve the purpose of improving the uniformity of wafer ion implantation.

[0063] Fig. 9 FIG. 4 is a schematic diagram of a ribbon ion beam with a dose rate of 0.2 according to an embodiment of the present invention. Fig.10 FIG. 1 is a schematic diagram of a ribbon ion beam with a dose rate of 0.4 in one embodiment of the present invention. Fig. 9 As shown, when the dose rate is 0.2, the current of the ribbon ion beam is 10mA, and the height of the ribbon ion beam is 50mm; Fig.10 As shown in the figure, when the dose rate is 0.4, the current of the ribbon ion beam is 10mA, and the height of the ribbon ion beam is 25mm. It can be seen that the smaller the dose rate of the ribbon ion beam, the larger the contact area between the ribbon ion beam and the wafer, which helps to improve the uniformity of wafer ion implantation, improve the performance of device voltage offset in the wafer, improve the consistency of device performance in the wafer, and less damage to the wafer lattice.

[0064] Exemplary, reference Figure 3 As shown, after setting the current parameters of the first coil group and the second coil group, ion implantation can be performed on the wafer in four steps, wherein after one step of ion implantation is completed, the wafer is rotated 90° before the next step of ion implantation is performed, but the present invention is not limited thereto.

[0065] Exemplarily, after setting the current parameters of the first coil group and the second coil group, a ribbon ion beam formed by an ion implanter may be used to implant the source and drain regions of the device into the wafer to adjust the voltage offset of the device, but the present invention is not limited thereto.

[0066] In the method for improving the uniformity of wafer ion implantation provided by the present invention, the current of the first coil group is adjusted to obtain the dose rate of the ribbon ion beam corresponding to the current value of each first coil group, and a first relationship curve is obtained according to the current values ​​of multiple groups of first coil groups and the dose rate of the ribbon ion beam. The current of the second coil group is adjusted to obtain the dose rate of the ribbon ion beam corresponding to the current value of each second coil group, and a second relationship curve is obtained according to the current values ​​of multiple groups of second coil groups and the dose rate of the ribbon ion beam. Then, a low value range of the dose rate in the first relationship curve and its corresponding first current value range of the first coil group are obtained, a low value range of the dose rate in the second relationship curve and its corresponding second current value range of the second coil group are obtained, and the dose rate within the first current value range is calculated. The current value and the current value within the second current value range are combined to test the dose rate of the ribbon ion beam and obtain the minimum dose rate of the ribbon ion beam, the current value of the first coil group corresponding to the minimum dose rate is used as the current parameter of the first coil group, and the current value of the second coil group corresponding to the minimum dose rate is used as the current parameter of the second coil group. The unexpected effect is that the dose rate of the obtained ribbon ion beam is small, or even minimum, so that the contact area between the ribbon ion beam and the wafer is relatively large, which helps to improve the uniformity of wafer ion implantation, improve the performance of device voltage offset in the wafer, improve the problem of frequent voltage offset failure of devices in the wafer, improve the consistency of device performance in the wafer, and less damage to the wafer lattice.

[0067] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the uniformity of ion implantation in a wafer, characterized in that: The wafer is subjected to ion implantation using a ribbon ion beam generated by an ion implanter, the ion implanter comprising a first coil group and a second coil group, the first coil group being used to adjust and control the width, height and current of the ribbon ion beam, the second coil group being used to adjust and control the height and current of the ribbon ion beam, the dose rate of the ribbon ion beam being related to the current and height of the ribbon ion beam, the method for improving the uniformity of wafer ion implantation comprising: Adjusting the current of the first coil group to obtain the current values ​​of multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a first relationship curve according to the current values ​​of the multiple groups of the first coil groups and the corresponding dose rates of the ribbon ion beams, wherein the first range in the first relationship curve is a low value range of the dose rate; Adjusting the current of the second coil group to obtain the current values ​​of multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, and obtaining a second relationship curve according to the current values ​​of the multiple groups of the second coil groups and the corresponding dose rates of the ribbon ion beams, wherein the second range in the second relationship curve is a low value range of the dose rate; obtaining a first current value range of the first coil group corresponding to the first range based on the first relationship curve, and obtaining a second current value range of the second coil group corresponding to the second range based on the second relationship curve; and The current values ​​within the first current value range and the current values ​​within the second current value range are combined to test the dose rate of the ribbon ion beam and obtain the minimum dose rate of the ribbon ion beam, and the current value of the first coil group corresponding to the minimum dose rate is used as the current parameter of the first coil group, and the current value of the second coil group corresponding to the minimum dose rate is used as the current parameter of the second coil group.

2. The method for improving wafer ion implantation uniformity according to claim 1, characterized in that: The first range only includes the lowest dose rate of the first relationship curve, and the second range only includes the lowest dose rate of the second relationship curve; the current value of the first coil group corresponding to the lowest dose rate in the first relationship curve is confirmed as the current parameter of the first coil group; the current value of the second coil group corresponding to the lowest dose rate in the second relationship curve is confirmed as the current parameter of the second coil group.

3. The method for improving wafer ion implantation uniformity as claimed in claim 1, characterized in that: The lowest dose rate of the first relationship curve is used as the lower limit of the first range, and the lowest dose rate of the first relationship curve plus a set tolerance is used as the upper limit of the first range; The lowest dose rate of the second relationship curve is used as the upper limit of the second range, and the lowest dose rate of the second relationship curve plus a set tolerance is used as the upper limit of the second range.

4. The method for improving wafer ion implantation uniformity as claimed in claim 1, characterized in that: In the step of adjusting the current of the first coil group, the current of the second coil group is set to 0.

5. The method for improving wafer ion implantation uniformity according to claim 1, characterized in that: When the current of the first coil group is within a set current range, the width of the ribbon ion beam is greater than or equal to the diameter of the wafer; in the step of adjusting the current of the first coil group, the current of the first coil group is adjusted within the set current range.

6. The method for improving wafer ion implantation uniformity according to claim 1, characterized in that: The dose rate of the ribbon ion beam is Dose rate, where Dose rate=Beam current / Beam Height, wherein Beam current is the current of the ribbon ion beam, and Beam Height is the height of the ribbon ion beam.

7. The method for improving wafer ion implantation uniformity according to claim 1, characterized in that: In the step of adjusting the current of the first coil group, the current and height of the ribbon ion beam corresponding to the current value of each first coil group are recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each first coil group is calculated based on the current and height of the ribbon ion beam; in the step of adjusting the current of the second coil group, the current and height of the ribbon ion beam corresponding to the current value of each second coil group are recorded, and the dose rate of the ribbon ion beam corresponding to the current value of each second coil group is calculated based on the current and height of the ribbon ion beam.

8. The method for improving wafer ion implantation uniformity as claimed in claim 1, characterized in that: The current of the first coil group is adjusted within the range of -12A to +12A.

9. The method for improving wafer ion implantation uniformity as claimed in claim 1, characterized in that: The current of the second coil group is adjusted within the range of -90A to +90A.

10. The method for improving wafer ion implantation uniformity according to claim 1, characterized in that: The ribbon ion beam passes through the first coil group and the second coil group in sequence and then irradiates the wafer.

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