| Projection optical system, exposure apparatus, and exposure method -> Monitor Keywords |
|
|
  Projection optical system, exposure apparatus, and exposure methodUSPTO Application #: 20070297072Title: Projection optical system, exposure apparatus, and exposure method Abstract: A projection objective includes at least four curved mirrors, which include a first curved mirror that is a most optically forward mirror and a second curved mirror that is a second most optically forward mirror, as defined along a light path. In addition, an intermediate lens element is disposed physically between the first and second mirrors, the intermediate lens element being a single pass type lens. The objective forms an image with a numerical aperture of at least substantially 1.0 in immersion. (end of abstract) Agent: Oliff & Berridge, PLC - Alexandria, VA, US Inventor: Yasuhiro Omura USPTO Applicaton #: 20070297072 - Class: 359730000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070297072. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a continuation of U.S. patent application Ser. No. 11/266,288 filed Nov. 4, 2005, which in turn is a continuation-in-part of International Application No. PCT/JP2004/006417 filed May 6, 2004. Application Ser. No. 11/266,288 also claims the benefit of U.S. Provisional Application No. 60/721,582 filed Sep. 29, 2005. The disclosures of these prior applications are incorporated herein by reference in their entirities. FIELD OF THE INVENTION [0002] The present invention relates to a catadioptric projection optical system, exposure apparatus, and exposure method and, more particularly, to a high-resolution catadioptric projection optical system suitable for exposure apparatus used in production of semiconductor devices, liquid-crystal display devices, etc. by photolithography. RELATED BACKGROUNDART [0003] The photolithography for production of the semiconductor devices and others is implemented using a projection exposure apparatus for projecting a pattern image of a mask (or a reticle) through a projection optical system onto a wafer (or a glass plate or the like) coated with a photoresist or the like. The resolving power (resolution) required for the projection optical system of the projection exposure apparatus is becoming increasingly higher and higher with increase in integration degree of the semiconductor devices and others. [0004] As a result, in order to satisfy the requirements for the resolving power of the projection optical system, it is necessary to shorten the wavelength .lamda. of illumination light (exposure light) and to increase the image-side numerical aperture NA of the projection optical system. Specifically, the resolution of the projection optical system is expressed by k.lamda./NA (where k is the process coefficient). The image-side numerical aperture NA is represented by nsin .theta., where n is a refractive index of a medium (normally, gas such as air) between the projection optical system and the image plane and .theta. a maximum angle of incidence to the image plane. [0005] In this case, if the maximum incidence angle .theta. is increased in order to increase the numerical aperture NA, it will result in increasing the input angle to the image plane and the output angle from the projection optical system, so as to increase reflection loss on optical surfaces and thus fail to secure a large effective image-side numerical aperture. For this reason, there is the known technology of increasing the numerical aperture NA by filling a medium like a liquid with a high refractive index in the optical path between the projection optical system and the image plane. [0006] However, application of this technology to the ordinary dioptric projection optical systems caused such disadvantages that it was difficult to well correct for chromatic aberration and to satisfy the Petzval's condition to well correct for curvature of field, and that an increase in the scale of the optical system was inevitable. In addition, there was another disadvantage that it was difficult to secure a large effective image-side numerical aperture while well suppressing the reflection loss on optical surfaces. SUMMARY OF THE INVENTION [0007] A first object of the embodiment is to provide a relatively compact projection optical system having excellent imaging performance as well corrected for various aberrations, such as chromatic aberration and curvature of field, and being capable of securing a large effective image-side numerical aperture while well suppressing the reflection loss on optical surfaces. [0008] In the case where the projection optical system is composed of only reflecting optical members and in the case where the projection optical system is composed of a combination of refracting optical members with reflecting optical members, with increase in the numerical aperture, it becomes more difficult to implement optical path separation between a beam entering a reflecting optical member and a beam reflected by the reflecting optical member and it is infeasible to avoid an increase in the scale of the reflecting optical member, i.e., an increase in the scale of the projection optical system. [0009] In order to achieve simplification of production and simplification of mutual adjustment of optical members, it is desirable to construct a catadioptric projection optical system of a single optical axis; in this case, with increase in the numerical aperture, it also becomes more difficult to achieve the optical path separation between the beam entering the reflecting optical member and the beam reflected by the reflecting optical member, and the projection optical system increases its scale. [0010] A second object of the embodiment is to achieve a large numerical aperture, without increase in the scale of optical members forming a catadioptric projection optical system. [0011] A third object of the embodiment is to provide an exposure apparatus and exposure method capable of performing an exposure to transcribe a fine pattern with high accuracy through a projection optical system having excellent imaging performance and having a large effective image-side numerical aperture and therefore a high resolution. In order to achieve the above-described first object, a projection optical system according to a first aspect of the embodiment is a catadioptric projection optical system for forming a reduced image of a first surface on a second surface, [0012] the projection optical system comprising at least two reflecting mirrors, and a boundary lens whose surface on the first surface side has a positive refracting power, [0013] wherein, where a refractive index of an atmosphere in an optical path of the projection optical system is 1, an optical path between the boundary lens and the second surface is filled with a medium having a refractive index larger than 1.1, [0014] wherein every transmitting member and every reflecting member with a refracting power constituting the projection optical system are arranged along a single optical axis, and [0015] the projection optical system having an effective imaging area of a predetermined shape not including the optical axis. [0016] In order to achieve the above-described second object, a projection optical system according to a second aspect of the embodiment is a catadioptric projection optical system for forming an image of a first surface on a second surface, the projection optical system comprising: [0017] a first imaging optical system comprising two mirrors, for forming an intermediate image of the first surface; and [0018] a second imaging optical system for forming the intermediate image on the second surface, [0019] wherein the second imaging optical system comprises the following components in order of passage of a ray from the intermediate image side: [0020] a first field mirror of a concave shape; Continue reading... Full patent description for Projection optical system, exposure apparatus, and exposure method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Projection optical system, exposure apparatus, and exposure method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Projection optical system, exposure apparatus, and exposure method or other areas of interest. ### Previous Patent Application: Optical imaging device for a camera Next Patent Application: 3d enhancement system for monitor Industry Class: Optical: systems and elements ### FreshPatents.com Support Thank you for viewing the Projection optical system, exposure apparatus, and exposure method patent info. IP-related news and info Results in 0.8801 seconds Other interesting Feshpatents.com categories: Computers: Graphics , I/O , Processors , Dyn. Storage , Static Storage , Printers |
||
