JP2002296005A - Aligning method, point diffraction interference measuring instrument, and high-accuracy projection lens manufacturing method using the same instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PDI(point diffraction interferometry)-type interference measuring instrument etc., allowing the alignment of a tested surface with the interference measuring instrument by using a simple procedure. SOLUTION: This aligning method is used in a measuring method for measuring the optical characteristics of a tested object 104 by causing measuring light to interfere with reference light and detecting a phase difference. The measuring light is one of two light beams into which light generated from point light source generating means 101, 102, and 103 is separated after it is passed through the tested object 104. The reference light is a spherical wave generated by passing the other beam through a minute transmission part 106a. This aligning method is used to align the other beam with the transmission part 106a and has a process for disposing a first reflection member 112 (215) in the proximity of a condensing point CP conjugated with the transmission part 106a and formed by the light transmitted by the tested object 104, and a process for detecting vertex reflected light from the reflection member 112 to adjust the position of the reflection member 112 in the optical axis direction based on reflected light information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interferometer and, more particularly, to Point Diffraction Interferometry (hereinafter "PDI").
That. ) Type interferometer and its alignment method,
And a method for manufacturing a high-precision projection lens using the apparatus.

[0002]

2. Description of the Related Art Semiconductor manufacturing apparatuses are used to manufacture semiconductor devices. For example, as a typical semiconductor manufacturing apparatus, there is a reduction projection type sequential exposure apparatus (hereinafter, referred to as “stepper”). The stepper has a high-precision projection lens. In order to guarantee the accuracy of the high-precision projection lens, it is necessary to measure the transmitted wavefront aberration or the reflected wavefront aberration of the entire projection lens and the individual optical elements constituting the projection lens in the actual exposure wavelength region. .

For this reason, various interferometers using a highly coherent light source that oscillates light having a wavelength equal to or substantially equal to the exposure wavelength region have been devised.

[0004]

In recent years, high integration of semiconductor devices has been advanced. In order to cope with this high integration,
The exposure wavelength of the stepper has been shortened. For example, g-line (λ = 436n) using a high-pressure mercury lamp as a light source
m) to i-line (λ = 365 nm).
Further, the wavelength is shortened from a KrF excimer laser (λ = 248 nm) to an ArF excimer laser (λ = 193 nm).

As a result, it has become very difficult to obtain a highly coherent light source having an oscillation wavelength near the exposure wavelength.

Therefore, it has been proposed to measure a high-precision projection lens or the like using a PDI-type interferometer capable of performing high-precision interference measurement even with a light source having relatively low coherence.

FIG. 4 is a diagram showing a schematic configuration of a conventional PDI interferometer. The laser 1 as a light source emits light from the light source. The condenser lens 2 condenses the light from the light source at the position of the pinhole 3. The light emitted from the pinhole 3 can be regarded as an almost ideal spherical wave. The spherical wave from the pinhole 3 enters the test object 4. Light transmitted through the test object 4 is emitted from the emission side. Then, the light emitted from the subject 4 is
The light enters the grating 5.

The grating 5 separates the incident light into a light beam for generating a reference wave and the test light and emits the separated light to the mask 6 side. The light beam for generating the reference wave enters a pinhole 6 a formed in the mask 6. The luminous flux transmitted through the pinhole 6a can be regarded as an almost ideal spherical wave, and this is the reference light.

On the other hand, the test light is incident on an opening 6b (sized to allow the test light to pass through) 6b formed in the mask 6. Then, interference fringes are formed on the light receiving surface of the light receiving element 7 by the reference light and the test light. The interference fringe signal from the light receiving element 7 is analyzed by an arithmetic processing unit (not shown). As a result, the wavefront aberration of the test object 4 is obtained.

In such a conventional PDI-type interferometer, it is necessary to perform alignment between the interferometer and the test object every time the test object 4 is replaced. here,
The test object 4 is a variety of optical members that generate different amounts of aberration. Then, it is necessary to accurately guide the light flux transmitted or reflected by the various test objects to the position of the minute pinhole 6a. For this purpose, for example, the position of the pinhole 6a must be three-dimensionally aligned. It is very difficult to perform this alignment accurately and quickly.

Further, for the above-mentioned alignment, a configuration in which an alignment optical path is provided separately from the measurement optical path may be considered. In this configuration, a light receiving element for alignment is arranged in an optical path branched from the optical path for measurement. Then, the light quantity for measurement, which is reduced by branching, is compensated by increasing the output itself of the light source.

However, the above-mentioned KrF excimer laser or ArF excimer laser is a pulse oscillation laser. Therefore, PDs using these excimer lasers as light sources
In an I-type interferometer, damage to a lens material, a coating layer, a pinhole pattern, and the like due to laser irradiation is expected. For this reason, if an optical path for alignment is separately provided and the output of the light source is increased, the damage due to laser irradiation is further increased. As a result, it is difficult to adopt a configuration in which an alignment optical path is separately provided.

The present invention has been made in view of the above problems, and has a PDI-type interferometer capable of performing alignment of a reference beam used in a measuring method for measuring optical characteristics of a test object by a simple procedure. It is an object of the present invention to provide an apparatus, an alignment method thereof, and a method of manufacturing a high-precision projection lens manufactured using the apparatus.

[0014]

Means for solving the above problems will be described with reference to the accompanying drawings showing an embodiment.
1, 102, and 103, and the
The measurement light, which is one light of the two light beams separated after passing through the light source 4, and the other light,
The reference light, which is a spherical wave generated by passing through the reference beam 6a, interferes with each other, and detects the phase difference due to the interference, thereby using the other of the other methods used in the measurement method for measuring the optical characteristics of the test object 104. The minute transmission part 106 of light
This is an alignment method for a, wherein the first reflection member 112 (215) is conjugate with the micro-transmission portion 106a and is located near a converging point CP formed by light transmitted through the test object 104. Detecting the vertex reflected light from the first reflecting member 112 (215), and adjusting the position of the first reflecting member 112 (215) in the optical axis direction based on the reflected light information. And an alignment method comprising: Here, the optical characteristics of the surface to be measured refer to transmitted wavefront aberration, reflected wavefront aberration, surface shape, and the like.

According to a second aspect of the present invention, the light generated by the point light source generating means 101, 102, 103 is:
The measurement light which is one of the two light beams obtained by separating the reflected light from the test surface of the test object 316 and the other light which is the spherical surface generated by passing through the minute transmitting portion 106a. The other light, which is used in a measurement method for measuring the optical characteristics of the test object 316, by causing the reference light, which is a wave, to interfere with each other, and detecting a phase difference due to the interference, with respect to the minute transmitting portion 106a. A light condensing position of a light condensing optical system 110 that is conjugate with the minute transmitting portion 106a and is disposed in an optical path between the point light source generating means 101, 102, 103 and the test object 316. Arranging the first reflecting member 215 on the CP;
Detecting the vertex reflected light from the first reflecting member 215 and adjusting the position of the first reflecting member 215 in the optical axis direction based on the reflected light information. I do.

In the alignment method according to the third aspect, the first reflection member 215 may be provided with a predetermined pattern 215.
a is formed, and the vertex reflected light from the predetermined pattern 215a of the first reflecting member 215 is detected, and the first reflecting member 2 is formed based on the reflected light information.
Adjusting a position in a plane orthogonal to the 15 optical axes.

Further, in the alignment method according to the fourth aspect, based on the position of the first reflecting member 112, the second reflecting member 1 that folds the light transmitted through the test object 104.
The method further comprises a step of adjusting the position of the eleventh position.

In the alignment method according to a fifth aspect, when detecting the reflected light, the reflected light is focused on a detection surface.

Further, in the alignment method according to the present invention, the reflected light information is information on interference fringes formed by the reflected light. Here, the information on the interference fringes refers to the contrast and the like of the interference fringes.

Further, in the alignment method according to the present invention, the minute transmitting portion 106a is a pinhole.

According to an eighth aspect of the present invention, there is provided a point light source generating means 101, 102, 103, an optical element 105 for separating light passing through a test object 104 into two light beams, and the optical element 105. The member 106 provided with the minute transmitting portion 106a for passing one of the separated lights, and the measuring light as the other light and the reference light as the spherical wave generated by passing through the minute transmitting portion 106a interfere with each other. And a detector 107 for detecting a phase difference due to the interference.
And a point diffraction interferometer provided with a first reflection member 112 in the vicinity of an image point CP formed by the test object 104.

Further, in the point diffraction interference measuring apparatus according to the ninth aspect, the second reflection member 111 may return the light transmitted through the test object 104 and guide the light to the test object 104 again.
It is characterized by having.

Further, the point diffraction interference measuring apparatus according to the tenth aspect is characterized in that the first reflecting member 112 and the second reflecting member 111 can be integrally adjusted in position.

According to the eleventh aspect of the present invention, the point light source generating means 101, 102, and 103, the optical element 105 for separating the light passing through the test object 316 into two light beams, and the optical element 105 The member 106 provided with the minute transmitting portion 106a for passing one of the separated lights, and the measuring light as the other light and the reference light as the spherical wave generated by passing through the minute transmitting portion 106a interfere with each other. Let
And a detector 107 for detecting a phase difference due to the interference.
A condensing optical system 110 is provided in an optical path between the light-receiving optical system 110 and the test object 316, and is conjugated with the minute transmitting portion 106 a and has a converging point CP of the condensing optical system 110.
A point diffraction interferometer provided with a first reflection member 215 in the vicinity is provided.

A point diffraction interference measuring apparatus according to a twelfth aspect is characterized in that the first reflecting member 112 (215) includes a mechanism MT which can be inserted and removed.

The point diffraction interference measuring apparatus according to claim 13 is characterized in that the first reflecting member 215 has a predetermined pattern 215a.

The point diffraction interference measuring apparatus according to claim 14 is characterized in that the first reflecting member 215 has an opening C2.

In the point diffraction interference measuring apparatus according to the present invention, the detector 107 detects the reference light in an optical path between the member 106 provided with the minute transmitting portion 106a and the detector 107. An auxiliary optical system 114 for focusing light on a surface is provided.

The point diffraction interference measuring apparatus according to claim 16 is characterized in that the auxiliary optical system 114 has a mechanism that can be inserted and removed.

The point diffraction interference measuring apparatus according to claim 17 is characterized in that the optical element 105 is a diffractive optical element.

In the point diffraction interference measuring apparatus according to the eighteenth aspect, the member 106 provided with the minute transmitting portion 106a is provided.
Is a transmitting portion 106b having a size that allows the measurement light to pass therethrough.
It is characterized by having.

According to a nineteenth aspect of the present invention, there is provided a method of manufacturing a high-precision projection lens manufactured by using the point diffraction interferometer according to any one of the eighth to eighteenth aspects. .

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0034]

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

(First Embodiment) FIG. 1 is a diagram showing a schematic configuration of an interference measuring apparatus according to a first embodiment. First, a basic configuration for measuring the test object 104 will be described, and then an alignment procedure for this measurement will be described. here,
The test object 104 is a projection lens composed of a plurality of lenses. However, the present invention is not limited to this, and is also applicable to an optical system including a single lens and a plurality of mirrors.

A laser 101 serving as a light source emits light from the light source. The condenser lens 102 condenses the light from the light source at the position of the pinhole 103. The light emitted from the pinhole 103 can be regarded as an almost ideal spherical wave. Laser 101
, The condenser lens 102 and the pinhole 103 form a point light source generating means. The spherical wave from the pinhole 103 enters the collimator lens 108. Collimator lens 1
08 converts the light from the pinhole 103 into a substantially parallel light beam. The substantially parallel light beam from the collimator lens 108 enters the half mirror 109. The half mirror 109 is
This substantially parallel light beam is reflected to the objective lens 110 side. The objective lens 110 converges the substantially parallel light beam once to the position P1, and then diverges the light toward the test object 104. This divergent light enters the object 104 from the side 104a.

The light transmitted through the test object 104 is emitted from 104b and is reflected at the vertex reflection position (cat's eye point) C
It is focused on P. The light collected at the vertex reflection position CP is
The light becomes divergent light and enters the turning spherical reflection mirror 111.

The turning spherical reflection mirror 111 is adjusted to a position where interference fringes with good contrast are formed by an alignment procedure described later.

The reflected light from the spherical reflecting mirror 111 passes through the same optical path as the outward path, and the test object 104 and the objective lens 1
10 and re-enters the half mirror 109.

The light from the test object 104 passes through the half mirror 109 this time. The light transmitted through the half mirror 109 enters the condenser lens 113. Condensing lens 113
Emits the incident light to the grating 105 side so as to condense it to the condensing position P2. The grating 105 separates incident light into reference light and test light by a diffraction effect.
The separated reference light passes through a pinhole 106a formed in the mask 106. Thereby, the reference light is
It is converted to an ideal spherical wave. The separated test light passes through an opening 106b formed in the mask 106.

Then, interference fringes due to interference between the reference light and the test light are formed on the light receiving surface of the light receiving element 107. Monitor M
N indicates this interference fringe. In addition, the arithmetic processing unit PC
Calculates the transmitted wavefront aberration (including the defocus term and the tilt term) of the test object 104 based on the phase difference signal of the interference fringe from the light receiving element 107.

(Alignment Procedure) Next, an alignment procedure performed as a pre-stage for performing the interference measurement will be described. In order for the interference fringes having a good contrast to be formed on the light receiving surface of the light receiving element 107 by the above configuration,
It is necessary that the position P2 where the test light is condensed by the condenser lens 113 and the position of the pinhole 106a exactly match.

When the test object 104 is replaced with another test object, the condensing position P2 of the condensing lens 113 is shifted by the pinhole 10 due to the position of the test object and the aberration characteristics of the test object.
Defocusing or the like occurs at the position 6a. Here, as described above, it is very difficult to accurately and quickly adjust the position of the pinhole 106a three-dimensionally.

Further, the interference measurement device performs calibration (device calibration) of the device. Then, in order to maintain the sameness of the calibration for the various test objects 104, it is desirable not to adjust the position or the like of a component (for example, the pinhole 106a) inside the interference measurement apparatus after the calibration. Therefore, the alignment procedure described below is performed.

(1) Test object 104 such as a high-precision projection lens
At a predetermined position of the interference measurement device.

(2) Plane reflection mirror 112 for vertex reflection
Is inserted into the position shown by the dotted line near the light condensing position (vertex reflection position) CP on the 104b side of the test object 104. In this state, the light condensing position P2 by the light condensing lens 113 does not match because the position of the pinhole 106a is defocused (z direction) and shifted (x, y directions).

(3) Insert the auxiliary lens 114 at the position shown by the dotted line between the mask 106 and the light receiving element 107. The auxiliary lens 114 conjugates the position of the pinhole 106a with the light receiving surface of the light receiving element 107. That is, the auxiliary lens 1
14 condenses the light from the pinhole 106a to the position P3. With this configuration, the light amount detection sensitivity on the light receiving surface can be improved.

(4) Plane reflecting mirror 112 for vertex reflection
Is moved (scanned) in small amounts along the z-axis direction, which is the optical axis. Then, the light amount fluctuation of the light receiving element 107 due to the movement of the plane reflection mirror 112 is detected.

(5) The plane reflecting mirror 112 is stopped when the light amount detected by the light receiving element 107 is maximized. In this state, the reflection surface of the plane reflection mirror 112 coincides with the vertex reflection position CP.

(6) Spherical reflective mirror 1 having a known radius of curvature
The relative positional relationship between the mirror 11 and the plane reflection mirror 112 is determined in advance. Therefore, when the position of the plane reflection mirror 112 in the optical axis z direction is determined, the position of the spherical reflection mirror 111 in the optical axis z direction is determined. The positioning in the x and y directions is performed by another method.

(7) The auxiliary lens 114 is retracted outside the optical path.

(8) Interference measurement is performed using the interference fringes formed on the light receiving surface of the light receiving element 107.

In the above alignment procedure, vertex reflection is used. In the vertex reflection, the shift of the plane reflection mirror 112 in the direction (x, y directions) perpendicular to the optical axis z direction has no effect. For this reason, the plane reflection mirror 112
Only the position in the optical axis z direction needs to be considered. Therefore, strict alignment is not required for the position of the plane reflection mirror 112 in the direction (x, y directions) perpendicular to the optical axis z direction. Then, in this state, the plane reflecting mirror 112 is scanned and moved in the optical axis z direction. Thereby, the condensing position P2 of the reference light
And the pinhole 106a can be aligned in the optical axis z direction.

Further, by displaying the change in the light amount of the reference light or the test light on the monitor MN, the alignment state in the optical axis z direction can be observed. In addition, the alignment described in the above (1) to (8) In the procedure, the pinhole 106 detected by the light receiving element 107 is
A change in the amount of light that has passed through a is detected. But,
The alignment is not limited to the one based on the change in light amount. For example, alignment can be performed by detecting information on interference fringes such as the contrast of interference fringes. Hereinafter, an alignment procedure based on the interference fringe contrast will be described. The description of the procedure that is the same as the above procedure is omitted.

By adjusting the pinhole 103 with the plane reflecting mirror 112 inserted in the optical path, alignment in the x and y directions can be performed. When the alignment in the x and y directions is performed, interference fringes are formed on the light receiving surface of the light receiving element 107 even when the auxiliary lens 114 is not inserted into the optical path. Next, the plane reflection mirror 112 is scanned and moved in the optical axis z direction. The light receiving element 107 detects a change in contrast of the interference fringe due to the scanning movement. Next, the plane reflection mirror 1 in which the contrast of the interference fringe is maximized
Find the position of twelve. Next, the position of the spherical reflection mirror 111 whose position relative to the plane reflection mirror 112 is known is determined. Then, the plane reflecting mirror 112 is retracted from the optical path. Finally, interference measurement of the test object 104 is performed.

When the interference fringes are analyzed by the arithmetic processing unit PC, the wavefront aberration including the focus component and the tilt component of the test wave can be calculated from the information of the interference fringes. For this reason, the focus position P2 of the light beam for generating the reference wave and the pinhole 1
06a can be performed with higher accuracy.

Preferably, when causing the reference light and the test light to interfere with each other on the light receiving surface of the light receiving element 107, it is desirable that the reference light and the test light interfere with each other in a state of being made into a parallel light flux. If you make interference in the state of a parallel beam,
The stop S in the high-precision projection lens as the test object 104 and the light receiving surface of the light receiving element 107 can be conjugated. As a result, the effect of diffraction at the edge portion e of the stop S can be reduced.

(Second Embodiment) FIG. 2A is a view showing a schematic configuration of an interference measuring apparatus according to a second embodiment.
In the present embodiment, the configuration of the plane reflection mirror 215 is different from that of the first embodiment. Other configurations are the same as those of the first embodiment, and the same reference numerals are used for the same portions, and duplicate descriptions are omitted.

The plane reflecting mirror 215 of this embodiment shown in FIG. 2B has a ring-shaped pattern 215a having a low reflectance of about 10 μm or a reflectance of substantially zero on its reflection surface.
have. The procedure for positioning the plane reflecting mirror 215 in the optical axis z direction is the same as that in the first embodiment, and a description of the overlapping procedure will be omitted. In the present embodiment, it is possible to further position the plane reflection mirror 215 and the vertex reflection position CP in the x and y directions using the ring-shaped pattern 215a.

First, the alignment of the plane reflecting mirror 215 in the optical axis z direction is performed in the procedure described in the first embodiment. Next, the motor MT sets the plane reflection mirror 215 to xy.
Scan and move in the plane. When the ring-shaped pattern 215a crosses the vertex reflection position CP, the amount of light reflected from the pattern decreases. Therefore, the amount of light received by the light receiving element 107 is greatly reduced. At this time, the position of the plane reflection mirror 215 is stored as a first position coordinate in a storage unit (not shown) in the arithmetic processing unit.

Further, the motor MT is driven to continue the scanning movement of the plane reflecting mirror 215 in the xy plane. Then, the second position coordinates and the third position coordinates of the plane reflecting mirror 215 when the light receiving amount of the light receiving element 107 is greatly reduced are detected. A storage unit (not shown) in the arithmetic processing device stores the second position coordinates and the third position coordinates. Then, the arithmetic processing device PC can perform alignment for matching the center position C of the ring-shaped pattern 215a with the vertex reflection position CP based on the three data of the first to third position coordinates.

As in the first embodiment, the relative positional relationship between the plane reflecting mirror 215 and the spherical reflecting mirror 111 is known. Therefore, when the position of the plane reflecting mirror 215 in the xyz coordinates is determined, the spherical reflecting mirror 1
Eleven positions can be defined. As a result, interference fringes with good contrast can be obtained.

As a modification of this embodiment, FIG.
A plane reflection mirror 215 having the configuration shown in FIG. The plane reflecting mirror 215 is a spherical reflecting mirror 1
11 can be used integrally. In this modification,
Low reflectance ring-shaped pattern 215a having a width of about 10 μm
Is similar to that of the second embodiment. The difference is that a circular opening C2 having a diameter of about several mm is provided at the center.

As in the first embodiment, alignment between the vertex reflection position CP in the optical axis z direction and the plane reflecting mirror 215 is performed. Here, the light that has entered the vicinity of the center of the plane reflecting mirror 215 passes through the circular opening C2. The transmitted light is reflected by the spherical reflecting mirror 111 moving integrally with the plane reflecting mirror 215.
And is reflected. Then, this light exits again from the central opening C2 of the plane reflection mirror 215. Here, the center position of the radius of curvature of the spherical reflection mirror 111 and the center of the center opening C2 of the plane reflection mirror 215 are integrally moved so as to coincide with each other. With such a configuration, alignment of the vertex reflection position CP and the plane reflection mirror 215 in the optical axis z direction can be performed.

Next, the plane reflection mirror 215 is aligned in the x and y directions with respect to the vertex reflection position CP. This alignment is performed by first scanning and moving the plane reflecting mirror 215 in the xy plane in the same manner as described in the second embodiment.
At least three position coordinates where the vertex reflection position CP crosses the ring pattern 215a are obtained. At this time, even when the center opening C2 crosses the vertex reflection position CP, the light receiving element 10
The light quantity at 7 decreases. However, the ring-shaped pattern 215a (about 10 μm in width) and the center opening C2 (several m in diameter)
m) is completely different in size. For this reason, the time during which the amount of light decreases is different. Therefore, the vertex reflection position C
Whether P crosses the ring-shaped pattern or the center opening C2 can be easily identified.
Therefore, alignment of the plane reflection mirror 215 in the x and y directions can be performed.

In this modification, the plane reflection mirror 215 and the spherical reflection mirror 111 are integrally formed as described above. Therefore, the interference measurement can be performed immediately after the alignment of the plane reflection mirror 215 in the x, y, and z directions is completed.

(Third Embodiment) FIG. 3A is a diagram showing a schematic configuration of an interference measuring apparatus according to a third embodiment.
The basic configuration is the same as the above-described first and second embodiments, and the same portions are denoted by the same reference numerals, and redundant description will be omitted.

In the first and second embodiments,
The test object 104 is a high-precision projection lens and measures a transmitted wavefront, whereas the present embodiment differs from the first embodiment in that the test object 104 is a single spherical mirror 316 and measures a reflected wavefront.

In the case of a reflection type test object, a flat reflection mirror 215 whose configuration is shown in FIG.
At the light condensing position (vertex reflection position) CP. And
The alignment in the x, y, and z directions is performed in the same procedure as described in the second embodiment. Then, the plane reflection mirror 21
A reflective spherical mirror 316 whose relative position with respect to 5 is determined in advance is arranged. Thereby, the spherical mirror 3
The interference of the wavefront aberration of the reflected wavefront from 16 can be easily measured.

Further, by using the interference measuring apparatus described in each of the above embodiments, the wavefront aberration of the projection lens can be easily measured. Therefore, a highly accurate projection lens can be manufactured.

[0071]

As described above, a PDI-type interferometer capable of performing alignment between a surface to be measured and an interferometer by a simple procedure, an alignment method thereof, and a high-frequency device manufactured using the apparatus. A method for manufacturing a precision projection lens system can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a PDI-type interference measuring apparatus according to a first embodiment of the present invention.

FIGS. 2A, 2B, and 2C are schematic configuration diagrams illustrating a PDI-type interference measuring apparatus according to a second embodiment of the present invention.

FIGS. 3A and 3B are schematic configuration diagrams illustrating a PDI interference measuring apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of a conventional PDI-type interferometer.

[Explanation of symbols]

 101,1 laser light source 102,2 condenser lens 103,3 pinhole 104,4 test object 105,5 grating 106,6 mask 106a, 6a pinhole 106b, 6b opening 107,7 light receiving element 108 collimator lens 109 half Mirror 110 Objective lens 111 Folded reflective spherical mirror 112, 215 Planar reflective mirror for apex reflection 113 Condensing lens 114 Auxiliary lens 215a Alignment pattern 316 Reflective test object PC Computer processing unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryosuke Inoue 3-2-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (72) Inventor Ryoji Nakamura 3-2-2-3 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Nikon Corporation 2F064 AA06 BB04 FF01 GG00 GG12 GG15 GG22 GG58 JJ01 2F065 AA02 AA03 AA04 AA20 BB05 BB22 CC22 EE00 FF52 GG04 GG12 HH13 HH15 JJ08 LL19 LL19 LL04 LL04 LL04

Claims (19)

[Claims] 1. A measuring light, which is one of two light beams separated from a point light source generated by a point light source generating unit after passing through a test object, and a measuring light, which is another light, The other light used in the measurement method for measuring the optical characteristics of the test object by causing the reference light, which is a spherical wave generated by passing through the transmitting portion, to interfere with each other, and detecting a phase difference due to the interference. A method of aligning the light with respect to the minute transmitting portion, wherein the first reflecting member is conjugated to the minute transmitting portion and arranged near a focal point formed by light transmitted through the test object; Detecting the vertex reflected light from the first reflecting member and adjusting the position of the first reflecting member in the optical axis direction based on the reflected light information. 2. A measuring light, which is one of two light beams, which are light beams generated by a point light source generating means, wherein the reflected light from the surface of the test object is separated, and the other light beam. In the measurement method for causing the reference light, which is a spherical wave generated by passing through the minute transmission portion, to interfere with each other, and detecting a phase difference due to the interference, the optical characteristic of the test object is measured. A method of aligning the other light to be used with respect to the minute transmitting portion, wherein the focusing optics are conjugate with the minute transmitting portion and arranged in an optical path between the point light source generating unit and the test object. Arranging a first reflecting member at a light condensing position of the system; detecting vertex reflected light from the first reflecting member; and an optical axis direction of the first reflecting member based on the reflected light information. Adjusting the position of the Door way. 3. A predetermined pattern is formed on the first reflection member, and a vertex reflection light from the predetermined pattern of the first reflection member is detected, and the first reflection member detects the vertex reflection light based on the reflection light information. 3. The alignment method according to claim 1, further comprising: adjusting a position in a plane orthogonal to the optical axis of the one reflecting member. 4. The method according to claim 1, further comprising the step of adjusting the position of a second reflecting member that folds light transmitted through the test object based on the position of the first reflecting member. Alignment method. 5. The alignment method according to claim 1, wherein when detecting the reflected light, the reflected light is focused on a detection surface. 6. The alignment method according to claim 1, wherein the reflected light information is information on interference fringes formed by the reflected light. 7. The alignment method according to claim 1, wherein the minute transmitting portion is a pinhole. 8. A member comprising: a point light source generating means; an optical element for separating light passing through the test object into two light beams; and a member having a small transmitting portion for passing one of the lights separated by the optical element. The other light, the measurement light, and the reference light, which is a spherical wave generated by passing through the minute transmitting portion, interfere with each other,
A detector for detecting a phase difference due to the interference, comprising: a first reflection member near the image point formed by the test object while being conjugate to the minute transmission portion. A point diffraction interference measurement apparatus, characterized in that: 9. The point diffraction interference measuring apparatus according to claim 8, further comprising a second reflection member that folds light transmitted through the test object and guides the light back to the test object. 10. The point diffraction interference measuring apparatus according to claim 8, wherein the first reflection member and the second reflection member can be integrally adjusted in position. 11. A member comprising: a point light source generating means; an optical element for separating light passing through a test object into two light fluxes; and a member having a minute transmitting portion for passing one of the lights separated by the optical element. The other light, the measurement light, and the reference light, which is a spherical wave generated by passing through the minute transmitting portion, interfere with each other,
A detector for detecting a phase difference due to the interference, comprising: a light condensing optical system in an optical path between the point light source generating means and the test object; A point diffraction interference measurement device, which is conjugated with the first and second light sources and is provided with a first reflecting member near a light converging point of the light converging optical system. 12. The apparatus according to claim 7, wherein said first reflection member has a mechanism which can be inserted and removed.
The point diffraction interference measurement apparatus according to any one of the above. 13. The apparatus according to claim 8, wherein said first reflection member has a predetermined pattern.
The point diffraction interference measurement apparatus according to any one of the above. 14. The point diffraction interference measurement apparatus according to claim 8, wherein the first reflection member has an opening. 15. An auxiliary optical system for converging the reference light on a detection surface of the detector, in an optical path between the member having the minute transmitting portion and the detector. Claim 8 to Claim 1
5. The point diffraction interference measurement apparatus according to any one of 4. 16. The point diffraction interference measurement apparatus according to claim 15, wherein said auxiliary optical system has a mechanism capable of being inserted and removed. 17. The point diffraction interference measurement apparatus according to claim 8, wherein the optical element is a diffractive optical element. 18. A member according to claim 8, wherein said member provided with said minute transmitting portion includes a transmitting portion having a size through which said measuring light can pass. Point diffraction interferometer. 19. A method for manufacturing a high-precision projection lens manufactured by using the point diffraction interference measuring apparatus according to claim 8. Description: