JP4875879B2 - Initial alignment method of extreme ultraviolet light source device - Google Patents

Description

  The present invention relates to an initial alignment method in an extreme ultra violet (EUV) light source device used as a light source of an exposure apparatus.

  With the miniaturization of semiconductor processes, the miniaturization of optical lithography is rapidly progressing, and in the next generation, fine processing of 100 to 70 nm and further fine processing of 50 nm or less are required. For example, in order to meet the demand for fine processing of 50 nm or less, development of an exposure apparatus that combines an EUV light source with a wavelength of about 13 nm and a reduced projection reflection optical system (catadioptric system) is expected.

  As an EUV light source, an LPP (laser produced plasma) light source using plasma generated by irradiating a target with a laser beam, a DPP (discharge produced plasma) light source using plasma generated by discharge, There are three types: SR (synchrotron radiation) light source using orbital radiation. Among these, since the LPP light source can considerably increase the plasma density, extremely high luminance close to that of black body radiation can be obtained, and light emission only in a necessary wavelength band is possible by selecting a target material. Because it is a point light source with a typical angular distribution, there is no structure such as electrodes around the light source, and it is possible to secure a very large collection solid angle of 2πsteradian. It is considered to be a powerful light source for required EUV lithography.

  As a related technique, Patent Document 1 has first and second focal points located on one optical axis, and is arranged near the first focal point at the second confocal point or at the actual focal point. A collector mirror for focusing light from a light source configured and / or mounted so that it can be displaced in the direction of the optical axis and the second focal point does not change when the temperature changes A focusing device for radiation from a light source comprising a collector mirror is disclosed.

  Patent Document 2 discloses an apparatus for stabilizing the radiation divergence of plasma, particularly an apparatus for generating extreme ultraviolet rays, in which a luminous energy beam is directed to a target, and the target is used as the target beam. An apparatus is disclosed that is constructed and has a radiation direction substantially perpendicular to the radiation direction of the energy beam. In this device, a measurement is performed to continuously detect at least one deviation of both radiation directions with respect to the intersection of the radiation direction of the target beam and the radiation direction of the energy beam at the intersection provided as an interaction site. A measurement means having an output signal suitable as a control amount for controlling the directivity of both radiation directions with respect to the interaction site, and a radiation direction of the target beam and a radiation direction of the energy beam. An actuator is provided as a control circuit for adjusting and tracking at least one of them depending on the output signal of the measuring means.

Further, in Patent Document 3, in the extreme ultraviolet lithography technology using a laser plasma light source, in order to control the exposure amount on the wafer with high accuracy, the target is irradiated with laser light to emit light in the extreme ultraviolet region. A light source that generates light, an illumination optical system, and a projection optical system, irradiates the mask with the extreme ultraviolet light through the illumination optical system, and transfers the pattern of the mask to the sample through the projection optical system; The exposure apparatus has means for detecting the intensity of the extreme ultraviolet light, and means for controlling the exposure amount of the sample by changing the intensity of the extreme ultraviolet light generated from the target based on the detection result. An exposure apparatus is disclosed.
Japanese Patent Laid-Open No. 2002-189169 (second page, FIG. 1) Japanese Patent Laying-Open No. 2004-303725 (second page, FIG. 1) JP 2000-91195 A (pages 1 and 2)

By the way, in order to realize temporally stable EUV exposure, exposure light must be incident on the exposure machine from the light source under the same conditions. For that purpose, the following three conditions must be satisfied simultaneously.
As a first condition, the light emission point position must be spatially fixed (ideal light emission point) with respect to the exposure apparatus optical system. As a second condition, the condensing point position where EUV light is condensed by the collector mirror must be spatially fixed (ideal condensing point) with respect to the optical system of the exposure apparatus. As a third condition, the EUV radiation distribution and radiant energy at the focal point must be approximately constant.

  With respect to these points, in Patent Document 1, the collector mirror is shifted in the EUV optical axis direction in accordance with the temperature change of the collector mirror so that the focal point position is not changed. However, since only the direction of the optical axis is controlled, it is not possible to cope with various positional fluctuations of the collector mirror due to heat. In addition, it cannot cope with the position variation of the condensing point due to the position variation and shape variation of the target.

In Patent Document 2, since the position of the laser irradiation point is controlled by detecting the position of the target, the position of the light emitting point can be controlled. However, there is no mention of the condensing point fluctuation accompanying the position fluctuation of the collector mirror.
Furthermore, in Patent Document 3, EUV energy is controlled by detecting EUV energy and increasing / decreasing laser energy (second page), but there is no mention of positional fluctuations of the light emitting point and the condensing point. .

  Thus, in each of Patent Documents 1 to 3, stable exposure with EUV light cannot be realized. Moreover, the above three conditions cannot be satisfied by simply combining them. For example, by combining the techniques disclosed in Patent Documents 1 to 3, it is ideal when performing control for maintaining the position of the light emitting point and the position of the light condensing point spatially almost ideally constant. The control system must recognize the position of the target light emission point and the position of the ideal condensing point. However, the position of the ideal light emission point and the position of the ideal condensing point are related not only to the design of the EUV light source but also to the optical path design of the exposure apparatus. It is not possible to perform good exposure. Furthermore, when a control system is built so as not to deviate from the determined ideal position, the control system must always recognize the position. The recognition method is not described.

  Moreover, in said patent documents 1-3, it cannot respond to the various position fluctuations of a collector mirror. Here, the cause of the position fluctuation of the collector mirror is mainly deformation of each part caused by radiant heat of EUV plasma. The radiation heat of the EUV plasma heats not only the collector mirror but also the EUV chamber and the collector mirror holding mechanism directly or indirectly. As a result, the position and tilt of the collector mirror vary extremely widely. Specifically, although depending on the method of holding the collector mirror, for example, the tilt angle of the collector mirror and the position of the optical axis in the normal plane may change simultaneously. In such a case, as disclosed in the patent document, it is not possible to cope with the position fluctuation of the collector mirror by controlling the movement of the collector mirror in the optical axis direction or changing the shape of the collector mirror itself.

  Furthermore, when the EUV light source device is used for a long period of time, it must cope with the deterioration of the collector mirror. This is because high-energy ions, neutral particles, and fine particles are emitted from EUV plasma, so that the collector mirror gradually deteriorates due to damage caused by them, and the reflectance thereof decreases.

  In addition, this deterioration causes a nonuniform reduction in reflectance in each part of the reflecting surface in accordance with the plasma generation state. In other words, when performing control to keep the EUV energy constant, an EUV energy detection device is essential, but if only a part of the EUV light is monitored, all the EUV energy input to the exposure device can be obtained. There are cases where it is not reflected. Such a tendency becomes stronger as the collector mirror deteriorates and the variation in the reflectance distribution increases. In the above patent document, since these points are not taken into consideration, it may be difficult to put them into practical use.

  As described above, the EUV light source apparatus needs to be aligned with high accuracy before the generation of EUV light, and can operate stably against various fluctuations that occur during use of the EUV light source apparatus. In order to maintain the information, it is necessary to hold information serving as a reference for controlling each unit, for example, the position information of an ideal plasma light emission point and a condensing point.

  In view of the above problems, the present invention efficiently generates EUV light in an LPP type extreme ultraviolet light source apparatus that generates EUV light used for exposure, and efficiently uses the generated EUV light in an exposure apparatus. For the purpose.

In order to solve the above problem, an initial alignment method for an extreme ultraviolet light source apparatus according to one aspect of the present invention irradiates a target material supplied into a vacuum chamber with a laser beam for exciting the target material. This is an alignment method for an extreme ultraviolet light source device using a laser-excited plasma method that generates plasma and collects extreme ultraviolet (EUV) light generated from the plasma at a predetermined position by an EUV collector mirror. the first positional reference element disposed on the ideal emission point is should do position, placing a second position reference elements the light generated from the plasma to the ideal focal point is a position to be focused (a And adjusting the optical path of the first optical axis adjustment light so that the first optical axis adjustment light passes through the first position reference element and the second position reference element. As the second optical axis adjustment light does not pass through the second position reference element passes through the first position reference elements, to adjust the optical path of the second optical axis adjustment light, near ideal focal point A step (b) of acquiring image information of the first optical axis adjustment light using the sensor of step (b), emitting laser light from a laser light source for target excitation, and the laser light passing through the laser light condensing element to illuminate a position reference element, a laser beam the step of adjusting the position and orientation of the light focusing element and (c), the first position reference element retracts the Rutotomoni first and second optical axis adjustment light The target material is supplied to the inside of the vacuum chamber using the target injection device in a state where the first optical axis adjustment light and the second optical axis adjustment light pass through. , the step of adjusting the position and orientation of the target injection unit (d) and In a state of being retracted first and second position reference elements to stop the injection of the first and second optical axis adjustment light, step by emitting laser light from the target excitation laser light source for irradiating the target material and (e), the laser beam obtained using sensor image information of extreme ultraviolet light generated from the generated plasma by irradiating the target material, the first optical axis adjustment light image information and said based on the image information of the extreme ultraviolet light, as the polar end ultraviolet light is converged to the ideal focal point by the EUV collector mirror, and a step (f) for adjusting the position and orientation of the EUV collector mirror It has.

  According to the present invention, the plasma is generated at the ideal light emitting point, and the portions of the EUV light source device are aligned so that the light generated from the plasma is condensed at the ideal light condensing point, so that the EUV light is efficiently generated. At the same time, it can be efficiently supplied to the exposure apparatus.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
Before describing the initial alignment method according to the present invention, the configuration of the entire extreme ultraviolet (EUV) light source apparatus in which this initial alignment method is used will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration of an EUV light source apparatus. This EUV light source apparatus employs an LPP (laser excitation plasma) system and is used as a light source for an exposure apparatus.

  Here, in the present application, a spatial coordinate where plasma is actually generated is referred to as a light emission point, and a position of a light emission point determined by the alignment design of the EUV light source device is referred to as an ideal light emission point. Further, the spatial coordinates where the light generated from the plasma is actually condensed is called a condensing point, and the position of the condensing point determined by the alignment design of the EUV light source device is called an ideal condensing point.

  The EUV light source apparatus shown in FIG. 1 includes an EUV light source control apparatus 10 that controls the entire apparatus, and an EUV chamber (vacuum chamber) 11 in which EUV light is generated. The EUV chamber 11 is provided with a window 12 for introducing a laser beam (excitation laser beam) 3 for exciting a target 1 to generate plasma 2, a collector mirror 13, and an EUV filter 14. ing.

  As shown in FIG. 1, when the excitation laser beam 3 irradiates the target 1, plasma 2 is generated and light including various wavelength components is emitted together with EUV light having a wavelength component of 13.5 nm. . The collector mirror 13 reflects and collects light generated from the plasma 2 in a predetermined direction. The EUV filter 14 is a filter for selectively transmitting a predetermined wavelength component of the light collected by the collector mirror 13 and prevents an unnecessary wavelength component from entering the exposure apparatus from the EUV light source device. Is arranged. For example, when 13.5 nm EUV light is used in the exposure apparatus, a zirconium (Zr) filter is used as the EUV filter 14. The EUV light that has passed through the EUV filter 14 is introduced into the exposure apparatus via an optical transmission system. As will be described later, the EUV filter 14 is provided with a drive mechanism so that the IF position sensor 62 disposed behind can be used during initial alignment.

  1 includes a target control device 20, a target supply device 21, a target temperature / pressure (flow rate) adjustment device 22, a target injection device 23, a target position adjustment device 30, and a target position. Monitor device 31, laser control device 40, laser excitation intensity adjustment device 41, laser light source 42, laser energy monitor device 43, optical system 44, condensing element (for example, condensing lens) 45, EUV An energy monitor device 50, a laser focus adjustment device 46, a plasma monitor device 51, a collector mirror drive device 60, a collector mirror displacement monitor device 61, and an IF (intermediate focus) position sensor 62 are included. It is out. Further, the EUV light source device shown in FIG. 1 may include an EUV diode 63.

  The target supply device 21 supplies a target material such as xenon (Xe) gas to the target injection device 23. The target temperature / pressure adjusting device 22 adjusts the temperature and pressure or flow rate of the target material. Further, the target injection device 23 includes an injection nozzle having a predetermined diameter, and injects the target supplied from the target supply device 21 into the EUV chamber 11. The target control device 20 controls the operation of each of these devices under the control of the EUV light source control device 10. For example, when liquid xenon (Xe) is used as the target, the target control device 20 controls the cooling temperature and the compression pressure in the target temperature / pressure adjusting device 22 in order to liquefy the xenon gas, The supply pressure or flow rate is controlled so that liquid xenon is injected at a predetermined pressure. Thereby, for example, the liquid xenon (Xe) target 1 having a diameter of several tens of μm is supplied into the EUV chamber 11 in a jet (jet) state.

FIG. 2 shows the target position adjusting device 30 and its peripheral part.
The target position adjusting device 30 includes, for example, a vacuum-compatible automatic XY stage with a bellows, and under the control of the EUV light source control device 10, the target injection device 23 is set within a plane substantially orthogonal to the target flow. Move within the range of.

  The target position monitor device 31 is a camera including an image sensor such as a CCD (charge coupled device), for example, and outputs a signal representing the image to the EUV light source control device 10 by imaging the target 1. The target position monitoring device 31 is arranged so as to look at the target 1 from two or more different directions.

  The position of the target position monitoring device 31 is desirably aligned so that the target 1 passes through the vicinity of the center of the visual field when the position of the target 1 is adjusted so as to pass through the ideal light emission point. Further, it is desirable that the target position monitoring device 31 is arranged so that the target 1 is within the visual field range even when the target position adjusting device 30 operates to the stroke end. Further, it is desirable that the moving direction of the target position adjusting device 30 can be horizontal within the field of view. For this purpose, for example, the target position monitoring device 31 may be installed so as to look at the target 1 from the X direction of the XY stage of the target position adjusting device 30 and the Y direction orthogonal thereto. In addition, as shown in FIG. 2, the target position monitoring device 31 is arranged so as to look directly above the ideal light emitting point so that the center of the visual field deviates from the light emitting point (position where plasma is generated). The reason for this is to prevent saturation of the output of the CCD or the like due to the strong light emission from the plasma during plasma generation.

  The laser excitation intensity adjusting device 41 adjusts the excitation intensity of the laser light oscillated from the laser light source 42. The laser light source 42 generates excitation laser light 3 that is irradiated onto the target. The laser control device 40 controls the operations of these devices 41 and 42 under the control of the EUV light source control device 10. For example, in preparation for laser oscillation, the laser control device 40 warms up the excitation power source, drives the chiller, adjusts the temperature of the resonator and the optical element, and the like. Further, when a laser emission condition signal is sent from the EUV light source control device 10, the oscillation condition is set in the laser excitation intensity adjusting device 41 and the laser light source 42. Further, when receiving a laser oscillation signal from the EUV light source control device 10, the laser control device 40 causes the laser light source 42 to start laser oscillation.

  The laser energy monitor device 43 monitors the energy of the laser light emitted from the laser light source 42 and outputs a signal representing the energy value of the laser light to the laser control device 40. This signal is used by the laser control device 40 to control the laser excitation intensity adjusting device 41 so that the laser energy maintains a predetermined value.

  The optical system 44 includes a reflection mirror and an appropriate light shaping optical system, and guides the excitation laser light 3 emitted from the laser light source 42 to a condensing element (for example, a condensing lens) 45. The condensing lens 45 condenses the excitation laser light 3 and irradiates an ideal light emission point through the window 12 provided in the EUV chamber 11. The collector mirror 13 is formed with holes for allowing the excitation laser light 3 to pass therethrough.

  Under the control of the EUV light source control device 10, the laser focus adjustment device 46 adjusts the condensing lens 45 with respect to the irradiation axis direction of the excitation laser light 3 and two axes in a plane orthogonal thereto. As the laser focus adjustment device 46, for example, an XYZ stage driven by a motor can be used.

  The EUV energy monitor device 50 includes a light receiving element that detects the energy of EUV light. The EUV energy monitor device 50 is installed so as to look near the ideal light emission point, detects EUV light emitted from the light emission point, and outputs a signal representing the energy intensity to the EUV light source control device 10.

  The plasma monitor device 51 is, for example, a camera including an image pickup device such as a CCD, and is disposed in the vicinity of the ideal light emission point so that the ideal light emission point can be accommodated in the field of view. Further, in order to observe the plasma three-dimensionally, the plasma monitor device 51 preferably aligns the ideal light emission point so that the ideal light emission point faces from two or more different directions, and the ideal light emission point is arranged at the center of the visual field. Has been. For example, in order to simplify the calculation, it is desirable to make the observation axes of the two plasma monitor devices 51 orthogonal. However, the plasma monitor device 51 needs to be arranged so as not to be shaded by the optical path of the light (collected and collected) collected by the collector mirror 13.

  In addition, since plasma has high brightness, when a CCD is used as an imaging device, it is desirable to provide an appropriate optical bandpass filter in front of the light receiving surface. In that case, for example, as shown in FIG. 3, the plasma monitor device 51 can be configured. That is, an optical bandpass filter 51c provided with a drive mechanism 51b is disposed on the front surface of the CCD 51a that is an image sensor. The drive mechanism 51b is provided to change the position of the optical bandpass filter 51c, and its operation can be controlled from the outside of the EUV chamber 11.

  As will be described later, laser light is used as reference light at the time of initial alignment. However, when the reference light is observed, as shown in FIG. 3A, the optical bandpass filter 51c includes an image sensor 51a. Evacuated from the optical path of the light incident on. On the other hand, when observing plasma, as shown in FIG. 3B, the optical bandpass filter 51c is inserted in front of the image sensor 51a.

  The reason for providing such a filter is as follows. That is, in many commercially available image sensors, the dynamic range of luminance is adjusted so that weak light can be detected. Therefore, when observing the reference laser light or its scattered light, the image sensor can be used as it is. However, the difference in luminance is extremely large between the weak scattered light of the laser beam and the high-luminance plasma. Therefore, when observing the latter, it is necessary to apply an appropriate optical bandpass filter. Therefore, as shown in FIG. 3, by providing a movable filter 51c in front of the image sensor 51a, it is possible to observe both the scattered light of the reference laser beam and the plasma with one image sensor. Become.

As a modification of the plasma monitor device 51, an EUV light emission region of plasma may be observed by using an EUV light filter such as zirconium (Zr) instead of the optical bandpass filter 51c. Alternatively, the scattered light of the reference laser beam and the incident light amount of the plasma may be adjusted by providing a CCD camera with a diaphragm and an exposure time adjusting mechanism.
A signal representing an image captured by the plasma monitor device 51 is output to the EUV light source control device 10 shown in FIG.

  Referring to FIG. 1 again, the collector mirror driving device 60 is arranged such that the light generated from the plasma 2 is efficiently collected by the collector mirror 13 and guided to the light transmission system to the exposure device. And adjust posture. FIG. 4 shows the collector mirror 13 and its peripheral part. As shown in FIG. 4, the collector mirror drive device 60 includes a collector mirror drive control unit 601, an XYZ stage 602, a Θ stage 603, and a β stage 604. These stages 602 to 604 are mechanically coupled and mounted outside the EUV chamber 11, and are connected to the vacuum chamber via a bellows or the like. The reason for installing the stage in this way is to isolate it from mechanical vibration and heat conduction from the EUV chamber 11. In addition, the collector mirror 13 is normally cooled sufficiently, and thus its own thermal deformation is removed.

  The collector mirror displacement monitoring device 61 monitors fluctuations in the position and orientation of the collector mirror 13 in a non-contact manner, and outputs a detection signal representing the displacement of the collector mirror 13 to the EUV light source control device 10. As shown in FIG. 4, the collector mirror displacement monitor device 61 includes a laser displacement meter 611, an image sensor 612 such as a CCD, and a tilt detection light source 613 such as a semiconductor laser. The laser displacement meter 611 detects a change in the position of the collector mirror 13 on the XYZ axes. Further, the image sensor 612 detects the light emitted from the tilt detection light source 613 and reflected from the tilt detection reference reflection surface 614 provided on the back surface of the collector mirror 13, whereby the Θ angle of the collector mirror 13 is detected. And the displacement of β angle is detected.

  The IF position sensor 62 is a camera including an image sensor such as a CCD, for example, and is provided in the vicinity of the ideal condensing point in order to capture an image in the vicinity of the condensing point. Here, since the ideal condensing point of EUV light is normally designed to be formed on the EUV filter 14, the IF position sensor 62 is arranged behind the EUV filter 14 (on the exposure apparatus side). The image information acquired by the IF position sensor 62 is output to the EUV light source control device 10. The IF position sensor 62 is provided with a drive mechanism that can be controlled from the outside of the EUV chamber 11. As shown in FIG. 4, the IF position sensor 62 can observe an ideal condensing point (optical path of EUV light) while observing the condensing point during initial alignment or EUV energy calibration. While being exposed in the exposure apparatus, it is retracted out of the optical path of the EUV light.

FIG. 5 shows the positional relationship between the IF position sensor 62 and the EUV filter 14 disposed in front of the IF position sensor 62. As shown in FIG. 5, the EUV filter 14 is provided with a drive mechanism that can be controlled from the outside of the EUV chamber 11. As shown in FIG. 5A, when the reference laser beam is incident on the IF position sensor 62 during the initial alignment, the EUV filter 14 is retracted out of the optical path. On the other hand, as shown in FIG. 5B, when the EUV light condensing point is observed by the IF position sensor 62, the EUV filter 14 is inserted into the optical path.
As will be described later, the EUV diode 63 is moved and used in the vicinity of the ideal focal point when the EUV energy monitor device 50 is calibrated.

  Next, an initial alignment method for the EUV light source apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 6 to 8. In this initial alignment, each part is adjusted so that the target and the excitation laser intersect at the ideal light emission point, and the light generated from the plasma is condensed at the ideal light collection point.

  FIG. 6 shows an extracted portion of the EUV light source apparatus shown in FIG. 1 that is used in the initial alignment. Further, as shown in FIG. 6, in the initial alignment, in addition to the EUV light source device shown in FIG. 1, reference laser light sources 70 and 72 and optical systems 71 and 73 are arranged.

  The reference laser light sources 70 and 72 generate reference laser light (optical axis adjustment light) used during initial alignment. As the reference laser light sources 70 and 72, a light source having a wavelength and intensity in a range that does not cause damage even when each component of the EUV light source device is irradiated and having good visibility is used. Specifically, a He—Ne laser, a visible region semiconductor laser, or the like is appropriate.

  The optical system 71 including a reflection mirror and the like is arranged so that the first reference laser light 4 generated from the reference laser light source 70 penetrates the ideal light emission point and the ideal condensing point, preferably the exposure light path of the exposure apparatus. Form an optical path. On the other hand, the optical system 73 including a reflection mirror or the like forms an optical path so that the second reference laser light 5 generated from the reference laser light source 72 passes through the ideal emission point. The intersection of these reference laser beam 4 and reference laser beam 5 is an ideal emission point.

  FIG. 7 shows the state of the EUV chamber 11 and its surroundings as viewed from the top of the chamber during the initial alignment. As shown in FIG. 7, the plasma monitor device 51 is arranged so as not to block the optical paths of the reference laser beams 4 and 5. Further, it is desirable that the plasma monitor device 51 is arranged so as to look at the observation target (plasma) from an angle of 90 degrees with each other.

FIG. 8 is a flowchart showing an initial alignment method of the EUV light source apparatus according to the first embodiment of the present invention.
In step S11 of FIG. 8, the optical paths of the first reference laser beam 4 and the second reference laser beam 5 are adjusted. For this purpose, first, a position reference element such as a pin is arranged at an ideal light emitting point and an ideal condensing point. These position reference elements are preferably installed on a plane where mechanical accuracy is guaranteed. Then, the reference laser light source 70 is emitted from the reference laser light source 70, and the reference laser light source 70 or the reference laser light source 70 passes through the position reference elements respectively disposed at the ideal light emission point and the ideal condensing point. The position and posture of the optical system 71 are adjusted. Then, the laser beam 5 for reference emitted from the reference laser light source 72, the reference laser beam 5 passes through the position reference elements arranged on the ideal emission point, pass through the position reference elements arranged on an ideal focal point The position and orientation of the reference laser light source 72 or the optical system 73 are adjusted so that there is no such problem. In that case, it is preferable that the optical path of the reference laser beam 5 crosses the optical path of the reference laser beam 4 at a right angle because it becomes easy to understand intuitively in later adjustment.

  The reference laser beam 4 whose optical path is adjusted in step S11 is detected by the IF position sensor 62 moved to the vicinity of the condensing point. The image information (irradiation pattern) of the reference laser beam 4 acquired thereby is output to the EUV light source control device 10 and stored therein. As shown in FIG. 5A, at this time, the EUV filter 14 is retracted out of the optical path of the reference laser beam 4.

  Next, in step S12, the optical path of the excitation laser beam 3 is adjusted. For this purpose, the laser light source 42 shown in FIG. 1 is driven to perform laser oscillation, and the position and orientation of the condenser lens 45 are adjusted so that the excitation laser light 3 passes through the position reference element disposed at the ideal light emission point. adjust. In this step, the intensity of the excitation laser beam 3 does not need to be as high as that during exposure. After adjusting the optical paths of the reference laser beams 4 and 5 and the excitation laser beam 3, the position reference elements arranged at the ideal emission point and the ideal condensing point are retracted from the optical path.

  Next, in step S <b> 13, the target 1 is ejected from the target ejection device 23, and the position and orientation of the target ejection device 23 are adjusted, thereby performing alignment so that the target 1 passes through the ideal light emission point. As the target 1 crosses the optical path of the reference laser beam 4 or 5, scattered light is generated. Therefore, while observing the scattered light with the plasma monitor device 51, the target emission device 23 is moved by the target position adjusting device 30 to search for a position where the intensity of the scattered light is the strongest. For example, by moving the target injection device 23 in the ± X direction, the target 1 is placed on the optical path of the reference laser light 5, and then the target injection device 23 is moved in the ± Y direction, thereby Are arranged at the intersection of the reference laser beam 4 and the reference laser beam 5. Thereby, the target 1 is aligned with the ideal light emission point. The EUV light source control device 10 stores the image of the scattered light (scattered light position information) at that time as the position information of the ideal light emission point.

  Such position adjustment of the target injection device 23 may be performed manually with reference to the scattered light image acquired by the plasma monitor device 51 or automatically by the EUV light source control device 10. good. Further, after the alignment of the target 1 is completed, the emission of the reference laser beams 4 and 5 is stopped.

  Next, in step S <b> 14, the excitation laser beam 3 is emitted by driving the laser light source 42 shown in FIG. 1, and the target 1 is irradiated through the condenser lens 45. Thereby, the target 1 is excited and the plasma 2 is generated. In this case, the intensity of the excitation laser beam 3 does not have to be as high as that at the time of exposure, and is as low as possible (low energy and low repetition frequency) in order to suppress deformation of the collector mirror 13 and the like. It is desirable to do in.

  The light generated from the plasma 2 is collected by the collector mirror 13 and guided to the condensing point. An image at the condensing point (condensed image) is observed by the IF position sensor 62. The condensed image acquired thereby is output to the EUV light source controller 10 and stored therein.

Next, in step S15, based on the condensed image acquired by the IF position sensor 62, the position and posture of the collector mirror 13 are adjusted so that the light generated from the plasma 2 is collected at the ideal focal point. . Thereby, the position and attitude of the collector mirror 13 are adjusted so that the optical axis of the light collected by the collector mirror 13 passes through the ideal light emission point and the ideal light collection point. Further, the position and posture of the collector mirror 13 may be adjusted so that the light collected by the collector mirror 13 is collected at the ideal spot with a minimum spot diameter.
Hereinafter, specific processing in step S15 will be described.
The EUV light source control device 10 calculates the center or area center of gravity of the condensed image acquired in step S14, and calculates and stores the difference from the image center of the first reference laser light 4 acquired in step S11. To do. Further, the EUV light source control device 10 calculates and stores the area value and the roundness of the condensed image. Then, the EUV light source control device 10 adjusts the position and posture of the collector mirror 13 by controlling the collector mirror driving device 60 (see FIGS. 1 and 4) based on those calculated values. That is, the angle of the collector mirror 13 is adjusted by scanning the Θ stage 603 and the β stage 604 so that the roundness of the condensed image is maximized. Further, the X stage and the Y stage are scanned so that the center of the condensed image coincides with the image center of the reference laser beam 4. Further, the Z stage is scanned so that the area value of the condensed image becomes a specified value.

  Next, in step S <b> 16, the collector mirror displacement monitor device 61 (see FIG. 4) measures the position of the condenser mirror 13 with the three laser displacement meters 611 and outputs the measured value to the EUV light source device 10. The EUV light source control device 10 stores these displacement values as “calibrated collector mirror positions”.

  By performing the initial alignment described above, in the EUV light source device, plasma can be formed in the vicinity of the ideal light emitting point, and the light generated from the plasma can be condensed on the ideal condensing point by the collector mirror 13. It becomes possible. Further, by storing the “calibrated collector mirror position”, it is possible to adjust each part during the operation (exposure) of the EUV light source device.

  In the initial alignment method of the EUV light source apparatus according to the present embodiment described above, the order of the optical path adjustment of the reference laser light in step S11 and the optical path adjustment of the excitation laser light in step S12 may be switched. That is, after the position reference elements are arranged at the ideal emission point and the ideal condensing point, the optical path of the excitation laser beam may be adjusted first, and then the optical path of the reference laser beam may be adjusted.

  Next, an initial alignment method of the EUV light source apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In this embodiment, as an alignment reference, in addition to the position of the ideal light emission point and the position of the ideal condensing point, an optical path of an optical transmission system that guides EUV light to the exposure apparatus (hereinafter referred to as an exposure optical path) is used. It is characterized by.

First, in step S11 of FIG. 8, the optical paths of the first reference laser beam 4 and the second reference laser beam 5 are adjusted. For this purpose, a position reference element such as a pin is arranged at the ideal light emission point and the ideal light condensing point, and a third position reference element such as a pin is also arranged in the exposure optical path. As shown in FIG. 6, the position of the third position reference element is on a straight line connecting the ideal light emission point and the ideal light collection point, and is opposite to the ideal light emission point when viewed from the ideal light collection point. Then, the reference laser light source 70 or the optical system so that the reference laser light 4 passes through the position reference element arranged at the ideal light emission point or the ideal condensing point while passing through the position reference element arranged in the exposure optical path. The position and posture of 71 are adjusted. Next, the reference laser light source 72 or the optical system 73 is controlled so that the reference laser beam 5 passes through the position reference element disposed at the ideal light emission point and does not pass through the position reference element disposed at the ideal condensing point. Adjust position and posture.
The processes after step S12 are the same as those in the first embodiment.
According to the present embodiment, since the exposure optical path is used as the alignment reference, the EUV light generated in the EUV light source apparatus can be reliably and efficiently guided to the exposure apparatus side.
Also in this embodiment, the order of the optical path adjustment of the reference laser beams 4 and 5 and the optical path adjustment of the excitation laser beam 3 may be switched.

Next, an alignment method for an EUV light source apparatus according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart showing an initial alignment method of the EUV light source apparatus according to this embodiment.
In step S21 of FIG. 9, the optical paths of the first reference laser beam 4 and the second reference laser beam 5 are adjusted. This optical path adjustment method is the same as that described in the first or second embodiment (step S1 in FIG. 8). Further, image information (irradiation pattern) of the reference laser beam 4 whose optical path is adjusted is acquired by the IF position sensor 62 and stored in the EUV light source control device 10. After this optical path adjustment is completed, the position reference elements arranged at the ideal light emission point and the ideal light condensing point are retracted from the optical path.

  Next, in step S <b> 22, the target 1 is ejected from the target ejection device 23, and the position and orientation of the target ejection device 23 are adjusted, thereby performing alignment so that the target 1 passes through the ideal light emission point. The alignment method is the same as that in the first embodiment (step S13 in FIG. 8).

  Next, in step S23, the optical path of the excitation laser beam 3 is adjusted. For this purpose, the excitation laser beam 3 is emitted from the laser light source 42 and the target 1 is irradiated with the excitation laser beam 3 through the condenser lens 45. Thereby, the target 1 is excited and plasma 2 is generated. In this case, the intensity of the excitation laser beam 3 does not have to be as high as that at the time of exposure, and is as low as possible (low energy and low repetition frequency) in order to suppress deformation of the collector mirror 13 and the like. It is desirable to do in.

  The plasma 2 generated in this way is imaged by the plasma monitor device 51. Therefore, while observing the position of the plasma image acquired by the plasma monitor device 51, the position and posture of the condenser lens 45 are adjusted so that the excitation laser beam 3 irradiates the ideal light emission point. This adjustment may be performed manually or automatically by the EUV light source control device 10. In the case of automatic adjustment, for example, the spot center of the irradiation pattern of the reference laser light 4 acquired in step S21 is made to coincide with the center of the plasma image. If the required value for the position accuracy of the condensing point is low, the condensing lens 45 may be adjusted while visually observing the position of the plasma.

  In addition, light (EUV light) generated from the plasma 2 is collected by the collector mirror 13 and guided to the condensing point. An image at the condensing point (condensed image) is observed by the IF position sensor 62. The condensed image acquired thereby is output to the EUV light source controller 10 and stored therein.

Next, in step S24, the position and orientation of the collector mirror 13 are adjusted based on the condensed image acquired by the IF position sensor 62 so that the light generated from the plasma 2 is collected at the ideal focal point. . The processing in step S24 is the same as that in the first embodiment (step S15 in FIG. 8).
Further, in step S25, the displacement value of the collector mirror 13 whose position and orientation are adjusted is stored as a “calibrated collector mirror position”.
In the present embodiment, the optical path of the excitation laser beam 3 (that is, the condensing lens 45) is adjusted while observing plasma with high brightness, so that the operation becomes easier.

  Next, an initial alignment method for the EUV light source apparatus according to the fourth embodiment of the present invention will be described with reference to FIGS. In this initial alignment method, the EUV light source controller 10 can recognize the position of the ideal light emitting point, the position of the ideal condensing point, and the position and orientation of the collector mirror without forming a target flow. In the present embodiment, only one reference laser beam is used.

FIG. 10 is a flowchart showing an initial alignment method according to the present embodiment. FIG. 11 is a schematic diagram for explaining the initial alignment method according to the present embodiment.
First, in step S31, the optical path of the reference laser beam 4 is adjusted so as to pass through the ideal light emission point, the ideal condensing point, and the exposure optical path. This optical path adjustment is the same as in the second embodiment (step S21 in FIG. 9). Further, image information (irradiation image) of the reference laser beam 4 whose optical path is adjusted is acquired by the IF position sensor 62 and stored in the EUV light source device 10.

  Next, in step S32, the EUV light source control device 10 calculates the spot center of the irradiation pattern of the reference laser light 4, and stores that point as an ideal condensing point. Here, since the optical path of the reference laser beam 4 passes through the ideal emission point, the ideal condensing point, and the exposure optical path, the spot center in the irradiation pattern of the reference laser beam 4 is the ideal condensing point. Become.

  Next, in step S33, a reflection pin (or a scatterer that scatters laser light) 74 is set up at the ideal emission point. The diameter of the reflection pin 74 is preferably about the same as or smaller than that of the plasma 2 (see FIG. 1). By raising the reflection pin 74, the reference laser beam 4 is scattered and emitted to the surroundings, and the scattered light is collected near the ideal focal point by the collector mirror 13. The scattered light at the ideal light emission point is detected by the plasma monitor device 51, and the condensed light at the condensing point is detected by the IF position sensor 62.

In step S34, the image information of the scattered light of the reference laser beam 4 acquired by the plasma monitor device 51 is stored in the EUV light source control device 10 as the position information of the ideal emission point.
In step S <b> 35, the position and orientation of the collector mirror 13 are adjusted based on the image of the condensed light by the collector mirror 13 acquired by the IF position sensor 62. For this purpose, the EUV light source controller 10 determines that the center of the image of the condensed light output from the IF position sensor 62 is the position of the ideal condensing point (spot center of the reference laser light 4) acquired in step S32. The collector mirror driving device 60 is operated so as to overlap. In this case, since the wavelengths of the EUV light and the reference laser light 4 are different, the EUV light source control device 10 acquires aberrations due to the wavelengths in advance, and determines the focal position of the collector mirror 13 including the aberrations. adjust.

  As described above, according to the present embodiment, the EUV light source controller 10 recognizes the position of the ideal light emitting point and the position of the ideal condensing point without forming a target flow or generating plasma. The position and posture of the collector mirror 13 can be easily adjusted.

  Next, in the EUV light source apparatus shown in FIG. 1, a control operation for stabilizing the position of the light emitting point, the position of the condensing point, and EUV energy will be described with reference to FIGS. 1 and 12. FIG. 12 is a block diagram showing a control system in the EUV light source apparatus shown in FIG. These operations are performed while generating EUV light for exposure.

(1) Target alignment By injecting liquid xenon by the target injection device 23, a liquid or solid cylindrical target flow (target 1) having a diameter of several tens of μm is formed in the EUV chamber 11. When the target is aligned, the position of the target 1 is imaged by the target position monitor device 31.

  The target position monitor device 31 images the target 1 from two directions almost simultaneously at regular time intervals, and outputs image information of the target 1 to the EUV light source control device 10. Here, the target 1 is initially aligned so as to pass through the ideal light emission point, and the EUV light source control device 10 acquires information on the center position of the target when passing through the ideal light emission point.

  Therefore, the EUV light source control device 10 calculates the current position of the target 1 based on the actual target observation image obtained by the target position monitor device 31. Then, by comparing with the center position information of the target when passing through the ideal light emitting point, the difference between them is calculated. The EUV light source control device 10 converts the difference value into an axial movement amount in the target position adjustment device 30 and outputs it, thereby causing the target position adjustment device 30 to shift the position of the target injection device 23 by a predetermined amount. Thereby, it adjusts so that the target 1 may pass an ideal light emission point. Such an adjustment operation may be always performed while the target is being injected, or may be performed at regular time intervals. Desirably, the adjustment is repeated in the shortest possible cycle. Thereby, the state in which the target 1 passes through the ideal light emitting point can be maintained.

  In such a target alignment operation, instead of the target center position information at the ideal light emission point obtained at the initial alignment, a thin line having a thickness corresponding to the target diameter is attached to the ideal light emission point in the chamber, Data obtained by imaging this with the target position monitor device 31 may be used. Alternatively, a coordinate value determined by mechanical alignment from the apparatus configuration may be numerically input as target position information at the ideal light emission point.

(2) EUV energy control In the EUV energy control operation, in order to generate stable EUV energy, control is performed so that the excitation laser beam oscillates under a predetermined condition.
When the EUV light source control device 10 transmits a signal indicating a laser oscillation condition to the laser control device 40, the laser control device 40 performs a predetermined setting for the laser excitation intensity adjustment device 41 based on the oscillation condition. . Next, the laser control device 40 causes the laser light source 42 to start laser oscillation by receiving a laser oscillation signal from the EUV light source control device 10.

  The laser energy monitor device 43 monitors the energy of the laser light emitted from the laser light source 42 and outputs a signal representing the monitor value to the laser control device 40. The laser control device 40 compares this monitor value with the target laser energy value, and if they are different, the command signal is sent to the laser excitation intensity adjusting device 41 so as to correct the laser excitation intensity. Is output. For example, when the laser light source is a discharge excitation type gas laser, the command signal represents a command value of the excitation voltage. As described above, the output energy from the laser light source 42 can be sequentially adjusted to an appropriate value based on the command signal output from the EUV light source control device 10.

  Further, the EUV light source control device 10 receives an EUV energy command value, a repeat command value, and an EUV generation interval condition such as a burst mode from the exposure device, converts them into laser operating conditions, and outputs them to the laser control device 40. To do. The EUV light source control device 10 refers to the EUV energy command value and the EUV energy at the focal point calculated from the monitor value of the EUV energy while generating the EUV light, and the difference between the two. The output value of the laser energy is adjusted so that becomes smaller. Thus, by adjusting the laser energy based on the command value output from the exposure apparatus, EUV energy having an appropriate output value can be output at an appropriate generation interval.

(3) Laser irradiation point control (light emission point control)
In order to obtain stable EUV energy, it is necessary to stabilize the position of the light emitting point. For this purpose, by adjusting the irradiation point (focal position) of the excitation laser beam 3 by the condenser lens 45, the state in which plasma is generated at the ideal light emission point is maintained. The condenser lens 45 is adjusted by the laser focus adjusting device 46 while observing an image of plasma at the light emitting point or referring to the value of EUV energy being detected.

  The EUV energy monitor device 50 is used for observing the EUV energy. The value of the EUV energy detected by the EUV energy monitor device 50 is the initial stage when the EUV light source device is operated, that is, the collector mirror 13 is not contaminated or damaged. It is desirable that correspondence with the EUV energy value of the condensing point in the state is taken. The EUV energy value at this focal point becomes the initial calibration value. This initial calibration value is corrected at any time by calibration of the EUV energy monitor device, as will be described in detail later.

  As shown in FIG. 1, the target flow (target 1) is adjusted in advance so as to pass through the ideal emission point by the initial alignment described above. By irradiating the target 1 with the excitation laser beam 3, plasma is generated in the vicinity of the ideal emission point. At that time, when plasma is not generated because the excitation laser beam 3 is deviated from the target 1, the focusing lens 31 is moved in a plane perpendicular to the laser irradiation axis by the laser focus adjustment device 46. Plasma is emitted. This plasma is imaged by the plasma monitor device 51, and image information of the plasma is output to the EUV light source control device 10.

  The EUV light source control device 10 calculates the current light emission point based on the plasma observation image output from the plasma monitor device 51 and compares it with the position information of the ideal light emission point, thereby calculating the difference between them. Then, the difference value is converted into an axial movement amount of the laser focus adjusting device 46 and output to the laser focus adjusting device 46. The laser focus adjustment device 46 shifts the condenser lens 45 by the amount of this axial movement. Thereby, the position of the condensing lens 45 in the plane orthogonal to the laser irradiation axis is adjusted, and the light emitting point is positioned at the ideal light emitting point.

  Or you may adjust the focus of a condensing lens based on the plasma surface area information calculated | required from a plasma observation image. That is, the EUV light source control device 10 acquires a plasma observation image from the plasma monitor device 51 and calculates a plasma surface area. Then, the calculated plasma surface area is compared with the plasma surface area at the ideal emission point acquired in advance, and based on the difference, the laser focus adjustment device 46 is controlled and collected so that the difference in plasma surface area is minimized. The optical lens 45 is moved in the laser irradiation axis direction. In this case, it is desirable that the EUV light source control device 10 obtains the plasma surface area information obtained from the observation image of the plasma generated at the ideal emission point in advance by experiment. May be obtained in advance.

  Furthermore, the focus of the condenser lens may be adjusted based on the EUV energy value acquired by the EUV energy monitor device 50. That is, the EUV light source control device 10 adjusts the laser focal point so that the EUV energy at the focal point becomes maximum when the detected EUV energy value is lower than the specified value of the EUV energy corresponding to the laser energy at that time. The adjusting device 46 is controlled to move the condenser lens 45 in the laser irradiation axis direction.

In the laser irradiation point control method described above, any one of the method using the surface area of the plasma observation image and the method referring to EUV energy may be selected and used, but both may be used in combination. Absent.
Such adjustment may be always performed while the excitation laser beam 3 is irradiated, or may be performed at regular time intervals. Desirably, the adjustment should be repeated in as short a cycle as possible. As a result, plasma can always be generated at the ideal emission point.

  Here, in a general EUV light source device, in order to determine the position of the condenser lens 45, a target flow (target 1) must be formed. However, in the EUV light source device shown in FIG. 1, it is also possible to determine the position of the condenser lens 45 without forming a target flow. Two methods will be described below.

As a first method, first, the EUV chamber 11 is filled with nitrogen (N ₂ ) or air. By irradiating the excitation laser beam 3 in such a state, air plasma is generated. Since this air plasma is formed in the vicinity of the focal point of the excitation laser beam 3, the position and posture of the condenser lens 45 are controlled by controlling the laser focus adjusting device 46 so that the air plasma is arranged at the ideal light emission point. Adjust. Here, the size of the air plasma changes depending on the focal length of the condenser lens 45, the wavelength of the excitation laser beam 3, the laser energy, the laser pulse width, and the like, so that the size of the air plasma becomes the same size as the EUV plasma. In addition, it is determined by conducting an experiment in advance. The plasma size can be changed by adjusting the pressure in the EUV chamber 11 if the parameters of the condenser lens 45 and the excitation laser beam 3 are determined.

  As a second method, plasma is generated by arranging a fine line or the like at an ideal light emission point and irradiating the line with the excitation laser beam 3. The position of the condenser lens 45 is adjusted by controlling the laser focus adjustment device 46 while referring to this plasma. The material of the line arranged at the ideal light emitting point may be metal or non-metal, but it is necessary to select the material so that it does not become a contaminant. Further, when the line is worn by forming plasma, a mechanism that can continuously supply the line while adjusting the condenser lens 45 may be provided. As a result, the adjustment work time can be shortened.

(4) Calibration of EUV energy monitor device When the EUV light source device shown in FIG. 1 is used for a long period of time, the collector mirror 13 and the EUV filter 14 are damaged or deteriorated. For example, the collector mirror 13 and the EUV filter 14 are scraped by neutral particles and ions generated from plasma, and the position of the condensing point of the EUV light is shifted, or the transmittance of the EUV filter 14 is partially increased. . On the other hand, when the target material (debris) that has not contributed to plasma generation adheres to the collector mirror 13 or the EUV filter 14, the reflectivity of the mirror and the transmittance of the filter are reduced. As a result, there may be a difference between the EUV energy observed by the EUV energy monitor device 50 and the EUV energy actually output to the exposure apparatus. In order to prevent such a phenomenon, it is necessary to periodically calibrate the EUV energy monitor device 50.

  First, before the EUV energy monitor device 50 is calibrated, EUV light is generated, and the monitor value of the EUV energy monitor device 50 (light energy E1 at the light emission point) and the EUV light collected by the collector mirror 13 are compared. The relationship between the energy and the value measured by the EUV diode 63 (light energy E2 at the condensing point) arranged at the ideal condensing point is acquired in advance. The relationship between E1 and E2 is expressed by a function such as E2 = f (E1), and is stored in the EUV light source controller 10.

When the EUV energy monitor device 50 is calibrated, the EUV light 63 collected by the collector mirror 13 is moved by moving the EUV diode 63 to the rear of the ideal condensing point when the exposure device is not performing exposure. Measure. The measured value E2 is output to the EUV light source control device 10.
At the same time, the EUV energy monitor device 50 acquires the EUV energy monitor value E1. The EUV light source control device 10 calibrates the output from the EUV energy monitor device 50 by comparing the monitor value E1 with the previously measured EUV energy measurement value E2. Specifically, the values of E1 and E2 acquired this time are substituted into a function stored in advance in the EUV light source control apparatus 10, and the function is corrected as needed so that the function is established. Such an operation is performed at regular intervals.

  By performing such calibration, when there is a change in the reflectance of the collector mirror 13 or the transmittance of the EUV filter 14, the EUV light source control device 10 can easily detect the change. For example, when the reflectance is lowered, the output energy of the EUV light can be kept constant by outputting a command signal to the laser control device 40 and increasing the laser output.

Further, when it is determined by this calibration operation that the reflectance is not more than a predetermined value, the EUV light source control device 10 may notify the user that it is time to replace the collector mirror. .
In this calibration operation, not all of the EUV light used for exposure is measured, but all of the EUV light supplied to the exposure apparatus is measured. Therefore, even when the collector mirror 13 is unevenly worn, EUV energy can be accurately detected.

  Examples of a method for detecting the uneven wear state of the collector mirror 13 include the method described below. When the exposure apparatus is not performing exposure, the IF position sensor 62 is disposed in the vicinity of the ideal focal point. Then, the EUV light is imaged by the IF position sensor 62, and the image information is output to the EUV light source control device 10. The EUV light source control device 10 detects the partial wear state of the collector mirror based on the intensity distribution of the EUV light image.

At that time, if a remarkable bright spot is observed in the EUV light image, the EUV filter 14 may be damaged. In such a case, the EUV light source control device 10 may notify the user that the EUV filter 14 needs to be replaced.
It is desirable to perform such inspection regularly.

  Further, the EUV light source control device 10 integrates the total luminance of the image obtained by the IF position sensor 62 and acquires the correspondence between the integrated value and the measured value obtained by the EUV diode 63 in advance. good. Thereby, the EUV energy can be calibrated by using the IF position sensor 62 instead of the EUV diode 63. Further, by acquiring this correspondence at the time of manufacturing the EUV light source device, the EUV diode 63 can be omitted in the operating environment of the EUV light source device after shipment.

(5) Control of collector mirror (control of condensing point)
By the initial alignment described above, the position information of the ideal focal point and the information of “calibrated collector mirror position” are stored in the EUV light source control device 10. Therefore, as shown in FIG. 4, the EUV light source control device 10 obtains information representing the displacement of the collector mirror 13 from the collector mirror displacement monitor device 61 during exposure, and the information is “calibrated collector mirror position”. By comparing with the information, the difference between the two is calculated. Then, the EUV light source control device 10 uses the collector mirror driving device 60 (collector mirror control unit 601, XYZ stage 602, Θ) so that the collector mirror 13 maintains the calibrated collector mirror position based on the difference value. The stage 603 and the β stage 604) are operated.

  By repeatedly performing such a control operation during exposure, the position and posture of the collector mirror 13 are maintained in an appropriate state. Thereby, the condensing point of the light generated from the plasma 2 is maintained at a certain position that is very close to the ideal condensing point. The calibration of the collector mirror performed using the IF position sensor 62 (see FIG. 8) may be performed only when the EUV light source device is started up, or may be performed intermittently while exposure is not being performed. good.

The initial alignment method of the EUV light source apparatus according to the first to fourth embodiments of the present invention can also be applied to an EUV light source apparatus having a configuration different from that of the EUV light source apparatus shown in FIG. Below, the structural example of such an EUV light source device is demonstrated.
FIG. 13 shows a modification of the control system of the EUV light source device shown in FIGS. In FIG. 12, each part is centrally controlled by the EUV light source controller 10, whereas in FIG. 13, control for failure diagnosis (monitoring of target position, focus position, and collector mirror position). Except for, distributed processing is performed.

  As shown in FIG. 13, target position control, laser focus position control, and collector mirror displacement control are independently performed by the target position adjusting device 30, the laser focus adjusting device 46, and the collector mirror driving device 60. Has been done. By distributing the processing in this manner, for example, even when the load of image processing is high, the load of numerical processing in the EUV light source control device 10 can be significantly reduced. Therefore, a control device can be configured by combining inexpensive consumer products.

FIG. 14 is a schematic diagram showing a configuration of an EUV light source device that forms droplets (droplets) and targets instead of the target flow.
The EUV light source device shown in FIG. 14 includes a target control device 80 instead of the target control device 20 shown in FIG. 1, and further includes a target injection timing adjustment device 81. Further, this EUV light source device has a target position / velocity monitoring device 82 instead of the target position monitoring device 31 shown in FIG. Further, this EUV light source device is configured by replacing a laser control device 40, a laser excitation intensity adjusting device 41, a laser energy monitoring device 43, and a plasma monitoring device 51 shown in FIG. An adjustment device 84, a laser energy / timing monitoring device 85, and a plasma position / timing monitoring device 86 are provided.

  Here, when forming droplets, it is common to use a drop-on-demand method or a continuous jet method. In either method, the droplet injection timing is a control signal that gives the heating timing of the micro heater (in the case of the drop-on-demand method) or the driving timing of the piezo element (in the case of the continuous jet method). Can be controlled by supplying from the outside. In the present application, as an example, a case where xenon (Xe) droplets are formed by a continuous jet method will be described.

  In the continuous jet method, it is known that there is a droplet stable generation condition of λ / D to 8 between the disturbance period λ given by the piezo element and the droplet diameter D. When a droplet of several tens of μm is to be realized, the disturbance period λ is likely to be in the order of megahertz. On the other hand, the repetition frequency of the laser used in the currently proposed LPP-type EUV light source device is about 100 kHz at the highest, which is about an order of magnitude less than the period necessary for generating droplets. Therefore, according to the continuous jet method, one of several droplets is irradiated with excitation laser light.

  As shown in FIG. 14, the EUV light source control device 10 drives the target control device 80 by receiving an EUV light emission command. This EUV emission command includes EUV energy and EUV emission timing. Then, the EUV light source control device 10 generates a reference timing signal that is the same as the EUV light emission timing, and supplies the reference timing signal to the target injection timing adjustment device 81.

  The target control device 80 controls the cooling temperature and the compression pressure in the target temperature / pressure adjusting device 22 in order to liquefy the xenon gas supplied by the target supply device 21, and the liquid xenon is supplied with a predetermined pressure ( The supply pressure or flow rate in the target injection device is controlled so that the injection is performed at a flow rate.

  The target injection timing adjustment device 81 includes, for example, a piezo element, and drives the piezo element at a predetermined vibration frequency based on the reference timing signal supplied from the EUV light source control device 10, thereby enabling the target injection device. 23 is vibrated. Specifically, the vibration frequency of the piezo element is an integral multiple of the reference timing signal. Thereby, the target injected from the target injection device 23 is made into droplets.

  The target position / velocity monitor device 82 images the ejected droplet target 7 and outputs a signal representing the image to the EUV light source control device 10. FIG. 15 is a schematic diagram illustrating a configuration example of the target position / speed monitor device 82. As shown in FIG. 15A, the target position / speed monitor device 82 includes, for example, a plurality of high-speed CCD cameras 801 and 802. The high-speed CCD cameras 801 and 802 are arranged above the light emitting point so that the target can be observed from two or more different directions.

  The high-speed CCD cameras 801 and 802 are desirably aligned so that the droplet target 7 passes through the ideal light emission point when the droplet target 7 passes through the vicinity of the center of the visual field. Further, the visual field range of these high-speed CCD cameras 801 and 802 is preferably such that the droplet target 7 is within the visual field even when the target position adjusting device 30 operates to the stroke end. Further, it is desirable that the moving direction of the target position adjusting device 30 can be expected to be horizontal within the field of view. For this purpose, for example, the target position / velocity monitoring device 82 may be installed so as to look at the droplet target 7 from the X direction of the XY stage of the target position adjusting device 30 and the Y direction orthogonal thereto.

  The laser energy / timing monitor device 85 monitors the energy of the laser light emitted from the laser light source 42 and the irradiation timing, and outputs a signal representing the energy value of the laser light to the laser control device 83 at a predetermined timing. This signal is used by the laser control device 83 to control the laser excitation intensity / timing adjustment device 84 so that the laser energy and the irradiation timing maintain predetermined values.

  The plasma position / timing monitor device 86 observes the plasma 2 generated by irradiating the droplet target 7 with the excitation laser beam 3 from two different directions (for example, the X direction and the Y direction). The image information of the plasma 2 acquired by the plasma position / timing monitor device 86 is output to the EUV light source control device 10.

Next, the target alignment operation in the EUV light source apparatus shown in FIG. 14 will be described.
First, prior to alignment, the EUV light source control device 10 has information on the speed (interval) and position (coordinates in the X and Y directions) of the droplet target in a state where the target is aligned with the ideal light emission point ( The position information of the target passing through the ideal light emission point) is acquired in advance. For example, after the initial alignment, the droplet target is ejected, and as shown in FIG. 15A, the target position / velocity monitoring device 82 preferably simultaneously synchronizes with the target ejection timing from two directions at almost the same time. A target image is captured. Then, the EUV light source control device 10 performs image processing on these images (see FIG. 15B), thereby acquiring the position information of the target that passes through the ideal emission point. Alternatively, for simple observation, a small sphere or the like having a size corresponding to the diameter of the droplet / target is installed at the ideal light emitting point in the EUV chamber 11, and this is detected by the target position / velocity monitoring device 82. Based on the captured image, the position information of the target passing through the ideal light emission point may be calculated.

  When performing target alignment, the target position / velocity monitoring device 82 captures the current droplet target 7 from two directions at almost the same time, preferably in synchronization with the target injection timing, and the observation image is obtained. Output to the EUV light source controller 10. The EUV light source control device 10 calculates the current position of the droplet target 7 based on the observation image of the current droplet target 7. And the difference between them is calculated by comparing the position information with the position information of the target passing through the light emitting point. The EUV light source control device 10 converts the difference value into an axial movement amount in the target position adjusting device 30 and outputs it, thereby controlling the target position adjusting device 30 and setting the position of the target position emitting device 23 to a predetermined value. Shift by the amount. Thereby, the droplet target 7 is adjusted so as to pass through the ideal light emitting point. Such an adjustment operation may be always performed while the droplet target 7 is being injected, or may be performed at regular time intervals. Preferably, it is repeated as short as possible. Thereby, the state in which the droplet target 7 passes through the ideal emission point can be maintained.

Next, the laser irradiation timing control operation in the EUV light source apparatus shown in FIG. 14 will be described.
The EUV light source control device 10 calculates the laser irradiation timing using the target velocity acquired based on the target observation image (see FIG. 15B). This timing is obtained by adding a delay time derived by calculation to the reference timing signal. The delay time is the time from the acquisition time of the image shown in FIG. 15B to the time when the target droplet 7 represented in the image reaches the center of the ideal light emission point. This is determined based on the distance between the image acquisition point and the ideal light emission point and the target speed.

  The laser irradiation timing calculated in this way is output to the laser control device 83. The laser control device 83 controls the laser excitation intensity / timing adjustment device 84 according to the laser irradiation timing to emit laser light from the laser light source 42 at a predetermined timing. Thereby, it is possible to perform laser irradiation at a time synchronized with a repetition frequency that is a fraction of the target emission interval and at the time when the droplet target is present at the ideal light emitting point.

Next, the control operation of the laser irradiation point (plasma emission point) in the EUV light source apparatus shown in FIG. 14 will be described.
The EUV light source control device 10 controls the laser irradiation point (plasma emission point) based on the plasma observation image output from the plasma position / timing monitor device 86. The details of the control method are the same as those in the EUV light source apparatus shown in FIG. Here, in the process of making the plasma emission point coincide with the ideal emission point, it is desirable to adjust the delay time so that the laser irradiation is performed at the time when the droplet target 7 reaches the center of the ideal emission point. Thereby, the timing is adjusted so that the center of the plasma image is positioned at the ideal light emission point. In that case, the control may be performed with reference to the EUV energy value.

In the EUV light source device shown in FIGS. 1 and 14 described above, various applications can be applied to the components (devices) constituting the light source device. Below, the application example is demonstrated.
(1) Target position monitoring device The liquefied xenon target flow that is the observation target of the target position monitoring device 31 shown in FIG. 1 or the liquefied xenon droplet target that is the observation target of the target position / velocity monitoring device 82 shown in FIG. Has a diameter of about several tens of μm, for example. When observing such a small object that does not emit light, the field of view may be dark and the contrast between the object and the background may not be sufficient. In such a case, as shown in FIG. 16, it is effective to irradiate the vicinity of the observation target portion by using the high-intensity illumination 301. Further, when the visual field of the target position monitoring device 31 is close to the plasma 2, the plasma 2 may be replaced with illumination.

Alternatively, as shown in FIG. 17, the light amount incident on the image sensor may be increased by disposing a condensing optical system 302 in front of the image sensor (CCD or the like) of the target position monitor 31. In this case, there is no possibility that the flow of the target 1 is disturbed by the heat of illumination.
Further, as shown in FIG. 18, backlight illumination may be achieved by arranging a light source 303 having a strong directivity such as a visible laser outside the EUV chamber 11. In this case, since the components arranged in the EUV chamber 11 can be reduced, it is desirable from the viewpoint of improving the degree of vacuum and reducing impurities. 16 to 18 show a target flow as a target, the same effect can be obtained even when a droplet target is used.

(2) Target Position Monitor Device and Plasma Monitor Device In FIG. 1, an image sensor such as a CCD is used as the target position monitor device 31, and an image sensor such as a CCD with an optical filter disposed on the front surface as the plasma monitor device 51 ( 3) is used. Further, in order to determine the two-dimensional position of the target or plasma, the devices 31 and 51 are arranged at two or more positions. FIG. 19 shows an application example in which such a target position monitoring device 31 and a plasma monitoring device 51 are combined.

  As shown in FIG. 19, an image sensor 310 such as a CCD is a target and a monitor for observing plasma, and is arranged so that both the target 1 and the plasma 2 can be accommodated in the field of view. An optical bandpass filter 311 provided with a drive mechanism is disposed on the front surface of the image sensor 310. When observing both the target 1 and the plasma 2, as shown in FIG. 19A, the optical bandpass filter 311 is used to receive light from plasma on the light receiving surface of the image sensor 310 (in the figure, Is arranged only in the lower half) so that the light from the target 1 and the light from the plasma 2 are almost the same amount. The image representing the target 1 and the image representing the plasma 2 obtained thereby are used in the EUV light source control device 10 for target position control and plasma position control, respectively. On the other hand, when the reference laser beam is observed during the initial alignment, as shown in FIG. 19B, the ideal light emission in which the two reference lasers intersect by retracting the optical bandpass filter 311 from the optical path. The point is set within the field of view of the image sensor 310.

  In this way, by combining the two types of monitor devices, the configuration of the device can be simplified, and the number of imaging elements can be reduced, so that the load on image processing in the EUV light source control device 10 can be reduced. If it is difficult to adjust the light quantity of the light from the target 1 and the light from the plasma 2 even if the optical bandpass filter 311 is used, the target 1 is mounted as shown in FIG. You may apply the structure which illuminates, or the structure which condenses the light from the target 1, as shown in FIG.

(3) IF position sensor As the IF position sensor 62 shown in FIGS. 1 and 14, a CCD having a mirror used for a commercially available EUV pinhole camera or the like is generally used. It may be used.
The IF position sensor shown in FIG. 20 includes an image sensor 620 such as a CCD, a transmission X-ray fluorescent plate 621 provided on the front surface thereof, and a band pass filter 622. As the band-pass filter 622, an EUV transmission filter such as a zirconium (Zr) filter is used. In this IF position sensor, EUV light transmitted through the band-pass filter 622 is converted into visible light by the transmission X-ray fluorescent plate 621, and the visible light is detected by the image sensor 620. According to such a configuration, since a commercially available large CCD can be used as the image sensor 620, there is an advantage that high resolution can be obtained in a large area. That is, the accuracy of IF position control can be greatly improved. In addition, since EUV light is converted into visible light, an image sensor other than a CCD can be used like a CMOS, so that the price of the apparatus can be reduced.

  In the IF position sensor shown in FIG. 21, a reflective X-ray fluorescent plate 623 is arranged instead of the transmissive X-ray fluorescent plate 621 shown in FIG. That is, the image sensor 620 detects visible light reflected from the reflective X-ray fluorescent plate 623. The advantage of using the X-ray fluorescent plate is the same as that in the IF position sensor shown in FIG.

(4) Calibration method of EUV energy monitor device As a method different from the calibration method of EUV energy monitor device 50 described above, the EUV energy monitor device 50 is calibrated without inserting the EUV diode 63 into the exposure optical path. Is also possible.
As shown in FIG. 22A, the collector mirror 13 maintains the position and posture adjusted so as to form a focal point at the ideal condensing point while performing exposure in the exposure apparatus. At that time, the IF position sensor 62 or the EUV diode 63 is retracted from the optical path of the EUV light. On the other hand, as shown in FIG. 22B, when the EUV energy monitor device 50 and the like are calibrated, the collector mirror 13 is slightly tilted. Then, the IF position sensor 62 or the EUV diode 63 is arranged near the condensing point of the collector mirror 13 at that time, and in this state, the output of the EUV energy monitor device 50 and the output of the IF position sensor 62 or the EUV diode Calibrate 63 outputs.
According to such a calibration method, it is not necessary to move the IF position sensor 62 and the EUV diode 63. Accordingly, it is possible to simplify the apparatus configuration of the connection portion with the exposure apparatus whose space is easily limited mechanically.

  Alternatively, as shown in FIG. 23, the IF position sensor 62 or the EUV diode 63 may be disposed inside the EUV chamber 11, and a calibration mirror 64 provided with a drive mechanism may be added. As shown in FIG. 23A, the calibration mirror 64 is retracted from the optical path of the collected light by the collector mirror 13 while exposure is performed in the exposure apparatus. On the other hand, as shown in FIG. 23B, when the EUV energy monitor device 50 and the like are calibrated, a calibration mirror 64 is inserted into the optical path of the condensed light by the collector mirror 13. As a result, the condensed light is reflected and enters the IF position sensor 62 or the EUV diode 63. In this state, the output from the EUV energy monitor device 50 and the calibration of the IF position sensor 62 or the EUV diode 63 are performed. be able to.

  According to the configuration shown in FIG. 23, the apparatus configuration of the connection portion between the EUV chamber 11 and the exposure apparatus can be extremely simplified, and the design of the apparatus becomes easy. When this configuration is used, the IF position sensor 62 or the EUV diode 63 receives light that has not passed through the EUV filter 14, so that the EUV light energy is observed in order to observe the EUV light energy. It is necessary to provide a filter. Further, when this configuration is used, the degree of deterioration of the EUV filter cannot be determined.

(5) Method for detecting the position and orientation of the collector mirror Normally, when exposure is performed in an exposure apparatus, the IF position sensor 62 is retracted from the optical path, so that fluctuations in the focal point cannot be observed. . Therefore, the position and posture of the collector mirror 13 cannot be adjusted during exposure. However, by using the configuration described below, it is possible to detect the displacement of the collector mirror even during exposure.

  As shown in FIG. 24A, around the collector mirror 13, a set of calibration mirrors 65, an image sensor 612 of the collector mirror displacement monitor device 61 (see FIG. 4), an inclination detection light source 613, an inclination A reference reflection surface for detection 614 and an IF position sensor 62 are arranged. FIG. 24B shows a state where the collector mirror 13 is viewed from the condensing point direction. As shown in FIG. 24B, the calibration mirror 65 is disposed so as to surround the collector mirror 13.

  The calibration mirror 65 is adjusted in position and posture so that EUV light that is not used for exposure is condensed at a position Q slightly shifted from a condensing point P of EUV light used for exposure. . Further, the IF position sensor 62 is disposed at the condensing point Q of the calibration mirror 65. By observing the condensing point Q by the IF position sensor 62, the fluctuation of the condensing point P is indirectly detected. Thereby, the displacement of the collector mirror 13 can be detected.

  The image sensor 612 detects light emitted from the tilt detection light source 613 and reflected from the tilt detection reference reflection surface 614. Thereby, the inclination (angle) of the collector mirror 13 is detected. In FIG. 24A, the laser displacement meter 611 shown in FIG. 4 is not shown in this calibration method. In this calibration method, the image information acquired by the IF position sensor 62 is used instead of the laser displacement meter 611. This is because the position of the collector mirror 13 can be detected based on the above. On the other hand, since it is difficult to detect the inclination of the collector mirror 13 from the image information acquired by the IF position sensor 62, the image sensor 612 and the like are also used in the configuration shown in FIG. However, if the resolution of the IF position sensor 62 is high enough to detect the tilt of the collector mirror 13, the image sensor 612 and the like may be omitted.

  According to the configuration shown in FIG. 24, since the position and orientation of the collector mirror 13 can be detected even during exposure, the position and orientation of the collector mirror 13 can be adjusted. Further, since the laser displacement meter 611 (see FIG. 4) of the collector mirror displacement monitor device 61 can be omitted, the device configuration can be simplified.

Further, in the configuration shown in FIG. 24, the IF position sensor 62 is moved to the ideal condensing point, and calibration is made between the actual condensing point and the output image from the IF position sensor 62 at the time of exposure. Thus, the detection accuracy of the displacement of the collector mirror 13 can be increased.
Note that according to the configuration shown in FIG. 24, it is possible to indirectly estimate the damage to the collector mirror 13 based on the image information of the condensed light reflected by the calibration mirror 65. For example, when the light amount of the collected light from the calibration mirror 65 decreases, it is estimated that the reflectance of the collector mirror 13 has decreased.

  Alternatively, as another configuration that enables detection of the position and orientation of the collector mirror even during exposure, the configuration shown in FIG. As shown in FIG. 25A, in this configuration, a plurality of calibration mirrors 66 and a plurality of IF position sensors 62 are used. FIG. 25B shows the collector mirror 13 as viewed from the condensing point direction. As shown in FIG. 25B, the plurality of calibration mirrors 66 are arranged so as to surround the collector mirror 13.

Each calibration mirror 66 collects EUV light that is not used for exposure at positions Q ₁ , Q ₂ ,... Slightly shifted from the condensing point P of EUV light used for exposure. The position and posture are adjusted. Further, the IF position sensor 62 is arranged at the condensing points Q ₁ , Q ₂ ,... Of the corresponding calibration mirror 66. As described above, by using the plurality of IF position sensors 62, it is possible to improve the detection accuracy of the fluctuation of the condensing point P detected indirectly.

Further, by using a short focus mirror as the calibration mirror 66 and disposing the IF position sensor in the vicinity of the focal point, it becomes possible to easily detect a change in the tilt of the mirror. In this case, there is no need to dispose a non-contact sensor (such as the image sensor 612 shown in FIG. 24) for tilt detection.
Further, in this case, the IF position sensor 62 is moved to the ideal condensing point, and a calibration is made between the actual condensing point and the output image from the IF position sensor at the time of exposure. The detection accuracy of the displacement of the mirror 13 can be increased. It is also possible to estimate the damage to the collector mirror 13 based on the image information of the condensed light from the calibration mirror 66.

  In the above, the case where the target flow or the droplet target is formed has been described, but the present invention can also be applied to the case where a gaseous target is used. Examples of the gaseous target include a gas puff target and a tape-like or linear target. Here, the gas puff target is a gaseous target that is intermittently ejected using a pulse valve or the like. When a gaseous target is used, metal powder or the like may be mixed into the gas flow with the aim of improving EUV conversion efficiency.

  The present invention can be used in an initial alignment method in an extreme ultra violet (EUV) light source device used as a light source of an exposure apparatus.

It is a schematic diagram which shows the structure of the EUV light source device to which the initial alignment method of the EUV light source device which concerns on the 1st-4th embodiment of this invention is applied. It is a schematic diagram which shows the target position adjustment apparatus shown in FIG. 1, and its peripheral part. It is a schematic diagram which shows the structure of a plasma monitor apparatus. It is a schematic diagram which shows the collector mirror shown in FIG. 1, and its peripheral part. It is a figure which shows the positional relationship of IF position sensor and EUV filter which are shown in FIG. It is a figure for demonstrating the initial alignment method which concerns on the 1st and 2nd embodiment of this invention. It is a schematic diagram which shows the mode of the EUV chamber and its periphery at the time of initial alignment. It is a flowchart which shows the initial alignment method of the EUV light source device which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the initial alignment method of the EUV light source device which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the initial alignment method of the EUV light source device which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the initial alignment method of the EUV light source device which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the control system in the EUV light source device shown in FIG. It is a block diagram which shows the modification of the control system in the EUV light source device shown in FIG. It is a schematic diagram which shows the structure of the EUV light source device which inject | emits a droplet target. It is a schematic diagram which shows the structural example of the target position and speed monitor apparatus shown in FIG. It is a schematic diagram which shows the structural example of the target position monitoring apparatus shown in FIG.1 and FIG.14. It is a schematic diagram which shows the structural example of the target position monitoring apparatus shown in FIG.1 and FIG.14. It is a schematic diagram which shows the structural example of the target position monitoring apparatus shown in FIG.1 and FIG.14. It is a schematic diagram which shows the structural example which combines the target position monitor apparatus and plasma monitor apparatus which are shown in FIG. It is a schematic diagram which shows the structural example of IF position sensor shown in FIG.1 and FIG.14. It is a schematic diagram which shows the structural example of IF position sensor shown in FIG.1 and FIG.14. It is a figure for demonstrating another method of calibrating an EUV energy monitor apparatus. It is a figure for demonstrating another method of calibrating an EUV energy monitor apparatus. It is a schematic diagram which shows the apparatus structural example for detecting the position and attitude | position of a collector mirror. It is a schematic diagram which shows another apparatus structural example for detecting the position and attitude | position of a collector mirror.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Target, 2 ... Plasma, 3 ... Excitation laser beam, 4, 5 ... Reference laser beam, 7 ... Droplet target, 10 ... EUV light source control apparatus, 11 ... EUV chamber, 12 ... Window, 13 ... Collector Mirror, 14 ... EUV filter, 20 ... Target control device, 21 ... Target supply device, 22 ... Target temperature / pressure (flow rate) adjustment device, 23 ... Target injection device, 30 ... Target position adjustment device, 31 ... Target position monitoring device DESCRIPTION OF SYMBOLS 31, 40 ... Laser control apparatus, 41 ... Laser excitation intensity adjustment apparatus, 42 ... Laser light source, 43 ... Laser energy monitoring apparatus, 44 ... Optical system, 45 ... Condensing element (condensing lens), 46 ... Laser focus adjustment apparatus 50 ... EUV energy monitor device, 51 ... Plasma monitor device, 60 ... Collector mirror drive device, 61 ... RECTOR MIRROR DISPLACEMENT MONITOR DEVICE, 62 ... IF POSITION SENSOR, 63 ... EUV DIODE, 70, 72 ... REFERENCE LASER LIGHT SOURCE, 71, 73 ... OPTICAL SYSTEM, 80 ... TARGET CONTROL DEVICE, 81 ... TARGET Ejection Timing Adjustment Device, 82 ... TARGET Position / velocity monitoring device 83 ... Laser control device 84 ... Laser excitation intensity / timing adjustment device 85 ... Laser energy / timing monitoring device 86 ... Plasma position / timing monitoring device 301 ... Illumination 302 ... Condensing optical system , 303 ... Light source, 310 ... Image sensor, 311 ... Optical band pass filter, 601 ... Collector mirror controller, 602 ... XYZ stage, 603 ... Θ stage, 604 ... β stage, 611 ... Laser displacement meter, 612 ... Image sensor, 613: Light source for tilt detection, 614: Reference reflective surface for tilt detection, 20 ... imaging element, 621 ... transmission type X-ray fluorescent screen, 622 ... bandpass filter, 623 ... reflection type X-ray fluorescent screen, 801, 802 ... High-speed CCD camera

Claims (10)

Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
A first position reference element is disposed at an ideal light emission point that is a position where the plasma is to be generated, and a second position reference element is disposed at an ideal light collection point where the light generated from the plasma is to be collected. Step (a)
The optical path of the first optical axis adjustment light is adjusted and the second optical axis adjustment is performed so that the first optical axis adjustment light passes through the first position reference element and the second position reference element. An optical path of the second optical axis adjustment light is adjusted so that light does not pass through the first position reference element and does not pass through the second position reference element, and a sensor near the ideal condensing point is used. Obtaining the image information of the first optical axis adjustment light (b),
Emitted the laser light from the target excitation laser light source, such that the laser light irradiating the first position reference device through a laser beam condensing device, adjust the position and orientation of the laser beam condensing device Performing step (c);
While emitting the first retracted position reference elements Rutotomoni said first and second optical axis adjustment light, supplying the target material inside the vacuum chamber using a target injection device, the as target material through an intersection point between the second optical axis adjustment light and the first optical axis adjustment light, the step (d) to adjust the position and orientation of the target injection device,
Wherein said first and a state of being retracted second position reference element, the said laser beam emitted from the target excitation laser source target while the first and stop emission of the second optical axis adjustment light Irradiating the substance (e);
The extreme image information of ultraviolet light obtained using the sensor image information and the polar ends of the first optical axis adjustment light for generating the laser beam from the plasma generated by irradiating the target material A step (f) of adjusting the position and orientation of the EUV collector mirror so that the extreme ultraviolet light is condensed at the ideal condensing point by the EUV collector mirror based on the image information of the ultraviolet light; When,
An alignment method for an extreme ultraviolet light source device comprising: Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
A first position reference element is disposed at an ideal light emission point that is a position where the plasma is to be generated, and a second position reference element is disposed at an ideal light collection point where the light generated from the plasma is to be collected. Step (a)
Emitted the laser light from the target excitation laser light source, such that the laser light irradiating the first position reference device through a laser beam condensing device, adjust the position and orientation of the laser beam condensing device Step (b),
The optical path of the first optical axis adjustment light is adjusted and the second optical axis adjustment is performed so that the first optical axis adjustment light passes through the first position reference element and the second position reference element. An optical path of the second optical axis adjustment light is adjusted so that light does not pass through the first position reference element and does not pass through the second position reference element, and a sensor near the ideal condensing point is used. Obtaining the image information of the first optical axis adjusting light (c),
While emitting the first retracted position reference elements Rutotomoni said first and second optical axis adjustment light, supplying the target material inside the vacuum chamber using a target injection device, the as target material through an intersection point between the second optical axis adjustment light and the first optical axis adjustment light, the step (d) to adjust the position and orientation of the target injection device,
Wherein said first and a state of being retracted second position reference element, the said laser beam emitted from the target excitation laser source target while the first and stop emission of the second optical axis adjustment light Irradiating the substance (e);
The extreme image information of ultraviolet light obtained using the sensor image information and the polar ends of the first optical axis adjustment light for generating the laser beam from the plasma generated by irradiating the target material A step (f) of adjusting the position and orientation of the EUV collector mirror so that the extreme ultraviolet light is condensed at the ideal condensing point by the EUV collector mirror based on the image information of the ultraviolet light; When,
An alignment method for an extreme ultraviolet light source device comprising: Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
A first position reference element is disposed at an ideal light emission point that is a position where the plasma is to be generated, and a second position reference element is disposed at an ideal light collection point where the light generated from the plasma is to be collected. And (a) disposing a third position reference element on a straight line connecting the ideal light emission point and the ideal light collection point on the opposite side of the ideal light emission point when viewed from the ideal light collection point. When,
As the first optical axis adjustment light passes through said third position reference device before Symbol first or second position reference elements, thereby adjusting the optical path of the first optical axis adjustment light, the as the second optical axis adjustment light passes through the first position reference element does not pass the second position reference elements, to adjust the optical path of the second optical axis adjustment light, the ideal focal point (B) obtaining image information of the first optical axis adjustment light using a nearby sensor ;
Emitted the laser light from the target excitation laser light source, such that the laser light irradiating the first position reference device through a laser beam condensing device, adjust the position and orientation of the laser beam condensing device Performing step (c);
While emitting the first retracted position reference elements Rutotomoni said first and second optical axis adjustment light, supplying the target material inside the vacuum chamber using a target injection device, the as target material through an intersection point between the second optical axis adjustment light and the first optical axis adjustment light, the step (d) to adjust the position and orientation of the target injection device,
Wherein said first and a state of being retracted second position reference element, the said laser beam emitted from the target excitation laser source target while the first and stop emission of the second optical axis adjustment light Irradiating the substance (e);
The laser beam is obtained using the sensor image information of the extreme ultraviolet light generated from the generated the plasma by irradiating the target material, and the data of the image information of the first optical axis adjustment light Based on the image information data of the extreme ultraviolet light , the position and orientation of the EUV collector mirror are adjusted so that the extreme ultraviolet light is condensed at the ideal focal point by the EUV collector mirror. Step (f);
An alignment method for an extreme ultraviolet light source device comprising: Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
A first position reference element is disposed at an ideal light emission point that is a position where the plasma is to be generated, and a second position reference element is disposed at an ideal light collection point where the light generated from the plasma is to be collected. And (a) disposing a third position reference element on a straight line connecting the ideal light emission point and the ideal light collection point on the opposite side of the ideal light emission point when viewed from the ideal light collection point. When,
Emitted the laser light from the target excitation laser light source, such that the laser light irradiating the first position reference device through a laser beam condensing device, adjust the position and orientation of the laser beam condensing device Step (b),
As the first optical axis adjustment light passes through said third position reference device before Symbol first or second position reference elements, thereby adjusting the optical path of the first optical axis adjustment light, the as the second optical axis adjustment light passes through the first position reference element does not pass the second position reference elements, to adjust the optical path of the second optical axis adjustment light, the ideal focal point (C) acquiring image information of the first optical axis adjustment light using a nearby sensor ;
While emitting the first retracted position reference elements Rutotomoni said first and second optical axis adjustment light, supplying the target material inside the vacuum chamber using a target injection device, the as target material through an intersection point between the second optical axis adjustment light and the first optical axis adjustment light, the step (d) to adjust the position and orientation of the target injection device,
Wherein said first and a state of being retracted second position reference element, the said laser beam emitted from the target excitation laser source target while the first and stop emission of the second optical axis adjustment light Irradiating the substance (e);
The extreme image information of ultraviolet light obtained using the sensor image information and the polar ends of the first optical axis adjustment light for generating the laser beam from the plasma generated by irradiating the target material A step (f) of adjusting the position and orientation of the EUV collector mirror so that the extreme ultraviolet light is condensed at the ideal condensing point by the EUV collector mirror based on the image information of the ultraviolet light; When,
An alignment method for an extreme ultraviolet light source device comprising: After step (c), an alignment method of an extreme ultraviolet light source device according to claim 1-4 set forth in any one of further comprising the step of stopping the injection of the laser light from the target excitation laser light source. Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
The first positional reference element disposed on the ideal emission point is a position to be generated the plasma, distribution a second position reference elements the light generated from the plasma to the ideal focal point is a position to be focused and step (a) you location,
As the first optical axis adjustment light passes in front Symbol first position reference element and the second position reference element, thereby adjusting the optical path of the first optical axis adjustment light, the second light A sensor in the vicinity of the ideal condensing point is adjusted by adjusting the optical path of the second optical axis adjusting light so that the axis adjusting light does not pass through the first position reference element and does not pass through the second position reference element. (B) acquiring image information of the first optical axis adjustment light using
While emitting the first retracted position reference elements Rutotomoni said first and second optical axis adjustment light, supplying the target material inside the vacuum chamber using a target injection device, the as target material through an intersection point between the second optical axis adjustment light and the first optical axis adjustment light, the step (c) to adjust the position and orientation of the target injection device,
Wherein said first and a state of being retracted second position reference element, the said laser beam emitted from the target excitation laser source target while the first and stop emission of the second optical axis adjustment light Irradiating the substance (d);
The laser beam obtained using sensor image information of the generated said plasma of said near ideal light emission point by irradiating the target material, based on the image information of the plasma, the laser beam is laser beam focusing Adjusting the position and orientation of the laser beam condensing element so as to irradiate the ideal light emitting point via an optical element;
The laser beam is obtained using the extreme ultraviolet sensor of the ideal current near point image information generated from the plasma generated by irradiating the target material, the first optical axis adjustment light And the position and posture of the EUV collector mirror so that the extreme ultraviolet light is collected at the ideal focal point by the EUV collector mirror based on the image information of the extreme ultraviolet light and the image information of the extreme ultraviolet light. Adjusting step (f);
An alignment method for an extreme ultraviolet light source device comprising: Step (f) adjusts the position and orientation of the EUV collector mirror so that the optical axis of the light collected by the EUV collector mirror passes through the ideal emission point and the ideal collection point. The alignment method of the extreme ultraviolet light source device according to any one of claims 1 to 6 , comprising: Step (f) includes adjusting the position and orientation of the EUV collector mirror so that the light collected by the EUV collector mirror is collected at the ideal focal point with a minimum spot diameter. , alignment method of an extreme ultraviolet light source device of any one of claims 1-7. Plasma is generated by irradiating the target material supplied to the inside of the vacuum chamber with laser light for exciting the target material, and extreme ultraviolet (EUV) light generated from the plasma is predetermined by the EUV collector mirror. An alignment method of an extreme ultraviolet light source device using a laser-excited plasma system that focuses light at a position of
A first position reference element is disposed at an ideal light emission point that is a position where the plasma is to be generated, and a second position reference element is disposed at an ideal light collection point where the light generated from the plasma is to be collected. And (a) disposing a third position reference element on a straight line connecting the ideal light emission point and the ideal light collection point on the opposite side of the ideal light emission point when viewed from the ideal light collection point. When,
As the optical axis adjustment light passes through said third position reference device before Symbol first or second position reference element, and step (b) for adjusting an optical path of the optical axis adjustment light,
In a state of being retracted first position reference elements, arranged scattering body to the ideal light emitting point, the ideal focal point is scattered the optical axis adjustment light by the EUV collector mirror by the scatterer (C) adjusting the position and posture of the EUV collector mirror so as to be focused on
An alignment method for an extreme ultraviolet light source device comprising: The optical axis adjustment light source is a visible light source, an alignment method of an extreme ultraviolet light source device of any one of claims 1-9.