A real-time detection device applied to FIB lithography technology

Abstract

The application discloses a real-time detection device applied to FIB (Focused Ion Beam) lithography technology, which comprises N ion guns for ion beam lithography and N electron guns for detection after ion beam lithography to ensure the quality of lithography, wherein N is greater than or equal to 1, and the ion guns and the electron guns are respectively controlled and synchronously work. The application has the following beneficial effects: the electron gun and the ion gun are separated by a certain distance, can synchronously work, can ensure that they do not interfere with each other (especially the electron gun does not interfere with the work of the ion gun), can realize real-time detection, and can greatly improve the efficiency of ion beam lithography and detection; the electron gun and the ion gun are respectively controlled, and better real-time monitoring can be realized; the electron gun is controlled and works independently, and better monitoring effect can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of real-time detection equipment of following type applied in FIB lithography technology. BACKGROUND

[0002] As shown in Figure 1 The detection method of current traditional photolithography process is to carry out photolithography (glue, exposure, development) in photolithography machine (unit) first, then semiconductor wafer is sent to separate detection equipment, and the photolithography effect is detected, such as whether the photolithography size meets the standard in CDSEM, which cannot achieve real-time monitoring effect.

[0003] And FIB lithography technology equipped with secondary electron probe or independent electron gun can realize real-time monitoring, and FIB lithography technology is a completely new photolithography technology for chip manufacturing. As shown in Figure 2 The detection scheme of current FIB lithography technology equipped with independent electron gun is that electron gun and ion gun are gathered at the same point. When the scheme as shown in Figure 2 The electron gun is closed first, the ion gun is opened, and the ion gun is focused on the point A of interest. Then, the ion gun is closed, and the electron gun is switched to, and the electron gun is opened, and the electron gun is also focused on the point A of interest for photographing detection. Then, the electron gun is closed, and the ion gun is opened, and the next point of interest on the process is switched from the point A of interest for continuous work. That is, the detection scheme of the existing FIB lithography technology is to stop the ion gun after FIB processing, and to image at the same point of interest by using the electron gun. The efficiency of this detection method is extremely low, which affects the efficiency of ion beam lithography. Of course, the electron gun and the ion gun can be opened at the same time, but they will interfere with each other.

[0004] As shown in Figure 3 In the existing detection scheme, the ion gun can also be equipped with a secondary electron probe to collect secondary electron signals excited by the ion beam for real-time imaging, so that real-time imaging can be realized when the ion gun is working. However, the ion beam signal noise is large, and the image effect obtained is as shown in Figure 4 The definition is poor. The ion gun lithography action can also be stopped, and the secondary electron probe can be used for imaging alone, but the imaging effect is also poor. SUMMARY

[0005] The technical problem to be solved by the present application is that the detection scheme of the current FIB lithography technology equipped with independent electron gun is extremely low in efficiency.

[0006] In order to solve the above technical problems, the technical scheme of the present application discloses a kind of real-time detection equipment applied in FIB lithography technology, including N ion guns for ion beam lithography and N electron guns one for detection after ion beam lithography to ensure the quality of lithography, N≥1, characterized in that, ion gun and electron gun one are controlled respectively.

[0007] At the current time, the ion gun and the electron gun one are focused on the current N focus points and the upper N focus points adjacent to the current N focus points in the process, and the electron gun one completes detection at the upper N focus points while the ion gun completes ion beam lithography at the current focus points;

[0008] At the next time, the ion gun is focused on the lower N focus points adjacent to the current focus points in the process, the electron gun one is focused on the current focus points, and the ion gun and the electron gun are switched to the next row to continue working after traversing all focus points of the current process row on the semiconductor wafer.

[0009] Preferably, N electron guns two for detection before ion beam lithography are further included to ensure that the ion beam lithography precondition meets the expectation, and the ion gun, the electron gun one and the electron gun two are controlled respectively.

[0010] At the current time, the ion gun is focused on the current focus points, the electron gun one is focused on the upper N focus points adjacent to the current focus points in the process, and the electron gun two is focused on the lower N focus points adjacent to the current focus points in the process, and the electron gun one completes detection at the upper N focus points while the ion gun completes ion beam lithography at the current focus points, and the electron gun two completes detection at the lower N focus points.

[0011] At the next time, the ion gun is focused on the lower N focus points, the electron gun one is focused on the current focus points, and the electron gun two is focused on the lower lower N focus points adjacent to the lower N focus points in the process.

[0012] Preferably, the ion gun is a multi-array ion gun.

[0013] Preferably, the electron gun one and / or the electron gun two are multi-array electron guns.

[0014] Preferably, the ion gun is equipped with a secondary electron probe, a backscattering electron probe, an EDX probe or a SIMS probe.

[0015] Preferably, when the ion gun is equipped with the SIMS probe, whether the etching depth during lithography is sufficient is determined according to the composition information obtained by the SIMS probe.

[0016] Preferably, when the ion gun is equipped with the EDX probe, whether the etching depth during lithography is sufficient is determined according to the depth information obtained by the EDX probe.

[0017] Preferably, the electron gun one and / or the electron gun two are equipped with a secondary electron probe or a backscattering electron probe.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1) The electron gun and ion gun are separated by a certain distance, which can achieve synchronous operation while ensuring that they do not interfere with each other (especially the electron gun will not interfere with the operation of the ion gun), thus realizing real-time detection and greatly improving the efficiency of ion beam lithography and detection.

[0020] 2) The electron gun and ion gun are controlled separately, which allows for better "real-time monitoring";

[0021] 3) The electron gun can be controlled and operated independently, which can achieve better monitoring results. Attached Figure Description

[0022] Figure 1 This illustrates the current traditional photolithography detection method;

[0023] Figure 2 This illustrates the current detection scheme for FIB lithography technology equipped with an independent electron gun;

[0024] Figure 3 This illustrates a scheme where an existing ion gun is equipped with a secondary electronic probe;

[0025] Figure 4 The illustration shows the imaging effect after collecting the secondary electron signal excited by the ion beam for ion beam imaging.

[0026] Figure 5 This invention illustrates one configuration of the real-time inspection device disclosed in this invention, which is applied to FIB lithography technology.

[0027] Figure 6 This illustrates the imaging effect after collecting the secondary electron signal excited by the electron beam and performing ion beam imaging.

[0028] Figure 7 This illustrates another configuration of the real-time inspection device disclosed in this invention for use in FIB lithography technology. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] Example 1

[0031] The real-time detection device applied to the FIB lithography technology disclosed by the embodiment of the present application at least comprises an electron gun and an ion gun, the electron gun and the ion gun are separated by a certain distance, are separately controlled, and the distance between the electron gun and the ion gun is equivalent to the distance between two adjacent focus points (such as 100 um). Furthermore, at the same time, the electron gun and the ion gun do not focus on the same focus point, but focus on two adjacent focus points. As shown in Figure 5 , the ion gun and the electron gun are simultaneously turned on and work, assuming that the ion gun focuses on focus point B at this time, and at the same time, the electron gun focuses on focus point A. The ion gun works at focus point B and completes lithography. At the same time when the ion gun works, the electron gun works at focus point A and detects the part of the semiconductor wafer that has completed lithography, thereby ensuring the lithography quality of the position of focus point A. Subsequently, the electron gun switches to work at focus point B, and the ion gun switches to work at the next focus point (for example, focus point C) adjacent to focus point B in the process. In this way, FIB lithography of all focus points in any row on the semiconductor wafer is completed. It should be noted that: first, in the FIB lithography technology, the semiconductor wafer completes lithography row by row, each row has multiple focus points, assuming that the focus points in each row are arranged in the horizontal position, for each row of focus points, according to the process design, the lithography can be completed from left to right in turn, or from right to left in turn, and the present application does not limit the order; second, there will be a distance of "empty cutting point" in each row, when the ion gun works at the first non-"empty cutting point" focus point of the current row, the electron gun works at the "empty cutting point", at this time, the electron gun is "empty" and the electron gun at the "empty cutting point" is turned off, when the electron gun switches to work at the focus point where the ion gun is originally located, the electron gun is turned on again; and when the ion gun completes the work at the last focus point of the current row, the ion gun is turned off, and the same is true for the electron gun.

[0032] Under the technical inspiration given by the present application, a person skilled in the art can also set up more than two ion guns and set up corresponding number of electron guns according to the needs. Multiple ion guns can simultaneously perform lithography at multiple focus points, and multiple electron guns can simultaneously perform detection work at multiple focus points, thereby achieving higher work efficiency. A person skilled in the art can also use array type electron guns and array type ion guns according to the needs, which can also improve the work efficiency.

[0033] As shown in Figure 5 , the electron gun and the ion gun can each carry a secondary electron probe. The secondary electron probe carried by the ion gun is used to collect the secondary electron signal excited when the ion beam works, thereby ensuring more real-time monitoring. The secondary electron probe carried by the electron gun is used to collect the secondary electron signal excited when the electron beam works, as shown in Figure 6 , which can ensure clearer image results.

[0034] Meanwhile, the ion gun can be equipped with multiple probes other than the secondary electron probe, such as a backscattered electron probe, an EDX probe, a SIMS probe, and the like. When the ion gun is equipped with an EDX probe or a SIMS probe, the etching depth can be determined according to the component information, that is, whether the ion beam lithography (lithography + etching) reaches the etching stop layer, to determine whether to stop the ion beam. In the traditional etching process, the etching is stopped at the etching stop layer by controlling the etching selectivity. However, the technical solution disclosed in the embodiments of the present application can monitor the components in real time by the EDX probe or the SIMS probe to control the etching to stop at the etching stop layer.

[0035] Specifically, if the ion gun is equipped with a SIMS probe, the secondary ions etched out will be collected by the SIMS probe. If the SIMS probe only detects Si / O signals without Cu signals, it means that the etching depth is not enough. If the SIMS probe detects Cu signals, it means that the etching depth is enough, and the etching (lithography) can be stopped. Compared with the traditional solution, the technical solution disclosed in the embodiments of the present application is more accurate in sensing and controlling the entire etching (lithography) Etch.

[0036] The EDX probe will collect information at a certain depth. If the ion gun is equipped with an EDX probe, the etching depth can be determined according to the intensity of the received signal. Similarly, compared with the traditional solution, the technical solution disclosed in the embodiments of the present application is more accurate in sensing and controlling the entire etching (lithography) Etch.

[0037] Embodiment 2

[0038] As shown in Figure 2 The real-time detection device applied to the FIB lithography technology disclosed in the embodiments of the present application includes two electron guns and an ion gun. The two electron guns are defined as a front electron gun and a lagging electron gun, and the front electron gun, the ion gun, and the lagging electron gun. The front electron gun and the ion gun and the ion gun and the lagging electron gun are separated by a certain distance and are controlled separately. The distance between the front electron gun and the ion gun and the distance between the ion gun and the lagging electron gun is comparable to the distance between two adjacent points of interest (such as 100 um). Further, at the same time, the front electron gun, the ion gun, and the lagging electron gun do not focus on the same point of interest, but focus on three adjacent points of interest. The front electron gun, the ion gun, and the lagging electron gun are turned on at the same time. Assuming that the front electron gun, the ion gun, and the lagging electron gun focus on the point of interest C, the point of interest B, and the point of interest A at the current time, respectively, then at the next time, the front electron gun, the ion gun, and the lagging electron gun focus on the point of interest D (the next point of interest adjacent to the point of interest C in the process), the point of interest C, and the point of interest B, respectively.

[0039] In the embodiment of the present application, the pre-electron gun is used for detection before ion beam lithography, to ensure that the preconditions of ion beam lithography meet the expectations, and any problems found can be timely prevented, remedied, and compensated. Specifically, before the pre-electron gun ion gun operates, a pre-check is performed to ensure that there are no quality problems such as particles, contamination, cracks, scratches, misalignment, etc., to ensure a clean field, which can be judged in the form of image comparison. The ion gun is mainly used for lithography and can be matched with a secondary electron probe to monitor the status of the lithography process in real time. The lag electron gun is used for detection after ion beam lithography, to ensure the quality of lithography, and corresponding handling and compensation measures can also be taken for problems found.

[0040] Under the technical inspiration given by the present application, a person skilled in the art can also set up more than two ion guns as needed, and set up corresponding numbers of pre-electron guns and lag electron guns. Multiple ion guns can simultaneously perform lithography in multiple points of interest, while multiple pre-electron guns and multiple lag electron guns can simultaneously perform detection work in multiple points of interest, with higher work efficiency. A person skilled in the art can also use array electron guns as pre-electron guns and lag electron guns as needed, and use array ion guns, which can also improve work efficiency.

[0041] Other structures and working principles of the present embodiment are the same as those of Embodiment 1, which will not be described here again.

Claims

1. A real-time detection device applied in FIB lithography technology, comprising N ion guns for ion beam lithography and N electron guns for detection after ion beam lithography to ensure the quality of lithography, N≥1, characterized in that, The ion gun and the electron gun are controlled respectively; At the current time, the ion gun and the electron gun are focused on the current N focus points and the upper N focus points adjacent to the current N focus points in the process, and the electron gun completes detection on the upper N focus points while the ion gun completes ion beam lithography on the current focus points; At the next time, the ion gun is focused on the lower N focus points adjacent to the current focus points in the process, the electron gun is focused on the current focus points, and the ion gun and the electron gun are switched to the next row to continue working after traversing all focus points of the current process row on the semiconductor wafer.

2. The real-time detection device for use in FIB lithography of claim 1, wherein, N electron guns two are further included for detection before ion beam lithography to ensure that the ion beam lithography precondition meets the expectation, and the ion gun, the electron gun one and the electron gun two are controlled respectively; At the current time, the ion gun is focused on the current focus points, the electron gun one is focused on the upper N focus points adjacent to the current focus points in the process, and the electron gun two is focused on the lower N focus points adjacent to the current focus points in the process, and the electron gun one completes detection on the upper N focus points while the ion gun completes ion beam lithography on the current focus points, and the electron gun two completes detection on the lower N focus points; At the next time, the ion gun is focused on the lower N focus points, the electron gun one is focused on the current focus points, and the electron gun two is focused on the lower N focus points adjacent to the lower N focus points in the process.

3. A real-time detection device for use in FIB lithography as claimed in claim 1 or 2, characterized in that, The ion gun is a multi-array ion gun.

4. The real-time detection device for use in FIB lithography according to claim 1 or 2, wherein, The electron gun one and / or the electron gun two are multi-array electron guns.

5. The real-time detection device for use in FIB lithography of claim 1 or 2, wherein, The ion gun is equipped with a secondary electron probe, a backscattering electron probe, an EDX probe or a SIMS probe.

6. A real-time detection device for use in FIB lithography as claimed in claim 5, wherein, When the ion gun is equipped with the SIMS probe, the composition information obtained by the SIMS probe is used to determine whether the etching depth during lithography is sufficient.

7. A real-time inspection apparatus for use in FIB lithography as claimed in claim 5, wherein, When the ion gun is equipped with the EDX probe, the depth information obtained by the EDX probe is used to determine whether the etching depth during lithography is sufficient.

8. A real-time detection device for use in FIB lithography as claimed in claim 1 or 2, characterized in that, The electron gun one and / or the electron gun two are equipped with a secondary electron probe or a backscattering electron probe.

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