JP2011198990A - Method for measuring stray light of projection aligner, method for exposing projection aligner, and method for maintaining projection aligner - Google Patents

Abstract

In an exposure process, an optical system is gradually contaminated and fogging occurs. Due to this fogging, ultraviolet light used for exposure is scattered, and stray light is generated. When this stray light enters the photoresist, an area where the stray light is incident is exposed so as to overlap the reticle pattern, which makes it difficult to accurately transfer the reticle pattern to the photoresist.
Light is irradiated to a reticle blind 107 to obtain a light beam that has passed through an opening of the reticle blind 107. Then, the stage 110 is focused and an image including a shape similar to the opening is obtained. Then, the intensity distribution of the light beam is measured in a wider range than the image area similar to the opening. Then, when the light intensity of the image area and the light intensity of the area outside the image area are equal to or higher than a predetermined ratio, a maintenance operation is performed, so that the pattern of the reticle 10 is applied to the photoresist 11. Enables accurate transfer.
[Selection] Figure 4

Description

  The present invention relates to a measurement method for measuring stray light of a projection exposure apparatus, an exposure method for a projection exposure apparatus, and a maintenance method for a projection exposure apparatus.

  In forming a semiconductor element, a process of forming a pattern by applying a photoresist on a wafer, drying it, and then exposing it is widely used. Here, a projection exposure apparatus is widely used as an apparatus for exposing a photoresist.

  Among projection exposure apparatuses, a reduction exposure apparatus that performs exposure by reducing the size of a reticle (optical mask) to about 1/5 has been used in recent years. By using the reduction exposure apparatus, it is possible to reduce the influence of dust and the like adhering to the reticle (since the image is reduced by the reduction ratio, the influence of the dust is effectively 1 in this case. / 5).

  When exposure is performed using a reduction exposure apparatus, diffraction can be suppressed and a finer pattern can be formed by using short-wavelength ultraviolet light. For this reason, for example, ultraviolet light typified by i-line (wavelength 365 nm) of a mercury lamp or KrF excimer laser (wavelength 248 nm) is suitably used as a light source for exposure.

  In order to accurately transfer the reticle pattern to the photoresist, it is an important issue to suppress generation of stray light in the optical system provided in the reduction exposure apparatus between the light source and the wafer. The stray light means undesirable light caused by causes other than normal reflection and refraction, and is generated by scattering due to dirt or scratches on the lens, for example.

  In the exposure process, substances decomposed by ultraviolet rays adhere to the optical system, and the optical system is gradually contaminated and fogging occurs. Due to this fogging, ultraviolet light used for exposure is scattered, and stray light is generated. When the photoresist is exposed, if stray light enters, a portion that is not originally exposed is exposed, so that it is difficult to accurately transfer the reticle pattern to the photoresist.

  Therefore, as shown in Patent Document 1, after a photoresist is applied to a dummy wafer and dried, exposure is performed while changing the exposure amount for each shot using a reticle having a light shielding layer, and development is performed. There is known a method of measuring the amount of stray light by measuring a change in pattern shape caused by stray light using a pattern measuring device. It is described that by using this method, the occurrence of defects can be suppressed by cleaning the optical system while the amount of stray light is such that it does not cause transfer defects.

JP 2009-27196 A

However, when the amount of stray light is measured using the above-described method, a dedicated reticle is required, which raises a problem that inspection costs increase. Further, there is a problem that it takes time for inspection because a monitor wafer, an exposure / development process are required, and the pattern width is measured using a pattern measuring device. In addition, there are several factors that cause the pattern width to fluctuate, such as variations in photoresist thickness, fluctuations in development conditions, errors in the pattern measurement device, etc., so it is difficult to measure the amount of stray light purely. There are challenges. For this reason, when the above method is used, it is difficult to quantify the amount of stray light, and there is a problem that it is unclear at which point cleaning or component replacement should be performed.
In addition, since pattern exposure is performed, there is a problem that the amount of stray light is underestimated when stray light is generated in an optical axis range that overlaps the pattern (region that blocks light).

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
The light intensity in the following description means, for example, illuminance (unit area, light energy per unit time), and the unit is J / sec / cm ² . The product of illuminance and exposure time is the amount of light (exposure amount), and the unit is J / cm ² . Therefore, the illuminance and the light quantity can be converted by the same measurement method if the exposure time is known. That is, measuring the illuminance (light intensity) and measuring the amount of light mean the same thing.

  [Application Example 1] A measurement method according to this application example is a measurement method for measuring stray light of a projection exposure apparatus, and the projection exposure apparatus includes a light source and a shielding object having an opening for receiving light from the light source. And a stage for projecting the light beam focused by the lens as an image including a shape similar to the opening, and a stage for projecting the light beam obtained by passing through the opening. An apparatus comprising: projecting light emitted from the light source onto the stage as the image; and measuring the intensity distribution of the luminous flux in a wider range than the image area. To do.

  According to this, it becomes possible to detect the light intensity outside the image. In principle, no light beam exists outside the image, but stray light is generated due to contamination of the optical system between the light source and the stage, and this stray light is detected. Therefore, it is possible to directly measure the change in stray light due to contamination attached to the optical path of the optical system. Further, since the light on the entire surface of the opening is passed, stray light on the entire surface of the opening can be captured.

  This eliminates the need for a dedicated reticle, a monitoring wafer, and its exposure / development / pattern measurement, thereby shortening the time required for measurement and reducing costs. In addition, since there are no multiple factors such as uneven thickness of the photoresist, fluctuations in development conditions, and errors in the pattern measuring apparatus, it is possible to measure only the intensity of stray light. Further, since pattern exposure is not performed, stray light is generated in an optical axis range overlapping with a pattern (a region that blocks light), and the amount of stray light is not underestimated.

  Application Example 2 A measurement method for measuring stray light of the projection exposure apparatus according to the application example, wherein the size of the opening is changeable, and the intensity of the light beam is in a state where the opening is opened to the maximum size. Is measured.

  According to the measurement method described above, stray light in a state where the aperture is opened to the maximum dimension can be measured. Therefore, it is possible to grasp the stray light intensity in the widest range.

  Application Example 3 A measurement method for measuring stray light of the projection exposure apparatus according to the application example described above, wherein the intensity of the light beam is measured by moving one light sensor in and out of the image to measure the intensity distribution of the light beam. It is characterized by that.

  According to the measurement method described above, since the measurement is performed using the same light quantity sensor, the light intensity is measured relatively accurately without being affected by variations between the light quantity sensors as compared with the case where a plurality of light quantity sensors are used. It becomes possible.

  Application Example 4 An exposure method according to this application example is an exposure method of a projection exposure apparatus, and the projection exposure apparatus includes a light source, a shielding object having an opening that receives light from the light source, and the opening. A projection exposure apparatus comprising: a lens that focuses a light beam obtained by passing through a section; and a stage that projects the light beam focused by the lens as an image including a shape similar to the opening. A step of projecting light emitted from the light source onto the stage as the image, and a ratio of the light intensity of the area outside the image area to the light intensity of the image area is predetermined. When the value is less than the value, exposure is performed using a reticle having a transfer area that is equal to or smaller than the range irradiated with the light flux.

  According to this, since the opening includes an area corresponding to the transfer area of the reticle, the stray light intensity in the transfer area of the reticle can be measured. Therefore, the exposure process can be performed after grasping the stray light intensity.

  Application Example 5 In the exposure method of the projection exposure apparatus according to the application example, the predetermined ratio is 10% when the i-line of a mercury lamp is used as a light source, and a KrF excimer laser is used. In some cases, it is 1%.

  According to the exposure method described above, since a defect due to stray light occurs empirically when this proportion of stray light is generated, if the stray light is less than this proportion, a defect caused by stray light can be prevented in advance. It becomes possible to perform exposure.

  Application Example 6 A maintenance method according to this application example is a maintenance method for a projection exposure apparatus, and the projection exposure apparatus includes a light source, a shielding object having an opening for receiving light from the light source, and the opening. A projection exposure apparatus comprising: a lens that focuses a light beam obtained by passing through a section; and a stage that projects the light beam focused by the lens as an image including a shape similar to the opening. A step of projecting light emitted from the light source onto the stage as the image, and a ratio of the light intensity of the area outside the image area to the light intensity of the image area is predetermined. It is characterized in that maintenance work is performed when the value is greater than or equal to the value.

  According to this, it is possible to prevent defects caused by stray light by performing maintenance work when stray light of a predetermined ratio or more is detected by measurement.

  Application Example 7 In the maintenance method according to the application example, the predetermined ratio is 10% when the i-line of the mercury lamp is used as a light source, and 1 when the KrF excimer laser is used. %.

  According to the maintenance method described above, if this ratio of stray light occurs empirically, a defect due to stray light has occurred. Therefore, if this ratio of stray light occurs, maintenance is performed and stray light is generated. It is possible to prevent defects that occur.

  Application Example 8 A maintenance method according to the application example described above, wherein the maintenance method includes a step of cleaning with water, cleaning with ethanol, and drying.

  According to the maintenance method described above, maintenance can be performed without using a substance harmful to the human body. Moreover, it becomes possible to dry by suppressing generation | occurrence | production of a watermark etc. by cleaning and drying using ethanol.

1 is a schematic diagram of an exposure apparatus according to the present embodiment. FIG. 6 is a schematic perspective view for explaining the position of the reticle blind with respect to the reticle. The top view which shows the state which replaced with the board | substrate and mounted the light quantity sensor on the stage. The flowchart which shows the measurement and procedure of a stray light. (A), (b) is a relative luminous intensity map which shows relative light intensity distribution.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. FIG. 1 is a schematic view of an exposure apparatus according to this embodiment.

  The exposure apparatus 1 shown in FIG. 1 includes a mercury lamp 101, an elliptical mirror 102, a shutter 103, a reflecting mirror 104, an interference filter 105, a fly-eye lens 106, a reticle blind 107 as a shield, a reflecting mirror 108, a condenser lens 109, A projection optical unit PL and a stage 110 as an imaging surface are provided. Here, in addition to the components of the exposure apparatus 1, the drawing also shows a reticle 10, a photoresist 11, a wafer 12, and a substrate W that is a combination of the photoresist 11 and the wafer 12.

  Here, the elliptical mirror 102, the shutter 103, the reflecting mirror 104, the interference filter 105, the fly-eye lens 106, the reflecting mirror 108, the condenser lens 109, and the projection optical unit PL are hereinafter referred to as an optical system.

  The exposure apparatus 1 mounts a mask (hereinafter referred to as a reticle) 10 on which a mask pattern is formed between the condenser lens 109 and the projection optical unit PL, and reduces the mask pattern of the reticle 10 (for example, 1 / 5) Transfer to a wafer 12 coated with a photoresist 11 (hereinafter collectively referred to as a substrate W).

  Here, the mercury lamp 101 functions as a light source for exposure, and emits bright lines such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm). The elliptical mirror 102 improves the light density by converging light emitted from the mercury lamp 101 disposed in the vicinity of the focal point of the elliptical mirror 102 in one direction. Here, a combination of the mercury lamp 101 and the elliptical mirror 102 functions as a light source.

  The shutter 103 has a function of controlling the integrated light amount supplied to the substrate W and shielding light while the stage 110 described later is moving. The reflecting mirror 104 contributes to downsizing of the exposure apparatus 1 by changing the optical axis to accommodate the optical system. The interference filter 105 has a function of selectively transmitting, for example, i-line (wavelength 365 nm). The interference filter 105 can be omitted when a KrF excimer laser (wavelength 248 nm) having high monochromaticity is used instead of the mercury lamp 101. Further, since the emission directions of the laser beams are uniform, the elliptical mirror 102 can be omitted in this case. The fly-eye lens 106 has a function of making the illuminance distribution of the light transmitted through the interference filter 105 uniform together with the condenser lens 109.

  The reticle blind 107 is configured such that the diameter of the opening can be varied, and the light beam passing through the reticle blind 107 is narrowed by controlling the diameter of the opening. Therefore, the reticle 10 is irradiated with a light beam narrowed by the reticle blind 107. By providing the light beam with the light narrowed down in this way, the light beam passes only through a necessary portion of the reticle 10.

  Like the reflecting mirror 104, the reflecting mirror 108 contributes to downsizing of the exposure apparatus 1 by accommodating the optical system by changing the optical axis. The condenser lens 109 has a function of making the illuminance distribution of the light transmitted through the interference filter 105 uniform in combination with the fly-eye lens 106 described above. The projection optical unit PL projects the pattern of the reticle 10 arranged on the object plane onto the substrate W arranged on the image plane. The projection magnification of the projection optical unit PL is set to 1 / N. In the present embodiment, the projection optical unit PL is a reduction system having a projection magnification of 1/5. Note that the projection optical unit PL may be either an equal magnification system or an enlargement system. In addition, the projection optical unit PL has an imaging characteristic control device (not shown) that corrects the optical characteristics. Using this imaging characteristic control device, the projection magnification and aberration (field curvature) of the projection optical unit PL are corrected. Optical characteristics such as distortion, etc.) are adjusted.

  The stage 110 includes a driving mechanism (for example, a linear motor) (not shown), moves the substrate W in a direction intersecting with the optical axis of light to be exposed (in this embodiment, the case where the substrate W is orthogonal), and is drawn on the reticle 10. The transferred pattern is transferred to the substrate W. Further, the stage 110 is provided so as to be movable in the optical axis direction, and is also provided so as to be movable in the θ direction (rotation direction around the optical axis).

  Next, the process of exposing the substrate W using the exposure apparatus 1 will be described. As a precondition, the ratio of the stray light intensity to the light intensity of the image area projected on the stage 110 is approximately 10% when i-line is used, and less than 1% when a KrF excimer laser is used. It shall be. First, the mercury lamp 101 is turned on with the shutter 103 closed. The elliptical mirror 102 emits light with the direction of light emitted from the mercury lamp 101 aligned. Next, the inclination of the substrate W and the reticle 10 is corrected by a correction device using a stepping motor or the like (not shown). Next, the opening of the reticle blind 107 is controlled so as to irradiate the necessary portion of the reticle 10 with light.

  Here, the reticle blind 107 will be described. FIG. 2 is a schematic perspective view for explaining the position of the reticle blind with respect to the reticle. A reticle blind 107 composed of four rectangular blinds 17A, 17B, 17C, and 17D is provided between the fly-eye lens 106 and the reflecting mirror 108. Each of the four blinds 17A, 17B, 17C, and 17D restricts an area to be irradiated with light with respect to the upper, lower, left, and right sides of the reticle 10. The adjacent blinds 17A, 17B, 17C, and 17D are configured to be movable so as to partially overlap each other and to be able to change the aperture amount. Here, the reticle 10 and the reticle blind 107 overlap optically but are mechanically separated. In FIG. 2, the reticle 10 is indicated by a dotted line.

  Next, the stage 110 is moved so that the substrate W is positioned at the first shot position. The steps so far may be performed in any order. Next, the shutter 103 is opened, and the light emitted from the mercury lamp 101 passes through the reflecting mirror 104, the interference filter 105, the fly-eye lens 106, the reticle blind 107, the reflecting mirror 108, the condenser lens 109, the reticle 10, and the projection optical unit PL. Irradiate the substrate W. When the total amount of irradiation light reaches the appropriate exposure amount of the photoresist 11 (determined by the characteristics of the photoresist 11), the shutter 103 is closed. Next, the stage 110 is moved, and the next area is similarly exposed. This is repeated, and the exposure process is completed when all the areas to be exposed are exposed on the substrate W.

  Thereafter, the pattern drawn on the reticle 10 is reduced and transferred to the substrate W by performing processes such as PEB (Post Exposure Bake: post-exposure baking process), development, and post baking. In this way, the pattern on the reticle 10 is projected onto the substrate W in a reduced scale. Here, it is also preferable to use a KrF excimer laser (wavelength 248 nm) or the like having a shorter wavelength instead of the mercury lamp as the light source. This is because the minimum line width becomes smaller in proportion to the exposure wavelength, so that it is possible to cope with a pattern having a higher density.

  In the process of processing the substrate W in this manner, the optical system is exposed to ultraviolet light. In addition, chemical substances such as HMDS (hexamethyldisilazane) and ammonia are present in the exposure apparatus 1 in a small amount. These chemical substances are radicalized by ultraviolet light, and solids such as silicon oxide are generated by the radicals. The solid matter adheres to the surface of a lens or the like constituting the optical system, so that the optical system is contaminated and fogging occurs. Due to this fogging, ultraviolet light used for exposure is scattered, and stray light is generated. When the photoresist 11 is exposed, if stray light enters, a portion that is not originally exposed is exposed, so that it is difficult to accurately transfer the pattern of the reticle 10 to the photoresist 11. Therefore, it is preferable to regularly measure the light intensity and stray light intensity of the image area projected on the stage 110 and maintain the state in which the pattern of the reticle 10 can be accurately transferred to the photoresist 11. In this case, the reticle blind 107 is opened beyond the transfer area of the reticle 10, and the light intensity and stray light intensity of the image area projected onto the stage 110 are measured using a measurement method described later, and a prescribed ratio (for example, mercury It is preferable to use an exposure method in which an exposure step is performed after confirming that the lamp i-line is less than about 10%. For this purpose, it is preferable to detect the light intensity and stray light intensity of the image area projected on the stage 110 as numerical values. Since the specified ratio varies depending on the ABC parameter of the photoresist 11, it is preferably determined for each photoresist.

  Therefore, a configuration for measuring the light intensity and stray light intensity of the image area projected on the stage 110 as numerical values will be described. FIG. 3 is a plan view showing a state in which the light amount sensor 112 is mounted on the stage 110 instead of the substrate. In this state, the light intensity of the image 13 projected on the stage 110 and the stray light intensity are measured. The light amount sensor 112 is mounted on the stage 110 and moves in a direction crossing the light (in the present embodiment, a direction orthogonal to the light) in synchronization with the stage 110. The light intensity and stray light intensity of the image 13 are measured with the reticle 10 and the substrate W removed (see FIG. 1).

  FIG. 4 is a flowchart showing the procedure for measuring and maintaining the light intensity and stray light intensity of the image 13 in the exposure apparatus 1 in the case of having the configuration of FIG. Hereinafter, description will be given according to this flowchart. This measurement is performed with the reticle 10 and the substrate W removed.

  First, as step 1, the reticle blind 107 is expanded beyond the opening when the reticle 10 is used. By this step, stray light can be measured with respect to an area beyond the opening of the reticle 10, and the stray light intensity in a wider range can be guaranteed. In this case, it is also preferable to set the maximum opening of the reticle blind 107. By setting in this way, it is possible to guarantee the maximum value of stray light for all the reticles 10 that the exposure apparatus 1 can handle. It becomes.

  Next, as step 2, the shutter 103 is opened. In this step, light from the light source is irradiated onto the reticle blind 107 as a shield having an opening. Then, the condenser lens 109 and the projection optical unit PL focus the light beam corresponding to the opening of the reticle blind 107, and the image 13 similar to the opening of the reticle blind 107 is projected onto the stage 110. In this case, it is preferable that the imaging plane is focused by correcting the thickness of the light amount sensor 112.

  Next, as step 3, the light intensity sensor 112 is moved by moving the stage 110 in a direction intersecting the optical axis (in this embodiment, a direction orthogonal to the optical axis) to measure the light intensity distribution in the region of the image 13. . At this time, the light intensity (stray light intensity) in the region outside the image 13 shielded by the reticle blind 107 is also measured. That is, the measurement is performed by moving one light quantity sensor 112 in and out of the image 13.

  Next, as step 4, a relative luminous intensity map is created. 5A and 5B are relative light flux intensity maps showing the relative light intensity distribution. As the relative luminous intensity map, as shown in FIG. 5A, the initial value is 100% in the image 13 to which the opening surrounded by the reticle blind 107 is transferred, and 0 in the region to which the reticle blind 107 is transferred. % Relative light intensity. Here, when a substance that cloudes the optical system including the projection optical unit PL is attached, stray light is generated in the region where the reticle blind 107 is transferred due to irregular reflection caused by this substance, as shown in FIG. This stray light is detected by measurement.

  Next, as step 5, the ratio of the light intensity and the stray light intensity of the image 13 is compared with a predetermined reference value, and when the ratio becomes a value equal to or higher than the reference value, the optical system including the projection optical unit PL. Clean and replace For cleaning, for example, a waste cloth containing water (pure water is preferable) is used for cleaning, and then water and ethanol are replaced with a waste cloth containing ethanol in order to suppress the occurrence of uneven drying, followed by drying. It is preferable to use a process. Further, when the contamination state of the members constituting the optical system including the projection optical unit PL is so great that it is difficult to clean by cleaning, the contaminated members may be replaced. Here, the reference value of the ratio between the light intensity and the stray light intensity of the image 13 depends on the characteristics of the photoresist 11, but is approximately 10% when i-line is used, and when a KrF excimer laser is used. It is preferable to use about 1% as a reference.

  Next, as step 6, the light intensity and stray light intensity of the image 13 are measured in a state where the reticle blind 107 is set to a region wider than the opening of the reticle 10 or the maximum opening of the reticle blind 107. Confirm that the ratio of the stray light intensity to the intensity is less than a predetermined reference value. Thereafter, in the exposure apparatus 1, the substrate W is mounted instead of the light amount sensor, the reticle 10 is mounted between the condenser lens 109 and the projection optical unit PL, and the process of exposing the substrate W is continued, so that the stray light intensity is increased. It is possible to provide an exposure method capable of performing exposure after grasping the ratio.

  By performing the above steps, the exposure apparatus 1 can be maintained at a necessary and sufficient frequency. It is also preferable to perform Step 1 to Step 5 again after the maintenance work of the reduction optical lens is completed, and it is possible to confirm that stray light is reduced. The flow in the case of performing this step is indicated by a dotted line in FIG.

  Hereinafter, effects of the present embodiment will be described.

  Since the stray light intensity is directly measured using the light quantity sensor 112, a dedicated reticle or the like is not required. Therefore, the cost for measurement can be reduced. Further, when the light quantity measurement sensor attached to the exposure apparatus 1 is used as the light quantity sensor 112, it is possible to perform measurement without incurring costs.

  Compared with a method of using a reticle having a dedicated pattern, exposing and developing a monitor wafer, and measuring a pattern width using a pattern measuring device, the time required for the measurement can be shortened.

  In a method that uses a reticle with a dedicated pattern, exposes and develops a monitor wafer, and measures the pattern width using a pattern measuring device, the thickness of the photoresist varies, the development conditions fluctuate, the pattern It is difficult to measure the intensity of stray light purely because there are multiple factors such as errors in the measuring device, but by using the measurement method of this embodiment, these factors are removed and only the intensity of stray light is purely measured. It becomes possible to measure.

  Since the intensity of stray light is measured by scanning the single light quantity sensor 112, it is possible to measure the intensity of stray light by eliminating the influence of sensitivity unevenness between the light quantity sensors that occurs when a plurality of light quantity sensors are used. Become.

  When the opening degree of the reticle blind 107 is maximized, it is possible to measure when the stray light intensity is the highest, and it is possible to guarantee the stray light intensity for all the reticles 10 that the exposure apparatus 1 can handle.

  When the opening degree of the reticle blind 107 is aligned with the opening of the reticle 10, it is possible to measure the stray light intensity generated with respect to the reticle 10, and to provide an exposure method capable of guaranteeing the stray light intensity in a state where the quality is not excessive. It becomes possible to do.

  Although depending on the characteristics of the photoresist 11, when the ratio of the stray light intensity to the light intensity of the image 13 reaches about 10% when using the i-line, and about 1% when using the KrF excimer laser. , A defect occurs. Therefore, when the ratio of the stray light intensity to the light intensity of the image 13 reaches the above value, it is possible to suppress the occurrence of defects due to stray light by maintaining and preparing the optical system.

  As a cleaning method, use a step of cleaning with a waste cloth containing pure water, and then substituting ethanol with a waste cloth containing ethanol for drying and then drying in order to suppress the occurrence of uneven drying. Therefore, cleaning can be performed without using toxic substances, and maintenance work can be performed safely.

  By forming a relative luminous flux intensity map showing the relative light intensity distribution, the maximum amount can be extracted without averaging the stray light intensity. For this reason, it is possible to suppress (prevent) the occurrence of defects due to stray light (generated where the stray light intensity is maximum).

  W ... Substrate, 1 ... Exposure apparatus, 10 ... Reticle, 11 ... Photoresist, 12 ... Wafer, 13 ... Image, 17A ... Blind, 17B ... Blind, 17C ... Blind, 17D ... Blind, 101 ... Mercury lamp, 102 ... Ellipse Mirror, 103 ... Shutter, 104 ... Reflector, 105 ... Interference filter, 106 ... Fly eye lens, 107 ... Reticle blind, 108 ... Reflector, 109 ... Condenser lens, 110 ... Stage, 112 ... Light quantity sensor.

Claims (8)

A measurement method for measuring stray light of a projection exposure apparatus,
The projection exposure apparatus includes:
A light source;
A shield with an opening for receiving light from the light source;
A lens that focuses the luminous flux obtained through the opening;
A stage for projecting the light beam focused by the lens as an image including a shape similar to the opening;
A projection exposure apparatus comprising:
Projecting light emitted from the light source onto the stage as the image;
Measuring the intensity distribution of the luminous flux in a wider range than the area of the image;
A measurement method for measuring stray light of a projection exposure apparatus characterized by comprising: The measurement method according to claim 1,
A measurement method for measuring stray light of a projection exposure apparatus, wherein the size of the opening is changeable, and the intensity of the light beam is measured in a state where the opening is opened to a maximum size.   3. The measurement method according to claim 1, wherein the intensity of the light beam is measured by measuring the intensity distribution of the light beam by moving one light sensor in and out of the image. Measuring method to measure. An exposure method for a projection exposure apparatus,
The projection exposure apparatus includes:
A light source;
A shield with an opening for receiving light from the light source;
A lens that focuses the luminous flux obtained through the opening;
A stage for projecting the light beam focused by the lens as an image including a shape similar to the opening;
A projection exposure apparatus comprising:
Projecting the light emitted from the light source onto the stage as the image;
When the ratio of the light intensity of the area outside the image area to the light intensity of the image area is less than a predetermined value, the transfer area is below the range irradiated with the luminous flux. An exposure method for a projection exposure apparatus, wherein exposure is performed using a reticle. The exposure method according to claim 4,
The predetermined ratio is 10% when i-line of a mercury lamp is used as a light source, and 1% when a KrF excimer laser is used. A maintenance method for a projection exposure apparatus,
The projection exposure apparatus includes:
A light source;
A shield with an opening for receiving light from the light source;
A lens that focuses the luminous flux obtained through the opening;
A stage for projecting the light beam focused by the lens as an image including a shape similar to the opening;
A projection exposure apparatus comprising:
Projecting the light emitted from the light source onto the stage as the image;
A projection exposure apparatus characterized in that maintenance work is performed when a ratio of light intensity in an area outside the image area to a light intensity in the image area is equal to or greater than a predetermined value. Maintenance method. The maintenance method according to claim 6, wherein
The predetermined ratio is 10% when the i-line of a mercury lamp is used as a light source, and 1% when a KrF excimer laser is used. The maintenance method according to claim 6 or 7,
The maintenance method includes a step of cleaning with water, then cleaning with ethanol, and drying.

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