Discharge plasma extreme ultraviolet light source power measuring device and measuring method

Abstract

The application provides a kind of discharge plasma type extreme ultraviolet light source power measuring device and measuring method, the device includes: optical filter, for the light of DPP type light source is filtered out, forms light beam after filtering, it is located between first vacuum cavity and second vacuum cavity;Reflecting mirror, in second vacuum cavity, for the light beam after filtering is filtered in band, forms band in extreme ultraviolet light beam;Extreme ultraviolet photodiode, for the light signal of band in extreme ultraviolet light beam is changed into current signal;Calculation module, for obtaining the band in extreme ultraviolet light power of DPP type light source under specific solid angle according to current signal and the current-power response curve of extreme ultraviolet photodiode;And according to the extreme ultraviolet light power of DPP type light source under specific solid angle, obtains the extreme ultraviolet light power of DPP type light source.The device structure of the application is simple, easy to build experimental platform, can accurately, quickly measure the extreme ultraviolet light power of DPP type light source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of extreme ultraviolet light sources, in particular to a discharge plasma type extreme ultraviolet light source power measuring device and method. BACKGROUND

[0002] The discharge plasma type (DPP) extreme ultraviolet light source generates discharge plasma by high-frequency pulse electric field excitation of gas (such as xenon or xenon fluoride), and then radiates extreme ultraviolet light. The discharge plasma type extreme ultraviolet light source is the first choice for desktop extreme ultraviolet light sources due to its relatively simple structure and high light power. The DPP type light source can meet the needs of laboratory level detection fields such as photoresist detection and mask detection due to its relatively simple structure, small footprint and high output power. However, due to the extremely wide spectral range of the DPP type light source, covering soft x-ray to infrared light, the measurement of the in-band extreme ultraviolet (13.5 nm, ±1%) light power of the DPP type light source for application in extreme ultraviolet lithography and photoresist detection is a difficult problem.

[0003] At present, there is no mature scheme for monochromatic light power measurement of the DPP type light source containing extreme ultraviolet light, and power is one of the important evaluation standards for the DPP type light source, which has a great guiding role for the subsequent research and development and use of the light source. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a discharge plasma type extreme ultraviolet light source power measuring device and method.

[0005] The present application is realized by the following technical solutions:

[0006] According to one aspect of the present application, a discharge plasma type extreme ultraviolet light source power measuring device is provided, which comprises:

[0007] A filter is used to filter out-of-band light from the DPP type light source to form a filtered light beam; the filter is located between the first vacuum cavity and the second vacuum cavity, the first vacuum cavity comprises a light source vacuum cavity, and the second vacuum cavity is in communication with the first vacuum cavity;

[0008] A mirror is located in the second vacuum cavity, and the mirror is used to filter in-band light from the filtered light beam to form an in-band extreme ultraviolet light beam;

[0009] An extreme ultraviolet photodiode is located in the second vacuum cavity, the in-band extreme ultraviolet light beam is reflected to the detection plane of the extreme ultraviolet photodiode, and the extreme ultraviolet photodiode is used to convert the light signal of the in-band extreme ultraviolet light beam into an electric current signal;

[0010] a calculation module, configured to obtain the in-band EUV light power of the DPP light source under a specific solid angle according to the current signal and the current-power response curve of the EUV photodiode, and obtain the EUV light power of the DPP light source according to the EUV light power of the DPP light source under the specific solid angle.

[0011] Optionally, the filter is a zirconium film filter, and the spectral band range of the filtered light beam is 1-20 nm.

[0012] Optionally, the mirror is placed at an angle of 45 degrees relative to the axis of the filtered light beam.

[0013] Optionally, the mirror is a Mo / Si multilayer film mirror, which comprises Mo layers and Si layers alternately stacked periodically, wherein the thickness of the Mo layer is 2.76 nm, and the thickness of the Si layer is 4.14 nm.

[0014] Optionally, the calculation module obtains the specific solid angle of the in-band EUV light beam according to the distance between the detector plane of the EUV photodiode and the DPP light source and the size of the light-sensitive element of the EUV photodiode.

[0015] Optionally, the calculation module integrates the EUV light power of the DPP light source under the specific solid angle to obtain the EUV light power over a solid angle of 2π or 4π, i.e., the EUV light power of the DPP light source.

[0016] Optionally, the calculation module is further configured to unitize the EUV light power over a solid angle of 4π to obtain the EUV light power per unit solid angle of the DPP light source.

[0017] Optionally, the device further comprises a telescopic vacuum pipeline connected to the DPP light source, the telescopic vacuum pipeline being in communication with a light source vacuum cavity, the light source vacuum cavity being provided with a first vacuum pump interface for connecting a vacuum pump, the telescopic vacuum pipeline and the internal space of the light source vacuum cavity forming the first vacuum cavity, and the second vacuum cavity being provided with a second vacuum pump interface for connecting a vacuum pump.

[0018] Optionally, the filter is fixed between the first vacuum cavity and the second vacuum cavity by a filter clamping device, and the EUV photodiode is fixed inside the second vacuum cavity by a photodiode clamping device.

[0019] According to another aspect of the present application, a method for measuring the power of a discharge plasma EUV light source is provided, which is implemented by using the discharge plasma EUV light source power measuring device described above, and the method comprises the following steps:

[0020] The DPP-type light source generates a wide-spectrum ellipsoidal light beam from x-rays to infrared light, which is filtered by a filter to form a filtered light beam;

[0021] The filtered light beam is filtered by a mirror to obtain an in-band extreme ultraviolet light beam;

[0022] The in-band extreme ultraviolet light beam is reflected on the detection plane of an extreme ultraviolet photodiode, which converts the light signal of the in-band extreme ultraviolet light beam into a current signal;

[0023] According to the current signal and the current-power response curve of the extreme ultraviolet photodiode, the in-band extreme ultraviolet light power of the DPP-type light source under a specific solid angle is obtained;

[0024] According to the extreme ultraviolet light power of the DPP-type light source under a specific solid angle, the extreme ultraviolet light power of the DPP-type light source is obtained.

[0025] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0026] 1. The measuring device provided by the present application has a simple structure, and the parts used are easy to obtain. Compared with the existing power measurement scheme, it does not need to maintain the synchronization of the spectrometer and the photodiode measurement spectrum, is easy to build an experimental platform, and obtains monochromatic light by filtering the DPP-type light source through a filter, directly measures the power of the monochromatic light, and thus obtains the extreme ultraviolet light power of the DPP-type light source. The measurement result is intuitive and accurate, and can accurately and quickly reflect the performance indicators of the DPP-type light source power, which is convenient for measuring the power indicators of the extreme ultraviolet light source.

[0027] 2. The DPP-type light source extreme ultraviolet light power measuring device and measuring method provided by the present application can accurately detect the monochromatic light power of the DPP-type light source by filtering the DPP-type light source through a filter to obtain monochromatic light, and the principle can be extended to the measurement of other monochromatic light. BRIEF DESCRIPTION OF DRAWINGS

[0028] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0029] Figure 1 Structure diagram of the discharge plasma type extreme ultraviolet light source power measuring device in an embodiment of the present application Figure 1 ;

[0030] Figure 2 Structure diagram of the discharge plasma type extreme ultraviolet light source power measuring device in an embodiment of the present application Figure 2 ;

[0031] Figure 3 Fig. 1 is a schematic diagram of a principle of a discharge plasma extreme ultraviolet light source power measuring device according to an embodiment of the present application;

[0032] Figure 4 Fig. 2 is a schematic diagram of Mo / Si multilayer mirror in-band filtering according to an embodiment of the present application;

[0033] Figure 5 Fig. 3 is an extreme ultraviolet photodiode response curve according to an embodiment of the present application;

[0034] Corresponding to the reference numerals: 1-xenon source, 2-control valve, 3-mass flow meter, 4-DPP light source, 5-first vacuum pump interface, 6-extendable vacuum pipeline, 7-first vacuum cavity, 8-filter clamping device, 9-second vacuum cavity, 10-mirror, 11-extreme ultraviolet photodiode, 12-photodiode clamping device, 13-current detection module, 14-mirror holder, 15-second vacuum pump interface. DETAILED DESCRIPTION

[0035] The present application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These are within the scope of the present application.

[0036] It should be noted that the terms "first", "second", etc. are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0037] At present, the extreme ultraviolet light power measurement of DPP light source is still blank. The spectral analysis and photodiode measurement of extreme ultraviolet light power are used to calculate the in-band light intensity ratio in the full spectrum of DPP light source, but this method has high requirements for spectral resolution and other performance, and it is difficult to ensure that the spectral analysis and photodiode measurement spectrum are synchronous, and the experimental platform is complicated and time-consuming. The present application embodiment proposes to obtain monochromatic light by filtering DPP light source through filter, and directly measure the power of the monochromatic light.

[0038] REFERENCE Figures 1-3The embodiment of the present application provides a kind of discharge plasma type extreme ultraviolet light source power measuring device.The device includes filter, mirror 10, extreme ultraviolet photodiode 11 and computing module etc., wherein: filter is used to carry out out-of-band filtering to the light of DPP type light source 4, forms filtered light beam;Filter is located between first vacuum cavity 7 and second vacuum cavity 9, first vacuum cavity 7 includes light source vacuum cavity, and second vacuum cavity 9 is communicated with first vacuum cavity 7;Mirror 10 is located in second vacuum cavity 9, mirror 10 is used to carry out in-band filtering to filtered light beam, forms in-band extreme ultraviolet light beam;Extreme ultraviolet photodiode 11 is located inside second vacuum cavity 9, and in-band extreme ultraviolet light beam is reflected to reach the detection plane of extreme ultraviolet photodiode 11, and extreme ultraviolet photodiode 11 is used to convert the light signal of in-band extreme ultraviolet light beam into current signal;Computing module is used to obtain the in-band extreme ultraviolet light power of DPP type light source 4 under specific solid angle according to current signal and the current-power response curve of extreme ultraviolet photodiode 11, and specific solid angle unit is spherical degree (sr);And the extreme ultraviolet light power of DPP type light source 4 is obtained according to the extreme ultraviolet light power of DPP type light source 4 under specific solid angle.

[0039] In the embodiment of the present application, DPP type light source 4 is the application object of the whole measuring device, and control valve 2 and mass flow meter 3 are arranged on the pipeline connected with xenon source 1.DPP type light source 4 generates ellipsoidal light beam in wide spectral band range from soft x-ray to infrared light through cathode discharge.The light of DPP type light source 4 is first filtered by filter, and the filtered light beam is in-band filtered by mirror 10, and is reflected to reach the detection plane of extreme ultraviolet photodiode 11.The above process is carried out in vacuum cavity.Finally, computing module calculates in-band extreme ultraviolet light power through the current-power response curve of photodiode.

[0040] Compared with the method for calculating the in-band light intensity ratio of extreme ultraviolet light power in the full spectral segment of DPP type light source, the embodiment of the present application does not need to maintain the synchronism of spectrometer and photodiode measurement spectrum, is easy to build experimental platform, has simple structure, and the used parts are easy to obtain, obtains monochromatic light through filtering DPP type light source 4, directly measures the power of the monochromatic light, thereby the extreme ultraviolet light power of DPP type light source 4 is obtained, the performance index of DPP type light source power can be accurately and quickly reflected, and the power index of extreme ultraviolet light source is easy to measure.

[0041] In order to realize filtering of the wide-band ellipsoidal light beam, in some embodiments, the filter is fixed inside the filter clamping device 8 and connected with the first vacuum cavity 7 and the second vacuum cavity 9 respectively, and the filter clamping device 8 is tightly matched with the first vacuum cavity 7 and the second vacuum cavity 9 through a sealing ring and a screw. According to the filtering requirement, it is necessary to filter as much as possible the spectrum band outside 1-20 nm or 5-20 nm, while ensuring high transmittance near 13.5 nm. The filter should have good in-band (13.5 nm 2% bandwidth) transmittance and provide a certain degree of out-of-band filtering. Although beryllium has good in-band transmittance and out-of-band filtering performance, its toxicity is too large; yttrium has good in-band transmittance, but it is easy to oxidize and ignite; silicon has good in-band transmittance, but the out-of-band filtering effect is limited. Preferably, the filter is a zirconium film filter, which has better in-band transmittance, and the spectral band range of the light beam obtained after filtering is 1-20 nm, thereby realizing out-of-band filtering.

[0042] The installation angle of the mirror 10 is determined according to the specific experimental device. In some embodiments, the mirror 10 is installed inside the second vacuum cavity 9 through the mirror frame 14, which is placed at an angle of 45 degrees relative to the filtered light beam axis, facilitating experimental measurement, and ensuring that the light beam after twice filtering can be reflected to the detection plane of the ultraviolet diode. In other embodiments, according to the specific structure of the mirror 10, 0 degrees or 90 degrees can also be set, as long as the same function can be realized.

[0043] In order to realize high reflectivity at the extreme ultraviolet band, in some embodiments, the mirror 10 is a Mo / Si multilayer film mirror, which includes periodically and alternately stacked Mo layers and Si layers. The Mo layers are first stacked on a mirror substrate, and then the Si layers are stacked. The Mo layers and the Si layers are stacked as one period, and this is repeated. The thickness of the Mo layer is 2.76 nm, and the thickness of the Si layer is 4.14 nm. The number of stacking and the setting of the stacking thickness ensure high reflectivity at 13.5 nm. The filtered light beam passes through the Mo / Si multilayer film mirror, AOI=45.0 deg, realizes high reflectivity at 13.5 nm, and can obtain the extreme ultraviolet spectral band distribution near 13.5 nm, as shown in FIG. 5. Figure 4

[0044] ​In the embodiment of the present application, the EUV photodiode 11 is fixed in the second vacuum cavity 9 by the photodiode clamping device 12. The in-band EUV light beam filtered by the out-of-band filter and the in-band filter is reflected on the detection plane of the EUV photodiode 11, and the light signal is converted into the current signal by the EUV photodiode 11. Specifically, the output current signal of the EUV photodiode 11 is measured by the current detection module 13 of the EUV photodiode 11. The current detection module 13 is exemplarily a multimeter or an oscilloscope. The power of the filtered in-band EUV light beam under a specific solid angle is calculated by the current-power response curve of the EUV photodiode 11, which is exemplarily shown in FIG. 8. Figure 5

[0045] In some embodiments, the calculation module obtains the specific solid angle of the in-band EUV light beam according to the distance DPP between the detector plane of the EUV photodiode 11 and the light source 4 and the size of the light-sensitive element of the EUV photodiode 11.

[0046] Since the EUV photodiode 11 can only receive part (specific solid angle) of the EUV light from the light source, it cannot represent the overall EUV light power of the light source, so it needs to be converted to 2π or 4π solid angle. Further, the calculation module integrates the EUV light power of the DPP light source 4 under the specific solid angle to obtain the EUV light power under the 2π or 4π solid angle, i.e., the EUV light power of the DPP light source. Specifically, taking the light source ellipsoidal light spot as the center and the distance from the light spot to the detector plane as the radius to make a spherical surface, which is a 4π solid angle, so as to convert the power under the specific solid angle to the 4π solid angle.

[0047] In some embodiments, the calculation module is further configured to unitize the EUV light power under the 4π solid angle to obtain the EUV light power of the DPP light source 4 under the unit solid angle, so as to represent the power index thereof.

[0048] In some embodiments, the above device further comprises a telescopic vacuum pipeline 6 connected with the DPP light source 4. The telescopic vacuum pipeline 6 is in communication with the light source vacuum cavity. The light source vacuum cavity is provided with a first vacuum pump interface 5 for connecting a vacuum pump. The first vacuum pump interface 5 is exemplarily connected with a vacuum molecular pump. The telescopic vacuum pipeline 6 and the internal space of the light source vacuum cavity form a first vacuum cavity 7. The second vacuum cavity 9 is provided with a second vacuum pump interface 15 for connecting a vacuum pump. The second vacuum pump interface 15 is exemplarily connected with a vacuum molecular pump. The vacuum molecular pump has the advantages of short starting time, high vacuum degree, high cleanliness, simple structure, small size, high efficiency, low noise, etc.

[0049] ​Based on the same inventive concept, another embodiment of the present application provides a method for measuring the power of a discharge plasma extreme ultraviolet light source, which is implemented by using the discharge plasma extreme ultraviolet light source power measuring device described above, and the method comprises the following steps:

[0050] S1, the DPP type light source 4 generates a wide spectrum ellipsoidal light beam from x-rays to infrared light, and the wide spectrum ellipsoidal light beam is filtered by the optical filter to form a filtered light beam;

[0051] S2, the filtered light beam is filtered by the mirror 10 to obtain an in-band extreme ultraviolet light beam;

[0052] S3, the in-band extreme ultraviolet light beam is reflected on the detection plane of the extreme ultraviolet photodiode 11, and the extreme ultraviolet photodiode 11 converts the light signal of the in-band extreme ultraviolet light beam into a current signal;

[0053] S4, according to the current signal and the current-power response curve of the extreme ultraviolet photodiode 11, the in-band extreme ultraviolet light power of the DPP type light source 4 under a specific solid angle is obtained;

[0054] S5, according to the extreme ultraviolet light power of the DPP type light source 4 under a specific solid angle, the extreme ultraviolet light power of the DPP type light source 4 is obtained.

[0055] The DPP type light source extreme ultraviolet light power measuring device and the measuring method provided by the above embodiments of the present application can obtain monochromatic light after filtering the DPP type light source by the optical filter, and the principle can be extended to the measurement of other monochromatic light, and the monochromatic light power of the DPP type light source can be accurately detected.

[0056] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the present application. The above preferred features can be combined for use in the case of not conflicting with each other.

Claims

1. A discharge plasma type extreme ultraviolet light source power measuring device, characterized by comprising: a light source; a light receiving element; a light source power measuring device; and a light source power measuring device control unit. The device comprises: a filter for filtering the light emitted by the DPP light source out of band to form a filtered light beam; the filter is located between the first vacuum cavity and the second vacuum cavity, the first vacuum cavity comprises a light source vacuum cavity, and the second vacuum cavity is in communication with the first vacuum cavity; a mirror located in the second vacuum cavity, the mirror is used for filtering the filtered light beam in band to form an in-band extreme ultraviolet light beam; an extreme ultraviolet photodiode located in the second vacuum cavity, the in-band extreme ultraviolet light beam is reflected to the detection plane of the extreme ultraviolet photodiode, and the extreme ultraviolet photodiode is used for converting the optical signal of the in-band extreme ultraviolet light beam into an electric current signal; a calculation module for obtaining the in-band extreme ultraviolet light power of the DPP light source under a specific solid angle according to the electric current signal and the current-power response curve of the extreme ultraviolet photodiode, and obtaining the extreme ultraviolet light power of the DPP light source according to the extreme ultraviolet light power of the DPP light source under the specific solid angle.

2. The apparatus according to claim 1, wherein The filter is a zirconium film filter, and the spectral range of the filtered light beam is 1-20 nm.

3. The apparatus according to claim 1, wherein The mirror is placed at an angle of 45 degrees relative to the axis of the filtered light beam.

4. The apparatus according to claim 1, wherein The mirror is a Mo / Si multilayer film mirror, which comprises Mo layers and Si layers stacked alternately in cycles, wherein the thickness of the Mo layer is 2.76 nm, and the thickness of the Si layer is 4.14 nm.

5. The apparatus according to claim 1, wherein The calculation module obtains the specific solid angle of the in-band extreme ultraviolet light beam according to the distance between the detector plane of the extreme ultraviolet photodiode and the DPP light source and the size of the photosensitive element of the extreme ultraviolet photodiode.

6. The apparatus according to claim 5, wherein The calculation module integrates the extreme ultraviolet light power of the DPP light source under the specific solid angle to obtain the extreme ultraviolet light power under a 2π or 4π solid angle, i.e. the extreme ultraviolet light power of the DPP light source.

7. The apparatus according to claim 6, wherein The calculation module is also used for unitizing the extreme ultraviolet light power under a 4π solid angle to obtain the extreme ultraviolet light power of the DPP light source under a unit solid angle.

8. The apparatus according to claim 1, wherein The device further comprises a telescopic vacuum pipeline connected with the DPP light source, the telescopic vacuum pipeline is in communication with the light source vacuum cavity, a first vacuum pump interface for connecting a vacuum pump is arranged on the light source vacuum cavity, the telescopic vacuum pipeline and the internal space of the light source vacuum cavity form the first vacuum cavity, and a second vacuum pump interface for connecting a vacuum pump is arranged on the shell of the second vacuum cavity.

9. The apparatus according to claim 1, wherein The filter is fixed between the first vacuum cavity and the second vacuum cavity by a filter clamping device, and the extreme ultraviolet photodiode is fixed in the interior of the second vacuum cavity by a photodiode clamping device.

10. A method of measuring the power of a discharge plasma extreme ultraviolet light source, using the measuring device of any one of claims 1 to 9, characterized in that, The device comprises: A DPP light source generates a wide-spectrum ellipsoidal light beam from x-rays to infrared light, the wide-spectrum ellipsoidal light beam is filtered out of band by a filter to form a filtered light beam; The filtered light beam is filtered in band by a mirror to obtain an in-band extreme ultraviolet light beam; The in-band extreme ultraviolet light beam is reflected on the detection plane of an extreme ultraviolet photodiode, and the extreme ultraviolet photodiode converts the optical signal of the in-band extreme ultraviolet light beam into an electric current signal; According to the current signal and the current-power response curve of the extreme ultraviolet photodiode, the in-band extreme ultraviolet light power of the DPP type light source under a specific solid angle is obtained; According to the extreme ultraviolet light power of the DPP type light source under a specific solid angle, the extreme ultraviolet light power of the DPP type light source is obtained.

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