A method of online assisted monitoring of ion implantation

Abstract

The present application provides a kind of method for online auxiliary monitoring ion implantation, increase multiple measurement pads in pad for film thickness measurement in each die of wafer;While ion implantation is carried out in the area of wafer to be implanted, ion implantation is carried out in the measurement pad;When ion implantation occurs abnormally, the X-ray photoelectron spectroscopy signal value of measurement pad is obtained;Linear equation of X-ray photoelectron spectroscopy signal value and ion implantation dose is provided;The X-ray photoelectron spectroscopy signal value of measurement pad is substituted into linear equation, and the actual ion implantation dose of measurement pad is obtained;Actual ion implantation dose is compared with the information of make-up, if the comparison result is within the allowable difference range, then execute make-up task;If the comparison result is not within the allowable difference range, then wafer is scrapped.The present application can accurately judge the actual operation condition of wafer, so as to realize online auxiliary monitoring of ion implantation process, reduce production cost and improve production yield.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for online assisted monitoring of ion implantation. Background Technology

[0002] In semiconductor wafer manufacturing, the monitoring of ion implantation processes is usually done offline, mainly because the dose and energy of implanted ions are typically monitored using a four-probe method for resistance testing. This destructive testing method makes it unsuitable for in-line monitoring.

[0003] During ion implantation, interruptions are common due to abnormalities or unforeseen circumstances such as unstable ion beams, power supply fluctuations, and software crashes. While interruptions caused by unstable ion beams can be corrected by automatically generated top-off tasks from the ion implantation machine with high accuracy and minimal impact on the wafer fabrication process, the feasibility of automatically generated top-off tasks is significantly reduced in the event of software crashes or power outages. This is especially true when the top-off task differs from the machine's operation log, making it impossible to accurately determine the actual wafer fabrication status and significantly impacting the wafer fabrication process.

[0004] Because ion implantation processes typically lack real-time in-line monitoring, wafers experiencing abnormal operations usually only reveal the problem after the entire process is completed and wafer acceptability testing (WAT) or yield testing is performed. This not only increases production costs but also impacts production line yield. Therefore, suitable in-line testing methods are needed to promptly identify wafers with operational abnormalities. Currently, there is no suitable in-line testing method for monitoring the ion implantation process. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an online auxiliary monitoring method for ion implantation, which solves the problem that the ion implantation process in the prior art lacks a real-time online monitoring method, thereby affecting the production line yield.

[0006] To achieve the above and other related objectives, the present invention provides a method for online assisted monitoring of ion implantation, comprising at least:

[0007] Step 1: Add multiple measurement pads to the pads used for film thickness measurement in each die of the wafer;

[0008] Step 2: Simultaneously perform ion implantation on the measurement pad while performing ion implantation on the area to be implanted on the wafer;

[0009] Step three, when the ion implantation operation is abnormal, the measurement pad is tested by X-ray photoelectron spectroscopy to obtain the X-ray photoelectron spectroscopy signal value of the measurement pad;

[0010] Step four, a linear equation of X-ray photoelectron spectroscopy signal value and ion implantation dose is provided;

[0011] Step five, the X-ray photoelectron spectroscopy signal value of the measurement pad in step three is substituted into the linear equation in step four to obtain the actual ion implantation dose of the measurement pad;

[0012] Step six, the actual ion implantation dose in step five is compared with the re-implantation information of the ion implantation machine when the ion implantation operation is abnormal, if the comparison result is within the allowable difference range, the re-implantation task is executed, if the comparison result is not within the allowable difference range, the wafer is scrapped.

[0013] Preferably, the measurement pad in step one is consistent with the material of the substrate.

[0014] Preferably, the ion implantation in the wafer to be implanted area in step two is performed multiple times, and each time the ion implantation is performed in the same measurement pad with different types.

[0015] Preferably, when the measurement pad is tested in step three, the measurement points are distributed in each row of die of the wafer.

[0016] Preferably, the X-ray photoelectron spectroscopy signal value in step three is the atomic percentage or atomic concentration value.

[0017] Preferably, the re-implantation information in step six is the required implantation dose for continuing ion implantation.

[0018] Preferably, the allowable difference range in step six is less than or equal to 3%.

[0019] As described above, the online auxiliary monitoring ion implantation method of the present application has the following beneficial effects: the online auxiliary monitoring ion implantation process method provided by the present application uses X-ray photoelectron spectroscopy to test the ion dose of the implanted wafer for abnormal operation wafer, which can accurately judge the actual operation of the wafer, so as to realize the online auxiliary monitoring of the ion implantation process, reduce the production cost and improve the production yield. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The schematic diagram of the plurality of measurement pad positions added by the present application is shown;

[0021] Figure 2The diagram shows the XPS test distribution of the multiple measurement pads added in this invention.

[0022] Figure 3 The graph shows the linear equation between the Ge ion implantation dose before annealing and the percentage of XPS atoms in this invention.

[0023] Figure 4 The graph shows the linear equation between the Ge ion implantation dose after annealing and the percentage of XPS atoms in this invention.

[0024] Figure 5 The diagram shown is a flowchart of the online assisted monitoring ion implantation method of the present invention. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] Please see Figures 1 to 5 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0027] This invention provides a method for online assisted monitoring of ion implantation, such as... Figure 5 As shown, Figure 5 The flowchart shown is a method for online assisted monitoring of ion implantation according to the present invention, which includes at least the following steps:

[0028] Step 1: Add multiple measurement pads to the pads used for film thickness measurement in each die of the wafer;

[0029] Furthermore, in this embodiment, the measuring pad in step one is made of the same material as the substrate.

[0030] like Figure 1 As shown, six measurement pads, namely I1, I2, I3, I4, I5, and I6, are added to the film thickness measurement pad in each die of the wafer. Each pad is always consistent with the wafer substrate material and no thin film is grown.

[0031] Step 2: Simultaneously perform ion implantation on the measurement pad while performing ion implantation on the wafer's implantation area;

[0032] Further, the ion implantation in the wafer to be implanted region in step two of the embodiment is performed multiple times, and each time the ion implantation is performed in the same measurement pad with a different type of ion.

[0033] The embodiment simultaneously implants pad F when performing source-drain doping ion implantation, and the implantation ions include phosphorus, boron and germanium.

[0034] Step three, when the ion implantation operation is abnormal, the measurement pad is tested by X-ray photoelectron spectroscopy to obtain the X-ray photoelectron spectroscopy signal value of the measurement pad;

[0035] Further, the measurement points are distributed in each row of die of the wafer when the measurement pad is tested in step three of the embodiment.

[0036] Further, the X-ray photoelectron spectroscopy signal value in step three of the embodiment is the atomic percentage or atomic concentration value.

[0037] In the embodiment, when germanium is implanted, the ion implantation operation is abnormal, and it is necessary to determine whether the machine log is accurate, so it is necessary to measure the measurement pad F. As shown in Figure 2 the position map of the measurement pad is distributed in each row of die, and 71 points are selected for measurement, and each row of pad needs to have a measurement point for measurement. Measurement is performed by X-ray photoelectron spectroscopy, and the Ge atomic percentage of the measurement point is read.

[0038] Step four, providing a linear equation of the X-ray photoelectron spectroscopy signal value and the ion implantation dose;

[0039] As shown in Figure 3 the linear equation between the X-ray photoelectron spectroscopy signal value and the ion implantation dose is obtained, the implantation energy is the same as the source-drain doping germanium ion implantation energy, which is 7KeV, and the implantation dose is selected in the range of 0.1-1E15, thereby obtaining the linear equation.

[0040] Step five, substituting the X-ray photoelectron spectroscopy signal value of the measurement pad in step three into the linear equation in step four to obtain the actual ion implantation dose of the measurement pad;

[0041] Step six, providing the re-print information of the ion implantation machine when the ion implantation operation is abnormal, comparing the actual ion implantation dose in step five with the re-print information, if the comparison result is within the allowable difference range, performing the re-print task; if the comparison result is not within the allowable difference range, performing the scrap processing on the wafer.

[0042] The present application further, the injection dose required for continuing ion implantation in step six of the embodiment is the supplement information.

[0043] The present application further, the allowable difference range in step six of the embodiment is less than or equal to 3%.

[0044] The signal obtained by X-ray photoelectron spectroscopy test in the embodiment is substituted into the linear equation Figure 2 The actual injection dose can be calculated, and the actual injection dose is compared with the machine top off display information. If the comparison result is within the allowable difference range, that is, the difference of 3% dose, the top off task is executed, and if the comparison result is not within the allowable difference range, the wafer is scrapped.

[0045] As shown in Figure 4 If the wafer has been executed top off task by calculation, and the wafer has been subjected to subsequent annealing treatment, the above method can still be used to obtain the linear equation between the X-ray photoelectron spectroscopy signal value after annealing and the ion implantation dose. If the actual injection dose is compared with the machine top off display information, the comparison result is within the allowable difference range, that is, the difference of 3% dose, the other processes are continued to be completed, and if the comparison result is not within the allowable difference range, the wafer is scrapped.

[0046] In summary, the method for online auxiliary monitoring of ion implantation process provided by the present application can test the ion dose of the implanted wafer by X-ray photoelectron spectroscopy for the wafer with abnormal operation, can accurately judge the actual operation condition of the wafer, so as to realize online auxiliary monitoring of ion implantation process, reduce production cost and improve production yield. Therefore, the present application effectively overcomes the shortcomings in the prior art and has high industrial utilization value.

[0047] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method of on-line assisted monitoring of ion implantation, characterized by, At least comprising: Step one, adding multiple measurement pads in the pads for film thickness measurement in each die of the wafer, the measurement pads are consistent with the material of the substrate; Step two, performing ion implantation into the measurement pads while performing ion implantation in the wafer implantation area, the ion implantation in the wafer implantation area is performed multiple times, and each time the ion implantation is performed in the same measurement pad with different species; Step three, when the ion implantation operation is abnormal, testing the measurement pad by X-ray photoelectron spectroscopy to obtain the X-ray photoelectron spectroscopy signal value of the measurement pad; Step four, providing a linear equation of X-ray photoelectron spectroscopy signal value and ion implantation dose; Step five, substituting the X-ray photoelectron spectroscopy signal value of the measurement pad in step three into the linear equation in step four to obtain the actual ion implantation dose of the measurement pad; Step six, providing the rework information of the ion implantation machine when the ion implantation operation is abnormal, comparing the actual ion implantation dose in step five with the rework information, if the comparison result is within the allowable difference range, performing the rework task, if the comparison result is not within the allowable difference range, discarding the wafer.

2. The method of online assisted monitoring of ion implantation according to claim 1, wherein: In step three, the measurement points are distributed in each row of die of the wafer.

3. The method of online assisted monitoring of ion implantation according to claim 1, wherein: The X-ray photoelectron spectroscopy signal value in step three is the atomic percentage or atomic concentration value.

4. The method of online assisted monitoring of ion implantation according to claim 1, wherein: The rework information in step six is the required implantation dose for continuing ion implantation.

5. The method of online assisted monitoring of ion implantation according to claim 1, wherein: The allowable difference range in step six is less than or equal to 3%.

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