JPH0365623A - Method and apparatus for measuring distribution of illuminance on entrance pupil - Google Patents

Abstract

PURPOSE:To enable maximum display of a resolution performance of an exposure device or an inspecting optical system by determining the distribution of illuminance on an entrance pupil plane of a lens automatically and by measuring and correcting partial coherency of an illuminating system and the degree of telecentricity thereof. CONSTITUTION:While a maximum light flux 10 passing through the whole of an entrance pupil 9 of a reducing lens 2 is as shown by broken lines, an illuminating light flux 11 coming out of an illuminating system 7 actually is as shown by oblique lines. This illuminating light flux 11 is passed through a pinhole 3 of a detecting unit 8 of distribution of illuminance on the pupil and observed at a position being apart by a prescribed distance (h) therefrom. Thereby the distribution of illuminance corresponding to the distribution of illuminance on the entrance pupil 9 of the reducing lens 2 can be measured. By disposing a two-dimensional sensor 4 and taking in the distribution of illuminance thereby, accordingly, an image 43 of a light source on the entrance pupil 9 having an outer periphery 42 is obtained. Partial coherency is determined by a prescribed formula from the size thereof corresponding to the entrance pupil of the reducing lens 2 and the size of the image 43 of the light source determined by measurement and then the barycenter thereof is determined. Thereby the amount of central deviation of the light source image is determined and these are corrected. Thereby a resolution performance can be displayed at the maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical device used for exposure transfer and inspection of fine patterns of semiconductors and the like.

(Prior art) With the progress of conductor technology, especially its higher integration, there are increasing demands on optical systems such as exposure equipment that transfers fine patterns onto wafers and inspection equipment that uses microscopes that inspect transferred patterns. Performance specifications are becoming increasingly strict.

Regarding the performance of an optical system, the resolution performance of fine patterns is particularly important. In order to improve this resolution performance, it is necessary to shorten the wavelength of the light used and increase the numerical aperture (NA).
There are ways to improve the resolution of a lens, including increasing the perture or improving optical aberrations, but there are limits to the improvement of resolution performance by these means.

Under these circumstances, the importance of copy range control of the illumination system has been highlighted as a factor in maximizing resolution performance.

Optical Technology Handbook (Breakfast Shoten 1968) P11
6 to P218, Koehler illumination is used in the illumination systems of projection exposure apparatuses, microscopes, etc. in order to make the illuminance distribution uniform on a sample such as a wafer. In this illumination, an image of an illumination light source, such as a lamp, is formed on the entrance pupil of a projection optical system or a U-microscope objective. At this time,
The ratio of the size (diameter) of the light source image on the entrance pupil to the size (diameter) of the entrance pupil is called a partial copy range or σ value. When the size of the light source image matches the entrance pupil diameter, the σ value is 1
On the other hand, when a spot is formed on the entrance pupil using a laser light source or the like, the σ value becomes 0, and this is called coherent illumination.

Generally, lenses used in optical systems have optical aberrations, so the relationship between σ value and resolution is as shown in Figure 22.
Choosing an appropriate σ value is important in maximizing the resolution performance of the lens.

Furthermore, if the center 44 of the pupil 9 on the entrance pupil and the center 45 of the light source image 43 are shifted as shown in Fig. 23, the luminous flux of the illumination light irradiated to one point on the sample becomes as shown in Fig. 24. Since the axis 47 of the light beam is tilted from the lens optical axis 48, the illumination is non-telecentric (the optical axis is not perpendicular to the sample surface), and as a result, the pattern transferred by exposure or the image observed with a microscope is asymmetrical. The shape is undesirable.

In this way, it is important to control the copy range of the illumination system in order to maximize the optical performance of projection exposure equipment and inspection optical systems. It is necessary to take measurements, check whether the lighting system is in a normal state, and correct any abnormalities.

Conventionally, measurement of the illuminance distribution on the entrance pupil of such a lens has been carried out as shown in FIG. 21, taking an exposure apparatus as an example. That is, the pattern of the reticle 13 is
In an exposure apparatus that transfers chips one by one onto a wafer 6 on a wafer stage 5 in a step-and-repeat manner via a reduction lens 2 using light from A mirror 31 is inserted between the reduction lenses 2, and the conjugate position of the reduction lens 2 with the entrance pupil 9, that is, the distance from the reticle 13, is the reticle 1.
A two-dimensional optical sensor 4 was installed at a position equal to the distance between the lens 3 and the entrance pupil 9 of the lens 2, and the image of the illuminance distribution on the entrance pupil as shown in FIG. 23 was directly observed.

[Problem to be solved by the invention]

In the prior art described above, as shown in FIG. 21, a mirror 31 is inserted into the optical path, and a two-dimensional optical sensor 4 is placed at a position considered to be conjugate with the entrance pupil 9 of the lens 2 to perform measurement. In such a method, the mirror 31, the detection sensor 4, or
There is a problem in that the position of the conjugate corresponding to the center of the entrance pupil of the reduction lens 2 cannot be accurately determined due to the influence of the mounting condition of the reduction lens 2. Also, when checking the degree of telecentricity, which shows whether the center of the illumination beam is perpendicular to the sample, the reticle 13 is used to correct image distortion of the lens.
When the reduction lens 2 was tilted, accurate measurements could not be made. Furthermore, it is necessary to insert the mirror 31 and the detection sensor 4 between the reticle 13 and the reduction lens 2, which takes time and reduces productivity, and foreign matter may adhere to the reticle 13 or the reduction lens 2 during the work. The probability of Furthermore, when attempting to automate these operations, there is a problem in that the size of the apparatus inevitably increases.

In order to solve the above problems, it is an object of the present invention to accurately and automatically obtain the illuminance distribution on the lens entrance pupil of an optical system to obtain the partial copy range (σ value) of the illumination system and the telecentric degree (light source By measuring the amount of center deviation) and correcting these by moving the position of the light source based on the results, it is possible to maximize the resolution performance of projection exposure equipment and inspection optical systems. An object of the present invention is to provide a method and apparatus for measuring the distribution of illuminance in a lighting system.

[Means to solve the problem]

The above purpose is to place a small pinhole on the sample surface or at a position optically conjugate to this, place a detection sensor at a certain distance from the sample surface on the stage on which the sample is mounted, and pass through the lens and pinhole. This is achieved by measuring the illuminance distribution of the luminous flux of the illumination light.

[Effect]

That is, as shown in FIG. 2, a pinhole 3 is placed on the surface on which the wafer 6 is to be placed, and a detection sensor 4 is provided below the pinhole 3 to measure the illuminance distribution of the illumination light flux.

From the illuminance distribution data, if we observe the size do of the illumination light flux with respect to the pupil size Do and the deviation C0 of the center of the illumination light flux with respect to the center of the pupil size Do, we can determine the luminous flux of the illumination light and the maximum luminous flux of the lens. relationship is required. Furthermore, the relationship between the pupil diameter Di, the electrician's illumination luminous flux di, the center deviation Ci of the electrician's illuminating luminous flux, and the above-mentioned measured values Do, do, Co is geometrically expressed as Cf, (≧-... (2
) D i D.

It can be expressed as follows, which makes it possible to obtain the σ value and degree of telecentricity. Therefore, measurement can be performed through a lens, which was previously impossible, and measurement accuracy can be improved.Furthermore, by placing a pinhole or a sensor on the sample stage, it is possible to easily automate the measurement.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 2: FIG. 1 shows an overall configuration diagram when the present invention is applied to an exposure apparatus.

During exposure, the illumination system 7 irradiates the reticle 1 with light.
The pattern is transferred via a reduction lens 2 to a wafer 6 on a wafer stage 5 that moves in XYZ. On this wafer stage 5, an electrician illuminance distribution detection unit 8 composed of a pinhole 3 and a two-dimensional sensor 4 is arranged. The pinhole 3 of the electrician illuminance distribution detection unit 8 is placed at a position that is conjugate with the reticle 1 (that is, the position where the wafer 6 should be placed in place of the wafer 6), and the two-dimensional optical sensor 4
It is arranged so that the light receiving surface is located a certain distance below the pinhole 3.

FIG. 2 shows a measurement method using this configuration. First, the maximum luminous flux 10 passing through the entire entrance pupil 9 of the reduction lens 2 is shown by a broken line in FIG. 2, but the illumination luminous flux 11 actually coming out of the illumination system 7 is shown with diagonal lines. By passing this illumination light flux 11 through the pinhole 3 of the electrician illuminance distribution detection unit 8 and observing it at a position a certain distance away, it is possible to measure the illuminance distribution corresponding to the illuminance distribution on the entrance pupil 9 of the reduction lens 2. can. Therefore, by arranging a two-dimensional optical sensor and capturing this illuminance distribution, an image 43 of the light source on the entrance pupil 9 having the outer periphery 42 shown in FIG. 3 can be obtained. From this, the size D corresponding to the entrance pupil of the reduction lens 2
o (=D o-=D oy) and the size d of the light source image 43 determined by measurement, the partial copy range (σ value) is determined using the above equation (1), and by determining its center of gravity. , the amount of center deviation C0□C6, (telecentricity) of the light source image can be determined.

Furthermore, if the present invention is applied to an exposure apparatus using an excimer laser as a light source as seen in Japanese Patent Laid-Open No. 62-232924 and an illuminance distribution detection unit 8 (Figs. 1 and 2) is installed, the result as shown in Fig. 4 ( A) In this figure, 101 is an excimer laser, 102 is a light amount control device, 103 is an illumination optical system, 107 is an exposure control circuit, 130 is a beam deflection system,
131 is a beam-shaping device, 132° 133, 134.
142 is a lens, and 135 is an aperture stop.

In this case, exposure light is generated in a pulse form from the laser 101, and a spot light 19 focused on the entrance pupil 9 of the reduction lens 2 with each pulse is shown in FIG. The effective copy range is changed by scanning two-dimensionally within the diameter of the entrance pupil of the reduction lens and performing one exposure with a plurality of pulsed lights. In such an exposure apparatus, there are two
With the dimensional optical sensor 4, the total energy of one exposure process consisting of multiple pulses can be calculated by the accumulation effect of the sensor, or by collecting data for each pulse and adding this arithmetic, as shown in Fig. 3. It becomes possible to obtain data such as partial copy range (σ value) and the like from this data.

Although the present embodiment (FIG. 4) uses a projection type exposure apparatus as an example, this method can also be applied to a contact type or proximity type exposure apparatus.

Embodiment 2: FIG. 5 shows an embodiment in which the present invention is applied to an exposure apparatus using a single sensor such as a photomultiplier for illuminance detection.

Here, the reticle 13 is shown in FIGS. 19(a) and 19(b).
), the chromium film 28 formed on the glass plate 29
A pattern in which a plurality of pinholes 12 or one pattern of pinholes 12 are formed is used. The eruption illuminance distribution detection unit 16 detects light from the light-receiving side pinhole 15 and the single optical sensor 14 provided at a position h below the wafer 6 surface.

This detection unit is provided on the wafer stage 5, and can be moved within the XY plane by moving the stage.

Measurement of the illuminance distribution for electricians is performed as shown in FIG. The image of the pinhole 12 on the reticle 13 passes through the reduction lens 2 and is formed at a position 20 that is conjugate with the reticle 13, that is, at the same height as the surface of the wafer 6.

The light-receiving side pinhole 15 of the eruption illuminance distribution detection unit 16 provided on the wafer stage 5 is provided at a position h apart from this conjugate plane 20, and the light-receiving side pinhole 15 and the single sensor 14 are integrated. , wafer stage 5 is
Alternatively, by moving in the Y direction and measuring the amount of light while scanning, the illuminance distribution of the electrician can be measured as shown in Figure 8 (a) or 9.
Detection as shown in Figure (a) becomes possible.

Now, in this embodiment, a ground glass or a scattering plate 17 can be inserted onto the reticle 13 shown in FIG. As shown in FIG. 7, a ground glass 17 is placed on the reticle 13.
When the lens is inserted, the light from the illumination system 7 is scattered and spread widely by the ground glass 17, so that the light passing through the pinhole 12 on the reticle 13 becomes a luminous flux 46 larger than the diameter Di of the entrance pupil 9 of the reduction lens 2. The light passes through the entire aperture area of the entrance pupil 9 and enters the reduction lens 2. In this way, the light that has passed through the entire pupil is
(see Fig. 7), but if the eruption illuminance distribution detection unit 16 is scanned at a position a certain distance away from the conjugate plane 20, an illuminance distribution as shown in Figs. The diameter on the sensor surface corresponding to the diameter Di of the pupil 9 is determined.

From the illuminance distribution shown in FIGS. 8(a) and (b), (
It becomes possible to obtain the partial copy range (σ value) of the illumination system using the above-mentioned equation (1) as shown in C).

Furthermore, if we find the center 45 of the light source image (see Figure 3) from the center of gravity of the waveform obtained in Figure (a), we can calculate the deviation C0 (or Ci) of the entrance pupil from the center 44, which corresponds to the degree of telecentricity. It can be obtained by equation (2).

Incidentally, FIG. 9(a) shows the illuminance distribution obtained by performing the above measurement in the x and Y force directions, and from this it is also possible to obtain contour lines as shown in FIG. 9(b).

A plurality of pinholes 12 are formed on the reticle 13 shown in the embodiment of FIG. It is possible to measure the partial copy range and telecentricity of the light source corresponding to each point. Thereby, it is also possible to check whether the light source image is truly formed on the entrance pupil, resulting in Koehler illumination.

Embodiment ■: By using the reticle 21 having the structure shown in FIGS. 10(a), (b), and (C), the above-mentioned image can be obtained without using the ground glass 17 that can be inserted onto the reticle 13 shown in FIG. It is possible to perform the same measurements as in Example ①. That is,
On the reticle 21 shown in FIG. 1O(a), there is a
As shown in b) and (c), a plurality of pinhole pairs 22 or a single pinhole pair 22 consisting of a pinhole 12 and a pinhole 12' to which a scattering plate or ground glass 23 is attached are provided. The illuminance distribution of the electrician is measured in the same manner as in Example (2). That is, as shown in FIG.
The light passing through the pinhole 12 on the reticle 1 is focused by the reduction lens 2 at a position 20 that is conjugate with the reticle 21 . The light-receiving pinhole 15 of the illuminance distribution detection unit 16 provided on the wafer stage is moved in the X or Y direction by the wafer stage 5 to a position a certain distance away from the conjugate plane 20. In this way, it becomes possible to detect an illuminance distribution corresponding to the illuminance distribution of electricians as shown in FIG. 12(a).

Next, the reticle 2 is
1 with a pinhole 12' (
The light that passes through the lens (see FIG. 11) spreads out to be larger than the diameter of the entrance pupil 9 of the reduction lens 2. The light beam 10 that has passed through the entire entrance pupil forms an image on the reticle conjugate plane 20, so that
At a position a certain distance away from the conjugate plane 20, an illuminance distribution as shown in FIG. 12 is obtained.

Here, the two pinholes 12 and 12' of the reticle 21 are
If the distance between glj and glj is known, the distance glj on the wafer can be found by multiplying by the reduction rate m! (=mL) is determined, and from this, as shown in FIG. 12(C), the pupil diameter and center position for the illuminance distribution (in FIG. 12) are determined, and the same as in the example of FIG. , the partial copy range of the lighting system (
σ value) and the shift of the center of the light source image. Also, a plurality of pinhole pairs 22 on the reticle 21
(see Box 10)), the illuminance distribution and its bias on the entrance pupil corresponding to each point on the reticle can be determined as shown in Figure 13, and it is possible to check whether the illumination system is true Koehler illumination. You can check whether it is true or not.

Example ■: In the above Example ■, by using the reticle 21 having the structure shown in FIG. 10, the reticle 1 shown in FIG.
Although the same measurement as in Example 2 was made possible by using the ground glass 17 that can be inserted onto the surface of the reticle 24, the same measurement can be made using a reticle 24 with a lens 26 attached as shown in FIG. 14. . 25a, 25b-2 shown in the same figure (a)
5z indicates a pair of pinholes with and without lenses attached, a partially enlarged view of which is shown in (in the same figure), and a cross-sectional view in (C) of the same figure.

Embodiment V: Another embodiment will be described below with reference to FIGS. 15 and 16.

First, in FIG. 15, the illuminance distribution detection unit 16 is provided on the wafer stage 5, and the wafer stage 5 is movable in the xYz directions. This illuminance distribution detection unit 16 is separated from the light receiving pinhole 15 and the illuminance detection sensor 14 as in each of the embodiments described above.

The light passing through the pinhole 12 on the reticle 13 is focused by the reduction lens 2 into an image of 1!20 conjugate with the reticle 13. Here, the wafer stage 5 is moved in two directions and aligned in the height direction so that the pinhole 15 of the illuminance distribution detection unit 16 is located on the reticle conjugate position 20.

In this state, move the wafer stage in the XY direction and
An illuminance distribution of a pinhole image as shown in Figure (a) is obtained.

The center position 47 of the pinhole is determined from this distribution. Next, the wafer stage 5 is lowered by a certain distance in the Z direction. In this state, the wafer stage 5 is moved in the XY direction to obtain an illuminance distribution as shown in FIG. 16(C).

The center position 47 of the pinhole found in FIG. 16(a),
From the descending distance of the wafer stage, the design NA of the reduction lens (Nu+aercal aperture
), it is possible to determine the diameter Do corresponding to the pupil diameter at a position a distance away from the reticle conjugate position 20.

Therefore, by superimposing this diameter Do and the center position 47 on the measured illuminance distribution, it is possible to determine the partial copy range (σ value) of the illumination system and the amount of shift of the center of the light source. In this method, if the stroke of the wafer stage 5 in the Z direction is sufficient, the illuminance distribution measuring unit 16 on the pupil plane can be used as the illuminance distribution measuring unit on the wafer surface.

Example ■: In the above-mentioned Examples ■ to ■, the reticle conjugate position? IE
In the case where the light-receiving pinhole 15 is provided at a position distant from the light-receiving pinhole 20, a method as shown in FIG. 17 is also possible. That is, a large light-receiving window 27 and a light-receiving pinhole 12 are provided in the chromium film 28 provided on both sides of the glass 50, and the large light-receiving window 2
When the surface on which the reticle 7 is provided is aligned with the reticle conjugate position 20, the lower light receiving pinhole 12 will be placed away from the reticle conjugate position 20.

The reason why the light receiving window 27, which is wider than the pinhole, is provided on the upper surface of the glass 50 is to reduce the influence of stray light and the like.

By doing so, it is possible to coexist with an offset error measurement system such as an alignment system as seen in Japanese Patent Laid-Open No. 58-7136.

Embodiment 2: FIG. 18 also shows a specific example of the illumination system 7 of the exposure apparatus described above, and the parts other than the illumination system 7 are drawn corresponding to FIG. 5.

Light emitted from the mercury lamp 39 passes through a spheroidal mirror 40, a cold mirror 60, and a lens 61, and then enters an integrator 41. An aperture stop 30 for controlling the σ value is provided on the output surface of the integrator 41. The image of the aperture stop illuminates the reticle 13 by a mirror 62 and a condenser lens 63, and is focused on the entrance pupil 9 of the reduction lens 2.

First, the σ value is measured by the sensor 14, and the illumination system control circuit 70 changes the aperture diameter of the aperture diaphragm 30 that optimizes the σ value by changing the fixed diameter diaphragm or by changing the variable diameter diaphragm.

Next, when the center of the light source image is shifted or the illuminance distribution is tilted, move the aperture stop 30 in a direction perpendicular to the optical axis.
Or, correct it by adjusting the position of the mercury lamp 39. Also, if true Koehler illumination is not achieved, the aperture diaphragm 30
If the image of the aperture stop 30 is not formed on the entrance pupil 9 of the reduction lens 2, move the condenser lens 63 in the optical axis direction so that the image of the aperture stop 30 is accurately focused on the entrance pupil 9 of the reduction lens 2. Adjust to. These adjustments may be made manually or automatically by controlling a motor or the like.

As mentioned in the prior art section, lenses used in optical systems generally have optical aberrations, so the relationship between the σ value and resolution is as shown in Figure 22, but this curve depends on the pattern size and Varies depending on shape.

Therefore, in the exposure apparatus, in order to change the σ value of the lens to an optimal value and draw according to the drawing information (pattern dimensions, etc.) of the reticle, the partial copy range of the illumination system ( σ value), and based on that value, the 18th
The diameter of the aperture stop 30 of the illumination system shown in the figure is controlled to change the σ value. By repeating this measurement and changing the aperture diaphragm 30, it becomes possible to select an accurate σ value, and the resolving performance of the lens can be maximized.

Embodiment ■: Even in microscopes, inspection equipment, etc. that have illumination systems for observing or inspecting fine patterns of semiconductors, etc., as shown in FIG. By installing the sensor 14 on the sample stage, the partial copy range (σ value) of the illumination system and the degree of telecentricity or center shift of the light source image are checked using the method shown in Example V above. Based on this measurement result, the lighting system lamp 32. Lens 33. Or
By adjusting the position of the light guiding fiber placed at the position of the lamp 32 in the X, Y, and Z directions to eliminate misalignment of the illumination optical axis with respect to the optical axis of the lens, true Koehler illumination is achieved for the sample, ensuring good quality at all times. It makes it possible to obtain observation images.

〔Effect of the invention〕

As explained above, if the method of the present invention is implemented using the apparatus of the present invention, the partial copy range (σ
value> and the degree of telecentricity or amount of center deviation of the light source image, and based on the results, it is possible to correct the illumination system. Therefore, exposure equipment has the effect of maximizing the resolution performance of the reduction lens that forms circuit patterns on wafers, and microscopes, inspection equipment, etc. Provides Koehler illumination, allowing good observation images to be obtained at all times.

[Brief explanation of drawings]

1 to 3 show Example 2 of the present invention, in which FIG. 1 is a schematic perspective view, FIG. 2 is a sectional view with an optical path added, and FIG.
The figure is an explanatory diagram of the action. FIG. 4 is an explanatory diagram of an application example of Example I, and the same figure (A)
is a schematic perspective view, and the same figure (B) is an action explanatory view. 5 to 9 show Example 2 of the present invention, FIG. 5 is a schematic perspective view, FIGS. 6 and 7 are sectional views with optical paths added, and FIG. 8 (11), b), (C1 and FIGS. 9(a) and (b) are action explanatory diagrams. FIGS. 10 to 13 show Example 2 of the present invention;
Figures 0 (a), (b), and (C) are explanatory diagrams of the reticle;
Fig. 11 is a cross-sectional view with the optical path added, Fig. 12(a),
(b), (C) and FIG. 13 are action explanatory diagrams. FIGS. 14(a), 14(b), and 14(C) are explanatory diagrams of a reticle in Example 2 of the present invention. 15 and 16 show Embodiment V of the present invention, and the first
Figure 5 is a cross-sectional view with the optical path added, and Figures 16 (a) and (b).
). (C) is an explanatory diagram of the action. FIG. 17 is an explanatory diagram of a light-receiving pinhole in Example 2 of the present invention. FIG. 18 shows Example 2 of the present invention, and is a cross-sectional view with optical paths added. On the 19th country side, (bl is an explanatory diagram of the reticle used in Example 2. FIG. 20 is a cross-sectional view of Embodiment 2 of the present invention with the optical path added. FIG. 21 is a sectional view of the conventional example. FIG. 22 is a diagram showing the relationship between the σ value and the resolution of a general optical system, and FIGS. 23 and 24 are explanatory diagrams of problems in the prior art. 1. ... Reticle, 2... Reduction lens, 3... Pinhole, 4... Two-dimensional optical sensor, 5... Wafer stage, 6... Wafer, 7... Illumination system, 8... - Illuminance distribution detection unit, 9...Lens entrance pupil, 10...
・Maximum luminous flux of lens, 11...Illumination luminous flux, 12...
Pinhole, 13... Reticle, 14... Optical sensor for detecting illuminance distribution, 15... Light receiving pinhole, 16.
... illuminance distribution detection unit, 21 ... reticle, 30
...Aperture diaphragm. Figure 2

Claims (1)

[Claims] 1. In a method of projecting and transferring a pattern illuminated by an illumination system using a lens, a pinhole is located on a surface that is optically conjugate with the surface of the pattern with respect to the lens, Measuring the illuminance distribution of the light beam passing through the pinhole at a location a certain distance away from the hole, and calculating at least one of the partial copy range of the optical system including the lens and the telecentricity of the light beam. A method for measuring illuminance distribution on the pupil, characterized by: 2. In a device that projects and transfers a pattern illuminated by an illumination system using a lens, a pinhole provided on a surface that is optically conjugate with the surface of the pattern with respect to the lens, and a certain distance from the pinhole. An apparatus for measuring illuminance distribution on a pupil, comprising: a photodetector for detecting an illuminance distribution provided at a position separated by 1. 3. In a method of projecting and observing an image of a sample illuminated by an illumination system using a lens, a pinhole is placed on the surface of the sample on which the surface to be inspected is placed, temporarily replacing the sample. In addition, the illuminance distribution of the light beam passing through the pinhole is measured by a detector provided at a certain distance from the pinhole, and the illumination system is adjusted based on the measurement result. Method for measuring illuminance distribution on the pupil. 4. In an apparatus for observing a sample illuminated by an illumination system by projecting it through a lens, a plate member having pinholes is advanced and retracted alternately with the sample onto the surface on which the surface to be inspected of the sample is positioned. An illuminance distribution measuring device comprising: a driving means; and a detector for detecting an illuminance distribution provided at a certain distance from the pinhole. 5. Adjustment of the illumination system based on the above measurement results involves calculating at least one of the copy range and the telecentricity of the luminous flux partially based on the measurement results of the illuminance distribution, and adjusting the illumination system based on the calculation results. The position of the lamps that make up the
Adjusting at least one of the position of the lens and the state of the aperture diaphragm,
The method for measuring illuminance distribution on a pupil according to claim 3. 6. The detector that detects the illuminance distribution includes a calculation unit that calculates a partial copy range based on the detection result, a calculation unit that changes the aperture diaphragm of the illumination system based on the partial copy range, and a drive. 5. The illuminance distribution measuring device according to claim 2, further comprising a mechanism.