CN111913370A - Extreme ultraviolet light generating method and device - Google Patents
Extreme ultraviolet light generating method and device Download PDFInfo
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- CN111913370A CN111913370A CN202010875810.7A CN202010875810A CN111913370A CN 111913370 A CN111913370 A CN 111913370A CN 202010875810 A CN202010875810 A CN 202010875810A CN 111913370 A CN111913370 A CN 111913370A
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- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
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Abstract
The application relates to an extreme ultraviolet light generating method and device, wherein the method comprises the following steps: generating a target material droplet string along a droplet direction in a vacuum environment; generating high-power laser with the frequency matched with that of the target material droplet string; and focusing the high-power laser and then reversely striking the dripped target material droplet string along the dripping direction so as to enable the target material droplet to be subjected to the laser action opposite to the dripping direction and to be converted into plasma, thereby generating extreme ultraviolet light. An extreme ultraviolet light generating device comprises a target material droplet generator, a high-power laser light source device and a focusing lens. The invention uses a set of high-power laser light source device, generates the required extreme ultraviolet light by one-time target shooting, has simple device and convenient equipment debugging and maintenance, and is beneficial to reducing the cost.
Description
Technical Field
The present disclosure relates to the field of Extreme Ultraviolet (EUV) light source technology, and more particularly, to a method and an apparatus for generating EUV light.
Background
With the increasing requirements of the microelectronic field on the processing technology, Deep ultraviolet (Deep-Violet, DUV) lithography of the traditional excimer laser cannot meet the development of the chip industry under the promotion of moore's law, and an Extreme Ultraviolet (EUV) light source is generated at the same time. The current solution for large-scale industrial production is mainly LPP (Laser Produced Plasma), i.e. high-power Laser is used to laterally hit target droplets to generate EUV light with a wavelength of 13.5 nm.
However, the traditional extreme ultraviolet light generation method hits liquid drops from the side surface, is limited by the drop time of the liquid drops, has the problem of short laser action time, and is not beneficial to improving the utilization rate of high-power laser.
Disclosure of Invention
In view of the above, there is a need to provide a new extreme ultraviolet light generating method and apparatus to overcome the deficiencies of the prior art.
A method of extreme ultraviolet light generation, comprising:
generating a target material droplet string along a droplet direction in a vacuum environment;
generating high-power laser with the frequency matched with that of the target material droplet string;
and focusing the high-power laser and then reversely striking the dripped target material droplet string along the dripping direction so as to enable the target material droplet to be subjected to the laser action opposite to the dripping direction and to be converted into plasma, thereby generating extreme ultraviolet light.
In one embodiment, the frequency of the target droplet train is matched to the high power laser frequency, including:
the frequency of the target material droplet string is the same as the high-power laser frequency.
In one embodiment, the frequency of the target droplet train is matched to the high power laser frequency, including:
the frequency of the target material droplet string is an integral multiple of the high-power laser frequency.
In one embodiment, the frequency of the target droplet train is matched to the high power laser frequency, including:
the frequency of the target material droplet string is an integral fraction of the high-power laser frequency.
In one embodiment, the high power laser is a high power laser, and the focused high power laser strikes the dripped target droplet string in a reverse direction along a dripping direction to make the target droplet under the action of the laser in a direction opposite to the dripping direction and converted into plasma, thereby generating extreme ultraviolet light, including:
focusing the high-power laser on a focus position, and striking the target material liquid drop meeting the high-power laser along the direction opposite to the dropping direction so that the target material liquid drop is subjected to the laser action opposite to the dropping direction and is converted into plasma, thereby generating extreme ultraviolet light.
In one embodiment, the high-power laser is a multi-channel high-power laser, and the focused high-power laser strikes the dripped target droplet string in a reverse direction along a dripping direction to make the target droplet under the action of the laser in a direction opposite to the dripping direction and converted into plasma, thereby generating extreme ultraviolet light, including:
and focusing the multi-path high-power laser on the same focus position in the direction of the symmetrical axis array distribution with the dropping direction of the target material liquid drop, and striking the target material liquid drop meeting the multi-path high-power laser, so that the target material liquid drop is subjected to the laser action opposite to the dropping direction and is converted into plasma, and extreme ultraviolet light is generated.
In one embodiment, after focusing the high-power laser and striking the dropped target droplet string in a direction opposite to the dropping direction, the target droplet is subjected to a laser action opposite to the dropping direction and is turned into a plasma, so as to generate extreme ultraviolet light, the method further includes:
the plasmatized target droplets are removed.
In one embodiment, the method for removing a droplet of target material that is plasmatized comprises: a drive is provided to move the plasma-formed target droplets away from the strike path.
An extreme ultraviolet light generating device comprises a target material droplet generator, a high-power laser light source device and a focusing lens,
the target material liquid drop generator is used for generating a target material liquid drop string along a dropping direction in a vacuum environment;
the high-power laser device is used for generating high-power laser and transmitting the laser to the focusing lens;
the focusing lens is used for focusing the high-power laser in a vacuum environment, and reversely striking the dripped target material droplet string along the dripping direction, so that the target material droplet is subjected to the laser action opposite to the dripping direction and is converted into plasma, and extreme ultraviolet light is generated.
In one embodiment, a drive means is included for moving the plasma-formed target droplets away from the strike path.
According to the extreme ultraviolet light generating method and device, high-power laser is generated through a high-power laser light source, a target material liquid drop string with the frequency matched with the high-power laser frequency is generated in a vacuum environment through a target material liquid drop generator along the dropping direction, the high-power laser is focused in the vacuum environment through a focusing lens, and the dropped target material liquid drop string is hit reversely along the dropping direction, so that the target material liquid drop is subjected to the laser action opposite to the dropping direction and is converted into plasma, and extreme ultraviolet light is generated. The target material liquid drop that this application medium and high power laser hit along the drippage direction is backward to be dripped, makes its effort and the target material liquid drop drippage direction opposite to the target material liquid drop, is favorable to increasing the action time of high power laser, improves the utilization ratio of high power laser. .
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow diagram of a method for extreme ultraviolet light generation in one embodiment;
fig. 2 is a schematic structural diagram of an extreme ultraviolet light generating device provided in an embodiment;
fig. 3 is a schematic structural diagram of an extreme ultraviolet light generating device provided in another embodiment;
FIG. 4 is a schematic diagram showing the relative positions of a plurality of high power laser light source devices and a plurality of focusing lenses in the embodiment of FIG. 3;
FIG. 5 is a flow chart of a method for generating extreme ultraviolet light in another embodiment.
Description of reference numerals: 101-target droplet generator, 102-vacuum environment, 103-high power laser light source device, 104-high power laser, 105-focusing lens, 106-target droplet string, 107-focusing lens focus, 108-extreme ultraviolet light, 2031-first high power laser light source device, 2041-first high power laser, 2051-first focusing lens, 2032-second high power laser light source device, 2042-second high power laser, 2052-second focusing lens, 2033-third high power laser light source device, 2043-third high power laser, 2053-third focusing lens, 2034-fourth high power laser light source device, 2044-fourth high power laser, 2054-fourth focusing lens.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.
It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be connected to the other element through intervening elements. In addition, "connection" in the following embodiments is understood as "optical connection" if there is transmission of an optical signal between connected objects.
In one embodiment, there is provided an extreme ultraviolet light generating method, as shown in fig. 1, the method including:
step S11: a train of target droplets is generated in a vacuum environment along a droplet landing direction.
Specifically, the vacuum environment may be a vacuum chamber, and a vacuum pump is used to pump air out of the chamber to ensure the vacuum degree. The specific generation process of the target droplet string may be: the target is heated to a temperature higher than the melting point, and then the target droplets are sprayed out from a nozzle through a filter by applying pressure, so that a target droplet string with uniform size and stable frequency is generated. Preferably, the target droplets are metal droplets, such as tin; the diameter of the target liquid drop is 50-70 microns, and the frequency of the target liquid drop string is 50-500 kHz. The dripping direction refers to the movement direction of the target material liquid drops after being separated from the target material liquid drop generator, and can be accelerated dripping movement under the action of gravity or constant-speed dripping movement kept along the original spraying direction under the condition of zero gravity. For ease of understanding, the following description will be given by way of example of a target droplet train accelerated by gravity to fall vertically downwards.
Step S12: a high power laser is generated with a frequency matching the frequency of the target droplet train.
High power lasers generally refer to lasers with powers greater than 1000 watts. The matching of the target material droplet string frequency and the high-power laser frequency means that one high-power laser pulse correspondingly acts on one target material droplet. The high-power laser device generates high-power laser matched with the frequency of the target droplet string, namely before the extreme ultraviolet light generating device works, parameter setting is respectively carried out on the target droplet generator and the high-power laser device in the high-power laser device, so that the frequency of the target droplet string is matched with the frequency of the high-power laser device, or the frequency of one instrument is kept unchanged, and the frequency of the other instrument is matched with the frequency of the high-power laser device by setting the frequency of the other instrument. Specifically, the drop frequency of the target droplet string may be modulated by a mechanical vibration modulator in the target droplet generator, and the high power laser frequency may be set by a repetition rate parameter of the high power laser.
Step S13; the high-power laser is focused and then reversely strikes the dripped target material droplet string along the dripping direction, so that the target material droplet is subjected to the laser action opposite to the dripping direction and is converted into plasma, and then extreme ultraviolet light is generated.
It is noted that in this application, the beating is not a beating action in the conventional sense, but rather a whole process in which high power laser pulses are applied to the target droplets to cause them to change. Specifically, focusing the high-power laser and then hitting the dropped target droplet string in the opposite direction along the dropping direction means that: focusing the high-power laser at the focus of the focusing lens by using the focusing lens to form a high-power laser energy field taking the focus as the center, and adjusting the position and the angle of the focusing lens to enable the focus of the focusing lens to be on a target material dropping route; the high-power laser pulses of each path simultaneously reach the focus of the focusing lens by carrying out time sequence control on the high-power laser light sources of each path; and setting the dropping start time of the target material liquid drop string to ensure that the target material liquid drop meets the high-power laser pulse at the focus of the focusing lens. The high-power laser is focused by the focusing lens and acts on the target material liquid drop, so that the target material liquid drop is subjected to the laser action opposite to the dropping direction. The specific process of making target material liquid drop into plasma body and further producing extreme ultraviolet light is as follows: the target material liquid drop reaching the high-power laser energy field deforms into a flat shape under the mutual influence of gravity and laser action, and the volume of the target material liquid drop is increased; the flattened target material liquid drop is continuously subjected to laser action to be plasmatized, and when the threshold value of generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light is generated.
According to the extreme ultraviolet light generating method, the required extreme ultraviolet light is generated by one-time target shooting, only one set of high-power laser light source device is needed in the whole process, the device is simple, the equipment is convenient to debug and maintain, and the cost is reduced; by reasonably designing the transmission direction of the high-power laser, the acting force of the high-power laser on the target material liquid drop is opposite to the dropping direction of the target material liquid drop, the acting time of the high-power laser is prolonged, and the utilization rate of the high-power laser is improved; the target material liquid drop is promoted to generate flat deformation, the size is increased, the flat forming uniformity of the plasma is improved, and the energy conversion efficiency of the system is improved. In one embodiment, with continued reference to fig. 1, in step S12, the frequency of the target droplet train is matched to the high power laser frequency by: the frequency of the target material droplet and the target material droplet string is the same as the high-power laser frequency. Each focused high-power laser pulse correspondingly acts on one target material liquid drop, and each target material liquid drop is struck by the corresponding high-power laser pulse to enable the target material liquid drop to be plasma-shaped, so that extreme ultraviolet light is generated.
Through parameter setting, the frequency of the target material droplet string is the same as the high-power laser frequency, each high-power laser pulse can be guaranteed to act on one target material droplet correspondingly, each target material droplet is hit by the corresponding high-power laser pulse, the utilization rate of high-power laser is improved, and meanwhile waste of the target material droplets is avoided.
In one embodiment, with continued reference to fig. 1, in step S12, the frequency of the target droplet train is matched to the high power laser frequency by: the frequency of the target material liquid drop string is integral multiple of the high-power laser frequency. One focused high-power laser pulse strikes one target material liquid drop to enable the target material liquid drop to be plasma-formed, and then after extreme ultraviolet light is generated, the target material liquid drop with a fixed number leaks through until the next focused high-power laser pulse reaches and strikes the target material liquid drop meeting the target material liquid drop, the target material liquid drop is plasma-formed, and then the extreme ultraviolet light is generated.
In this embodiment, through parameter setting, the frequency of the target droplet string is an integral multiple of the high-power laser frequency, which can ensure that each high-power laser pulse correspondingly acts on one target droplet, and is beneficial to improving the utilization rate of high-power laser.
In one embodiment, with continued reference to fig. 1, in step S12, the frequency of the target droplet train is matched to the high power laser frequency by: the frequency of the target droplet string is an integral fraction of the high power laser frequency. A focused high-power laser pulse strikes a target material liquid drop to enable the target material liquid drop to be plasma-converted, and then after extreme ultraviolet light is generated, the high-power laser pulse with a fixed number leaks until the next target material liquid drop meets the high-power laser pulse, and the plasma-converted liquid drop is sent under the action force of the high-power laser pulse to generate the extreme ultraviolet light.
In this embodiment, through parameter setting, the frequency of the target droplet string is an integral fraction of the high power laser frequency, which can ensure that each target droplet is acted by a corresponding high power laser pulse, and is beneficial to avoiding the waste of target droplets.
Therefore, a matching mode of frequency parameters of various high-power lasers and target droplet generators is provided, and the flexibility of the application scene of the extreme ultraviolet light generation method is improved.
In an embodiment, with reference to fig. 1, the high-power laser is a high-power laser, and step S13 is performed by focusing the high-power laser and striking the dropped target droplet string in a direction opposite to the dropping direction, so that the target droplet is subjected to the laser action opposite to the dropping direction and turned into plasma, thereby generating extreme ultraviolet light, where the step is: focusing one path of high-power laser on a focus position, and striking the target material liquid drop meeting the high-power laser along the opposite direction of the dropping direction so that the target material liquid drop is acted by the laser in the opposite direction of the dropping direction and is converted into plasma, thereby generating the extreme ultraviolet light.
Specifically, as shown in fig. 2, in a vacuum environment, the target droplet generator 101 generates a target droplet string 106 that drops in a vertical direction. A high power laser light source device 103 is placed on the opposite side of the target droplet generator 101, the high power laser light source device 103 comprising a high power laser and a beam delivery device. The high-power laser 104 generated by the high-power laser passes through the beam transmission device and reaches the focusing lens 105, and is focused at the focal point 107 of the focusing lens to form a high-power laser energy field centered on the focal point. The high-power laser 104 and the target droplet string 106 are oppositely transmitted after passing through the focusing lens 105 by adjusting the positions and angles of the beam transmission device and the focusing lens 105; each path of high-power laser pulse simultaneously reaches the focus 107 of the focusing lens by carrying out time sequence control on each path of high-power laser light source; the drop start time of the target droplet train 106 is set such that the target droplet meets the high power laser pulse at the focal point 107 of the focusing lens. The liquid drops reach the high-power laser energy field target material and deform into a cake shape under the mutual influence of gravity and laser action, so that the volume is increased; the target material liquid drop after cake-shaped molding continues to move towards the center of the high-power laser energy field, namely the focus 107 of the focusing lens, the flattened target material liquid drop continues to be plasmatized under the action of laser, and when the threshold value of generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light 108 is generated.
In the embodiment, by designing the dropping direction of the target material droplet string and the transmission direction of the high-power laser, the acting force of the high-power laser on the target material droplet is opposite to the gravity direction of the target material droplet, the acting time of the high-power laser is prolonged, and the utilization rate of the high-power laser is improved; the target material liquid drop is promoted to generate pie-shaped deformation, the size is increased, the uniformity of plasma pie-shaped forming is improved, better extreme ultraviolet radiation is generated, and the energy conversion efficiency of the system is improved.
In one embodiment, the high power laser is a multi-channel high power laser formed by splitting one high power laser generated by one high power laser through a beam transmission device, and referring to fig. 1, step S13, the high power laser is focused and then strikes the dropped target droplet string in a reverse direction along the dropping direction, so that the target droplet is acted by the laser in a direction opposite to the dropping direction and is converted into plasma, thereby generating extreme ultraviolet light, which means: the multi-path high-power laser is focused at the same focus position in the direction of the symmetrical axis array distribution with the dropping direction of the target material liquid drops, and the target material liquid drops meeting the multi-path high-power laser are hit, so that the target material liquid drops are subjected to the action of the laser opposite to the dropping direction and are converted into plasma, and extreme ultraviolet light is generated. Specifically, the high-power laser generated by the high-power laser can be split by the beam splitter or the beam splitter, and then the transmission direction of each path of split high-power laser is changed by arranging optical elements such as a reflector and the like, so that each path of high-power laser can accurately reach a preset focusing lens which is distributed along the target dropping direction and is taken as a symmetry axis array.
In the embodiment, one path of high-power laser is split to form multiple paths of high-power laser, and then the multiple paths of high-power laser are focused and hit target material liquid drops meeting the high-power laser, so that the hitting directions of the multiple paths of laser can be designed according to actual conditions, the target material liquid drops are subjected to plasma change, required extreme ultraviolet light is generated, and the flexibility of the application scene of the extreme ultraviolet light generation method is favorably improved.
In one embodiment, with reference to fig. 1, the high power laser is a plurality of high power lasers generated by a plurality of high power laser devices, and step S13 is performed by focusing the high power laser and then striking the dropped target droplet string in a direction opposite to the dropping direction, so that the target droplet is subjected to the laser action in the direction opposite to the dropping direction and is converted into plasma, thereby generating extreme ultraviolet light, where: the multi-path high-power laser is focused at the same focus position in the direction of the symmetrical axis array distribution with the dropping direction of the target material liquid drops, and the target material liquid drops meeting the multi-path high-power laser are hit, so that the target material liquid drops are subjected to the action of the laser opposite to the dropping direction and are converted into plasma, and extreme ultraviolet light is generated.
Specifically, as shown in fig. 3, the plurality of focusing lenses are distributed below the target droplet generator in an array with the target droplet landing direction as a symmetry axis, and connected to the corresponding multi-channel high-power laser light source devices to focus the multi-channel high-power laser light generated by the multi-channel high-power laser device on the same focal point. The parameters of each high-power laser device are the same, and the parameters of each focusing lens are also the same. Fig. 4 is a schematic diagram of relative positions of the plurality of high-power laser light source devices and the plurality of focusing lenses in fig. 3, wherein the diagram shows the dropping direction of the target droplet string. As shown in fig. 4, the plurality of focusing lenses are distributed below the target droplet generator in an array with the landing direction of the target droplet string as a symmetry axis, and are connected to the corresponding multi-channel high-power laser source devices to focus the multi-channel high-power laser generated by the multi-channel high-power laser device on the same focal point 107, so as to form a high-power laser energy field with the focal point as the center. Each path of high-power laser pulse simultaneously reaches the focus 107 of the focusing lens by carrying out time sequence control on each path of high-power laser light source; the drop start time of the target droplet train 106 is set such that the target droplet meets the high power laser pulse at the focal point 107 of the focusing lens. The target material liquid drops reach the high-power laser energy field, are deformed into a flat shape under the mutual influence of gravity and laser action under the action of laser opposite to the dropping direction, and the volume is increased; the flattened target droplets continue to move towards the center of the high-power laser energy field, i.e. the focus 107 of the focusing lens, the flattened target droplets continue to be plasmatized under the action of laser, and when the threshold for generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light 108 is generated.
In this embodiment, multiple high-power lasers generated by multiple high-power laser light source devices are focused on the same focus to hit the target droplets meeting the high-power lasers, so that in practical application, when the output energy of one high-power laser is insufficient, the number of the high-power lasers is properly increased, and the hitting directions of the high-power lasers are reasonably designed, so that the target droplets are subjected to plasma change, and further required extreme ultraviolet light is generated.
Therefore, the matching modes of various high-power laser devices are provided, and the flexibility of the application scene of the extreme ultraviolet light generation method is favorably improved.
In one embodiment, as shown in FIG. 2, after step S13, the method further includes step S14.
Step S14: the plasmatized target droplets are removed.
The plasma target material liquid drops have certain residues after being radiated by extreme ultraviolet light, and the step of removing the plasma target material liquid drops refers to the step of removing the residual target material liquid drops to enable the residual target material liquid drops to be separated from a high-power laser energy field near the focus of the focusing lens.
In one embodiment, with continued reference to fig. 2, step S14, the method of removing the plasmatized target droplets is: a drive is provided to move the plasma-formed target droplets away from the strike path. The driving may be an external magnetic field, trapping the metal target droplets that are plasmatized. When the frequency of the target droplet string is an integral multiple of the high power laser frequency, the drive is also used to process target droplets that arrive at the focal position in the interval of two laser pulses but are not acted on by the laser, leaving the strike path before the next laser pulse arrives.
In this embodiment, after the target droplets subjected to the plasmatization radiate the extreme ultraviolet light, the extreme ultraviolet light is removed from the high-power laser energy field, so that the residues are prevented from absorbing the high-power laser energy, the utilization rate of the high-power laser is also improved, and the energy conversion efficiency of the system is improved.
Further, in the vacuum chamber, the target droplet generator generates a metal target droplet string with a diameter of 40 microns which is dripped along the vertical direction, and the dripping frequency of the target droplet string is the same as the high-power laser frequency by adjusting the parameters of the target droplet generator, and the frequencies of the two are both 200 kHz. The high-power laser light source device is arranged on one side opposite to the target material droplet generator and comprises a high-power laser and a light beam transmission device. The high-power laser generated by the high-power laser passes through the light beam transmission device and then reaches the focusing lens, and is focused at the focal point of the focusing lens to form a high-power laser energy field taking the focal point as the center. The high-power laser and the target material liquid drop string are transmitted oppositely after passing through the focusing lens by adjusting the positions and angles of the beam transmission device and the focusing lens; the high-power laser pulses of each path simultaneously reach the focus of the focusing lens by carrying out time sequence control on the high-power laser light sources of each path; and setting the dropping start time of the target material liquid drop string to ensure that the target material liquid drop meets the high-power laser pulse at the focus of the focusing lens. The liquid drops reach the high-power laser energy field target material and deform into a cake shape under the mutual influence of gravity and laser action, so that the volume is increased; the target material liquid drop after cake-shaped forming continuously moves to the center of the high-power laser energy field, namely the focus of the focusing lens, the flattened target material liquid drop is continuously subjected to laser action to be plasmatized, and when the threshold value for generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light is generated. And providing an external magnetic field to capture the metal target droplets turned into plasma, so that the target droplets turned into plasma leave the striking route. The vacuum cavity is also provided with a collecting mirror for collecting the extreme ultraviolet light radiated by the target material liquid drops. The focusing lens is arranged at a proper position apart from the bombardment center and the light path between the reflectors, so that the energy of the laser is ensured to be concentrated as much as possible when bombarding the target material liquid drop.
In this embodiment, through parameter setting, the frequency of the target droplet string is the same as the frequency of the high-power laser, which is beneficial to improving the utilization rate of the high-power laser and avoiding the waste of the target droplets. By designing the dropping direction of the target material droplet string and the transmission direction of the high-power laser, the acting force of the high-power laser on the target material droplet is opposite to the self gravity direction of the target material droplet, the acting time of the high-power laser is prolonged, and the utilization rate of the high-power laser is improved; the target material liquid drop is promoted to generate pie-shaped deformation, the size is increased, the uniformity of plasma pie-shaped forming is improved, better extreme ultraviolet radiation is generated, and the energy conversion efficiency of the system is improved. After the target material liquid drops subjected to plasma processing radiate extreme ultraviolet light, the target material liquid drops are moved out of the high-power laser energy field, so that the high-power laser energy is prevented from being absorbed by the residues, the utilization rate of the high-power laser is improved, and the energy conversion efficiency of the system is improved.
It should be understood that although the steps in the flowcharts of fig. 1 and 5 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1 and 5 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least some of the other steps.
In one embodiment, an extreme ultraviolet light generating apparatus is provided, as shown in fig. 2, the apparatus comprising a target droplet generator 101, a high power laser light source apparatus 103, and a focusing lens 105. The target droplet generator 101 is fixed in a vacuum environment 102, the vacuum environment 102 may be a vacuum chamber, and the target droplet generator 101 may be fixed on a chamber wall of the vacuum chamber to generate a target droplet string 106 with uniform size and stable frequency along a dropping direction. The high-power laser light source device 103 includes a high-power laser and a light beam transmission device, wherein the high-power laser may be a fiber laser, or may be other types of lasers such as a solid laser or a semiconductor laser. The high power laser is connected to the focusing lens 105 by a beam delivery device for generating high power laser light 104 matched to the frequency of the target droplet train 106, and delivering the high power laser light 104 to the focusing lens 105. A focusing lens 105 is mounted in the vacuum environment 102 by a frame and is used to focus the high power laser 104 at a focusing lens focal point 107 in the vacuum environment 102 to form a high power laser energy field centered at the focal point. By adjusting the position and angle of the focusing lens 105, the focusing lens focus 107 can be made on the target landing path. The high-power laser pulses of each path simultaneously reach the focus 107 of the focusing lens by carrying out time sequence control on the high-power laser light sources of each path; the drop start time of the target droplet train 106 is set such that the target droplet meets the high power laser pulse at the focal point 107 of the focusing lens. The target material liquid drops reaching the high-power laser energy field are deformed into a cake shape under the mutual influence of gravity and laser action under the action of laser opposite to the dropping direction, and the volume is increased; the pie-shaped target material droplets continue to move towards the center of the high-power laser energy field, i.e. the focal point 107 of the focusing lens, the pie-shaped target material droplets continue to be plasmatized under the action of the laser, and when the threshold value for generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light 108 is generated.
The extreme ultraviolet light generating device uses a set of high-power laser light source device, generates the required extreme ultraviolet light by one-time target shooting, has simple device and convenient equipment debugging and maintenance, and is beneficial to reducing the cost; by reasonably designing the transmission direction of the high-power laser, the acting force of the high-power laser on the target material liquid drop is opposite to the dropping direction of the target material liquid drop, the acting time of the high-power laser is prolonged, and the utilization rate of the high-power laser is improved; the target material liquid drop is promoted to generate pie-shaped deformation, the size is increased, the uniformity of plasma pie-shaped forming is improved, better extreme ultraviolet radiation is generated, and the energy conversion efficiency of the system is improved.
In one embodiment, an euv light generating apparatus is provided, as shown in fig. 3 and 4, the apparatus includes a target droplet generator 101, a first high-power laser light source device 2031, a first focusing lens 2051, a second high-power laser light source device 2032, a second focusing lens 2052, a third high-power laser light source device 2033, a third focusing lens 2053, a fourth high-power laser light source device 2034, and a fourth focusing lens 2054. The target droplet generator 101 is fixed in a vacuum environment 102, the vacuum environment 102 may be a vacuum chamber, and the target droplet generator 101 may be fixed on a chamber wall of the vacuum chamber to generate a target droplet string 106 with uniform size and stable frequency along a dropping direction. The high-power laser light source devices are respectively connected with the corresponding focusing lenses to accurately transmit the multi-path high-power laser to the focusing lenses. The plurality of focusing lenses are distributed on the opposite side of the target droplet generator 101 in an array with the dropping direction of the target droplet string as a symmetry axis, and focus the plurality of paths of high-power laser at the same focus position to form a high-power laser energy field with the focus as the center. Each path of high-power laser pulse simultaneously reaches the focus 107 of the focusing lens by carrying out time sequence control on each path of high-power laser light source; the drop start time of the target droplet train 106 is set such that the target droplet meets the high power laser pulse at the focal point 107 of the focusing lens. The target material liquid drops reach the high-power laser energy field, are deformed into a flat shape under the mutual influence of gravity and laser action under the action of laser opposite to the dropping direction, and the volume is increased; the flattened target droplets continue to move towards the center of the high-power laser energy field, i.e. the focus 107 of the focusing lens, the flattened target droplets continue to be plasmatized under the action of laser, and when the threshold for generating extreme ultraviolet radiation is reached, the required extreme ultraviolet light 108 is generated.
In this embodiment, multiple high-power lasers generated by multiple high-power laser light source devices are focused on the same focus to hit the target droplets meeting the high-power lasers, so that in practical application, when the output energy of one high-power laser is insufficient, the number of the high-power lasers is properly increased, and the hitting directions of the high-power lasers are reasonably designed, so that the target droplets are subjected to plasma change, and further required extreme ultraviolet light is generated.
Therefore, the matching modes of various high-power laser devices are provided, and the flexibility of the application scene of the extreme ultraviolet light generation method is favorably improved.
In one embodiment, the extreme ultraviolet light generating device further comprises a driving device installed in a vacuum environment and used for driving the target material drops which are plasmatized to leave the striking route. The driving may be an external magnetic field, trapping the metal target droplets that are plasmatized. When the frequency of the target droplet string is an integral multiple of the high power laser frequency, the drive is also used to process target droplets that arrive at the focal position in the interval of two laser pulses but are not acted on by the laser, leaving the strike path before the next laser pulse arrives.
In this embodiment, after the target droplets subjected to the plasmatization radiate the extreme ultraviolet light, the extreme ultraviolet light is removed from the high-power laser energy field, so that the residues are prevented from absorbing the high-power laser energy, the utilization rate of the high-power laser is also improved, and the energy conversion efficiency of the system is improved.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method of producing extreme ultraviolet light, comprising:
generating a target material droplet string along a droplet direction in a vacuum environment;
generating high-power laser with the frequency matched with that of the target material droplet string;
and focusing the high-power laser and then reversely striking the dripped target material droplet string along the dripping direction so as to enable the target material droplet to be subjected to the laser action opposite to the dripping direction and to be converted into plasma, thereby generating extreme ultraviolet light.
2. The extreme ultraviolet light generating method of claim 1, wherein the frequency of the target droplet train is matched to the high power laser frequency, comprising:
the frequency of the target material droplet string is the same as the high-power laser frequency.
3. The extreme ultraviolet light generating method of claim 1, wherein the frequency of the target droplet train is matched to the high power laser frequency, comprising:
the frequency of the target material droplet string is an integral multiple of the high-power laser frequency.
4. The extreme ultraviolet light generating method of claim 1, wherein the frequency of the target droplet train is matched to the high power laser frequency, comprising:
the frequency of the target material droplet string is an integral fraction of the high-power laser frequency.
5. The method of claim 1, wherein the high power laser is a path of high power laser, and the focusing of the high power laser strikes the dropped target droplet string in a reverse direction along a dropping direction, so that the target droplet is subjected to a laser action in a direction opposite to the dropping direction and is plasmatized to generate the extreme ultraviolet light, comprising:
focusing the high-power laser on a focus position, and striking the target material liquid drop meeting the high-power laser along the direction opposite to the dropping direction so that the target material liquid drop is subjected to the laser action opposite to the dropping direction and is converted into plasma, thereby generating extreme ultraviolet light.
6. The method of claim 1, wherein the high power laser is a multi-channel high power laser, and the focusing the high power laser strikes the dropped target droplet string in a reverse direction along a dropping direction, so that the target droplet is affected by the laser in a direction opposite to the dropping direction and is plasmatized to generate the extreme ultraviolet light, comprising:
and focusing the multi-path high-power laser on the same focus position in the direction of the symmetrical axis array distribution with the dropping direction of the target material liquid drop, and striking the target material liquid drop meeting the multi-path high-power laser, so that the target material liquid drop is subjected to the laser action opposite to the dropping direction and is converted into plasma, and extreme ultraviolet light is generated.
7. The method of claim 1, wherein the focusing the high power laser light strikes the dropped target droplet string in a direction opposite to a dropping direction, so that the target droplet is exposed to the laser light in the direction opposite to the dropping direction and is converted into plasma, thereby generating the extreme ultraviolet light, further comprising:
the plasmatized target droplets are removed.
8. The method of claim 7, wherein the step of removing the plasmatized droplets of target material comprises: a drive is provided to move the plasma-formed target droplets away from the strike path.
9. An extreme ultraviolet light generating device is characterized by comprising a target material droplet generator, a high-power laser light source device and a focusing lens,
the target material liquid drop generator is used for generating a target material liquid drop string along a dropping direction in a vacuum environment;
the high-power laser device is used for generating high-power laser and transmitting the laser to the focusing lens;
the focusing lens is used for focusing the high-power laser in a vacuum environment, and reversely striking the dripped target material droplet string along the dripping direction, so that the target material droplet is subjected to the laser action opposite to the dripping direction and is converted into plasma, and extreme ultraviolet light is generated.
10. The euv light generating device according to claim 9, comprising a drive device for moving the plasmatized target droplets away from the strike path.
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