JP2006073905A - Optical system, adjustment method therefor, aligner, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system capable of highly precisely adjusting inclinations and positions in the axial direction of a plurality of optical elements that constitute an optical system, and to provide an adjustment method for the optical system, an aligner, and a device manufacturing method. <P>SOLUTION: The optical system comprises a plurality of optical elements, and has a drive means for driving the optical elements, and a planar Fizeau lens which is formed on at least one of the plurality of optical elements and serves as a reference for the inclinations and positions in the optical axis direction of the optical elements relative to the axis of the optical system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention generally relates to an exposure apparatus, and more particularly to a reticle pattern in an exposure apparatus used in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, an imaging element (CCD, etc.) or a thin film magnetic head. The present invention relates to a projection optical system that projects a projection onto a target object and a method for adjusting the projection optical system. The present invention is particularly suitable for an exposure apparatus that uses ultraviolet light or extreme ultraviolet (EUV) light as an exposure light source.

  When manufacturing a fine semiconductor element such as a semiconductor memory or a logic circuit using a photolithography technique, a circuit pattern drawn on a reticle (mask) is applied to a wafer coated with a photosensitive agent by a projection optical system. Conventionally, a reduction projection exposure apparatus that projects and transfers a circuit pattern has been used. The projection optical system used in the reduction projection exposure apparatus includes a refractive projection optical system composed of a refractive optical element (such as a lens) having optical characteristics that transmits exposure light, and reflective optics having optical characteristics that reflect exposure light. A reflection type projection optical system composed of elements (such as mirrors) and a catadioptric projection optical system combining a refractive optical element and a reflective optical element are known.

  The minimum dimension (resolution) that can be transferred by the reduction projection exposure apparatus is proportional to the wavelength of light used for exposure and inversely proportional to the numerical aperture (NA) of the projection optical system. Therefore, the shorter the wavelength, the better the resolution. For this reason, with the recent demand for miniaturization of semiconductor elements, the wavelength has been shortened, and an ultra-high pressure mercury lamp (i-line (wavelength: about 365 nm)), KrF excimer laser (wavelength: about 248 nm), ArF excimer laser (wavelength). The wavelength of ultraviolet light used is about 193 nm).

  However, semiconductor elements are rapidly miniaturized, and there is a limit in lithography using ultraviolet light. Therefore, in order to transfer a very fine circuit pattern of 0.1 μm or less, a reduction projection exposure apparatus (hereinafter, referred to as “extreme ultraviolet (EUV) light) having a wavelength shorter than that of ultraviolet light and having a wavelength of about 5 nm to 15 nm (hereinafter referred to as“ ultraviolet light ”). "EUV exposure apparatus") has been developed.

  In the EUV light wavelength range, the absorption of light by a substance becomes very large, so that a refractive optical element used for visible light or ultraviolet light is not practical (that is, there is no glass material that transmits EUV light). In a EUV exposure apparatus, a reflective projection optical system using a reflective optical element is used. For example, a projection optical system composed of four reflective optical elements has been proposed (see, for example, Patent Document 1).

  In the manufacture of the projection optical system of an exposure apparatus including an EUV exposure apparatus, in order to satisfy the required imaging performance of the projection optical system, the inclination of each optical element with respect to the optical axis and the optical elements in the optical axis direction It is necessary to adjust the interval of the high accuracy. Further, it is conceivable that the optical element is inclined and the position in the optical axis direction is shifted due to the transport of the exposure apparatus and a change with time, and the imaging performance of the projection optical system is deteriorated. When a deviation occurs in the inclination of the optical element and the position in the optical axis direction, it is necessary to adjust the inclination of each optical element with respect to the optical axis and the interval between the optical elements in the optical axis direction again.

  In the production of a conventional projection optical system, first, the projection optical system is assembled with mechanical accuracy using the reference frame attached to each optical element as a reference, and then an adjustment light source such as visible light or ultraviolet light is used. The imaging performance of the projection optical system is measured, and the inclination of each optical element with respect to the optical axis and the distance between the optical elements in the optical axis direction are adjusted based on the measurement result (coarse adjustment). Next, similarly, the imaging performance of the projection optical system is measured using the exposure light source, and the inclination of each optical element with respect to the optical axis and the distance between the optical elements in the optical axis direction are finely adjusted based on the measurement result. (Final adjustment).

In addition, a method using an interferometer has been proposed as a method for adjusting the projection optical system (see, for example, Patent Document 2).
JP 2000-98228 A JP 2003-35597 A

  However, when the wavelength of the exposure light source, such as an EUV exposure apparatus, becomes short, the wavelength of exposure light differs from that of visible light and ultraviolet light for adjustment, so chromatic aberration occurs in coarse adjustment using visible light and ultraviolet light. Resulting in. Chromatic aberration increases the adjustment error in rough adjustment, and thus causes a problem that a long time is required for final adjustment and that exposure light does not form an image in the final adjustment.

  In addition, when the optical element is tilted and the position in the optical axis direction is deviated due to transport of the exposure apparatus or a change with time, it is necessary to take out and adjust the projection optical system from the exposure apparatus, which is very difficult. There is also a problem.

  Therefore, the present invention provides an optical system capable of adjusting the inclination and optical axis direction positions of a plurality of optical elements constituting the optical system with high accuracy on the apparatus, an adjustment method for the optical system, an exposure apparatus, and a device. It is an exemplary object to provide a manufacturing method.

  In order to achieve the above object, an optical system according to one aspect of the present invention is an optical system including a plurality of optical elements, and includes a driving unit that drives the optical elements, and at least the plurality of optical elements. And a flat Fizeau lens that serves as a reference for the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction.

  An adjustment method according to another aspect of the present invention is an adjustment method of an optical system including a plurality of optical elements, and is formed in at least one of the plurality of optical elements, the step of irradiating the optical system with light. Formed on an optical element other than the optical element on which the planar Fizeau lens is formed and the reflected light from the planar Fizeau lens that serves as a reference for the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction. Forming interference fringes with reflected light from the reference plane, and adjusting the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction based on the interference fringes. It is characterized by having.

  An exposure apparatus according to still another aspect of the present invention is an exposure apparatus that exposes a reticle pattern onto an object to be processed, and has an optical system that is adjusted using the adjustment method described above.

  An exposure apparatus according to still another aspect of the present invention is an exposure apparatus that exposes a reticle pattern onto an object to be processed, and is formed with a planar Fizeau lens that serves as a reference for the inclination with respect to the optical axis and the position in the optical axis direction. A first optical element and a second optical element having a reference plane formed thereon, a projection optical system for projecting the pattern onto the object to be processed, the first optical element, and the second optical element. Drive means for driving an optical element, a Fizeau interferometer for detecting optical characteristics of the projection optical system as interference fringes between reflected light from the planar Fizeau lens and reflected light from the reference plane, and the Fizeau interferometer And a control unit for controlling the driving means based on the detection result.

  According to still another aspect of the present invention, there is provided a device manufacturing method comprising: exposing a target object using the above-described exposure apparatus; and developing the exposed target object.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the optical system which can adjust the inclination of the some optical element which comprises an optical system, and the position of an optical axis direction with high precision on an apparatus, the adjustment method of the said optical system, exposure apparatus, and device A manufacturing method can be provided.

  Hereinafter, an exposure apparatus and a projection optical system according to one aspect of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted. Here, FIG. 1 is a schematic sectional view showing the structure of the exposure apparatus 1 of the present invention.

  The exposure apparatus 1 of the present invention uses extreme ultraviolet light (EUV light) EL in a soft X-ray region (wavelength of about 5 nm to 15 nm) as exposure illumination light (exposure light), for example, a step-and-scan method. Or a projection exposure apparatus that exposes a circuit pattern formed on the reticle 20 to the object 40 by a step-and-repeat method. Such an exposure apparatus is suitable for a lithography process of sub-micron or quarter micron or less, and in the present embodiment, a step-and-scan type exposure apparatus (also referred to as “scanner”) will be described as an example. Here, the “step and scan method” means that the wafer is continuously scanned (scanned) with respect to the reticle to expose the reticle pattern onto the wafer, and the wafer is stepped after completion of one shot of exposure. The exposure method moves to the next exposure area. The “step-and-repeat method” is an exposure method in which the wafer is stepped and moved to the exposure area of the next shot for every batch exposure of the wafer.

  As shown in FIG. 1, the exposure apparatus 1 includes an illumination apparatus 10, a reticle stage 30 on which the reticle 20 is placed, a wafer stage 50 on which the object to be processed 40 is placed, a projection optical system 100, and a Fizeau interferometer. The unit 200 and the control unit 300 are included.

  Although not shown in FIG. 1, EUV light has a low transmittance to the atmosphere and generates contamination due to a reaction with a residual gas (polymer organic gas or the like) component. The entire optical system) is preferably in a vacuum atmosphere.

  Further, in the present embodiment, the exposure apparatus 1 uses a projection optical system 100 that projects the principal ray of the reflected light beam from the reticle 20 as a projection original plate onto the workpiece 40 substantially vertically. In the following description, the projection direction of the principal ray of the EUV light EL from the projection optical system 100 onto the object 40 is referred to as the optical axis direction of the projection optical system 100, and the optical axis direction is referred to as the Z-axis direction. 1 is defined as the Y-axis direction, and the direction perpendicular to the sheet surface is defined as the X-axis direction.

  The illumination device 10 is an illumination device that illuminates the reticle 20 with arc-shaped EUV light (for example, wavelength 13.4 nm) with respect to the arc-shaped field of the projection optical system 100, and includes an EUV light source unit 12 and an illumination optical system 14. And have.

  As the EUV light source unit 12, for example, a laser plasma light source is used. The laser plasma light source irradiates a target material in a vacuum vessel with a high-intensity pulsed laser to generate high-temperature plasma, and uses EUV light having a wavelength of, for example, about 13 nm. As the target material, a metal film, a gas jet, a droplet, or the like is used. In order to increase the average intensity of the emitted EUV light, the repetition frequency of the pulse laser should be high, and it is usually operated at a repetition frequency of several kHz.

  The illumination optical system 14 is an optical system that uniformly illuminates the reticle 20. The illumination optical system 14 is composed of, for example, a condenser mirror and an optical integrator. The collector mirror serves to collect EUV light emitted approximately isotropically from the laser plasma. The optical integrator has a role of uniformly illuminating the reticle 20 with a predetermined numerical aperture. Further, the illumination optical system 14 may be provided with an aperture for limiting the illumination area of the reticle 20 in an arc shape at a position conjugate with the reticle 20.

  The reticle 20 is a reflective reticle, on which a circuit pattern to be transferred is formed, and is supported and driven by the reticle stage 30. The diffracted light emitted from the reticle 20 is reflected by the projection optical system 100 and projected onto the workpiece 40. The reticle 20 and the workpiece 40 are arranged in an optically conjugate relationship. Since the exposure apparatus 1 is a scanner in the present embodiment, the pattern of the reticle 20 is reduced and projected onto the object 40 by scanning the reticle 20 and the object 40.

  The reticle stage 30 supports the reticle 20 via a reticle chuck, for example, and is connected to a moving mechanism (not shown). The reticle stage 30 can employ any structure known in the art. A moving mechanism (not shown) is configured by a linear motor or the like, and can move the reticle 20 by driving the reticle stage 30 at least in the X-axis direction. The exposure apparatus 1 scans the reticle 20 and the workpiece 40 in a synchronized state.

  The object to be processed 40 is a wafer in this embodiment, but widely includes a liquid crystal substrate and other objects to be processed. A photoresist is applied to the object to be processed 40.

  The wafer stage 50 supports the workpiece 40 via a wafer chuck. The wafer stage 50 moves the workpiece 40 in the X-axis, Y-axis, and Z-axis directions using, for example, a linear motor. The position of the reticle stage 30 and the position of the wafer stage 50 are monitored by, for example, a laser interferometer, and both are driven at a constant speed ratio.

  The projection optical system 100 is composed of a plurality of optical elements, and reduces and projects the pattern of the reticle 20 onto the object to be processed 40. In the present embodiment, the projection optical system 100 includes four reflective optical elements, ie, a first mirror 110, a second mirror 120, a third mirror 130, and a fourth mirror 140. In order to realize a wide exposure area with a small number of mirrors, the reticle 20 and the object to be processed 40 are simultaneously scanned using only a thin arc-shaped area (ring field) separated from the optical axis by a certain distance. Transfer the area.

  The reflecting surfaces (surfaces) of the first mirror 110 to the fourth mirror 140 are processed with an accuracy of about 1/50 to 1/60 or less of the exposure wavelength with respect to the design value. The first mirror 110 to the fourth mirror 140 are made of a low thermal expansion glass material, ceramics or metal, and a reflective film for reflecting the EUV light EL is formed on the surface. Such a reflective film has a function of strengthening light and is formed of a multilayer film in which two kinds of substances having different optical constants are alternately stacked. As a multilayer film capable of reflecting EUV light having a wavelength of 20 nm or less, for example, a Mo / Si multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately stacked is considered. On the other hand, a reflectance of 70% can be obtained. However, the multilayer film is not limited to the above-described materials, and a multilayer film having the same operation and effect as this can be applied.

  The first mirror 110 to the fourth mirror 140 are connected to the projection optical system 100 via drive elements 112 to 142. The drive elements 112 to 142 are composed of, for example, piezoelectric elements (piezo elements) and have a function of driving the first mirror 110 to the fourth mirror 140. Specifically, the drive elements 112 to 142 can change the inclination of the first mirror 110 to the fourth mirror 140 with respect to the optical axis and the position in the optical axis direction.

  Of the plurality of optical elements constituting the projection optical system 100, the optical element disposed at the uppermost end (that is, the most reticle side) or the optical element disposed at the lowermost end (that is, the most object side) is: A flat Fizeau lens 160 is formed as a reference for the tilt with respect to the optical axis and the position in the optical axis direction. Thus, as will be described later, the projection optical system 100 can be adjusted by performing measurement with a Fizeau interferometer from one direction (that is, the reticle side or the object to be processed).

  In the present embodiment, a planar Fizeau lens outside the effective reflection surface of the third mirror 130 disposed at the lowermost end of the first mirror 110 to the fourth mirror 140 (that is, the region not irradiated with the EUV light EL). 160 is formed.

  In the planar Fizeau lens 160, a surface (back surface) 160b facing the Fizeau surface 160a is formed to be inclined with respect to the Fizeau surface 160a. Thereby, the reflected light from the back surface 160b can be prevented from returning to the Fizeau interference unit 200 described later.

  A reference plane 114 perpendicular to the optical axis is formed on the surface (back surface) 110b of the first mirror 110 facing the reflective surface 110a. In the second mirror 120 and the fourth mirror 140, reference planes 124 and 144 perpendicular to the optical axis are provided outside the effective reflection surface (that is, the reflection surfaces 120a and 140b in the region where the EUV light EL is not irradiated). Each is formed.

  In the present embodiment, the measurement light beam ML transmitted through the flat Fizeau lens 160 reaches the reference planes 114, 124, and 144 of the first mirror 110, the second mirror 120, and the fourth mirror 140. The first mirror 110 and the second mirror 120 are formed with through holes 116 and 126 for allowing the measurement light beam ML to pass therethrough. If the reference planes overlap, the positions are shifted.

  As for the reference plane 114 of the first mirror 110, there is nothing to block the measurement light beam ML between the flat Fizeau lens 160 and the reference plane 114, so that the measurement light beam ML transmitted through the flat Fizeau lens 160 is directly applied to the reference plane 114. The light beam projected and reflected by the reference plane 114 returns to the interferometer unit 200.

  With respect to the reference plane 124 of the second mirror 120, as shown in FIG. 2, a through hole 116 is formed in the first optical element 110, and the measurement light beam ML passes through the through hole 116, and the second optical element 110 The light beam projected on the reference plane 124 of the mirror 120 and reflected by the reference plane 124 returns to the interferometer unit 200. Here, FIG. 2 is a schematic plan view showing an example of the arrangement of the reference plane 114 and the through hole 116 of the first mirror 110 and the reference plane 124 and the through hole 126 of the second mirror 120.

  With respect to the reference plane 144 of the fourth mirror 140, as shown in FIG. 3, the measurement light beam ML passes through the through-hole 116 of the first mirror 110, and further, as shown in FIG. , The light beam projected onto the reference plane 144 of the fourth mirror 140 and reflected by the reference plane 144 returns to the interferometer unit 200. Here, FIG. 3 is a schematic plan view showing an example of the arrangement of the reference plane 114 and the through hole 116 of the first mirror 110 and the reference plane 144 of the fourth mirror 140. FIG. 4 is a schematic plan view illustrating an example of the arrangement of the reference plane 124 and the through hole 126 of the second mirror 120 and the reference plane 144 of the fourth mirror 140.

  The Fizeau interferometer unit 200 is disposed below the projection optical system 100, and reflects the optical characteristics of the projection optical system 100 by reflecting light from the planar Fizeau lens 160 formed on the third mirror 130 and the first mirror 110. Detection is performed as interference fringes with reflected light from the reference planes 114, 124, and 144 formed on the second mirror 120 and the fourth mirror 140.

  The measurement light beam ML emitted from the Fizeau interferometer unit 200 is incident on the planar Fizeau lens 160. A part of the measurement light beam ML incident on the flat Fizeau lens 160 is reflected by the Fizeau surface 160a as a reference wavefront and returns to the Fizeau interferometer unit 200. On the other hand, the remaining measurement light beam ML is transmitted as a plane light wave and reflected by the reference surfaces 114, 124, and 144 of the first mirror 110, the second mirror 120, and the fourth mirror 140, and Fizeau interferometers are used as measurement wavefronts. Return to unit 200.

  As shown in FIG. 2, the Fizeau interferometer unit 200 includes a wavelength modulation laser light source 210, a lens 220, a half mirror 230, a condenser lens 240, and a CCD camera 250. Note that the wavelength modulation laser light source 210 can change the wavelength of the measurement light beam ML by selectively switching, for example, two laser light sources having different wavelengths. Thereby, as will be described later, it is not necessary to scan the optical elements constituting the projection optical system 100 (in this embodiment, the first mirror 110 to the fourth mirror 140), and measurement is performed in a more stable state. Can do. In addition, by using two laser light sources having different wavelengths, the position of the optical element relative to the planar Fizeau lens can be detected by a synthetic wavelength method that determines the fringe order from the phase difference of each interference fringe caused by laser beams having different wavelengths. It becomes possible. Here, FIG. 2 is a schematic cross-sectional view showing an internal configuration of the Fizeau interference unit 200.

  The control unit 300 includes a CPU and a memory (not shown) and controls the operation of the exposure apparatus 1. The control unit 300 includes the illumination device 10, the reticle stage 30 (that is, a moving mechanism (not shown) of the reticle stage 30), the wafer stage 50 (that is, a moving mechanism (not shown) of the wafer stage 50), driving elements 112 to 142, and a Fizeau interferometer. The unit 200 is electrically connected. The CPU includes any processor of any name such as MPU and controls the operation of each unit. The memory is composed of ROM and RAM, and stores firmware that operates the exposure apparatus 1.

  In the present embodiment, the control unit 300 controls the drive elements 112 to 142 based on the detection result of the Fizeau interferometer unit 200. Specifically, the control unit 300 adjusts the inclination of the first mirror 110 to the fourth mirror 140 with respect to the optical axis and the position in the optical axis direction via the drive elements 112 to 142.

  Here, the control of the control unit 300 (that is, the adjustment method of the projection optical system 100) will be described together with the operation of the Fizeau interferometer unit 200.

  Laser light generated from the wavelength-modulated laser light source 210 is diverged by the lens 220, reflected by the half mirror 230, and emitted from the Fizeau interferometer unit 200 as a measurement light beam ML. A part of the measurement light beam ML emitted from the Fizeau interferometer unit 200 is reflected as a reference wavefront by the flat Fizeau lens 160 formed on the third mirror 130, and returns to the Fizeau interferometer unit 200. On the other hand, the remaining measurement light beam ML is transmitted through the planar Fizeau lens 160 and is incident on the reference planes 114, 124, and 144 of the first mirror 110, the second mirror 120, and the fourth mirror 140 constituting the projection optical system 100. Irradiated and reflected, each returns to the Fizeau interferometer unit 200 as a measurement wavefront. The reference wavefront and measurement wavefront that have returned to the Fizeau interferometer unit 200 are transmitted through the half mirror 230 and interfere on the imaging surface of the CCD camera 250 to form interference fringes.

  Next, the wavelength is varied by the wavelength modulation laser light source 210, and the phase distribution of the interference fringes is detected with high accuracy. From the phase distribution, the inclinations of the reference planes 114, 124, and 144 with respect to the planar Fizeau lens 160 can be measured. Based on the tilt information of the reference planes 114, 124, and 144 with respect to the planar Fizeau lens 160, the tilts of the first mirror 110, the second mirror 120, and the fourth mirror 140 are slightly moved by the drive elements 112, 122, and 142. Thus, the inclination of the reference planes 114, 124, and 144 with respect to the planar Fizeau lens 160 can be adjusted. In other words, the tilts of the first mirror 110, the second mirror 120, and the fourth mirror 140 are adjusted with respect to the third mirror 130.

  Next, the wavelength is switched by the wavelength modulation laser light source 210. Similarly, the reference planes 114, 124, and 144 formed on the first mirror 110, the second mirror 120, and the fourth mirror 140 with respect to the planar Fizeau lens 160 are changed. Each phase is detected. With respect to the reference planes 114, 124, and 144, the phase difference between the interference fringes by two lasers having different wavelengths is obtained, so that the positions of the reference planes 114, 124, and 144 in the optical axis direction with respect to the plane Fizeau lens 160 are determined by the synthetic wavelength method. Each can be measured. Note that the phase of the interference fringes can also be calculated by scanning the planar Fizeau lens 160 or the reference planes 114, 124, and 144 in the optical axis direction. However, as in this embodiment, it is preferable to calculate the phase of the interference fringes while changing the wavelength by the wavelength modulation laser light source 210 and keeping the optical element to be adjusted stationary (that is, in a stable state). Based on the information of the position of the first mirror 110, the second mirror 120, and the fourth mirror 140 in the optical axis direction from the planar Fizeau lens 160, the first mirror 110, the second mirror 120, and the fourth mirror The mirror 140 is finely moved in the optical axis direction by the drive elements 112, 122, and 142, so that the first mirror 110, the second mirror 120, and the fourth mirror 140 in the optical axis direction are referenced with the planar Fizeau lens 160 as a reference. The position can be adjusted.

  As described above, according to the exposure apparatus 1 and the projection optical system 100, when adjusting the projection optical system 100, the light from the first mirror 110 to the fourth mirror 140 can be easily and highly accurately. The inclination with respect to the axis and the position in the optical axis direction can be measured, and adjustment can be performed. Also, not only when the projection optical system 100 is assembled, but also when the tilt of the first mirror 110 and the fourth mirror 140 with respect to the optical axis and the position in the optical axis direction are shifted due to the conveyance of the apparatus and changes over time, It is possible to return the first mirror 1110 to the fourth mirror 140 to a predetermined position on the apparatus.

  In the exposure, the EUV light EL emitted from the illumination device 10 is reflected by the folding mirror RM, illuminates the reticle 20, and forms a pattern on the surface of the reticle 20 on the workpiece 40 by the projection optical system 100. . In this embodiment, the image plane is an arc-shaped (ring-shaped) image plane, and the reticle 20 and the workpiece 40 are scanned relative to the projection optical system 100 in a one-dimensional direction (Y-axis direction in the present embodiment). By doing so, the entire surface of the reticle 20 is exposed. The projection optical system 100 used by the exposure apparatus 1 exhibits desired imaging performance because the tilt of the optical elements constituting the projection optical system 100 and the position in the optical axis direction are adjusted with high accuracy. In addition, it is possible to provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin film magnetic head, etc.) with high throughput and high economic efficiency. Further, even when the tilt of the optical element with respect to the optical axis and the position in the optical axis direction shift due to changes over time, the adjustment can be performed on the apparatus without taking out the projection optical system 100, so that a decrease in throughput is minimized. Can be suppressed.

  Next, an embodiment of a device manufacturing method using the above-described exposure apparatus 1 will be described with reference to FIGS. FIG. 6 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

  FIG. 7 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus 1 to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to this device manufacturing method, it is possible to manufacture a higher quality device than before. Thus, the device manufacturing method using the exposure apparatus 1 and the resulting device also constitute one aspect of the present invention.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist. For example, the present invention can be applied not only to a projection optical system but also to adjustment of an illumination optical system. Further, the number of optical elements constituting the optical system is not limited to four, but may be four or less, or four or more.

It is a schematic sectional drawing which shows the structure of the exposure apparatus as one side surface of this invention. It is a schematic plan view which shows an example of arrangement | positioning with the reference plane and through-hole of a 1st mirror shown in FIG. 1, and the reference plane and through-hole of a 2nd mirror. It is a schematic plan view which shows an example of arrangement | positioning with the reference plane and through-hole of a 1st mirror shown in FIG. 1, and the reference plane of a 4th mirror. It is a schematic plan view which shows an example of arrangement | positioning with the reference plane and through-hole of a 2nd mirror shown in FIG. 1, and the reference plane of a 4th mirror. It is a schematic sectional drawing which shows the structure inside the Fizeau interference unit shown in FIG. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 7 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 100 Projection optical system 110 1st mirror 112 Driving element 114 Reference plane 116 Through-hole 120 Second mirror 122 Driving element 124 Reference plane 126 Through-hole 130 Third mirror 132 Driving element 140 Fourth mirror 142 Driving Element 144 Reference plane 160 Plane Fizeau lens 160a Fizeau surface 160b Back surface 200 Fizeau interferometer unit 210 Wavelength modulation laser light source

Claims (12)

An optical system composed of a plurality of optical elements,
Driving means for driving the optical element;
An optical system comprising at least one of the plurality of optical elements, and a planar Fizeau lens serving as a reference for the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction.   The optical system according to claim 1, wherein the planar Fizeau lens is formed on the optical element disposed at the uppermost end of the optical system or the optical element disposed at the lowermost end of the optical system.   The optical system according to claim 1, wherein the plurality of optical elements have through-holes through which light passes.   The optical system according to claim 1, wherein the plurality of optical elements are reflective optical elements. An optical system adjustment method comprising a plurality of optical elements,
Irradiating the optical system with light;
Reflected light from a planar Fizeau lens, which is formed in at least one of the plurality of optical elements and serves as a reference for the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction, and the planar Fizeau lens is formed Forming interference fringes with reflected light from a reference plane formed on an optical element other than the optical element formed;
Adjusting the inclination of the optical element with respect to the optical axis of the optical system and the position in the optical axis direction based on the interference fringes. The irradiation step includes
Irradiating the optical system with light having a first wavelength;
Irradiating the optical system with light having a second wavelength different from the first wavelength,
6. The adjustment method according to claim 5, further comprising a step of detecting a phase difference between an interference fringe due to the light of the first wavelength and an interference fringe due to the light of the second wavelength. An exposure apparatus that exposes a reticle pattern onto an object to be processed,
An exposure apparatus comprising an optical system adjusted using the adjustment method according to claim 5. An exposure apparatus that exposes a reticle pattern onto an object to be processed,
A first optical element on which a flat Fizeau lens serving as a reference for an inclination with respect to the optical axis and a position in the optical axis direction is formed; and a second optical element on which a reference plane is formed, and A projection optical system for projecting onto the processing body;
Driving means for driving the first optical element and the second optical element;
A Fizeau interferometer that detects optical characteristics of the projection optical system as interference fringes between reflected light from the planar Fizeau lens and reflected light from the reference plane;
An exposure apparatus comprising: a control unit that controls the driving unit based on a detection result of the Fizeau interferometer.   9. The exposure apparatus according to claim 8, wherein the first optical element is disposed closest to the reticle or closest to the object to be processed.   9. The exposure apparatus according to claim 8, wherein the Fizeau interferometer includes a wavelength modulation light source capable of changing a wavelength of light applied to the projection optical system.   The exposure apparatus according to claim 10, wherein the second optical element has a through hole through which the light passes. Exposing the object to be processed using the exposure apparatus according to any one of claims 7 to 11,
And developing the exposed object to be processed.