阅读说明：本技术 一种椭球反射镜位置调整装置及调整方法 (Position adjusting device and method for ellipsoidal reflector ) 是由 刘风秀 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种椭球反射镜位置调整装置及调整方法,椭球反射镜位置调整装置包括：内调焦望远镜、受光屏、光源、光源标定版、灯室位置标定版、灯室基准固定板和五维调整机构；灯室基准固定板位于光学平台上,灯室位置标定版固定在灯室基准固定板上；五维调整机构位于灯室位置标定版上侧；光源标定版位于五维调整机构上侧；受光屏位于光源上侧；内调焦望远镜将光源、灯室位置标定版的标记中心和受光屏的标记中心调整至同一光轴；五维调整机构对椭球反射镜进行调节,使得光源位于椭球反射镜的实际第一焦点处,且受光屏的标记中心位于椭球反射镜的实际第二焦点处。本发明提供的技术方案,以解决椭球反射镜的位置调整精度低、调整复杂的问题。(The invention discloses an ellipsoidal reflector position adjusting device and an ellipsoidal reflector position adjusting method, wherein the ellipsoidal reflector position adjusting device comprises: the device comprises an internal focusing telescope, a light receiving screen, a light source calibration plate, a lamp chamber position calibration plate, a lamp chamber reference fixing plate and a five-dimensional adjusting mechanism; the lamp chamber reference fixing plate is positioned on the optical platform, and the lamp chamber position calibration plate is fixed on the lamp chamber reference fixing plate; the five-dimensional adjusting mechanism is positioned on the upper side of the lamp room position calibration plate; the light source calibration plate is positioned on the upper side of the five-dimensional adjusting mechanism; the light receiving screen is positioned on the upper side of the light source; the inner focusing telescope adjusts the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis; the five-dimensional adjusting mechanism adjusts the ellipsoidal reflector so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at an actual second focus of the ellipsoidal reflector. The technical scheme provided by the invention aims to solve the problems of low position adjustment precision and complex adjustment of the ellipsoidal reflector.)

1. An ellipsoidal reflector position adjustment device, comprising: the device comprises an internal focusing telescope, a light receiving screen, a light source calibration plate, a lamp chamber position calibration plate, a lamp chamber reference fixing plate and a five-dimensional adjusting mechanism;

the lamp chamber reference fixing plate is arranged on one side of the optical platform; the lamp room position calibration board is fixed on the lamp room reference fixing plate and used for setting a mark to calibrate the position of the lamp room; the five-dimensional adjusting mechanism is arranged on one side, away from the optical platform, of the lamp room position calibration plate and used for placing the ellipsoidal reflector and adjusting the position of the ellipsoidal reflector; the light source calibration plate is arranged on one side, away from the optical platform, of the five-dimensional adjusting mechanism and is used for setting a mark to calibrate the installation position of the light source; the light receiving screen is arranged on one side of the light source, which is far away from the optical platform, and is used for setting a mark to mark the position of the light receiving screen;

the inner focusing telescope is used for adjusting the light source, the mark center of the lamp room position calibration plate and the mark center of the light receiving screen to the same optical axis to form a reference optical axis; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a theoretical second focus of the ellipsoidal reflector;

the five-dimensional adjusting mechanism is further used for adjusting the position of the ellipsoidal reflector, so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at an actual second focus of the ellipsoidal reflector.

2. The ellipsoidal reflector position adjustment device of claim 1, further comprising: a plane mirror;

the plane reflector is arranged on one side of the light source, which is far away from the optical platform, and is used for reflecting the emergent light of the light source and the reflected light of the ellipsoidal reflector to the light receiving screen.

3. The ellipsoidal reflector position adjustment device of claim 1, wherein:

the marks of the light source calibration plate, the marks of the lamp chamber position calibration plate and the marks of the light receiving screen are all cross-shaped.

4. A method for adjusting the position of an ellipsoidal reflector, which is applied to the ellipsoidal reflector position adjusting device according to any one of claims 1 to 3, the method comprising:

adjusting the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis through the inner focusing telescope to form a reference optical axis; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a theoretical second focus of the ellipsoidal reflector;

the five-dimensional adjusting mechanism is further used for adjusting the position of the ellipsoidal reflector, so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at an actual second focus of the ellipsoidal reflector.

5. The ellipsoidal reflector position adjustment method of claim 4,

adjusting the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis through the inner focusing telescope to form a reference optical axis; and the light source is positioned at the theoretical first focus of the ellipsoidal reflector, and the mark center of the light-receiving screen is positioned at the second focus, and the method comprises the following steps:

focusing the inner focusing telescope to infinity and providing a calibration light beam;

sequentially adjusting the positions of the lamp room position calibration plate, the light source calibration plate and the light receiving screen; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a second focus;

adjusting the position between each mark and the cross division plate of the inner focusing telescope to meet the condition that Rx is smaller than a first angle threshold value, Ry is smaller than a second angle threshold value, Dx is smaller than a first distance threshold value, and Dy is smaller than a second distance threshold value; the cross-shaped division plate forms a first coordinate system which takes a cross center as an origin, one scribing line as an abscissa axis and the other scribing line as an ordinate axis, and Rx is an included angle between a plane where the mark is located and the abscissa axis of the first coordinate system; ry is an included angle between the plane where the mark is located and the ordinate axis of the first coordinate system; dx is the offset of the orthographic projection of the marking center and the origin of the first coordinate system in the abscissa axis direction, and Dy is the offset of the orthographic projection of the marking center and the origin of the first coordinate system in the ordinate axis direction;

and locking the positions of the lamp room position calibration plate, the light source calibration plate and the light receiving screen, so that the marking centers of the light source, the lamp room position calibration plate and the light receiving screen are adjusted to be the same optical axis to form a reference optical axis.

6. The ellipsoidal reflector position adjustment method of claim 5, further comprising, before adjusting the positions of the lamp chamber position calibration plate, the light source calibration plate, and the light-receiving screen in sequence:

mounting the lamp chamber position calibration plate on the lamp chamber reference fixing plate;

and placing the lamp chamber reference fixing plate on an optical platform, and adjusting the lamp chamber reference fixing plate through the lamp chamber position calibration plate.

7. The ellipsoidal reflector position adjustment method of claim 5,

the first angle threshold is less than or equal to 15 μ rad, the second angle threshold is less than or equal to 15 μ rad, the first distance threshold is less than or equal to 10 μm, and the second distance threshold is less than or equal to 10 μm.

8. The ellipsoidal reflector position adjustment method of claim 4, wherein the five-dimensional adjustment mechanism is further configured to adjust the position of the ellipsoidal reflector such that the light source is located at an actual first focus of the ellipsoidal reflector and the marked center of the light-receiving screen is located at an actual second focus of the ellipsoidal reflector, comprising:

an ellipsoidal reflecting mirror is arranged on the five-dimensional adjusting mechanism; starting the light source, and acquiring light source imaging on the light receiving screen; a second coordinate system taking the first direction as an abscissa axis and the second direction as an ordinate axis is formed in the plane of the light receiving screen; the first direction is perpendicular to the second direction; the origin of the second coordinate system is located on the reference optical axis;

moving the light source imaging to an origin covering the second coordinate system, and acquiring coordinates of an intersection point of the light source imaging and the second coordinate system: a first position coordinate (X1, 0), a second position coordinate (-X2, 0), a third position coordinate (0, Y1), a fourth position coordinate (0, -Y2); x1, X2, Y1 and Y2 are positive numbers;

adjusting the position of the ellipsoidal mirror in a plane perpendicular to the reference optical axis such that | X1-X2| < d1, | Y1-Y2| < d 2; d1 is the lateral offset threshold, d2 is the longitudinal offset threshold;

adjusting the included angle of the ellipsoidal reflector and a plane perpendicular to the reference optical axis to enable | (X1-X2) - (Y1-Y2) | < d 3; d3 is the overall offset threshold;

by adjusting the position of the ellipsoidal mirror in a plane parallel to the reference optical axis such that d4< X1+ X2< d5, d6< Y1+ Y2< d 7; d4 is the first size threshold, d5 is the second size threshold, d6 is the third size threshold, d7 is the fourth size threshold;

and locking the position of the ellipsoidal reflector, wherein the light source is positioned at the actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at the actual second focus of the ellipsoidal reflector.

9. The ellipsoidal reflector position adjustment method of claim 7, wherein the maximum size of the light source is 1 mm;

d1 is less than or equal to 0.1mm, d2 is less than or equal to 0.1mm, and d3 is less than or equal to 0.1 mm.

Technical Field

The invention relates to the technical field of photoetching, in particular to a device and a method for adjusting the position of an ellipsoidal reflector.

Background

The ellipsoidal reflector is widely applied to the field of illumination, and in high and new technologies such as application of a projection objective photoetching machine adopting mercury lamp illumination, higher illumination and illumination uniformity are required, and the ellipsoidal reflector has higher requirements on design and adjustment precision.

In general, in a mercury lamp chamber of a lithography machine, light emitted from a mercury lamp is projected to a light exit side after passing through the ellipsoidal mirror and the plane mirror to form a light cone, and the light cone is used as an illumination light source. However, the light cone needs to satisfy a certain eccentricity and inclination angle relative to the external interface of the lamp chamber so as to satisfy the assembly requirements of the lamp chamber and other components. However, due to the machining matching error of each part in the lamp chamber, the light cone emitted by the lamp chamber cannot meet the precision requirement. It is necessary to adjust the positions of the ellipsoidal and planar reflectors in the lamp chamber to compensate for machining and assembly errors of the parts and to adjust the light cone of the lamp chamber to within tolerance.

The adjusting method needs more mechanisms to be adjusted, once the lamp chamber has problems and needs to be adjusted again, all structures in the lamp chamber need to be adjusted again, the performance can not be kept consistent after each replacement, the adjusting error is large, the adjustment is complex, the photoetching process is not facilitated, and the process efficiency is reduced.

Disclosure of Invention

The embodiment of the invention provides a position adjusting device and a position adjusting method for an ellipsoidal reflector, and aims to solve the problems that the position adjusting precision of the ellipsoidal reflector is low and the adjusting process is complex.

In a first aspect, an embodiment of the present invention provides a position adjustment device for an ellipsoidal reflector, including: the device comprises an internal focusing telescope, a light receiving screen, a light source calibration plate, a lamp chamber position calibration plate, a lamp chamber reference fixing plate and a five-dimensional adjusting mechanism;

the lamp chamber reference fixing plate is arranged on one side of the optical platform; the lamp room position calibration board is fixed on the lamp room reference fixing plate and used for setting a mark to calibrate the position of the lamp room; the five-dimensional adjusting mechanism is arranged on one side, away from the optical platform, of the lamp room position calibration plate and used for placing the ellipsoidal reflector and adjusting the position of the ellipsoidal reflector; the light source calibration plate is arranged on one side, away from the optical platform, of the five-dimensional adjusting mechanism and is used for setting a mark to calibrate the installation position of the light source; the light receiving screen is arranged on one side of the light source, which is far away from the optical platform, and is used for setting a mark to mark the position of the light receiving screen;

the inner focusing telescope is used for adjusting the light source, the mark center of the lamp room position calibration plate and the mark center of the light receiving screen to the same optical axis to form a reference optical axis; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a theoretical second focus of the ellipsoidal reflector;

the five-dimensional adjusting mechanism is further used for adjusting the position of the ellipsoidal reflector, so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at an actual second focus of the ellipsoidal reflector.

In a second aspect, an embodiment of the present invention further provides a method for adjusting a position of an ellipsoidal reflector, where the method is implemented by using a device for adjusting a position of an ellipsoidal reflector according to any embodiment of the present invention, and the method includes:

adjusting the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis through the inner focusing telescope to form a reference optical axis; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a theoretical second focus of the ellipsoidal reflector;

the five-dimensional adjusting mechanism is further used for adjusting the position of the ellipsoidal reflector, so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at an actual second focus of the ellipsoidal reflector.

In the invention, the position adjusting device of the ellipsoid reflecting mirror comprises a position calibration unit consisting of an inner focusing telescope, a light receiving screen, a light source calibration plate, a light source and a lamp chamber position calibration plate, the light source calibration plate and the light receiving screen are sequentially arranged along the direction far away from an optical platform, the inner focusing telescope adjusts the marking center of the lamp chamber position calibration plate, the marking centers of the light source and the light receiving screen to be adjusted to the same reference optical axis, the light source is arranged at a theoretical first focus of the ellipsoid reflecting mirror, the marking center of the light receiving screen is arranged at a theoretical second focus, on the basis, the ellipsoid reflecting mirror is arranged, the light receiving screen, the light source, a five-dimensional adjusting mechanism and the ellipsoid reflecting mirror form a detection adjusting unit, the position of the ellipsoid reflecting mirror is adjusted by the five-dimensional adjusting mechanism, so that the light source is arranged at the actual first focus of the ellipsoid reflecting mirror, the marking center of the light receiving screen is arranged at the actual second focus, the optical axis of the ellipsoid reflecting mirror is coincided with the reference optical axis, so that the relation between the optical axis of the ellipsoid reflecting mirror and the position of the lamp house is established, the actual optical axis is confirmed, the positioning precision is improved, the integration precision of the exposure subsystem is improved, the emergent light spots of the light source can be adjusted only by adjusting the position of the ellipsoid reflecting mirror after the positions of other components are calibrated, the adjusting process is simple, and the integration efficiency of the lamp house of the exposure subsystem is improved.

Drawings

Fig. 1 is a schematic structural diagram of an ellipsoidal reflector position adjustment device according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another ellipsoidal reflector position adjustment device according to an embodiment of the present invention;

fig. 3 is a schematic flow chart illustrating a method for adjusting the position of an ellipsoidal reflector according to an embodiment of the present invention;

FIG. 4 is a schematic flow chart illustrating another method for adjusting the position of an ellipsoidal reflector according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of another ellipsoidal reflector position adjustment device according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a mark alignment structure according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of another alignment structure of marks according to an embodiment of the present invention;

FIG. 8 is a schematic flow chart illustrating another method for adjusting the position of an ellipsoidal reflector according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of another ellipsoidal reflector position adjustment device provided in an embodiment of the invention;

FIG. 10 is a schematic diagram of a light source imaging structure according to an embodiment of the present invention;

fig. 11 is an optical path diagram of a light source imaging according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In order to obtain a uniform illumination light source for lithography in the prior art, light emitted from the light source needs to be reflected by an ellipsoidal reflector in a lamp chamber to form a light cone with uniform light emission. In order to adjust the light cone in the lamp chamber to be within a tolerance range, the ellipsoidal reflector and each structure in the lamp chamber need to be adjusted simultaneously, more adjusting mechanisms are needed, the more complicated the adjusting process is, the larger the introduced adjusting error is, and the more difficult the adjustment is.

The embodiment of the invention provides a position adjusting device of an ellipsoid reflecting mirror, which can be applied to the adjustment of an illumination light source in a lamp chamber of an exposure subsystem of a photoetching machine, and comprises the following components: the device comprises an internal focusing telescope, a light receiving screen, a light source calibration plate, a lamp chamber position calibration plate, a lamp chamber reference fixing plate and a five-dimensional adjusting mechanism;

the lamp house reference fixing plate is arranged on one side of the optical platform; the lamp chamber position calibration plate is fixed on the lamp chamber reference fixing plate and used for setting a mark to calibrate the position of the lamp chamber; the five-dimensional adjusting mechanism is arranged on one side, away from the optical platform, of the lamp room position calibration plate and used for placing the ellipsoidal reflector and adjusting the position of the ellipsoidal reflector; the light source calibration plate is arranged on one side of the five-dimensional adjusting mechanism, which is far away from the optical platform, and is used for setting a mark to calibrate the installation position of the light source; the light receiving screen is arranged on one side of the light source, which is far away from the optical platform, and is used for setting a mark to mark the position of the light receiving screen;

the inner focusing telescope is used for adjusting the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis to form a reference optical axis; the light source is positioned at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at a theoretical second focus of the ellipsoidal reflector;

the five-dimensional adjusting mechanism is also used for adjusting the position of the ellipsoidal reflector, so that the light source is positioned at the actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at the actual second focus of the ellipsoidal reflector.

In the embodiment of the invention, the position adjusting device of the ellipsoid reflecting mirror comprises a position calibration unit consisting of an inner focusing telescope, a light receiving screen, a light source calibration plate, a light source and a lamp chamber position calibration plate, the light source calibration plate and the light receiving screen are sequentially arranged along the direction far away from an optical platform, the inner focusing telescope adjusts the marking center of the lamp chamber position calibration plate, the marking centers of the light source and the light receiving screen to the same reference optical axis, the light source is arranged at a theoretical first focus of the ellipsoid reflecting mirror, the marking center of the light receiving screen is arranged at a theoretical second focus, on the basis, the ellipsoid reflecting mirror is arranged, the light receiving screen, the light source, a five-dimensional adjusting mechanism and the ellipsoid reflecting mirror form a detection adjusting unit, the position of the ellipsoid reflecting mirror is adjusted through the five-dimensional adjusting mechanism, so that the light source is positioned at the actual first focus of the ellipsoid reflecting mirror, the mark center of the light receiving screen is arranged at the actual second focus, so that the optical axis of the ellipsoidal reflector is superposed with the reference optical axis, the relation between the optical axis of the ellipsoidal reflector and the position of the lamp chamber is established, the actual optical axis is confirmed, the positioning precision is improved, the integration precision of the exposure subsystem is improved, the emergent light spots of the light source can be adjusted only by adjusting the position of the ellipsoidal reflector after the positions of other components are calibrated, the adjusting process is simple, and the integration efficiency of the lamp chamber of the exposure subsystem is improved.

The above is the core idea of the present invention, and the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of an ellipsoidal reflector position adjusting device according to an embodiment of the present invention, and as shown in fig. 1, the ellipsoidal reflector position adjusting device includes an inner focusing telescope 11, a light receiving screen 12, a light source 13, a light source calibration plate 14, a lamp house position calibration plate 17, a lamp house reference fixing plate 19, and a five-dimensional adjusting mechanism 16.

The ellipsoidal reflector 15 can reflect an uneven light source to form an illumination light source with uniform illumination intensity, specifically, the ellipsoidal reflector 15 comprises a first focus and a second focus which are positioned on an optical axis, emergent light rays emitted from the first focus can pass through the second focus, and the illumination intensity of light source images at the second focus is uniform and can be used as an illumination light source of a photoetching process. In this embodiment, the light source 13 can be placed at the first focus, and the light source image of the light source 13 at the second focus can be used as the illumination light source. Optionally, the light source 13 in this embodiment may be a mercury lamp or an LED lamp bead, which is not limited in this embodiment.

The lamp house reference fixing plate 19 is arranged on the optical platform 18; the lamp chamber position calibration plate 17 is disposed on a side of the lamp chamber reference fixing plate 19 away from the optical platform 18, and is fixedly connected to the lamp chamber fixing plate 19. The lamp chamber fixing plate 19 is placed on the bearing surface of the optical platform 18, and the lamp chamber position calibration plate 17 can be fixedly installed, to a certain extent, the lamp chamber reference fixing plate 19 can represent the position of the lamp chamber, the lamp chamber position calibration plate 17 is fixedly connected with the lamp chamber reference fixing plate 19 to establish a relationship, namely, the relationship is established between the lamp chamber position calibration plate 17 and the position of the lamp chamber, and when the lamp chamber reference fixing plate 19 needs to be adjusted, the lamp chamber position calibration plate 17 can be directly adjusted.

The lamp room position calibration board 17 is provided with a mark for calibrating the position of the lamp room, and because the lamp room and other components have assembly requirements, a certain matching requirement is also provided between the lamp room and the ellipsoidal reflector 15, so that the inclination or eccentricity between a lighting source formed by the reflection of the ellipsoidal reflector 15 and an external interface of the lamp room is avoided, and the lamp room position calibration board 17 is arranged for calibrating the position of the lamp room, so that the association between the optical axis of the ellipsoidal reflector 15 and the position of the lamp room is realized.

The five-dimensional adjusting mechanism 16 is arranged on one side of the lamp room position calibration plate 17 far away from the optical platform 18, and is used for placing the ellipsoidal reflector 15 to adjust the position of the ellipsoidal reflector 15, and adjusting the position, the angle, the orientation and the like of the ellipsoidal reflector 15 in multiple dimensions. The light source calibration plate 14 is disposed on a side of the five-dimensional adjustment mechanism 16 away from the optical platform 18, and is provided with a mark to calibrate an installation position of the light source 13, and optionally, the light source 13 may be installed in a mark center of the mark of the light source calibration plate 14, so that the position of the light source calibration plate 14 is adjusted to make the light source 13 located at the first focus of the ellipsoidal reflector 15. The light receiving screen 12 is disposed on a side of the light source 13 away from the optical platform 18, and is provided with a mark to mark a position of the light receiving screen 12, the light receiving screen 12 is used for displaying an imaging effect of the light source, and the present embodiment aims to adjust a center of the mark of the light receiving screen 12 to a second focus of the ellipsoidal reflector 15. Because of the process and material, there is an error between the theoretical position and the actual position of the first focus and the second focus of the ellipsoidal reflector 15, in this embodiment, the light source 13 may be first adjusted to the theoretical first focus of the ellipsoidal reflector 15, and the mark center of the light-receiving screen 12 may be adjusted to the theoretical second focus of the ellipsoidal reflector 15.

The focus of the inner focusing telescope 11 can be adjusted to infinity through the lens inside the lens, so that parallel light rays received by the inner focusing telescope 11 can be approximately identified, and marked plane imaging can be accurately obtained, and the inner focusing telescope is used for adjusting the positions of the lamp room position calibration plate 17, the light source calibration plate 14 and the light receiving screen 12, finally, the light source 13, the marking center of the lamp room position calibration plate 17 and the marking center of the light receiving screen 12 are adjusted to the same optical axis, a reference optical axis L1 is formed, the relation between the reference optical axis L1 of the ellipsoidal reflector 15 and the lamp room is established, the position relation of the whole lamp room and the ellipsoidal reflector position adjusting device is locked, and the integration precision of an exposure subsystem is improved. Optionally, the marks of the lamp room position calibration plate 17, the light source calibration plate 14 and the light receiving screen 12 may be all set at the center of the plane where the light source calibration plate and the light receiving screen are located, so as to improve the accuracy of position adjustment.

Optionally, the marks of the light source calibration plate 14, the light chamber position calibration plate 17, and the light receiving screen 12 may be cross-shaped. The inside focusing telescope 11 is generally provided with a cross-shaped dividing plate, so as to adjust the positions of the above components according to the size and position of the marks, the marks of the components can be cross-shaped to improve the setting precision of the reference optical axis L1, and optionally, the sizes of the marks of the light source calibration plate 14, the marks of the lamp chamber position calibration plate 17 and the marks of the light receiving screen 12 are consistent to further improve the precision of the reference optical axis L1. Of course, the marks of the light source calibration plate 14, the marks of the lamp chamber position calibration plate 17, and the marks of the light receiving screen 12 may have other shapes, such as a triangle, a rectangle, etc., which are not limited in this embodiment.

In summary, on the premise that the ellipsoidal reflector 15 is not installed, the internal focusing telescope 11, the light receiving screen 12, the light source calibration plate 14, the light source 13 and the lamp room position calibration plate 17 may form a position calibration unit for locking the positions of the light receiving screen 12, the light source calibration plate 14 and the lamp room position calibration plate 17 in advance, establishing a reference optical axis L1, and improving the integration precision of the exposure subsystem.

After that, the ellipsoidal reflector 15 is mounted on the five-dimensional adjusting mechanism 16, the inner focusing telescope 11 is removed, the light receiving panel 12, the light source 13, the ellipsoidal reflector 15 and the five-dimensional adjusting mechanism 16 form a detection adjusting unit, the actual optical axis L2 of the ellipsoidal reflector 15 is acquired, the positions of the actual first focus and the actual second focus are acquired, and the ellipsoidal reflector 15 is subjected to position adjustment so that the actual first focus coincides with the theoretical first focus of the reference optical axis L1 and the actual second focus coincides with the theoretical second focus of the reference optical axis L1, thereby realizing coincidence between the actual optical axis L2 of the ellipsoidal reflector 15 and the reference optical axis L1. Therefore, the position adjustment process of the ellipsoidal reflector is completed, so that light source images formed by the light source 13 at the light receiving screen 13 can be accurately transmitted out of an external interface of the lamp chamber, and the integration precision of the exposure subsystem is improved. In the embodiment, the position adjustment accuracy of the ellipsoidal reflector is high, the adjustment accuracy is high, and the integration efficiency of the exposure subsystem is improved.

Fig. 2 is a schematic structural diagram of another ellipsoidal reflector position adjustment device according to an embodiment of the present invention, and optionally, the ellipsoidal reflector position adjustment device may further include: a plane mirror 20; the plane reflector 20 is disposed on a side of the light source 13 away from the optical platform 18, and is configured to reflect the emergent light of the light source 13 and the reflected light of the ellipsoidal reflector 15 to the light receiving panel 12. Referring to fig. 1, the emergent light of the light source 13 and the reflected light of the ellipsoidal reflector 15 can be directly projected to the light receiving screen 12, at this time, the optical axis of the ellipsoidal reflector 15 is linear, but the linear optical axis occupies a larger longitudinal space, in this embodiment, the optical axis direction can be changed by using the plane reflector 20 according to the actual space requirement, so as to reduce the longitudinal space of the ellipsoidal reflector position adjusting device, further improve the occupied volume of the whole exposure subsystem, and improve the integration level of the exposure subsystem.

Based on the same concept, the embodiment of the invention also provides a position adjusting method of the ellipsoidal reflector, which is suitable for the position adjusting device of the ellipsoidal reflector provided by any embodiment of the invention. Fig. 3 is a schematic flow chart of a method for adjusting the position of an ellipsoidal reflector according to an embodiment of the present invention, as shown in fig. 3, the method of the present embodiment includes the following steps:

step S110, respectively adjusting the marking centers of the light source, the lamp room position calibration plate and the light receiving screen to the same optical axis through an internal focusing telescope to form a reference optical axis; and the light source is positioned at the theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at the theoretical second focus of the ellipsoidal reflector.

Step S120, the five-dimensional adjusting mechanism is further configured to adjust the position of the ellipsoidal reflector, so that the light source is located at an actual first focus of the ellipsoidal reflector, and the mark center of the light-receiving screen is located at an actual second focus of the ellipsoidal reflector.

In the embodiment of the invention, the position adjusting device of the ellipsoid reflecting mirror comprises a position calibration unit consisting of an inner focusing telescope, a light receiving screen, a light source calibration plate, a light source and a lamp chamber position calibration plate, the light source calibration plate and the light receiving screen are sequentially arranged along the direction far away from an optical platform, the inner focusing telescope adjusts the marking center of the lamp chamber position calibration plate, the marking centers of the light source and the light receiving screen to the same reference optical axis, the light source is arranged at a theoretical first focus of the ellipsoid reflecting mirror, the marking center of the light receiving screen is arranged at a theoretical second focus, on the basis, the ellipsoid reflecting mirror is arranged, the light receiving screen, the light source, a five-dimensional adjusting mechanism and the ellipsoid reflecting mirror form a detection adjusting unit, the position of the ellipsoid reflecting mirror is adjusted through the five-dimensional adjusting mechanism, so that the light source is positioned at the actual first focus of the ellipsoid reflecting mirror, the mark center of the light receiving screen is arranged at the actual second focus, so that the optical axis of the ellipsoidal reflector is superposed with the reference optical axis, the relation between the optical axis of the ellipsoidal reflector and the position of the lamp chamber is established, the actual optical axis is confirmed, the positioning precision is improved, the integration precision of the exposure subsystem is improved, the emergent light spots of the light source can be adjusted only by adjusting the position of the ellipsoidal reflector after the positions of other components are calibrated, the adjusting process is simple, and the integration efficiency of the lamp chamber of the exposure subsystem is improved.

Optionally, as an implementation manner of the embodiment of the present invention, the embodiment details the step S110, as shown in fig. 4, fig. 4 is a schematic flow chart of another method for adjusting a position of an ellipsoidal reflector according to the embodiment of the present invention, specifically, a reference optical axis is formed by adjusting a mark center of a light source, a mark center of a lamp room position calibration plate, and a mark center of a light-receiving screen to be the same optical axis through an internal focusing telescope; and the light source is positioned at the theoretical first focus of the ellipsoidal reflector, and the mark center of the light-receiving screen is positioned at the second focus, and the method can comprise the following steps:

and step S210, focusing the inner focusing telescope to infinity, and providing a calibration light beam.

Before adjusting the position of lamp house position calibration version, light source calibration version and light-receiving screen in proper order, can also include: mounting the lamp house position calibration plate on a lamp house reference fixing plate; and placing the lamp chamber reference fixing plate on the optical platform, and adjusting the lamp chamber reference fixing plate through the lamp chamber position calibration plate.

Fig. 5 is a schematic structural diagram of another ellipsoidal reflector position adjustment apparatus according to an embodiment of the present invention, before step S210 is performed, a lamp chamber position calibration plate 17 may be installed on a lamp chamber reference fixing plate 19, a light source and a light source calibration plate 14 are related by an imager, a light source installation interface is reserved, and a light source 13 is installed. And a lamp house reference fixing plate 19 is placed on an optical platform 18, and a plane reflector 20, an internal focusing telescope 11 and a five-dimensional adjusting mechanism 16 can be sequentially installed to form the structure shown in fig. 5, namely, a position calibration unit.

On the basis of the structure shown in fig. 5, the inner focusing telescope 11 is focused to infinity, the lamp chamber position calibration plate 17, the light source calibration plate 14 and the light receiving screen 12 are sequentially subjected to position calibration, and external light sources are used for providing calibration light beams for all the markers, so that the calibration precision is improved. Optionally, in this embodiment, the light chamber position calibration board and the light source calibration board use a bright cross dividing board, and during calibration, the calibration light beam irradiates the plane where the marker is located, that is, the calibration surface. The light receiving screen adopts a dark cross-shaped dividing plate, and when the calibration is carried out, the calibration light beam irradiates from the back of the plane where the marker is located.

S220, sequentially adjusting the positions of the lamp room position calibration plate, the light source calibration plate and the light receiving screen; the light source is located at a theoretical first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is located at a second focus.

In the step, the light source can be adjusted to the theoretical first focus of the ellipsoidal reflector, the mark center of the light receiving screen is adjusted to the second focus, and then the lamp house position calibration board, the light source calibration board and the light receiving screen are subjected to position calibration through marks of all the components.

And step S230, adjusting the positions between each mark and the cross partition plate of the inner focusing telescope to meet the condition that Rx is smaller than a first angle threshold, Ry is smaller than a second angle threshold, Dx is smaller than a first distance threshold, and Dy is smaller than a second distance threshold.

The cross dividing plate forms a first coordinate system which takes the center of the cross as an origin, one scribing line as an abscissa axis and the other scribing line as an ordinate axis, and Rx is an included angle between a plane where the mark is located and the abscissa axis of the first coordinate system; ry is an included angle between the plane where the mark is located and the ordinate axis of the first coordinate system; dx is the offset of the orthographic projection of the mark center and the origin of the first coordinate system in the abscissa axis direction, and Dy is the offset of the orthographic projection of the mark center and the origin of the first coordinate system in the ordinate axis direction.

In the step, the positions of the lamp room position calibration plate, the light source calibration plate and the light receiving screen are sequentially adjusted according to the orthographic projection of each mark on the cross-shaped division plate in the inner focusing telescope, so that the mark center of the lamp room position calibration plate, the mark centers of the light source and the light receiving screen are all located on the reference optical axis, and the plane of the lamp room position calibration plate, the plane of the light source calibration plate and the plane of the light receiving screen are all perpendicular to the reference optical axis.

Specifically, as shown in fig. 6, fig. 6 is a schematic diagram of a mark alignment structure according to an embodiment of the present invention, the cross dividing plate 22 includes mutually perpendicular scribe lines, in this embodiment, the center of the cross dividing plate 22 is taken as an origin O1, one of the scribe lines is taken as an abscissa axis X, and the other scribe line is taken as an ordinate axis Y, so as to form a first coordinate system of a plane where the cross dividing plate is located. The alignment between the orthographic projection of the mark on the cross-shaped reticle 22 and the first coordinate system is performed. In the embodiment, a cross-shaped mark is taken as an example to illustrate, so as to facilitate the alignment of the optical axis, as shown in fig. 6, if the orthogonal projection of the mark center O1 on the cross-shaped partition plate 22 does not coincide with the origin O, it is indicated that the mark and the optical axis of the inner focusing telescope are offset, and it is necessary to control the component where the mark is located to move on the plane perpendicular to the optical axis of the inner focusing telescope, so that the orthogonal projection of the mark center O1 on the cross-shaped partition plate coincides with the origin O, specifically, the offset of the orthogonal projection of the mark center O1 and the origin O of the first coordinate system in the X direction of the abscissa axis is controlled to be smaller than a first distance threshold, and the offset of the orthogonal projection of the mark center O1 and the origin O of the first coordinate system in the Y direction of the ordinate axis is controlled to be smaller than a second distance threshold, so that the mark center O1 approaches the origin O infinitely, thereby making the mark center O of the lamp room position calibration plate, the mark center O, the mark center of the cross-shaped partition plate, the cross-shaped mark center of the cross-shaped mark and the cross-shaped mark center of the cross-shaped mark are controlled to coincide with the offset of the cross-shaped mark center of the offset in the X-shaped mark center of the offset in the X-shaped partition plate in the offset of the X-shaped mark center of the offset of the X-shaped partition plate in the X-shaped mark center of the offset of the origin O-shaped partition plate in the X-shaped partition plate in the origin O-shaped partition plate in the X-shaped partition plate, and the offset of, The marking centers of the light source and the light receiving screen are both positioned on the optical axis of the inner focusing telescope to form a reference optical axis. Illustratively, the first distance threshold is less than or equal to 10 μm and the second distance threshold is less than or equal to 10 μm.

In addition, an angle Rx between the plane of the controllable mark and the abscissa axis X of the first coordinate system is smaller than a first angle threshold, and an angle Ry between the plane of the controllable mark and the ordinate axis Y of the first coordinate system is smaller than a second angle threshold. The plane of the lamp chamber position calibration plate, the plane of the light source calibration plate and the plane of the light receiving screen are perpendicular to the reference optical axis, and the position calibration precision is improved. As shown in fig. 7, fig. 7 is a schematic diagram of another alignment structure of a mark according to an embodiment of the present invention, when an included angle exists between a plane where the mark is located and a plane where the first coordinate system is located, an orthogonal projection of the mark on the cross partition plate 22 forms an eccentric cross shape with an offset center, for example, fig. 7 shows the eccentric cross shape under the condition of an included angle Ry between the plane where the mark is located and a ordinate axis Y of the first coordinate system, and in this embodiment, the included angle between the plane where the mark is located and an abscissa axis and an ordinate axis of the first coordinate system can be adjusted. Illustratively, the first angular threshold may be less than or equal to 15 μ rad, and the second angular threshold may be less than or equal to 15 μ rad, such that the plane of the indicia is parallel to the cross-hatch 22.

And S240, locking the positions of the lamp room position calibration plate, the light source calibration plate and the light receiving screen, so that the mark centers of the light source and the lamp room position calibration plate and the mark center of the light receiving screen are adjusted to be the same optical axis, and a reference optical axis is formed.

When the values of the Rx, Ry, Dx and Dy parameters are controlled, the marking centers of the light source, the lamp chamber position calibration plate and the light receiving screen are adjusted to be the same optical axis to form a reference optical axis, and the plane of the lamp chamber position calibration plate, the plane of the light source calibration plate and the plane of the light receiving screen are perpendicular to the reference optical axis. And then the positions of the lamp chamber position calibration plate, the light source calibration plate and the light receiving screen can be locked, and the relation between the optical axis of the ellipsoid reflecting mirror and the position of the lamp chamber is established.

In a certain example, through above-mentioned position calibration scheme, can realize that lamp house position marks the position of version, light source mark version and photic screen and marks and adjust, actual measurement location structure: each mark Dx is 0.615 μm, Dy is 0.924 μm, Dz is 0.050 μm, Rx is 1.2 μ rad, and Ry is 1.1 μ rad, so that the position calibration error is small, and the accuracy of the position calibration is improved.

The light chamber position calibration plate, the light source calibration plate, the light receiving screen and the inner focusing telescope optical axis are aligned in sequence, so that the marking centers of the light source and the light receiving screen and the marking center of the light receiving screen form a reference optical axis, alignment between the actual optical axis of the ellipsoidal reflector and the reference optical axis is conveniently and subsequently performed, the adjusting precision of the ellipsoidal reflector is improved, and the adjusting process is simplified.

Optionally, as another implementation manner of the embodiment of the present invention, in this embodiment, the step S120 is described in detail, as shown in fig. 8, fig. 8 is a schematic flow chart of another method for adjusting a position of an ellipsoidal reflector according to the embodiment of the present invention, and specifically, the five-dimensional adjustment mechanism is further configured to adjust a position of the ellipsoidal reflector so that the light source is located at an actual first focus of the ellipsoidal reflector and the mark center of the light-receiving screen is located at an actual second focus of the ellipsoidal reflector, and the method may include the following steps:

step S310, installing an ellipsoidal reflector on the five-dimensional adjusting mechanism; starting a light source, and acquiring light source images on a light receiving screen; a second coordinate system taking the first direction as an abscissa axis and the second direction as an ordinate axis is formed in the plane of the light receiving screen; the first direction is vertical to the second direction; the origin of the second coordinate system is located on the reference optical axis.

Fig. 9 is a schematic structural diagram of another position adjustment device for an ellipsoidal reflector according to an embodiment of the present invention, and with respect to the position calibration unit shown in fig. 5, the ellipsoidal reflector position adjustment device in fig. 9 removes the inner focusing telescope 11 and installs the ellipsoidal reflector 15, so that the light receiving panel 12, the light source 13, the ellipsoidal reflector 15, and the five-dimensional adjustment mechanism 16 form a detection adjustment unit. The light source 13 is turned on so that the light source 13 forms a light source image 23 on the light receiving panel 12. Similarly, in the present embodiment, a second coordinate system with the first direction as the abscissa axis X 'and the second direction as the ordinate axis Y' is formed in the plane where the light receiving panel 12 is located; the first direction X 'is perpendicular to the second direction Y'. The intersection of the abscissa axis X ' and the ordinate axis Y ', i.e., the origin O ' of the second coordinate system, is located on the reference optical axis.

Step S320, moving the light source image to an origin covering the second coordinate system, and obtaining coordinates of an intersection of the light source image and the second coordinate system: a first position coordinate (X1, 0), a second position coordinate (-X2, 0), a third position coordinate (0, Y1), a fourth position coordinate (0, -Y2); x1, X2, Y1 and Y2 are positive numbers.

With continued reference to fig. 9, the position of the ellipsoidal reflector 15 is adjusted so that the light source image 23 moves to the origin O 'covering the second coordinate system, and the ellipsoidal reflector 15 is finely adjusted so that the light source image 23 forms a circular light spot whose center is located at the origin O', so that the actual optical axis of the ellipsoidal reflector 15 coincides with the reference optical axis, the actual first focus of the ellipsoidal reflector 15 coincides with the theoretical first focus, and the actual second focus coincides with the theoretical second focus. The intersection points of the outer contour of the light source image 23 and the abscissa axis X 'may be set as the first position coordinate (X1, 0) and the second position coordinate (-X2, 0), and the intersection points with the ordinate axis Y' may be set as the third position coordinate (0, Y1) and the fourth position coordinate (0, -Y2), where X1, X2, Y1, and Y2 are positive numbers, and-X2 and-Y2 are negative numbers.

Step S330, adjusting the position of the ellipsoidal reflector in a plane perpendicular to the reference optical axis to enable | X1-X2| < d1, | Y1-Y2| < d 2; d1 is the lateral offset threshold and d2 is the longitudinal offset threshold.

Referring to fig. 9, in order to avoid misalignment of the actual optical axis L2 of the ellipsoidal mirror with the reference optical axis L1 in a plane perpendicular to the reference optical axis, | X1-X2| may be controlled to be smaller than the lateral shift threshold d1, that is, X1 and X2 are approximately equal, so that the center of the light source image 23 approaches the origin O 'in the direction of the abscissa axis X', and | Y1-Y2| may be controlled to be smaller than the longitudinal shift threshold d2, that is, Y1 and Y2 are approximately equal, so that the center of the light source image 23 approaches the origin O 'in the direction of the ordinate axis Y'.

Step S340, adjusting the included angle between the ellipsoidal reflector and a plane perpendicular to the reference optical axis to enable | (X1-X2) - (Y1-Y2) | < d 3; d3 is the overall offset threshold.

Fig. 10 is a schematic structural diagram of a light source imaging according to an embodiment of the present invention, in which when there is a crossing misalignment between an actual optical axis of an ellipsoidal reflector and a reference optical axis, a light source image 23 is distorted, for example, a circular light source may form an elliptical light source image 23 on a light-receiving screen, in order to prevent the light source image 23 from being deformed and avoid the crossing misalignment between the actual optical axis L2 of the ellipsoidal reflector and the reference optical axis L1, in this embodiment | (X1-X2) - (Y1-Y2) | may be controlled to be smaller than a total deviation threshold d3, specifically, an angle between the ellipsoidal reflector and a plane perpendicular to the reference optical axis, that is, an angle between a focal plane of a first focus of the ellipsoidal reflector and a plane perpendicular to the reference optical axis, may be adjusted to achieve a purpose that the focal plane of the first focus of the ellipsoidal reflector tends to be perpendicular to the reference optical axis, therefore, the light source imaging is not easy to deform.

Step S350, by adjusting the position of the ellipsoidal mirror in a plane parallel to the reference optical axis such that d4< X1+ X2< d5, d6< Y1+ Y2< d 7; d4 is the first size threshold, d5 is the second size threshold, d6 is the third size threshold, and d7 is the fourth size threshold.

The purpose of this embodiment is to set the light receiving panel at the focal plane close to the second focal point of the ellipsoidal reflector, but when the light receiving panel is too close to or too far from the ellipsoidal reflector, the size of the light source image on the light receiving panel will become larger, and this embodiment can determine the standard size of the light source image at the focal plane of the second focal point according to the size of the light source, the magnification of the ellipsoidal reflector, and the like, and control d4< X1+ X2< d5 so that the size in the X 'direction of the imaging abscissa axis of the light source is within the range between the first size threshold d4 and the second size threshold d5, and the standard size in the X' direction of the imaging abscissa axis of the light source is between the first size threshold d4 and the second size threshold d 5. Similarly, d6< Y1+ Y2< d7 is controlled such that the dimension in the X 'direction of the light source imaging abscissa axis is in the range between the third size threshold d6 and the fourth size threshold d7, and the standard dimension in the Y' direction of the light source imaging ordinate axis is between the third size threshold d6 and the fourth size threshold d 7. Specifically, the present embodiment adjusts the distance between the ellipsoidal mirror and the light receiving screen by adjusting the position in a plane parallel to the reference optical axis.

In this embodiment, the standard size of the light source image can be obtained according to the following derivation process. As shown in fig. 11, fig. 11 is an optical path diagram of a light source imaging according to an embodiment of the present invention. The vertex of the ellipsoid reflecting mirror is used as an origin O ", the optical axis direction is used as an abscissa axis X", the direction perpendicular to the optical axis is used as an ordinate axis Y ", a third coordinate system is established, emergent rays AB sent by a light source reach the ellipsoid reflecting mirror and are reflected to form reflected rays BA2, a reflection point B (x.y) can be obtained according to an ellipsoid curve equation, an included angle between the emergent rays AB and the abscissa axis X" is U, tan U is Y/(L-X), L is AO ", BC is the length of a curved surface, BC is a normal line of the curved surface at the point B, an included angle between the normal line and the abscissa axis X" is Q, according to a reflection law: i' and Q-U-i + U1; therefore, when it is known that the angle between the outgoing light ray AB and the abscissa axis X "is U, and the angle between the reflected light ray BA2 and the abscissa axis X" is U1, the length of the axis intersection A2 between the reflected light ray BA2 and the abscissa axis X "is A2O" is obtained from the results of the calculation that tan U1 is y/(L '-X) and L' isx + y/tan U1; it is also known that, when tanU1 is h '/(L' -f2), h '═ L' -f 2/tanU 1 can be obtained. From the above formula, the intersection a1 of the reflected ray BA2 with the focal plane of the second focal point may be calculated, and the standard size of the light source image at the focal plane of the second focal point determined.

Optionally, the maximum size of the light source in this embodiment may be 1 mm; the light source at the second focus is imaged to 9.4mm, calculated from the magnification of the ellipsoidal mirror. Then d4 may be set to be greater than or equal to 9.3mm, d5 may be less than or equal to 9.5mm, d6 may be greater than or equal to 9.3mm, and d7 may be less than or equal to 9.5mm, such that the origin of the light-receiving screen is adjusted toward the actual second focal point, and the plane of the light-receiving screen is parallel to the focal plane of the actual second focal point.

Optionally, d1 is less than or equal to 0.1mm, d2 is less than or equal to 0.1mm, and d3 is less than or equal to 0.1mm, so that the actual optical axis and the reference optical axis are prevented from being displaced in parallel or crossed and dislocated.

In summary, the steps S330 to S350 can control the actual optical axis of the ellipsoidal reflector and the reference optical axis to tend to coincide, and can make the actual first focus of the ellipsoidal reflector coincide with the theoretical first focus, and the actual second focus coincides with the theoretical second focus, specifically, the method is implemented by performing five-dimensional position adjustment on the ellipsoidal reflector. It should be noted that the execution sequence of the above steps S330 to S350 is arbitrarily exchanged, and the execution sequence is not limited in this embodiment.

And S360, locking the position of the ellipsoidal reflector, wherein the light source is positioned at the actual first focus of the ellipsoidal reflector, and the mark center of the light receiving screen is positioned at the actual second focus of the ellipsoidal reflector.

In the embodiment, the position of the ellipsoidal reflector is adjusted in the five-dimensional direction by controlling the ellipsoidal reflector, so that the actual optical axis of the ellipsoidal reflector and the reference optical axis tend to coincide, the actual first focus of the ellipsoidal reflector coincides with the theoretical first focus, and the actual second focus coincides with the theoretical second focus, thereby improving the positioning precision of the ellipsoidal reflector and the uniformity of light source imaging.

In addition, in another implementation manner of the present embodiment, the reference optical axis establishing scheme of steps S210 to S240 and the detection and adjustment scheme of the ellipsoidal mirror of steps S330 to S350 may be adopted at the same time to implement the ellipsoidal mirror position adjustment method of the present embodiment.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.